@misc{WolffBrandBaumgartenetal.2017, author = {Wolff, Wanja and Brand, Ralf and Baumgarten, Franz and L{\"o}sel, Johanna and Ziegler, Matthias}, title = {Modeling students' instrumental (mis-)use of substances to enhance cognitive performance}, issn = {1866-8364}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-401441}, pages = {11}, year = {2017}, abstract = {Background: Healthy university students have been shown to use psychoactive substances, expecting them to be functional means for enhancing their cognitive capacity, sometimes over and above an essentially proficient level. This behavior called Neuroenhancement (NE) has not yet been integrated into a behavioral theory that is able to predict performance. Job Demands Resources (JD-R) Theory for example assumes that strain (e.g. burnout) will occur and influence performance when job demands are high and job resources are limited at the same time. The aim of this study is to investigate whether or not university students' self-reported NE can be integrated into JD-R Theory's comprehensive approach to psychological health and performance. Methods: 1,007 students (23.56 ± 3.83 years old, 637 female) participated in an online survey. Lifestyle drug, prescription drug, and illicit substance NE together with the complete set of JD-R variables (demands, burnout, resources, motivation, and performance) were measured. Path models were used in order to test our data's fit to hypothesized main effects and interactions. Results: JD-R Theory could successfully be applied to describe the situation of university students. NE was mainly associated with the JD-R Theory's health impairment process: Lifestyle drug NE (p < .05) as well as prescription drug NE (p < .001) is associated with higher burnout scores, and lifestyle drug NE aggravates the study demands-burnout interaction. In addition, prescription drug NE mitigates the protective influence of resources on burnout and on motivation. Conclusion: According to our results, the uninformed trying of NE (i.e., without medical supervision) might result in strain. Increased strain is related to decreased performance. From a public health perspective, intervention strategies should address these costs of non-supervised NE. With regard to future research we propose to model NE as a means to reach an end (i.e. performance enhancement) rather than a target behavior itself. This is necessary to provide a deeper understanding of the behavioral roots and consequences of the phenomenon.}, language = {en} } @misc{WolffBrand2016, author = {Wolff, Wanja and Brand, Ralf}, title = {Editorial: using substances to enhance performance}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {443}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-407274}, pages = {2}, year = {2016}, language = {en} } @misc{WolffBrand2013, author = {Wolff, Wanja and Brand, Ralf}, title = {Subjective stressors in school and their relation to neuroenhancement}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-401131}, pages = {6}, year = {2013}, abstract = {Background: The use of psychoactive substances to neuroenhance cognitive performance is prevalent. Neuroenhancement (NE) in everyday life and doping in sport might rest on similar attitudinal representations, and both behaviors can be theoretically modeled by comparable means-to-end relations (substance-performance). A behavioral (not substance-based) definition of NE is proposed, with assumed functionality as its core component. It is empirically tested whether different NE variants (lifestyle drug, prescription drug, and illicit substance) can be regressed to school stressors. Findings: Participants were 519 students (25.8 +/- 8.4 years old, 73.1\% female). Logistic regressions indicate that a modified doping attitude scale can predict all three NE variants. Multiple NE substance abuse was frequent. Overwhelming demands in school were associated with lifestyle and prescription drug NE. Conclusions: Researchers should be sensitive for probable structural similarities between enhancement in everyday life and sport and systematically explore where findings from one domain can be adapted for the other. Policy makers should be aware that students might misperceive NE as an acceptable means of coping with stress in school, and help to form societal sensitivity for the topic of NE among our younger ones in general.}, language = {en} } @misc{WolffBaumgartenBrand2013, author = {Wolff, Wanja and Baumgarten, Franz and Brand, Ralf}, title = {Reduced self-control leads to disregard of an unfamiliar behavioral option}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-401386}, pages = {6}, year = {2013}, abstract = {Background: Neuroenhancement (NE), the use of psychoactive substances in order to enhance a healthy individual's cognitive functioning from a proficient to an even higher level, is prevalent in student populations. According to the strength model of self-control, people fail to self-regulate and fall back on their dominant behavioral response when finite self-control resources are depleted. An experiment was conducted to test the hypothesis that ego-depletion will prevent students who are unfamiliar with NE from trying it. Findings: 130 undergraduates, who denied having tried NE before (43\% female, mean age = 22.76 +/- 4.15 years old), were randomly assigned to either an ego-depletion or a control condition. The dependent variable was taking an "energy-stick" (a legal nutritional supplement, containing low doses of caffeine, taurine and vitamin B), offered as a potential means of enhancing performance on the bogus concentration task that followed. Logistic regression analysis showed that ego-depleted participants were three times less likely to take the substance, OR = 0.37, p = .01. Conclusion: This experiment found that trying NE for the first time was more likely if an individual's cognitive capacities were not depleted. This means that mental exhaustion is not predictive for NE in students for whom NE is not the dominant response. Trying NE for the first time is therefore more likely to occur as a thoughtful attempt at self-regulation than as an automatic behavioral response in stressful situations. We therefore recommend targeting interventions at this inter-individual difference. Students without previous reinforcing NE experience should be provided with information about the possible negative health outcomes of NE. Reconfiguring structural aspects in the academic environment (e.g. lessening workloads) might help to deter current users.}, language = {en} } @misc{WolffGastEversetal.2021, author = {Wolff, Martin and Gast, Klaus and Evers, Andreas and Kurz, Michael and Pfeiffer-Marek, Stefania and Sch{\"u}ler, Anja and Seckler, Robert and Thalhammer, Anja}, title = {A Conserved Hydrophobic Moiety and Helix-Helix Interactions Drive the Self-Assembly of the Incretin Analog Exendin-4}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {9}, issn = {1866-8372}, doi = {10.25932/publishup-52208}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-522081}, pages = {22}, year = {2021}, abstract = {Exendin-4 is a pharmaceutical peptide used in the control of insulin secretion. Structural information on exendin-4 and related peptides especially on the level of quaternary structure is scarce. We present the first published association equilibria of exendin-4 directly measured by static and dynamic light scattering. We show that exendin-4 oligomerization is pH dependent and that these oligomers are of low compactness. We relate our experimental results to a structural hypothesis to describe molecular details of exendin-4 oligomers. Discussion of the validity of this hypothesis is based on NMR, circular dichroism and fluorescence spectroscopy, and light scattering data on exendin-4 and a set of exendin-4 derived peptides. The essential forces driving oligomerization of exendin-4 are helix-helix interactions and interactions of a conserved hydrophobic moiety. Our structural hypothesis suggests that key interactions of exendin-4 monomers in the experimentally supported trimer take place between a defined helical segment and a hydrophobic triangle constituted by the Phe22 residues of the three monomeric subunits. Our data rationalize that Val19 might function as an anchor in the N-terminus of the interacting helix-region and that Trp25 is partially shielded in the oligomer by C-terminal amino acids of the same monomer. Our structural hypothesis suggests that the Trp25 residues do not interact with each other, but with C-terminal Pro residues of their own monomers.}, language = {en} } @misc{WolffCaprioglioStolterfohtetal.2019, author = {Wolff, Christian Michael and Caprioglio, Pietro and Stolterfoht, Martin and Neher, Dieter}, title = {Nonradiative recombination in perovskite solar cells}, series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, number = {772}, issn = {1866-8372}, doi = {10.25932/publishup-43762}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-437626}, pages = {20}, year = {2019}, abstract = {Perovskite solar cells combine high carrier mobilities with long carrier lifetimes and high radiative efficiencies. Despite this, full devices suffer from significant nonradiative recombination losses, limiting their VOC to values well below the Shockley-Queisser limit. Here, recent advances in understanding nonradiative recombination in perovskite solar cells from picoseconds to steady state are presented, with an emphasis on the interfaces between the perovskite absorber and the charge transport layers. Quantification of the quasi-Fermi level splitting in perovskite films with and without attached transport layers allows to identify the origin of nonradiative recombination, and to explain the VOC of operational devices. These measurements prove that in state-of-the-art solar cells, nonradiative recombination at the interfaces between the perovskite and the transport layers is more important than processes in the bulk or at grain boundaries. Optical pump-probe techniques give complementary access to the interfacial recombination pathways and provide quantitative information on transfer rates and recombination velocities. Promising optimization strategies are also highlighted, in particular in view of the role of energy level alignment and the importance of surface passivation. Recent record perovskite solar cells with low nonradiative losses are presented where interfacial recombination is effectively overcome—paving the way to the thermodynamic efficiency limit.}, language = {en} } @misc{WolfBleiss2005, author = {Wolf-Bleiß, Birgit}, title = {"Woher kommt eigentlich ...?" : Sprachberatung und Sprachgeschichte an der Universit{\"a}t Potsdam}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-9995}, year = {2005}, language = {de} } @misc{WolfHolzmeierWagneretal.2017, author = {Wolf, Thomas J. A. and Holzmeier, Fabian and Wagner, Isabella and Berrah, Nora and Bostedt, Christoph and Bozek, John and Bucksbaum, Philip H. and Coffee, Ryan and Cryan, James and Farrell, Joe and Feifel, Raimund and Martinez, Todd J. and McFarland, Brian and Mucke, Melanie and Nandi, Saikat and Tarantelli, Francesco and Fischer, Ingo and G{\"u}hr, Markus}, title = {Observing Femtosecond Fragmentation Using Ultrafast X-ray-Induced Auger Spectra}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-402692}, pages = {11}, year = {2017}, abstract = {Molecules often fragment after photoionization in the gas phase. Usually, this process can only be investigated spectroscopically as long as there exists electron correlation between the photofragments. Important parameters, like their kinetic energy after separation, cannot be investigated. We are reporting on a femtosecond time-resolved Auger electron spectroscopy study concerning the photofragmentation dynamics of thymine. We observe the appearance of clearly distinguishable signatures from thymine′s neutral photofragment isocyanic acid. Furthermore, we observe a time-dependent shift of its spectrum, which we can attribute to the influence of the charged fragment on the Auger electron. This allows us to map our time-dependent dataset onto the fragmentation coordinate. The time dependence of the shift supports efficient transformation of the excess energy gained from photoionization into kinetic energy of the fragments. Our method is broadly applicable to the investigation of photofragmentation processes.}, language = {en} } @misc{WolfSchuetzeJaeger2016, author = {Wolf, Sarah and Sch{\"u}tze, Franziska and Jaeger, Carlo}, title = {Balance or synergies between environment and economy}, series = {Postprints der Universit{\"a}t Potsdam : Wirtschafts- und Sozialwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Wirtschafts- und Sozialwissenschaftliche Reihe}, number = {126}, issn = {1867-5808}, doi = {10.25932/publishup-43699}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-436998}, pages = {13}, year = {2016}, abstract = {The UN sustainable development goals contain environmental, economic, and social objectives. They may only be reached, or at least it would be easier to reach them, if instead of a trade-off between these objectives that implies a need for balancing them, there are synergies to be reaped. This paper discusses how the structures of economic models typically used in policy analysis influence whether win-win strategies for the environment and the economy can be conceptualised and analysed. With a focus on climate policy modelling, the paper points out how, by construction, commonly used model structures find mitigation costs rather than benefits. This paper describes mechanisms that, when added to these model structures, can bring win- win options into a model's solution horizon, and which provide a spectrum of alternative modelling approaches that allow for the identification of such options.}, language = {en} } @misc{WojcinskiDupontSchmidtetal.2012, author = {Wojcinski, Sebastian and Dupont, Jennifer and Schmidt, Werner and Cassel, Michael and Hillemanns, Peter}, title = {Real-time ultrasound elastography in 180 axillary lymph nodes}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {626}, issn = {1866-8364}, doi = {10.25932/publishup-43158}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-431584}, pages = {12}, year = {2012}, abstract = {Background To determine the general appearance of normal axillary lymph nodes (LNs) in real-time tissue sonoelastography and to explore the method′s potential value in the prediction of LN metastases. Methods Axillary LNs in healthy probands (n=165) and metastatic LNs in breast cancer patients (n=15) were examined with palpation, B-mode ultrasound, Doppler and sonoelastography (assessment of the elasticity of the cortex and the medulla). The elasticity distributions were compared and sensitivity (SE) and specificity (SP) were calculated. In an exploratory analysis, positive and negative predictive values (PPV, NPV) were calculated based upon the estimated prevalence of LN metastases in different risk groups. Results In the elastogram, the LN cortex was significantly harder than the medulla in both healthy (p=0.004) and metastatic LNs (p=0.005). Comparing healthy and metastatic LNs, there was no difference in the elasticity distribution of the medulla (p=0.281), but we found a significantly harder cortex in metastatic LNs (p=0.006). The SE of clinical examination, B-mode ultrasound, Doppler ultrasound and sonoelastography was revealed to be 13.3\%, 40.0\%, 14.3\% and 60.0\%, respectively, and SP was 88.4\%, 96.8\%, 95.6\% and 79.6\%, respectively. The highest SE was achieved by the disjunctive combination of B-mode and elastographic features (cortex >3mm in B-mode or blue cortex in the elastogram, SE=73.3\%). The highest SP was achieved by the conjunctive combination of B-mode ultrasound and elastography (cortex >3mm in B-mode and blue cortex in the elastogram, SP=99.3\%). Conclusions Sonoelastography is a feasible method to visualize the elasticity distribution of LNs. Moreover, sonoelastography is capable of detecting elasticity differences between the cortex and medulla, and between metastatic and healthy LNs. Therefore, sonoelastography yields additional information about axillary LN status and can improve the PPV, although this method is still experimental.}, language = {en} } @misc{WojcikCeulemansGaedke2021, author = {Wojcik, Laurie Anne Myriam and Ceulemans, Ruben and Gaedke, Ursula}, title = {Functional diversity buffers the effects of a pulse perturbation on the dynamics of tritrophic food webs}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1251}, issn = {1866-8372}, doi = {10.25932/publishup-55373}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-553730}, pages = {25}, year = {2021}, abstract = {Biodiversity decline causes a loss of functional diversity, which threatens ecosystems through a dangerous feedback loop: This loss may hamper ecosystems' ability to buffer environmental changes, leading to further biodiversity losses. In this context, the increasing frequency of human-induced excessive loading of nutrients causes major problems in aquatic systems. Previous studies investigating how functional diversity influences the response of food webs to disturbances have mainly considered systems with at most two functionally diverse trophic levels. We investigated the effects of functional diversity on the robustness, that is, resistance, resilience, and elasticity, using a tritrophic—and thus more realistic—plankton food web model. We compared a non-adaptive food chain with no diversity within the individual trophic levels to a more diverse food web with three adaptive trophic levels. The species fitness differences were balanced through trade-offs between defense/growth rate for prey and selectivity/half-saturation constant for predators. We showed that the resistance, resilience, and elasticity of tritrophic food webs decreased with larger perturbation sizes and depended on the state of the system when the perturbation occurred. Importantly, we found that a more diverse food web was generally more resistant and resilient but its elasticity was context-dependent. Particularly, functional diversity reduced the probability of a regime shift toward a non-desirable alternative state. The basal-intermediate interaction consistently determined the robustness against a nutrient pulse despite the complex influence of the shape and type of the dynamical attractors. This relationship was strongly influenced by the diversity present and the third trophic level. Overall, using a food web model of realistic complexity, this study confirms the destructive potential of the positive feedback loop between biodiversity loss and robustness, by uncovering mechanisms leading to a decrease in resistance, resilience, and potentially elasticity as functional diversity declines.}, language = {en} } @misc{Woderich1997, author = {Woderich, Rudolf}, title = {Gelebte und inszenierte Identit{\"a}ten in Ostdeutschland}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-11288}, year = {1997}, abstract = {Germany gained its unity, but the restoration of virtual national cohesion presents itself as a lasting problem. The rebuilding of common national identity forms one complex aspect. Particular West and East German political, social and cultural features still exist. The East Germans brought elements of a peculiar identity into the unity; as a repercussion of some setbacks in their position and of some actual inter-German distinctions, their peculiarities are not yet in retreat. They prolong their role as conventional feelings, in temporary behaviours as an answer to their actual stance, and to a certain extent also with traits staged and suggested by entrenched media interpretations about the presently hampered inter-German evolution.}, language = {de} } @misc{WochatzSchraplauEngeletal.2022, author = {Wochatz, Monique and Schraplau, Anne and Engel, Tilman and Zecher, Mahli Megan and Sharon, Hadar and Alt, Yasmin and Mayer, Frank and Kalron, Alon}, title = {Application of eccentric training in various clinical populations}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {833}, issn = {1866-8364}, doi = {10.25932/publishup-58849}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-588493}, pages = {15}, year = {2022}, abstract = {Physical activity and exercise are effective approaches in prevention and therapy of multiple diseases. Although the specific characteristics of lengthening contractions have the potential to be beneficial in many clinical conditions, eccentric training is not commonly used in clinical populations with metabolic, orthopaedic, or neurologic conditions. The purpose of this pilot study is to investigate the feasibility, functional benefits, and systemic responses of an eccentric exercise program focused on the trunk and lower extremities in people with low back pain (LBP) and multiple sclerosis (MS). A six-week eccentric training program with three weekly sessions is performed by people with LBP and MS. The program consists of ten exercises addressing strength of the trunk and lower extremities. The study follows a four-group design (N = 12 per group) in two study centers (Israel and Germany): three groups perform the eccentric training program: A) control group (healthy, asymptomatic); B) people with LBP; C) people with MS; group D (people with MS) receives standard care physiotherapy. Baseline measurements are conducted before first training, post-measurement takes place after the last session both comprise blood sampling, self-reported questionnaires, mobility, balance, and strength testing. The feasibility of the eccentric training program will be evaluated using quantitative and qualitative measures related to the study process, compliance and adherence, safety, and overall program assessment. For preliminary assessment of potential intervention effects, surrogate parameters related to mobility, postural control, muscle strength and systemic effects are assessed. The presented study will add knowledge regarding safety, feasibility, and initial effects of eccentric training in people with orthopaedic and neurological conditions. The simple exercises, that are easily modifiable in complexity and intensity, are likely beneficial to other populations. Thus, multiple applications and implementation pathways for the herein presented training program are conceivable.}, language = {en} } @misc{WitzelNeugartRuppeletal.2015, author = {Witzel, Katja and Neugart, Susanne and Ruppel, Silke and Schreiner, Monika and Wiesner, Melanie and Baldermann, Susanne}, title = {Recent progress in the use of 'omics technologies in brassicaceous vegetables}, series = {Frontiers in plant science}, journal = {Frontiers in plant science}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-406479}, pages = {14}, year = {2015}, abstract = {Continuing advances in 'omics methodologies and instrumentation is enhancing the understanding of how plants cope with the dynamic nature of their growing environment. 'Omics platforms have been only recently extended to cover horticultural crop species. Many of the most widely cultivated vegetable crops belong to the genus Brassica: these include plants grown for their root (turnip, rutabaga/swede), their swollen stem base (kohlrabi), their leaves (cabbage, kale, pak choi) and their inflorescence (cauliflower, broccoli). Characterization at the genome, transcript, protein and metabolite levels has illustrated the complexity of the cellular response to a whole series of environmental stresses, including nutrient deficiency, pathogen attack, heavy metal toxicity, cold acclimation, and excessive and sub optimal irradiation. This review covers recent applications of omics technologies to the brassicaceous vegetables, and discusses future scenarios in achieving improvements in crop end-use quality.}, language = {en} } @misc{Wittmann2009, author = {Wittmann, Klaus}, title = {Die NATO als milit{\"a}rischer Akteur}, issn = {0944-8101}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-34189}, year = {2009}, abstract = {Die NATO gilt als das erfolgreichste Milit{\"a}rb{\"u}ndnis der Geschichte. Dabei war sie immer zugleich auch ein politisches B{\"u}ndnis. Notwendig ist die aktuelle Selbstvergewisserung zu Zweck und Hauptaufgaben. Verteidigung, Stabilisierung Europas und internationale Friedensmissionen werden dazu geh{\"o}ren. Wichtig bleibt ein gemeinsamer Wille zum praktischen Untersetzen durch verbesserte milit{\"a}rische F{\"a}higkeiten. Die Allianz sollte das spezifische milit{\"a}rische Instrument in die breiteren internationalen sicherheitsrelevanten Bem{\"u}hungen einbringen.}, language = {de} } @misc{WittSchaumloeffelSchaumloeffeletal.2020, author = {Witt, Barbara and Schauml{\"o}ffel, Dirk and Schauml{\"o}ffel, Dirk and Schwerdtle, Tanja}, title = {Subcellular Localization of Copper}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {862}, issn = {1866-8372}, doi = {10.25932/publishup-45954}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-459544}, pages = {27}, year = {2020}, abstract = {As an essential trace element, copper plays a pivotal role in physiological body functions. In fact, dysregulated copper homeostasis has been clearly linked to neurological disorders including Wilson and Alzheimer's disease. Such neurodegenerative diseases are associated with progressive loss of neurons and thus impaired brain functions. However, the underlying mechanisms are not fully understood. Characterization of the element species and their subcellular localization is of great importance to uncover cellular mechanisms. Recent research activities focus on the question of how copper contributes to the pathological findings. Cellular bioimaging of copper is an essential key to accomplish this objective. Besides information on the spatial distribution and chemical properties of copper, other essential trace elements can be localized in parallel. Highly sensitive and high spatial resolution techniques such as LA-ICP-MS, TEM-EDS, S-XRF and NanoSIMS are required for elemental mapping on subcellular level. This review summarizes state-of-the-art techniques in the field of bioimaging. Their strengths and limitations will be discussed with particular focus on potential applications for the elucidation of copper-related diseases. Based on such investigations, further information on cellular processes and mechanisms can be derived under physiological and pathological conditions. Bioimaging studies might enable the clarification of the role of copper in the context of neurodegenerative diseases and provide an important basis to develop therapeutic strategies for reduction or even prevention of copper-related disorders and their pathological consequences.}, language = {en} } @misc{WirthNeumannAntoniettietal.2014, author = {Wirth, Jonas and Neumann, Rainer and Antonietti, Markus and Saalfrank, Peter}, title = {Adsorption and photocatalytic splitting of water on graphitic carbon nitride}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-74391}, pages = {15917 -- 15926}, year = {2014}, abstract = {Graphitic carbon nitride, g-C₃N₄, is a promising organic photo-catalyst for a variety of redox reactions. In order to improve its efficiency in a systematic manner, however, a fundamental understanding of the microscopic interaction between catalyst, reactants and products is crucial. Here we present a systematic study of water adsorption on g-C₃N₄ by means of density functional theory and the density functional based tight-binding method as a prerequisite for understanding photocatalytic water splitting. We then analyze this prototypical redox reaction on the basis of a thermodynamic model providing an estimate of the overpotential for both water oxidation and H⁺ reduction. While the latter is found to occur readily upon irradiation with visible light, we derive a prohibitive overpotential of 1.56 eV for the water oxidation half reaction, comparing well with the experimental finding that in contrast to H₂ production O₂ evolution is only possible in the presence of oxidation cocatalysts.}, language = {en} } @misc{WirthKirschWlosczyketal.2016, author = {Wirth, Jonas and Kirsch, Harald and Wlosczyk, Sebastian and Tong, Yujin and Saalfrank, Peter and Kramer Campen, Richard}, title = {Characterization of water dissociation on α-Al2O3(1102)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-394497}, pages = {14822 -- 14832}, year = {2016}, abstract = {The interaction of water with α-alumina (i.e. α-Al2O3) surfaces is important in a variety of applications and a useful model for the interaction of water with environmentally abundant aluminosilicate phases. Despite its significance, studies of water interaction with α-Al2O3 surfaces other than the (0001) are extremely limited. Here we characterize the interaction of water (D2O) with a well defined α-Al2O3(1[1 with combining macron]02) surface in UHV both experimentally, using temperature programmed desorption and surface-specific vibrational spectroscopy, and theoretically, using periodic-slab density functional theory calculations. This combined approach makes it possible to demonstrate that water adsorption occurs only at a single well defined surface site (the so-called 1-4 configuration) and that at this site the barrier between the molecularly and dissociatively adsorbed forms is very low: 0.06 eV. A subset of OD stretch vibrations are parallel to this dissociation coordinate, and thus would be expected to be shifted to low frequencies relative to an uncoupled harmonic oscillator. To quantify this effect we solve the vibrational Schr{\"o}dinger equation along the dissociation coordinate and find fundamental frequencies red-shifted by more than 1500 cm-1. Within the context of this model, at moderate temperatures, we further find that some fraction of surface deuterons are likely delocalized: dissociatively and molecularly absorbed states are no longer distinguishable.}, language = {en} } @misc{WippertWiebking2018, author = {Wippert, Pia-Maria and Wiebking, Christine}, title = {Stress and Alterations in the Pain Matrix}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {438}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-412058}, pages = {11}, year = {2018}, abstract = {The genesis of chronic pain is explained by a biopsychosocial model. It hypothesizes an interdependency between environmental and genetic factors provoking aberrant long-term changes in biological and psychological regulatory systems. Physiological effects of psychological and physical stressors may play a crucial role in these maladaptive processes. Specifically, long-term demands on the stress response system may moderate central pain processing and influence descending serotonergic and noradrenergic signals from the brainstem, regulating nociceptive processing at the spinal level. However, the underlying mechanisms of this pathophysiological interplay still remain unclear. This paper aims to shed light on possible pathways between physical (exercise) and psychological stress and the potential neurobiological consequences in the genesis and treatment of chronic pain, highlighting evolving concepts and promising research directions in the treatment of chronic pain. Two treatment forms (exercise and mindfulness-based stress reduction as exemplary therapies), their interaction, and the dose-response will be discussed in more detail, which might pave the way to a better understanding of alterations in the pain matrix and help to develop future prevention and therapeutic concepts}, language = {en} } @misc{WippertRectorKuhnetal.2017, author = {Wippert, Pia-Maria and Rector, Michael V. and Kuhn, Gisela and Wuertz-Kozak, Karin}, title = {Stress and Alterations in Bones}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-395866}, pages = {7}, year = {2017}, abstract = {Decades of research have demonstrated that physical stress (PS) stimulates bone remodeling and affects bone structure and function through complex mechanotransduction mechanisms. Recent research has laid ground to the hypothesis that mental stress (MS) also influences bone biology, eventually leading to osteoporosis and increased bone fracture risk. These effects are likely exerted by modulation of hypothalamic-pituitary-adrenal axis activity, resulting in an altered release of growth hormones, glucocorticoids and cytokines, as demonstrated in human and animal studies. Furthermore, molecular cross talk between mental and PS is thought to exist, with either synergistic or preventative effects on bone disease progression depending on the characteristics of the applied stressor. This mini review will explain the emerging concept of MS as an important player in bone adaptation and its potential cross talk with PS by summarizing the current state of knowledge, highlighting newly evolving notions (such as intergenerational transmission of stress and its epigenetic modifications affecting bone) and proposing new research directions.}, language = {en} }