@article{WinklerAbel2016, author = {Winkler, Michael and Abel, Markus}, title = {Optimized setup for two-dimensional convection experiments in thin liquid films}, series = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques}, volume = {87}, journal = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques}, publisher = {American Institute of Physics}, address = {Melville}, issn = {0034-6748}, doi = {10.1063/1.4950871}, pages = {11}, year = {2016}, abstract = {We present a novel experimental setup to investigate two-dimensional thermal convection in a freestanding thin liquid film. Such films can be produced in a controlled way on the scale of 5-1000 nm. Our primary goal is to investigate convection patterns and the statistics of reversals in Rayleigh-Benard convection with varying aspect ratio. Additionally, questions regarding the physics of liquid films under controlled conditions can be investigated, like surface forces, or stability under varying thermodynamical parameters. The film is suspended in a frame which can be adjusted in height and width to span an aspect ratio range of Gamma = 0.16-10. The top and bottom frame elements can be set to specific temperature within T = 15 degrees C to 55 degrees C. A thickness to area ratio of approximately 108 enables only two-dimensional fluid motion in the time scales relevant for turbulent motion. The chemical composition of the film is well-defined and optimized for film stability and reproducibility and in combination with carefully controlled ambient parameters allows the comparison to existing experimental and numerical data. Published by AIP Publishing.}, language = {en} } @article{WenzLevermann2016, author = {Wenz, Leonie and Levermann, Anders}, title = {Enhanced economic connectivity to foster heat stress-related losses}, series = {Science Advances}, volume = {2}, journal = {Science Advances}, publisher = {American Assoc. for the Advancement of Science}, address = {Washington}, issn = {2375-2548}, doi = {10.1126/sciadv.1501026}, pages = {9}, year = {2016}, abstract = {Assessing global impacts of unexpected meteorological events in an increasingly connected world economy is important for estimating the costs of climate change. We show that since the beginning of the 21st century, the structural evolution of the global supply network has been such as to foster an increase of climate-related production losses. We compute first- and higher-order losses from heat stress-induced reductions in productivity under changing economic and climatic conditions between 1991 and 2011. Since 2001, the economic connectivity has augmented in such a way as to facilitate the cascading of production loss. The influence of this structural change has dominated over the effect of the comparably weak climate warming during this decade. Thus, particularly under future warming, the intensification of international trade has the potential to amplify climate losses if no adaptation measures are taken.}, language = {en} } @article{WenzKalkuhlSteckeletal.2016, author = {Wenz, Leonie and Kalkuhl, Matthias and Steckel, Jan Christoph and Creutzig, Felix}, title = {Teleconnected food supply shocks}, series = {Environmental research letters}, volume = {11}, journal = {Environmental research letters}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {1748-9326}, doi = {10.1088/1748-9326/11/3/035007}, pages = {10}, year = {2016}, abstract = {The 2008-2010 food crisis might have been a harbinger of fundamental climate-induced food crises with geopolitical implications. Heat-wave-induced yield losses in Russia and resulting export restrictions led to increases in market prices for wheat across the Middle East, likely contributing to the Arab Spring. With ongoing climate change, temperatures and temperature variability will rise, leading to higher uncertainty in yields for major nutritional crops. Here we investigate which countries are most vulnerable to teleconnected supply-shocks, i.e. where diets strongly rely on the import of wheat, maize, or rice, and where a large share of the population is living in poverty. We find that the Middle East is most sensitive to teleconnected supply shocks in wheat, Central America to supply shocks in maize, and Western Africa to supply shocks in rice. Weighing with poverty levels, Sub-Saharan Africa is most affected. Altogether, a simultaneous 10\% reduction in exports of wheat, rice, and maize would reduce caloric intake of 55 million people living in poverty by about 5\%. Export bans in major producing regions would put up to 200 million people below the poverty line at risk, 90\% of which live in Sub-Saharan Africa. Our results suggest that a region-specific combination of national increases in agricultural productivity and diversification of trade partners and diets can effectively decrease future food security risks.}, language = {en} } @phdthesis{Wenz2016, author = {Wenz, Leonie}, title = {Climate change impacts in an increasingly connected world}, school = {Universit{\"a}t Potsdam}, pages = {279}, year = {2016}, language = {en} } @article{WaldripNivenAbeletal.2016, author = {Waldrip, S. H. and Niven, R. K. and Abel, Markus and Schlegel, M.}, title = {Maximum Entropy Analysis of Hydraulic Pipe Flow Networks}, series = {Journal of hydraulic engineering}, volume = {142}, journal = {Journal of hydraulic engineering}, publisher = {American Society of Civil Engineers}, address = {Reston}, issn = {0733-9429}, doi = {10.1061/(ASCE)HY.1943-7900.0001126}, pages = {332 -- 347}, year = {2016}, language = {en} } @article{VlasovRosenblumPikovskij2016, author = {Vlasov, Vladimir and Rosenblum, Michael and Pikovskij, Arkadij}, title = {Dynamics of weakly inhomogeneous oscillator populations: perturbation theory on top of Watanabe-Strogatz integrability}, series = {Journal of physics : A, Mathematical and theoretical}, volume = {49}, journal = {Journal of physics : A, Mathematical and theoretical}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {1751-8113}, doi = {10.1088/1751-8113/49/31/31LT02}, pages = {8}, year = {2016}, abstract = {As has been shown by Watanabe and Strogatz (WS) (1993 Phys. Rev. Lett. 70 2391), a population of identical phase oscillators, sine-coupled to a common field, is a partially integrable system: for any ensemble size its dynamics reduce to equations for three collective variables. Here we develop a perturbation approach for weakly nonidentical ensembles. We calculate corrections to the WS dynamics for two types of perturbations: those due to a distribution of natural frequencies and of forcing terms, and those due to small white noise. We demonstrate that in both cases, the complex mean field for which the dynamical equations are written is close to the Kuramoto order parameter, up to the leading order in the perturbation. This supports the validity of the dynamical reduction suggested by Ott and Antonsen (2008 Chaos 18 037113) for weakly inhomogeneous populations.}, language = {en} } @article{VermaDenkerBoehmetal.2016, author = {Verma, Meetu and Denker, Carsten and B{\"o}hm, F. and Balthasar, H. and Fischer, C. E. and Kuckein, Christoph and Gonzalez, N. Bello and Berkefeld, T. and Collados Vera, M. and Diercke, Andrea and Feller, A. and Gonzalez Manrique, Sergio Javier and Hofmann, A. and Lagg, A. and Nicklas, H. and Orozco Suarez, D. and Pator Yabar, A. and Rezaei, R. and Schlichenmaier, R. and Schmidt, D. and Schmidt, W. and Sigwarth, M. and Sobotka, M. and Solanki, S. K. and Soltau, D. and Staude, J. and Strassmeier, Klaus G. and Volkmer, R. and von der L{\"u}he, O. and Waldmann, T.}, title = {Flow and magnetic field properties in the trailing sunspots of active region NOAA 12396}, series = {Astronomische Nachrichten = Astronomical notes}, volume = {337}, journal = {Astronomische Nachrichten = Astronomical notes}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0004-6337}, doi = {10.1002/asna.201612447}, pages = {1090 -- 1098}, year = {2016}, abstract = {Improved measurements of the photospheric and chromospheric three-dimensional magnetic and flow fields are crucial for a precise determination of the origin and evolution of active regions. We present an illustrative sample of multi-instrument data acquired during a two-week coordinated observing campaign in August 2015 involving, among others, the GREGOR solar telescope (imaging and near-infrared spectroscopy) and the space missions Solar Dynamics Observatory (SDO) and Interface Region Imaging Spectrograph (IRIS). The observations focused on the trailing part of active region NOAA 12396 with complex polarity inversion lines and strong intrusions of opposite polarity flux. The GREGOR Infrared Spectrograph (GRIS) provided Stokes IQUV spectral profiles in the photospheric Si i.1082.7 nm line, the chromospheric He I lambda 1083.0 nm triplet, and the photospheric Ca I lambda 1083.9 nm line. Carefully calibrated GRIS scans of the active region provided maps of Doppler velocity and magnetic field at different atmospheric heights. We compare quick-look maps with those obtained with the " Stokes Inversions based on Response functions" (SIR) code, which furnishes deeper insight into the magnetic properties of the region. We find supporting evidence that newly emerging flux and intruding opposite polarity flux are hampering the formation of penumbrae, i.e., a penumbra fully surrounding a sunspot is only expected after cessation of flux emergence in proximity to the sunspots. (C) 2016 WILEY-VCH Verlag GmbH\& Co.KGaA, Weinheim}, language = {en} } @article{VermaDenkerBalthasaretal.2016, author = {Verma, Meetu and Denker, Carsten and Balthasar, H. and Kuckein, Christoph and Gonz{\´a}lez Manrique, Sergio Javier and Sobotka, M. and Gonzalez, N. Bello and Hoch, S. and Diercke, Andrea and Kummerow, Philipp and Berkefeld, T. and Collados Vera, M. and Feller, A. and Hofmann, A. and Kneer, F. and Lagg, A. and L{\"o}hner-B{\"o}ttcher, J. and Nicklas, H. and Pastor Yabar, A. and Schlichenmaier, R. and Schmidt, D. and Schmidt, W. and Schubert, M. and Sigwarth, M. and Solanki, S. K. and Soltau, D. and Staude, J. and Strassmeier, Klaus G. and Volkmer, R. and von der L{\"u}he, O. and Waldmann, T.}, title = {Horizontal flow fields in and around a small active region The transition period between flux emergence and decay}, series = {Polymers}, volume = {596}, journal = {Polymers}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {1432-0746}, doi = {10.1051/0004-6361/201628380}, pages = {12}, year = {2016}, abstract = {Context. The solar magnetic field is responsible for all aspects of solar activity. Thus, emergence of magnetic flux at the surface is the first manifestation of the ensuing solar activity. Aims. Combining high-resolution and synoptic observations aims to provide a comprehensive description of flux emergence at photospheric level and of the growth process that eventually leads to a mature active region. Methods. The small active region NOAA 12118 emerged on 2014 July 17 and was observed one day later with the 1.5-m GREGOR solar telescope on 2014 July 18. High-resolution time-series of blue continuum and G-band images acquired in the blue imaging channel (BIC) of the GREGOR Fabry-Perot Interferometer (GFPI) were complemented by synoptic line-of-sight magnetograms and continuum images obtained with the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). Horizontal proper motions and horizontal plasma velocities were computed with local correlation tracking (LCT) and the differential affine velocity estimator (DAVE), respectively. Morphological image processing was employed to measure the photometric and magnetic area, magnetic flux, and the separation profile of the emerging flux region during its evolution. Results. The computed growth rates for photometric area, magnetic area, and magnetic flux are about twice as high as the respective decay rates. The space-time diagram using HMI magnetograms of five days provides a comprehensive view of growth and decay. It traces a leaf-like structure, which is determined by the initial separation of the two polarities, a rapid expansion phase, a time when the spread stalls, and a period when the region slowly shrinks again. The separation rate of 0.26 km s(-1) is highest in the initial stage, and it decreases when the separation comes to a halt. Horizontal plasma velocities computed at four evolutionary stages indicate a changing pattern of inflows. In LCT maps we find persistent flow patterns such as outward motions in the outer part of the two major pores, a diverging feature near the trailing pore marking the site of upwelling plasma and flux emergence, and low velocities in the interior of dark pores. We detected many elongated rapidly expanding granules between the two major polarities, with dimensions twice as large as the normal granules.}, language = {en} } @article{VelkUhligVikulinaetal.2016, author = {Velk, Natalia and Uhlig, Katja and Vikulina, Anna and Duschl, Claus and Volodkin, Dmitry}, title = {Mobility of lysozyme in poly(L-lysine)/hyaluronic acid multilayer films}, series = {Colloids and surfaces : an international journal devoted to fundamental and applied research on colloid and interfacial phenomena in relation to systems of biological origin ; B, Biointerfaces}, volume = {147}, journal = {Colloids and surfaces : an international journal devoted to fundamental and applied research on colloid and interfacial phenomena in relation to systems of biological origin ; B, Biointerfaces}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0927-7765}, doi = {10.1016/j.colsurfb.2016.07.055}, pages = {343 -- 350}, year = {2016}, abstract = {The spatial and temporal control over presentation of protein-based biomolecules such as growth factors and hormones is crucial for in vitro applications to mimic the complex in vivo environment. We investigated the interaction of a model protein lysozyme (Lys) with poly(L-lysine)/hyaluronic acid (PLL/HA) multilayer films. We focused on Lys diffusion as well as adsorption and retention within the film as a function of the film deposition conditions and post-treatment. Additionally, an effect of Lys concentration on its mobility was probed. A combination of confocal fluorescence microscopy, fluorescence recovery after photobleaching, and microfluidics was employed for this investigation. Our main finding is that adsorption of PLL and HA after protein loading induces acceleration and reduction of Lys mobility, respectively. These results suggest that a charge balance in the film to a high extent governs the protein-film interaction. We believe that control over protein mobility is a key to reach the full potential of the PLL/HA films as reservoirs for biomolecules depending on the application demand. (C) 2016 The Authors. Published by Elsevier B.V.}, language = {en} } @article{ValliappanArltDierckeetal.2016, author = {Valliappan, Senthamizh Pavai and Arlt, Rainer and Diercke, Andrea and Denker, Carsten and Vaquero, J. M.}, title = {Sunspot group tilt angle measurements from historical observations}, series = {Advances in space research}, volume = {58}, journal = {Advances in space research}, publisher = {Elsevier}, address = {Oxford}, issn = {0273-1177}, doi = {10.1016/j.asr.2016.03.002}, pages = {1468 -- 1474}, year = {2016}, abstract = {Sunspot positions from various historical sets of solar drawings are analyzed with respect to the tilt angles of bipolar sunspot groups. Data by Scheiner, Hevelius, Staudacher, Zucconi, Schwabe, and Sporer deliver a series of average tilt angles spanning a period of 270 years, additional to previously found values for 20th-century data obtained by other authors. We find that the average tilt angles before the Maunder minimum were not significantly different from the modem values. However, the average tilt angles of a period 50 years after the Maunder minimum, namely for cycles 0 and 1, were much lower and near zero. The normal tilt angles before the Maunder minimum suggest that it was not abnormally low tilt angles which drove the solar cycle into a grand minimum. (C) 2016 COSPAR. Published by Elsevier Ltd. All rights reserved.}, language = {en} }