@article{AbeysekaraArchambaultArcheretal.2016, author = {Abeysekara, A. U. and Archambault, S. and Archer, A. and Benbow, W. and Bird, R. and Biteau, Jonathan and Buchovecky, M. and Buckley, J. H. and Bugaev, V. and Byrum, K. and Cardenzana, J. V. and Cerruti, M. and Chen, Xuhui and Christiansen, J. L. and Ciupik, L. and Connolly, M. P. and Cui, W. and Dickinson, H. J. and Dumm, J. and Eisch, J. D. and Errando, M. and Falcone, A. and Feng, Q. and Finley, J. P. and Fleischhack, H. and Flinders, A. and Fortin, P. and Fortson, L. and Furniss, A. and Gillanders, G. H. and Griffin, S. and Grube, J. and Gyuk, G. and Huetten, M. and Hanna, D. and Holder, J. and Humensky, T. B. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kelley-Hoskins, N. and Kertzman, M. and Kieda, D. and Krause, M. and Krennrich, F. and Lang, M. J. and Maier, G. and McArthur, S. and McCann, A. and Meagher, K. and Moriarty, P. and Mukherjee, R. and Nieto, D. and Ong, R. A. and Otte, A. N. and Park, N. and Pelassa, V. and Petrashyk, A. and Petry, D. and Pohl, Martin and Popkow, A. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Ratliff, G. and Reyes, L. C. and Reynolds, P. T. and Reynolds, K. and Richards, G. T. and Roache, E. and Rulten, C. and Santander, M. and Sembroski, G. H. and Shahinyan, K. and Smith, A. W. and Staszak, D. and Telezhinsky, Igor O. and Tucci, J. V. and Tyler, J. and Vincent, S. and Wakely, S. P. and Weiner, O. M. and Weinstein, A. and Wilhelm, Alina and Williams, D. A. and Zitzer, B.}, title = {VERITAS and multiwavelength observations of the BL Lacertae object 1ES 1741+196}, series = {Monthly notices of the Royal Astronomical Society}, volume = {459}, journal = {Monthly notices of the Royal Astronomical Society}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/stw664}, pages = {2550 -- 2557}, year = {2016}, abstract = {We present results from multiwavelength observations of the BL Lacertae object 1ES 1741 + 196, including results in the very high energy gamma-ray regime using the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The VERITAS time-averaged spectrum, measured above 180 GeV, is well modelled by a power law with a spectral index of 2.7 +/- 0.7(stat) +/- 0.2(syst). The integral flux above 180 GeV is (3.9 +/- 0.8(stat) +/- 1.0(syst)) x 10(-8) m(-2) s(-1), corresponding to 1.6 per cent of the Crab nebula flux on average. The multiwavelength spectral energy distribution of the source suggests that 1ES 1741+196 is an extreme-high-frequency-peaked BL Lacertae object. The observations analysed in this paper extend over a period of six years, during which time no strong flares were observed in any band. This analysis is therefore one of the few characterizations of a blazar in a non-flaring state.}, language = {en} } @misc{KneisAbonBronstertetal.2016, author = {Kneis, David and Abon, Catherine Cristobal and Bronstert, Axel and Heistermann, Maik}, title = {Verification of short-term runoff forecasts for a small Philippine basin (Marikina)}, series = {Hydrological sciences journal = Journal des sciences hydrologiques}, volume = {62}, journal = {Hydrological sciences journal = Journal des sciences hydrologiques}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0262-6667}, doi = {10.1080/02626667.2016.1183773}, pages = {205 -- 216}, year = {2016}, abstract = {Storm runoff from the Marikina River Basin frequently causes flood events in the Philippine capital region Metro Manila. This paper presents and evaluates a system to predict short-term runoff from the upper part of that basin (380km(2)). It was designed as a possible component of an operational warning system yet to be installed. For the purpose of forecast verification, hindcasts of streamflow were generated for a period of 15 months with a time-continuous, conceptual hydrological model. The latter was fed with real-time observations of rainfall. Both ground observations and weather radar data were tested as rainfall forcings. The radar-based precipitation estimates clearly outperformed the raingauge-based estimates in the hydrological verification. Nevertheless, the quality of the deterministic short-term runoff forecasts was found to be limited. For the radar-based predictions, the reduction of variance for lead times of 1, 2 and 3hours was 0.61, 0.62 and 0.54, respectively, with reference to a no-forecast scenario, i.e. persistence. The probability of detection for major increases in streamflow was typically less than 0.5. Given the significance of flood events in the Marikina Basin, more effort needs to be put into the reduction of forecast errors and the quantification of remaining uncertainties.}, language = {en} } @article{KlemmHerzschuhPestryakova2016, author = {Klemm, Juliane and Herzschuh, Ulrike and Pestryakova, Luidmila Agafyevna}, title = {Vegetation, climate and lake changes over the last 7000 years at the boreal treeline in north-central Siberia}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {147}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2015.08.015}, pages = {422 -- 434}, year = {2016}, language = {en} } @phdthesis{Niemeyer2016, author = {Niemeyer, Bastian}, title = {Vegetation reconstruction and assessment of plant diversity at the treeline ecotone in northern Siberia}, school = {Universit{\"a}t Potsdam}, pages = {146}, year = {2016}, language = {en} } @article{ZibulskiHerzschuhPestryakova2016, author = {Zibulski, Romy and Herzschuh, Ulrike and Pestryakova, Luidmila Agafyevna}, title = {Vegetation patterns along micro-relief and vegetation type transects in polygonal landscapes of the Siberian Arctic}, series = {Journal of vegetation science}, volume = {27}, journal = {Journal of vegetation science}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {1100-9233}, doi = {10.1111/jvs.12356}, pages = {377 -- 386}, year = {2016}, abstract = {QuestionHow important is the effect of micro-relief and vegetation type on the characteristics of vascular plants and bryophytes in low-centred polygons? LocationSiberian Arctic, Russia. MethodsEight low-centred polygons in northern Siberia were surveyed for vegetation along transects running from the rim to the pond via the rim-pond transition of each polygon and across a vegetation type gradient from open forest to tundra. ResultsThe cover of vascular plants and bryophytes displays no significant differences between the rim and rim-pond transition but is significantly lower in the pond section of the polygons. Alpha-diversity of vascular plants decreases strongly from rim to pond, whereas bryophyte diversity in pond plots is significantly distinct from the rim and the rim-pond transition. There is no clear trend in cover for either plant group along the vegetation type transect and only a weak trend in -diversity. However, both gradients are reflected in the compositional turnover. The applied indicator species analysis identified taxa characteristic of certain environmental conditions. Among others, we found vascular plants primarily characteristic of the rim and bryophyte taxa characteristic of each micro-relief level and vegetation type. ConclusionsThe observed gradual pattern in -diversity and composition of polygonal vegetation suggests that micro-relief is the main driver of changes in the vegetation composition, while vegetation type and the related forest cover change are of subordinate importance for polygonal vegetation patterns along the Siberian tree line.}, language = {en} } @article{CarusPaulSchroeder2016, author = {Carus, Jana and Paul, Maike and Schroeder, Boris}, title = {Vegetation as self-adaptive coastal protection: Reduction of current velocity and morphologic plasticity of a brackish marsh pioneer}, series = {Ecology and evolution}, volume = {6}, journal = {Ecology and evolution}, publisher = {Wiley}, address = {Hoboken}, issn = {2045-7758}, doi = {10.1002/ece3.1904}, pages = {1579 -- 1589}, year = {2016}, abstract = {By reducing current velocity, tidal marsh vegetation can diminish storm surges and storm waves. Conversely, currents often exert high mechanical stresses onto the plants and hence affect vegetation structure and plant characteristics. In our study, we aim at analysing this interaction from both angles. On the one hand, we quantify the reduction of current velocity by Bolboschoenus maritimus, and on the other hand, we identify functional traits of B. maritimus' ramets along environmental gradients. Our results show that tidal marsh vegetation is able to buffer a large proportion of the flow velocity at currents under normal conditions. Cross-shore current velocity decreased with distance from the marsh edge and was reduced by more than 50\% after 15 m of vegetation. We were furthermore able to show that plants growing at the marsh edge had a significantly larger diameter than plants from inside the vegetation. We found a positive correlation between plant thickness and cross-shore current which could provide an adaptive value in habitats with high mechanical stress. With the adapted morphology of plants growing at the highly exposed marsh edge, the entire vegetation belt is able to better resist the mechanical stress of high current velocities. This self-adaptive effect thus increases the ability of B. maritimus to grow and persist in the pioneer zone and may hence better contribute to ecosystem-based coastal protection by reducing current velocity.}, language = {en} } @unpublished{Alsaedy2016, author = {Alsaedy, Ammar}, title = {Variational primitive of a differential form}, volume = {5}, number = {4}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {2193-6943}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-89223}, pages = {8}, year = {2016}, abstract = {In this paper we specify the Dirichlet to Neumann operator related to the Cauchy problem for the gradient operator with data on a part of the boundary. To this end, we consider a nonlinear relaxation of this problem which is a mixed boundary problem of Zaremba type for the p-Laplace equation.}, language = {en} } @article{WolffSandouqaBrand2016, author = {Wolff, Wanja and Sandouqa, Yaser and Brand, Ralf}, title = {Using, the simple sample count to estimate the frequency of prescription drug neuroenhancement in a sample of Jordan employees}, series = {International journal of drug policy}, volume = {31}, journal = {International journal of drug policy}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0955-3959}, doi = {10.1016/j.drugpo.2015.12.014}, pages = {51 -- 55}, year = {2016}, abstract = {Background: Epidemiological research indicates that the use of prescription drugs to enhance cognitive functioning is prevalent in Western countries, however, research on this phenomenon in Arab countries is lacking. Our study aimed to investigate the frequency of neuroenhancement (NE) using prescription drugs in a sample of employees in Jordan. Methods: A sample of 1186 employees (37.11 +/- 8.37 years old, 495 female), of whom 723 (35.65 +/- 7.53 years old, 396 female) served as teachers, completed a paper-pencil questionnaire. The single sample count technique (SSC) was used in order to secure confidential, self-reporting of prescription drug NE. Results: The 12-month prevalence of NE, estimated with the SSC was 15.43\%. At 26.16\%, the prevalence estimate was markedly higher in the subsample of teachers compared to non-teachers, 0.29\%. Surprisingly, 336 participants did not use the SSC and directly affirmed or denied prescription drug NE. These direct responses yielded a prevalence of 11.57\% for the full sample, 9.73\% for the teachers and 15.60\% for the non-teachers. Conclusion: This is the first study of the frequency of NE in an Arab sample. Results indicate that the use of prescription drug NE is not limited to Western countries and that teachers in Jordan might constitute a high-risk population. Further, participants seem to differ in their use of indirect estimation methods for reporting prescription drug NE. For future research, it might be useful to triangulate standard self reports and indirect estimation methods to assess NE. Possible cultural differences and specific high-risk populations for NE should be investigated further. (C) 2015 Elsevier B.V. All rights reserved.}, language = {en} } @article{KretschmerCoumouDongesetal.2016, author = {Kretschmer, Marlene and Coumou, Dim and Donges, Jonathan and Runge, Jakob}, title = {Using Causal Effect Networks to Analyze Different Arctic Drivers of Midlatitude Winter Circulation}, series = {Journal of climate}, volume = {29}, journal = {Journal of climate}, publisher = {American Meteorological Soc.}, address = {Boston}, issn = {0894-8755}, doi = {10.1175/JCLI-D-15-0654.1}, pages = {4069 -- 4081}, year = {2016}, abstract = {In recent years, the Northern Hemisphere midlatitudes have suffered from severe winters like the extreme 2012/13 winter in the eastern United States. These cold spells were linked to a meandering upper-tropospheric jet stream pattern and a negative Arctic Oscillation index (AO). However, the nature of the drivers behind these circulation patterns remains controversial. Various studies have proposed different mechanisms related to changes in the Arctic, most of them related to a reduction in sea ice concentrations or increasing Eurasian snow cover. Here, a novel type of time series analysis, called causal effect networks (CEN), based on graphical models is introduced to assess causal relationships and their time delays between different processes. The effect of different Arctic actors on winter circulation on weekly to monthly time scales is studied, and robust network patterns are found. Barents and Kara sea ice concentrations are detected to be important external drivers of the midlatitude circulation, influencing winter AO via tropospheric mechanisms and through processes involving the stratosphere. Eurasia snow cover is also detected to have a causal effect on sea level pressure in Asia, but its exact role on AO remains unclear. The CEN approach presented in this study overcomes some difficulties in interpreting correlation analyses, complements model experiments for testing hypotheses involving teleconnections, and can be used to assess their validity. The findings confirm that sea ice concentrations in autumn in the Barents and Kara Seas are an important driver of winter circulation in the midlatitudes.}, language = {en} } @article{BrandKoch2016, author = {Brand, Ralf and Koch, Helen}, title = {Using Caffeine Pills for Performance Enhancement. An Experimental Study Neuroenhancements}, series = {Frontiers in psychology}, volume = {7}, journal = {Frontiers in psychology}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1664-1078}, doi = {10.3389/fpsyg.2016.00101}, pages = {11}, year = {2016}, abstract = {Recent research has indicated that university students sometimes use caffeine pills for neuroenhancement (NE; non-medical use of psychoactive substances or technology to produce a subjective enhancement in psychological functioning and experience), especially during exam preparation. In our factorial survey experiment, we manipulated the evidence participants were given about the prevalence of NE amongst peers and measured the resulting effects on the psychological predictors included in the Prototype-Willingness Model of risk behavior. Two hundred and thirty-one university students were randomized to a high prevalence condition (read faked research results overstating usage of caffeine pills amongst peers by a factor of 5; 50\%), low prevalence condition (half the estimated prevalence; 5\%) or control condition (no information about peer prevalence). Structural equation modeling confirmed that our participants' willingness and intention to use caffeine pills in the next exam period could be explained by their past use of neuroenhancers, attitude to NE and subjective norm about use of caffeine pills whilst image of the typical user was a much less important factor. Provision of inaccurate information about prevalence reduced the predictive power of attitude with respect to willingness by 40-45\%. This may be because receiving information about peer prevalence which does not fit with their perception of the social norm causes people to question their attitude. Prevalence information might exert a deterrent effect on NE via the attitude-willingness association. We argue that research into NE and deterrence of associated risk behaviors should be informed by psychological theory.}, language = {en} }