@article{WrightWachs2021, author = {Wright, Michelle F. and Wachs, Sebastian}, title = {The buffering effect of parent social support in the longitudinal associations between cyber polyvictimization and academic outcomes}, series = {Social psychology of education : an international journal}, volume = {24}, journal = {Social psychology of education : an international journal}, number = {5}, publisher = {Springer Science + Business Media B.V}, address = {Dordrecht}, issn = {1381-2890}, doi = {10.1007/s11218-021-09647-6}, pages = {1145 -- 1161}, year = {2021}, abstract = {Objective: Little attention has been given to the relationship between cyber polyvictimization and academic outcomes (e.g., classroom misconduct, school readiness, academic performance, absenteeism, school behavioral problems), and the factors, such as parent social support, that buffer against the negative outcomes associated with experiencing multiple forms of victimization. Addressing gaps in the literature by including a longitudinal design and objective assessments of academic outcomes, the present study examined the moderating effect of parent social support in the association between cyber polyvictimization and academic outcomes over one and a half years later. Method: Participants were 371 8th graders (50\% female) from middle schools in the United States, who completed questionnaires on offline and cyber polyvictimization and parent social support during the 7th grade. Teachers completed questionnaires on students' classroom misconduct and school readiness during 7th and 8th grade. School records were used to determine absenteeism, academic performance, and school behavioral problems (i.e., referrals, in-school suspension, out-of-school suspension) during 7th and 8th grade. Results: Findings revealed that 7th grade cyber polyvictimization was related positively to 8th grade classroom misconduct, absenteeism, and school behavioral problems, while it was negatively associated with 8th grade academic performance and school readiness. Parent social support moderated the associations between cyber polyvictimization and school readiness, academic performance, and absenteeism. Conclusion: The results highlight the importance of intervening in adolescents' experience of cyber polyvictimization to reduce negative academic outcomes.}, language = {en} } @article{WachsBilzNiproschkeetal.2018, author = {Wachs, Sebastian and Bilz, Ludwig and Niproschke, Saskia and Schubarth, Wilfried}, title = {Bullying Intervention in Schools}, series = {Journal of early adolescence}, volume = {39}, journal = {Journal of early adolescence}, number = {5}, publisher = {Sage Publ.}, address = {Thousand Oaks}, issn = {0272-4316}, doi = {10.1177/0272431618780423}, pages = {642 -- 668}, year = {2018}, abstract = {To date, little has been known about teachers' success in bullying interventions. Thus, the present study analyzes how successfully teachers intervene in real bullying situations, based on an analysis of 1,996 reports by German students aged between 12 and 15 (49.2\% female) from 24 schools. Predictors of success included intervention strategy (authoritarian-punitive, supportive-individual, supportive-cooperative intervention), bullying form (physical, verbal, relational, cyber), and the student's bullying role (bully, victim, bystander) in the particular situation. Multilevel analyses showed that supportive-cooperative intervention strategies were the most successful in dealing with bullying in both the short and long term. In the long term, students evaluated teachers as being more successful in dealing with cyberbullying compared with physical bullying. Compared with students who observed bullying, students who perpetrated it were less likely to report that teachers' interventions were successful in the short term. Implications for bullying intervention, preservice teacher-training, and future research are discussed.}, language = {en} } @article{WachsWrightVazsonyi2019, author = {Wachs, Sebastian and Wright, Michelle F. and Vazsonyi, Alexander Thomas}, title = {Understanding the overlap between cyberbullying and cyberhate perpetration}, series = {Criminal Behavior And Mental Health}, volume = {29}, journal = {Criminal Behavior And Mental Health}, number = {3}, publisher = {Wiley}, address = {Hoboken}, issn = {0957-9664}, doi = {10.1002/cbm.2116}, pages = {179 -- 188}, year = {2019}, abstract = {Background Problem behaviour theory postulates that different forms of norm violations cluster and can be explained by similar antecedents. One such cluster may include cyberbullying and cyberhate perpetration. A potential explanatory mechanism includes toxic online disinhibition, characterised by anonymity, an inability to empathise and to recognise and interpret social cues. The current study to develop a better understanding of the relationship between cyberhate and cyberbullying to inform effective intervention and prevention efforts. Aims To test the link between cyberbullying and cyberhate and whether this relationship was moderated by toxic online disinhibition. Methods Self-report questionnaires on cyberbullying, cyberhate, and toxic online disinhibition were completed by 1,480 adolescents between 12 and 17 years old (M = 14.21 years; SD = 1.68). Results Increases in cyberbullying perpetration and toxic online disinhibition were positively related to cyberhate perpetration. Furthermore, cyberbullies reported more cyberhate perpetration when they reported higher levels of toxic online disinhibition and less frequent cyberhate perpetration when they reported lower levels of toxic online disinhibition. Conclusion The current study provides evidence of a possible link between cyberbullying and cyberhate perpetration, moderated by toxic online disinhibition. This suggests that, to be effective, prevention and intervention programmes should (i) consider the co-occurrence of varying forms of cyberaggression and (ii) consider potential effects of the online environment on aggressive online behaviour among young people.}, language = {en} } @article{WrightHongWachs2021, author = {Wright, Michelle F. and Hong, Jun Sung and Wachs, Sebastian}, title = {The relationship between parenting styles and relationally victimized during adolescence}, series = {Journal of familiy trauma, child custody \& child development}, volume = {18}, journal = {Journal of familiy trauma, child custody \& child development}, number = {2}, publisher = {Routledge, Taylor \& Francis Group}, address = {Philadelphia, PA}, issn = {2690-4586}, doi = {10.1080/26904586.2021.1918036}, pages = {93 -- 107}, year = {2021}, abstract = {The present study examined the moderating role of parents' victimization status during adolescence in the associations between parenting styles, depression, and anxiety among relationally victimized adolescents. There were 436 relationally victimized adolescents (M age = 13.26 years, SD = .56) included in this study, along with their parents (n = 436; M age = 47.01 years, SD = .83; 86\% mothers), from the Midwestern region of the United States (N = 872). Adolescents completed questionnaires on their experiences of relational victimization, depression, and anxiety, and perceptions of their parents' parenting styles. Their parents completed a questionnaire on their relational victimization status during adolescence. Findings from the study revealed that the relationships between the permissive parenting style, depression, and anxiety among relationally victimized adolescents were stronger when adolescents' parents were also victims of relational bullying during adolescence. These findings underscore the importance of considering parents' peer victimization history during adolescence.}, language = {en} } @misc{SeboldGarbusowNebeetal.2018, author = {Sebold, Miriam and Garbusow, Maria and Nebe, S. and Sundmacher, L. and Kuitunen-Paul, S{\"o}ren and Wittchen, H. U. and Smolka, M. and Zimmermann, U. and Rapp, Michael A. and Huys, Q. and Schlagenhauf, Florian and Heinz, Andreas}, title = {From goals to habits in alcohol dependence}, series = {European psychiatry : the journal of the Association of European Psychiatrists}, volume = {48}, journal = {European psychiatry : the journal of the Association of European Psychiatrists}, publisher = {Elsevier}, address = {Paris}, issn = {0924-9338}, pages = {S274 -- S274}, year = {2018}, language = {en} } @misc{WachsVazsonyiWrightetal.2020, author = {Wachs, Sebastian and Vazsonyi, Alexander T. and Wright, Michelle F. and Ksinan Jiskrova, Gabriela}, title = {Cross-National Associations Among Cyberbullying Victimization, Self-Esteem, and Internet Addiction}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {651}, issn = {1866-8364}, doi = {10.25932/publishup-47438}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-474382}, pages = {12}, year = {2020}, abstract = {The relationship among cyberbullying victimization, lower self-esteem, and internet addiction has been well-established. Yet, little research exists that explains the nature of these associations, and no previous work has considered the inability to identify or describe one's emotions, namely, alexithymia, as a potential mediator of these links. The present study sought to investigate the indirect effects of cyberbullying victimization on self-esteem and internet addiction, mediated by alexithymia. The sample consisted of 1,442 participants between 12 and 17 years (Mage = 14.17, SD = 1.38, 51.5\% male) from Germany, the Netherlands, and the United States. Results showed a direct relationship between cyberbullying victimization and self-esteem and an indirect association mediated by alexithymia in the Dutch sample. However, in the German and U.S. samples, only an indirect relationship via alexithymia, but not a direct effect of cyberbullying victimization on self-esteem, was found. Consistent across the three country samples, cyberbullying victimization and internet addiction were directly and also indirectly associated via alexithymia. In sum, findings indicate that alexithymia might help better understand which detrimental effects cyberbullying victimization has on adolescent psychological health. Thus, cyberbullying prevention programs should consider implementing elements that educate adolescents on the ability to identify and describe their own emotions.}, language = {en} } @misc{WrightWachs2019, author = {Wright, Michelle F. and Wachs, Sebastian}, title = {Does Peer Rejection Moderate the Associations among Cyberbullying Victimization, Depression, and Anxiety among Adolescents with Autism Spectrum Disorder?}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, doi = {10.25932/publishup-42726}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427266}, pages = {12}, year = {2019}, abstract = {While the consequences of cyberbullying victimization have received some attention in the literature, to date, little is known about the multiple types of strains in adolescents' lives, such as whether cyberbullying victimization and peer rejection increase their vulnerability to depression and anxiety. Even though some research found that adolescents with disabilities show higher risk for cyberbullying victimization, most research has focused on typically developing adolescents. Thus, the present study focused on examining the moderating effect of peer rejection in the relationships between cyberbullying victimization, depression, and anxiety among adolescents with autism spectrum disorder. There were 128 participants (89\% male; ages ranging from 11-16 years old) with autism spectrum disorder in the sixth, seventh, or eighth grade at 16 middle schools in the United States. Participants completed questionnaires on cyberbullying victimization, peer rejection, depression, and anxiety. Results revealed that cyberbullying victimization was associated positively with peer rejection, anxiety, and depression among adolescents with autism spectrum disorder. Further, peer rejection was linked positively with depression and anxiety. Peer rejection moderated the positive relationship between cyberbullying victimization and depression, but not anxiety. Implications for prevention programs and future research are discussed.}, language = {en} } @article{KasalBesirogluZorluetal.2021, author = {Kasal, Meltem and Besiroglu, Lutfullah and Zorlu, Nabi and Dikmeer, Nur and Bilge, Aslihan and Durmaz, Ercan and Polat, Serap and Gelal, Fazil and Rapp, Michael A. and Heinz, Andreas and Sebold, Miriam}, title = {Fronto-striatal structures related with model-based control as an endophenotype for obsessive-compulsive disorder}, series = {Scientific reports}, volume = {11}, journal = {Scientific reports}, number = {1}, publisher = {Springer Nature}, address = {[London]}, issn = {2045-2322}, doi = {10.1038/s41598-021-91179-2}, pages = {10}, year = {2021}, abstract = {Recent theories suggest a shift from model-based goal-directed to model-free habitual decision-making in obsessive-compulsive disorder (OCD). However, it is yet unclear, whether this shift in the decision process is heritable. We investigated 32 patients with OCD, 27 unaffected siblings (SIBs) and 31 healthy controls (HCs) using the two-step task. We computed behavioral and reaction time analyses and fitted a computational model to assess the balance between model-based and model-free control. 80 subjects also underwent structural imaging. We observed a significant ordered effect for the shift towards model-free control in the direction OCD>SIB>HC in our computational parameter of interest. However less directed analyses revealed no shift towards model-free control in OCDs. Nonetheless, we found evidence for reduced model-based control in OCDs compared to HCs and SIBs via 2nd stage reaction time analyses. In this measure SIBs also showed higher levels of model-based control than HCs. Across all subjects these effects were associated with the surface area of the left medial/right dorsolateral prefrontal cortex. Moreover, correlations between bilateral putamen/right caudate volumes and these effects varied as a function of group: they were negative in SIBs and OCDs, but positive in HCs. Associations between fronto-striatal regions and model-based reaction time effects point to a potential endophenotype for OCD.}, language = {en} } @article{WrightWachsHuang2020, author = {Wright, Michelle F. and Wachs, Sebastian and Huang, Zheng}, title = {Adolescents' Popularity-Motivated Aggression and Prosocial Behaviors: The Roles of Callous-Unemotional Traits and Social Status Insecurity}, series = {Frontiers in Psychology}, journal = {Frontiers in Psychology}, publisher = {Frontiers}, address = {Lausanne, Schweiz}, issn = {1664-1078}, doi = {10.3389/fpsyg.2021.606865}, pages = {1 -- 8}, year = {2020}, abstract = {As competition over peer status becomes intense during adolescence, some adolescents develop insecure feelings regarding their social standing among their peers (i.e., social status insecurity). These adolescents sometimes use aggression to defend or promote their status. The aim of this study was to examine the relationships among social status insecurity, callous-unemotional (CU) traits, and popularity-motivated aggression and prosocial behaviors among adolescents, while controlling for gender. Another purpose was to examine the potential moderating role of CU traits in these relationships. Participants were 1,047 (49.2\% girls; Mage = 12.44 years; age range from 11 to 14 years) in the 7th or 8th grades from a large Midwestern city. They completed questionnaires on social status insecurity, CU traits, and popularity-motivated relational aggression, physical aggression, cyberaggression, and prosocial behaviors. A structural regression model was conducted, with gender as a covariate. The model had adequate fit. Social status insecurity was associated positively with callousness, unemotional, and popularity-motivated aggression and related negatively to popularity-motivated prosocial behaviors. High social status insecurity was related to greater popularity-motivated aggression when adolescents had high callousness traits. The findings have implications for understanding the individual characteristics associated with social status insecurity.}, language = {en} } @article{WrightWachs2022, author = {Wright, Michelle F. and Wachs, Sebastian}, title = {Self-isolation practices and perceived social support from friends}, series = {European journal of developmental psychology}, volume = {20}, journal = {European journal of developmental psychology}, number = {4}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {1740-5629}, doi = {10.1080/17405629.2022.2146090}, pages = {635 -- 648}, year = {2022}, abstract = {The purpose of the present study was to investigate the moderating effect of perceived social support from friends in the associations between self-isolation practices during the COVID-19 pandemic and adolescents' mental health (i.e., depression, subjective health complaints, self-harm), measured six months later (Time 2). Participants were 1,567 7(th) and 8(th) graders (51\% female; 51\% white; M age = 13.67) from the United States. They completed questionnaires on perceived social support from friends, depression, subjective health complaints, and self-harm at Time 1, and self-isolation practices during COVID-19, depression, subjective health complaints, and self-harm at Time 2. The findings revealed that self-isolation practices during COVID-19 was related positively to Time 1 perceived social support from friends, and negatively to Time 2 depression, subjective health complaints, and self-harm, while accounting for Time 1 mental health outcomes. Higher perceived social support from friends at Time 1 buffered against the negative impacts on adolescents' mental health outcomes at Time 2 when they practiced greater self-isolation during COVID-19, while lower perceived social support at Time 1 had the opposite effects on Time 2 mental health outcomes.}, language = {en} } @misc{HeinzKlugeRapp2016, author = {Heinz, Andreas and Kluge, U. and Rapp, Michael A.}, title = {Heritability of living in deprived neighbourhoods}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-103770}, pages = {1}, year = {2016}, language = {en} } @inproceedings{HeinzKlugeSchoulerOcaketal.2015, author = {Heinz, Andreas and Kluge, U. and Schouler-Ocak, M. and Rapp, Michael A.}, title = {Biological Effects of Social Exclusion}, series = {European psychiatry : the journal of the Association of European Psychiatrists}, volume = {30}, booktitle = {European psychiatry : the journal of the Association of European Psychiatrists}, publisher = {Elsevier}, address = {Paris}, issn = {0924-9338}, pages = {1}, year = {2015}, abstract = {Timing and magnitude of surface uplift are key to understanding the impact of crustal deformation and topographic growth on atmospheric circulation, environmental conditions, and surface processes. Uplift of the East African Plateau is linked to mantle processes, but paleoaltimetry data are too scarce to constrain plateau evolution and subsequent vertical motions associated with rifting. Here, we assess the paleotopographic implications of a beaked whale fossil (Ziphiidae) from the Turkana region of Kenya found 740 km inland from the present-day coastline of the Indian Ocean at an elevation of 620 m. The specimen is similar to 17 My old and represents the oldest derived beaked whale known, consistent with molecular estimates of the emergence of modern straptoothed whales (Mesoplodon). The whale traveled from the Indian Ocean inland along an eastward-directed drainage system controlled by the Cretaceous Anza Graben and was stranded slightly above sea level. Surface uplift from near sea level coincides with paleoclimatic change from a humid environment to highly variable and much drier conditions, which altered biotic communities and drove evolution in east Africa, including that of primates.}, language = {en} } @misc{WachsGoerzigWrightetal.2020, author = {Wachs, Sebastian and G{\"o}rzig, Anke and Wright, Michelle F. and Schubarth, Wilfried and Bilz, Ludwig}, title = {Associations among Adolescents' Relationships with Parents, Peers, and Teachers, Self-Efficacy, and Willingness to Intervene in Bullying}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {603}, issn = {1866-8364}, doi = {10.25932/publishup-44545}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-445458}, pages = {18}, year = {2020}, abstract = {We applied the Social Cognitive Theory to investigate whether parent-child relationships, bullying victimization, and teacher-student relationships are directly as well as indirectly via self-efficacy in social conflicts associated with adolescents' willingness to intervene in a bullying incident. There were 2071 (51.3\% male) adolescents between the ages of 12 and 17 from 24 schools in Germany who participated in this study. A mediation test using structural equation modeling revealed that parent-child relationships, bullying victimization, and teacher-student relationships were directly related to adolescents' self-efficacy in social conflicts. Further, teacher-student relationships and bullying victimization were directly associated with adolescents' willingness to intervene in bullying. Finally, relationships with parents, peers and teachers were indirectly related to higher levels of students' willingness to intervene in bullying situations due to self-efficacy in social conflicts. Thus, our analysis confirms the general assumptions of Social Cognitive Theory and the usefulness of applying its approach to social conflicts such as bullying situations.}, language = {en} } @misc{WrightWachs2019, author = {Wright, Michelle F. and Wachs, Sebastian}, title = {Adolescents' Psychological Consequences and Cyber Victimization}, series = {Postprints der Universit{\"a}t Potsdam Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam Humanwissenschaftliche Reihe}, number = {578}, issn = {1866-8364}, doi = {10.25932/publishup-43786}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-437868}, pages = {11}, year = {2019}, abstract = {Cyber victimization research reveals various personal and contextual correlations and negative consequences associated with this experience. Despite increasing attention on cyber victimization, few studies have examined such experiences among ethnic minority adolescents. The purpose of the present study was to examine the moderating effect of ethnicity in the longitudinal associations among cyber victimization, school-belongingness, and psychological consequences (i.e., depression, loneliness, anxiety). These associations were investigated among 416 Latinx and white adolescents (46\% female; M age = 13.89, SD = 0.41) from one middle school in the United States. They answered questionnaires on cyber victimization, school belongingness, depression, loneliness, and anxiety in the 7th grade (Time 1). One year later, in the 8th grade (Time 2), they completed questionnaires on depression, loneliness, and anxiety. Low levels of school-belongingness strengthened the positive relationships between cyber victimization and Time 2 depression and anxiety, especially among Latinx adolescents. The positive association between cyber victimization and Time 2 loneliness was strengthened for low levels of school-belongingness for all adolescents. These findings may indicate that cyber victimization threatens adolescents' school-belongingness, which has implications for their emotional adjustment. Such findings underscore the importance of considering diverse populations when examining cyber victimization.}, language = {en} } @article{BauerBanaschewskiHeinzetal.2016, author = {Bauer, M. and Banaschewski, Tobias and Heinz, Andreas and Kamp-Becker, I. and Meyer-Lindenberg, A. and Padberg, F. and Rapp, Michael A. and Rupprecht, R. and Schneider, F. and Schulze, T. G. and Wittchen, Hans-Ulrich}, title = {The German Research Network for mental Disorders}, series = {Der Nervenarzt : Organ der Deutschen Gesellschaft f{\~A}¼r Psychiatrie, Psychotherapie und Nervenheilkunde ; Mitteilungsblatt der Deutschen Gesellschaft f{\~A}¼r Neurologie}, volume = {87}, journal = {Der Nervenarzt : Organ der Deutschen Gesellschaft f{\~A}¼r Psychiatrie, Psychotherapie und Nervenheilkunde ; Mitteilungsblatt der Deutschen Gesellschaft f{\~A}¼r Neurologie}, publisher = {Springer}, address = {New York}, issn = {0028-2804}, doi = {10.1007/s00115-016-0169-y}, pages = {989 -- 1010}, year = {2016}, abstract = {Mental disorders are among the greatest medical and social challenges facing us. They can occur at all stages of life and are among the most important commonly occurring diseases. In Germany 28 \% of the population suffer from a mental disorder every year, while the lifetime risk of suffering from a mental disorder is almost 50 \%. Mental disorders cause great suffering for those affected and their social network. Quantitatively speaking, they can be considered to be among those diseases creating the greatest burden for society due to reduced productivity, absence from work and premature retirement. The Federal Ministry of Education and Research is funding a new research network from 2015 to 2019 with up to 35 million euros to investigate mental disorders in order to devise and develop better therapeutic measures and strategies for this population by means of basic and translational clinical research. This is the result of a competitive call for research proposals entitled research network for mental diseases. It is a nationwide network of nine consortia with up to ten psychiatric and clinical psychology partner institutions from largely university-based research facilities for adults and/or children and adolescents. Furthermore, three cross-consortia platform projects will seek to identify shared causes of diseases and new diagnostic modalities for anxiety disorders, attention deficit hyperactivity disorders (ADHS), autism, bipolar disorders, depression, schizophrenia and psychotic disorders as well as substance-related and addictive disorders. The spectrum of therapeutic approaches to be examined ranges from innovative pharmacological and psychotherapeutic treatment to novel brain stimulation procedures. In light of the enormous burden such diseases represent for society as a whole, a sustainable improvement in the financial support for those researching mental disorders seems essential. This network aims to become a nucleus for long overdue and sustained support for a German center for mental disorders.}, language = {de} } @article{WachsWrightSittichaietal.2019, author = {Wachs, Sebastian and Wright, Michelle F. and Sittichai, Ruthaychonnee and Singh, Ritu and Biswal, Ramakrishna and Kim, Eun-mee and Yang, Soeun and G{\´a}mez-Guadix, Manuel and Almendros, Carmen and Flora, Katerina and Daskalou, Vassiliki and Maziridou, Evdoxia}, title = {Associations between witnessing and perpetrating online hate in eight countries}, series = {International Journal of Environmental Research and Public Health}, volume = {16}, journal = {International Journal of Environmental Research and Public Health}, number = {20}, publisher = {MDPI}, address = {Basel}, issn = {1660-4601}, doi = {10.3390/ijerph16203992}, pages = {13}, year = {2019}, abstract = {Online hate is a topic that has received considerable interest lately, as online hate represents a risk to self-determination and peaceful coexistence in societies around the globe. However, not much is known about the explanations for adolescents posting or forwarding hateful online material or how adolescents cope with this newly emerging online risk. Thus, we sought to better understand the relationship between a bystander to and perpetrator of online hate, and the moderating effects of problem-focused coping strategies (e.g., assertive, technical coping) within this relationship. Self-report questionnaires on witnessing and committing online hate and assertive and technical coping were completed by 6829 adolescents between 12 and 18 years of age from eight countries. The results showed that increases in witnessing online hate were positively related to being a perpetrator of online hate. Assertive and technical coping strategies were negatively related with perpetrating online hate. Bystanders of online hate reported fewer instances of perpetrating online hate when they reported higher levels of assertive and technical coping strategies, and more frequent instances of perpetrating online hate when they reported lower levels of assertive and technical coping strategies. In conclusion, our findings suggest that, if effective, prevention and intervention programs that target online hate should consider educating young people about problem-focused coping strategies, self-assertiveness, and media skills. Implications for future research are discussed.}, language = {en} } @article{WrightWachs2019, author = {Wright, Michelle F. and Wachs, Sebastian}, title = {Does Peer Rejection Moderate the Associations among Cyberbullying Victimization, Depression, and Anxiety among Adolescents with Autism Spectrum Disorder?}, series = {Children}, volume = {6}, journal = {Children}, publisher = {MDPI}, address = {Basel}, issn = {2227-9067}, doi = {10.3390/children6030041}, pages = {12}, year = {2019}, abstract = {While the consequences of cyberbullying victimization have received some attention in the literature, to date, little is known about the multiple types of strains in adolescents' lives, such as whether cyberbullying victimization and peer rejection increase their vulnerability to depression and anxiety. Even though some research found that adolescents with disabilities show higher risk for cyberbullying victimization, most research has focused on typically developing adolescents. Thus, the present study focused on examining the moderating effect of peer rejection in the relationships between cyberbullying victimization, depression, and anxiety among adolescents with autism spectrum disorder. There were 128 participants (89\% male; ages ranging from 11-16 years old) with autism spectrum disorder in the sixth, seventh, or eighth grade at 16 middle schools in the United States. Participants completed questionnaires on cyberbullying victimization, peer rejection, depression, and anxiety. Results revealed that cyberbullying victimization was associated positively with peer rejection, anxiety, and depression among adolescents with autism spectrum disorder. Further, peer rejection was linked positively with depression and anxiety. Peer rejection moderated the positive relationship between cyberbullying victimization and depression, but not anxiety. Implications for prevention programs and future research are discussed.}, language = {en} } @misc{HeinzKlugeRapp2016, author = {Heinz, Andreas and Kluge, U. and Rapp, Michael A.}, title = {Heritability of living in deprived neighbourhoods}, series = {Translational Psychiatry}, volume = {6}, journal = {Translational Psychiatry}, publisher = {Nature Publ. Group}, address = {New York}, issn = {2158-3188}, doi = {10.1038/tp.2016.215}, pages = {1}, year = {2016}, language = {en} } @article{SommerGarbusowJuengeretal.2017, author = {Sommer, C. and Garbusow, Maria and Juenger, E. and Pooseh, S. and Bernhardt, Nadine and Birkenstock, J. and Schad, Daniel and Jabs, B. and Gloeckler, T. and Huys, Quentin J. M. and Heinz, Andreas and Smolka, Michael N. and Zimmermann, Ulrich S.}, title = {Strong seduction: impulsivity and the impact of contextual cues on instrumental behavior in alcohol dependence}, series = {Translational Psychiatry}, volume = {7}, journal = {Translational Psychiatry}, publisher = {Nature Publ. Group}, address = {New York}, issn = {2158-3188}, doi = {10.1038/tp.2017.158}, pages = {1209 -- 1222}, year = {2017}, abstract = {Alcohol-related cues acquire incentive salience through Pavlovian conditioning and then can markedly affect instrumental behavior of alcohol-dependent patients to promote relapse. However, it is unclear whether similar effects occur with alcohol-unrelated cues. We tested 116 early-abstinent alcohol-dependent patients and 91 healthy controls who completed a delay discounting task to assess choice impulsivity, and a Pavlovian-to-instrumental transfer (PIT) paradigm employing both alcohol-unrelated and alcohol-related stimuli. To modify instrumental choice behavior, we tiled the background of the computer screen either with conditioned stimuli (CS) previously generated by pairing abstract pictures with pictures indicating monetary gains or losses, or with pictures displaying alcohol or water beverages. CS paired to money gains and losses affected instrumental choices differently. This PIT effect was significantly more pronounced in patients compared to controls, and the group difference was mainly driven by highly impulsive patients. The PIT effect was particularly strong in trials in which the instrumental stimulus required inhibition of instrumental response behavior and the background CS was associated to monetary gains. Under that condition, patients performed inappropriate approach behavior, contrary to their previously formed behavioral intention. Surprisingly, the effect of alcohol and water pictures as background stimuli resembled that of aversive and appetitive CS, respectively. These findings suggest that positively valenced background CS can provoke dysfunctional instrumental approach behavior in impulsive alcohol-dependent patients. Consequently, in real life they might be easily seduced by environmental cues to engage in actions thwarting their long-term goals. Such behaviors may include, but are not limited to, approaching alcohol.}, language = {en} } @article{ZechReichertEbnerPriemeretal.2022, author = {Zech, Hilmar G. and Reichert, Markus and Ebner-Priemer, Ulrich W. and Tost, Heike and Rapp, Michael A. and Heinz, Andreas and Dolan, Raymond J. and Smolka, Michael N. and Deserno, Lorenz}, title = {Mobile data collection of cognitive-behavioral tasks in substance use disorders: Where are we now?}, series = {Neuropsychobiology}, volume = {81}, journal = {Neuropsychobiology}, number = {5}, publisher = {Karger}, address = {Basel}, issn = {0302-282X}, doi = {10.1159/000523697}, pages = {438 -- 450}, year = {2022}, abstract = {Introduction: Over the last decades, our understanding of the cognitive, motivational, and neural processes involved in addictive behavior has increased enormously. A plethora of laboratory-based and cross-sectional studies has linked cognitive-behavioral measures to between-subject differences in drinking behavior. However, such laboratory-based studies inevitably suffer from small sample sizes and the inability to link temporal fluctuations in task measures to fluctuations in real-life substance use. To overcome these problems, several existing behavioral tasks have been transferred to smartphones to allow studying cognition in the field. Method: In this narrative review, we first summarize studies that used existing behavioral tasks in the laboratory and self-reports of substance use with ecological momentary assessment (EMA) in the field. Next, we review studies on psychometric properties of smartphone-based behavioral tasks. Finally, we review studies that used both smartphone-based tasks and self-reports with EMA in the field. Results: Overall, studies were scarce and heterogenous both in tasks and in study outcomes. Nevertheless, existing findings are promising and point toward several methodological recommendations: concerning psychometrics, studies show that - although more systematic studies are necessary - task validity and reliability can be improved, for example, by analyzing several measurement sessions at once rather than analyzing sessions separately. Studies that use tasks in the field, moreover, show that power can be improved by choosing sampling schemes that combine time-based with event-based sampling, rather than relying on time-based sampling alone. Increasing sampling frequency can further increase power. However, as this also increases the burden to participants, more research is necessary to determine the ideal sampling frequency for each task. Conclusion: Although more research is necessary to systematically study both the psychometrics of smartphone-based tasks and the frequency at which task measures fluctuate, existing studies are promising and reveal important methodological recommendations useful for researchers interested in implementing behavioral tasks in EMA studies.}, language = {en} } @article{WachsBilzFischeretal.2018, author = {Wachs, Sebastian and Bilz, Ludwig and Fischer, Saskia M. and Schubarth, Wilfried and Wright, Michelle F.}, title = {Students' Willingness to Intervene in Bullying}, series = {International journal of environmental research and public health : IJERPH}, volume = {15}, journal = {International journal of environmental research and public health : IJERPH}, publisher = {MDPI}, address = {Basel}, issn = {1660-4601}, doi = {10.3390/ijerph15112577}, pages = {11}, year = {2018}, abstract = {Although school climate and self-efficacy have received some attention in the literature, as correlates of students' willingness to intervene in bullying, to date, very little is known about the potential mediating role of self-efficacy in the relationship between classroom climate and students' willingness to intervene in bullying. To this end, the present study analyzes whether the relationship between classroom cohesion (as one facet of classroom climate) and students' willingness to intervene in bullying situations is mediated by self-efficacy in social conflicts. This study is based on a representative stratified random sample of two thousand and seventy-one students (51.3\% male), between the ages of twelve and seventeen, from twenty-four schools in Germany. Results showed that between 43\% and 48\% of students reported that they would not intervene in bullying. A mediation test using the structural equation modeling framework revealed that classroom cohesion and self-efficacy in social conflicts were directly associated with students' willingness to intervene in bullying situations. Furthermore, classroom cohesion was indirectly associated with higher levels of students' willingness to intervene in bullying situations, due to self-efficacy in social conflicts. We thus conclude that: (1) It is crucial to increase students' willingness to intervene in bullying; (2) efforts to increase students' willingness to intervene in bullying should promote students' confidence in dealing with social conflicts and interpersonal relationships; and (3) self-efficacy plays an important role in understanding the relationship between classroom cohesion and students' willingness to intervene in bullying. Recommendations are provided to help increase adolescents' willingness to intervene in bullying and for future research.}, language = {en} } @article{WachsGoerzigWrightetal.2020, author = {Wachs, Sebastian and G{\"o}rzig, Anke and Wright, Michelle F. and Schubarth, Wilfried and Bilz, Ludwig}, title = {Associations among Adolescents' Relationships with Parents, Peers, and Teachers, Self-Efficacy, and Willingness to Intervene in Bullying}, series = {International Journal of Environmental Research and Public Health}, volume = {17}, journal = {International Journal of Environmental Research and Public Health}, number = {2}, publisher = {MDPI AG}, address = {Basel}, issn = {1660-4601}, doi = {10.3390/ijerph17020420}, pages = {16}, year = {2020}, abstract = {We applied the Social Cognitive Theory to investigate whether parent-child relationships, bullying victimization, and teacher-student relationships are directly as well as indirectly via self-efficacy in social conflicts associated with adolescents' willingness to intervene in a bullying incident. There were 2071 (51.3\% male) adolescents between the ages of 12 and 17 from 24 schools in Germany who participated in this study. A mediation test using structural equation modeling revealed that parent-child relationships, bullying victimization, and teacher-student relationships were directly related to adolescents' self-efficacy in social conflicts. Further, teacher-student relationships and bullying victimization were directly associated with adolescents' willingness to intervene in bullying. Finally, relationships with parents, peers and teachers were indirectly related to higher levels of students' willingness to intervene in bullying situations due to self-efficacy in social conflicts. Thus, our analysis confirms the general assumptions of Social Cognitive Theory and the usefulness of applying its approach to social conflicts such as bullying situations.}, language = {en} } @article{BilzStegerFischeretal.2016, author = {Bilz, Ludwig and Steger, Jette and Fischer, Saskia M. and Schubarth, Wilfried and Kunze, Ulrike}, title = {Is this already Violence? On the Importance of the Violence of Teachers on how to Deal with Bullying and the Actions of Pupils}, series = {Zeitschrift f{\~A}¼r P{\~A}\idagogik}, volume = {62}, journal = {Zeitschrift f{\~A}¼r P{\~A}\idagogik}, publisher = {Beltz}, address = {Weinheim}, issn = {0044-3247}, pages = {841 -- 860}, year = {2016}, language = {de} } @article{WachsWettsteinBilzetal.2022, author = {Wachs, Sebastian and Wettstein, Alexander and Bilz, Ludwig and Gamez-Guadix, Manuel}, title = {Motivos del discurso de odio en la adolescencia y su relaci{\´o}n con las normas sociales}, series = {Comunicar : revista cient{\´i}fica de comunicaci{\´o}n y educaci{\´o}n}, volume = {30}, journal = {Comunicar : revista cient{\´i}fica de comunicaci{\´o}n y educaci{\´o}n}, number = {71}, publisher = {Grupo Comunicar}, address = {Huelva}, issn = {1134-3478}, doi = {10.3916/C71-2022-01}, pages = {9 -- 20}, year = {2022}, abstract = {Hate speech has become a widespread phenomenon, however, it remains largely unclear why adolescents engage in it and which factors are associated with their motivations for perpetrating hate speech. To this end, we developed the multidimensional "Motivations for Hate Speech Perpetration Scale" (MHATE) and evaluated the psychometric properties. We also explored the associations between social norms and adolescents' motivations for hate speech perpetration. The sample consisted of 346 adolescents from Switzerland (54.6\% boys; Mage=14; SD=0.96) who reported engagement in hate speech as perpetrators. The analyses revealed good psychometric properties for the MHATE, including good internal consistency. The most frequently endorsed subscale was revenge, followed by ideology, group conformity, status enhancement, exhilaration, and power. The results also showed that descriptive norms and peer pressure were related to a wide range of different motivations for perpetrating hate speech. Injunctive norms, however, were only associated with power. In conclusion, findings indicate that hate speech fulfills various functions. We argue that knowing the specific motivations that underlie hate speech could help us derive individually tailored prevention strategies (e.g., anger management, promoting an inclusive classroom climate). Furthermore, we suggest that practitioners working in the field of hate speech prevention give special attention to social norms surrounding adolescents.}, language = {es} } @article{WachsWright2019, author = {Wachs, Sebastian and Wright, Michelle F.}, title = {The Moderation of online disinhibition and sex on the relationship between online hate victimization and perpetration}, series = {Cyberpsychology, behavior and social networking}, volume = {22}, journal = {Cyberpsychology, behavior and social networking}, number = {5}, publisher = {Liebert}, address = {New Rochelle}, issn = {2152-2715}, doi = {10.1089/cyber.2018.0551}, pages = {300 -- 306}, year = {2019}, abstract = {Online hatred based on attributes, such as origin, race, gender, religion, or sexual orientation, has become a rising public concern across the world. Past research on aggressive behavior suggests strong associations between victimization and perpetration and that toxic online disinhibition and sex might influence this relationship. However, no study investigated both the relationship between online hate victimization and perpetration and the potential moderation effects of toxic online disinhibition on this relationship. To this end, the present study was conducted. The sample consists of 1,480 7th to 10th graders from Germany. Results revealed positive associations between online hate victimization and perpetration. Furthermore, the results support the idea that toxic online disinhibition and sex, by way of moderator effects, affect the relationship between online hate victimization and perpetration. Victims of online hate reported more online hate perpetration when they reported higher levels of online disinhibition and less frequent online hate perpetration when they reported lower levels of toxic online disinhibition. Additionally, the relationship between online hate victimization and perpetration was significantly greater among boys than among girls. Taken together, our results extend previous findings to online hate involvement among adolescents and substantiate the importance to conduct more research on online hate. In addition, our findings highlight the need for prevention and intervention programs that help adolescents deal with the emerging issue of online hate.}, language = {en} } @article{SliusarenkoVitaliSposinietal.2019, author = {Sliusarenko, Oleksii Yu and Vitali, Silvia and Sposini, Vittoria and Paradisi, Paolo and Chechkin, Aleksei and Castellani, Gastone and Pagnini, Gianni}, title = {Finite-energy Levy-type motion through heterogeneous ensemble of Brownian particles}, series = {Journal of physics : A, Mathematical and theoretical}, volume = {52}, journal = {Journal of physics : A, Mathematical and theoretical}, number = {9}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {1751-8113}, doi = {10.1088/1751-8121/aafe90}, pages = {27}, year = {2019}, abstract = {Complex systems are known to display anomalous diffusion, whose signature is a space/time scaling x similar to t(delta) with delta not equal 1/2 in the probability density function (PDF). Anomalous diffusion can emerge jointly with both Gaussian, e.g. fractional Brownian motion, and power-law decaying distributions, e.g. Levy Flights or Levy Walks (LWs). Levy flights get anomalous scaling, but, being jumps of any size allowed even at short times, have infinite position variance, infinite energy and discontinuous paths. LWs, which are based on random trapping events, overcome these limitations: they resemble a Levy-type power-law distribution that is truncated in the large displacement range and have finite moments, finite energy and, even with discontinuous velocity, they are continuous. However, LWs do not take into account the role of strong heterogeneity in many complex systems, such as biological transport in the crowded cell environment. In this work we propose and discuss a model describing a heterogeneous ensemble of Brownian particles (HEBP). Velocity of each single particle obeys a standard underdamped Langevin equation for the velocity, with linear friction term and additive Gaussian noise. Each particle is characterized by its own relaxation time and velocity diffusivity. We show that, for proper distributions of relaxation time and velocity diffusivity, the HEBP resembles some LW statistical features, in particular power-law decaying PDF, long-range correlations and anomalous diffusion, at the same time keeping finite position moments and finite energy. The main differences between the HEBP model and two different LWs are investigated, finding that, even when both velocity and position PDFs are similar, they differ in four main aspects: (i) LWs are biscaling, while HEBP is monoscaling; (ii) a transition from anomalous (delta = 1/2) to normal (delta = 1/2) diffusion in the long-time regime is seen in the HEBP and not in LWs; (iii) the power-law index of the position PDF and the space/time diffusion scaling are independent in the HEBP, while they both depend on the scaling of the interevent time PDF in LWs; (iv) at variance with LWs, our HEBP model obeys a fluctuation-dissipation theorem.}, language = {en} } @article{VillalbaKasadaZoccaratoetal.2022, author = {Villalba, Luis Alberto and Kasada, Minoru and Zoccarato, Luca and Wollrab, Sabine and Grossart, Hans Peter}, title = {Differing escape responses of the marine bacterium Marinobacter adhaerens in the presence of planktonic vs. surface-associated protist grazers}, series = {International journal of molecular sciences}, volume = {23}, journal = {International journal of molecular sciences}, number = {17}, publisher = {MDPI}, address = {Basel}, issn = {1661-6596}, doi = {10.3390/ijms231710082}, pages = {13}, year = {2022}, abstract = {Protist grazing pressure plays a major role in controlling aquatic bacterial populations, affecting energy flow through the microbial loop and biogeochemical cycles. Predator-escape mechanisms might play a crucial role in energy flow through the microbial loop, but are yet understudied. For example, some bacteria can use planktonic as well as surface-associated habitats, providing a potential escape mechanism to habitat-specific grazers. We investigated the escape response of the marine bacterium Marinobacter adhaerens in the presence of either planktonic (nanoflagellate: Cafeteria roenbergensis) or surface-associated (amoeba: Vannella anglica) protist predators, following population dynamics over time. In the presence of V. anglica, M. adhaerens cell density increased in the water, but decreased on solid surfaces, indicating an escape response towards the planktonic habitat. In contrast, the planktonic predator C. roenbergensis induced bacterial escape to the surface habitat. While C. roenbergensis cell numbers dropped substantially after a sharp initial increase, V. anglica exhibited a slow, but constant growth throughout the entire experiment. In the presence of C. roenbergensis, M. adhaerens rapidly formed cell clumps in the water habitat, which likely prevented consumption of the planktonic M. adhaerens by the flagellate, resulting in a strong decline in the predator population. Our results indicate an active escape of M. adhaerens via phenotypic plasticity (i.e., behavioral and morphological changes) against predator ingestion. This study highlights the potentially important role of behavioral escape mechanisms for community composition and energy flow in pelagic environments, especially with globally rising particle loads in aquatic systems through human activities and extreme weather events.}, language = {en} } @article{LunaKorup2022, author = {Luna, Lisa and Korup, Oliver}, title = {Seasonal landslide activity lags annual precipitation pattern in the Pacific Northwest}, series = {Geophysical research letters}, volume = {49}, journal = {Geophysical research letters}, number = {18}, publisher = {Wiley}, address = {Hoboken, NJ}, issn = {0094-8276}, doi = {10.1029/2022GL098506}, pages = {11}, year = {2022}, abstract = {Seasonal variations in landslide activity remain understudied compared to recent advances in landslide early warning at hourly to daily timescales. Here, we learn the seasonal pattern of monthly landslide activity in the Pacific Northwest from five heterogeneous landslide inventories with differing spatial and temporal coverage and reporting protocols combined in a Bayesian multi-level model. We find that landslide activity is distinctly seasonal, with credible increases in landslide intensity, inter-annual variability, and probability marking the onset of the landslide season in November. Peaks in landslide probability in January and intensity in February lag the annual peak in mean monthly precipitation and landslide activity is more variable in winter than in summer, when landslides are rare. For a given monthly rainfall, landslide intensity at the season peak in February is up to 10 times higher than at the onset in November, underlining the importance of antecedent seasonal hillslope conditions.}, language = {en} } @article{RosenwinkelLandgrafSchwanghartetal.2017, author = {Rosenwinkel, Swenja and Landgraf, Angela and Schwanghart, Wolfgang and Volkmer, Friedrich and Dzhumabaeva, Atyrgul and Merchel, Silke and Rugel, Georg and Preusser, Frank and Korup, Oliver}, title = {Late Pleistocene outburst floods from Issyk Kul, Kyrgyzstan?}, series = {Earth surface processes and landforms : the journal of the British Geomorphological Research Group}, volume = {42}, journal = {Earth surface processes and landforms : the journal of the British Geomorphological Research Group}, publisher = {Wiley}, address = {Hoboken}, issn = {0197-9337}, doi = {10.1002/esp.4109}, pages = {1535 -- 1548}, year = {2017}, language = {en} } @misc{ŚlęzakMetzlerMagdziarz2018, author = {Ślęzak, Jakub and Metzler, Ralf and Magdziarz, Marcin}, title = {Superstatistical generalised Langevin equation}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-409315}, pages = {25}, year = {2018}, abstract = {Recent advances in single particle tracking and supercomputing techniques demonstrate the emergence of normal or anomalous, viscoelastic diffusion in conjunction with non-Gaussian distributions in soft, biological, and active matter systems. We here formulate a stochastic model based on a generalised Langevin equation in which non-Gaussian shapes of the probability density function and normal or anomalous diffusion have a common origin, namely a random parametrisation of the stochastic force. We perform a detailed analysis demonstrating how various types of parameter distributions for the memory kernel result in exponential, power law, or power-log law tails of the memory functions. The studied system is also shown to exhibit a further unusual property: the velocity has a Gaussian one point probability density but non-Gaussian joint distributions. This behaviour is reflected in the relaxation from a Gaussian to a non-Gaussian distribution observed for the position variable. We show that our theoretical results are in excellent agreement with stochastic simulations.}, language = {en} } @misc{BurneckiWylomanskaChechkin2015, author = {Burnecki, Krzysztof and Wylomanska, Agnieszka and Chechkin, Aleksei}, title = {Discriminating between light- and heavy-tailed distributions with limit theorem}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {495}, issn = {1866-8372}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-408172}, pages = {23}, year = {2015}, abstract = {In this paper we propose an algorithm to distinguish between light- and heavy-tailed probability laws underlying random datasets. The idea of the algorithm, which is visual and easy to implement, is to check whether the underlying law belongs to the domain of attraction of the Gaussian or non-Gaussian stable distribution by examining its rate of convergence. The method allows to discriminate between stable and various non-stable distributions. The test allows to differentiate between distributions, which appear the same according to standard Kolmogorov-Smirnov test. In particular, it helps to distinguish between stable and Student's t probability laws as well as between the stable and tempered stable, the cases which are considered in the literature as very cumbersome. Finally, we illustrate the procedure on plasma data to identify cases with so-called L-H transition.}, language = {en} } @misc{KorzeniowskaBuehlerMauroetal.2017, author = {Korzeniowska, Karolina and B{\"u}hler, Yves and Mauro, Marty and Korup, Oliver}, title = {Regional snow-avalanche detection using object-based image analysis of near-infrared aerial imagery}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-403942}, pages = {14}, year = {2017}, abstract = {Snow avalanches are destructive mass movements in mountain regions that continue to claim lives and cause infrastructural damage and traffic detours. Given that avalanches often occur in remote and poorly accessible steep terrain, their detection and mapping is extensive and time consuming. Nonetheless, systematic avalanche detection over large areas could help to generate more complete and up-to-date inventories (cadastres) necessary for validating avalanche forecasting and hazard mapping. In this study, we focused on automatically detecting avalanches and classifying them into release zones, tracks, and run-out zones based on 0.25 m near-infrared (NIR) ADS80-SH92 aerial imagery using an object-based image analysis (OBIA) approach. Our algorithm takes into account the brightness, the normalised difference vegetation index (NDVI), the normalised difference water index (NDWI), and its standard deviation (SDNDWI) to distinguish avalanches from other land-surface elements. Using normalised parameters allows applying this method across large areas. We trained the method by analysing the properties of snow avalanches at three 4 km-2 areas near Davos, Switzerland. We compared the results with manually mapped avalanche polygons and obtained a user's accuracy of > 0.9 and a Cohen's kappa of 0.79-0.85. Testing the method for a larger area of 226.3 km-2, we estimated producer's and user's accuracies of 0.61 and 0.78, respectively, with a Cohen's kappa of 0.67. Detected avalanches that overlapped with reference data by > 80 \% occurred randomly throughout the testing area, showing that our method avoids overfitting. Our method has potential for large-scale avalanche mapping, although further investigations into other regions are desirable to verify the robustness of our selected thresholds and the transferability of the method.}, language = {en} } @misc{SchwanghartWorniHuggeletal.2016, author = {Schwanghart, Wolfgang and Worni, Raphael and Huggel, Christian and Stoffel, Markus and Korup, Oliver}, title = {Uncertainty in the Himalayan energy-water nexus}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-97136}, pages = {9}, year = {2016}, abstract = {Himalayan water resources attract a rapidly growing number of hydroelectric power projects (HPP) to satisfy Asia's soaring energy demands. Yet HPP operating or planned in steep, glacier-fed mountain rivers face hazards of glacial lake outburst floods (GLOFs) that can damage hydropower infrastructure, alter water and sediment yields, and compromise livelihoods downstream. Detailed appraisals of such GLOF hazards are limited to case studies, however, and a more comprehensive, systematic analysis remains elusive. To this end we estimate the regional exposure of 257 Himalayan HPP to GLOFs, using a flood-wave propagation model fed by Monte Carlo-derived outburst volumes of >2300 glacial lakes. We interpret the spread of thus modeled peak discharges as a predictive uncertainty that arises mainly from outburst volumes and dam-breach rates that are difficult to assess before dams fail. With 66\% of sampled HPP are on potential GLOF tracks, up to one third of these HPP could experience GLOF discharges well above local design floods, as hydropower development continues to seek higher sites closer to glacial lakes. We compute that this systematic push of HPP into headwaters effectively doubles the uncertainty about GLOF peak discharge in these locations. Peak discharges farther downstream, in contrast, are easier to predict because GLOF waves attenuate rapidly. Considering this systematic pattern of regional GLOF exposure might aid the site selection of future Himalayan HPP. Our method can augment, and help to regularly update, current hazard assessments, given that global warming is likely changing the number and size of Himalayan meltwater lakes.}, language = {en} } @misc{MeyerSchwanghartKorupetal.2015, author = {Meyer, Nele Kristin and Schwanghart, Wolfgang and Korup, Oliver and Nadim, F.}, title = {Roads at risk}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {519}, issn = {1866-8372}, doi = {10.25932/publishup-40958}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-409586}, pages = {11}, year = {2015}, abstract = {Globalisation and interregional exchange of people, goods, and services has boosted the importance of and reliance on all kinds of transport networks. The linear structure of road networks is especially sensitive to natural hazards. In southern Norway, steep topography and extreme weather events promote frequent traffic disruption caused by debris flows. Topographic susceptibility and trigger frequency maps serve as input into a hazard appraisal at the scale of first-order catchments to quantify the impact of debris flows on the road network in terms of a failure likelihood of each link connecting two network vertices, e.g. road junctions. We compute total additional traffic loads as a function of traffic volume and excess distance, i.e. the extra length of an alternative path connecting two previously disrupted network vertices using a shortest-path algorithm. Our risk metric of link failure is the total additional annual traffic load, expressed as vehicle kilometres, because of debris-flow-related road closures. We present two scenarios demonstrating the impact of debris flows on the road network and quantify the associated path-failure likelihood between major cities in southern Norway. The scenarios indicate that major routes crossing the central and north-western part of the study area are associated with high link-failure risk. Yet options for detours on major routes are manifold and incur only little additional costs provided that drivers are sufficiently well informed about road closures. Our risk estimates may be of importance to road network managers and transport companies relying on speedy delivery of services and goods.}, language = {en} } @misc{CherstvyMetzler2016, author = {Cherstvy, Andrey G. and Metzler, Ralf}, title = {Anomalous diffusion in time-fluctuating non-stationary diffusivity landscapes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-95901}, pages = {23840 -- 23852}, year = {2016}, abstract = {We investigate the ensemble and time averaged mean squared displacements for particle diffusion in a simple model for disordered media by assuming that the local diffusivity is both fluctuating in time and has a deterministic average growth or decay in time. In this study we compare computer simulations of the stochastic Langevin equation for this random diffusion process with analytical results. We explore the regimes of normal Brownian motion as well as anomalous diffusion in the sub- and superdiffusive regimes. We also consider effects of the inertial term on the particle motion. The investigation of the resulting diffusion is performed for unconfined and confined motion.}, language = {en} } @article{HeinzelRappFydrichetal.2017, author = {Heinzel, Stephan and Rapp, Michael A. and Fydrich, Thomas and Str{\"o}hle, Andreas and Teran, Christina and Kallies, Gunnar and Schwefel, Melanie and Heissel, Andreas}, title = {Neurobiological mechanisms of exercise and psychotherapy in depression}, series = {Clinical Trials}, volume = {15}, journal = {Clinical Trials}, number = {1}, publisher = {Sage Publ.}, address = {London}, issn = {1740-7745}, doi = {10.1177/1740774517729161}, pages = {53 -- 64}, year = {2017}, abstract = {Background/Aims: Even though cognitive behavioral therapy has become a relatively effective treatment for major depressive disorder and cognitive behavioral therapy-related changes of dysfunctional neural activations were shown in recent studies, remission rates still remain at an insufficient level. Therefore, the implementation of effective augmentation strategies is needed. In recent meta-analyses, exercise therapy (especially endurance exercise) was reported to be an effective intervention in major depressive disorder. Despite these findings, underlying mechanisms of the antidepressant effect of exercise especially in combination with cognitive behavioral therapy have rarely been studied to date and an investigation of its neural underpinnings is lacking. A better understanding of the psychological and neural mechanisms of exercise and cognitive behavioral therapy would be important for developing optimal treatment strategies in depression. The SPeED study (Sport/Exercise Therapy and Psychotherapyevaluating treatment Effects in Depressive patients) is a randomized controlled trial to investigate underlying physiological, neurobiological, and psychological mechanisms of the augmentation of cognitive behavioral therapy with endurance exercise. It is investigated if a preceding endurance exercise program will enhance the effect of a subsequent cognitive behavioral therapy. Methods: This study will include 105 patients diagnosed with a mild or moderate depressive episode according to the Diagnostic and Statistical Manual of Mental Disorders (4th ed.). The participants are randomized into one of three groups: a high-intensive or a low-intensive endurance exercise group or a waiting list control group. After the exercise program/waiting period, all patients receive an outpatient cognitive behavioral therapy treatment according to a standardized therapy manual. At four measurement points, major depressive disorder symptoms (Beck Depression Inventory, Hamilton Rating Scale for Depression), (neuro)biological measures (neural activations during working memory, monetary incentive delay task, and emotion regulation, as well as cortisol levels and brain-derived neurotrophic factor), neuropsychological test performance, and questionnaires (psychological needs, self-efficacy, and quality of life) are assessed. Results: In this article, we report the design of the SPeED study and refer to important methodological issues such as including both high- and low-intensity endurance exercise groups to allow the investigation of dose-response effects and physiological components of the therapy effects. Conclusion: The main aims of this research project are to study effects of endurance exercise and cognitive behavioral therapy on depressive symptoms and to investigate underlying physiological and neurobiological mechanisms of these effects. Results may provide important implications for the development of effective treatment strategies in major depressive disorder, specifically concerning the augmentation of cognitive behavioral therapy by endurance exercise.}, language = {en} } @article{VogelOzturkRiemeretal.2017, author = {Vogel, Kristin and Ozturk, Ugur and Riemer, Adrian and Laudan, Jonas and Sieg, Tobias and Wendi, Dadiyorto and Agarwal, Ankit and Roezer, Viktor and Korup, Oliver and Thieken, Annegret}, title = {Die Sturzflut von Braunsbach am 29. Mai 2016 - Entstehung, Ablauf und Sch{\"a}den eines „Jahrhundertereignisses"}, series = {Hydrologie und Wasserbewirtschaftung}, volume = {61}, journal = {Hydrologie und Wasserbewirtschaftung}, number = {3}, publisher = {Bundesanst. f{\"u}r Gew{\"a}sserkunde}, address = {Koblenz}, issn = {1439-1783}, doi = {10.5675/HyWa_2017,3_2}, pages = {163 -- 175}, year = {2017}, abstract = {Am Abend des 29. Mai 2016 wurde der Ort Braunsbach im Landkreis Schw{\"a}bisch-Hall (Baden-W{\"u}rttemberg) von einer Sturzflut getroffen, bei der mehrere H{\"a}user stark besch{\"a}digt oder zerst{\"o}rt wurden. Die Sturzflut war eine der Unwetterfolgen, die im Fr{\"u}hsommer 2016 vom Tiefdruckgebiet Elvira ausgel{\"o}st wurden. Der vorliegende Bericht ist der zweite Teil einer Doppelver{\"o}ffentlichung, welche die Ergebnisse zur Untersuchung des Sturzflutereignisses im Rahmen des DFG-Graduiertenkollegs "Naturgefahren und Risiken in einer sich ver{\"a}ndernden Welt" (NatRiskChange, GRK 2043/1) der Universit{\"a}t Potsdam pr{\"a}sentiert. W{\"a}hrend Teil 1 die meteorologischen und hydrologischen Ereignisse analysiert, fokussiert Teil 2 auf die geomorphologischen Prozesse und die verursachten Geb{\"a}udesch{\"a}den. Dazu wurden Ursprung und Ausmaß des w{\"a}hrend des Sturzflutereignisses mobilisierten und in den Ort getragenen Materials untersucht. Des Weiteren wurden zu 96 betroffenen Geb{\"a}uden Daten zum Schadensgrad sowie Prozess- und Geb{\"a}udecharakteristika aufgenommen und ausgewertet. Die Untersuchungen zeigen, dass bei der Betrachtung von Hochwassergef{\"a}hrdung die Ber{\"u}cksichtigung von Sturzfluten und ihrer speziellen Charakteristika, wie hoher Feststofftransport und sprunghaftes Verhalten insbesondere in bebautem Gel{\"a}nde, wesentlich ist, um effektive Schutzmaßnahmen ergreifen zu k{\"o}nnen.}, language = {de} } @article{BloetheMunackKorupetal.2014, author = {Bloethe, Jan H. and Munack, Henry and Korup, Oliver and Fuelling, Alexander and Garzanti, Eduardo and Resentini, Alberto and Kubik, Peter W.}, title = {Late Quaternary valley infill and dissection in the Indus River, western Tibetan Plateau margin}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {94}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2014.04.011}, pages = {102 -- 119}, year = {2014}, abstract = {The Indus, one of Earth's major rivers, drains large parts of the NW Himalaya and the Transhimalayan ranges that form part of the western Tibetan Plateau margin. In the western Himalayan syntaxis, where local topographic relief exceeds 7 km, the Indus has incised a steep bedrock gorge at rates of several mm yr(-1). Upstream, however, the upper Indus and its tributaries alternate between bedrock gorges and broad alluvial flats flanked by the Ladakh and Zanskar ranges. We review the late Quaternary valley history in this region with a focus on the confluence of the Indus and Zanskar Rivers, where vast alluvial terrace staircases and lake sediments record major episodes of aggradation and incision. New absolute dating of high-level fluvial terrace remnants using cosmogenic Be-10, optically and infrared stimulated luminescence (OSL, IRSL) indicates at least two phases of late Quaternary valley infilling. These phases commenced before similar to 200 ka and similar to 50-20 ka, judging from terrace treads stranded >150 m and similar to 30-40 m above modern river levels, respectively. Numerous stacks of lacustrine sediments that straddle the Indus River >200 km between the city of Leh and the confluence with the Shyok River share a distinct horizontal alignment. Constraints from IRSL samples of lacustrine sequences from the Leh-Spituk area reveal a protracted lake phase from >177 ka to 72 ka, locally accumulating >50-m thick deposits. In the absence of tectonic faulting, major lithological differences, and stream capture, we attribute the formation of this and other large lakes in the region to natural damming by large landslides, glaciers, and alluvial fans. The overall patchy landform age constraints from earlier studies can be reconciled by postulating a major deglacial control on sediment flux, valley infilling, and subsequent incision that has been modulated locally by backwater effects of natural damming. While comparison with Pleistocene monsoon proxies reveals no obvious correlation, a lateor post-glacial sediment pulse seems a more likely source of this widespread sedimentation that has partly buried the dissected bedrock topography. Overall, the long residence times of fluvial, alluvial and lacustrine deposits in the region (>500 ka) support previous studies, but remain striking given the dominantly steep slopes and deeply carved valleys that characterise this high-altitude mountain desert. Recalculated late Quaternary rates of fluvial bedrock incision in the Indus and Zanskar of 1.5 +/- 0.2 mm yr(-1) are at odds with the longevity of juxtaposed valley-fill deposits, unless a lack of decisive lateral fluvial erosion helps to preserve these late Pleistocene sedimentary archives. We conclude that alternating, similar to 10(4)-yr long, phases of massive infilling and incision have dominated the late Quaternary history of the Indus valley below the western Tibetan Plateau margin. (C) 2014 Elsevier Ltd. All rights reserved.}, language = {en} } @misc{FanScaringiKorupetal.2019, author = {Fan, Xuanmei and Scaringi, Gianvito and Korup, Oliver and West, A. Joshua and van Westen, Cees J. and Tanyas, Hakan and Hovius, Niels and Hales, Tristram C. and Jibson, Randall W. and Allstadt, Kate E. and Zhang, Limin and Evans, Stephen G. and Xu, Chong and Li, Gen and Pei, Xiangjun and Xu, Qiang and Huang, Runqiu}, title = {Earthquake-Induced Chains of Geologic Hazards}, series = {Reviews of geophysics}, volume = {57}, journal = {Reviews of geophysics}, number = {2}, publisher = {American Geophysical Union}, address = {Washington}, issn = {8755-1209}, doi = {10.1029/2018RG000626}, pages = {421 -- 503}, year = {2019}, abstract = {Large earthquakes initiate chains of surface processes that last much longer than the brief moments of strong shaking. Most moderate- and large-magnitude earthquakes trigger landslides, ranging from small failures in the soil cover to massive, devastating rock avalanches. Some landslides dam rivers and impound lakes, which can collapse days to centuries later, and flood mountain valleys for hundreds of kilometers downstream. Landslide deposits on slopes can remobilize during heavy rainfall and evolve into debris flows. Cracks and fractures can form and widen on mountain crests and flanks, promoting increased frequency of landslides that lasts for decades. More gradual impacts involve the flushing of excess debris downstream by rivers, which can generate bank erosion and floodplain accretion as well as channel avulsions that affect flooding frequency, settlements, ecosystems, and infrastructure. Ultimately, earthquake sequences and their geomorphic consequences alter mountain landscapes over both human and geologic time scales. Two recent events have attracted intense research into earthquake-induced landslides and their consequences: the magnitude M 7.6 Chi-Chi, Taiwan earthquake of 1999, and the M 7.9 Wenchuan, China earthquake of 2008. Using data and insights from these and several other earthquakes, we analyze how such events initiate processes that change mountain landscapes, highlight research gaps, and suggest pathways toward a more complete understanding of the seismic effects on the Earth's surface.}, language = {en} } @article{VogelKamitzHallahanetal.2018, author = {Vogel, Heike and Kamitz, Anne and Hallahan, Nicole and Lebek, Sandra and Schallschmidt, Tanja and Jonas, Wenke and J{\"a}hnert, Markus and Gottmann, Pascal and Zellner, Lisa and Kanzleiter, Timo and Damen, Mareike and Altenhofen, Delsi and Burkhardt, Ralph and Renner, Simone and Dahlhoff, Maik and Wolf, Eckhard and M{\"u}ller, Timo Dirk and Bl{\"u}her, Matthias and Joost, Hans-Georg and Chadt, Alexandra and Al-Hasani, Hadi and Sch{\"u}rmann, Annette}, title = {A collective diabetes cross in combination with a computational framework to dissect the genetics of human obesity and Type 2 diabetes}, series = {Human molecular genetics}, volume = {27}, journal = {Human molecular genetics}, number = {17}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0964-6906}, doi = {10.1093/hmg/ddy217}, pages = {3099 -- 3112}, year = {2018}, abstract = {To explore the genetic determinants of obesity and Type 2 diabetes (T2D), the German Center for Diabetes Research (DZD) conducted crossbreedings of the obese and diabetes-prone New Zealand Obese mouse strain with four different lean strains (B6, DBA, C3H, 129P2) that vary in their susceptibility to develop T2D. Genome-wide linkage analyses localized more than 290 quantitative trait loci (QTL) for obesity, 190 QTL for diabetes-related traits and 100 QTL for plasma metabolites in the out-cross populations. A computational framework was developed that allowed to refine critical regions and to nominate a small number of candidate genes by integrating reciprocal haplotype mapping and transcriptome data. The efficiency of the complex procedure was demonstrated for one obesity QTL. The genomic interval of 35 Mb with 502 annotated candidate genes was narrowed down to six candidates. Accordingly, congenic mice retained the obesity phenotype owing to an interval that contains three of the six candidate genes. Among these the phospholipase PLA2G4A exhibited an elevated expression in adipose tissue of obese human subjects and is therefore a critical regulator of the obesity locus. Together, our broad and complex approach demonstrates that combined- and comparative-cross analysis exhibits improved mapping resolution and represents a valid tool for the identification of disease genes.}, language = {en} } @article{SamprognaMohorThiekenKorup2021, author = {Samprogna Mohor, Guilherme and Thieken, Annegret and Korup, Oliver}, title = {Residential flood loss estimated from Bayesian multilevel models}, series = {Natural Hazards and Earth System Sciences}, volume = {21}, journal = {Natural Hazards and Earth System Sciences}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, issn = {2195-9269}, doi = {10.5194/nhess-21-1599-2021}, pages = {1599 -- 1614}, year = {2021}, abstract = {Models for the predictions of monetary losses from floods mainly blend data deemed to represent a single flood type and region. Moreover, these approaches largely ignore indicators of preparedness and how predictors may vary between regions and events, challenging the transferability of flood loss models. We use a flood loss database of 1812 German flood-affected households to explore how Bayesian multilevel models can estimate normalised flood damage stratified by event, region, or flood process type. Multilevel models acknowledge natural groups in the data and allow each group to learn from others. We obtain posterior estimates that differ between flood types, with credibly varying influences of water depth, contamination, duration, implementation of property-level precautionary measures, insurance, and previous flood experience; these influences overlap across most events or regions, however. We infer that the underlying damaging processes of distinct flood types deserve further attention. Each reported flood loss and affected region involved mixed flood types, likely explaining the uncertainty in the coefficients. Our results emphasise the need to consider flood types as an important step towards applying flood loss models elsewhere. We argue that failing to do so may unduly generalise the model and systematically bias loss estimations from empirical data.}, language = {en} } @article{ShinCherstvyMetzler2014, author = {Shin, Jaeoh and Cherstvy, Andrey G. and Metzler, Ralf}, title = {Kinetics of polymer looping with macromolecular crowding: effects of volume fraction and crowder size}, series = {Soft Matter}, journal = {Soft Matter}, editor = {Metzler, Ralf}, publisher = {The Royal Society of Chemistry}, address = {Cambridge}, issn = {1744-683X}, pages = {472 -- 488}, year = {2014}, abstract = {The looping of polymers such as DNA is a fundamental process in the molecular biology of living cells, whose interior is characterised by a high degree of molecular crowding. We here investigate in detail the looping dynamics of flexible polymer chains in the presence of different degrees of crowding. From the analysis of the looping-unlooping rates and the looping probabilities of the chain ends we show that the presence of small crowders typically slows down the chain dynamics but larger crowders may in fact facilitate the looping. We rationalise these non-trivial and often counterintuitive effects of the crowder size on the looping kinetics in terms of an effective solution viscosity and standard excluded volume. It is shown that for small crowders the effect of an increased viscosity dominates, while for big crowders we argue that confinement effects (caging) prevail. The tradeoff between both trends can thus result in the impediment or facilitation of polymer looping, depending on the crowder size. We also examine how the crowding volume fraction, chain length, and the attraction strength of the contact groups of the polymer chain affect the looping kinetics and hairpin formation dynamics. Our results are relevant for DNA looping in the absence and presence of protein mediation, DNA hairpin formation, RNA folding, and the folding of polypeptide chains under biologically relevant high-crowding conditions.}, language = {en} } @article{PalyulinChechkinMetzler2014, author = {Palyulin, Vladimir V. and Chechkin, Aleksei and Metzler, Ralf}, title = {Levy flights do not always optimize random blind search for sparse targets}, series = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {111}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, number = {8}, publisher = {National Acad. of Sciences}, address = {Washington}, issn = {0027-8424}, doi = {10.1073/pnas.1320424111}, pages = {2931 -- 2936}, year = {2014}, abstract = {It is generally believed that random search processes based on scale-free, Levy stable jump length distributions (Levy flights) optimize the search for sparse targets. Here we show that this popular search advantage is less universal than commonly assumed. We study the efficiency of a minimalist search model based on Levy flights in the absence and presence of an external drift (underwater current, atmospheric wind, a preference of the walker owing to prior experience, or a general bias in an abstract search space) based on two different optimization criteria with respect to minimal search time and search reliability (cumulative arrival probability). Although Levy flights turn out to be efficient search processes when the target is far from the starting point, or when relative to the starting point the target is upstream, we show that for close targets and for downstream target positioning regular Brownian motion turns out to be the advantageous search strategy. Contrary to claims that Levy flights with a critical exponent alpha = 1 are optimal for the search of sparse targets in different settings, based on our optimization parameters the optimal a may range in the entire interval (1, 2) and especially include Brownian motion as the overall most efficient search strategy.}, language = {en} } @misc{GhoshCherstvyMetzler2014, author = {Ghosh, Surya K. and Cherstvy, Andrey G. and Metzler, Ralf}, title = {Non-universal tracer diffusion in crowded media of non-inert obstacles}, publisher = {The Royal Society of Chemistry}, address = {Cambridge}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-77128}, pages = {1847 -- 1858}, year = {2014}, abstract = {We study the diffusion of a tracer particle, which moves in continuum space between a lattice of excluded volume, immobile non-inert obstacles. In particular, we analyse how the strength of the tracer-obstacle interactions and the volume occupancy of the crowders alter the diffusive motion of the tracer. From the details of partitioning of the tracer diffusion modes between trapping states when bound to obstacles and bulk diffusion, we examine the degree of localisation of the tracer in the lattice of crowders. We study the properties of the tracer diffusion in terms of the ensemble and time averaged mean squared displacements, the trapping time distributions, the amplitude variation of the time averaged mean squared displacements, and the non-Gaussianity parameter of the diffusing tracer. We conclude that tracer-obstacle adsorption and binding triggers a transient anomalous diffusion. From a very narrow spread of recorded individual time averaged trajectories we exclude continuous type random walk processes as the underlying physical model of the tracer diffusion in our system. For moderate tracer-crowder attraction the motion is found to be fully ergodic, while at stronger attraction strength a transient disparity between ensemble and time averaged mean squared displacements occurs. We also put our results into perspective with findings from experimental single-particle tracking and simulations of the diffusion of tagged tracers in dense crowded suspensions. Our results have implications for the diffusion, transport, and spreading of chemical components in highly crowded environments inside living cells and other structured liquids.}, language = {en} } @article{vonSpechtOeztuerkVehetal.2019, author = {von Specht, Sebastian and {\"O}zt{\"u}rk, Ugur and Veh, Georg and Cotton, Fabrice and Korup, Oliver}, title = {Effects of finite source rupture on landslide triggering}, series = {Solid earth}, volume = {10}, journal = {Solid earth}, number = {2}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1869-9510}, doi = {10.5194/se-10-463-2019}, pages = {463 -- 486}, year = {2019}, abstract = {The propagation of a seismic rupture on a fault introduces spatial variations in the seismic wave field surrounding the fault. This directivity effect results in larger shaking amplitudes in the rupture propagation direction. Its seismic radiation pattern also causes amplitude variations between the strike-normal and strike-parallel components of horizontal ground motion. We investigated the landslide response to these effects during the 2016 Kumamoto earthquake (M-w 7.1) in central Kyushu (Japan). Although the distribution of some 1500 earthquake-triggered landslides as a function of rupture distance is consistent with the observed Arias intensity, the landslides were more concentrated to the northeast of the southwest-northeast striking rupture. We examined several landslide susceptibility factors: hillslope inclination, the median amplification factor (MAF) of ground shaking, lithology, land cover, and topographic wetness. None of these factors sufficiently explains the landslide distribution or orientation (aspect), although the landslide head scarps have an elevated hillslope inclination and MAF. We propose a new physics-based ground-motion model (GMM) that accounts for the seismic rupture effects, and we demonstrate that the low-frequency seismic radiation pattern is consistent with the overall landslide distribution. Its spatial pattern is influenced by the rupture directivity effect, whereas landslide aspect is influenced by amplitude variations between the fault-normal and fault-parallel motion at frequencies < 2 Hz. This azimuth dependence implies that comparable landslide concentrations can occur at different distances from the rupture. This quantitative link between the prevalent landslide aspect and the low-frequency seismic radiation pattern can improve coseismic landslide hazard assessment.}, language = {en} } @article{PanekKorupLenartetal.2018, author = {Panek, Tomas and Korup, Oliver and Lenart, Jan and Hradecky, Jan and Brezny, Michal}, title = {Giant landslides in the foreland of the Patagonian Ice Sheet}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {194}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2018.06.028}, pages = {39 -- 54}, year = {2018}, abstract = {Quaternary glaciations have repeatedly shaped large tracts of the Andean foreland. Its spectacular large glacial lakes, staircases of moraine ridges, and extensive outwash plains have inspired generations of scientists to reconstruct the processes, magnitude, and timing of ice build-up and decay at the mountain front. Surprisingly few of these studies noticed many dozens of giant (≥108 m3) mass-wasting deposits in the foreland. We report some of the world's largest terrestrial landslides in the eastern piedmont of the Patagonian Ice Sheet (PIS) along the traces of the former Lago Buenos Aires and Lago Puyerred{\´o}n glacier lobes and lakes. More than 283 large rotational slides and lateral spreads followed by debris slides, earthflows, rotational and translational rockslides, complex slides and few large rock avalanches detached some 164 ± 56 km3 of material from the slopes of volcanic mesetas, lake-bounding moraines, and river-gorge walls. Many of these landslide deposits intersect with well-dated moraine ridges or former glacial-lake shorelines, and offer opportunities for relative dating of slope failure. We estimate that >60\% of the landslide volume (∼96 km3) detached after the Last Glacial Maximum (LGM). Giant slope failures cross-cutting shorelines of a large Late Glacial to Early Holocene lake ("glacial lake PIS") likely occurred during successive lake-level drop between ∼11.5 and 8 ka, and some of them are the largest hitherto documented landslides in moraines. We conclude that 1) large portions of terminal moraines can fail catastrophically several thousand years after emplacement; 2) slopes formed by weak bedrock or unconsolidated glacial deposits bordering glacial lakes can release extremely large landslides; and 3) landslides still occur in the piedmont, particularly along postglacial gorges cut in response to falling lake levels.}, language = {en} } @article{MeyerSchwanghartKorupetal.2014, author = {Meyer, Nele Kristin and Schwanghart, Wolfgang and Korup, Oliver and Romstad, Bard and Etzelmuller, Bernd}, title = {Estimating the topographic predictability of debris flows}, series = {Geomorphology : an international journal on pure and applied geomorphology}, volume = {207}, journal = {Geomorphology : an international journal on pure and applied geomorphology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0169-555X}, doi = {10.1016/j.geomorph.2013.10.030}, pages = {114 -- 125}, year = {2014}, abstract = {The Norwegian traffic network is impacted by about 2000 landslides, avalanches, and debris flows each year that incur high economic losses. Despite the urgent need to mitigate future losses, efforts to locate potential debris flow source areas have been rare at the regional scale. We tackle this research gap by exploring a minimal set of possible topographic predictors of debris flow initiation that we input to a Weights-of-Evidence (WofE) model for mapping the regional susceptibility to debris flows in western Norway. We use an inventory of 429 debris flows that were recorded between 1979 and 2008, and use the terrain variables of slope, total curvature, and contributing area (flow accumulation) to compute the posterior probabilities of local debris flow occurrence. The novelty of our approach is that we quantify the uncertainties in the WofE approach arising from different predictor classification schemes and data input, while estimating model accuracy and predictive performance from independent test data. Our results show that a percentile-based classification scheme excels over a manual classification of the predictor variables because differing abundances in manually defined bins reduce the reliability of the conditional independence tests, a key, and often neglected, prerequisite for the WofE method. The conditional dependence between total curvature and flow accumulation precludes their joint use in the model. Slope gradient has the highest true positive rate (88\%), although the fraction of area classified as susceptible is very large (37\%). The predictive performance, i.e. the reduction of false positives, is improved when combined with either total curvature or flow accumulation. Bootstrapping shows that the combination of slope and flow accumulation provides more reliable predictions than the combination of slope and total curvature, and helps refining the use of slope-area plots for identifying morphometric fingerprints of debris flow source areas, an approach used outside the field of landslide susceptibility assessments.}, language = {en} } @article{WangCherstvyMetzleretal.2022, author = {Wang, Wei and Cherstvy, Andrey G. and Metzler, Ralf and Sokolov, Igor M.}, title = {Restoring ergodicity of stochastically reset anomalous-diffusion processes}, series = {Physical Review Research}, volume = {4}, journal = {Physical Review Research}, edition = {1}, publisher = {American Physical Society}, address = {College Park, Maryland, United States}, issn = {2643-1564}, doi = {10.1103/PhysRevResearch.4.013161}, pages = {013161-1 -- 013161-13}, year = {2022}, abstract = {How do different reset protocols affect ergodicity of a diffusion process in single-particle-tracking experiments? We here address the problem of resetting of an arbitrary stochastic anomalous-diffusion process (ADP) from the general mathematical points of view and assess ergodicity of such reset ADPs for an arbitrary resetting protocol. The process of stochastic resetting describes the events of the instantaneous restart of a particle's motion via randomly distributed returns to a preset initial position (or a set of those). The waiting times of such resetting events obey the Poissonian, Gamma, or more generic distributions with specified conditions regarding the existence of moments. Within these general approaches, we derive general analytical results and support them by computer simulations for the behavior of the reset mean-squared displacement (MSD), the new reset increment-MSD (iMSD), and the mean reset time-averaged MSD (TAMSD). For parental nonreset ADPs with the MSD(t)∝ tμ we find a generic behavior and a switch of the short-time growth of the reset iMSD and mean reset TAMSDs from ∝ _μ for subdiffusive to ∝ _1 for superdiffusive reset ADPs. The critical condition for a reset ADP that recovers its ergodicity is found to be more general than that for the nonequilibrium stationary state, where obviously the iMSD and the mean TAMSD are equal. The consideration of the new statistical quantifier, the iMSD—as compared to the standard MSD—restores the ergodicity of an arbitrary reset ADP in all situations when the μth moment of the waiting-time distribution of resetting events is finite. Potential applications of these new resetting results are, inter alia, in the area of biophysical and soft-matter systems.}, language = {en} } @article{GhoshCherstvyMetzler2015, author = {Ghosh, Surya K. and Cherstvy, Andrey G. and Metzler, Ralf}, title = {Non-universal tracer diffusion in crowded media of non-inert obstacles}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {17}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {3}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c4cp03599b}, pages = {1847 -- 1858}, year = {2015}, abstract = {We study the diffusion of a tracer particle, which moves in continuum space between a lattice of excluded volume, immobile non-inert obstacles. In particular, we analyse how the strength of the tracer-obstacle interactions and the volume occupancy of the crowders alter the diffusive motion of the tracer. From the details of partitioning of the tracer diffusion modes between trapping states when bound to obstacles and bulk diffusion, we examine the degree of localisation of the tracer in the lattice of crowders. We study the properties of the tracer diffusion in terms of the ensemble and time averaged mean squared displacements, the trapping time distributions, the amplitude variation of the time averaged mean squared displacements, and the non-Gaussianity parameter of the diffusing tracer. We conclude that tracer-obstacle adsorption and binding triggers a transient anomalous diffusion. From a very narrow spread of recorded individual time averaged trajectories we exclude continuous type random walk processes as the underlying physical model of the tracer diffusion in our system. For moderate tracer-crowder attraction the motion is found to be fully ergodic, while at stronger attraction strength a transient disparity between ensemble and time averaged mean squared displacements occurs. We also put our results into perspective with findings from experimental single-particle tracking and simulations of the diffusion of tagged tracers in dense crowded suspensions. Our results have implications for the diffusion, transport, and spreading of chemical components in highly crowded environments inside living cells and other structured liquids.}, language = {en} } @article{KarCherstvyMetzler2017, author = {Kar, Prathitha and Cherstvy, Andrey G. and Metzler, Ralf}, title = {Acceleration of bursty multiprotein target search kinetics on DNA by colocalisation}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {20}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {12}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c7cp06922g}, pages = {7931 -- 7946}, year = {2017}, abstract = {Proteins are capable of locating specific targets on DNA by employing a facilitated diffusion process with intermittent 1D and 3D search steps. Gene colocalisation and coregulation-i.e. the spatial proximity of two communicating genes-is one factor capable of accelerating the target search process along the DNA. We perform Monte Carlo computer simulations and demonstrate the benefits of gene colocalisation for minimising the search time in a model DNA-protein system. We use a simple diffusion model to mimic the search for targets by proteins, produced initially in bursts of multiple proteins and performing the first-passage search on the DNA chain. The behaviour of the mean first-passage times to the target is studied as a function of distance between the initial position of proteins and the DNA target position, as well as versus the concentration of proteins. We also examine the properties of bursty target search kinetics for varying physical-chemical protein-DNA binding affinity. Our findings underline the relevance of colocalisation of production and binding sites for protein search inside biological cells.}, language = {en} } @article{PalyulinChechkinKlagesetal.2016, author = {Palyulin, Vladimir V. and Chechkin, Aleksei and Klages, Rainer and Metzler, Ralf}, title = {Search reliability and search efficiency of combined Levy-Brownian motion: long relocations mingled with thorough local exploration}, series = {Journal of physics : A, Mathematical and theoretical}, volume = {49}, journal = {Journal of physics : A, Mathematical and theoretical}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {1751-8113}, doi = {10.1088/1751-8113/49/39/394002}, pages = {2189 -- 2193}, year = {2016}, abstract = {A combined dynamics consisting of Brownian motion and Levy flights is exhibited by a variety of biological systems performing search processes. Assessing the search reliability of ever locating the target and the search efficiency of doing so economically of such dynamics thus poses an important problem. Here we model this dynamics by a one-dimensional fractional Fokker-Planck equation combining unbiased Brownian motion and Levy flights. By solving this equation both analytically and numerically we show that the superposition of recurrent Brownian motion and Levy flights with stable exponent alpha < 1, by itself implying zero probability of hitting a point on a line, leads to transient motion with finite probability of hitting any point on the line. We present results for the exact dependence of the values of both the search reliability and the search efficiency on the distance between the starting and target positions as well as the choice of the scaling exponent a of the Levy flight component.}, language = {en} } @article{CherstvyVinodAghionetal.2017, author = {Cherstvy, Andrey G. and Vinod, Deepak and Aghion, Erez and Chechkin, Aleksei and Metzler, Ralf}, title = {Time averaging, ageing and delay analysis of financial time series}, series = {New journal of physics}, volume = {19}, journal = {New journal of physics}, publisher = {IOP}, address = {London}, issn = {1367-2630}, doi = {10.1088/1367-2630/aa7199}, pages = {1 -- 11}, year = {2017}, abstract = {We introduce three strategies for the analysis of financial time series based on time averaged observables. These comprise the time averaged mean squared displacement (MSD) as well as the ageing and delay time methods for varying fractions of the financial time series. We explore these concepts via statistical analysis of historic time series for several Dow Jones Industrial indices for the period from the 1960s to 2015. Remarkably, we discover a simple universal law for the delay time averaged MSD. The observed features of the financial time series dynamics agree well with our analytical results for the time averaged measurables for geometric Brownian motion, underlying the famed Black-Scholes-Merton model. The concepts we promote here are shown to be useful for financial data analysis and enable one to unveil new universal features of stock market dynamics.}, language = {en} } @misc{CherstvyVinodAghionetal.2017, author = {Cherstvy, Andrey G. and Vinod, Deepak and Aghion, Erez and Chechkin, Aleksei and Metzler, Ralf}, title = {Time averaging, ageing and delay analysis of financial time series}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400541}, pages = {11}, year = {2017}, abstract = {We introduce three strategies for the analysis of financial time series based on time averaged observables. These comprise the time averaged mean squared displacement (MSD) as well as the ageing and delay time methods for varying fractions of the financial time series. We explore these concepts via statistical analysis of historic time series for several Dow Jones Industrial indices for the period from the 1960s to 2015. Remarkably, we discover a simple universal law for the delay time averaged MSD. The observed features of the financial time series dynamics agree well with our analytical results for the time averaged measurables for geometric Brownian motion, underlying the famed Black-Scholes-Merton model. The concepts we promote here are shown to be useful for financial data analysis and enable one to unveil new universal features of stock market dynamics.}, language = {en} } @article{FanvanWestenKorupetal.2012, author = {Fan, Xuanmei and van Westen, Cees J. and Korup, Oliver and Gorum, Tolga and Xu, Qiang and Dai, Fuchu and Huang, Runqiu and Wang, Gonghui}, title = {Transient water and sediment storage of the decaying landslide dams induced by the 2008 Wenchuan earthquake, China}, series = {Geomorphology : an international journal on pure and applied geomorphology}, volume = {171}, journal = {Geomorphology : an international journal on pure and applied geomorphology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0169-555X}, doi = {10.1016/j.geomorph.2012.05.003}, pages = {58 -- 68}, year = {2012}, abstract = {Earthquake-triggered landslide dams are potentially dangerous disrupters of water and sediment flux in mountain rivers, and capable of releasing catastrophic outburst flows to downstream areas. We analyze an inventory of 828 landslide dams in the Longmen Shan mountains, China, triggered by the M-w 7.9 2008 Wenchuan earthquake. This database is unique in that it is the largest of its kind attributable to a single regional-scale triggering event: 501 of the spatially clustered landslides fully blocked rivers, while the remainder only partially obstructed or diverted channels in steep watersheds of the hanging wall of the Yingxiu-Beichuan Fault Zone. The size distributions of the earthquake-triggered landslides, landslide dams, and associated lakes (a) can be modeled by an inverse gamma distribution; (b) show that moderate-size slope failures caused the majority of blockages; and (c) allow a detailed assessment of seismically induced river-blockage effects on regional water and sediment storage. Monte Carlo simulations based on volumetric scaling relationships for soil and bedrock failures respectively indicate that 14\% (18\%) of the estimated total coseismic landslide volume of 6.4 (14.6) x 10(9) m(3) was contained in landslide dams, representing only 1.4\% of the >60,000 slope failures attributed to the earthquake. These dams have created storage capacity of similar to 0.6x 10(9) m(3) for incoming water and sediment. About 25\% of the dams containing 2\% of the total river-blocking debris volume failed one week after the earthquake; these figures had risen to 60\% (similar to 20\%), and >90\% (>90\%) within one month, and one:year, respectively, thus also emptying similar to 92\% of the total potential water and sediment storage behind these, dams within one year following the earthquake. Currently only similar to 0.08 x 10(9) m(3) remain available as natural reservoirs for storing water and sediment, while similar to 0.19 x 10(9) m(3), i.e. about a third of the total river-blocking debris volume, has been eroded by rivers. Dam volume and upstream catchment area control to first order the longevity of the barriers, and bivariate domain plots are consistent with the observation that most earthquake-triggered landslide dams were ephemeral. We conclude that the river-blocking portion of coseismic slope failures disproportionately modulates the post-seismic sediment flux in the Longmen Shan on annual to decadal timescales.}, language = {en} } @article{KluthStadionGottmannetal.2019, author = {Kluth, Oliver and Stadion, Mandy and Gottmann, Pascal and Aga-Barfknecht, Heja and J{\"a}hnert, Markus and Scherneck, Stephan and Vogel, Heike and Krus, Ulrika and Seelig, Anett and Ling, Charlotte and Gerdes, Jantje and Sch{\"u}rmann, Annette}, title = {Decreased expression of cilia genes in pancreatic islets as a risk factor for type 2 diabetes in mice and humans}, series = {Cell reports}, volume = {26}, journal = {Cell reports}, number = {11}, publisher = {Cell Press}, address = {Maryland Heights}, issn = {2211-1247}, doi = {10.1016/j.celrep.2019.02.056}, pages = {3027 -- 3036}, year = {2019}, abstract = {An insufficient adaptive beta-cell compensation is a hallmark of type 2 diabetes (T2D). Primary cilia function as versatile sensory antennae regulating various cellular processes, but their role on compensatory beta-cell replication has not been examined. Here, we identify a significant enrichment of downregulated, cilia-annotated genes in pancreatic islets of diabetes-prone NZO mice as compared with diabetes-resistant B6-ob/ob mice. Among 327 differentially expressed mouse cilia genes, 81 human orthologs are also affected in islets of diabetic donors. Islets of nondiabetic mice and humans show a substantial overlap of upregulated cilia genes that are linked to cell-cycle progression. The shRNA-mediated suppression of KIF3A, essential for ciliogenesis, impairs division of MINE beta cells as well as in dispersed primary mouse and human islet cells, as shown by decreased BrdU incorporation. These findings demonstrate the substantial role of cilia-gene regulation on islet function and T2D risk.}, language = {en} } @article{GorumKorupvanWestenetal.2014, author = {Gorum, Tolga and Korup, Oliver and van Westen, Cees J. and van der Meijde, Mark and Xu, Chong and van der Meer, Freek D.}, title = {Why so few? Landslides triggered by the 2002 Denali earthquake, Alaska}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {95}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2014.04.032}, pages = {80 -- 94}, year = {2014}, abstract = {The 2002 M-w 7.9 Denali Fault earthquake, Alaska, provides an unparalleled opportunity to investigate in quantitative detail the regional hillslope mass-wasting response to strong seismic shaking in glacierized terrain. We present the first detailed inventory of similar to 1580 coseismic slope failures, out of which some 20\% occurred above large valley glaciers, based on mapping from multi-temporal remote sensing data. We find that the Denali earthquake produced at least one order of magnitude fewer landslides in a much narrower corridor along the fault ruptures than empirical predictions for an M 8 earthquake would suggest, despite the availability of sufficiently steep and dissected mountainous topography prone to frequent slope failure. In order to explore potential controls on the reduced extent of regional coseismic landsliding we compare our data with inventories that we compiled for two recent earthquakes in periglacial and formerly glaciated terrain, i.e. at Yushu, Tibet (M-w 6.9, 2010), and Aysen Fjord, Chile (2007 M-w 6.2). Fault movement during these events was, similarly to that of the Denali earthquake, dominated by strike-slip offsets along near-vertical faults. Our comparison returns very similar coseismic landslide patterns that are consistent with the idea that fault type, geometry, and dynamic rupture process rather than widespread glacier cover were among the first-order controls on regional hillslope erosional response in these earthquakes. We conclude that estimating the amount of coseismic hillslope sediment input to the sediment cascade from earthquake magnitude alone remains highly problematic, particularly if glacierized terrain is involved. (C) 2014 Elsevier Ltd. All rights reserved.}, language = {en} } @article{KorupGoeruemHayakawa2012, author = {Korup, Oliver and G{\"o}r{\"u}m, Tolga and Hayakawa, Yuichi}, title = {Without power? - Landslide inventories in the face of climate change}, series = {Earth surface processes and landforms : the journal of the British Geomorphological Research Group}, volume = {37}, journal = {Earth surface processes and landforms : the journal of the British Geomorphological Research Group}, number = {1}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0197-9337}, doi = {10.1002/esp.2248}, pages = {92 -- 99}, year = {2012}, abstract = {Projected scenarios of climate change involve general predictions about the likely changes to the magnitude and frequency of landslides, particularly as a consequence of altered precipitation and temperature regimes. Whether such landslide response to contemporary or past climate change may be captured in differing scaling statistics of landslide size distributions and the erosion rates derived thereof remains debated. We test this notion with simple Monte Carlo and bootstrap simulations of statistical models commonly used to characterize empirical landslide size distributions. Our results show that significant changes to total volumes contained in such inventories may be masked by statistically indistinguishable scaling parameters, critically depending on, among others, the size of the largest of landslides recorded. Conversely, comparable model parameter values may obscure significant, i.e. more than twofold, changes to landslide occurrence, and thus inferred rates of hillslope denudation and sediment delivery to drainage networks. A time series of some of Earth's largest mass movements reveals clustering near and partly before the last glacial-interglacial transition and a distinct step-over from white noise to temporal clustering around this period. However, elucidating whether this is a distinct signal of first-order climate-change impact on slope stability or simply coincides with a transition from short-term statistical noise to long-term steady-state conditions remains an important research challenge.}, language = {en} } @article{GhoshCherstvyPetrovetal.2016, author = {Ghosh, Surya K. and Cherstvy, Andrey G. and Petrov, Eugene P. and Metzler, Ralf}, title = {Interactions of rod-like particles on responsive elastic sheets}, series = {Soft matter}, journal = {Soft matter}, publisher = {RSC}, address = {London}, issn = {1744-6848}, doi = {10.1039/C6SM01522K}, year = {2016}, abstract = {What are the physical laws of the mutual interactions of objects bound to cell membranes, such as various membrane proteins or elongated virus particles? To rationalise this, we here investigate by extensive computer simulations mutual interactions of rod-like particles adsorbed on the surface of responsive elastic two-dimensional sheets. Specifically, we quantify sheet deformations as a response to adhesion of such filamentous particles. We demonstrate that tip-to-tip contacts of rods are favoured for relatively soft sheets, while side-by-side contacts are preferred for stiffer elastic substrates. These attractive orientation-dependent substrate-mediated interactions between the rod-like particles on responsive sheets can drive their aggregation and self-assembly. The optimal orientation of the membrane-bound rods is established via responding to the elastic energy profiles created around the particles. We unveil the phase diagramme of attractive-repulsive rod-rod interactions in the plane of their separation and mutual orientation. Applications of our results to other systems featuring membrane-associated particles are also discussed.}, language = {en} } @article{ChechkinZaidLomholtetal.2012, author = {Chechkin, Aleksei and Zaid, Irwin M. and Lomholt, Michael A. and Sokolov, Igor M. and Metzler, Ralf}, title = {Bulk-mediated diffusion on a planar surface full solution}, series = {Physical review : E, Statistical, nonlinear and soft matter physics}, volume = {86}, journal = {Physical review : E, Statistical, nonlinear and soft matter physics}, number = {4}, publisher = {American Physical Society}, address = {College Park}, issn = {1539-3755}, doi = {10.1103/PhysRevE.86.041101}, pages = {11}, year = {2012}, abstract = {We consider the effective surface motion of a particle that intermittently unbinds from a planar surface and performs bulk excursions. Based on a random-walk approach, we derive the diffusion equations for surface and bulk diffusion including the surface-bulk coupling. From these exact dynamic equations, we analytically obtain the propagator of the effective surface motion. This approach allows us to deduce a superdiffusive, Cauchy-type behavior on the surface, together with exact cutoffs limiting the Cauchy form. Moreover, we study the long-time dynamics for the surface motion.}, language = {en} } @misc{MetzlerJeonCherstvyetal.2014, author = {Metzler, Ralf and Jeon, Jae-Hyung and Cherstvy, Andrey G. and Barkai, Eli}, title = {Anomalous diffusion models and their properties}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-74448}, pages = {24128 -- 24164}, year = {2014}, abstract = {Modern microscopic techniques following the stochastic motion of labelled tracer particles have uncovered significant deviations from the laws of Brownian motion in a variety of animate and inanimate systems. Such anomalous diffusion can have different physical origins, which can be identified from careful data analysis. In particular, single particle tracking provides the entire trajectory of the traced particle, which allows one to evaluate different observables to quantify the dynamics of the system under observation. We here provide an extensive overview over different popular anomalous diffusion models and their properties. We pay special attention to their ergodic properties, highlighting the fact that in several of these models the long time averaged mean squared displacement shows a distinct disparity to the regular, ensemble averaged mean squared displacement. In these cases, data obtained from time averages cannot be interpreted by the standard theoretical results for the ensemble averages. Here we therefore provide a comparison of the main properties of the time averaged mean squared displacement and its statistical behaviour in terms of the scatter of the amplitudes between the time averages obtained from different trajectories. We especially demonstrate how anomalous dynamics may be identified for systems, which, on first sight, appear to be Brownian. Moreover, we discuss the ergodicity breaking parameters for the different anomalous stochastic processes and showcase the physical origins for the various behaviours. This Perspective is intended as a guidebook for both experimentalists and theorists working on systems, which exhibit anomalous diffusion.}, language = {en} } @article{OzturkWendiCrisologoetal.2018, author = {Ozturk, Ugur and Wendi, Dadiyorto and Crisologo, Irene and Riemer, Adrian and Agarwal, Ankit and Vogel, Kristin and Andres Lopez-Tarazon, Jose and Korup, Oliver}, title = {Rare flash floods and debris flows in southern Germany}, series = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man}, volume = {626}, journal = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0048-9697}, doi = {10.1016/j.scitotenv.2018.01.172}, pages = {941 -- 952}, year = {2018}, abstract = {Flash floods and debris flows are iconic hazards inmountainous regions with steep relief, high rainfall intensities, rapid snowmelt events, and abundant sediments. The cuesta landscapes of southern Germany hardly come to mind when dealing with such hazards. A series of heavy rainstorms dumping up to 140mm in 2 h caused destructive flash floods and debris flows in May 2016. The most severe damage occurred in the Braunsbach municipality, which was partly buried by 42,000 m(3) of boulders, gravel, mud, and anthropogenic debris from the small catchment of Orlacher Bach (similar to 6 km(2)). We analysed this event by combining rainfall patterns, geological conditions, and geomorphic impacts to estimate an average sediment yield of 14,000 t/km(2) that mostly (similar to 95\%) came from some 50 riparian landslides and channel-bed incision of similar to 2 m. This specific sediment yield ranks among the top 20\% globally, while the intensity-duration curve of the rainstormis similarly in the upper percentile range of storms that had triggered landslides. Compared to similar-sized catchments in the greater region hit by the rainstorms, we find that the Orlacher Bach is above the 95th percentile in terms of steepness, storm-rainfall intensity, and topographic curvatures. The flash flood transported a sediment volume equal to as much as 20-40\% of the Pleistocene sediment volume stored in the Orlacher Bach fan, andmay have had several predecessors in the Holocene. River control structures from 1903 and records of a debris flow in the 1920s in a nearby catchment indicate that the local inhabitants may have been aware of the debris-flow hazards earlier. Such recurring and destructive events elude flood-hazard appraisals in humid landscapes of gentle relief, and broaden mechanistic views of how landslides and debris flows contribute to shaping small and deeply cut tributaries in the southern Germany cuesta landscape.}, language = {en} } @article{SchoenfeldtPanekWinocuretal.2020, author = {Sch{\"o}nfeldt, Elisabeth and P{\´a}nek, Tom{\´a}š and Winocur, Diego and Silhan, Karel and Korup, Oliver}, title = {Postglacial Patagonian mass movement}, series = {Geomorphology : an international journal on pure and applied geomorphology}, volume = {367}, journal = {Geomorphology : an international journal on pure and applied geomorphology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0169-555X}, doi = {10.1016/j.geomorph.2020.107316}, pages = {16}, year = {2020}, abstract = {Many of the volcanic plateau margins of the eastern, formerly glaciated, foreland of the Patagonian Andes are undermined by giant landslides (>= 10(8) m(3)). One cluster of such landslides extends along the margin of the Meseta del Lago Buenos Aires (MLBA) plateau that is formed mainly by Neogene-Quaternary basalts. The dry climate is at odds with numerous >2-km long earthflows nested within older and larger compound landslides. We present a hydrological analysis, a detailed geomorphic map, interpretations of exposed landslide interiors, and radiocarbon dating of the El Mirador landslide, which is one of the largest and morphologically most representative landslide. We find that the presence of lakes on top of the plateau, causing low infiltration rates, correlates negatively with the abundance of earthflows on compound landslides along the plateau margins. Field outcrops show that the pattern of compound landslides and earthflows is likely controlled by groundwater seepage at the contact between the basalts and underlying soft Miocene molasse. Numerous peat bogs store water and sediment and are more abundant in earthflow-affected areas than in their contributing catchment areas.
Radiocarbon dates indicate that these earthflows displaced metre-thick layers of peat in the late Holocene (<2.5 ka). We conclude that earthflows of the MLBA plateau might be promising proxies of past hydroclimatic conditions in the Patagonian foreland, if strong earthquakes or gradual crustal stress changes due to glacioisostatic rebound can be ruled out.}, language = {en} } @article{DrewesMoreirasKorup2018, author = {Drewes, Julia and Moreiras, Stella and Korup, Oliver}, title = {Permafrost activity and atmospheric warming in the Argentinian Andes}, series = {Geomorphology : an international journal on pure and applied geomorphology}, volume = {323}, journal = {Geomorphology : an international journal on pure and applied geomorphology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0169-555X}, doi = {10.1016/j.geomorph.2018.09.005}, pages = {13 -- 24}, year = {2018}, abstract = {Rock glaciers are permafrost or glacial landforms of debris and ice that deform under the influence of gravity. Recent estimates hold that, in the semiarid Chilean Andes for example, active rock glaciers store more water than glaciers. However, little is known about how many rock glaciers might decay because of global warming and how much this decay might contribute to water and sediment release. We investigated an inventory of >6500 rock glaciers in the Argentinian Andes, spanning the climatic gradient from the Desert Andes to cold-temperate Tierra del Fuego. We used active rock glaciers as a diagnostic of permafrost, assuming that the toes mark the 0 degrees C isotherm in climate scenarios for the twenty-first century and their impact on freezing conditions near the rock glacier toes. We find that, under future worst case warming, up to 95\% of rock glaciers in the southern Desert Andes and in the Central Andes will rest in areas above 0 degrees C and that this freezing level might move up more than twice as much (similar to 500 m) as during the entire Holocene (similar to 200 m). Many active rock glaciers are already well below the current freezing level and exemplify how local controls may confound regional prognoses. A Bayesian Multifactor Analysis of Variance further shows that only in the Central Andes are the toes of active rock glaciers credibly higher than those of inactive ones. Elsewhere in the Andes, active and inactive rock glaciers occupy indistinguishable elevation bands, regardless of aspect, the formation mechanism, or shape of rock glaciers. The state of rock glacier activity predicts differences in elevations of toes to 140 m at best so that regional inference of the distribution of discontinuous permafrost from rock-glacier toes cannot be more accurate than this in the Argentinian Andes. We conclude that the Central Andes-where rock glaciers are largest, cover the most area, and have a greater density than glaciers-is likely to experience the most widespread disturbance to the thermal regime of the twenty-first century. (C) 2018 Elsevier B.V. All rights reserved.}, language = {en} } @article{SchwanghartWorniHuggeletal.2016, author = {Schwanghart, Wolfgang and Worni, Raphael and Huggel, Christian and Stoffel, Markus and Korup, Oliver}, title = {Uncertainty in the Himalayan energy-water nexus}, series = {Environmental research letters : ERL}, volume = {11}, journal = {Environmental research letters : ERL}, publisher = {IOP Publ.}, address = {Bristol}, issn = {1748-9326}, doi = {10.1088/1748-9326/11/7/074005}, pages = {9}, year = {2016}, abstract = {Himalayan water resources attract a rapidly growing number of hydroelectric power projects (HPP) to satisfy Asia's soaring energy demands. Yet HPP operating or planned in steep, glacier-fed mountain rivers face hazards of glacial lake outburst floods (GLOFs) that can damage hydropower infrastructure, alter water and sediment yields, and compromise livelihoods downstream. Detailed appraisals of such GLOF hazards are limited to case studies, however, and a more comprehensive, systematic analysis remains elusive. To this end we estimate the regional exposure of 257 Himalayan HPP to GLOFs, using a flood-wave propagation model fed by Monte Carlo-derived outburst volumes of >2300 glacial lakes. We interpret the spread of thus modeled peak discharges as a predictive uncertainty that arises mainly from outburst volumes and dam-breach rates that are difficult to assess before dams fail. With 66\% of sampled HPP are on potential GLOF tracks, up to one third of these HPP could experience GLOF discharges well above local design floods, as hydropower development continues to seek higher sites closer to glacial lakes. We compute that this systematic push of HPP into headwaters effectively doubles the uncertainty about GLOF peak discharge in these locations. Peak discharges farther downstream, in contrast, are easier to predict because GLOF waves attenuate rapidly. Considering this systematic pattern of regional GLOF exposure might aid the site selection of future Himalayan HPP. Our method can augment, and help to regularly update, current hazard assessments, given that global warming is likely changing the number and size of Himalayan meltwater lakes.}, language = {en} } @article{StruckAndermannHoviusetal.2015, author = {Struck, Martin and Andermann, Christoff and Hovius, Niels and Korup, Oliver and Turowski, Jens M. and Bista, Raj and Pandit, Hari P. and Dahal, Ranjan K.}, title = {Monsoonal hillslope processes determine grain size-specific suspended sediment fluxes in a trans-Himalayan river}, series = {Geophysical research letters}, volume = {42}, journal = {Geophysical research letters}, number = {7}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0094-8276}, doi = {10.1002/2015GL063360}, pages = {2302 -- 2308}, year = {2015}, abstract = {Sediments in rivers record the dynamics of erosion processes. While bulk sediment fluxes are easily and routinely obtained, sediment caliber remains underexplored when inferring erosion mechanisms. Yet sediment grain size distributions may be the key to discriminating their origin. We have studied grain size-specific suspended sediment fluxes in the Kali Gandaki, a major trans-Himalayan river. Two strategically located gauging stations enable tracing of sediment caliber on either side of the Himalayan orographic barrier. The data show that fine sediment input into the northern headwaters is persistent, while coarse sediment comes from the High Himalayas during the summer monsoon. A temporally matching landslide inventory similarly indicates the prominence of monsoon-driven hillslope mass wasting. Thus, mechanisms of sediment supply can leave strong traces in the fluvial caliber, which could project well beyond the mountain front and add to the variability of the sedimentary record of orogen erosion.}, language = {en} } @article{SafdariCherstvyChechkinetal.2015, author = {Safdari, Hadiseh and Cherstvy, Andrey G. and Chechkin, Aleksei and Thiel, Felix and Sokolov, Igor M. and Metzler, Ralf}, title = {Quantifying the non-ergodicity of scaled Brownian motion}, series = {Journal of physics : A, Mathematical and theoretical}, volume = {48}, journal = {Journal of physics : A, Mathematical and theoretical}, number = {37}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {1751-8113}, doi = {10.1088/1751-8113/48/37/375002}, pages = {18}, year = {2015}, abstract = {We examine the non-ergodic properties of scaled Brownian motion (SBM), a non-stationary stochastic process with a time dependent diffusivity of the form D(t) similar or equal to t(alpha-1). We compute the ergodicity breaking parameter EB in the entire range of scaling exponents a, both analytically and via extensive computer simulations of the stochastic Langevin equation. We demonstrate that in the limit of long trajectory lengths T and short lag times Delta the EB parameter as function of the scaling exponent a has no divergence at alpha - 1/2 and present the asymptotes for EB in different limits. We generalize the analytical and simulations results for the time averaged and ergodic properties of SBM in the presence of ageing, that is, when the observation of the system starts only a finite time span after its initiation. The approach developed here for the calculation of the higher time averaged moments of the particle displacement can be applied to derive the ergodic properties of other stochastic processes such as fractional Brownian motion.}, language = {en} } @misc{SchoenfeldtPanekWinocuretal.2020, author = {Schoenfeldt, Elisabeth and Panek, Tomas and Winocur, Diego and Silhan, Karel and Korup, Oliver}, title = {Corrigendum to: postglacial Patagonian mass movement}, series = {Geomorphology : an international journal on pure and applied geomorphology}, volume = {373}, journal = {Geomorphology : an international journal on pure and applied geomorphology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0169-555X}, doi = {10.1016/j.geomorph.2020.107471}, pages = {1}, year = {2020}, language = {en} } @article{StieglerPahlGuillenetal.2023, author = {Stiegler, Jonas and Pahl, Janice and Guillen, Rafael Arce and Ullmann, Wiebke and Blaum, Niels}, title = {The heat is on}, series = {Frontiers in Ecology and Evolution}, volume = {11}, journal = {Frontiers in Ecology and Evolution}, publisher = {Frontiers Media}, address = {Lausanne}, issn = {2296-701X}, doi = {10.3389/fevo.2023.1193861}, pages = {10}, year = {2023}, abstract = {Climate conditions severely impact the activity and, consequently, the fitness of wildlife species across the globe. Wildlife can respond to new climatic conditions, but the pace of human-induced change limits opportunities for adaptation or migration. Thus, how these changes affect behavior, movement patterns, and activity levels remains unclear. In this study, we investigate how extreme weather conditions affect the activity of European hares (Lepus europaeus) during their peak reproduction period. When hares must additionally invest energy in mating, prevailing against competitors, or lactating, we investigated their sensitivities to rising temperatures, wind speed, and humidity. To quantify their activity, we used the overall dynamic body acceleration (ODBA) calculated from tri-axial acceleration measurements of 33 GPS-collared hares. Our analysis revealed that temperature, humidity, and wind speed are important in explaining changes in activity, with a strong response for high temperatures above 25 \& DEG;C and the highest change in activity during temperature extremes of over 35 \& DEG;C during their inactive period. Further, we found a non-linear relationship between temperature and activity and an interaction of activity changes between day and night. Activity increased at higher temperatures during the inactive period (day) and decreased during the active period (night). This decrease was strongest during hot tropical nights. At a stage of life when mammals such as hares must substantially invest in reproduction, the sensitivity of females to extreme temperatures was particularly pronounced. Similarly, both sexes increased their activity at high humidity levels during the day and low wind speeds, irrespective of the time of day, while the effect of humidity was stronger for males. Our findings highlight the importance of understanding the complex relationships between extreme weather conditions and mammal behavior, critical for conservation and management. With ongoing climate change, extreme weather events such as heat waves and heavy rainfall are predicted to occur more often and last longer. These events will directly impact the fitness of hares and other wildlife species and hence the population dynamics of already declining populations across Europe.}, language = {en} } @article{HenkelFredeSchanzeetal.2012, author = {Henkel, Janin and Frede, Katja and Schanze, Nancy and Vogel, Heike and Sch{\"u}rmann, Annette and Spruß, Astrid and Bergheim, Ina and P{\"u}schel, Gerhard Paul}, title = {Stimulation of fat accumulation in hepatocytes by PGE(2)-dependent repression of hepatic lipolysis, beta-oxidation and VLDL-synthesis}, series = {Laboratory investigation : the basic and translational pathology research journal ; an official journal of the United States and Canadian Academy of Pathology}, volume = {92}, journal = {Laboratory investigation : the basic and translational pathology research journal ; an official journal of the United States and Canadian Academy of Pathology}, number = {11}, publisher = {Nature Publ. Group}, address = {New York}, issn = {0023-6837}, doi = {10.1038/labinvest.2012.128}, pages = {1597 -- 1606}, year = {2012}, abstract = {Hepatic steatosis is recognized as hepatic presentation of the metabolic syndrome. Hyperinsulinaemia, which shifts fatty acid oxidation to de novo lipogenesis and lipid storage in the liver, appears to be a principal elicitor particularly in the early stages of disease development. The impact of PGE(2), which has previously been shown to attenuate insulin signaling and hence might reduce insulin-dependent lipid accumulation, on insulin-induced steatosis of hepatocytes was studied. The PGE(2)-generating capacity was enhanced in various obese mouse models by the induction of cyclooxygenase 2 and microsomal prostaglandin E-synthases (mPGES1, mPGES2). PGE(2) attenuated the insulin-dependent induction of SREBP-1c and its target genes glucokinase and fatty acid synthase. Nevertheless, PGE(2) enhanced incorporation of glucose into hepatic triglycerides synergistically with insulin. This was most likely due to a combination of a PGE(2)-dependent repression of (1) the key lipolytic enzyme adipose triglyceride lipase, (2) carnitine-palmitoyltransferase 1, a key regulator of mitochondrial beta-oxidation, and (3) microsomal transfer protein, as well as (4) apolipoprotein B, key components of the VLDL synthesis. Repression of PGC1 alpha, a common upstream regulator of these genes, was identified as a possible cause. In support of this hypothesis, overexpression of PGC1 alpha completely blunted the PGE(2)-dependent fat accumulation. PGE(2) enhanced lipid accumulation synergistically with insulin, despite attenuating insulin signaling and might thus contribute to the development of hepatic steatosis. Induction of enzymes involved in PGE(2) synthesis in in vivo models of obesity imply a potential role of prostanoids in the development of NAFLD and NASH. Laboratory Investigation (2012) 92, 1597-1606; doi:10.1038/labinvest.2012.128; published online 10 September 2012}, language = {en} } @article{ParrySchlaegelTiedemannetal.2022, author = {Parry, Victor and Schl{\"a}gel, Ulrike and Tiedemann, Ralph and Weithoff, Guntram}, title = {Behavioural responses of defended and undefended prey to their predator}, series = {Biology : open access journal}, volume = {11}, journal = {Biology : open access journal}, number = {8}, publisher = {MDPI}, address = {Basel}, issn = {2079-7737}, doi = {10.3390/biology11081217}, pages = {14}, year = {2022}, abstract = {Many animals that have to cope with predation have evolved mechanisms to reduce their predation risk. One of these mechanisms is change in morphology, for example, the development of spines. These spines are induced, when mothers receive chemical signals of a predator (kairomones) and their daughters are then equipped with defensive spines. We studied the behaviour of a prey and its predator when the prey is either defended or undefended. We used common aquatic micro-invertebrates, the rotifers Brachionus calyciflorus (prey) and Asplanchna brightwellii (predator) as experimental animals. We found that undefended prey increased its swimming speed in the presence of the predator. The striking result was that the defended prey did not respond to the predator's presence. This suggests that defended prey has a different response behaviour to a predator than undefended conspecifics. Our study provides further insights into complex zooplankton predator-prey interactions. Predation is a strong species interaction causing severe harm or death to prey. Thus, prey species have evolved various defence strategies to minimize predation risk, which may be immediate (e.g., a change in behaviour) or transgenerational (morphological defence structures). We studied the behaviour of two strains of a rotiferan prey (Brachionus calyciflorus) that differ in their ability to develop morphological defences in response to their predator Asplanchna brightwellii. Using video analysis, we tested: (a) if two strains differ in their response to predator presence and predator cues when both are undefended; (b) whether defended individuals respond to live predators or their cues; and (c) if the morphological defence (large spines) per se has an effect on the swimming behaviour. We found a clear increase in swimming speed for both undefended strains in predator presence. However, the defended specimens responded neither to the predator presence nor to their cues, showing that they behave indifferently to their predator when they are defended. We did not detect an effect of the spines on the swimming behaviour. Our study demonstrates a complex plastic behaviour of the prey, not only in the presence of their predator, but also with respect to their defence status.}, language = {en} } @article{CrawfordJeltschMayetal.2018, author = {Crawford, Michael and Jeltsch, Florian and May, Felix and Grimm, Volker and Schl{\"a}gel, Ulrike}, title = {Intraspecific trait variation increases species diversity in a trait-based grassland model}, series = {Oikos}, volume = {128}, journal = {Oikos}, number = {3}, publisher = {Wiley}, address = {Hoboken}, issn = {0030-1299}, doi = {10.1111/oik.05567}, pages = {441 -- 455}, year = {2018}, abstract = {Intraspecific trait variation (ITV) is thought to play a significant role in community assembly, but the magnitude and direction of its influence are not well understood. Although it may be critical to better explain population persistence, species interactions, and therefore biodiversity patterns, manipulating ITV in experiments is challenging. We therefore incorporated ITV into a trait- and individual-based model of grassland community assembly by adding variation to the plants' functional traits, which then drive life-history tradeoffs. Varying the amount of ITV in the simulation, we examine its influence on pairwise-coexistence and then on the species diversity in communities of different initial sizes. We find that ITV increases the ability of the weakest species to invade most, but that this effect does not scale to the community level, where the primary effect of ITV is to increase the persistence and abundance of the competitively-average species. Diversity of the initial community is also of critical importance in determining ITV's efficacy; above a threshold of interspecific diversity, ITV does not increase diversity further. For communities below this threshold, ITV mainly helps to increase diversity in those communities that would otherwise be low-diversity. These findings suggest that ITV actively maintains diversity by helping the species on the margins of persistence, but mostly in habitats of relatively low alpha and beta diversity.}, language = {en} } @article{DelleSideNassisiPennettaetal.2017, author = {Delle Side, Domenico and Nassisi, Vincenzo and Pennetta, Cecilia and Alifano, Pietro and Di Salvo, Marco and Tala, Adelfia and Chechkin, Aleksei and Seno, Flavio and Trovato, Antonio}, title = {Bacterial bioluminescence onset and quenching: a dynamical model for a quorum sensing-mediated property}, series = {Royal Society Open Science}, volume = {4}, journal = {Royal Society Open Science}, publisher = {Royal Society}, address = {London}, issn = {2054-5703}, doi = {10.1098/rsos.171586}, pages = {12}, year = {2017}, abstract = {We present an effective dynamical model for the onset of bacterial bioluminescence, one of the most studied quorum sensing-mediated traits. Our model is built upon simple equations that describe the growth of the bacterial colony, the production and accumulation of autoinducer signal molecules, their sensing within bacterial cells, and the ensuing quorum activation mechanism that triggers bioluminescent emission. The model is directly tested to quantitatively reproduce the experimental distributions of photon emission times, previously measured for bacterial colonies of Vibrio jasicida, a luminescent bacterium belonging to the Harveyi clade, growing in a highly drying environment. A distinctive and novel feature of the proposed model is bioluminescence 'quenching' after a given time elapsed from activation. Using an advanced fitting procedure based on the simulated annealing algorithm, we are able to infer from the experimental observations the biochemical parameters used in the model. Such parameters are in good agreement with the literature data. As a further result, we find that, at least in our experimental conditions, light emission in bioluminescent bacteria appears to originate from a subtle balance between colony growth and quorum activation due to autoinducers diffusion, with the two phenomena occurring on the same time scale. This finding is consistent with a negative feedback mechanism previously reported for Vibrio harveyi.}, language = {en} } @article{ParrySchlaegelTiedemannetal.2022, author = {Parry, Victor and Schl{\"a}gel, Ulrike and Tiedemann, Ralph and Weithoff, Guntram}, title = {Behavioural Responses of Defended and Undefended Prey to Their Predator}, series = {Biology}, volume = {11}, journal = {Biology}, number = {8}, publisher = {MDPI}, address = {Basel, Schweiz}, issn = {2079-7737}, doi = {10.3390/biology11081217}, pages = {14}, year = {2022}, abstract = {Predation is a strong species interaction causing severe harm or death to prey. Thus, prey species have evolved various defence strategies to minimize predation risk, which may be immediate (e.g., a change in behaviour) or transgenerational (morphological defence structures). We studied the behaviour of two strains of a rotiferan prey (Brachionus calyciflorus) that differ in their ability to develop morphological defences in response to their predator Asplanchna brightwellii. Using video analysis, we tested: (a) if two strains differ in their response to predator presence and predator cues when both are undefended; (b) whether defended individuals respond to live predators or their cues; and (c) if the morphological defence (large spines) per se has an effect on the swimming behaviour. We found a clear increase in swimming speed for both undefended strains in predator presence. However, the defended specimens responded neither to the predator presence nor to their cues, showing that they behave indifferently to their predator when they are defended. We did not detect an effect of the spines on the swimming behaviour. Our study demonstrates a complex plastic behaviour of the prey, not only in the presence of their predator, but also with respect to their defence status.}, language = {en} } @article{StolleBernhardtSchwanghartetal.2017, author = {Stolle, Amelie and Bernhardt, Anne and Schwanghart, Wolfgang and Hoelzmann, Philipp and Adhikari, Basanta R. and Fort, Monique and Korup, Oliver}, title = {Catastrophic valley fills record large Himalayan earthquakes, Pokhara, Nepal}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {177}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2017.10.015}, pages = {88 -- 103}, year = {2017}, language = {en} } @misc{WangCherstvyMetzleretal.2022, author = {Wang, Wei and Cherstvy, Andrey G. and Metzler, Ralf and Sokolov, Igor M.}, title = {Restoring ergodicity of stochastically reset anomalous-diffusion processes}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1866-8372}, doi = {10.25932/publishup-56037}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-560377}, pages = {013161-1 -- 013161-13}, year = {2022}, abstract = {How do different reset protocols affect ergodicity of a diffusion process in single-particle-tracking experiments? We here address the problem of resetting of an arbitrary stochastic anomalous-diffusion process (ADP) from the general mathematical points of view and assess ergodicity of such reset ADPs for an arbitrary resetting protocol. The process of stochastic resetting describes the events of the instantaneous restart of a particle's motion via randomly distributed returns to a preset initial position (or a set of those). The waiting times of such resetting events obey the Poissonian, Gamma, or more generic distributions with specified conditions regarding the existence of moments. Within these general approaches, we derive general analytical results and support them by computer simulations for the behavior of the reset mean-squared displacement (MSD), the new reset increment-MSD (iMSD), and the mean reset time-averaged MSD (TAMSD). For parental nonreset ADPs with the MSD(t)∝ tμ we find a generic behavior and a switch of the short-time growth of the reset iMSD and mean reset TAMSDs from ∝ _μ for subdiffusive to ∝ _1 for superdiffusive reset ADPs. The critical condition for a reset ADP that recovers its ergodicity is found to be more general than that for the nonequilibrium stationary state, where obviously the iMSD and the mean TAMSD are equal. The consideration of the new statistical quantifier, the iMSD—as compared to the standard MSD—restores the ergodicity of an arbitrary reset ADP in all situations when the μth moment of the waiting-time distribution of resetting events is finite. Potential applications of these new resetting results are, inter alia, in the area of biophysical and soft-matter systems.}, language = {en} } @article{PottsSchlaegel2020, author = {Potts, Jonathan R. and Schl{\"a}gel, Ulrike}, title = {Parametrizing diffusion-taxis equations from animal movement trajectories using step selection analysis}, series = {Methods in ecology and evolution : an official journal of the British Ecological Society}, volume = {11}, journal = {Methods in ecology and evolution : an official journal of the British Ecological Society}, number = {9}, publisher = {Wiley}, address = {Hoboken}, issn = {2041-210X}, doi = {10.1111/2041-210X.13406}, pages = {1092 -- 1105}, year = {2020}, abstract = {Mathematical analysis of partial differential equations (PDEs) has led to many insights regarding the effect of organism movements on spatial population dynamics. However, their use has mainly been confined to the community of mathematical biologists, with less attention from statistical and empirical ecologists. We conjecture that this is principally due to the inherent difficulties in fitting PDEs to data. To help remedy this situation, in the context of movement ecology, we show how the popular technique of step selection analysis (SSA) can be used to parametrize a class of PDEs, calleddiffusion-taxismodels, from an animal's trajectory. We examine the accuracy of our technique on simulated data, then demonstrate the utility of diffusion-taxis models in two ways. First, for non-interacting animals, we derive the steady-state utilization distribution in a closed analytic form. Second, we give a recipe for deriving spatial pattern formation properties that emerge from interacting animals: specifically, do those interactions cause heterogeneous spatial distributions to emerge and if so, do these distributions oscillate at short times or emerge without oscillations? The second question is applied to data on concurrently tracked bank volesMyodes glareolus. Our results show that SSA can accurately parametrize diffusion-taxis equations from location data, providing the frequency of the data is not too low. We show that the steady-state distribution of our diffusion-taxis model, where it is derived, has an identical functional form to the utilization distribution given by resource selection analysis (RSA), thus formally linking (fine scale) SSA with (broad scale) RSA. For the bank vole data, we show how our SSA-PDE approach can give predictions regarding the spatial aggregation and segregation of different individuals, which are difficult to predict purely by examining results of SSA. Our methods provide a user-friendly way into the world of PDEs, via a well-used statistical technique, which should lead to tighter links between the findings of mathematical ecology and observations from empirical ecology. By providing a non-speculative link between observed movement behaviours and space use patterns on larger spatio-temporal scales, our findings will also aid integration of movement ecology into understanding spatial species distributions.}, language = {en} } @article{KalliesRappFydrichetal.2018, author = {Kallies, Gunnar and Rapp, Michael A. and Fydrich, Thomas and Fehm, Lydia and Tschorn, Mira and Teran, Christina and Schwefel, Melanie and Pietrek, Anou F. and Henze, Romy and Hellweg, Rainer and Str{\"o}hle, Andreas and Heinzel, Stephan and Heissel, Andreas}, title = {Serum brain-derived neurotrophic factor (BDNF) at rest and after acute aerobic exercise in major depressive disorder}, series = {Psychoneuroendocrinology}, volume = {102}, journal = {Psychoneuroendocrinology}, publisher = {Elsevier}, address = {Oxford}, issn = {0306-4530}, doi = {10.1016/j.psyneuen.2018.12.015}, pages = {212 -- 215}, year = {2018}, abstract = {Physiological mechanisms of an anti-depressive effect of physical exercise in major depressive disorder (MDD) seem to involve alterations in brain-derived neurotrophic factor (BDNF) level. However, previous studies which investigated this effect in a single bout of exercise, did not control for confounding peripheral factors that contribute to BDNF-alterations. Therefore, the underlying cause of exercise-induced BDNF-changes remains unclear. The current study aims to investigate serum BDNF (sBDNF)-changes due to a single-bout of graded aerobic exercise in a group of 30 outpatients with MDD, suggesting a more precise analysis method by taking plasma volume shift and number of platelets into account. Results show that exercise-induced increases in sBDNF remain significant (p<.001) when adjusting for plasma volume shift and controlling for number of platelets. The interaction of sBDNF change and number of platelets was also significant (p=.001) indicating larger sBDNF-increase in participants with smaller number of platelets. Thus, findings of this study suggest an involvement of peripheral as well as additional possibly brain-derived mechanisms explaining exercise-related BDNF release in MDD. For future studies in the field of exercise-related BDNF research, the importance of controlling for peripheral parameters is emphasized.}, language = {en} } @article{FerTietjenJeltschetal.2017, author = {Fer, Istem and Tietjen, Britta and Jeltsch, Florian and Trauth, Martin H.}, title = {Modelling vegetation change during Late Cenozoic uplift of the East African plateaus}, series = {Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences}, volume = {467}, journal = {Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0031-0182}, doi = {10.1016/j.palaeo.2016.04.007}, pages = {120 -- 130}, year = {2017}, abstract = {The present-day vegetation in the tropics is mainly characterized by forests worldwide except in tropical East Africa, where forests only occur as patches at the coast and in the uplands. These forest patches result from the peculiar aridity that is linked to the uplift of the region during the Late Cenozoic. The Late Cenozoic vegetation history of East Africa is of particular interest as it has set the scene for the contemporary events in mammal and hominin evolution. In this study, we investigate the conditions under which these forest patches could have been connected, and a previous continuous forest belt could have extended and fragmented. We apply a dynamic vegetation model with a set of climatic scenarios in which we systematically alter the present-day environmental conditions such that they would be more favourable for a continuous forest belt in tropical East Africa. We consider varying environmental factors, namely temperature, precipitation and atmospheric CO2 concentrations. Our results show that all of these variables play a significant role in supporting the forest biomes and a continuous forest belt could have occurred under certain combinations of these settings. With our current knowledge of the palaeoenvironmental history of East Africa, it is likely that the region hosted these conditions during the Late Cenozoic. Recent improvements on environmental hypotheses of hominin evolution highlight the role of periods of short and extreme climate variability during the Late Cenozoic specific to East Africa in driving evolution. Our results elucidate how the forest biomes of East Africa can appear and disappear under fluctuating environmental conditions and demonstrate how this climate variability might be recognized on the biosphere level.}, language = {en} } @article{CaetanoCarvalhoMetzleretal.2020, author = {Caetano, Daniel L. Z. and Carvalho, Sidney Jurado de and Metzler, Ralf and Cherstvy, Andrey G.}, title = {Critical adsorption of multiple polyelectrolytes onto a nanosphere}, series = {Interface : journal of the Royal Society}, volume = {17}, journal = {Interface : journal of the Royal Society}, number = {167}, publisher = {Royal Society}, address = {London}, issn = {1742-5689}, doi = {10.1098/rsif.2020.0199}, pages = {10}, year = {2020}, abstract = {Employing extensive Monte Carlo computer simulations, we investigate in detail the properties of multichain adsorption of charged flexible polyelectrolytes (PEs) onto oppositely charged spherical nanoparticles (SNPs). We quantify the conditions of critical adsorption-the phase-separation curve between the adsorbed and desorbed states of the PEs-as a function of the SNP surface-charge density and the concentration of added salt. We study the degree of fluctuations of the PE-SNP electrostatic binding energy, which we use to quantify the emergence of the phase subtransitions, including a series of partially adsorbed PE configurations. We demonstrate how the phase-separation adsorption-desorption boundary shifts and splits into multiple subtransitions at low-salt conditions, thereby generalizing and extending the results for critical adsorption of a single PE onto the SNP. The current findings are relevant for finite concentrations of PEs around the attracting SNP, such as the conditions for PE adsorption onto globular proteins carrying opposite electric charges.}, language = {en} } @article{BodrovaChechkinSokolov2019, author = {Bodrova, Anna S. and Chechkin, Aleksei and Sokolov, Igor M.}, title = {Nonrenewal resetting of scaled Brownian motion}, series = {Physical review : E, Statistical, nonlinear and soft matter physics}, volume = {100}, journal = {Physical review : E, Statistical, nonlinear and soft matter physics}, number = {1}, publisher = {American Physical Society}, address = {College Park}, issn = {2470-0045}, doi = {10.1103/PhysRevE.100.012119}, pages = {10}, year = {2019}, abstract = {We investigate an intermittent stochastic process in which diffusive motion with a time-dependent diffusion coefficient, D(t)∼tα-1, α>0 (scaled Brownian motion), is stochastically reset to its initial position and starts anew. The resetting follows a renewal process with either an exponential or a power-law distribution of the waiting times between successive renewals. The resetting events, however, do not affect the time dependence of the diffusion coefficient, so that the whole process appears to be a nonrenewal one. We discuss the mean squared displacement of a particle and the probability density function of its positions in this process. We show that scaled Brownian motion with resetting demonstrates rich behavior whose properties essentially depend on the interplay of the parameters of the resetting process and the particle's displacement infree motion. The motion of particles can remain almost unaffected by resetting but can also get slowed down or even be completely suppressed. Especially interesting are the nonstationary situations in which the mean squared displacement stagnates but the distribution of positions does not tend to any steady state. This behavior is compared to the situation [discussed in the companion paper; A. S. Bodrova et al., Phys. Rev. E 100, 012120 (2019)] in which the memory of the value of the diffusion coefficient at a resetting time is erased, so that the whole process is a fully renewal one. We show that the properties of the probability densities in such processes (erasing or retaining the memory on the diffusion coefficient) are vastly different.}, language = {en} } @misc{ShinCherstvyMetzler2014, author = {Shin, Jaeoh and Cherstvy, Andrey G. and Metzler, Ralf}, title = {Kinetics of polymer looping with macromolecular crowding: effects of volume fraction and crowder size}, publisher = {The Royal Society of Chemistry}, address = {Cambridge}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-76961}, pages = {472 -- 488}, year = {2014}, abstract = {The looping of polymers such as DNA is a fundamental process in the molecular biology of living cells, whose interior is characterised by a high degree of molecular crowding. We here investigate in detail the looping dynamics of flexible polymer chains in the presence of different degrees of crowding. From the analysis of the looping-unlooping rates and the looping probabilities of the chain ends we show that the presence of small crowders typically slows down the chain dynamics but larger crowders may in fact facilitate the looping. We rationalise these non-trivial and often counterintuitive effects of the crowder size on the looping kinetics in terms of an effective solution viscosity and standard excluded volume. It is shown that for small crowders the effect of an increased viscosity dominates, while for big crowders we argue that confinement effects (caging) prevail. The tradeoff between both trends can thus result in the impediment or facilitation of polymer looping, depending on the crowder size. We also examine how the crowding volume fraction, chain length, and the attraction strength of the contact groups of the polymer chain affect the looping kinetics and hairpin formation dynamics. Our results are relevant for DNA looping in the absence and presence of protein mediation, DNA hairpin formation, RNA folding, and the folding of polypeptide chains under biologically relevant high-crowding conditions.}, language = {en} } @misc{HauffeRathAgyapongetal.2022, author = {Hauffe, Robert and Rath, Michaela and Agyapong, Wilson and Jonas, Wenke and Vogel, Heike and Schulz, Tim Julius and Schwarz, Maria and Kipp, Anna Patricia and Bl{\"u}her, Matthias and Kleinridders, Andr{\´e}}, title = {Obesity Hinders the Protective Effect of Selenite Supplementation on Insulin Signaling}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1866-8372}, doi = {10.25932/publishup-56170}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-561709}, pages = {1 -- 16}, year = {2022}, abstract = {The intake of high-fat diets (HFDs) containing large amounts of saturated long-chain fatty acids leads to obesity, oxidative stress, inflammation, and insulin resistance. The trace element selenium, as a crucial part of antioxidative selenoproteins, can protect against the development of diet-induced insulin resistance in white adipose tissue (WAT) by increasing glutathione peroxidase 3 (GPx3) and insulin receptor (IR) expression. Whether selenite (Se) can attenuate insulin resistance in established lipotoxic and obese conditions is unclear. We confirm that GPX3 mRNA expression in adipose tissue correlates with BMI in humans. Cultivating 3T3-L1 pre-adipocytes in palmitate-containing medium followed by Se treatment attenuates insulin resistance with enhanced GPx3 and IR expression and adipocyte differentiation. However, feeding obese mice a selenium-enriched high-fat diet (SRHFD) only resulted in a modest increase in overall selenoprotein gene expression in WAT in mice with unaltered body weight development, glucose tolerance, and insulin resistance. While Se supplementation improved adipocyte morphology, it did not alter WAT insulin sensitivity. However, mice fed a SRHFD exhibited increased insulin content in the pancreas. Overall, while selenite protects against palmitate-induced insulin resistance in vitro, obesity impedes the effect of selenite on insulin action and adipose tissue metabolism in vivo.}, language = {en} } @article{WangMetzlerCherstvy2022, author = {Wang, Wei and Metzler, Ralf and Cherstvy, Andrey G.}, title = {Anomalous diffusion, aging, and nonergodicity of scaled Brownian motion with fractional Gaussian noise: overview of related experimental observations and models}, series = {Physical chemistry, chemical physics : PCCP ; a journal of European chemical societies}, volume = {24}, journal = {Physical chemistry, chemical physics : PCCP ; a journal of European chemical societies}, number = {31}, publisher = {RSC Publ.}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/d2cp01741e}, pages = {18482 -- 18504}, year = {2022}, abstract = {How does a systematic time-dependence of the diffusion coefficient D(t) affect the ergodic and statistical characteristics of fractional Brownian motion (FBM)? Here, we answer this question via studying the characteristics of a set of standard statistical quantifiers relevant to single-particle-tracking (SPT) experiments. We examine, for instance, how the behavior of the ensemble- and time-averaged mean-squared displacements-denoted as the standard MSD < x(2)(Delta)> and TAMSD <<(delta(2)(Delta))over bar>> quantifiers-of FBM featuring < x(2) (Delta >> = <<(delta(2)(Delta >)over bar>> proportional to Delta(2H) (where H is the Hurst exponent and Delta is the [lag] time) changes in the presence of a power-law deterministically varying diffusivity D-proportional to(t) proportional to t(alpha-1) -germane to the process of scaled Brownian motion (SBM)-determining the strength of fractional Gaussian noise. The resulting compound "scaled-fractional" Brownian motion or FBM-SBM is found to be nonergodic, with < x(2)(Delta >> proportional to Delta(alpha+)(2H)(-1) and <(delta 2(Delta >) over bar > proportional to Delta(2H). We also detect a stalling behavior of the MSDs for very subdiffusive SBM and FBM, when alpha + 2H - 1 < 0. The distribution of particle displacements for FBM-SBM remains Gaussian, as that for the parent processes of FBM and SBM, in the entire region of scaling exponents (0 < alpha < 2 and 0 < H < 1). The FBM-SBM process is aging in a manner similar to SBM. The velocity autocorrelation function (ACF) of particle increments of FBM-SBM exhibits a dip when the parent FBM process is subdiffusive. Both for sub- and superdiffusive FBM contributions to the FBM-SBM process, the SBM exponent affects the long-time decay exponent of the ACF. Applications of the FBM-SBM-amalgamated process to the analysis of SPT data are discussed. A comparative tabulated overview of recent experimental (mainly SPT) and computational datasets amenable for interpretation in terms of FBM-, SBM-, and FBM-SBM-like models of diffusion culminates the presentation. The statistical aspects of the dynamics of a wide range of biological systems is compared in the table, from nanosized beads in living cells, to chromosomal loci, to water diffusion in the brain, and, finally, to patterns of animal movements.}, language = {en} } @article{MohrKorupUlloaetal.2017, author = {Mohr, Christian Heinrich and Korup, Oliver and Ulloa, Hector and Iroume, Andres}, title = {Pyroclastic Eruption Boosts Organic Carbon Fluxes Into Patagonian Fjords}, series = {Global biogeochemical cycles}, volume = {31}, journal = {Global biogeochemical cycles}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0886-6236}, doi = {10.1002/2017GB005647}, pages = {1626 -- 1638}, year = {2017}, abstract = {Fjords and old-growth forests store large amounts of organic carbon. Yet the role of episodic disturbances, particularly volcanic eruptions, in mobilizing organic carbon in fjord landscapes covered by temperate rainforests remains poorly quantified. To this end, we estimated how much wood and soils were flushed to nearby fjords following the 2008 eruption of Chaiten volcano in south-central Chile, where pyroclastic sediments covered >12km(2) of pristine temperate rainforest. Field-based surveys of forest biomass, soil organic content, and dead wood transport reveal that the reworking of pyroclastic sediments delivered similar to 66,500+14,600/-14,500tC of large wood to two rivers entering the nearby Patagonian fjords in less than a decade. A similar volume of wood remains in dead tree stands and buried beneath pyroclastic deposits (similar to 79,900+21,100/-16,900tC) or stored in active river channels (5,900-10,600tC). We estimate that bank erosion mobilized similar to 132,300(+21,700)/(-30,600)tC of floodplain forest soil. Eroded and reworked forest soils have been accreting on coastal river deltas at >5mmyr(-1) since the eruption. While much of the large wood is transported out of the fjord by long-shore drift, the finer fraction from eroded forest soils is likely to be buried in the fjords. We conclude that the organic carbon fluxes boosted by rivers adjusting to high pyroclastic sediment loads may remain elevated for up to a decade and that Patagonian temperate rainforests disturbed by excessive loads of pyroclastic debris can be episodic short-lived carbon sources. Plain Language Summary Fjords and old-growth forests are important sinks of organic carbon. However, the role of volcanic eruptions in flushing organic carbon in fjord landscapes remains unexplored. Here we estimated how much forest vegetation and soils were lost to fjords following the 2008 eruption ofunknownChaiten volcano in south-central Chile. Pyroclastic sediments obliterated near-pristine temperateunknownrainforest, and the subsequent reworking of these sediments delivered in less than a decade similar to 66,000 tC of large wood to the mountain rivers, draining into the nearby Patagonian fjords. A similar volume of wood remains in dead tree stands and buried beneath pyroclastic deposits or stored in active riverunknownchannels. We estimate that similar to 130,000 tC of organic carbon-rich soil was lost to erosion, thus adding to the carbon loads. While much of the wood enters the long-shore drift in the fjord heads, the finerunknownfraction from eroded forest soils is likely to be buried in the fjords at rates that exceed regional estimates by an order of magnitude. We anticipate that these eruption-driven fluxes will remain elevated forunknownthe coming years and that Patagonian temperate rainforests episodically switch from carbon sinks to hitherto undocumented carbon sources if disturbed by explosive volcanic eruptions.}, language = {en} } @article{HauffeRathAgyapongetal.2022, author = {Hauffe, Robert and Rath, Michaela and Agyapong, Wilson and Jonas, Wenke and Vogel, Heike and Schulz, Tim Julius and Schwarz, Maria and Kipp, Anna Patricia and Bl{\"u}her, Matthias and Kleinridders, Andr{\´e}}, title = {Obesity Hinders the Protective Effect of Selenite Supplementation on Insulin Signaling}, series = {Antioxidants}, volume = {11}, journal = {Antioxidants}, edition = {5}, publisher = {MDPI}, address = {Basel, Schweiz}, issn = {2076-3921}, doi = {10.3390/antiox11050862}, pages = {1 -- 16}, year = {2022}, abstract = {The intake of high-fat diets (HFDs) containing large amounts of saturated long-chain fatty acids leads to obesity, oxidative stress, inflammation, and insulin resistance. The trace element selenium, as a crucial part of antioxidative selenoproteins, can protect against the development of diet-induced insulin resistance in white adipose tissue (WAT) by increasing glutathione peroxidase 3 (GPx3) and insulin receptor (IR) expression. Whether selenite (Se) can attenuate insulin resistance in established lipotoxic and obese conditions is unclear. We confirm that GPX3 mRNA expression in adipose tissue correlates with BMI in humans. Cultivating 3T3-L1 pre-adipocytes in palmitate-containing medium followed by Se treatment attenuates insulin resistance with enhanced GPx3 and IR expression and adipocyte differentiation. However, feeding obese mice a selenium-enriched high-fat diet (SRHFD) only resulted in a modest increase in overall selenoprotein gene expression in WAT in mice with unaltered body weight development, glucose tolerance, and insulin resistance. While Se supplementation improved adipocyte morphology, it did not alter WAT insulin sensitivity. However, mice fed a SRHFD exhibited increased insulin content in the pancreas. Overall, while selenite protects against palmitate-induced insulin resistance in vitro, obesity impedes the effect of selenite on insulin action and adipose tissue metabolism in vivo.}, language = {en} } @article{VojtaSkinnerMetzler2019, author = {Vojta, Thomas and Skinner, Sarah and Metzler, Ralf}, title = {Probability density of the fractional Langevin equation with reflecting walls}, series = {Physical review : E, Statistical, nonlinear and soft matter physics}, volume = {100}, journal = {Physical review : E, Statistical, nonlinear and soft matter physics}, number = {4}, publisher = {American Physical Society}, address = {College Park}, issn = {2470-0045}, doi = {10.1103/PhysRevE.100.042142}, pages = {11}, year = {2019}, abstract = {We investigate anomalous diffusion processes governed by the fractional Langevin equation and confined to a finite or semi-infinite interval by reflecting potential barriers. As the random and damping forces in the fractional Langevin equation fulfill the appropriate fluctuation-dissipation relation, the probability density on a finite interval converges for long times towards the expected uniform distribution prescribed by thermal equilibrium. In contrast, on a semi-infinite interval with a reflecting wall at the origin, the probability density shows pronounced deviations from the Gaussian behavior observed for normal diffusion. If the correlations of the random force are persistent (positive), particles accumulate at the reflecting wall while antipersistent (negative) correlations lead to a depletion of particles near the wall. We compare and contrast these results with the strong accumulation and depletion effects recently observed for nonthermal fractional Brownian motion with reflecting walls, and we discuss broader implications.}, language = {en} } @article{SposiniChechkinSenoetal.2018, author = {Sposini, Vittoria and Chechkin, Aleksei and Seno, Flavio and Pagnini, Gianni and Metzler, Ralf}, title = {Random diffusivity from stochastic equations}, series = {New Journal of Physics}, journal = {New Journal of Physics}, publisher = {Deutsche Physikalische Gesellschaft / Institute of Physics}, address = {Bad Honnef und London}, issn = {1367-2630}, doi = {10.1088/1367-2630/aab696}, pages = {1 -- 33}, year = {2018}, abstract = {A considerable number of systems have recently been reported in which Brownian yet non-Gaussian dynamics was observed. These are processes characterised by a linear growth in time of the mean squared displacement, yet the probability density function of the particle displacement is distinctly non-Gaussian, and often of exponential(Laplace) shape. This apparently ubiquitous behaviour observed in very different physical systems has been interpreted as resulting from diffusion in inhomogeneous environments and mathematically represented through a variable, stochastic diffusion coefficient. Indeed different models describing a fluctuating diffusivity have been studied. Here we present a new view of the stochastic basis describing time dependent random diffusivities within a broad spectrum of distributions. Concretely, our study is based on the very generic class of the generalised Gamma distribution. Two models for the particle spreading in such random diffusivity settings are studied. The first belongs to the class of generalised grey Brownian motion while the second follows from the idea of diffusing diffusivities. The two processes exhibit significant characteristics which reproduce experimental results from different biological and physical systems. We promote these two physical models for the description of stochastic particle motion in complex environments.}, language = {en} } @misc{BodrovaChechkinCherstvyetal.2015, author = {Bodrova, Anna and Chechkin, Aleksei and Cherstvy, Andrey G. and Metzler, Ralf}, title = {Quantifying non-ergodic dynamics of force-free granular gases}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-85200}, year = {2015}, abstract = {Brownianmotion is ergodic in the Boltzmann-Khinchin sense that long time averages of physical observables such as the mean squared displacement provide the same information as the corresponding ensemble average, even at out-of-equilibrium conditions. This property is the fundamental prerequisite for single particle tracking and its analysis in simple liquids. We study analytically and by event-driven molecular dynamics simulations the dynamics of force-free cooling granular gases and reveal a violation of ergodicity in this Boltzmann-Khinchin sense as well as distinct ageing of the system. Such granular gases comprise materials such as dilute gases of stones, sand, various types of powders, or large molecules, and their mixtures are ubiquitous in Nature and technology, in particular in Space. We treat—depending on the physical-chemical properties of the inter-particle interaction upon their pair collisions—both a constant and a velocity-dependent (viscoelastic) restitution coefficient e. Moreover we compare the granular gas dynamics with an effective single particle stochastic model based on an underdamped Langevin equation with time dependent diffusivity. We find that both models share the same behaviour of the ensemble mean squared displacement (MSD) and the velocity correlations in the limit of weak dissipation. Qualitatively, the reported non-ergodic behaviour is generic for granular gases with any realistic dependence of e on the impact velocity of particles.}, language = {en} } @article{VinodCherstvyMetzleretal.2022, author = {Vinod, Deepak and Cherstvy, Andrey G. and Metzler, Ralf and Sokolov, Igor M.}, title = {Time-averaging and nonergodicity of reset geometric Brownian motion with drift}, series = {Physical review : E, Statistical, nonlinear and soft matter physics}, volume = {106}, journal = {Physical review : E, Statistical, nonlinear and soft matter physics}, number = {3}, publisher = {American Physical Society}, address = {College Park}, issn = {2470-0045}, doi = {10.1103/PhysRevE.106.034137}, pages = {36}, year = {2022}, abstract = {How do near-bankruptcy events in the past affect the dynamics of stock-market prices in the future? Specifically, what are the long-time properties of a time-local exponential growth of stock-market prices under the influence of stochastically occurring economic crashes? Here, we derive the ensemble- and time-averaged properties of the respective "economic" or geometric Brownian motion (GBM) with a nonzero drift exposed to a Poissonian constant-rate price-restarting process of "resetting." We examine-based both on thorough analytical calculations and on findings from systematic stochastic computer simulations-the general situation of reset GBM with a nonzero [positive] drift and for all special cases emerging for varying parameters of drift, volatility, and reset rate in the model. We derive and summarize all short- and long-time dependencies for the mean-squared displacement (MSD), the variance, and the mean time-averaged MSD (TAMSD) of the process of Poisson-reset GBM under the conditions of both rare and frequent resetting. We consider three main regions of model parameters and categorize the crossovers between different functional behaviors of the statistical quantifiers of this process. The analytical relations are fully supported by the results of computer simulations. In particular, we obtain that Poisson-reset GBM is a nonergodic stochastic process, with generally MSD(Delta) not equal TAMSD(Delta) and Variance(Delta) not equal TAMSD(Delta) at short lag times Delta and for long trajectory lengths T. We investigate the behavior of the ergodicity-breaking parameter in each of the three regions of parameters and examine its dependence on the rate of reset at Delta/T << 1. Applications of these theoretical results to the analysis of prices of reset-containing options are pertinent.}, language = {en} } @article{MunackKorupResentinietal.2014, author = {Munack, Henry and Korup, Oliver and Resentini, Alberto and Limonta, Mara and Garzanti, Eduardo and Bloethe, Jan H. and Scherler, Dirk and Wittmann, Hella and Kubik, Peter W.}, title = {Postglacial denudation of western Tibetan Plateau margin outpaced by long-term exhumation}, series = {Geological Society of America bulletin}, volume = {126}, journal = {Geological Society of America bulletin}, number = {11-12}, publisher = {American Institute of Physics}, address = {Boulder}, issn = {0016-7606}, doi = {10.1130/B30979.1}, pages = {1580 -- 1594}, year = {2014}, abstract = {The Indus River, one of Asia's premier rivers, drains the western Tibetan Plateau and the Nanga Parbat syntaxis. These two areas juxtapose some of the lowest and highest topographic relief and commensurate denudation rates in the Himalaya-Tibet orogen, respectively, yet the spatial pattern of denudation rates upstream of the syntaxis remains largely unclear, as does the way in which major rivers drive headward incision into the Tibetan Plateau. We report a new inventory of Be-10-based basinwide denudation rates from 33 tributaries flanking the Indus River along a 320 km reach across the western Tibetan Plateau margin. We find that denudation rates of up to 110 mm k.y.(-1) in the Ladakh and Zanskar Ranges systematically decrease eastward to 10 mm k.y.(-1) toward the Tibetan Plateau. Independent results from bulk petrographic and heavy mineral analyses support this denudation gradient. Assuming that incision along the Indus exerts the base-level control on tributary denudation rates, our data show a systematic eastward decrease of landscape downwearing, reaching its minimum on the Tibetan Plateau. In contrast, denudation rates increase rapidly 150-200 km downstream of a distinct knick-point that marks the Tibetan Plateau margin in the Indus River longitudinal profile. We infer that any vigorous headward incision and any accompanying erosional waves into the interior of the plateau mostly concerned reaches well below this plateau margin. Moreover, reported long-term (>10(6) yr) exhumation rates from low-temperature chronometry of 0.1-0.75 mm yr(-1) consistently exceed our Be-10-derived denudation rates. With averaging time scales of 10(3)-10(4) yr for our denudation data, we report postglacial rates of downwearing in a tectonically idle landscape. To counterbalance this apparent mismatch, denudation rates must have been higher in the Quaternary during glacial-interglacial intervals.}, language = {en} } @article{FischerBrettinRoessneretal.2022, author = {Fischer, Melanie and Brettin, Jana and Roessner, Sigrid and Walz, Ariane and Fort, Monique and Korup, Oliver}, title = {Rare flood scenarios for a rapidly growing high-mountain city: Pokhara, Nepal}, series = {Natural Hazards and Earth System Sciences}, volume = {22}, journal = {Natural Hazards and Earth System Sciences}, edition = {9}, publisher = {Copernicus Publications}, address = {Katlenburg-Lindau}, issn = {1684-9981}, doi = {10.5194/nhess-22-3105-2022}, pages = {3105 -- 3123}, year = {2022}, abstract = {Pokhara (ca. 850 m a.s.l.), Nepal's second-largest city, lies at the foot of the Higher Himalayas and has more than tripled its population in the past 3 decades. Construction materials are in high demand in rapidly expanding built-up areas, and several informal settlements cater to unregulated sand and gravel mining in the Pokhara Valley's main river, the Seti Khola. This river is fed by the Sabche glacier below Annapurna III (7555 m a.s.l.), some 35 km upstream of the city, and traverses one of the steepest topographic gradients in the Himalayas. In May 2012 a sudden flood caused >70 fatalities and intense damage along this river and rekindled concerns about flood risk management. We estimate the flow dynamics and inundation depths of flood scenarios using the hydrodynamic model HEC-RAS (Hydrologic Engineering Center's River Analysis System). We simulate the potential impacts of peak discharges from 1000 to 10 000 m3 s-1 on land cover based on high-resolution Maxar satellite imagery and OpenStreetMap data (buildings and road network). We also trace the dynamics of two informal settlements near Kaseri and Yamdi with high potential flood impact from RapidEye, PlanetScope, and Google Earth imagery of the past 2 decades. Our hydrodynamic simulations highlight several sites of potential hydraulic ponding that would largely affect these informal settlements and sites of sand and gravel mining. These built-up areas grew between 3- and 20-fold, thus likely raising local flood exposure well beyond changes in flood hazard. Besides these drastic local changes, about 1 \% of Pokhara's built-up urban area and essential rural road network is in the highest-hazard zones highlighted by our flood simulations. Our results stress the need to adapt early-warning strategies for locally differing hydrological and geomorphic conditions in this rapidly growing urban watershed.}, language = {en} } @article{SafdariCherstvyChechkinetal.2017, author = {Safdari, Hadiseh and Cherstvy, Andrey G. and Chechkin, Aleksei and Bodrova, Anna and Metzler, Ralf}, title = {Aging underdamped scaled Brownian motion}, series = {Physical review : E, Statistical, nonlinear and soft matter physics}, volume = {95}, journal = {Physical review : E, Statistical, nonlinear and soft matter physics}, publisher = {American Physical Society}, address = {College Park}, issn = {2470-0045}, doi = {10.1103/PhysRevE.95.012120}, pages = {15}, year = {2017}, abstract = {We investigate both analytically and by computer simulations the ensemble- and time-averaged, nonergodic, and aging properties of massive particles diffusing in a medium with a time dependent diffusivity. We call this stochastic diffusion process the (aging) underdamped scaled Brownian motion (UDSBM). We demonstrate how the mean squared displacement (MSD) and the time-averaged MSD of UDSBM are affected by the inertial term in the Langevin equation, both at short, intermediate, and even long diffusion times. In particular, we quantify the ballistic regime for the MSD and the time-averaged MSD as well as the spread of individual time-averaged MSD trajectories. One of the main effects we observe is that, both for the MSD and the time-averaged MSD, for superdiffusive UDSBM the ballistic regime is much shorter than for ordinary Brownian motion. In contrast, for subdiffusive UDSBM, the ballistic region extends to much longer diffusion times. Therefore, particular care needs to be taken under what conditions the overdamped limit indeed provides a correct description, even in the long time limit. We also analyze to what extent ergodicity in the Boltzmann-Khinchin sense in this nonstationary system is broken, both for subdiffusive and superdiffusive UDSBM. Finally, the limiting case of ultraslow UDSBM is considered, with a mixed logarithmic and power-law dependence of the ensemble-and time-averaged MSDs of the particles. In the limit of strong aging, remarkably, the ordinary UDSBM and the ultraslow UDSBM behave similarly in the short time ballistic limit. The approaches developed here open ways for considering other stochastic processes under physically important conditions when a finite particle mass and aging in the system cannot be neglected.}, language = {en} } @article{BloetheKorup2013, author = {Bl{\"o}the, Jan Henrik and Korup, Oliver}, title = {Millennial lag times in the Himalayan sediment routing system}, series = {Earth \& planetary science letters}, volume = {382}, journal = {Earth \& planetary science letters}, number = {20}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0012-821X}, doi = {10.1016/j.epsl.2013.08.044}, pages = {38 -- 46}, year = {2013}, abstract = {Any understanding of sediment routing from mountain belts to their forelands and offshore sinks remains incomplete without estimates of intermediate storage that decisively buffers sediment yields from erosion rates, attenuates water and sediment fluxes, and protects underlying bedrock from incision. We quantify for the first time the sediment stored in > 38000 mainly postglacial Himalayan valley fills, based on an empirical volume-area scaling of valley-fill outlines automatically extracted from digital topographic data. The estimated total volume of 690(+452/-242) km(3) is mostly contained in few large valley fills > 1 km(3), while catastrophic mass wasting adds another 177(31) km(3). Sediment storage volumes are highly disparate along the strike of the orogen. Much of the Himalaya's stock of sediment is sequestered in glacially scoured valleys that provide accommodation space for similar to 44\% of the total volume upstream of the rapidly exhuming and incising syntaxes. Conversely, the step-like long-wave topography of the central Himalayas limits glacier extent, and thus any significant glacier-derived storage of sediment away from tectonic basins. We show that exclusive removal of Himalayan valley fills could nourish contemporary sediment flux from the Indus and Brahmaputra basins for > 1 kyr, though individual fills may attain residence times of > 100 kyr. These millennial lag times in the Himalayan sediment routing system may sufficiently buffer signals of short-term seismic as well as climatic disturbances, thus complicating simple correlation and interpretation of sedimentary archives from the Himalayan orogen, its foreland, and its submarine fan systems. (C) 2013 Elsevier B.V. All rights reserved.}, language = {en} } @article{SandevMetzlerChechkin2018, author = {Sandev, Trifce and Metzler, Ralf and Chechkin, Aleksei}, title = {From continuous time random walks to the generalized diffusion equation}, series = {Fractional calculus and applied analysis : an international journal for theory and applications}, volume = {21}, journal = {Fractional calculus and applied analysis : an international journal for theory and applications}, number = {1}, publisher = {De Gruyter}, address = {Berlin}, issn = {1311-0454}, doi = {10.1515/fca-2018-0002}, pages = {10 -- 28}, year = {2018}, abstract = {We obtain a generalized diffusion equation in modified or Riemann-Liouville form from continuous time random walk theory. The waiting time probability density function and mean squared displacement for different forms of the equation are explicitly calculated. We show examples of generalized diffusion equations in normal or Caputo form that encode the same probability distribution functions as those obtained from the generalized diffusion equation in modified form. The obtained equations are general and many known fractional diffusion equations are included as special cases.}, language = {en} } @misc{SchuckSchleicherJanssenetal.2020, author = {Schuck, Bernhard and Schleicher, Anja M. and Janssen, Christoph and Toy, Virginia G. and Dresen, Georg}, title = {Fault zone architecture of a large plate-bounding strike-slip fault}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1}, issn = {1866-8372}, doi = {10.25932/publishup-51244}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-512441}, pages = {32}, year = {2020}, abstract = {New Zealand's Alpine Fault is a large, platebounding strike-slip fault, which ruptures in large (M-w > 8) earthquakes. We conducted field and laboratory analyses of fault rocks to assess its fault zone architecture. Results reveal that the Alpine Fault Zone has a complex geometry, comprising an anastomosing network of multiple slip planes that have accommodated different amounts of displacement. This contrasts with the previous perception of the Alpine Fault Zone, which assumes a single principal slip zone accommodated all displacement. This interpretation is supported by results of drilling projects and geophysical investigations. Furthermore, observations presented here show that the young, largely unconsolidated sediments that constitute the footwall at shallow depths have a significant influence on fault gouge rheological properties and structure.}, language = {en} } @misc{JeonChechkinMetzler2014, author = {Jeon, Jae-Hyung and Chechkin, Aleksei and Metzler, Ralf}, title = {Scaled Brownian motion: a paradoxical process with a time dependent diffusivity for the description of anomalous diffusion}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-76302}, pages = {15811 -- 15817}, year = {2014}, abstract = {Anomalous diffusion is frequently described by scaled Brownian motion (SBM){,} a Gaussian process with a power-law time dependent diffusion coefficient. Its mean squared displacement is ?x2(t)? [similar{,} equals] 2K(t)t with K(t) [similar{,} equals] t[small alpha]-1 for 0 < [small alpha] < 2. SBM may provide a seemingly adequate description in the case of unbounded diffusion{,} for which its probability density function coincides with that of fractional Brownian motion. Here we show that free SBM is weakly non-ergodic but does not exhibit a significant amplitude scatter of the time averaged mean squared displacement. More severely{,} we demonstrate that under confinement{,} the dynamics encoded by SBM is fundamentally different from both fractional Brownian motion and continuous time random walks. SBM is highly non-stationary and cannot provide a physical description for particles in a thermalised stationary system. Our findings have direct impact on the modelling of single particle tracking experiments{,} in particular{,} under confinement inside cellular compartments or when optical tweezers tracking methods are used.}, language = {en} } @article{PatyniakLandgrafDzhumabaevaetal.2017, author = {Patyniak, Magda and Landgraf, Angela and Dzhumabaeva, Atyrgul and Abdrakhmatov, Kanatbek E. and Rosenwinkel, Swenja and Korup, Oliver and Preusser, Frank and Fohlmeister, Jens Bernd and Arrowsmith, J. Ramon and Strecker, Manfred}, title = {Paleoseismic Record of Three Holocene Earthquakes Rupturing the Issyk-Ata Fault near Bishkek, North Kyrgyzstan}, series = {Bulletin of the Seismological Society of America}, volume = {107}, journal = {Bulletin of the Seismological Society of America}, publisher = {Seismological Society of America}, address = {Albany}, issn = {0037-1106}, doi = {10.1785/0120170083}, pages = {2721 -- 2737}, year = {2017}, abstract = {The northern edge of the western central Tien Shan range is bounded by the Issyk-Ata fault situated south of Bishkek, the capital of Kyrgyzstan. Contraction in this thick-skinned orogen occurs with low-strain accumulation and long earthquake recurrence intervals. In the nineteenth to twentieth centuries, a sequence of large earthquakes with magnitudes between 6.9 and 8 affected the northern Tien Shan but left nearly the entire extent of the Issyk-Ata fault unruptured. Here, the only known historic earthquake ruptured in A.D. 1885 (M6.9) along the western end of the Issyk-Ata fault. Because earthquakes in low-strain regions often tend to cluster in time and may promote failure along nearby structures, the earthquake history of the northern Tien Shan represents an exceptional structural setting for studying fault behavior affected by an intraplate earthquake sequence. We present a paleoseismological study from one site (Belek) along the Issyk-Ata fault located east of the A.D. 1885 epicentral area. Our analysis combines a range of tools, including photogrammetry, differential Global Positioning System, 3D visualization, and age modeling with different dating methods (infrared stimulated luminescence, radiocarbon, U-series) to improve the reliability of an event chronology for the trench stratigraphy and fault geometry. We were able to distinguish three different surfacerupturing paleoearthquakes; these affected the area before 10.5 +/- 1.1 cal ka B.P., at similar to 5.6 +/- 1.0 cal ka B.P., and at similar to 630 +/- 100 cal B.P., respectively. Associated paleomagnitudes for the last two earthquakes range between M6.7 and 7.4, with a cumulative slip rate of 0.7 +/- 0.32 mm/yr. We did not find evidence for the A.D. 1885 event at Belek. Our study yielded two main overall results: first, it extends the regional historic and paleoseismic record; second, the documented rupture events along the Issyk-Ata fault suggest that this fault was not affected in its entirety; instead, these events indicate segmented rupture behavior.}, language = {en} } @article{BloetheRosenwinkelHoeseretal.2018, author = {Bl{\"o}the, Jan H. and Rosenwinkel, Swenja and Hoeser, Thorsten and Korup, Oliver}, title = {Rock-glacier dams in High Asia}, series = {Earth surface processes and landforms : the journal of the British Geomorphological Research Group}, volume = {44}, journal = {Earth surface processes and landforms : the journal of the British Geomorphological Research Group}, number = {3}, publisher = {Wiley}, address = {Hoboken}, issn = {0197-9337}, doi = {10.1002/esp.4532}, pages = {808 -- 824}, year = {2018}, abstract = {Rock glaciers in semiarid mountains contain large amounts of ice and might be important water stores aside from glaciers, lakes, and rivers. Yet whether and how rock glaciers interact with river channels in mountain valleys remains largely unresolved. We examine the potential for rock glaciers to block or disrupt river channels, using a new inventory of more than 2000 intact rock glaciers that we mapped from remotely sensed imagery in the Karakoram (KR), Tien Shan (TS), and Altai (ALT) mountains. We find that between 5\% and 14\% of the rock glaciers partly buried, blocked, diverted or constricted at least 95 km of mountain rivers in the entire study area. We use a Bayesian robust logistic regression with multiple topographic and climatic inputs to discern those rock glaciers disrupting mountain rivers from those with no obvious impacts. We identify elevation and potential incoming solar radiation (PISR), together with the size of feeder basins, as dominant predictors, so that lower-lying and larger rock glaciers from larger basins are more likely to disrupt river channels. Given that elevation and PISR are key inputs for modelling the regional distribution of mountain permafrost from the positions of rock-glacier toes, we infer that river-blocking rock glaciers may be diagnostic of non-equilibrated permafrost. Principal component analysis adds temperature evenness and wet-season precipitation to the controls that characterise rock glaciers impacting on rivers. Depending on the choice of predictors, the accuracy of our classification is moderate to good with median posterior area-under-the-curve values of 0.71-0.89. Clarifying whether rapidly advancing rock glaciers can physically impound rivers, or fortify existing dams instead, deserves future field investigation. We suspect that rock-glacier dams are conspicuous features that have a polygenetic history and encourage more research on the geomorphic coupling between permafrost lobes, river channels, and the sediment cascades of semiarid mountain belts. (c) 2018 John Wiley \& Sons, Ltd.}, language = {en} } @article{RosenwinkelKorupLandgrafetal.2015, author = {Rosenwinkel, Swenja and Korup, Oliver and Landgraf, Angela and Dzhumabaeva, Atyrgul}, title = {Limits to lichenometry}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {129}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2015.10.031}, pages = {229 -- 238}, year = {2015}, abstract = {Lichenometry is a straightforward and inexpensive method for dating Holocene rock surfaces. The rationale is that the diameter of the largest lichen scales with the age of the originally fresh rock surface that it colonised. The success of the method depends on finding the largest lichen diameters, a suitable lichen-growth model, and a robust calibration curve. Recent critique of the method motivates us to revisit the accuracy and uncertainties of lichenometry. Specifically, we test how well lichenometry is capable of resolving the ages of different lobes of large active rock glaciers in the Kyrgyz Tien Shan. We use a bootstrapped quantile regression to calibrate local growth curves of Xanthoria elegans, Aspicilia tianshanica, and Rhizocarpon geographicum, and report a nonlinear decrease in dating accuracy with increasing lichen diameter. A Bayesian type of an analysis of variance demonstrates that our calibration allows discriminating credibly between rock-glacier lobes of different ages despite the uncertainties tied to sample size and correctly identifying the largest lichen thalli. Our results also show that calibration error grows with lichen size, so that the separability of rock-glacier lobes of different ages decreases, while the tendency to assign coeval ages increases. The abundant young (<200 yr) specimen of fast-growing X elegans are in contrast with the fewer, slow-growing, but older (200-1500 yr) R. geographicum and A. tianshanica, and record either a regional reactivation of lobes in the past 200 years, or simply a censoring effect of lichen mortality during early phases of colonisation. The high variance of lichen sizes captures the activity of rock-glacier lobes, which is difficult to explain by regional climatic cooling or earthquake triggers alone. Therefore, we caution against inferring palaeoclimatic conditions from the topographic position of rock-glacier lobes. We conclude that lichenometry works better as a tool for establishing a relative, rather than an absolute, chronology of rock-glacier lobes in the northern Tien Shan. (C) 2015 Elsevier Ltd. All rights reserved.}, language = {en} } @article{MohrMangaWangetal.2017, author = {Mohr, Christian Heinrich and Manga, Michael and Wang, Chi-Yuen and Korup, Oliver}, title = {Regional changes in streamflow after a megathrust earthquake}, series = {Earth \& planetary science letters}, volume = {458}, journal = {Earth \& planetary science letters}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0012-821X}, doi = {10.1016/j.epsl.2016.11.013}, pages = {418 -- 428}, year = {2017}, abstract = {Moderate to large earthquakes can increase the amount of water feeding stream flows, mobilizing excess water from deep groundwater, shallow groundwater, or the vadose zone. Here we examine the regional pattern of streamflow response to the Maule M8.8 earthquake across Chile's diverse topographic and hydro-climatic gradients. We combine streamflow analyses with groundwater flow modeling and a random forest classifier, and find that, after the earthquake, at least 85 streams had a change in flow. Discharge mostly increased () shortly after the earthquake, liberating an excess water volume of >1.1 km3, which is the largest ever reported following an earthquake. Several catchments had increased discharge of >50 mm, locally exceeding seasonal streamflow discharge under undisturbed conditions. Our modeling results favor enhanced vertical permeability induced by dynamic strain as the most probable process explaining the observed changes at the regional scale. Supporting this interpretation, our random forest classification identifies peak ground velocity and elevation extremes as most important for predicting streamflow response. Given the mean recurrence interval of ∼25 yr for >M8.0 earthquakes along the Peru-Chile Trench, our observations highlight the role of earthquakes in the regional water cycle, especially in arid environments.}, language = {en} }