TY - JOUR
A1 - Abdalla, H.
A1 - Adam, R.
A1 - Aharonian, Felix A.
A1 - Benkhali, F. Ait
A1 - Angüner, Ekrem Oǧuzhan
A1 - Arcaro, C.
A1 - Armand, C.
A1 - Armstrong, T.
A1 - Ashkar, H.
A1 - Backes, M.
A1 - Baghmanyan, V.
A1 - Martins, V. Barbosa
A1 - Barnacka, A.
A1 - Barnard, M.
A1 - Becherini, Y.
A1 - Berge, D.
A1 - Bernlohr, K.
A1 - Bi, B.
A1 - Bottcher, M.
A1 - Boisson, C.
A1 - Bolmont, J.
A1 - de Lavergne, M. de Bony
A1 - Bordas, Pol
A1 - Breuhaus, M.
A1 - Brun, F.
A1 - Brun, P.
A1 - Bryan, M.
A1 - Buchele, M.
A1 - Bulik, T.
A1 - Bylund, T.
A1 - Caroff, S.
A1 - Carosi, A.
A1 - Casanova, Sabrina
A1 - Chand, T.
A1 - Chandra, S.
A1 - Chen, A.
A1 - Cotter, G.
A1 - Curylo, M.
A1 - Mbarubucyeye, J. Damascene
A1 - Davids, I. D.
A1 - Davies, J.
A1 - Deil, C.
A1 - Devin, J.
A1 - deWilt, P.
A1 - Dirson, L.
A1 - Djannati-Atai, A.
A1 - Dmytriiev, A.
A1 - Donath, A.
A1 - Doroshenko, V.
A1 - Duffy, C.
A1 - Dyks, J.
A1 - Egberts, Kathrin
A1 - Eichhorn, F.
A1 - Einecke, S.
A1 - Emery, G.
A1 - Ernenwein, J. -P.
A1 - Feijen, K.
A1 - Fegan, S.
A1 - Fiasson, A.
A1 - de Clairfontaine, G. Fichet
A1 - Fontaine, G.
A1 - Funk, S.
A1 - Fussling, Matthias
A1 - Gabici, S.
A1 - Gallant, Y. A.
A1 - Giavitto, G.
A1 - Giunti, L.
A1 - Glawion, D.
A1 - Glicenstein, J. F.
A1 - Gottschall, D.
A1 - Grondin, M. -H.
A1 - Hahn, J.
A1 - Haupt, M.
A1 - Hermann, G.
A1 - Hinton, J. A.
A1 - Hofmann, W.
A1 - Hoischen, Clemens
A1 - Holch, T. L.
A1 - Holler, M.
A1 - Horbe, M.
A1 - Horns, D.
A1 - Huber, D.
A1 - Jamrozy, M.
A1 - Jankowsky, D.
A1 - Jankowsky, F.
A1 - Jardin-Blicq, A.
A1 - Joshi, V.
A1 - Jung-Richardt, I.
A1 - Kasai, E.
A1 - Kastendieck, M. A.
A1 - Katarzynski, K.
A1 - Katz, U.
A1 - Khangulyan, D.
A1 - Khelifi, B.
A1 - Klepser, S.
A1 - Kluzniak, W.
A1 - Komin, Nu.
A1 - Konno, R.
A1 - Kosack, K.
A1 - Kostunin, D.
A1 - Kreter, M.
A1 - Lamanna, G.
A1 - Lemiere, A.
A1 - Lemoine-Goumard, M.
A1 - Lenain, J. -P.
A1 - Levy, C.
A1 - Lohse, T.
A1 - Lypova, I.
A1 - Mackey, J.
A1 - Majumdar, J.
A1 - Malyshev, D.
A1 - Malyshev, D.
A1 - Marandon, V.
A1 - Marchegiani, P.
A1 - Marcowith, Alexandre
A1 - Mares, A.
A1 - Marti-Devesa, G.
A1 - Marx, R.
A1 - Maurin, G.
A1 - Meintjes, P. J.
A1 - Meyer, M.
A1 - Mitchell, A.
A1 - Moderski, R.
A1 - Mohamed, M.
A1 - Mohrmann, L.
A1 - Montanari, A.
A1 - Moore, C.
A1 - Morris, P.
A1 - Moulin, Emmanuel
A1 - Muller, J.
A1 - Murach, T.
A1 - Nakashima, K.
A1 - Nayerhoda, A.
A1 - de Naurois, M.
A1 - Ndiyavala, H.
A1 - Niederwanger, F.
A1 - Niemiec, J.
A1 - Oakes, L.
A1 - O'Brien, Patrick
A1 - Odaka, H.
A1 - Ohm, S.
A1 - Olivera-Nieto, L.
A1 - Wilhelmi, E. de Ona
A1 - Ostrowski, M.
A1 - Oya, I.
A1 - Panter, M.
A1 - Panny, S.
A1 - Parsons, R. D.
A1 - Peron, G.
A1 - Peyaud, B.
A1 - Piel, Q.
A1 - Pita, S.
A1 - Poireau, V.
A1 - Noel, A. Priyana
A1 - Prokhorov, D. A.
A1 - Prokoph, H.
A1 - Puhlhofer, G.
A1 - Punch, M.
A1 - Quirrenbach, A.
A1 - Raab, S.
A1 - Rauth, R.
A1 - Reichherzer, P.
A1 - Reimer, A.
A1 - Reimer, O.
A1 - Remy, Q.
A1 - Renaud, M.
A1 - Rieger, F.
A1 - Rinchiuso, L.
A1 - Romoli, C.
A1 - Rowell, G.
A1 - Rudak, B.
A1 - Ruiz-Velasco, E.
A1 - Sahakian, V.
A1 - Sailer, S.
A1 - Sanchez, D. A.
A1 - Santangelo, A.
A1 - Sasaki, M.
A1 - Scalici, M.
A1 - Schussler, F.
A1 - Schutte, H. M.
A1 - Schwanke, U.
A1 - Schwemmer, S.
A1 - Seglar-Arroyo, M.
A1 - Senniappan, M.
A1 - Seyffert, A. S.
A1 - Shafi, N.
A1 - Shiningayamwe, K.
A1 - Simoni, R.
A1 - Sinha, A.
A1 - Sol, H.
A1 - Specovius, A.
A1 - Spencer, S.
A1 - Spir-Jacob, M.
A1 - Stawarz, L.
A1 - Sun, L.
A1 - Steenkamp, R.
A1 - Stegmann, C.
A1 - Steinmassl, S.
A1 - Steppa, C.
A1 - Takahashi, T.
A1 - Tavernier, T.
A1 - Taylor, A. M.
A1 - Terrier, R.
A1 - Tiziani, D.
A1 - Tluczykont, M.
A1 - Tomankova, L.
A1 - Trichard, C.
A1 - Tsirou, M.
A1 - Tuffs, R.
A1 - Uchiyama, Y.
A1 - van der Walt, D. J.
A1 - van Eldik, C.
A1 - van Rensburg, C.
A1 - van Soelen, B.
A1 - Vasileiadis, G.
A1 - Veh, J.
A1 - Venter, C.
A1 - Vincent, P.
A1 - Vink, J.
A1 - Volk, H. J.
A1 - Vuillaume, T.
A1 - Wadiasingh, Z.
A1 - Wagner, S. J.
A1 - Watson, J.
A1 - Werner, F.
A1 - White, R.
A1 - Wierzcholska, A.
A1 - Wong, Yu Wun
A1 - Yusafzai, A.
A1 - Zacharias, M.
A1 - Zanin, R.
A1 - Zargaryan, D.
A1 - Zdziarski, A. A.
A1 - Zech, Alraune
A1 - Zhu, S. J.
A1 - Ziegler, A.
A1 - Zorn, J.
A1 - Zouari, S.
A1 - Zywucka, N.
T1 - An extreme particle accelerator in the Galactic plane
BT - HESS J1826-130
JF - Astronomy and astrophysics : an international weekly journal
N2 - The unidentified very-high-energy (VHE; E > 0.1 TeV) gamma -ray source, HESS J1826-130, was discovered with the High Energy Stereoscopic System (HESS) in the Galactic plane. The analysis of 215 h of HESS data has revealed a steady gamma -ray flux from HESS J1826-130, which appears extended with a half-width of 0.21 degrees +/- 0.02
(stat)degrees
stat degrees +/- 0.05
(sys)degrees sys degrees . The source spectrum is best fit with either a power-law function with a spectral index Gamma = 1.78 +/- 0.10(stat) +/- 0.20(sys) and an exponential cut-off at 15.2
(+5.5)(-3.2) -3.2+5.5 TeV, or a broken power-law with Gamma (1) = 1.96 +/- 0.06(stat) +/- 0.20(sys), Gamma (2) = 3.59 +/- 0.69(stat) +/- 0.20(sys) for energies below and above E-br = 11.2 +/- 2.7 TeV, respectively. The VHE flux from HESS J1826-130 is contaminated by the extended emission of the bright, nearby pulsar wind nebula, HESS J1825-137, particularly at the low end of the energy spectrum. Leptonic scenarios for the origin of HESS J1826-130 VHE emission related to PSR J1826-1256 are confronted by our spectral and morphological analysis. In a hadronic framework, taking into account the properties of dense gas regions surrounding HESS J1826-130, the source spectrum would imply an astrophysical object capable of accelerating the parent particle population up to greater than or similar to 200 TeV. Our results are also discussed in a multiwavelength context, accounting for both the presence of nearby supernova remnants, molecular clouds, and counterparts detected in radio, X-rays, and TeV energies.
KW - ISM: supernova remnants
KW - ISM: clouds
KW - gamma rays: general
KW - gamma rays:
KW - ISM
Y1 - 2020
U6 - https://doi.org/10.1051/0004-6361/202038851
SN - 0004-6361
SN - 1432-0746
VL - 644
PB - EDP Sciences
CY - Les Ulis
ER -
TY - JOUR
A1 - Abdalla, Hassan E.
A1 - Adam, Remi
A1 - Aharonian, Felix A.
A1 - Benkhali, Faical Ait
A1 - Angüner, Ekrem Oǧuzhan
A1 - Arakawa, Masanori
A1 - Arcaro, C
A1 - Armand, Catherine
A1 - Armstrong, T.
A1 - Egberts, Kathrin
T1 - Very high energy γ-ray emission from two blazars of unknown redshift and upper limits on their distance
JF - Monthly Notices of the Royal Astronomical Society
N2 - We report on the detection of very high energy (VHE; E > 100 GeV) gamma-ray emission from the BL Lac objects KUV 00311-1938 and PKS 1440-389 with the High Energy Stereoscopic System (H.E.S.S.). H.E.S.S. observations were accompanied or preceded by multiwavelength observations with Fermi/LAT, XRT and UVOT onboard the Swift satellite, and ATOM. Based on an extrapolation of the Fermi/LAT spectrum towards the VHE gamma-ray regime, we deduce a 95 per cent confidence level upper limit on the unknown redshift of KUV 00311-1938 of z < 0.98 and of PKS 1440-389 of z < 0.53. When combined with previous spectroscopy results, the redshift of KUV 00311-1938 is constrained to 0.51 <= z < 0.98 and of PKS 1440-389 to 0.14 (sic) z < 0.53.
KW - BL Lacertae objects: individual
KW - galaxies: high-redshift
KW - gamma-rays: general
KW - Resolved and unresolved sources as a function of wavelength
Y1 - 2020
VL - 494
IS - 4
PB - Wiley-Blackwell
CY - Oxford
ER -
TY - GEN
A1 - Abdalla, Hassan E.
A1 - Adam, Remi
A1 - Aharonian, Felix A.
A1 - Benkhali, Faical Ait
A1 - Angüner, Ekrem Oǧuzhan
A1 - Arakawa, Masanori
A1 - Arcaro, C
A1 - Armand, Catherine
A1 - Armstrong, T.
A1 - Egberts, Kathrin
T1 - Very high energy γ-ray emission from two blazars of unknown redshift and upper limits on their distance
T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2 - We report on the detection of very high energy (VHE; E > 100 GeV) gamma-ray emission from the BL Lac objects KUV 00311-1938 and PKS 1440-389 with the High Energy Stereoscopic System (H.E.S.S.). H.E.S.S. observations were accompanied or preceded by multiwavelength observations with Fermi/LAT, XRT and UVOT onboard the Swift satellite, and ATOM. Based on an extrapolation of the Fermi/LAT spectrum towards the VHE gamma-ray regime, we deduce a 95 per cent confidence level upper limit on the unknown redshift of KUV 00311-1938 of z < 0.98 and of PKS 1440-389 of z < 0.53. When combined with previous spectroscopy results, the redshift of KUV 00311-1938 is constrained to 0.51 <= z < 0.98 and of PKS 1440-389 to 0.14 (sic) z < 0.53.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1202
KW - BL Lacertae objects: individual
KW - galaxies: high-redshift
KW - gamma-rays: general
KW - Resolved and unresolved sources as a function of wavelength
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-526000
SN - 1866-8372
IS - 4
ER -
TY - JOUR
A1 - Abdirashid, Hashim
A1 - Lenhard, Michael
T1 - Say it with double flowers
JF - Journal of experimental botany
N2 - Every year, lovers world-wide rely on mutants to show their feelings on Valentine's Day. This is because many of the most popular ornamental flowering plants have been selected to form extra petals at the expense of reproductive organs to enhance their attractiveness and aesthetic value to humans. This so-called 'double flower' (DF) phenotype, first described more than 2000 years ago (Meyerowitz et al., 1989) is present, for example, in many modern roses, carnations, peonies, and camellias. Gattolin et al. (2020) now identify a unifying explanation for the molecular basis of many of these DF cultivars.
KW - ABCE model
KW - APETALA2
KW - double flowers
KW - flower development
KW - homoeotic
KW - mutants
KW - microRNA172
Y1 - 2020
U6 - https://doi.org/10.1093/jxb/eraa109
SN - 0022-0957
SN - 1460-2431
VL - 71
IS - 9
SP - 2469
EP - 2471
PB - Oxford Univ. Press
CY - Oxford
ER -
TY - CHAP
A1 - Abramova, Olga
T1 - Does a smile open all doors?
BT - understanding the impact of appearance disclosure on accommodation sharing platforms
T2 - Proceedings of the 53rd Hawaii International Conference on System Sciences
N2 - Online photographs govern an individual’s choices across a variety of contexts. In sharing arrangements, facial appearance has been shown to affect the desire to collaborate, interest to explore a listing, and even willingness to pay for a stay. Because of the ubiquity of online images and their influence on social attitudes, it seems crucial to be able to control these aspects. The present study examines the effect of different photographic self-disclosures on the provider’s perceptions and willingness to accept a potential co-sharer. The findings from our experiment in the accommodation-sharing context suggest social attraction mediates the effect of photographic self-disclosures on willingness to host. Implications of the results for IS research and practitioners are discussed.
KW - The Sharing Economy
KW - airbnb
KW - online photographs
KW - self-disclosure
KW - sharing economy
KW - social attraction
Y1 - 2020
SN - 978-0-9981331-3-3
SP - 831
EP - 840
PB - HICSS Conference Office University of Hawaii at Manoa
CY - Honolulu
ER -
TY - JOUR
A1 - Adam, Maurits
A1 - Elsner, Birgit
T1 - The impact of salient action effects on 6-, 7-, and 11-month-olds’ goal-predictive gaze shifts for a human grasping action
JF - PLOS ONE
N2 - When infants observe a human grasping action, experience-based accounts predict that all infants familiar with grasping actions should be able to predict the goal regardless of additional agency cues such as an action effect. Cue-based accounts, however, suggest that infants use agency cues to identify and predict action goals when the action or the agent is not familiar. From these accounts, we hypothesized that younger infants would need additional agency cues such as a salient action effect to predict the goal of a human grasping action, whereas older infants should be able to predict the goal regardless of agency cues. In three experiments, we presented 6-, 7-, and 11-month-olds with videos of a manual grasping action presented either with or without an additional salient action effect (Exp. 1 and 2), or we presented 7-month-olds with videos of a mechanical claw performing a grasping action presented with a salient action effect (Exp. 3). The 6-month-olds showed tracking gaze behavior, and the 11-month-olds showed predictive gaze behavior, regardless of the action effect. However, the 7-month-olds showed predictive gaze behavior in the action-effect condition, but tracking gaze behavior in the no-action-effect condition and in the action-effect condition with a mechanical claw. The results therefore support the idea that salient action effects are especially important for infants' goal predictions from 7 months on, and that this facilitating influence of action effects is selective for the observation of human hands.
KW - attention
KW - eye movements
KW - infants perception
KW - mechanisms
KW - origins
Y1 - 2020
U6 - https://doi.org/10.1371/journal.pone.0240165
SN - 1932-6203
VL - 15
IS - 10
PB - Public Library of Science
CY - San Fransisco
ER -
TY - THES
A1 - Adamik, Verena
T1 - In Search of the Utopian States of America
BT - Intentional Communities in Novels of the Long Nineteenth Century
T2 - Palgrave Studies in Utopianism
N2 - This book endeavours to understand the seemingly direct link between utopianism and the USA, discussing novels that have never been brought together in this combination before, even though they all revolve around intentional communities: Imlay’s The Emigrants (1793), Hawthorne’s The Blithedale Romance (1852), Howland’s Papas Own Girl (1874), Griggs’s Imperium in Imperio (1899), and Du Bois’s The Quest of the Silver Fleece (1911). They relate nation and utopia not by describing perfect societies, but by writing about attempts to immediately live radically different lives. Signposting the respective communal history, the readings provide a literary perspective to communal studies, and add to a deeply necessary historicization for strictly literary approaches to US utopianism, and for studies that focus on Pilgrims/Puritans/Founding Fathers as utopian practitioners. This book therefore highlights how the authors evaluated the USA’s utopian potential and traces the nineteenth-century development of the utopian imagination from various perspectives.
KW - Gilbert Imlay
KW - Nathaniel Hawthorne
KW - Marie Howland
KW - Sutton E. Griggs
KW - W.E.B. Du Bois
KW - Utopian communities
KW - Intentional communities
KW - Utopia
KW - Nineteenth century
KW - National narrative
KW - Utopie
KW - Kommunen
KW - USA
Y1 - 2020
SN - 978-3-030-60278-9
SN - 978-3-030-60279-6
U6 - https://doi.org/10.1007/978-3-030-60279-6
PB - Palgrave Macmillan
CY - Cham
ER -
TY - JOUR
A1 - Adnan, Hassan Sami
A1 - Matthews, Sam
A1 - Hackl, M.
A1 - Das, P. P.
A1 - Manaswini, Manisha
A1 - Gadamsetti, S.
A1 - Filali, Maroua
A1 - Owoyele, Babajide
A1 - Santuber, Joaquín
A1 - Edelman, Jonathan
T1 - Human centered AI design for clinical monitoring and data management
JF - European journal of public health : official journal of the European Health Association
N2 - In clinical settings, significant resources are spent on data collection and monitoring patients' health parameters to improve decision-making and provide better care. With increased digitization, the healthcare sector is shifting towards implementing digital technologies for data management and in administration. New technologies offer better treatment opportunities and streamline clinical workflow, but the complexity can cause ineffectiveness, frustration, and errors. To address this, we believe digital solutions alone are not sufficient. Therefore, we take a human-centred design approach for AI development, and apply systems engineering methods to identify system leverage points. We demonstrate how automation enables monitoring clinical parameters, using existing non-intrusive sensor technology, resulting in more resources toward patient care. Furthermore, we provide a framework on digitization of clinical data for integration with data management.
Y1 - 2020
U6 - https://doi.org/10.1093/eurpub/ckaa165.225
SN - 1101-1262
SN - 1464-360X
VL - 30
IS - 5
SP - V86
EP - V86
PB - Oxford Univ. Press
CY - Oxford
ER -
TY - JOUR
A1 - Adnan, Hassan Sami
A1 - Srsic, Amanda
A1 - Venticich, Pete Milos
A1 - Townend, David M.R.
T1 - Using AI for mental health analysis and prediction in school surveys
JF - European journal of public health
N2 - Background:
Childhood and adolescence are critical stages of life for mental health and well-being. Schools are a key setting for mental health promotion and illness prevention. One in five children and adolescents have a mental disorder, about half of mental disorders beginning before the age of 14. Beneficial and explainable artificial intelligence can replace current paper- based and online approaches to school mental health surveys. This can enhance data acquisition, interoperability, data driven analysis, trust and compliance. This paper presents a model for using chatbots for non-obtrusive data collection and supervised machine learning models for data analysis; and discusses ethical considerations pertaining to the use of these models.
Methods:
For data acquisition, the proposed model uses chatbots which interact with students. The conversation log acts as the source of raw data for the machine learning. Pre-processing of the data is automated by filtering for keywords and phrases.
Existing survey results, obtained through current paper-based data collection methods, are evaluated by domain experts (health professionals). These can be used to create a test dataset to validate the machine learning models. Supervised learning
can then be deployed to classify specific behaviour and mental health patterns.
Results:
We present a model that can be used to improve upon current paper-based data collection and manual data analysis methods. An open-source GitHub repository contains necessary tools and components of this model. Privacy is respected through
rigorous observance of confidentiality and data protection requirements. Critical reflection on these ethics and law aspects is included in the project.
Conclusions:
This model strengthens mental health surveillance in schools. The same tools and components could be applied to other public health data. Future extensions of this model could also incorporate unsupervised learning to find clusters and patterns
of unknown effects.
KW - ethics
KW - artificial intelligence
KW - adolescent
KW - child
KW - confidentiality
KW - health personnel
KW - mental disorders
KW - mental health
KW - personal satisfaction
KW - privacy
KW - school (environment)
KW - statutes and laws
KW - public health medicine
KW - surveillance
KW - medical
KW - prevention
KW - datasets
KW - machine learning
KW - supervised machine learning
KW - data analysis
Y1 - 2020
U6 - https://doi.org/10.1093/eurpub/ckaa165.336
SN - 1101-1262
SN - 1464-360X
VL - 30
SP - V125
EP - V125
PB - Oxford Univ. Press
CY - Oxford [u.a.]
ER -
TY - JOUR
A1 - Aga-Barfknecht, Heja
A1 - Hallahan, Nicole
A1 - Gottmann, Pascal
A1 - Jähnert, Markus
A1 - Osburg, Sophie
A1 - Schulze, Gunnar
A1 - Kamitz, Anne
A1 - Arends, Danny
A1 - Brockmann, Gudrun
A1 - Schallschmidt, Tanja
A1 - Lebek, Sandra
A1 - Chadt, Alexandra
A1 - Al-Hasani, Hadi
A1 - Joost, Hans-Georg
A1 - Schürmann, Annette
A1 - Vogel, Heike
T1 - Identification of novel potential type 2 diabetes genes mediating beta-cell loss and hyperglycemia using positional cloning
JF - Frontiers in genetics
N2 - Type 2 diabetes (T2D) is a complex metabolic disease regulated by an interaction of genetic predisposition and environmental factors. To understand the genetic contribution in the development of diabetes, mice varying in their disease susceptibility were crossed with the obese and diabetes-prone New Zealand obese (NZO) mouse. Subsequent whole-genome sequence scans revealed one major quantitative trait loci (QTL),Nidd/DBAon chromosome 4, linked to elevated blood glucose and reduced plasma insulin and low levels of pancreatic insulin. Phenotypical characterization of congenic mice carrying 13.6 Mbp of the critical fragment of DBA mice displayed severe hyperglycemia and impaired glucose clearance at week 10, decreased glucose response in week 13, and loss of beta-cells and pancreatic insulin in week 16. To identify the responsible gene variant(s), further congenic mice were generated and phenotyped, which resulted in a fragment of 3.3 Mbp that was sufficient to induce hyperglycemia. By combining transcriptome analysis and haplotype mapping, the number of putative responsible variant(s) was narrowed from initial 284 to 18 genes, including gene models and non-coding RNAs. Consideration of haplotype blocks reduced the number of candidate genes to four (Kti12,Osbpl9,Ttc39a, andCalr4) as potential T2D candidates as they display a differential expression in pancreatic islets and/or sequence variation. In conclusion, the integration of comparative analysis of multiple inbred populations such as haplotype mapping, transcriptomics, and sequence data substantially improved the mapping resolution of the diabetes QTLNidd/DBA. Future studies are necessary to understand the exact role of the different candidates in beta-cell function and their contribution in maintaining glycemic control.
KW - type 2 diabetes
KW - beta-cell loss
KW - insulin
KW - positional cloning
KW - transcriptomics
KW - haplotype
Y1 - 2020
U6 - https://doi.org/10.3389/fgene.2020.567191
SN - 1664-8021
VL - 11
PB - Frontiers Media
CY - Lausanne
ER -
TY - JOUR
A1 - Agarwal, Ankit
A1 - Marwan, Norbert
A1 - Maheswaran, Rathinasamy
A1 - Öztürk, Ugur
A1 - Kurths, Jürgen
A1 - Merz, Bruno
T1 - Optimal design of hydrometric station networks based on complex network analysis
JF - Hydrology and Earth System Sciences
N2 - Hydrometric networks play a vital role in providing information for decision-making in water resource management. They should be set up optimally to provide as much information as possible that is as accurate as possible and, at the same time, be cost-effective. Although the design of hydrometric networks is a well-identified problem in hydrometeorology and has received considerable attention, there is still scope for further advancement. In this study, we use complex network analysis, defined as a collection of nodes interconnected by links, to propose a new measure that identifies critical nodes of station networks. The approach can support the design and redesign of hydrometric station networks. The science of complex networks is a relatively young field and has gained significant momentum over the last few years in different areas such as brain networks, social networks, technological networks, or climate networks. The identification of influential nodes in complex networks is an important field of research. We propose a new node-ranking measure – the weighted degree–betweenness (WDB) measure – to evaluate the importance of nodes in a network. It is compared to previously proposed measures used on synthetic sample networks and then applied to a real-world rain gauge network comprising 1229 stations across Germany to demonstrate its applicability. The proposed measure is evaluated using the decline rate of the network efficiency and the kriging error. The results suggest that WDB effectively quantifies the importance of rain gauges, although the benefits of the method need to be investigated in more detail.
KW - identifying influential nodes
KW - climate networks
KW - rainfall
KW - streamflow
KW - synchronization
KW - precipitation
KW - classification
KW - events
Y1 - 2020
U6 - https://doi.org/10.5194/hess-24-2235-2020
SN - 1027-5606
SN - 1607-7938
VL - 24
IS - 5
SP - 2235
EP - 2251
PB - Copernicus Publ.
CY - Göttingen
ER -
TY - GEN
A1 - Agarwal, Ankit
A1 - Marwan, Norbert
A1 - Maheswaran, Rathinasamy
A1 - Öztürk, Ugur
A1 - Kurths, Jürgen
A1 - Merz, Bruno
T1 - Optimal design of hydrometric station networks based on complex network analysis
T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2 - Hydrometric networks play a vital role in providing information for decision-making in water resource management. They should be set up optimally to provide as much information as possible that is as accurate as possible and, at the same time, be cost-effective. Although the design of hydrometric networks is a well-identified problem in hydrometeorology and has received considerable attention, there is still scope for further advancement. In this study, we use complex network analysis, defined as a collection of nodes interconnected by links, to propose a new measure that identifies critical nodes of station networks. The approach can support the design and redesign of hydrometric station networks. The science of complex networks is a relatively young field and has gained significant momentum over the last few years in different areas such as brain networks, social networks, technological networks, or climate networks. The identification of influential nodes in complex networks is an important field of research. We propose a new node-ranking measure – the weighted degree–betweenness (WDB) measure – to evaluate the importance of nodes in a network. It is compared to previously proposed measures used on synthetic sample networks and then applied to a real-world rain gauge network comprising 1229 stations across Germany to demonstrate its applicability. The proposed measure is evaluated using the decline rate of the network efficiency and the kriging error. The results suggest that WDB effectively quantifies the importance of rain gauges, although the benefits of the method need to be investigated in more detail.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 951
KW - identifying influential nodes
KW - climate networks
KW - rainfall
KW - streamflow
KW - synchronization
KW - precipitation
KW - classification
KW - events
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-471006
SN - 1866-8372
IS - 951
ER -
TY - RPRT
A1 - Aharon, Itzik
A1 - Brill, Antonia
A1 - Fonseca, Philip
A1 - Vandchali, Azin Alizadeh
A1 - Wendel, Nina
T1 - The Protection of Women Human Rights Defenders and their Collective Actions
T2 - Staat, Recht und Politik – Forschungs- und Diskussionspapiere
T2 - State, Law, and Politics - Research and Discussion Papers
N2 - This paper evaluates the construction of the rights of human rights defenders within international law and its shortcomings in protecting women. Human rights defenders have historically been defined on the basis of their actions as defenders. However, as Marxist-feminist scholar Silvia Federici contends, women are inherently politicised and, moreover, face obstacles to political action which are invisible to and untouchable by the law. Labour rights set an example of handling such a disadvantaged political position by placing vital importance on workers’ right to association and collective action. The paper closes with the suggestion that transposing this construction of rights to women would better protect women as human rights defenders while emphasising their capacity for self-determination in their political actions.
N2 - Dieses Papier bewertet die Konstruktion der Rechte von Menschenrechtsverteidigern innerhalb des Völkerrechts und ihre Mängel beim Schutz von Frauen. Menschenrechtsverteidiger wurden in der Vergangenheit auf der Grundlage ihrer Tätigkeit als Verteidiger definiert. Wie die marxistisch-feministische Wissenschaftlerin Silvia Federici behauptet, sind Frauen jedoch von Natur aus politisiert und sehen sich darüber hinaus Hindernissen für politisches Handeln gegenüber, die für das Gesetz unsichtbar und unantastbar sind. Die Arbeitsrechte sind ein Beispiel für den Umgang mit einer derart benachteiligten politischen Position, indem sie dem Recht der Arbeitnehmer auf Vereinigungsfreiheit und kollektive Aktionen entscheidende Bedeutung beimessen. Das Papier schließt mit dem Vorschlag, dass die Übertragung dieser Rechtskonstruktion auf Frauen Frauen als Menschenrechtsverteidigerinnen besser schützen und gleichzeitig ihre Fähigkeit zur Selbstbestimmung in ihrem politischen Handeln betonen würde.
T3 - Staat, Recht und Politik – Forschungs- und Diskussionspapiere = State, Law, and Politics - Research and Discussion Papers - 10
KW - Human Rights Defender
KW - Women's Rights
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-444278
IS - 10
PB - Universitätsverlag Potsdam
CY - Potsdam
ER -
TY - JOUR
A1 - Al-Naji, Majd
A1 - Schlaad, Helmut
A1 - Antonietti, Markus
T1 - New (and old) monomers from biorefineries to make polymer chemistry more sustainable
JF - Macromolecular rapid communications
N2 - This opinion article describes recent approaches to use the "biorefinery" concept to lower the carbon footprint of typical mass polymers, by replacing parts of the fossil monomers with similar or even the same monomer made from regrowing dendritic biomass. Herein, the new and green catalytic synthetic routes are for lactic acid (LA), isosorbide (IS), 2,5-furandicarboxylic acid (FDCA), and p-xylene (pXL). Furthermore, the synthesis of two unconventional lignocellulosic biomass derivable monomers, i.e., alpha-methylene-gamma-valerolactone (MeGVL) and levoglucosenol (LG), are presented. All those have the potential to enter in a cost-effective way, also the mass market and thereby recover lost areas for polymer materials. The differences of catalytic unit operations of the biorefinery are also discussed and the challenges that must be addressed along the synthesis path of each monomers.
KW - biodegradable polymers
KW - biorefineries
KW - carbohydrate‐ based
KW - monomers
KW - green polymers
KW - lignocellulosic biomass
Y1 - 2020
U6 - https://doi.org/10.1002/marc.202000485
SN - 1022-1336
SN - 1521-3927
VL - 42
IS - 3
PB - Wiley-VCH
CY - Weinheim
ER -
TY - GEN
A1 - Al-Naji, Majd
A1 - Schlaad, Helmut
A1 - Antonietti, Markus
T1 - New (and old) monomers from biorefineries to make polymer chemistry more sustainable
T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2 - This opinion article describes recent approaches to use the "biorefinery" concept to lower the carbon footprint of typical mass polymers, by replacing parts of the fossil monomers with similar or even the same monomer made from regrowing dendritic biomass. Herein, the new and green catalytic synthetic routes are for lactic acid (LA), isosorbide (IS), 2,5-furandicarboxylic acid (FDCA), and p-xylene (pXL). Furthermore, the synthesis of two unconventional lignocellulosic biomass derivable monomers, i.e., alpha-methylene-gamma-valerolactone (MeGVL) and levoglucosenol (LG), are presented. All those have the potential to enter in a cost-effective way, also the mass market and thereby recover lost areas for polymer materials. The differences of catalytic unit operations of the biorefinery are also discussed and the challenges that must be addressed along the synthesis path of each monomers.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1385
KW - biodegradable polymers
KW - biorefineries
KW - carbohydrate‐ based
KW - monomers
KW - green polymers
KW - lignocellulosic biomass
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-570614
SN - 1866-8372
IS - 3
ER -
TY - THES
A1 - AL-Rawi, Shadha
T1 - Biochemical studies to determine the role of Early Starvation 1 (ESV1) protein and its homologue Like-Early Starvation 1 (LESV) during starch degradation
N2 - Depending on the biochemical and biotechnical approach, the aim of this work was to understand the mechanism of protein-glucan interactions in regulation and control of starch degradation. Although starch degradation starts with the phosphorylation process, the mechanisms by which this process is controlling and adjusting starch degradation are not yet fully understood. Phosphorylation is a major process performed by the two dikinases enzymes α-glucan, water dikinase (GWD) and phosphoglucan water dikinase (PWD). GWD and PWD enzymes phosphorylate the starch granule surface; thereby stimulate starch degradation by hydrolytic enzymes. Despite these important roles for GWD and PWD, so far the biochemical processes by which these enzymes are able to regulate and adjust the rate of phosphate incorporation into starch during the degradation process haven‘t been understood. Recently, some proteins were found associated with the starch granule. Two of these proteins are named Early Starvation Protein 1 (ESV1) and its homologue Like-Early Starvation Protein 1 (LESV). It was supposed that both are involved in the control of starch degradation, but their function has not been clearly known until now. To understand how ESV1 and LESV-glucan interactions are regulated and affect the starch breakdown, it was analyzed the influence of ESV1 and LESV proteins on the phosphorylating enzyme GWD and PWD and hydrolysing enzymes ISA, BAM, and AMY. However, the analysis determined the location of LESV and ESV1 in the chloroplast stroma of Arabidopsis. Mass spectrometry data predicted ESV1and LESV proteins as a product of the At1g42430 and At3g55760 genes with a predicted mass of ~50 kDa and ~66 kDa, respectively. The ChloroP program predicted that ESV1 lacks the chloroplast transit peptide, but it predicted the first 56 amino acids N-terminal region as a chloroplast transit peptide for LESV. Usually, the transit peptide is processed during transport of the proteins into plastids. Given that this processing is critical, two forms of each ESV1 and LESV were generated and purified, a full-length form and a truncated form that lacks the transit peptide, namely, (ESV1and tESV1) and (LESV and tLESV), respectively. Both protein forms were included in the analysis assays, but only slight differences in glucan binding and protein action between ESV1 and tESV1 were observed, while no differences in the glucan binding and effect on the GWD and PWD action were observed between LESV and tLESV. The results revealed that the presence of the N-terminal is not massively altering the action of ESV1 or LESV. Therefore, it was only used the ESV1 and tLESV forms data to explain the function of both proteins.
However, the analysis of the results revealed that LESV and ESV1 proteins bind strongly at the starch granule surface. Furthermore, not all of both proteins were released after their incubation with starches after washing the granules with 2% [w/v] SDS indicates to their binding to the deeper layers of the granule surface. Supporting of this finding comes after the binding of both proteins to starches after removing the free glucans chains from the surface by the action of ISA and BAM. Although both proteins are capable of binding to the starch structure, only LESV showed binding to amylose, while in ESV1, binding was not observed. The alteration of glucan structures at the starch granule surface is essential for the incorporation of phosphate into starch granule while the phosphorylation of starch by GWD and PWD increased after removing the free glucan chains by ISA. Furthermore, PWD showed the possibility of starch phosphorylation without prephosphorylation by GWD.
Biochemical studies on protein-glucan interactions between LESV or ESV1 with different types of starch showed a potentially important mechanism of regulating and adjusting the phosphorylation process while the binding of LESV and ESV1 leads to altering the glucan structures of starches, hence, render the effect of the action of dikinases enzymes (GWD and PWD) more able to control the rate of starch degradation. Despite the presence of ESV1 which revealed an antagonistic effect on the PWD action as the PWD action was decreased without prephosphorylation by GWD and increased after prephosphorylation by GWD (Chapter 4), PWD showed a significant reduction in its action with or without prephosphorylation by GWD in the presence of ESV1 whether separately or together with LESV (Chapter 5). However, the presence of LESV and ESV1 together revealed the same effect compared to the effect of each one alone on the phosphorylation process, therefore it is difficult to distinguish the specific function between them. However, non-interactions were detected between LESV and ESV1 or between each of them with GWD and PWD or between GWD and PWD indicating the independent work for these proteins. It was also observed that the alteration of the starch structure by LESV and ESV1 plays a role in adjusting starch degradation rates not only by affecting the dikinases but also by affecting some of the hydrolysing enzymes since it was found that the presence of LESV and ESV1leads to the reduction of the action of BAM, but does not abolish it.
N2 - Ziel dieser Arbeit war es, den Mechanismus der Protein-Glucan-Wechselwirkungen bei der Regulation und Kontrolle des Stärkeabbaus zu verstehen. Der Stärkeabbau beginnt mit dem Phosphorylierungsprozess, der von den beiden Dikinasen, der a-Glucan, Wasserdikinase (GWD) und der Phosphoglucanwasserdikinase (PWD) durchgeführt wird. Kürzlich wurden einige Proteine gefunden, die mit dem Stärkegranulum assoziiert sind. Zwei dieser Proteine heißen Early Starvation 1 (ESV1) und das Homolog Like-Early Starvation (LESV), Es wurde vorgeschlagen, dass beide an der Kontrolle des Stärkeabbaus beteiligt sind, aber ihre Funktion ist bisher nicht bekannt.
Um zu verstehen, wie ESV1- und LESV-Glucan-Wechselwirkungen reguliert werden und den Stärkeabbau beeinflussen, wurde der Einfluss der beiden Proteine auf die Phosphorylierungsenzyme GWD und PWD, sowie die Hydrolasen isoamylase, betaamylase, und alpha-amylase ntersucht. Dabei ergab die Analyse, dass LESV und ESV1
nicht nur stark an der Oberfläche, sondern auch in den tieferen Schichten der Stärkegranula binden. Obwohl beide Proteine in der Lage sind, an die Stärkestruktur zu binden, zeigte nur LESV eine Bindung an Amylose, während für ESV1 keine Bindung beobachtet werden konnte.
Die Veränderung der Glucanstrukturen an der Oberfläche der Stärkekörner ist für den Einbau von Phosphat wesentlich, so nahm beispielsweise die Phosphorylierung der Stärke durch GWD und PWD nach Entfernung der freien Glucanketten mittels ISA zu. Darüber hinaus konnte ebenso gezeigt werden, dass PWD auch ohne eine
Präphosphorylierung durch GWD die Glucosyleinheiten innerhalb der Stärke phosphorylieren kann. Die Bindung von LESV und ESV1 führt zu einer Veränderung der Glucanstrukturen von Stärken, wodurch die Aktivität der Dikinasen (GWD und PWD) und somit die Geschwindigkeit des Stärkeabbaus wahrscheinlich besser gesteuert werden kann. Es wurden keine Wechselwirkungen zwischen LESV und ESV1 oder zwischen jedem von ihnen mit GWD und PWD oder zwischen GWD und PWD festgestellt, was auf die unabhängige Arbeit von diesen Proteinen hinweist. Es wurde auch beobachtet, dass die Modifikation der Stärkestruktur durch LESV und ESV1 eine Rolle bei der Anpassung der Stärkeabbauraten spielt, nicht nur durch Beeinflussung der Dikinasen, sondern auch durch die Beeinflussung einiger hydrolysierender Enzyme wie BAM. Den so zeigte die Amylase eine eindeutige Reduktion ihrer katalytischen Wirkung in Präsenz von LESV und ESV1.
Daraus resumierend kann davon ausgegangen werden, dass die beiden Proteine ESV1 und LESV für die Feinregulation des Stärkeabbaus von höchster Relevanz sind.
T2 - Biochemische Studien zur Bestimmung der Rolle des ESV1-Proteins
(Early Starvation 1) und seines Homologen Like-Early Starvation 1 (LESV) während des Stärkeabbaus
KW - Early starvation protein
KW - Like-Early starvation protein
KW - Glucan water dikinase
KW - Phosphoglucan water dikinase
KW - Phosphorylation process
KW - Starch metabolism
KW - Early Starvation 1
KW - Glucan-Wasser-Dikinase
KW - Like-Early Starvation 1
KW - Phosphoglucan-Wasser-Dikinase
KW - Phosphorylierungsprozess
KW - Stärkestoffwechsel
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-483956
ER -
TY - JOUR
A1 - Al-Saedy, Ammar Jaffar Muhesin
A1 - Tarchanov, Nikolaj Nikolaevič
T1 - A degree theory for Lagrangian boundary value problems
JF - Žurnal Sibirskogo Federalʹnogo Universiteta = Journal of Siberian Federal University; mathematics & physics
N2 - We study those nonlinear partial differential equations which appear as Euler-Lagrange equations of variational problems. On defining weak boundary values of solutions to such equations we initiate the theory of Lagrangian boundary value problems in spaces of appropriate smoothness. We also analyse if the concept of mapping degree of current importance applies to Lagrangian problems.
N2 - Мы изучаем те нелинейные уравнения с частными производными, которые возникают как уравнения Эйлера-Лагранжа вариационных задач. Определяя слабые граничные значения решений таких уравнений, мы инициируем теорию лагранжевых краевых задач в функциональных пространствах подходящей гладкости. Мы также анализируем, применяется ли современная концепция степени отображения к лагранжевым проблемам.
KW - nonlinear equations
KW - Lagrangian system
KW - weak boundary values
KW - quasilinear Fredholm operators
KW - mapping degree
Y1 - 2020
U6 - https://doi.org/10.17516/1997-1397-2020-13-1-5-25
SN - 1997-1397
SN - 2313-6022
VL - 13
IS - 1
SP - 5
EP - 25
PB - Sibirskij Federalʹnyj Universitet
CY - Krasnojarsk
ER -
TY - JOUR
A1 - Albert, Justin Amadeus
A1 - Owolabi, Victor
A1 - Gebel, Arnd
A1 - Brahms, Clemens Markus
A1 - Granacher, Urs
A1 - Arnrich, Bert
T1 - Evaluation of the Pose Tracking Performance of the Azure Kinect and Kinect v2 for Gait Analysis in Comparison with a Gold Standard
BT - A Pilot Study
JF - Sensors
N2 - Gait analysis is an important tool for the early detection of neurological diseases and for the assessment of risk of falling in elderly people. The availability of low-cost camera hardware on the market today and recent advances in Machine Learning enable a wide range of clinical and health-related applications, such as patient monitoring or exercise recognition at home. In this study, we evaluated the motion tracking performance of the latest generation of the Microsoft Kinect camera, Azure Kinect, compared to its predecessor Kinect v2 in terms of treadmill walking using a gold standard Vicon multi-camera motion capturing system and the 39 marker Plug-in Gait model. Five young and healthy subjects walked on a treadmill at three different velocities while data were recorded simultaneously with all three camera systems. An easy-to-administer camera calibration method developed here was used to spatially align the 3D skeleton data from both Kinect cameras and the Vicon system. With this calibration, the spatial agreement of joint positions between the two Kinect cameras and the reference system was evaluated. In addition, we compared the accuracy of certain spatio-temporal gait parameters, i.e., step length, step time, step width, and stride time calculated from the Kinect data, with the gold standard system. Our results showed that the improved hardware and the motion tracking algorithm of the Azure Kinect camera led to a significantly higher accuracy of the spatial gait parameters than the predecessor Kinect v2, while no significant differences were found between the temporal parameters. Furthermore, we explain in detail how this experimental setup could be used to continuously monitor the progress during gait rehabilitation in older people.
KW - motion capture
KW - evaluation
KW - human motion
KW - RGB-D cameras
KW - digital health
Y1 - 2020
U6 - https://doi.org/10.3390/s20185104
SN - 1424-8220
VL - 20
IS - 18
PB - MDPI
CY - Basel
ER -
TY - GEN
A1 - Albert, Justin Amadeus
A1 - Owolabi, Victor
A1 - Gebel, Arnd
A1 - Brahms, Clemens Markus
A1 - Granacher, Urs
A1 - Arnrich, Bert
T1 - Evaluation of the Pose Tracking Performance of the Azure Kinect and Kinect v2 for Gait Analysis in Comparison with a Gold Standard
BT - A Pilot Study
T2 - Postprints der Universität Potsdam : Reihe der Digital Engineering Fakultät
N2 - Gait analysis is an important tool for the early detection of neurological diseases and for the assessment of risk of falling in elderly people. The availability of low-cost camera hardware on the market today and recent advances in Machine Learning enable a wide range of clinical and health-related applications, such as patient monitoring or exercise recognition at home. In this study, we evaluated the motion tracking performance of the latest generation of the Microsoft Kinect camera, Azure Kinect, compared to its predecessor Kinect v2 in terms of treadmill walking using a gold standard Vicon multi-camera motion capturing system and the 39 marker Plug-in Gait model. Five young and healthy subjects walked on a treadmill at three different velocities while data were recorded simultaneously with all three camera systems. An easy-to-administer camera calibration method developed here was used to spatially align the 3D skeleton data from both Kinect cameras and the Vicon system. With this calibration, the spatial agreement of joint positions between the two Kinect cameras and the reference system was evaluated. In addition, we compared the accuracy of certain spatio-temporal gait parameters, i.e., step length, step time, step width, and stride time calculated from the Kinect data, with the gold standard system. Our results showed that the improved hardware and the motion tracking algorithm of the Azure Kinect camera led to a significantly higher accuracy of the spatial gait parameters than the predecessor Kinect v2, while no significant differences were found between the temporal parameters. Furthermore, we explain in detail how this experimental setup could be used to continuously monitor the progress during gait rehabilitation in older people.
T3 - Zweitveröffentlichungen der Universität Potsdam : Reihe der Digital Engineering Fakultät - 3
KW - motion capture
KW - evaluation
KW - human motion
KW - RGB-D cameras
KW - digital health
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-484130
IS - 3
ER -
TY - JOUR
A1 - Albrecht, Torsten
A1 - Winkelmann, Ricarda
A1 - Levermann, Anders
T1 - Glacial-cycle simulations of the Antarctic Ice Sheet with the Parallel Ice Sheet Model (PISM)
BT - part 2: parameter ensemble analysis
JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2 - The Parallel Ice Sheet Model (PISM) is applied to the Antarctic Ice Sheet over the last two glacial cycles (approximate to 210 000 years) with a resolution of 16 km. An ensemble of 256 model runs is analyzed in which four relevant model parameters have been systematically varied using full-factorial parameter sampling. Parameters and plausible parameter ranges have been identified in a companion paper (Albrecht et al., 2020) and are associated with ice dynamics, climatic forcing, basal sliding and bed deformation and represent distinct classes of model uncertainties. The model is scored against both modern and geologic data, including reconstructed grounding-line locations, elevation-age data, ice thickness, surface velocities and uplift rates. An aggregated score is computed for each ensemble member that measures the overall model-data misfit, including measurement uncertainty in terms of a Gaussian error model (Briggs and Tarasov, 2013). The statistical method used to analyze the ensemble simulation results follows closely the simple averaging method described in Pollard et al. (2016).
This analysis reveals clusters of best-fit parameter combinations, and hence a likely range of relevant model and boundary parameters, rather than individual best-fit parameters. The ensemble of reconstructed histories of Antarctic Ice Sheet volumes provides a score-weighted likely range of sea-level contributions since the Last Glacial Maximum (LGM) of 9.4 +/- 4.1m (or 6.5 +/- 2.0 x 10(6) km(3)), which is at the upper range of most previous studies. The last deglaciation occurs in all ensemble simulations after around 12 000 years before present and hence after the meltwater pulse 1A (MWP1a). Our ensemble analysis also provides an estimate of parametric uncertainty bounds for the present-day state that can be used for PISM projections of future sea-level contributions from the Antarctic Ice Sheet.
Y1 - 2020
U6 - https://doi.org/10.5194/tc-14-633-2020
SN - 1994-0416
SN - 1994-0424
VL - 14
IS - 2
SP - 633
EP - 656
PB - Copernicus Publ.
CY - Göttingen
ER -
TY - JOUR
A1 - Albrecht, Torsten
A1 - Winkelmann, Ricarda
A1 - Levermann, Anders
T1 - Glacial-cycle simulations of the Antarctic Ice Sheet with the Parallel Ice Sheet Model (PISM)
BT - Part 1: boundary conditions and climatic forcing
JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2 - Simulations of the glacial-interglacial history of the Antarctic Ice Sheet provide insights into dynamic threshold behavior and estimates of the ice sheet's contributions to global sea-level changes for the past, present and future. However, boundary conditions are weakly constrained, in particular at the interface of the ice sheet and the bedrock. Also climatic forcing covering the last glacial cycles is uncertain, as it is based on sparse proxy data.
We use the Parallel Ice Sheet Model (PISM) to investigate the dynamic effects of different choices of input data, e.g., for modern basal heat flux or reconstructions of past changes of sea level and surface temperature. As computational resources are limited, glacial-cycle simulations are performed using a comparably coarse model grid of 16 km and various parameterizations, e.g., for basal sliding, iceberg calving, or for past variations in precipitation and ocean temperatures. In this study we evaluate the model's transient sensitivity to corresponding parameter choices and to different boundary conditions over the last two glacial cycles and provide estimates of involved uncertainties. We also discuss isolated and combined effects of climate and sea-level forcing. Hence, this study serves as a "cookbook" for the growing community of PISM users and paleo-ice sheet modelers in general.
For each of the different model uncertainties with regard to climatic forcing, ice and Earth dynamics, and basal processes, we select one representative model parameter that captures relevant uncertainties and motivates corresponding parameter ranges that bound the observed ice volume at present. The four selected parameters are systematically varied in a parameter ensemble analysis, which is described in a companion paper.
Y1 - 2020
U6 - https://doi.org/10.5194/tc-14-599-2020
SN - 1994-0416
SN - 1994-0424
VL - 14
IS - 2
SP - 599
EP - 632
PB - Copernicus
CY - Göttingen
ER -
TY - JOUR
A1 - Aldiyarov, Abdurakhman
A1 - Sokolov, Dmitriy
A1 - Akylbayeva, Aigerim
A1 - Nurmukan, Assel
A1 - Tokmoldin, Nurlan
T1 - On thermal stability of cryovacuum deposited CH4+H2O films
JF - Low temperature physics
N2 - Whereas stable homogenous states of aqueous hydrocarbon solutions are typically observed at high temperatures and pressures far beyond the critical values corresponding to individual components, the stability of such system may be preserved upon transition into the region of metastable states at low temperatures and low pressures. This work is dedicated to the study of the thermal stability of a water-methane mixture formed by cryogenic vapor phase deposition. The obtained thin films were studied using vibrational spectroscopy in the temperature range of 16-180 K. During thermal annealing of the samples, characteristic vibrational C-H modes of methane were monitored alongside the chamber pressure to register both structural changes and desorption of the film material. The obtained results reveal that upon the co-deposition of methane and water, methane molecules appear both in non-bound and trapped states. The observed broadening of the characteristic C-H stretching mode at 3010 cm(-1) upon an increase in temperature of the sample from 16 to 90 K, followed by narrowing of the peak as the temperature is reduced back to 16 K, indicates localization of methane molecules within the water matrix at lower temperatures.
KW - molecular crystals
KW - water-methane films
KW - vibrational spectroscopy
KW - low
KW - temperature
KW - methane localization
Y1 - 2020
U6 - https://doi.org/10.1063/10.0002156
SN - 1063-777X
SN - 1090-6517
VL - 46
IS - 11
SP - 1121
EP - 1124
PB - American Institute of Physics
CY - Melville
ER -
TY - JOUR
A1 - Alexoudi, Xanthippi
A1 - Mallonn, Matthias
A1 - Keles, Engin
A1 - Poppenhäger, Katja
A1 - von Essen, Carolina
A1 - Strassmeier, Klaus
T1 - Role of the impact parameter in exoplanet transmission spectroscopy
JF - Astronomy and astrophysics : an international weekly journal
N2 - Context
Transmission spectroscopy is a promising tool for the atmospheric characterization of transiting exoplanets. Because the planetary signal is faint, discrepancies have been reported regarding individual targets.
Aims
We investigate the dependence of the estimated transmission spectrum on deviations of the orbital parameters of the star-planet system that are due to the limb-darkening effects of the host star. We describe how the uncertainty on the orbital parameters translates into an uncertainty on the planetary spectral slope.
Methods
We created synthetic transit light curves in seven different wavelength bands, from the near-ultraviolet to the near-infrared, and fit them with transit models parameterized by fixed deviating values of the impact parameter b. First, we performed a qualitative study to illustrate the effect by presenting the changes in the transmission spectrum slope with different deviations of b. Then, we quantified these variations by creating an error envelope (for centrally transiting, off-center, and grazing systems) based on a derived typical uncertainty on b from the literature. Finally, we compared the variations in the transmission spectra for different spectral types of host stars.
Results
Our simulations show a wavelength-dependent offset that is more pronounced at the blue wavelengths where the limb-darkening effect is stronger. This offset introduces a slope in the planetary transmission spectrum that becomes steeper with increasing b values. Variations of b by positive or negative values within its uncertainty interval introduce positive or negative slopes, thus the formation of an error envelope. The amplitude from blue optical to near-infrared wavelength for a typical uncertainty on b corresponds to one atmospheric pressure scale height and more. This impact parameter degeneracy is confirmed for different host types; K stars present prominently steeper slopes, while M stars indicate features at the blue wavelengths.
Conclusions
We demonstrate that transmission spectra can be hard to interpret, basically because of the limitations in defining a precise impact parameter value for a transiting exoplanet. This consequently limits a characterization of its atmosphere.
KW - planets and satellites: atmospheres
KW - planets and satellites: gaseous
KW - planets
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-605378
SN - 0004-6361
SN - 1432-0746
VL - 640
PB - EDP Sciences
CY - Les Ulis
ER -
TY - THES
A1 - Alirezaeizanjani, Zahra
T1 - Movement strategies of a multi-mode bacterial swimmer
N2 - Bacteria are one of the most widespread kinds of microorganisms that play essential roles in many biological and ecological processes. Bacteria live either as independent individuals or in organized communities. At the level of single cells, interactions between bacteria, their neighbors, and the surrounding physical and chemical environment are the foundations of microbial processes. Modern microscopy imaging techniques provide attractive and promising means to study the impact of these interactions on the dynamics of bacteria. The aim of this dissertation is to deepen our understanding four fundamental bacterial processes – single-cell motility, chemotaxis, bacterial interactions with environmental constraints, and their communication with neighbors – through a live cell imaging technique. By exploring these processes, we expanded our knowledge on so far unexplained mechanisms of bacterial interactions.
Firstly, we studied the motility of the soil bacterium Pseudomonas putida (P. putida), which swims through flagella propulsion, and has a complex, multi-mode swimming tactic. It was recently reported that P. putida exhibits several distinct swimming modes – the flagella can push and pull the cell body or wrap around it. Using a new combined phase-contrast and fluorescence imaging set-up, the swimming mode (push, pull, or wrapped) of each run phase was automatically recorded, which provided the full swimming statistics of the multi-mode swimmer. Furthermore, the investigation of cell interactions with a solid boundary illustrated an asymmetry for the different swimming modes; in contrast to the push and pull modes, the curvature of runs in wrapped mode was not affected by the solid boundary. This finding suggested that having a multi-mode swimming strategy may provide further versatility to react to environmental constraints.
Then we determined how P. putida navigates toward chemoattractants, i.e. its chemotaxis strategies. We found that individual run modes show distinct chemotactic responses in nutrition gradients. In particular, P. putida cells exhibited an asymmetry in their chemotactic responsiveness; the wrapped mode (slow swimming mode) was affected by the chemoattractant, whereas the push mode (fast swimming mode) was not. These results can be seen as a starting point to understand more complex chemotaxis strategies of multi-mode swimmers going beyond the well-known paradigm of Escherichia coli, that exhibits only one swimming mode.
Finally we considered the cell dynamics in a dense population. Besides physical interactions with their neighbors, cells communicate their activities and orchestrate their population behaviors via quorum-sensing. Molecules that are secreted to the surrounding by the bacterial cells, act as signals and regulate the cell population behaviour. We studied P. putida’s motility in a dense population by exposing the cells to environments with different concentrations of chemical signals. We found that higher amounts of chemical signals in the surrounding influenced the single-cell behaviourr, suggesting that cell-cell communications may also affect the flagellar dynamics.
In summary, this dissertation studies the dynamics of a bacterium with a multi-mode swimming tactic and how it is affected by the surrounding environment using microscopy imaging. The detailed description of the bacterial motility in fundamental bacterial processes can provide new insights into the ecology of microorganisms.
N2 - Bakterien gehören zu den am weitesten verbreiteten Mikroorganismen mit einer essentiellen Bedeutung in vielen biologischen und okologischen Prozessen. Bakterien können entweder als unabhängige Individuen oder in organisierten Gemeinschaften leben. Auf dem Level einer einzelnen Zelle sind Interaktionen zwischen Bakterien, ihren Nachbarn und des umgebenden physikalischen und chemischen Umwelt die Grundlage von mikrobiellen Prozessen. Mikroskopische Bildgebungs techniken bieten attraktive und vielversprechende Möglichkeiten den Einfluß dieses Interaktionen auf die Dynamik von Bakterien zu untersuchen. Das ziel dieser Dissertation ist es, vier fundamentale bakterielle Prozesse mittels Lebendzell-Mikroskopie besser zu verstehen – die Einzelzellbewegung, die Chemotaxis, die Wechselwirkungen der Bakterien mit der Umgebung und ihre Kommunikation mit Nachbarzellen. Durch die Untersuchung dieser Prozesse konnten wir das Wissen über die bisher ungeklärten Mechanismen der bakteriellen Interaktionen erweitern.
Als Erstes untersuchten wir die Fortbewegung des Bodenbakteriums Pseudomonas putida (P. putida), welches mit Hilfe eines Flagellenantriebs schwimmt und eine komplexe multi-mode Schwimmstrategie aufweist. Kürzlich wurde veröffentlich, dass P. putida mehrere unterschiedliche Schwimmmodi besitzt – die Flagellen können den Zellkörper nach vorne drücken (push) oder ziehen (pull) oder sich um ihn wickeln (wrap). Unter Verwendung einer neuen Methode, der kombinierten Phasenkontrast- und Fluoreszenzmikroskopie, konnten die Schwimmmodi (push, pull oder wrap) für jede Schwimmphase automatisch aufgenommen werden, was eine vollständige Schwimmstatistik des multi-mode Schwimmers lieferte. Weiterhin zeigte die Untersuchung von Interaktionen mit einer festen Grenzschicht eine Asymmetrie bezüglich der verschiedenen Schwimmmodi. Im Gegensatz zu push und pull, der wrapped Modus nicht durch die feste Grenzschicht beeinflusst. Diese Ergebnisse lassen vermuten, dass eine multi-mode Schwimmstrategie dem Bakterium weitere möglichkeiten bietet, sich an die Umgebungsbedingungen anzupassen.
Als Nächstes haben wir bestimmt, wie P. putida in Richtung eines Lockstoffes navigiert (Chemotaxis). Wir haben herausgefunden, dass einzelne Schwimmmodi eine unterschiedliche chemotaktische Antwort in Nährstoff-gradienten zeigen. P. putida besitzt eine Asymmetrie in seiner chemotaktischen Ansprechbarkeit: der wrapped Modus (langsamer Schwimmmodus) wird vom Lockstoff beeinflusst, der push Modus (schneller Schwimmmodus) hingegen nicht. Diese Ergebnisse können als Ausgangspunkt gesehen werden, um komplexere Chemotaxisstrategien von mulit-mode Schwimmern zu verstehen, die über das bekannte Musterbeispiel Escherichia coli hinaus gehen, des nur einen schwimmmodus aufweist.
schließend haben wir die Zelldynamik in dichten Kulturen untersucht. Neben den physikalischen Interaktionen mit den Nachbarzellen, kommunizieren zellen ihre Aktivitäten und organisieren ihr Populationsverhalten über quorum sensing. Moleküle, die von den Bakterienzellen in die Umgebung sekretiert werden, wirken als Signale und regulieren das Verhalten der Zellpopulation. Wir haben die Bewegung von P. putida in hoher Zelldichte untersucht, indem wir die Zellen unterschiedlichen Konzentrationen dieses Moleküle aussetzten. Wir haben festgestellt, dass größere Mengen dieser signalstoffe in der Umgebung die Einzelzelldynamik beeinflusst haben. Dies lässt uns vermuten, dass sich die Zell-Zell-Kommunikation auch auf die Flagellendynamik auswirkt.
Zusammenfassend zeigt diese Dissertation mittels Mikroskopie die Dynamik von einem Bakterium mit multi-mode Schwimmstrategie und wie die umgebende Umwelt diese Dynamik beeinflußt. Die detaillierte Beschreibung der Bakterienmotilität in grundlegenden bakteriellen Prozessen kann neue Erkenntnisse für die ökologie der Mikroorganismen bringen.
T2 - Bewegungsstrategien von bakteriellenmulti-mode Schwimmern
KW - Single-cell motility
KW - Einzelzellbewegung
KW - Chemotaxis
KW - Chemotaxis
KW - Flagellen
KW - Flagella
KW - Bacteria
KW - Bakterien
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-475806
ER -
TY - GEN
A1 - Alirezaeizanjani, Zahra
A1 - Großmann, Robert
A1 - Pfeifer, Veronika
A1 - Hintsche, Marius
A1 - Beta, Carsten
T1 - Chemotaxis strategies of bacteria with multiple run modes
T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2 - Bacterial chemotaxis-a fundamental example of directional navigation in the living world-is key to many biological processes, including the spreading of bacterial infections. Many bacterial species were recently reported to exhibit several distinct swimming modes-the flagella may, for example, push the cell body or wrap around it. How do the different run modes shape the chemotaxis strategy of a multimode swimmer? Here, we investigate chemotactic motion of the soil bacterium Pseudomonas putida as a model organism. By simultaneously tracking the position of the cell body and the configuration of its flagella, we demonstrate that individual run modes show different chemotactic responses in nutrition gradients and, thus, constitute distinct behavioral states. On the basis of an active particle model, we demonstrate that switching between multiple run states that differ in their speed and responsiveness provides the basis for robust and efficient chemotaxis in complex natural habitats.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1418
KW - instability
KW - flagellum
KW - exploit
KW - time
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-519098
SN - 1866-8372
IS - 22
ER -
TY - JOUR
A1 - Alirezaeizanjani, Zahra
A1 - Großmann, Robert
A1 - Pfeifer, Veronika
A1 - Hintsche, Marius
A1 - Beta, Carsten
T1 - Chemotaxis strategies of bacteria with multiple run modes
JF - Science advances
N2 - Bacterial chemotaxis-a fundamental example of directional navigation in the living world-is key to many biological processes, including the spreading of bacterial infections. Many bacterial species were recently reported to exhibit several distinct swimming modes-the flagella may, for example, push the cell body or wrap around it. How do the different run modes shape the chemotaxis strategy of a multimode swimmer? Here, we investigate chemotactic motion of the soil bacterium Pseudomonas putida as a model organism. By simultaneously tracking the position of the cell body and the configuration of its flagella, we demonstrate that individual run modes show different chemotactic responses in nutrition gradients and, thus, constitute distinct behavioral states. On the basis of an active particle model, we demonstrate that switching between multiple run states that differ in their speed and responsiveness provides the basis for robust and efficient chemotaxis in complex natural habitats.
KW - exploit
KW - flagellum
KW - instability
KW - time
Y1 - 2020
U6 - https://doi.org/10.1126/sciadv.aaz6153
SN - 2375-2548
VL - 6
IS - 22
PB - American Association for the Advancement of Science
CY - Washington
ER -
TY - JOUR
A1 - Allroggen, Niklas
A1 - Beiter, Daniel
A1 - Tronicke, Jens
T1 - Ground-penetrating radar monitoring of fast subsurface processes
JF - Geophysics
N2 - Earth and environmental sciences rely on detailed information about subsurface processes. Whereas geophysical techniques typically provide highly resolved spatial images, monitoring subsurface processes is often associated with enormous effort and, therefore, is usually limited to point information in time or space. Thus, the development of spatial and temporal continuous field monitoring methods is a major challenge for the understanding of subsurface processes. We have developed a novel method for ground-penetrating-radar (GPR) reflection monitoring of subsurface flow processes under unsaturated conditions and applied it to a hydrological infiltration experiment performed across a periglacial slope deposit in northwest Luxembourg. Our approach relies on a spatial and temporal quasicontinuous data recording and processing, followed by an attribute analysis based on analyzing differences between individual time steps. The results demonstrate the ability of time-lapse GPR monitoring to visualize the spatial and temporal dynamics of preferential flow processes with a spatial resolution in the order of a few decimeters and temporal resolution in the order of a few minutes. We observe excellent agreement with water table information originating from different boreholes. This demonstrates the potential of surface-based GPR reflection monitoring to observe the spatiotemporal dynamics of water movements in the subsurface. It provides valuable, and so far not accessible, information for example in the field of hydrology and pedology that allows studying the actual subsurface processes rather than deducing them from point information.
Y1 - 2020
U6 - https://doi.org/10.1190/GEO2019-0737.1
SN - 0016-8033
SN - 1942-2156
VL - 85
IS - 3
SP - A19
EP - A23
PB - Society of Exploration Geophysicists
CY - Tulsa
ER -
TY - THES
A1 - Amaechi, Mary Chimaobi
T1 - A'-movement dependencies and their reflexes in Igbo
N2 - In this thesis, I examine different A-bar movement dependencies in Igbo, a Benue-Congo language spoken in southern Nigeria. Movement dependencies are found in constructions where an element is moved to the left edge of the clause to express information-structural categories such as in questions, relativization and focus. I show that these constructions in Igbo are very uniform from a syntactic point of view. The constructions are built on two basic fronting operations: relativization and focus movement, and are biclausal. I further investigate several morphophonological effects that are found in these A-bar constructions. I propose that these effects are reflexes of movement that are triggered when an element is moved overtly in relativization or focus. This proposal helps to explain the tone patterns that have previously been assumed to be a property of relative clauses. The thesis adds to the growing body of tonal reflexes of A-bar movement reported for a few African languages. The thesis also provides an insight into the complementizer domain (C-domain) of Igbo.
N2 - In dieser Dissertation untersuche ich verschiedene syntaktische
A-quer-Bewegungsabhängigkeiten in Igbo, einer Benue-Kongo-Sprache, die im Süden Nigerias gesprochen wird. Bewegungsabhängigkeiten finden sich in Konstruktionen, in denen ein Element an den linken Satzrand bewegt wird, um informationsstrukturelle Kategorien auszudrücken, etwa in
Fragen, Relativsatzbildung und Fokussierung. Ich zeige, dass diese Konstruktionen in Igbo in Hinblick auf die Syntax sehr einheitlich sind. Die Konstruktionen bauen auf zwei grundlegenden Voranstellungsoperationen auf – Relativierung und Fokusbewegung – und sind biklausal. Außerdem untersuche ich verschiedene morphophonologische Effekte, die in diesen A-quer-Konstruktionen vorkommen. Ich schlage vor, dass die Effekte Ausdruck von Bewegung sind und dadurch ausgelöst werden, dass ein Element zum Zweck der Relativsatzbildung oder Fokussierung bewegt wird. Die Dissertation liefert einen weiteren Beleg für tonale Effekte von A-quer-Bewegung, die bereits für einige afrikanische Sprachen berichtet wurden. Die Arbeit gibt auch Aufschluss über die Komplementierer-Domäne (C-domain) in Igbo.
T2 - A'-Bewegungsabhängigkeiten und ihre Reflexe im Igbo
KW - A-bar movement
KW - clefts
KW - focus
KW - relativization
KW - Igbo
KW - A-quer-Bewegung
KW - Spaltsätze
KW - Fokus
KW - Relativsätze
KW - Igbo
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-471524
ER -
TY - JOUR
A1 - Amaechi, Mary Chimaobi
A1 - Georgi, Doreen
T1 - On optional wh-/focus fronting in Igbo
BT - a SYN-SEM-PHON interaction
JF - Zeitschrift für Sprachwissenschaft
N2 - This paper discusses surface optionality in focus fronting in the Benue-Congo language Igbo. A focused XP can occur in-situ or ex-situ. We argue that the optionality does not have its origins in the syntax: in fact, exactly one focused XP has to move to the designated focus position in the left periphery in the syntax. The alternation between in-situ and ex-situ rather arises at PF: either the lowest or the topmost copy of the focus chain is pronounced. The choice is determined by semantic-pragmatic factors, i. e., we see an interaction between PF and LF. This constitutes a challenge for a strict version of the Y-model of grammar.
KW - (A)over-bar-movement
KW - focus realization
KW - PF-optionality
KW - Y-model
KW - copy
KW - pronounciation
KW - Benue-Congo languages
Y1 - 2020
U6 - https://doi.org/10.1515/zfs-2020-2017
SN - 0721-9067
SN - 1613-3706
VL - 39
IS - 3
SP - 299
EP - 327
PB - De Gruyter
CY - Berlin
ER -
TY - JOUR
A1 - Amen, Rahma
A1 - Nagel, Rebecca
A1 - Hedt, Maximilian
A1 - Kirschbaum, Frank
A1 - Tiedemann, Ralph
T1 - Morphological differentiation in African weakly electric fish (genus Campylomormyrus) relates to substrate preferences
JF - Evolutionary Ecology
N2 - Under an ecological speciation scenario, the radiation of African weakly electric fish (genus Campylomormyrus) is caused by an adaptation to different food sources, associated with diversification of the electric organ discharge (EOD). This study experimentally investigates a phenotype-environment correlation to further support this scenario. Our behavioural experiments showed that three sympatric Campylomormyrus species with significantly divergent snout morphology differentially react to variation in substrate structure. While the short snout species (C. tamandua) exhibits preference to sandy substrate, the long snout species (C. rhynchophorus) significantly prefers a stone substrate for feeding. A third species with intermediate snout size (C. compressirostris) does not exhibit any substrate preference. This preference is matched with the observation that long-snouted specimens probe deeper into the stone substrate, presumably enabling them to reach prey more distant to the substrate surface. These findings suggest that the diverse feeding apparatus in the genus Campylomormyrus may have evolved in adaptation to specific microhabitats, i.e., substrate structures where these fish forage. Whether the parallel divergence in EOD is functionally related to this adaptation or solely serves as a prezygotic isolation mechanism remains to be elucidated.
KW - ecological speciation
KW - feeding behaviour
KW - electric fish
KW - trophic apparatus
KW - evolutionary ecology
Y1 - 2020
U6 - https://doi.org/10.1007/s10682-020-10043-3
SN - 0269-7653
SN - 1573-8477
VL - 34
IS - 3
SP - 427
EP - 437
PB - Springer Science
CY - Dordrecht
ER -
TY - GEN
A1 - Amen, Rahma
A1 - Nagel, Rebecca
A1 - Hedt, Maximilian
A1 - Kirschbaum, Frank
A1 - Tiedemann, Ralph
T1 - Morphological differentiation in African weakly electric fish (genus Campylomormyrus) relates to substrate preferences
T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2 - Under an ecological speciation scenario, the radiation of African weakly electric fish (genus Campylomormyrus) is caused by an adaptation to different food sources, associated with diversification of the electric organ discharge (EOD). This study experimentally investigates a phenotype-environment correlation to further support this scenario. Our behavioural experiments showed that three sympatric Campylomormyrus species with significantly divergent snout morphology differentially react to variation in substrate structure. While the short snout species (C. tamandua) exhibits preference to sandy substrate, the long snout species (C. rhynchophorus) significantly prefers a stone substrate for feeding. A third species with intermediate snout size (C. compressirostris) does not exhibit any substrate preference. This preference is matched with the observation that long-snouted specimens probe deeper into the stone substrate, presumably enabling them to reach prey more distant to the substrate surface. These findings suggest that the diverse feeding apparatus in the genus Campylomormyrus may have evolved in adaptation to specific microhabitats, i.e., substrate structures where these fish forage. Whether the parallel divergence in EOD is functionally related to this adaptation or solely serves as a prezygotic isolation mechanism remains to be elucidated.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1416
KW - ecological speciation
KW - feeding behaviour
KW - electric fish
KW - trophic apparatus
KW - evolutionary ecology
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-518714
SN - 1866-8372
IS - 3
ER -
TY - RPRT
A1 - Andres, Maximilian
A1 - Bruttel, Lisa Verena
A1 - Friedrichsen, Jana
T1 - Choosing between explicit cartel formation and tacit collusion – An experiment
T2 - CEPA Discussion Papers
N2 - Numerous studies investigate which sanctioning institutions prevent cartel formation but little is known as to how these sanctions work. We contribute to understanding the inner workings of cartels by studying experimentally the effect of sanctioning institutions on firms’ communication. Using machine learning to organize the chat communication into topics, we find that firms are significantly less likely to communicate explicitly about price fixing when sanctioning institutions are present. At the same time, average prices are lower when communication is less explicit. A mediation analysis suggests that sanctions are effective in hindering cartel formation not only because they introduce a risk of being fined but also by reducing the prevalence of explicit price communication.
T3 - CEPA Discussion Papers - 19
KW - cartel
KW - collusion
KW - communication
KW - machine learning
KW - experiment
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-473885
SN - 2628-653X
IS - 19
ER -
TY - THES
A1 - Aneley, Gedif Mulugeta
T1 - Drought tolerance prediction of potato by automatic phenotyping of morphological and physiological traits
T1 - Vorhersage von Trockentoleranz in Kartoffel durch automatische Phänotypisierung morphologischer und physiologischer Eigenschaften
N2 - Potato is the 4th most important food crop in the world. Especially in tropical and sub-tropical potato production, drought is a yield limiting factor. Potato is sensitive to water stress. Potato yield loss under water stress could be reduced by using tolerant varieties and adjusted agronomic practices. Direct selection for yield under water-stressed conditions requires long selection cycles. Thus, identification of markers for marker-assisted selection may speed up breeding. The objective of this thesis is to identify morphological markers for drought tolerance by continuously monitoring plant growth and canopy temperature with an automatic phenotyping system.
The phenotyping was performed in drought-stress experiments that were conducted in population A with 64 genotypes and population B with 21 genotypes in the screenhouse in 2015 and 2016 (population A) and in 2017 and 2018 (population B). Drought tolerance was quantified as deviation of the relative tuber starch yield from the experimental median (DRYM) and parent median (DRYMp). Relative tuber starch yield is starch yield under drought stress relative to the average starch yield of the respective cultivar under control conditions in the same experiment. The specific DRYM value was calculated based on the yield data of the same experiment or the global DRYM that was calculated from yield data derived from data combined over yeas of respective population or across multiple experiments including VALDIS and TROST experiments (2011-2016).
Analysis of variance found a significant effect of genotype on DRYM indicating that the tolerance variation required for marker identification was given in both populations.
Canopy growth was monitored continuously six times a day over five to ten weeks by a laser scanner system and yielded information on leaf area, plant height and leaf angle for population A and additionally on leaf inclination and light penetration depth for population B. Canopy temperature was measured 48 times a day over six to seven weeks by infrared thermometry in population B. From the continuous IRT surface temperature data set, the canopy temperature for each plant was selected by matching the time stamp of the IRT data with laser scanner data.
Mean, maximum, range and growth rate values were calculated from continuous laser scanner measurements of respective canopy parameters. Among the canopy parameters, the maximum and mean values in long-term stress conditions showed better correlation with DRYM values calculated in the same experiment than growth rate and diurnal range values. Therefore, drought tolerance index prediction was done from maximum and mean values of canopy parameters.
The tolerance index in specific experiment condition was linearly predicted by simple regression model from different single canopy parameters under long-term stress condition in population A (2016) and population B (2017 and 2018). Among the canopy parameters maximum light penetration depth (2017), mean leaf angle (2017, 2018, and 2016), mean leaf inclination or mean canopy temperature depression (2017 and 2018), maximum plant height (2017) were selected as tolerance predictors. However, no single parameters were sufficient to predict DRYM. Therefore, several independent parameters were integrated in a multiple regression model.
In multiple regression model, specific experiment DRYM values in population A was predicted from mean leaf angle (2016). In population B, specific tolerance could be predicted from maximum light penetration depth and mean leaf inclination (2017) and mean leaf inclination (2018) or mean canopy temperature depression and mean leaf angle (2018).
In data combined over season of population A, the multiple linear regression model selected maximum plant height and mean leaf angle as tolerance predictor. In Population B, mean leaf inclination was selected as tolerance predictor. However, in population A, the variation explained by the final model was too low.
Furthermore, the average tolerances respective to parent median (2011-2018) across FGH plants or all plants (FGH and field) were predicted from maximum plant height (population A) and maximum plant height and mean leaf inclination (population B). Altogether, canopy parameters could be used as markers for drought tolerance. Therefore, water stress breeding in potato could be speed up through using leaf inclination, light penetration depth, plant height and canopy temperature depression as markers for drought tolerance, especially in long-term stress conditions.
N2 - Die Kartoffel ist die viertwichtigste Nahrungspflanze der Welt. Besonders in den Tropen und Subtropen ist Trockenheit ein ertragsbegrenzender Faktor für die Kartoffelproduktion. Kartoffeln sind empfindlich gegen Trockenstress. Der Ertragsverlust von Kartoffeln unter Wasserstress könnte durch die Verwendung von toleranten Sorten und angepasste Anbaupraxis verringert werden. Die direkte Selektion für Ertrag unter Trockenstressbedingungen erfordert lange Selektionszyklen. Daher kann die Identifizierung von Markern für marker-assisted Selektion die Züchtung beschleunigen. Das Ziel dieser Arbeit ist es, morphologische Marker für Trockentoleranz mit Hilfe von kontinuierlichen Messungen von Pflanzenwachstum und Bestandstemperatur mittels automatischer Phänotypisierung zu identifizieren.
Die Phänotypisierung wurde in Trockenstressexperimenten durchgeführt, welche mit 64 Genotypen aus Population A und 21 Genotypen aus Population B in einem Foliengewächshaus in 2015 und 2016 (Population A) bzw. 2017 und 2018 (Population B) stattgefunden haben. Die Trockentoleranz wurde als Abweichung des relativen Stärkeertrags der Knollen vom experimentellen Median (DRYM) und dem Elternmedian (DRYMp) quantifiziert. Der relative Stärkeertrag ist der Stärkeertrag unter Trockenstress relativ zum mittleren Stärkeertrag der Sorte unter optimaler Bewässerung im gleichen Experiment. Der spezifische DRYM wurde auf der Basis der Ertragsdaten des gleichen Experiments berechnet oder der globale DRYM wurde auf der Basis der Ertragsdaten kombinierter Experimente aus mehreren Jahren für die gleiche Population oder für mehrere Experimente auch aus VALDIS und TROST (2011-2016) berechnet.
Die Varianzanalyse zeigte einen signifikanten Effekt des Genotyps auf DRYM, so dass die für die Identifizierung von Markern erforderliche Toleranzvariation in beiden Populationen gegeben war.
Die Bestandsentwicklung wurde mit einem Laserscanner-System kontinuierlich sechsmal täglich über fünf bis zehn Wochen gemessen und lieferte Informationen zu Blattfläche, Pflanzenhöhe und Blattwinkel für Population A sowie zusätzlich Blattneigung und Lichteinfalltiefe für Population B. Die Oberflächentemperatur wurde 48mal täglich für sechs bis sieben Wochen mittels Infrarot-Thermometrie in Population B gemessen. Aus dem kontinuierlichen IRT-Oberflächentemperatur-Datensatz wurde die Oberflächentemperatur jeder Pflanze bestimmt, indem die Zeitstempel der IRT-Daten mit denen der Laserscannerdaten abgeglichen wurden. Mittelwert, Maximum, Streubereich (range) und Wachstumsrate wurden für die Bestandsparameter der Laserscannermessungen bestimmt. Unter den Bestandsparametern zeigten die Maxima und Mittelwerte unter Langzeitstress die bessere Korrelation mit dem Toleranzindex DRYM, der aus dem gleichen Experiment berechnet wurde, als die Wachstumsrate und der Streubereich. Die Trockentoleranzprognose wurde daher aus den Maxima und Mittelwerte der Bestandsparameter gemacht.
Der Toleranzindex spezifischer Versuche wurde linear mit einem einfachen Regressionsmodell aus verschiedenen einzelnen Bestandparameters unter Langzeitstressbedingungen in Population A (2016) und Population (B) (2017 und 2018) vorhergesagt. Toleranz-Prognoseparameter wurden unter den Bestandparametern maximale Lichteinfalltiefe (2017), mittlerer Blattwinkel (2017, 2018 und 2016), mittlere Blattneigung und mittlere Oberflächentemperatur-Abweichung (2017 und 2018), maximale Pflanzenhöhe (2017) ausgewählt. Kein einzelner Parameter war jedoch ausreichend um DRYM vorherzusagen. Daher wurden mehrere unabhängige Parameter in einem multiplen Regressionsmodell integriert.
Im multiplen Regressionsmodel wurde der spezifische Experiment-DRYM in Population A aus dem mittleren Blattwinkel (2016) vorhergesagt. In Population B konnte die spezifische Toleranz aus der maximalen Lichteinfalltiefe, der maximalen Blattneigung (2017) und der mittleren Blattneigung (2018) oder der mittleren Oberflächentemperatur-Abweichung und dem mittleren Blattwinkel (2018) vorhergesagt werden.
In Daten aus mehreren Anbauperioden von Population A wählte das multiple lineare Regressionsmodel maximale Pflanzenhöhe und mittleren Blattwinkel als Prognoseparameter für Toleranz aus. In Population B wurde mittlere Blattneigung als Prognoseparameter für Toleranz ausgewählt. In Population A war jedoch die Variation, die durch das Endmodell erklärt wurde, zu niedrig.
Die mittlere Toleranz hinsichtlich des Medians der Eltern (2011 – 2018) über alle FGH Pflanzen oder alle Pflanzen (FGH und Feld) wurde ferner aus der maximalen Pflanzenhöhe (Population A) und der maximalen Pflanzenhöhe und mittleren Blattneigung (Population) vorhergesagt. Insgesamt konnten Bestandsparameter als Marker für Trockentoleranz genutzt werden. Dementsprechend könnte Trockenstresszucht in Kartoffeln beschleunigt werden, indem Blattneigung, Lichteinfalltiefe, Pflanzenhöhe und Oberflächentemperatur-Abweichung als Marker für Trockentoleranz, insbesondere unter Langzeitstressbedingungen, genutzt werden.
(Übersetzung Karin Köhl, 4.6.2020).
KW - Canopy parameters
KW - Drought tolerance
KW - DRYM
KW - Bestandsparameter
KW - Trockentoleranz
KW - DRYM
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-486836
ER -
TY - THES
A1 - Angelopoulos, Michael
T1 - Mechanisms of sub-aquatic permafrost evolution in Arctic coastal environments
BT - field observations and modelling of submerged ice-rich permafrost deposits and thermokarst lagoons in northeastern Siberia
N2 - Subsea permafrost is perennially cryotic earth material that lies offshore. Most submarine permafrost is relict terrestrial permafrost beneath the Arctic shelf seas, was inundated after the last glaciation, and has been warming and thawing ever since. It is a reservoir and confining layer for gas hydrates and has the potential to release greenhouse gases and affect global climate change. Furthermore, subsea permafrost thaw destabilizes coastal infrastructure. While numerous studies focus on its distribution and rate of thaw over glacial timescales, these studies have not been brought together and examined in their entirety to assess rates of thaw beneath the Arctic Ocean. In addition, there is still a large gap in our understanding of sub-aquatic permafrost processes on finer spatial and temporal scales. The degradation rate of subsea permafrost is influenced by the initial conditions upon submergence. Terrestrial permafrost that has already undergone warming, partial thawing or loss of ground ice may react differently to inundation by seawater compared to previously undisturbed ice-rich permafrost. Heat conduction models are sufficient to model the thaw of thick subsea permafrost from the bottom, but few studies have included salt diffusion for top-down chemical degradation in shallow waters characterized by mean annual cryotic conditions on the seabed. Simulating salt transport is critical for assessing degradation rates for recently inundated permafrost, which may accelerate in response to warming shelf waters, a lengthening open water season, and faster coastal erosion rates. In the nearshore zone, degradation rates are also controlled by seasonal processes like bedfast ice, brine injection, seasonal freezing under floating ice conditions and warm freshwater discharge from large rivers. The interplay of all these variables is complex and needs further research. To fill this knowledge gap, this thesis investigates sub-aquatic permafrost along the southern coast of the Bykovsky Peninsula in eastern Siberia. Sediment cores and ground temperature profiles were collected at a freshwater thermokarst lake and two thermokarst lagoons in 2017. At this site, the coastline is retreating, and seawater is inundating various types of permafrost: sections of ice-rich Pleistocene permafrost (Yedoma) cliffs at the coastline alternate with lagoons and lower elevation previously thawed and refrozen permafrost basins (Alases). Electrical resistivity surveys with floating electrodes were carried out to map ice-bearing permafrost and taliks (unfrozen zones in the permafrost, usually formed beneath lakes) along the diverse coastline and in the lagoons. Combined with the borehole data, the electrical resistivity results permit estimation of contemporary ice-bearing permafrost characteristics, distribution, and occasionally, thickness. To conceptualize possible geomorphological and marine evolutionary pathways to the formation of the observed layering, numerical models were applied. The developed model incorporates salt diffusion and seasonal dynamics at the seabed, including bedfast ice. Even along coastlines with mean annual non-cryotic boundary conditions like the Bykovsky Peninsula, the modelling results show that salt diffusion minimizes seasonal freezing of the seabed, leading to faster degradation rates compared to models without salt diffusion. Seasonal processes are also important for thermokarst lake to lagoon transitions because lagoons can generate cold hypersaline conditions underneath the ice cover. My research suggests that ice-bearing permafrost can form in a coastal lagoon environment, even under floating ice. Alas basins, however, may degrade more than twice as fast as Yedoma permafrost in the first several decades of inundation. In addition to a lower ice content compared to Yedoma permafrost, Alas basins may be pre-conditioned with salt from adjacent lagoons. Considering the widespread distribution of thermokarst in the Arctic, its integration into geophysical models and offshore surveys is important to quantify and understand subsea permafrost degradation and aggradation. Through numerical modelling, fieldwork, and a circum-Arctic review of subsea permafrost literature, this thesis provides new insights into sub-aquatic permafrost evolution in saline coastal environments.
KW - permafrost
KW - subsea
KW - submarine
KW - thermokarst
KW - lagoons
KW - salt diffusion
KW - electrical resistivity
Y1 - 2020
ER -
TY - JOUR
A1 - Angelopoulos, Michael
A1 - Overduin, Pier Paul
A1 - Westermann, Sebastian
A1 - Tronicke, Jens
A1 - Strauss, Jens
A1 - Schirrmeister, Lutz
A1 - Biskaborn, Boris
A1 - Liebner, Susanne
A1 - Maksimov, Georgii
A1 - Grigoriev, Mikhail N.
A1 - Grosse, Guido
T1 - Thermokarst lake to lagoon transitions in Eastern Siberia
BT - do submerged taliks refreeze?
JF - Journal of geophysical research : Earth surface
N2 - As the Arctic coast erodes, it drains thermokarst lakes, transforming them into lagoons, and, eventually, integrates them into subsea permafrost. Lagoons represent the first stage of a thermokarst lake transition to a marine setting and possibly more saline and colder upper boundary conditions. In this research, borehole data, electrical resistivity surveying, and modeling of heat and salt diffusion were carried out at Polar Fox Lagoon on the Bykovsky Peninsula, Siberia. Polar Fox Lagoon is a seasonally isolated water body connected to Tiksi Bay through a channel, leading to hypersaline waters under the ice cover. The boreholes in the center of the lagoon revealed floating ice and a saline cryotic bed underlain by a saline cryotic talik, a thin ice-bearing permafrost layer, and unfrozen ground. The bathymetry showed that most of the lagoon had bedfast ice in spring. In bedfast ice areas, the electrical resistivity profiles suggested that an unfrozen saline layer was underlain by a thick layer of refrozen talik. The modeling showed that thermokarst lake taliks can refreeze when submerged in saltwater with mean annual bottom water temperatures below or slightly above 0 degrees C. This occurs, because the top-down chemical degradation of newly formed ice-bearing permafrost is slower than the refreezing of the talik. Hence, lagoons may precondition taliks with a layer of ice-bearing permafrost before encroachment by the sea, and this frozen layer may act as a cap on gas migration out of the underlying talik.
KW - thermokarst lake
KW - talik
KW - lagoon
KW - subsea permafrost
KW - salt diffusion
KW - Siberia
Y1 - 2020
U6 - https://doi.org/10.1029/2019JF005424
SN - 2169-9003
SN - 2169-9011
VL - 125
IS - 10
PB - American Geophysical Union
CY - Washington
ER -
TY - JOUR
A1 - Annemarie, Ambühl
A1 - Weiss, Irene M.
A1 - Schierl, Petra
A1 - Schmitzer, Ulrich
A1 - Kirichenko, Alexander
A1 - Heinemann, Matthias
A1 - Weiß, Adrian
A1 - Esposito, Paolo
A1 - Grewing, Farouk F.
A1 - Merli, Elena
A1 - Feichtinger, Barbara
A1 - Seng, Helmut
A1 - Wieber, Anja
A1 - Schollmeyer, Patrick
A1 - Kranzdorf, Anna
A1 - Werner, Eva
A1 - Wöhrle, Georg
A1 - Brinker, Wolfram
A1 - Di Rocco, Emilia
A1 - Wesselmann, Katharina
A1 - Löbcke, Konrad
A1 - Benedetti, Ginevra
ED - Ambühl, Annemarie
T1 - tessellae – Birthday Issue for Christine Walde
T2 - thersites
N2 - This special birthday issue for Christine Walde, co-founder and co-editor of thersites, features contributions from colleagues and friends. The articles, essays, and book reviews, centering around the honoranda’s research interests as well as focusing on core topics of thersites, form a thematically varied mosaic (tessellae): innovative constructions of literary genres and poetics (especially bucolic, elegy, epic, and epigram), images of the city of Rome and its counterparts, sleep and dreams, history of classical scholarship, gender studies, and classical reception studies.
Y1 - 2020
U6 - https://doi.org/10.34679/thersites.vol11
SN - 2364-7612
VL - 2020
IS - 11
ER -
TY - JOUR
A1 - Apanasewicz, Anna
A1 - Groth, Detlef
A1 - Scheffler, Christiane
A1 - Hermanussen, Michael
A1 - Piosek, Magdalena
A1 - Wychowaniec, Patrycja
A1 - Babiszewska, Magdalena
A1 - Barbarska, Olga
A1 - Ziomkiewicz, Anna
T1 - Traumatized women’s infants are bigger than children of mothers without traumas
JF - Journal of biological and clinical anthropology : Anthropologischer Anzeiger
N2 - Life history theory predicts that experiencing stress during the early period of life will result in accelerated growth and earlier maturation. Indeed, animal and some human studies documented a faster pace of growth in the offspring of stressed mothers. Recent advances in epigenetics suggest that the effects of early developmental stress might be passed across the generations. However, evidence for such intergenerational transmission is scarce, at least in humans. Here we report the results of the study investigating the association between childhood trauma in mothers and physical growth in their children during the first months of life. Anthropometric and psychological data were collected from 99 mothers and their exclusively breastfed children at the age of 5 months. The mothers completed the Early Life Stress Questionnaire to assess childhood trauma. The questionnaire includes questions about the most traumatic events that they had experienced before the age of 12 years. Infant growth was evaluated based on the anthropometric measurements of weight, length, and head circumference. Also, to control for the size of maternal investment, the composition of breast milk samples taken at the time of infant anthropometric measurements was investigated. The children of mothers with higher early life stress tended to have higher weight and bigger head circumference. The association between infant anthropometrics and early maternal stress was not affected by breast milk composition, suggesting that the effect of maternal stress on infant growth was independent of the size of maternal investment. Our results demonstrate that early maternal trauma may affect the pace of growth in the offspring and, in consequence, lead to a faster life history strategy. This effect might be explained via changes in offspring epigenetics.
KW - maternal trauma
KW - early life trauma
KW - breastfed infant development
KW - POLS
Y1 - 2020
U6 - https://doi.org/10.1127/anthranz/2020/1285
SN - 0003-5548
SN - 2363-7099
VL - 77
IS - 5
SP - 359
EP - 374
PB - Schweizerbart science publishers
CY - Stuttgart
ER -
TY - JOUR
A1 - Apriyanto, Ardha
A1 - Tambunan, Van Basten
T1 - The complete mitochondrial genome of oil palm pollinating weevil, Elaeidobius kamerunicus Faust
BT - (Coleoptera : Curculionidae)
JF - Mitochondrial DNA: Part B
N2 - Elaeidobius kamerunicusis the most important insect pollinator in oil palm plantations. In this study, the mitochondrial genome (mitogenome) ofE. kamerunicus(17.729 bp), a member of the Curculionidae family, will be reported. The mitogenome consisted of 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), 2 ribosomal RNA genes (rRNAs), and a putative control region (CR). Phylogenetic analysis based on 13 protein-coding genes (PCGs) using maximum Likelihood (ML) methods indicated thatE. kamerunicusbelongs to the Curculionidae family. This mitochondrial genome provides essential information for understanding genetic populations, phylogenetics, molecular evolution, and other biological applications in this species.
KW - Mitogenome
KW - oil palm
KW - pollinator
KW - phylogeny
KW - weevil
Y1 - 2020
U6 - https://doi.org/10.1080/23802359.2020.1823899
SN - 2380-2359
VL - 5
IS - 3
SP - 3450
EP - 3452
PB - Routledge, Taylor & Francis Group
CY - Abingdon
ER -
TY - JOUR
A1 - Arazi, Hamid
A1 - Asadi, Abbas
A1 - Khalkhali, Farhood
A1 - Boullosa, Daniel
A1 - Hackney, Anthony C.
A1 - Granacher, Urs
A1 - Zouhal, Hassane
T1 - Association Between the Acute to Chronic Workload Ratio and Injury Occurrence in Young Male Team Soccer Players
BT - A Preliminary Study
N2 - This study aimed to investigate the relationship between the acute to chronic workload ratio (ACWR), based upon participant session rating of perceived exertion (sRPE), using two models [(1) rolling averages (ACWRRA); and (2) exponentially weighted moving averages (ACWREWMA)] and the injury rate in young male team soccer players aged 17.1 ± 0.7 years during a competitive mesocycle. Twenty-two players were enrolled in this study and performed four training sessions per week with 2 days of recovery and 1 match day per week. During each training session and each weekly match, training time and sRPE were recorded. In addition, training impulse (TRIMP), monotony, and strain were subsequently calculated. The rate of injury was recorded for each soccer player over a period of 4 weeks (i.e., 28 days) using a daily questionnaire. The results showed that over the course of the study, the number of non-contact injuries was significantly higher than that for contact injuries (2.5 vs. 0.5, p = 0.01). There were also significant positive correlations between sRPE and training time (r = 0.411, p = 0.039), ACWRRA (r = 0.47, p = 0.049), and ACWREWMA (r = 0.51, p = 0.038). In addition, small-to-medium correlations were detected between ACWR and non-contact injury occurrence (ACWRRA, r = 0.31, p = 0.05; ACWREWMA, r = 0.53, p = 0.03). Explained variance (r²) for non-contact injury was significantly greater using the ACWREWMA model (ranging between 21 and 52%) compared with ACWRRA (ranging between 17 and 39%). In conclusion, the results of this study showed that the ACWREWMA model is more sensitive than ACWRRA to identify non-contact injury occurrence in male team soccer players during a short period in the competitive season.
KW - training load
KW - rate of perceived exertion
KW - rolling averages
KW - weighted moving averages
KW - football
Y1 - 2020
U6 - https://doi.org/10.3389/fphys.2020.00608
SN - 1664-042X
VL - 11
PB - Frontiers Research Foundation
CY - Lausanne
ER -
TY - JOUR
A1 - Arazi, Hamid
A1 - Asadi, Abbas
A1 - Khalkhali, Farhood
A1 - Boullosa, Daniel
A1 - Hackney, Anthony C.
A1 - Granacher, Urs
A1 - Zouhal, Hassane
T1 - Association Between the Acute to Chronic Workload Ratio and Injury Occurrence in Young Male Team Soccer Players
BT - A Preliminary Study
JF - Frontiers in Physiology
N2 - This study aimed to investigate the relationship between the acute to chronic workload ratio (ACWR), based upon participant session rating of perceived exertion (sRPE), using two models [(1) rolling averages (ACWRRA); and (2) exponentially weighted moving averages (ACWREWMA)] and the injury rate in young male team soccer players aged 17.1 ± 0.7 years during a competitive mesocycle. Twenty-two players were enrolled in this study and performed four training sessions per week with 2 days of recovery and 1 match day per week. During each training session and each weekly match, training time and sRPE were recorded. In addition, training impulse (TRIMP), monotony, and strain were subsequently calculated. The rate of injury was recorded for each soccer player over a period of 4 weeks (i.e., 28 days) using a daily questionnaire. The results showed that over the course of the study, the number of non-contact injuries was significantly higher than that for contact injuries (2.5 vs. 0.5, p = 0.01). There were also significant positive correlations between sRPE and training time (r = 0.411, p = 0.039), ACWRRA (r = 0.47, p = 0.049), and ACWREWMA (r = 0.51, p = 0.038). In addition, small-to-medium correlations were detected between ACWR and non-contact injury occurrence (ACWRRA, r = 0.31, p = 0.05; ACWREWMA, r = 0.53, p = 0.03). Explained variance (r 2) for non-contact injury was significantly greater using the ACWREWMA model (ranging between 21 and 52%) compared with ACWRRA (ranging between 17 and 39%). In conclusion, the results of this study showed that the ACWREWMA model is more sensitive than ACWRRA to identify non-contact injury occurrence in male team soccer players during a short period in the competitive season.
KW - training load
KW - rate of perceived exertion
KW - rolling averages
KW - weighted moving averages
KW - football
Y1 - 2020
U6 - https://doi.org/10.3389/fphys.2020.00995
SN - 1664-042X
VL - 11
PB - Frontiers Research Foundation
CY - Lausanne
ER -
TY - GEN
A1 - Arazi, Hamid
A1 - Asadi, Abbas
A1 - Khalkhali, Farhood
A1 - Boullosa, Daniel
A1 - Hackney, Anthony C.
A1 - Granacher, Urs
A1 - Zouhal, Hassane
T1 - Association Between the Acute to Chronic Workload Ratio and Injury Occurrence in Young Male Team Soccer Players
BT - A Preliminary Study
T2 - Postprints der Universität Potsdam : Humanwissenschaftliche Reihe
N2 - This study aimed to investigate the relationship between the acute to chronic workload ratio (ACWR), based upon participant session rating of perceived exertion (sRPE), using two models [(1) rolling averages (ACWRRA); and (2) exponentially weighted moving averages (ACWREWMA)] and the injury rate in young male team soccer players aged 17.1 ± 0.7 years during a competitive mesocycle. Twenty-two players were enrolled in this study and performed four training sessions per week with 2 days of recovery and 1 match day per week. During each training session and each weekly match, training time and sRPE were recorded. In addition, training impulse (TRIMP), monotony, and strain were subsequently calculated. The rate of injury was recorded for each soccer player over a period of 4 weeks (i.e., 28 days) using a daily questionnaire. The results showed that over the course of the study, the number of non-contact injuries was significantly higher than that for contact injuries (2.5 vs. 0.5, p = 0.01). There were also significant positive correlations between sRPE and training time (r = 0.411, p = 0.039), ACWRRA (r = 0.47, p = 0.049), and ACWREWMA (r = 0.51, p = 0.038). In addition, small-to-medium correlations were detected between ACWR and non-contact injury occurrence (ACWRRA, r = 0.31, p = 0.05; ACWREWMA, r = 0.53, p = 0.03). Explained variance (r 2) for non-contact injury was significantly greater using the ACWREWMA model (ranging between 21 and 52%) compared with ACWRRA (ranging between 17 and 39%). In conclusion, the results of this study showed that the ACWREWMA model is more sensitive than ACWRRA to identify non-contact injury occurrence in male team soccer players during a short period in the competitive season.
T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 666
KW - training load
KW - rate of perceived exertion
KW - rolling averages
KW - weighted moving averages
KW - football
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-482330
SN - 1866-8364
IS - 666
ER -
TY - GEN
A1 - Arazi, Hamid
A1 - Asadi, Abbas
A1 - Khalkhali, Farhood
A1 - Boullosa, Daniel
A1 - Hackney, Anthony C.
A1 - Granacher, Urs
A1 - Zouhal, Hassane
T1 - Association Between the Acute to Chronic Workload Ratio and Injury Occurrence in Young Male Team Soccer Players
BT - A Preliminary Study
T2 - Postprints der Universität Potsdam : Humanwissenschaftliche Reihe
N2 - This study aimed to investigate the relationship between the acute to chronic workload ratio (ACWR), based upon participant session rating of perceived exertion (sRPE), using two models [(1) rolling averages (ACWRRA); and (2) exponentially weighted moving averages (ACWREWMA)] and the injury rate in young male team soccer players aged 17.1 ± 0.7 years during a competitive mesocycle. Twenty-two players were enrolled in this study and performed four training sessions per week with 2 days of recovery and 1 match day per week. During each training session and each weekly match, training time and sRPE were recorded. In addition, training impulse (TRIMP), monotony, and strain were subsequently calculated. The rate of injury was recorded for each soccer player over a period of 4 weeks (i.e., 28 days) using a daily questionnaire. The results showed that over the course of the study, the number of non-contact injuries was significantly higher than that for contact injuries (2.5 vs. 0.5, p = 0.01). There were also significant positive correlations between sRPE and training time (r = 0.411, p = 0.039), ACWRRA (r = 0.47, p = 0.049), and ACWREWMA (r = 0.51, p = 0.038). In addition, small-to-medium correlations were detected between ACWR and non-contact injury occurrence (ACWRRA, r = 0.31, p = 0.05; ACWREWMA, r = 0.53, p = 0.03). Explained variance (r²) for non-contact injury was significantly greater using the ACWREWMA model (ranging between 21 and 52%) compared with ACWRRA (ranging between 17 and 39%). In conclusion, the results of this study showed that the ACWREWMA model is more sensitive than ACWRRA to identify non-contact injury occurrence in male team soccer players during a short period in the competitive season.
T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 644
KW - training load
KW - rate of perceived exertion
KW - rolling averages
KW - weighted moving averages
KW - football
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-472961
SN - 1866-8364
IS - 644
ER -
TY - THES
A1 - Arentsen, Anke
T1 - Galactic archaeology with the oldest stars in the Milky Way
N2 - In einer dunklen Nacht kann man tausende Sterne sehen. All diese Sterne befinden sich innerhalb der Milchstraße, unsere Heimatgalaxie. Nicht alle Sterne sind gleich, sie können zum Beispiel unterschiedliche Größen, Massen, Temperaturen und Alter haben. Die schwereren Sterne leben (aus astronomischer Sicht) nicht lange, nur wenige Millionen Jahren, aber Sterne kleiner als die Sonne können mehr als zehn Milliarden Jahren alt werden. Kleine Sterne die ganz am Anfang des Universums entstanden sind leuchten immer noch. Diese uralten Sterne sind sehr hilfreich um mehr über das frühe Universum, die erste Sterne und die Geschichte der Milchstraße zu erfahren. Aber wie erkennt man uralte Sterne? Anhand ihrer chemischen Fingerabdrücke! Am Anfang des Universums gab es nur zwei chemische Elemente: Wasserstoff und Helium (und ein klein bisschen Lithium). Alle schwereren Elementen wie zum Beispiel Kohlenstoff, Kalzium und Eisen sind erst später innerhalb von Sternen und in Sternexplosionen entstanden. Je mehr Sternen geboren werden, sich entwickeln und explodieren, desto mehr chemische Elemente gibt es im Universum. Sterne die später entstehen werden mit einer größeren Menge an schweren Elementen, beziehungsweise einer größeren Metallizität, geboren. Im Bereich der Astronomie der sich „Galaktische Archäologie” nennt benutzt man Sterne mit unterschiedlichen Metallizitäten um die Geschichte der Milchstraße zu erforschen. In dieser Doktorarbeit liegt der Fokus auf den metallarmen Sterne, da man erwartet dass diese Sterne am ältesten sind und uns deswegen viel über die frühe Geschichte erzählen können.
Bis heute haben wir noch keinen metallfreien Stern entdeckt, aber die metallärmsten Sterne geben uns wichtige Einblicke in das Leben und Sterben der ersten Sterne. Viele von diesen ältesten, metallärmsten Sternen haben unerwartet viel Kohlenstoff im Vergleich zu zum Beispiel Eisen. Diese kohlenstoffreichen, metallarmen Sterne (CEMP Sterne) erzählen uns etwas über die allerersten Sterne im Universum: sie haben relativ viel Kohlenstoff produziert. Wenn wir uns die genauen chemischen Fingerabdrücke von CEMP Sterne angucken, erzählen sie uns noch viel mehr. Aber unsere Interpretation hängt von der Annahme ab, dass der chemische Fingerabdruck sich während des Lebens eines Sternes nicht geändert hat. In dieser Dissertation werden neue Daten präsentiert die zeigen dass diese Annahme vielleicht zu einfach ist: viele extrem metallarme CEMP Sterne befinden sich in Doppelsternsystemen. Interaktion zwischen zwei Sternen in einem Doppelsternsystem könnte die Oberfläche von CEMP Sternen verschmutzt haben. Zwar wurden die meisten CEMP Sterne höchstwahrscheinlich nicht verschmutzt, aber wir sollten vorsichtig sein mit unserer Interpretation.
Die CEMP Sterne und andere metallarme Sterne sind auch wichtig für unser Verständnis der frühen Geschichte der Milchstraße. Die meisten Forscher, die metallarme Sterne studieren, suchen diese Sterne im Halo der Milchstraße: einer riesigen, diffuse Komponente die ungefähr 1% der Sterne in unserer Galaxie enthält. Modelle sagen aber vorher dass die ältesten metallarmen Sterne sich im Zentrum der Milchstraße befinden (im „Bulge”). Das Zentrum ist leider, wegen großer Mengen Staub zwischen uns und dem Zentrum und einer überwältigenden Mehrheit an metallreichen Sternen, schwierig zu beobachten. Diese Dissertation präsentiert Ergebnisse des „Pristine Inner Galaxy Survey” (PIGS), einer neuen Himmelsdurchmusterung, die die ältesten Sterne im Bulge der Milchstraße sucht (und findet). PIGS benutzt Bilder mit einer Farbe, die für die Metallizität der Sterne empfindlich ist, und kann deswegen sehr effektiv die metallarmen Sterne aus Millionen anderer Sterne auswählen. Von interessanten Kandidaten wurden Spektren aufgenommen und mit zwei unabhängigen Methoden analysiert. Mit dieser Strategie hat PIGS die bislang größte Anzahl an metallarmen Sternen in der inneren Galaxie entdeckt. Ein neues Ergebnis aus den PIGS Daten ist, dass die metallärmeren Sterne langsamer um das Galaktische Zentrum drehen als die metallreichen Sterne, und dass sie mehr willkürliche Bewegung zeigen. Eine zweite wichtige Leistung von PIGS ist die Entdeckung von dutzenden CEMP Sternen in der innere Galaxie, wo vorher nur zwei bekannt waren.
Die neuen Ergebnisse aus dieser Dissertation helfen uns die ersten Sterne und die Geschichte der Milchstraße besser zu verstehen. Laufende und neue Himmelsdurchmusterungen in den nächsten Jahren werden uns noch viel mehr Informationen geben: es ist eine aufregende Zeit für die Galaktische Archäologie.
N2 - During a dark night, it is possible to observe thousands of stars by eye. All these stars are located within the Milky Way, our home. Not all stars are the same, they can have different sizes, masses, temperatures and ages. Heavy stars do not live long (in astronomical terms), only a few million years, but stars less massive than the Sun can get more than ten billion years old. Such small stars that formed in the beginning of the Universe still shine today. These ancient stars are very helpful to learn more about the early Universe, the First Stars and the history of the Milky Way. But how do you recognise an ancient star? Using their chemical fingerprints! In the beginning of the Universe, there were only two chemical elements: hydrogen and helium (and a tiny bit of lithium). All the heavier elements like carbon, calcium and iron were only made later within stars and their explosions. The amount of chemical elements in the Universe increases with the number of stars that are born, evolve and explode. Stars that form later are born with more heavy elements, or a greater metallicity. In the field of astronomy that is called “Galactic Archaeology”, stars of various metallicities are used to study the history of the Milky Way. In this doctoral thesis, the focus is on metal-poor stars because these are expected to be the oldest and can therefore tell us a lot about the early history of our Galaxy.
Until today, we still have not discovered a metal-free star. The most metal-poor stars, however, give us important insights in the lives and deaths of the First Stars. Many of the oldest, most metal-poor stars have an unexpectedly large amount of carbon, compared to for example iron. These carbon-enhanced metal-poor (CEMP) stars tell us something about the very first stars in the Universe: they somehow produced a lot of carbon. If we look at the precise chemical fingerprints of the CEMP stars, we can learn a lot more. But our interpretation depends on the assumption that the chemical fingerprint of a star does not change during its life. In this thesis, new data is presented that shows that this assumption may be too simple: many extremely metal-poor CEMP stars are members of binary systems. Interactions between two stars in a binary system can pollute the surface of the stars. Likely not all of the CEMP stars in binary systems were actually polluted, but we should be very careful in our interpretations of the fingerprints of these stars.
The CEMP stars and other metal-poor stars are also important for our understanding of the early history of the Milky Way. Most researchers who study metal-poor stars look for these stars in the halo of the Milky Way: a huge diffuse Galactic component containing about 1% of the stars in our Galaxy. However, models predict that the oldest metal-poor stars are located in the center of the Milky Way, in the bulge. The metal-poor inner Galaxy is unfortunately difficult to study due to large amounts of dust between us and the center and an overwhelming majority of metal-rich stars. This thesis presents results from the successful Pristine Inner Galaxy Survey (PIGS), a new survey looking for (and finding) the oldest stars in the bulge of the Milky Way. PIGS is using images with a specific color that is sensitive to the metallicity of stars, and can therefore efficiently select the metal-poor stars among millions of other, more metal-rich stars. The interesting candidates are followed up with spectroscopy, which is then analysed using two independent methods. With this strategy, PIGS has discovered the largest sample of metal-poor stars in the inner Galaxy to date. A new result from the PIGS data is that the metal-poor stars rotate more slowly around the Galactic center compared to the more metal-rich stars, and they show larger randomness in their motions as well. Another important contribution from PIGS is the discovery of tens of CEMP stars in the inner Galaxy, where previously only two such stars were known.
The new results from this thesis help us to understand the First Stars and the early history of the Milky Way. Ongoing and future large surveys will provide us with a lot of additional data in the coming years. It is an exciting time for the field of Galactic Archaeology.
T2 - Galaktische Archäologie mit den ältesten Sternen in der Milchstraße
KW - astrophysics
KW - stars
KW - Milky Way
KW - Galactic Archaeology
KW - Astrophysik
KW - Sterne
KW - Milchstraße
KW - Galaktische Archäologie
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-476022
ER -
TY - JOUR
A1 - Arnold, Patrick
T1 - Evolution of the mammalian neck from developmental, morpho-functional, and paleontological perspectives
JF - Journal of Mammalian Evolution
N2 - The mammalian neck adopts a variety of postures during daily life and generates numerous head trajectories. Despite its functional diversity, the neck is constrained to seven cervical vertebrae in (almost) all mammals. Given this low number, an unexpectedly high degree of modularity of the mammalian neck has more recently been uncovered. This work aims to review neck modularity in mammals from a developmental, morpho-functional, and paleontological perspective and how high functional diversity evolved in the mammalian neck after the occurrence of meristic limitations. The fixed number of cervical vertebrae and the developmental modularity of the mammalian neck are closely linked to anterior Hox genes expression and strong developmental integration between the neck and other body regions. In addition, basic neck biomechanics promote morpho-functional modularity due to preferred motion axes in the cranio-cervical and cervico-thoracic junction. These developmental and biomechanical determinants result in the characteristic and highly conserved shape variation among the vertebrae that delimits morphological modules. The step-wise acquisition of these unique cervical traits can be traced in the fossil record. The increasing functional specialization of neck modules, however, did not evolve all at once but started much earlier in the upper than in the lower neck. Overall, the strongly conserved modularity in the mammalian neck represents an evolutionary trade-off between the meristic constraints and functional diversity. Although a morpho-functional partition of the neck is common among amniotes, the degree of modularity and the way neck disparity is realized is unique in mammals.
KW - cervical spine
KW - modularity
KW - developmental constraints
KW - mammalian body
KW - plan
KW - neck evolution
Y1 - 2020
U6 - https://doi.org/10.1007/s10914-020-09506-9
SN - 1064-7554
SN - 1573-7055
VL - 28
IS - 2
SP - 173
EP - 183
PB - Springer
CY - New York
ER -
TY - GEN
A1 - Arnous, Ahmad
A1 - Zeckra, Martin
A1 - Venerdini, Agostina
A1 - Alvarado, Patricia
A1 - Arrowsmith, Ramón
A1 - Guillemoteau, Julien
A1 - Landgraf, Angela
A1 - Gutiérrez, Adolfo Antonio
A1 - Strecker, Manfred
T1 - Neotectonic Activity in the Low-Strain Broken Foreland (Santa Bárbara System) of the North-Western Argentinean Andes (26°S)
T2 - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe
N2 - Uplift in the broken Andean foreland of the Argentine Santa Bárbara System (SBS) is associated with the contractional reactivation of basement anisotropies, similar to those reported from the thick-skinned Cretaceous-Eocene Laramide province of North America. Fault scarps, deformed Quaternary deposits and landforms, disrupted drainage patterns, and medium-sized earthquakes within the SBS suggest that movement along these structures may be a recurring phenomenon, with yet to be defined repeat intervals and rupture lengths. In contrast to the Subandes thrust belt farther north, where eastward-migrating deformation has generated a well-defined thrust front, the SBS records spatiotemporally disparate deformation along structures that are only known to the first order. We present herein the results of geomorphic desktop analyses, structural field observations, and 2D electrical resistivity tomography and seismic-refraction tomography surveys and an interpretation of seismic reflection profiles across suspected fault scarps in the sedimentary basins adjacent to the Candelaria Range (CR) basement uplift, in the south-central part of the SBS. Our analysis in the CR piedmont areas reveals consistency between the results of near-surface electrical resistivity and seismic-refraction tomography surveys, the locations of prominent fault scarps, and structural geometries at greater depth imaged by seismic reflection data. We suggest that this deformation is driven by deep-seated blind thrusting beneath the CR and associated regional warping, while shortening involving Mesozoic and Cenozoic sedimentary strata in the adjacent basins was accommodated by layer-parallel folding and flexural-slip faults that cut through Quaternary landforms and deposits at the surface.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1008
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-480183
SN - 1866-8372
IS - 1008
SP - 1
EP - 25
ER -
TY - JOUR
A1 - Arnous, Ahmad
A1 - Zeckra, Martin
A1 - Venerdini, Agostina
A1 - Alvarado, Patricia
A1 - Arrowsmith, Ramón
A1 - Guillemoteau, Julien
A1 - Landgraf, Angela
A1 - Gutiérrez, Adolfo Antonio
A1 - Strecker, Manfred
T1 - Neotectonic Activity in the Low-Strain Broken Foreland (Santa Bárbara System) of the North-Western Argentinean Andes (26°S)
JF - Lithosphere
N2 - Uplift in the broken Andean foreland of the Argentine Santa Bárbara System (SBS) is associated with the contractional reactivation of basement anisotropies, similar to those reported from the thick-skinned Cretaceous-Eocene Laramide province of North America. Fault scarps, deformed Quaternary deposits and landforms, disrupted drainage patterns, and medium-sized earthquakes within the SBS suggest that movement along these structures may be a recurring phenomenon, with yet to be defined repeat intervals and rupture lengths. In contrast to the Subandes thrust belt farther north, where eastward-migrating deformation has generated a well-defined thrust front, the SBS records spatiotemporally disparate deformation along structures that are only known to the first order. We present herein the results of geomorphic desktop analyses, structural field observations, and 2D electrical resistivity tomography and seismic-refraction tomography surveys and an interpretation of seismic reflection profiles across suspected fault scarps in the sedimentary basins adjacent to the Candelaria Range (CR) basement uplift, in the south-central part of the SBS. Our analysis in the CR piedmont areas reveals consistency between the results of near-surface electrical resistivity and seismic-refraction tomography surveys, the locations of prominent fault scarps, and structural geometries at greater depth imaged by seismic reflection data. We suggest that this deformation is driven by deep-seated blind thrusting beneath the CR and associated regional warping, while shortening involving Mesozoic and Cenozoic sedimentary strata in the adjacent basins was accommodated by layer-parallel folding and flexural-slip faults that cut through Quaternary landforms and deposits at the surface.
Y1 - 2019
U6 - https://doi.org/10.2113/2020/8888588
SN - 1947-4253
SN - 1941-8264
VL - 2020
IS - 1
SP - 1
EP - 25
PB - GSA
CY - Boulder, Colo.
ER -
TY - THES
A1 - Arya, Pooja
T1 - Light controlled active and passive motion of colloidal particles
N2 - In this dissertation we introduce a concept of light driven active and passive manipulation of colloids trapped at solid/liquid interface. The motion is induced due to generation of light driven diffusioosmotic flow (LDDO) upon irradiation with light of appropriate wavelength. The origin of the flow is due to osmotic pressure gradient resulting from a concentration gradient at the solid/liquid interface of the photosensitive surfactant present in colloidal dispersion. The photosensitive surfactant consists of a cationic head group and a hydrophobic tail in which azobenzene group is integrated in. The azobenzene is known to undergo reversible photo-isomerization from a stable trans to a meta stable cis state under irradiation with UV light. Exposure to light of larger wavelength results in back photo-isomerization from cis to trans state. The two isomers have different molecular properties, for instance, trans isomer has a rod like structure and low polarity (0 dipole moment), whereas cis one is bent and has a dipole moment of ~3 Debye. Being integrated in the hydrophobic tail of the surfactant molecule, the azobenzene state determines the hydrophobicity of the whole molecule: in the trans state the surfactant is more hydrophobic than in the cis-state. In this way many properties of the surfactant such as the CMC, solubility and the interaction potential with a solid surface can be altered by light. When the solution containing such a surfactant is irradiated with focused light, a concentration gradient of different isomers is formed near the boundary of the irradiated area near the solid surface resulting in osmotic pressure gradient. The generated diffusioosmotic (DO) flow carries the particles passively along.
The local-LDDO flow can be generated around and by each particle when mesoporous silica colloids are dispersed in the surfactant solution. This is because porous particles act as a sink/source which absorbs azobenzene molecule in trans state and expels it when it is in the cis state. The DO flows generated at each particle interact resulting in aggregation or separation depending upon the initial state of surfactant molecules. The kinetic of aggregation and separation can be controlled and manipulated by altering the parameters such as the wavelength and intensity of the applied light, as well as surfactant and particle concentration. Using two wavelengths simultaneously allows for dynamic gathering and separation creating fascinating patterns such as 2D disk of well separated particles or establishing collective complex behaviour of particle ensemble as described in this thesis.
The mechanism of l-LDDO is also used to generate self-propelled motion. This is possible when half of the porous particle is covered by metal layer, basically blocking the pores on one side. The LDDO flow generated on uncapped side pushes the particle forward resulting in a super diffusive motion. The system of porous particle and azobenzene containing surfactant molecule can be utilized for various application such as drug delivery, cargo transportation, self-assembling, micro motors/ machines or micro patterning.
N2 - In dieser Doktorarbeit führen wir das Konzept der lichtinduzierten Diffusioosmose (LDDO) zur licht-kontrollierten passiven und aktiven Bewegung von Kolloiden an der fest-flüssig Grenzfläche ein. Bei diesem neuartigen Phänomen wird ein Grenzflächenfluss mittels Lichtes bestimmter Wellenlänge erzeugt. Ein lichtempfindliches Tensid wirkt hierbei als Quelle der Diffusioosmose: Durch Einstrahlung von Licht wird ein Konzentrationsgradient an der Oberfläche erzeugt, der wiederum ein Ungleichgewicht im lateralen osmotischen Druck verursacht. Dieser Druckunterschied führt dann zu einem grenzflächennahen diffusioosmotischen Fluss. Das lichtaktive Molekül besteht aus einer kationischen Kopfgruppe und einer hydrophoben Kohlenstoffkette, in die die Azobenzolgruppe eingebettet ist. Azobenzol fungiert hier als Lichtschalter, da es mit Licht zwischen einem stabilen trans und einem metastabilen cis Zustand hin- und hergeschaltet werden kann. Nahes UV Licht führt hier zur trans-cis und sichtbares Licht zur cis-trans Isomerisation. Das trans Isomer unterscheidet sich in einigen Eigenschaften vom cis Isomer. So ist z.B. das trans-Isomer langgestreckt und besitzt eine geringe Polarität (verschwindendes Dipolmoment), währenddessen das cis Isomer gebogen ist und ein deutliches Dipolmoment von ca. 3 Debye besitzt. Durch die Integration der Azobenzolgruppe in die hydrophobe Kette des Tensids, bestimmt der Isomerisationszustand des Tensids die Hydrophobizität des gesamten Moleküls: Der trans Zustand ist deutlich hydrophober als der cis Zustand. Dieser Unterschied zeigt sich in den Löslichkeitseigenschaften des Moleküls, der kritischen Mizellenkonzentration sowie des Wechselwirkungspotentials zwischen Molekül und Grenzfläche. Dies kann genutzt werden, um diese Eigenschaften mittels Lichtbestrahlung zu ändern. Wird das Molekül in Wasser gelöst und mit fokussiertem Licht bestrahlt, kann ein isomerer Konzentrationsgradient im Bestrahlungsbereich an der fest-flüssig Grenzfläche erzeugt werden, der wiederum in einem osmotischen Druckgunterschied resultiert. Die daraus resultierende Diffusioosmose (DO), welche an der Grenzfläche erzeugt wird, ist in der Lage Kolloide, die sich an der Grenzfläche befinden, transportieren (passiv).
Im Unterschied dazu kann ein sogenannter lokaler diffusioosmotischer Fluss (l-LDDO) um jedes einzelne Kolloid erzeugt werden, sobald es sich um meso-poröse Kolloide handelt. Hierbei agiert jedes Kolloid selbst als Konzentrationsquelle- bzw. –senke (ähnlich dem fokussiertem Licht im oberen Fall). Je nach Isomerisationszustand lagert sich das Molekül eher im Kolloid an oder bevorzugt die Umgebung des Wassers. Befindet sich das Molekül im trans Zustand lagert es sich im Kolloid an, während es im cis Zustand eher die Umgebung des Wassers sucht. Der diffusioosmotische Fluss wird um jedes einzelne Kolloid erzeugt, wodurch eine Wechselwirkung zwischen allen Kolloiden zustande kommt, die entweder anziehend oder abstoßend sein kann. Das hängt vom Isomerisationszustand der Tensidmoleküle vor der Bestrahlung ab. Durch die Änderung der folgenden Parameter kann die Bewegung der Kolloide kontrolliert werden: Lichtwellenlänge, Lichtintensität, Tensidkonzentration, Kolloidkonzentration. Durch die gleichzeitige Verwendung zweier verschiedener Lichtquellen (mit unterschiedlichen Wellenlängen), ist es möglich eine interessante Dynamik in der Anziehung und Abstoßung der Kolloide zu erzeugen, die faszinierende Kolloidformationen entstehen lassen wie sie in dieser Arbeit näher beschrieben werden.
Das Phänomen der lokalen Diffusioosmose kann auch zu selbst-getriebener Bewegung führen, nämlich wenn eine Hälfte des Kolloids bedeckt wird (z.B. mit einer Metallschicht) und somit für Tensidmoleküle undurchlässig macht. Der diffusioosmotische Fluss, der auf der unbedeckten Seite des Kolloids erzeugt wird, bewegt das Kolloid in eine Richtung fort und führt so durch Überlagerung zur thermischen Bewegung zu super-diffusivem Verhalten. Das System, bestehend aus porösen Kolloiden und azobenzolhaltigem Tensidmolekül kann sinnführend genutzt werden, z.B. für folgende Anwendungen: gezieltem Medikamententransport, Mikrofrachttransport, Selbstassemblierung, Mikromotoren/-maschinen oder Mikrostrukturierung.
T2 - Licht-kontrollierten passive und aktive Bewegung kolloidaler Partikel
KW - Azobenzene containing surfactant
KW - Photochemistry
KW - Porous silica particles
KW - Janus colloids
KW - LDDO
KW - diffusioosmotic flow
KW - Hydrophobic and hydrophillic interactions
KW - Kinetics of photoisomerization
KW - Azobenzol enthaltendes Tensid
KW - hydrophoben und hydrophile Wechselwirkungen
KW - Janus-Kolloid
KW - LDDO
KW - Photochemie
KW - poröse Siliciumdioxidpartikel
KW - diffusioosmotischer Fluss
KW - Isomerisierung Kinetik
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-483880
ER -
TY - JOUR
A1 - Arya, Pooja
A1 - Feldmann, David
A1 - Kopyshev, Alexey
A1 - Lomadze, Nino
A1 - Santer, Svetlana
T1 - Light driven guided and self-organized motion of mesoporous colloidal particles
JF - Soft matter
N2 - We report on guided and self-organized motion of ensembles of mesoporous colloidal particles that can undergo dynamic aggregation or separation upon exposure to light. The forces on particles involve the phenomenon of light-driven diffusioosmosis (LDDO) and are hydrodynamic in nature. They can be made to act passively on the ensemble as a whole but also used to establish a mutual interaction between particles. The latter scenario requires a porous colloid morphology such that the particle can act as a source or sink of a photosensitive surfactant, which drives the LDDO process. The interplay between the two modes of operation leads to fascinating possibilities of dynamical organization and manipulation of colloidal ensembles adsorbed at solid-liquid interfaces. While the passive mode can be thought of to allow for a coarse structuring of a cloud of colloids, the inter-particle mode may be used to impose a fine structure on a 2D particle grid. Local flow is used to impose and tailor interparticle interactions allowing for much larger interaction distances that can be achieved with, e.g., DLVO type of forces, and is much more versatile.
Y1 - 2019
U6 - https://doi.org/10.1039/c9sm02068c
SN - 1744-683X
SN - 1744-6848
VL - 16
IS - 5
SP - 1148
EP - 1155
PB - Royal Society of Chemistry
CY - Cambridge
ER -
TY - JOUR
A1 - Arya, Pooja
A1 - Jelken, Joachim
A1 - Feldmann, David
A1 - Lomadze, Nino
A1 - Santer, Svetlana
T1 - Light driven diffusioosmotic repulsion and attraction of colloidal particles
JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2 - In this paper, we introduce the phenomenon of light driven diffusioosmotic long-range attraction and repulsion of porous particles under irradiation with UV light. The change in the inter-particle interaction potential is governed by flow patterns generated around single colloids and results in reversible aggregation or separation of the mesoporous silica particles that are trapped at a solid surface. The range of the interaction potential extends to several times the diameter of the particle and can be adjusted by varying the light intensity. The "fuel" of the process is a photosensitive surfactant undergoing photo-isomerization from a more hydrophobic trans-state to a rather hydrophilic cis-state. The surfactant has different adsorption affinities to the particles depending on the isomerization state. The trans-isomer, for example, tends to accumulate in the negatively charged pores of the particles, while the cis-isomer prefers to remain in the solution. This implies that when under UV irradiation cis-isomers are being formed within the pores, they tend to diffuse out readily and generate an excess concentration near the colloid's outer surface, ultimately resulting in the initiation of diffusioosmotic flow. The direction of the flow depends strongly on the dynamic redistribution of the fraction of trans- and cis-isomers near the colloids due to different kinetics of photo-isomerization within the pores as compared to the bulk. The unique feature of the mechanism discussed in the paper is that the long-range mutual repulsion but also the attraction can be tuned by convenient external optical stimuli such as intensity so that a broad variety of experimental situations for manipulation of a particle ensemble can be realized.
Y1 - 2020
U6 - https://doi.org/10.1063/5.0007556
SN - 0021-9606
SN - 1089-7690
VL - 152
IS - 19
PB - American Institute of Physics
CY - Melville, NY
ER -
TY - JOUR
A1 - Arya, Pooja
A1 - Jelken, Joachim
A1 - Lomadze, Nino
A1 - Santer, Svetlana
A1 - Bekir, Marek
T1 - Kinetics of photo-isomerization of azobenzene containing surfactants
JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistry
N2 - We report on photoisomerization kinetics of azobenzene containing surfactants in aqueous solution. The surfactant molecule consists of a positively charged trimethylammonium bromide head group, a hydrophobic spacer connecting via 6 to 10 CH2 groups to the azobenzene unit, and the hydrophobic tail of 1 and 3CH(2) groups. Under exposure to light, the azobenzene photoisomerizes from more stable trans- to metastable cis-state, which can be switched back either thermally in dark or by illumination with light of a longer wavelength. The surfactant isomerization is described by a kinetic model of a pseudo first order reaction approaching equilibrium, where the intensity controls the rate of isomerization until the equilibrated state. The rate constants of the trans-cis and cis-trans photoisomerization are calculated as a function of several parameters such as wavelength and intensity of light, the surfactant concentration, and the length of the hydrophobic tail. The thermal relaxation rate from cis- to trans-state is studied as well. The surfactant isomerization shows a different kinetic below and above the critical micellar concentration of the trans isomer due to steric hindrance within the densely packed micelle but does not depend on the spacer length.
KW - genomic DNA conformation
KW - water-interface
KW - light photocontrol
KW - driven
KW - manipulation
KW - photoisomerization
KW - molecules
Y1 - 2020
U6 - https://doi.org/10.1063/1.5135913
SN - 0021-9606
SN - 1089-7690
VL - 152
IS - 2
PB - American Institute of Physics
CY - Melville
ER -