TY - JOUR A1 - Yang, Jie A1 - Guehr, Markus A1 - Shen, Xiaozhe A1 - Li, Renkai A1 - Vecchione, Theodore A1 - Coffee, Ryan A1 - Corbett, Jeff A1 - Fry, Alan A1 - Hartmann, Nick A1 - Hast, Carsten A1 - Hegazy, Kareem A1 - Jobe, Keith A1 - Makasyuk, Igor A1 - Robinson, Joseph A1 - Robinson, Matthew Scott A1 - Vetter, Sharon A1 - Weathersby, Stephen A1 - Yoneda, Charles A1 - Wang, Xijie A1 - Centurion, Martin T1 - Diffractive Imaging of Coherent Nuclear Motion in Isolated Molecules JF - Physical review letters N2 - Observing the motion of the nuclear wave packets during a molecular reaction, in both space and time, is crucial for understanding and controlling the outcome of photoinduced chemical reactions. We have imaged the motion of a vibrational wave packet in isolated iodine molecules using ultrafast electron diffraction with relativistic electrons. The time-varying interatomic distance was measured with a precision 0.07 angstrom and temporal resolution of 230 fs full width at half maximum. The method is not only sensitive to the position but also the shape of the nuclear wave packet. Y1 - 2016 U6 - https://doi.org/10.1103/PhysRevLett.117.153002 SN - 0031-9007 SN - 1079-7114 VL - 117 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Hamaguchi, K. A1 - Oskinova, Lida A1 - Russell, C. M. P. A1 - Petre, R. A1 - Enoto, T. A1 - Morihana, K. A1 - Ishida, M. T1 - DISCOVERY OF RAPIDLY MOVING PARTIAL X-RAY ABSORBERS WITHIN GAMMA CASSIOPEIAE JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - detected six rapid X-ray spectral hardening events called "softness dips" in a similar to 100 ks observation in 2011. All the softness dip events show symmetric softness-ratio variations, and some of them have flat bottoms apparently due to saturation. The softness dip spectra are best described by either similar to 40% or similar to 70% partial covering absorption to kT similar to 12 keV plasma emission by matter with a neutral hydrogen column density of similar to(2-8) x 10(21) cm(-2), while the spectrum outside these dips is almost free of absorption. This result suggests the presence of two distinct X-ray-emitting spots in the.. Cas system, perhaps on a white dwarf (WD) companion with dipole mass accretion. The partial covering absorbers may be blobs in the Be stellar wind, the Be disk, or rotating around the WD companion. Weak correlations of the softness ratios to the hard X-ray flux suggest the presence of stable plasmas at kT similar to 0.9 and 5 keV, which may originate from the Be or WD winds. The formation of a Be star and WD binary system requires mass transfer between two stars; gamma Cas may have experienced such activity in the past. KW - blue stragglers KW - stars: emission-line, Be KW - stars: individual (gamma Cassiopeiae) KW - stars: winds, outflows KW - white dwarfs KW - X-rays: stars Y1 - 2016 U6 - https://doi.org/10.3847/0004-637X/832/2/140 SN - 0004-637X SN - 1538-4357 VL - 832 SP - 33 EP - 49 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Archambault, S. A1 - Archer, A. A1 - Barnacka, Anna A1 - Behera, B. A1 - Beilicke, M. A1 - Benbow, W. A1 - Berger, K. A1 - Bird, R. A1 - Böttcher, Markus A1 - Buckley, J. H. A1 - Bugaev, V. A1 - Cardenzana, J. V. A1 - Cerruti, M. A1 - Chen, Xuhui A1 - Christiansen, J. L. A1 - Ciupik, L. A1 - Collins-Hughes, E. A1 - Connolly, M. P. A1 - Cui, W. A1 - Dickinson, H. J. A1 - Dumm, J. A1 - Eisch, J. D. A1 - Errando, M. A1 - Falcone, A. A1 - Federici, Simone A1 - Feng, Q. A1 - Finley, J. P. A1 - Fleischhack, H. A1 - Fortson, L. A1 - Furniss, A. A1 - Gillanders, G. H. A1 - Godambe, S. A1 - Griffin, S. A1 - Griffiths, S. T. A1 - Grube, J. A1 - Gyuk, G. A1 - Hakansson, Nils A1 - Hanna, D. A1 - Holder, J. A1 - Hughes, G. A1 - Johnson, C. A. A1 - Kaaret, P. A1 - Kar, P. A1 - Kertzman, M. A1 - Khassen, Y. A1 - Kieda, D. A1 - Krawczynski, H. A1 - Kumar, S. A1 - Lang, M. J. A1 - Madhavan, A. S. A1 - Maier, G. A1 - McArthur, S. A1 - McCann, A. A1 - Meagher, K. A1 - Millis, J. A1 - Moriarty, P. A1 - Nelson, T. A1 - Nieto, D. A1 - Ong, R. A. A1 - Otte, A. N. A1 - Park, N. A1 - Perkins, J. S. A1 - Pohl, Martin A1 - Popkow, A. A1 - Prokoph, H. A1 - Pueschel, Elisa A1 - Quinn, J. A1 - Ragan, K. A1 - Rajotte, J. A1 - Reyes, L. C. A1 - Reynolds, P. T. A1 - Richards, G. T. A1 - Roache, E. A1 - Sembroski, G. H. A1 - Shahinyan, K. A1 - Smith, A. W. A1 - Staszak, D. A1 - Sweeney, K. A1 - Telezhinsky, Igor O. A1 - Tucci, J. V. A1 - Tyler, J. A1 - Varlotta, A. A1 - Vassiliev, V. V. A1 - Wakely, S. P. A1 - Welsing, R. A1 - Wilhelm, Alina A1 - Williams, D. A. A1 - Zitzer, B. T1 - Discovery of very high energy gamma rays from 1ES 1440+122 JF - Monthly notices of the Royal Astronomical Society KW - BL Lacertae objects: general KW - gamma-rays: general Y1 - 2016 U6 - https://doi.org/10.1093/mnras/stw1319 SN - 0035-8711 SN - 1365-2966 VL - 461 SP - 202 EP - 208 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Kurpiers, Jona A1 - Neher, Dieter T1 - Dispersive Non-Geminate Recombination in an Amorphous Polymer: Fullerene Blend JF - Scientific reports N2 - Recombination of free charge is a key process limiting the performance of solar cells. For low mobility materials, such as organic semiconductors, the kinetics of non-geminate recombination (NGR) is strongly linked to the motion of charges. As these materials possess significant disorder, thermalization of photogenerated carriers in the inhomogeneously broadened density of state distribution is an unavoidable process. Despite its general importance, knowledge about the kinetics of NGR in complete organic solar cells is rather limited. We employ time delayed collection field (TDCF) experiments to study the recombination of photogenerated charge in the high-performance polymer: fullerene blend PCDTBT:PCBM. NGR in the bulk of this amorphous blend is shown to be highly dispersive, with a continuous reduction of the recombination coefficient throughout the entire time scale, until all charge carriers have either been extracted or recombined. Rapid, contact-mediated recombination is identified as an additional loss channel, which, if not properly taken into account, would erroneously suggest a pronounced field dependence of charge generation. These findings are in stark contrast to the results of TDCF experiments on photovoltaic devices made from ordered blends, such as P3HT:PCBM, where non-dispersive recombination was proven to dominate the charge carrier dynamics under application relevant conditions. Y1 - 2016 U6 - https://doi.org/10.1038/srep26832 SN - 2045-2322 VL - 6 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Kurpiers, Jona A1 - Neher, Dieter T1 - Dispersive Non-Geminate Recombination in an Amorphous Polymer:Fullerene Blend JF - Scientific reports N2 - Recombination of free charge is a key process limiting the performance of solar cells. For low mobility materials, such as organic semiconductors, the kinetics of non-geminate recombination (NGR) is strongly linked to the motion of charges. As these materials possess significant disorder, thermalization of photogenerated carriers in the inhomogeneously broadened density of state distribution is an unavoidable process. Despite its general importance, knowledge about the kinetics of NGR in complete organic solar cells is rather limited. We employ time delayed collection field (TDCF) experiments to study the recombination of photogenerated charge in the high-performance polymer:fullerene blend PCDTBT:PCBM. NGR in the bulk of this amorphous blend is shown to be highly dispersive, with a continuous reduction of the recombination coefficient throughout the entire time scale, until all charge carriers have either been extracted or recombined. Rapid, contact-mediated recombination is identified as an additional loss channel, which, if not properly taken into account, would erroneously suggest a pronounced field dependence of charge generation. These findings are in stark contrast to the results of TDCF experiments on photovoltaic devices made from ordered blends, such as P3HT:PCBM, where non-dispersive recombination was proven to dominate the charge carrier dynamics under application relevant conditions. Y1 - 2016 U6 - https://doi.org/10.1038/srep26832 SN - 2045-2322 VL - 6 PB - Nature Publishing Group CY - London ER - TY - JOUR A1 - Lu, Guanghao A1 - Di Pietro, Riccardo A1 - Kölln, Lisa Sophie A1 - Nasrallah, Iyad A1 - Zhou, Ling A1 - Mollinger, Sonya A1 - Himmelberger, Scott A1 - Koch, Norbert A1 - Salleo, Alberto A1 - Neher, Dieter T1 - Dual-Characteristic Transistors Based on Semiconducting Polymer Blends JF - Advanced electronic materials N2 - A dual-characteristic polymer field-effect transistor has markedly different characteristics in low and high voltage operations. In the low-voltage range (<5 V) it shows sharp subthreshold slopes (0.3–0.4 V dec−1), using which a low-voltage inverter with gain 8 is realized, while high-voltage (>5 V) induces symmetric current with regard to drain and gate voltages, leading to discrete differential (trans) conductances. KW - charge accumulation KW - crystalline ordering KW - field-effect-transistor KW - semiconducting polymers Y1 - 2016 U6 - https://doi.org/10.1002/aelm.201600267 SN - 2199-160X VL - 2 SP - 2344 EP - 2351 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Guber, Christoph R. A1 - Richter, Philipp T1 - Dust depletion of Ca and Ti in QSO absorption-line systems JF - Wiley Interdisciplinary Reviews : Water N2 - Aims. To explore the role of titanium-and calcium-dust depletion in gas in and around galaxies, we systematically study Ti/Ca abundance ratios in intervening absorption-line systems at low and high redshift. Methods. We investigate high-resolution optical spectra obtained by the UVES instrument at the Very Large Telescope (VLT) and spectroscopically analyze 34 absorption-line systems at z <= 0.5 to measure column densities (or limits) for Ca II and Ti II. We complement our UVES data set with previously published absorption-line data on Ti/Ca for redshifts up to z similar to 3.8. Our absorber sample contains 110 absorbers including damped Lyman alpha systems (DLAs), sub-DLAs, and Lyman-Limit systems (LLS). We compare our Ti/Ca findings with results from the MilkyWay and the Magellanic Clouds and discuss the properties of Ti/Ca absorbers in the general context of quasar absorption-line systems. Results. Our analysis indicates that there are two distinct populations of absorbers with either high or low Ti/Ca ratios with a separation at [Ti/Ca] approximate to 1. While the calcium-dust depletion in most of the absorbers appears to be severe, the titanium depletions are mild in systems with high Ti/Ca ratios. The derived trend indicates that absorbers with high Ti/Ca ratios have dust-to-gas ratios that are substantially lower than in the Milky Way. We characterize the overall nature of the absorbers by correlating Ti/Ca with other observables (e.g., metallicity, velocity-component structure) and by modeling the ionization properties of singly-ionized Ca and Ti in different environments. Conclusions. We conclude that Ca II and Ti II bearing absorption-line systems trace predominantly neutral gas in the disks and inner halo regions of galaxies, where the abundance of Ca and Ti reflects the local metal and dust content of the gas. Our study suggests that the Ti/Ca ratio represents a useful measure for the gas-to-dust ratio and overall metallicity in intervening absorption-line systems. KW - quasars: absorption lines KW - dust, extinction KW - galaxies: abundances KW - galaxies: ISM KW - intergalactic medium Y1 - 2016 U6 - https://doi.org/10.1051/0004-6361/201628466 SN - 1432-0746 VL - 591 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Liu, Xiaodong A1 - Sachse, Manuel A1 - Spahn, Frank A1 - Schmidt, Jurgen T1 - Dynamics and distribution of Jovian dust ejected from the Galilean satellites JF - Journal of geophysical research, Planets N2 - In this paper, the dynamical analysis of the Jovian dust originating from the four Galilean moons is presented. High-accuracy orbital integrations of dust particles are used to determine their dynamical evolution. A variety of forces are taken into account, including the Lorentz force, solar radiation pressure, Poynting-Robertson drag, solar gravity, the satellites' gravity, plasma drag, and gravitational effects due to nonsphericity of Jupiter. More than 20,000 dust particles from each source moon in the size range from 0.05 μm to 1 cm are simulated over 8000 (Earth) years until each dust grain hits a sink (moons, Jupiter, or escape from the system). Configurations of dust number density in the Jovicentric equatorial inertial frame are calculated and shown. In a Jovicentric frame rotating with the Sun the dust distributions are found to be asymmetric. For certain small particle sizes, the dust population is displaced towards the Sun, while for certain larger sizes, the dust population is displaced away from the Sun. The average lifetime as a function of particle size for ejecta from each source moon is derived, and two sharp jumps in the average lifetime are analyzed. Transport of dust between the Galilean moons and to Jupiter is investigated. Most of the orbits for dust particles from Galilean moons are prograde, while, surprisingly, a small fraction of orbits are found to become retrograde mainly due to solar radiation pressure and Lorentz force. The distribution of orbital elements is also analyzed. Y1 - 2016 U6 - https://doi.org/10.1002/2016JE004999 SN - 2169-9097 SN - 2169-9100 VL - 121 SP - 1141 EP - 1173 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Vlasov, Vladimir A1 - Rosenblum, Michael A1 - Pikovskij, Arkadij T1 - Dynamics of weakly inhomogeneous oscillator populations: perturbation theory on top of Watanabe-Strogatz integrability JF - Journal of physics : A, Mathematical and theoretical N2 - 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. KW - Kuramoto model KW - oscillator populations KW - integrability KW - perturbation theory Y1 - 2016 U6 - https://doi.org/10.1088/1751-8113/49/31/31LT02 SN - 1751-8113 SN - 1751-8121 VL - 49 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Love, John A. A1 - Chou, Shu-Hua A1 - Huang, Ye A1 - Bazan, Guillermo C. A1 - Thuc-Quyen Nguyen, T1 - Effects of solvent additive on "s-shaped" curves in solution-processed small molecule solar cells JF - Beilstein journal of organic chemistry N2 - A novel molecular chromophore, p-SIDT(FBTThCA8)(2), is introduced as an electron-donor material for bulk heterojunction (BHJ) solar cells with broad absorption and near ideal energy levels for the use in combination with common acceptor materials. It is found that films cast from chlorobenzene yield devices with strongly s-shaped current-voltage curves, drastically limiting performance. We find that addition of the common solvent additive diiodooctane, in addition to facilitating crystallization, leads to improved vertical phase separation. This yields much better performing devices, with improved curve shape, demonstrating the importance of morphology control in BHJ devices and improving the understanding of the role of solvent additives. KW - current voltage analysis KW - morphology KW - organic solar cells Y1 - 2016 U6 - https://doi.org/10.3762/bjoc.12.249 SN - 1860-5397 VL - 12 SP - 2543 EP - 2555 PB - Beilstein-Institut zur Förderung der Chemischen Wissenschaften CY - Frankfurt, Main ER - TY - JOUR A1 - Ge, J. X. A1 - He, J. H. A1 - Yan, Huirong T1 - Effects of turbulent dust grain motion to interstellar chemistry JF - Monthly notices of the Royal Astronomical Society N2 - Theoretical studies have revealed that dust grains are usually moving fast through the turbulent interstellar gas, which could have significant effects upon interstellar chemistry by modifying grain accretion. This effect is investigated in this work on the basis of numerical gas-grain chemical modelling. Major features of the grain motion effect in the typical environment of dark clouds (DC) can be summarized as follows: (1) decrease of gas-phase (both neutral and ionic) abundances and increase of surface abundances by up to 2-3 orders of magnitude; (2) shifts of the existing chemical jumps to earlier evolution ages for gas-phase species and to later ages for surface species by factors of about 10; (3) a few exceptional cases in which some species turn out to be insensitive to this effect and some other species can show opposite behaviours too. These effects usually begin to emerge from a typical DC model age of about 10(5) yr. The grain motion in a typical cold neutral medium (CNM) can help overcome the Coulomb repulsive barrier to enable effective accretion of cations on to positively charged grains. As a result, the grain motion greatly enhances the abundances of some gas-phase and surface species by factors up to 2-6 or more orders of magnitude in the CNM model. The grain motion effect in a typical molecular cloud (MC) is intermediate between that of the DC and CNM models, but with weaker strength. The grain motion is found to be important to consider in chemical simulations of typical interstellar medium. KW - astrochemistry KW - turbulence KW - ISM: abundances KW - ISM: clouds KW - dust, extinction KW - ISM: molecules Y1 - 2016 U6 - https://doi.org/10.1093/mnras/stv2560 SN - 0035-8711 SN - 1365-2966 VL - 455 SP - 3570 EP - 3587 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Kumph, Muir A1 - Henkel, Carsten A1 - Rabl, Peter A1 - Brownnutt, Michael A1 - Blatt, Rainer T1 - Electric-field noise above a thin dielectric layer on metal electrodes JF - NEW JOURNAL OF PHYSICS N2 - The electric-field noise above a layered structure composed of a planar metal electrode covered by a thin dielectric is evaluated and it is found that the dielectric film considerably increases the noise level, in proportion to its thickness. Importantly, even a thin (mono) layer of a low-loss dielectric can enhance the noise level by several orders of magnitude compared to the noise above a bare metal. Close to this layered surface, the power spectral density of the electric field varies with the inverse fourth power of the distance to the surface, rather than with the inverse square, as it would above a bare metal surface. Furthermore, compared to a clean metal, where the noise spectrum does not vary with frequency (in the radio-wave and microwave bands), the dielectric layer can generate electricfield noise which scales in inverse proportion to the frequency. For various realistic scenarios, the noise levels predicted from this model are comparable to those observed in trapped-ion experiments. Thus, these findings are of particular importance for the understanding and mitigation of unwanted heating and decoherence in miniaturized ion traps. KW - ion trap KW - electric field noise KW - fluctuation dissipation Y1 - 2016 U6 - https://doi.org/10.1088/1367-2630/18/2/023020 SN - 1367-2630 VL - 18 SP - 1125 EP - 1136 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Zehbe, Rolf A1 - Mochales, Carolina A1 - Radzik, Daniela A1 - Mueller, Wolf-Dieter A1 - Fleck, Claudia T1 - Electrophoretic deposition of multilayered (cubic and tetragonal stabilized) zirconia ceramics for adapted crack deflection JF - Journal of the European Ceramic Society N2 - The electrophoretic deposition process was used to produce multi-layered ceramics consisting of alternating layers of fully stabilized cubic zirconia and partially stabilized tetragonal zirconia to make use of their different mechanical behaviour, investigating the possibility to deflect advancing cracks at the interfaces of the different layers. This crack deflection is apparently impacted by a toughening mechanism only found in the tetragonal stabilized zirconia polymorph and is characterized by the stress induced transformation of the metastable tetragonal phase into the monoclinic one, which is accompanied by a volume increase resulting in a closing mechanism for advancing cracks. While improving the electrophoretic deposition process, we investigated the transformation toughening mechanism at the layer interfaces and their effect on crack propagation. Investigations involved a combination of different imaging methods, including light microscopy, white light interferometry, atomic force microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and Raman spectroscopy. (C) 2015 Elsevier Ltd. All rights reserved. KW - Electrophoretic deposition KW - Yttria stabilized zirconia KW - Transformation toughening KW - Multilayer KW - Crack deflection Y1 - 2016 U6 - https://doi.org/10.1016/j.jeurceramsoc.2015.08.022 SN - 0955-2219 SN - 1873-619X VL - 36 SP - 357 EP - 364 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Romita, Krista A1 - Lada, Elizabeth A1 - Cioni, Maria-Rosa L. T1 - EMBEDDED CLUSTERS IN THE LARGE MAGELLANIC CLOUD USING THE VISTA MAGELLANIC CLOUDS SURVEY JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - We present initial results of the first large-scale survey of embedded star clusters in molecular clouds in the Large Magellanic Cloud (LMC) using near-infrared imaging from the Visible and Infrared Survey Telescope for Astronomy Magellanic Clouds Survey. We explored a ~1.65 deg2 area of the LMC, which contains the well-known star-forming region 30 Doradus as well as ~14% of the galaxy's CO clouds, and identified 67 embedded cluster candidates, 45 of which are newly discovered as clusters. We have determined the sizes, luminosities, and masses for these embedded clusters, examined the star formation rates (SFRs) of their corresponding molecular clouds, and made a comparison between the LMC and the Milky Way. Our preliminary results indicate that embedded clusters in the LMC are generally larger, more luminous, and more massive than those in the local Milky Way. We also find that the surface densities of both embedded clusters and molecular clouds is ~3 times higher than in our local environment, the embedded cluster mass surface density is ~40 times higher, the SFR is ~20 times higher, and the star formation efficiency is ~10 times higher. Despite these differences, the SFRs of the LMC molecular clouds are consistent with the SFR scaling law presented in Lada et al. This consistency indicates that while the conditions of embedded cluster formation may vary between environments, the overall process within molecular clouds may be universal. KW - galaxies: star clusters: general KW - Magellanic Clouds KW - stars: formation Y1 - 2016 U6 - https://doi.org/10.3847/0004-637X/821/1/51 SN - 0004-637X SN - 1538-4357 VL - 821 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Wenz, Leonie A1 - Levermann, Anders T1 - Enhanced economic connectivity to foster heat stress-related losses JF - Science Advances N2 - 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. Y1 - 2016 U6 - https://doi.org/10.1126/sciadv.1501026 SN - 2375-2548 VL - 2 PB - American Assoc. for the Advancement of Science CY - Washington ER - TY - JOUR A1 - Nishikawa, Ken-Ichi A1 - Frederiksen, J. T. A1 - Nordlund, A. A1 - Mizuno, Y. A1 - Hardee, P. E. A1 - Niemiec, J. A1 - Gomez, J. L. A1 - Dutan, I. A1 - Meli, A. A1 - Sol, H. A1 - Pohl, Martin A1 - Hartmann, D. H. T1 - EVOLUTION OF GLOBAL RELATIVISTIC JETS: COLLIMATIONS AND EXPANSION WITH kKHI AND THE WEIBEL INSTABILITY JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - In the study of relativistic jets one of the key open questions is their interaction with the environment. Here. we study the initial evolution of both electron-proton (e(-) - p(+)) and electron-positron (e(+/-)) relativistic jets, focusing on their lateral interaction with ambient plasma. We follow the evolution of toroidal magnetic fields generated by both the kinetic Kelvin-Helmholtz and Mushroom instabilities. For an e(-) - p(+) jet, the induced magnetic field collimates the jet and electrons are perpendicularly accelerated. As the instabilities saturate and subsequently weaken, the magnetic polarity switches from clockwise to counterclockwise in the middle of the jet. For an e(+/-) jet, we find strong mixing of electrons and positrons with the ambient plasma, resulting in the creation of a bow shock. The merging of current filaments generates density inhomogeneities that. initiate a forward shock. Strong jet-ambient plasma mixing prevents a full development of the jet (on the scale studied), revealing evidence for both jet collimation and particle acceleration in the forming bow shock. Differences in the magnetic field structure generated by e(-) - p(+) and e(+/-) jets may contribute to the polarization properties of the observed emission in AGN jets and gamma-ray bursts. KW - acceleration of particles KW - plasmas KW - radiation mechanisms: non-thermal KW - relativistic processes KW - stars: jets KW - Sun: magnetic fields Y1 - 2016 U6 - https://doi.org/10.3847/0004-637X/820/2/94 SN - 0004-637X SN - 1538-4357 VL - 820 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Archambault, S. A1 - Archer, A. A1 - Aune, T. A1 - Barnacka, Anna A1 - Benbow, W. A1 - Bird, R. A1 - Buchovecky, M. A1 - Buckley, J. H. A1 - Bugaev, V. A1 - Byrum, K. A1 - Cardenzana, J. V. A1 - Cerruti, M. A1 - Chen, Xuhui A1 - Ciupik, L. A1 - Collins-Hughes, E. A1 - Connolly, M. P. A1 - Cui, W. A1 - Dickinson, H. J. A1 - Dumm, J. A1 - Eisch, J. D. A1 - Falcone, A. A1 - Feng, Q. A1 - Finley, J. P. A1 - Fleischhack, H. A1 - Flinders, A. A1 - Fortin, P. A1 - Fortson, L. A1 - Furniss, A. A1 - Gillanders, G. H. A1 - Griffin, S. A1 - Grube, J. A1 - Gyuk, G. A1 - Huetten, M. A1 - Hakansson, Nils A1 - Hanna, D. A1 - Holder, J. A1 - Humensky, T. B. A1 - Johnson, C. A. A1 - Kaaret, P. A1 - Kar, P. A1 - Kelley-Hoskins, N. A1 - Kertzman, M. A1 - Khassen, Y. A1 - Kieda, D. A1 - Krause, M. A1 - Krennrich, F. A1 - Kumar, S. A1 - Lang, M. J. A1 - Maier, G. A1 - McArthur, S. A1 - McCann, A. A1 - Meagher, K. A1 - Millis, J. A1 - Moriarty, P. A1 - Mukherjee, R. A1 - Nieto, D. A1 - Ong, R. A. A1 - Otte, A. N. A1 - Pandel, D. A1 - Park, N. A1 - Pelassa, V. A1 - Pohl, Martin A1 - Popkow, A. A1 - Pueschel, Elisa A1 - Quinn, J. A1 - Ragan, K. A1 - Reynolds, P. T. A1 - Richards, G. T. A1 - Roache, E. A1 - Rousselle, J. A1 - Rulten, C. A1 - Santander, M. A1 - Sembroski, G. H. A1 - Shahinyan, K. A1 - Smith, A. W. A1 - Staszak, D. A1 - Telezhinsky, Igor O. A1 - Tucci, J. V. A1 - Tyler, J. A1 - Vincent, S. A1 - Wakely, S. P. A1 - Weiner, O. M. A1 - Weinstein, A. A1 - Wilhelm, Alina A1 - Williams, D. A. A1 - Zitzer, B. T1 - EXCEPTIONALLY BRIGHT TEV FLARES FROM THE BINARY LS I+61 degrees 303 JF - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters N2 - The TeV binary system LS I +61 degrees 303 is known for its regular, non-thermal emission pattern that traces the orbital period of the compact object in its 26.5 day orbit around its B0 Ve star companion. The system typically presents elevated TeV emission around apastron passage with flux levels between 5% and 15% of the steady flux from the Crab Nebula (> 300 GeV). In this article, VERITAS observations of LS I + 61 degrees. 303 taken in late 2014 are presented, during which bright TeV flares around apastron at flux levels peaking above 30% of the Crab Nebula flux were detected. This is the brightest such activity from this source ever seen in the TeV regime. The strong outbursts have rise and fall times of less than a day. The short timescale of the flares, in conjunction with the observation of 10 TeV photons from LS I + 61 degrees 303 during the flares, provides constraints on the properties of the accelerator in the source. KW - binaries: general KW - gamma-rays: general KW - stars: individual (LS I+61 degrees 303, VER J0240+612) KW - X-rays: binaries Y1 - 2016 U6 - https://doi.org/10.3847/2041-8205/817/1/L7 SN - 2041-8205 SN - 2041-8213 VL - 817 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Wisotzki, Lutz A1 - Bacon, Roland A1 - Blaizot, J. A1 - Brinchmann, Jarle A1 - Herenz, Edmund Christian A1 - Schaye, Joop A1 - Bouche, Nicolas A1 - Cantalupo, Sebastiano A1 - Contini, Thierry A1 - Carollo, C. M. A1 - Caruana, Joseph A1 - Courbot, J. -B. A1 - Emsellem, E. A1 - Kamann, S. A1 - Kerutt, Josephine Victoria A1 - Leclercq, F. A1 - Lilly, S. J. A1 - Patricio, V. A1 - Sandin, C. A1 - Steinmetz, Matthias A1 - Straka, Lorrie A. A1 - Urrutia, Tanya A1 - Verhamme, A. A1 - Weilbacher, Peter Michael A1 - Wendt, Martin T1 - Extended Lyman alpha haloes around individual high-redshift galaxies revealed by MUSE JF - Science N2 - We report the detection of extended Ly alpha emission around individual star-forming galaxies at redshifts z = 3-6 in an ultradeep exposure of the Hubble Deep Field South obtained with MUSE on the ESO-VLT. The data reach a limiting surface brightness (1 sigma) of similar to 1 x 10(-19) erg s(-1) cm(-2) arcsec(-2) in azimuthally averaged radial profiles, an order of magnitude improvement over previous narrowband imaging. Our sample consists of 26 spectroscopically confirmed Ly alpha-emitting, but mostly continuum-faint (m(AB) greater than or similar to 27) galaxies. In most objects the Ly alpha emission is considerably more extended than the UV continuum light. While five of the faintest galaxies in the sample show no significantly detected Ly alpha haloes, the derived upper limits suggest that this is due to insufficient S/N. Ly alpha haloes therefore appear to be ubiquitous even for low-mass (similar to 10(8)-10(9) M-circle dot) star-forming galaxies at z > 3. We decompose the Ly alpha emission of each object into a compact component tracing the UV continuum and an extended halo component, and infer sizes and luminosities of the haloes. The extended Ly alpha emission approximately follows an exponential surface brightness distribution with a scale length of a few kpc. While these haloes are thus quite modest in terms of their absolute sizes, they are larger by a factor of 5-15 than the corresponding rest-frame UV continuum sources as seen by HST. They are also much more extended, by a factor similar to 5, than Ly alpha haloes around low-redshift star-forming galaxies. Between similar to 40% and greater than or similar to 90% of the observed Ly alpha flux comes from the extended halo component, with no obvious correlation of this fraction with either the absolute or the relative size of the Ly alpha halo. Our observations provide direct insights into the spatial distribution of at least partly neutral gas residing in the circumgalactic medium of low to intermediate mass galaxies at z > 3. KW - galaxies: high-redshift KW - galaxies: evolution KW - galaxies: formation KW - cosmology: observations KW - intergalactic medium Y1 - 2016 U6 - https://doi.org/10.1051/0004-6361/201527384 SN - 1432-0746 VL - 587 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Intravaia, F. A1 - Behunin, R. O. A1 - Henkel, Carsten A1 - Busch, K. A1 - Dalvit, D. A. R. T1 - Failure of Local Thermal Equilibrium in Quantum Friction JF - Physical review letters N2 - Recent progress in manipulating atomic and condensed matter systems has instigated a surge of interest in nonequilibrium physics, including many-body dynamics of trapped ultracold atoms and ions, near-field radiative heat transfer, and quantum friction. Under most circumstances the complexity of such nonequilibrium systems requires a number of approximations to make theoretical descriptions tractable. In particular, it is often assumed that spatially separated components of a system thermalize with their immediate surroundings, although the global state of the system is out of equilibrium. This powerful assumption reduces the complexity of nonequilibrium systems to the local application of well-founded equilibrium concepts. While this technique appears to be consistent for the description of some phenomena, we show that it fails for quantum friction by underestimating by approximately 80% the magnitude of the drag force. Our results show that the correlations among the components of driven, but steady-state, quantum systems invalidate the assumption of local thermal equilibrium, calling for a critical reexamination of this approach for describing the physics of nonequilibrium systems. Y1 - 2016 U6 - https://doi.org/10.1103/PhysRevLett.117.100402 SN - 0031-9007 SN - 1079-7114 VL - 117 SP - 989 EP - 1010 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Kim, Kyung-Chan A1 - Shprits, Yuri Y. A1 - Blake, J. Bernard T1 - Fast injection of the relativistic electrons into the inner zone and the formation of the split-zone structure during the Bastille Day storm in July 2000 JF - Journal of geophysical research : Space physics N2 - During the July 2000 geomagnetic storm, known as the Bastille Day storm, Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX)/Heavy Ion Large Telescope (HILT) observed a strong injection of similar to 1MeV electrons into the slot region (L similar to 2.5) during the storm main phase. Then, during the following month, electrons were clearly seen diffusing inward down to L=2 and forming a pronounced split structure encompassing a narrow, newly formed slot region around L=3. SAMPEX observations are first compared with electron and proton observations on HEO-3 and NOAA-15 to validate that the observed unusual dynamics was not caused by proton contamination of the SAMPEX instrument. The time-dependent 3-D Versatile Electron Radiation Belt (VERB) simulation of 1MeV electron flux evolution is compared with the SAMPEX/HILT observations. The results show that the VERB code predicts overall time evolution of the observed split structure. The simulated split structure is produced by pitch angle scattering into the Earth atmosphere of similar to 1MeV electrons by plasmaspheric hiss. KW - inner radiation zone and slot region KW - Bastille Day geomagnetic storm KW - 3-D diffusion simulation KW - plasmaspheric hiss Y1 - 2016 U6 - https://doi.org/10.1002/2015JA022072 SN - 2169-9380 SN - 2169-9402 VL - 121 SP - 8329 EP - 8342 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Yang, Jie A1 - Gühr, Markus A1 - Vecchione, Theodore A1 - Robinson, Matthew Scott A1 - Li, Renkai A1 - Hartmann, Nick A1 - Shen, Xiaozhe A1 - Coffee, Ryan A1 - Corbett, Jeff A1 - Fry, Alan A1 - Gaffney, Kelly A1 - Gorkhover, Tais A1 - Hast, Carsten A1 - Jobe, Keith A1 - Makasyuk, Igor A1 - Reid, Alexander A1 - Robinson, Joseph A1 - Vetter, Sharon A1 - Wang, Fenglin A1 - Weathersby, Stephen A1 - Yoneda, Charles A1 - Wang, Xijie A1 - Centurion, Martin T1 - Femtosecond gas phase electron diffraction with MeV electrons JF - Faraday discussions N2 - We present results on ultrafast gas electron diffraction (UGED) experiments with femtosecond resolution using the MeV electron gun at SLAC National Accelerator Laboratory. UGED is a promising method to investigate molecular dynamics in the gas phase because electron pulses can probe the structure with a high spatial resolution. Until recently, however, it was not possible for UGED to reach the relevant timescale for the motion of the nuclei during a molecular reaction. Using MeV electron pulses has allowed us to overcome the main challenges in reaching femtosecond resolution, namely delivering short electron pulses on a gas target, overcoming the effect of velocity mismatch between pump laser pulses and the probe electron pulses, and maintaining a low timing jitter. At electron kinetic energies above 3 MeV, the velocity mismatch between laser and electron pulses becomes negligible. The relativistic electrons are also less susceptible to temporal broadening due to the Coulomb force. One of the challenges of diffraction with relativistic electrons is that the small de Broglie wavelength results in very small diffraction angles. In this paper we describe the new setup and its characterization, including capturing static diffraction patterns of molecules in the gas phase, finding time-zero with sub-picosecond accuracy and first time-resolved diffraction experiments. The new device can achieve a temporal resolution of 100 fs root-mean-square, and sub-angstrom spatial resolution. The collimation of the beam is sufficient to measure the diffraction pattern, and the transverse coherence is on the order of 2 nm. Currently, the temporal resolution is limited both by the pulse duration of the electron pulse on target and by the timing jitter, while the spatial resolution is limited by the average electron beam current and the signal-to-noise ratio of the detection system. We also discuss plans for improving both the temporal resolution and the spatial resolution. Y1 - 2016 U6 - https://doi.org/10.1039/c6fd00071a SN - 1359-6640 SN - 1364-5498 VL - 194 SP - 563 EP - 581 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Godec, Aljaz A1 - Metzler, Ralf T1 - First passage time distribution in heterogeneity controlled kinetics: going beyond the mean first passage time JF - Scientific reports N2 - The first passage is a generic concept for quantifying when a random quantity such as the position of a diffusing molecule or the value of a stock crosses a preset threshold (target) for the first time. The last decade saw an enlightening series of new results focusing mostly on the so-called mean and global first passage time (MFPT and GFPT, respectively) of such processes. Here we push the understanding of first passage processes one step further. For a simple heterogeneous system we derive rigorously the complete distribution of first passage times (FPTs). Our results demonstrate that the typical FPT significantly differs from the MFPT, which corresponds to the long time behaviour of the FPT distribution. Conversely, the short time behaviour is shown to correspond to trajectories connecting directly from the initial value to the target. Remarkably, we reveal a previously overlooked third characteristic time scale of the first passage dynamics mirroring brief excursion away from the target. Y1 - 2016 U6 - https://doi.org/10.1038/srep20349 SN - 2045-2322 VL - 6 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Gonzalez Manrique, Sergio Javier A1 - Kuckein, Christoph A1 - Pastor Yabar, A. A1 - Collados Vera, M. A1 - Denker, Carsten A1 - Fischer, C. E. A1 - Gömöry, P. A1 - Diercke, Andrea A1 - Gonzalez, N. Bello A1 - Schlichenmaier, R. A1 - Balthasar, H. A1 - Berkefeld, T. A1 - Feller, A. A1 - Hoch, S. A1 - Hofmann, A. A1 - Kneer, F. A1 - Lagg, A. A1 - Nicklas, H. A1 - Orozco Suarez, D. A1 - Schmidt, D. A1 - Schmidt, W. A1 - Sigwarth, M. A1 - Sobotka, M. A1 - Solanki, S. K. A1 - Soltau, D. A1 - Staude, J. A1 - Strassmeier, Klaus G. A1 - Verma, Meetu A1 - Volkmer, R. A1 - von der Lühe, O. A1 - Waldmann, T. T1 - Fitting peculiar spectral profiles in He I 10830 angstrom absorption features JF - Astronomische Nachrichten = Astronomical notes N2 - The new generation of solar instruments provides better spectral, spatial, and temporal resolution for a better understanding of the physical processes that take place on the Sun. Multiple-component profiles are more commonly observed with these instruments. Particularly, the He i 10830 triplet presents such peculiar spectral profiles, which give information on the velocity and magnetic fine structure of the upper chromosphere. The purpose of this investigation is to describe a technique to efficiently fit the two blended components of the He i 10830 triplet, which are commonly observed when two atmospheric components are located within the same resolution element. The observations used in this study were taken on 2015 April 17 with the very fast spectroscopic mode of the GREGOR Infrared Spectrograph (GRIS) attached to the 1.5-m GREGOR solar telescope, located at the Observatorio del Teide, Tenerife, Spain. We apply a double-Lorentzian fitting technique using Levenberg-Marquardt least-squares minimization. This technique is very simple and much faster than inversion codes. Line-of-sight Doppler velocities can be inferred for a whole map of pixels within just a few minutes. Our results show sub-and supersonic downflow velocities of up to 32 km s(-1) for the fast component in the vicinity of footpoints of filamentary structures. The slow component presents velocities close to rest. (C) 2016 WILEY-VCH Verlag GmbH& Co. KGaA, Weinheim KW - Sun: chromosphere KW - methods: data analysis KW - techniques: spectroscopic KW - line: profiles Y1 - 2016 U6 - https://doi.org/10.1002/asna.201512433 SN - 0004-6337 SN - 1521-3994 VL - 337 SP - 1057 EP - 1063 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Verma, Meetu A1 - Denker, Carsten A1 - Böhm, F. A1 - Balthasar, H. A1 - Fischer, C. E. A1 - Kuckein, Christoph A1 - Gonzalez, N. Bello A1 - Berkefeld, T. A1 - Collados Vera, M. A1 - Diercke, Andrea A1 - Feller, A. A1 - Gonzalez Manrique, Sergio Javier A1 - Hofmann, A. A1 - Lagg, A. A1 - Nicklas, H. A1 - Orozco Suarez, D. A1 - Pator Yabar, A. A1 - Rezaei, R. A1 - Schlichenmaier, R. A1 - Schmidt, D. A1 - Schmidt, W. A1 - Sigwarth, M. A1 - Sobotka, M. A1 - Solanki, S. K. A1 - Soltau, D. A1 - Staude, J. A1 - Strassmeier, Klaus G. A1 - Volkmer, R. A1 - von der Lühe, O. A1 - Waldmann, T. T1 - Flow and magnetic field properties in the trailing sunspots of active region NOAA 12396 JF - Astronomische Nachrichten = Astronomical notes N2 - 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 KW - Sun: magnetic fields KW - sunspots KW - methods: data analysis KW - techniques: polarimetric KW - techniques: spectroscopic Y1 - 2016 U6 - https://doi.org/10.1002/asna.201612447 SN - 0004-6337 SN - 1521-3994 VL - 337 SP - 1090 EP - 1098 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Fang, Lijia A1 - Holzmueller, Felix A1 - Matulaitis, Tomas A1 - Baasner, Anne A1 - Hauenstein, Christoph A1 - Benduhn, Johannes A1 - Schwarze, Martin A1 - Petrich, Annett A1 - Piersimoni, Fortunato A1 - Scholz, Reinhard A1 - Zeika, Olaf A1 - Koerner, Christian A1 - Neher, Dieter A1 - Vandewal, Koen A1 - Leo, Karl T1 - Fluorine-containing low-energy-gap organic dyes with low voltage losses for organic solar cells JF - Synthetic metals : the journal of electronic polymers and electronic molecular materials N2 - Fluorine-containing donor molecules TFTF, CNTF and PRTF are designed and isomer selectively synthesized for application in vacuum-deposited organic solar cells. These molecules comprise a donor acceptor molecular architecture incorporating thiophene and benzothiadiazole derivatives as the electron-donating and electron-withdrawing moieties, respectively. As opposed to previously reported materials from this class, PRTF can be purified by vacuum sublimation at moderate to high yields because of its higher volatility and better stabilization due to a stronger intramolecular hydrogen bond, as compared to TFTF and CNTF. The UV-vis absorption spectra of the three donors show an intense broadband absorption between 500 nm and 800 nm with, similar positions of their frontier energy levels. The photophysical properties of the three donor molecules are thoroughly tested and optimized in bulk heterojunction solar cells with C-60 as acceptor. PRTF shows the best performance, yielding power conversion efficiencies of up to 3.8%. Moreover, the voltage loss for the PRTF device due to the non radiative recombination of free charge carriers is exceptionally low (0.26 V) as compared to typical values for organic solar cells (>0.34V). (C) 2016 Published by Elsevier B.V. KW - (Z)-isomer KW - Donor materials KW - CH center dot center dot center dot F hydrogen bonds KW - Sublimation with good yield KW - Low voltage losses Y1 - 2016 U6 - https://doi.org/10.1016/j.synthmet.2016.10.025 SN - 0379-6779 VL - 222 SP - 232 EP - 239 PB - Elsevier CY - Lausanne ER - TY - JOUR A1 - Hic, Ceren A1 - Pradhan, Prajal A1 - Rybski, Diego A1 - Kropp, Jürgen T1 - Food Surplus and Its Climate Burdens JF - Geological Society of America bulletin N2 - Avoiding food loss and waste may counteract the increasing food demand and reduce greenhouse gas (GHG) emissions from the agricultural sector. This is crucial because of limited options available to increase food production. In the year 2010, food availability was 20% higher than was required on a global scale. Thus, a more sustainable food production and adjusted consumption would have positive environmental effects. This study provides a systematic approach to estimate consumer level food waste on a country scale and globally, based on food availability and requirements. The food requirement estimation considers demographic development, body weights, and physical activity levels. Surplus between food availability and requirements of a given country is considered as food waste. The global food requirement changed from 2,300 kcal/cap/day to 2,400 kcal/cap/day during the last 50 years, while food surplus grew from 310 kcal/cap/day to 510 kcal/cap/day. Similarly, GHG emissions related to the food surplus increased from 130 Mt CO2eq/yr to 530 Mt CO2eq/yr, an increase of more than 300%. Moreover, the global food surplus may increase up to 850 kcal/cap/day, while the total food requirement will increase only by 2%-20% by 2050. Consequently, GHG emissions associated with the food waste may also increase tremendously to 1.9-2.5 Gt CO2eq/yr. Y1 - 2016 U6 - https://doi.org/10.1021/acs.est.5b05088 SN - 0013-936X SN - 1520-5851 VL - 50 SP - 4269 EP - 4277 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Parezanovic, Vladimir A1 - Cordier, Laurent A1 - Spohn, Andreas A1 - Duriez, Thomas A1 - Noack, Bernd R. A1 - Bonnet, Jean-Paul A1 - Segond, Marc A1 - Abel, Markus A1 - Brunton, Steven L. T1 - Frequency selection by feedback control in a turbulent shear flow JF - Journal of fluid mechanics N2 - Many previous studies have shown that the turbulent mixing layer under periodic forcing tends to adopt a lock-on state, where the major portion of the fluctuations in the flow are synchronized at the forcing frequency. The goal of this experimental study is to apply closed-loop control in order to provoke the lock-on state, using information from the flow itself. We aim to determine the range of frequencies for which the closed-loop control can establish the lock-on, and what mechanisms are contributing to the selection of a feedback frequency. In order to expand the solution space for optimal closed-loop control laws, we use the genetic programming control (CPC) framework. The best closed-loop control laws obtained by CPC are analysed along with the associated physical mechanisms in the mixing layer flow. The resulting closed-loop control significantly outperforms open-loop forcing in terms of robustness to changes in the free-stream velocities. In addition, the selection of feedback frequencies is not locked to the most amplified local mode, but rather a range of frequencies around it. KW - free shear layers KW - instability control KW - turbulence control Y1 - 2016 U6 - https://doi.org/10.1017/jfm.2016.261 SN - 0022-1120 SN - 1469-7645 VL - 797 SP - 247 EP - 283 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Thiem, A. A1 - Bagheri, M. A1 - Grosse-Siestrup, C. A1 - Zehbe, Rolf T1 - Gelatin-poly(lactic-co-glycolic acid) scaffolds with oriented pore channel architecture - From in vitro to in vivo testing JF - Vision research : an international journal for functional aspects of vision. N2 - A gelatin-poly(lactic-co-glycolic acid), PLGA, composite scaffold, featuring a highly oriented pore channel structure, was developed as a template for articular cartilage regeneration. As a design principle the composite scaffold was optimized to contain only medical grade educts and accordingly no chemical cross linking agents or other toxicological relevant substances or methods were used. Scaffolds were synthesized using a freeze structuring method combined with an electrochemical process followed by freeze-drying. Finally, cross linking was performed using dehydrothermal treatment, which was simultaneously used for sterilization purposes. These composite scaffolds were analyzed in regard to structural and biomechanical properties, and to their degradation behavior. Furthermore, cell culture performance was tested using chondrocytes originated from joint articular cartilage tissue from 6 to 10 months old domestic pigs. Finally, the scaffolds were tested for tissue biocompatibility and their ability for tissue integration in a rat model. The scaffolds showed both excellent functional performance and high biocompatibility in vitro and in vivo. We expect that these gelatin-PLGA scaffolds can effectively support chondrogenesis in vivo demonstrating great potential for the use in cartilage defect treatment. (C) 2016 Elsevier B.V. All rights reserved. KW - Gelatin-PLGA Scaffold KW - Dehydrothermal cross linking KW - Cartilage tissue engineering KW - Biomechanics KW - Rat model Y1 - 2016 U6 - https://doi.org/10.1016/j.msec.2016.02.019 SN - 0928-4931 SN - 1873-0191 VL - 62 SP - 585 EP - 595 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kegeles, Alexander A1 - Oriti, Daniele T1 - Generalized conservation laws in non-local field theories JF - Journal of physics : A, Mathematical and theoretical N2 - We propose a geometrical treatment of symmetries in non-local field theories, where the non-locality is due to a lack of identification of field arguments in the action. We show that the existence of a symmetry of the action leads to a generalized conservation law, in which the usual conserved current acquires an additional non-local correction term, obtaining a generalization of the standard Noether theorem. We illustrate the general formalism by discussing the specific physical example of complex scalar field theory of the type describing the hydrodynamic approximation of Bose-Einstein condensates. We expect our analysis and results to be of particular interest for the group field theory formulation of quantum gravity. KW - conservation laws KW - non-local field theory KW - Noether theorem KW - group field theory Y1 - 2016 U6 - https://doi.org/10.1088/1751-8113/49/13/135401 SN - 1751-8113 SN - 1751-8121 VL - 49 SP - 119 EP - 134 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Mazurek, P. A1 - Yu, L. A1 - Gerhard, Reimund A1 - Wirges, Werner A1 - Skov, A. L. T1 - Glycerol as high-permittivity liquid filler in dielectric silicone elastomers JF - Journal of applied polymer science N2 - A recently reported novel class of elastomers was tested with respect to its dielectric properties. The new elastomer material is based on a commercially available poly(dimethylsiloxane) composition, which has been modified by embedding glycerol droplets into its matrix. The approach has two major advantages that make the material useful in a dielectric actuator. First, the glycerol droplets efficiently enhance the dielectric constant, which can reach astonishingly high values in the composite. Second, the liquid filler also acts as a softener that effectively decreases the elastic modulus of the composite. In combination with very low cost and easy preparation, the two property enhancements lead to an extremely attractive dielectric elastomer material. Experimental permittivity data are compared to various theoretical models that predict relative permittivity changes as a function of filler loading, and the applicability of the models is discussed. (c) 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44153. KW - crosslinking KW - dielectric properties KW - elastomers KW - sensors and actuators Y1 - 2016 U6 - https://doi.org/10.1002/app.44153 SN - 0021-8995 SN - 1097-4628 VL - 133 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Pavlenko, Elena S. A1 - Sander, Mathias A1 - Cui, Q. A1 - Bargheer, Matias T1 - Gold Nanorods Sense the Ultrafast Viscoelastic Deformation of Polymers upon Molecular Strain Actuation JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - On the basis of the layer-by-layer deposition of polyelectrolytes, we have designed hybrid nanolayer composites for integrated optoacoustic experiments. The femtosecond-laser-excitation of an Azo functionalized film launches nanoscale strain waves at GHz frequencies into a transparent polymer layer. Gold nanorods deposited on the surface sense the arrival of these hyper-sound-waves on the picosecond time scale via a modification of their longitudinal plasmon resonance. We simulated the strain waves using a simple linear masses-and-springs model, which yields good agreement with the observed time scales associated with the nanolayer thicknesses of the constituent materials. From systematic experiments with calibrated strain amplitudes we conclude that reversible viscoelastic deformations of the polyelectrolyte multilayers are triggered by ultrashort pressure transients of about 4 MPa. Our experiments show that strain-mediated interactions in nanoarchitectures composed of molecular photoswitches and plasmonic particles may be used to design new functionalities. The approach combines the highly flexible and cost-effective preparation of polyelectrolyte multilayers with ultrafast molecular strain actuation and plasmonic sensing. Although we use simple flat layered structures for demonstration, this new concept can be used for three-dimensional nanoassemblies with different functionalities. The ultrafast and reversible nature of the response is highly desirable, and the short wavelength associated with the high frequency of the hyper-sound-waves connecting photoactive molecules and nanoparticles inherently gives spectroscopic access to the nanoscale. High-frequency elastic moduli are derived from the ultrafast spectroscopy of the hypersonic response in polyelectrolyte multilayers. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jpcc.6b06915 SN - 1932-7447 VL - 120 SP - 24957 EP - 24964 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Rätzel, Dennis A1 - Wilkens, Martin A1 - Menzel, Ralf T1 - Gravitational properties of light BT - the gravitational field of a laser pulse JF - New journal of physics : the open-access journal for physics N2 - The gravitational field of a laser pulse of finite lifetime, is investigated in the framework of linearized gravity. Although the effects are very small, they may be of fundamental physical interest. It is shown that the gravitational field of a linearly polarized light pulse is modulated as the norm of the corresponding electric field strength, while no modulations arise for circular polarization. In general, the gravitational field is independent of the polarization direction. It is shown that all physical effects are confined to spherical shells expanding with the speed of light, and that these shells are imprints of the spacetime events representing emission and absorption of the pulse. Nearby test particles at rest are attracted towards the pulse trajectory by the gravitational field due to the emission of the pulse, and they are repelled from the pulse trajectory by the gravitational field due to its absorption. Examples are given for the size of the attractive effect. It is recovered that massless test particles do not experience any physical effect if they are co-propagating with the pulse, and that the acceleration of massless test particles counter-propagating with respect to the pulse is four times stronger than for massive particles at rest. The similarities between the gravitational effect of a laser pulse and Newtonian gravity in two dimensions are pointed out. The spacetime curvature close to the pulse is compared to that induced by gravitational waves from astronomical sources. KW - gravity KW - general relativity KW - laser pulses KW - electromagnetic radiation KW - linearized gravity KW - pp-wave solutions Y1 - 2016 U6 - https://doi.org/10.1088/1367-2630/18/2/023009 SN - 1367-2630 VL - 18 SP - 1 EP - 16 PB - IOP Science CY - London ER - TY - JOUR A1 - Rätzel, Dennis A1 - Wilkens, Martin A1 - Menzel, Ralf T1 - Gravitational properties of light-the gravitational field of a laser pulse JF - NEW JOURNAL OF PHYSICS N2 - The gravitational field of a laser pulse of finite lifetime, is investigated in the framework of linearized gravity. Although the effects are very small, they may be of fundamental physical interest. It is shown that the gravitational field of a linearly polarized light pulse is modulated as the norm of the corresponding electric field strength, while no modulations arise for circular polarization. In general, the gravitational field is independent of the polarization direction. It is shown that all physical effects are confined to spherical shells expanding with the speed of light, and that these shells are imprints of the spacetime events representing emission and absorption of the pulse. Nearby test particles at rest are attracted towards the pulse trajectory by the gravitational field due to the emission of the pulse, and they are repelled from the pulse trajectory by the gravitational field due to its absorption. Examples are given for the size of the attractive effect. It is recovered that massless test particles do not experience any physical effect if they are co-propagating with the pulse, and that the acceleration of massless test particles counter-propagating with respect to the pulse is four times stronger than for massive particles at rest. The similarities between the gravitational effect of a laser pulse and Newtonian gravity in two dimensions are pointed out. The spacetime curvature close to the pulse is compared to that induced by gravitational waves from astronomical sources. KW - gravity KW - general relativity KW - laser pulses KW - electromagnetic radiation KW - linearized gravity KW - pp-wave solutions Y1 - 2016 U6 - https://doi.org/10.1088/1367-2630/18/2/023009 SN - 1367-2630 VL - 18 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Schreck, Simon A1 - Pietzsch, Annette A1 - Kennedy, Brian A1 - Sathe, Conny A1 - Miedema, Piter S. A1 - Techert, Simone A1 - Strocov, Vladimir N. A1 - Schmitt, Thorsten A1 - Hennies, Franz A1 - Rubensson, Jan-Erik A1 - Föhlisch, Alexander T1 - Ground state potential energy surfaces around selected atoms from resonant inelastic x-ray scattering JF - Scientific reports N2 - Thermally driven chemistry as well as materials’ functionality are determined by the potential energy surface of a systems electronic ground state. This makes the potential energy surface a central and powerful concept in physics, chemistry and materials science. However, direct experimental access to the potential energy surface locally around atomic centers and to its long-range structure are lacking. Here we demonstrate how sub-natural linewidth resonant inelastic soft x-ray scattering at vibrational resolution is utilized to determine ground state potential energy surfaces locally and detect long-range changes of the potentials that are driven by local modifications. We show how the general concept is applicable not only to small isolated molecules such as O2 but also to strongly interacting systems such as the hydrogen bond network in liquid water. The weak perturbation to the potential energy surface through hydrogen bonding is observed as a trend towards softening of the ground state potential around the coordinating atom. The instrumental developments in high resolution resonant inelastic soft x-ray scattering are currently accelerating and will enable broad application of the presented approach. With this multidimensional potential energy surfaces that characterize collective phenomena such as (bio)molecular function or high-temperature superconductivity will become accessible in near future. Y1 - 2016 U6 - https://doi.org/10.1038/srep20054 SN - 2045-2322 VL - 6 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Hassanin, Alshaimaa A1 - Kliem, Bernhard A1 - Seehafer, Norbert T1 - Helical kink instability in the confined solar eruption on 2002 May 27 JF - Astronomische Nachrichten = Astronomical notes KW - instabilities KW - magnetohydrodynamics (MHD) KW - Sun: corona KW - Sun: coronal mass ejections (CMEs) KW - Sun: flares Y1 - 2016 U6 - https://doi.org/10.1002/asna.201612446 SN - 0004-6337 SN - 1521-3994 VL - 337 SP - 1082 EP - 1089 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Abdalla, Hassan E. A1 - Abramowski, Attila A1 - Aharonian, Felix A. A1 - Benkhali, Faical Ait A1 - Akhperjanian, A. G. A1 - Andersson, T. A1 - Angüner, Ekrem Oǧuzhan A1 - Arrieta, M. A1 - Aubert, Pierre A1 - Backes, Michael A1 - Balzer, Arnim A1 - Barnard, Michelle A1 - Becherini, Yvonne A1 - Tjus, J. Becker A1 - Berge, David A1 - Bernhard, Sabrina A1 - Bernlöhr, K. A1 - Birsin, E. A1 - Blackwell, R. A1 - Boettcher, Markus A1 - Boisson, Catherine A1 - Bolmont, J. A1 - Bordas, Pol A1 - Bregeon, Johan A1 - Brun, Francois A1 - Brun, Pierre A1 - Bryan, Mark A1 - Bulik, Tomasz A1 - Capasso, M. A1 - Carr, John A1 - Casanova, Sabrina A1 - Chakraborty, N. A1 - Chalme-Calvet, R. A1 - Chaves, Ryan C. G. A1 - Chen, Andrew A1 - Chevalier, J. A1 - Chretien, M. A1 - Colafrancesco, Sergio A1 - Cologna, Gabriele A1 - Condon, B. A1 - Conrad, Jan A1 - Couturier, C. A1 - Cui, Y. A1 - Davids, I. D. A1 - Degrange, B. A1 - Deil, C. A1 - Devin, J. A1 - de Wilt, P. A1 - Djannati-Ataie, A. A1 - Domainko, W. A1 - Donath, A. A1 - Dubus, G. A1 - Dutson, K. A1 - Dyks, J. A1 - Dyrda, M. A1 - Edwards, T. A1 - Egberts, Kathrin A1 - Eger, P. A1 - Ernenwein, J. -P. A1 - Eschbach, S. A1 - Farnier, C. A1 - Fegan, S. A1 - Fernandes, M. V. A1 - Fiasson, A. A1 - Fontaine, G. A1 - Foerster, A. A1 - Funk, S. A1 - Fuessling, M. A1 - Gabici, S. A1 - Gajdus, M. A1 - Gallant, Y. A. A1 - Garrigoux, T. A1 - Giavitto, G. A1 - Giebels, B. A1 - Glicenstein, J. F. A1 - Gottschall, D. A1 - Goyal, A. A1 - Grondin, M. -H. A1 - Grudzinska, M. A1 - Hadasch, D. A1 - Hahn, J. A1 - Hawkes, J. A1 - Heinzelmann, G. A1 - Henri, G. A1 - Hermann, G. A1 - Hervet, O. A1 - Hillert, A. A1 - Hinton, James Anthony A1 - Hofmann, W. A1 - Hoischen, Clemens A1 - Holler, M. A1 - Horns, D. A1 - Ivascenko, A. A1 - Jacholkowska, A. A1 - Jamrozy, M. A1 - Janiak, M. A1 - Jankowsky, D. A1 - Jankowsky, F. A1 - Jingo, M. A1 - Jogler, T. A1 - Jouvin, L. A1 - Jung-Richardt, I. A1 - Kastendieck, M. A. A1 - Katarzynski, K. A1 - Katz, U. A1 - Kerszberg, D. A1 - Khelifi, B. A1 - Kieffer, M. A1 - King, J. A1 - Klepser, S. A1 - Klochkov, D. A1 - Kluzniak, W. A1 - Kolitzus, D. A1 - Komin, Nu. A1 - Kosack, K. A1 - Krakau, S. A1 - Kraus, M. A1 - Krayzel, F. A1 - Krueger, P. P. A1 - Laffon, H. A1 - Lamanna, G. A1 - Lau, J. A1 - Lees, J. -P. A1 - Lefaucheur, J. A1 - Lefranc, V. A1 - Lemiere, A. A1 - Lemoine-Goumard, M. A1 - Lenain, J. -P. A1 - Leser, Eva A1 - Liu, R. A1 - Lohse, T. A1 - Lorentz, M. A1 - Lypova, I. A1 - Marandon, V. A1 - Marcowith, Alexandre A1 - Mariaud, C. A1 - Marx, R. A1 - Maurin, G. A1 - Maxted, N. A1 - Mayer, Michael A1 - Meintjes, P. J. A1 - Meyer, M. A1 - Mitchell, A. M. W. A1 - Moderski, R. A1 - Mohamed, M. A1 - Mora, K. A1 - Moulin, Emmanuel A1 - Murach, T. A1 - de Naurois, M. A1 - Niederwanger, F. A1 - Niemiec, J. A1 - Oakes, L. A1 - Odaka, H. A1 - Ohm, S. A1 - Ostrowski, M. A1 - Oettl, S. A1 - Oya, I. A1 - Padovani, M. A1 - Panter, M. A1 - Parsons, R. D. A1 - Arribas, M. Paz A1 - Pekeur, N. W. A1 - Pelletier, G. A1 - Perennes, C. A1 - Petrucci, P. -O. A1 - Peyaud, B. A1 - Pita, S. A1 - Poon, H. A1 - Prokhorov, D. A1 - Prokoph, H. A1 - Puehlhofer, G. A1 - Punch, M. A1 - Quirrenbach, A. A1 - Raab, S. A1 - Reimer, A. A1 - Reimer, O. A1 - Renaud, M. A1 - Reyes, R. de los A1 - Rieger, F. A1 - Romoli, C. A1 - Rosier-Lees, S. A1 - Rowell, G. A1 - Rudak, B. A1 - Rulten, C. B. A1 - Sahakian, V. A1 - Salek, D. A1 - Sanchez, David M. A1 - Santangelo, A. A1 - Sasaki, M. A1 - Schlickeiser, R. A1 - Schuessler, F. A1 - Schulz, A. A1 - Schwanke, U. A1 - Schwemmer, S. A1 - Settimo, M. A1 - Seyffert, A. S. A1 - Shafi, N. A1 - Shilon, I. A1 - Simoni, R. A1 - Sol, H. A1 - Spanier, F. A1 - Spengler, G. A1 - Spies, F. A1 - Stawarz, L. A1 - Steenkamp, R. A1 - Stegmann, Christian A1 - Stinzing, F. A1 - Stycz, K. A1 - Sushch, Iurii A1 - Tavernet, J. -P. A1 - Tavernier, T. A1 - Taylor, A. M. A1 - Terrier, R. A1 - Tibaldo, L. A1 - Tluczykont, M. A1 - Trichard, C. A1 - Tuffs, R. A1 - van der Walt, J. A1 - van Eldik, C. A1 - van Soelen, B. A1 - Vasileiadis, G. A1 - Veh, J. A1 - Venter, C. A1 - Viana, A. A1 - Vincent, P. A1 - Vink, J. A1 - Voisin, F. A1 - Voelk, H. J. A1 - Vuillaume, T. A1 - Wadiasingh, Z. A1 - Wagner, S. J. A1 - Wagner, P. A1 - Wagner, R. M. A1 - White, R. A1 - Wierzcholska, A. A1 - Willmann, P. A1 - Woernlein, A. A1 - Wouters, D. A1 - Yang, R. A1 - Zabalza, V. A1 - Zaborov, D. A1 - Zacharias, M. A1 - Zdziarski, A. A. A1 - Zech, Alraune A1 - Zefi, F. A1 - Ziegler, A. A1 - Zywucka, N. T1 - HESS Limits on Linelike Dark Matter Signatures in the 100 GeV to 2 TeV Energy Range Close to the Galactic Center JF - Physical review letters N2 - A search for dark matter linelike signals iss performed in the vicinity of the Galactic Center by the H.E.S.S. experiment on observational data taken in 2014. An unbinned likelihood analysis iss developed to improve the sensitivity to linelike signals. The upgraded analysis along with newer data extend the energy coverage of the previous measurement down to 100 GeV. The 18 h of data collected with the H.E.S.S. array allow one to rule out at 95% C.L. the presence of a 130 GeV line (at l = -1.5 degrees, b = 0 degrees and for a dark matter profile centered at this location) previously reported in Fermi-LAT data. This new analysis overlaps significantly in energy with previous Fermi-LAT and H.E.S.S. results. No significant excess associated with dark matter annihilations was found in the energy range of 100 GeV to 2 TeV and upper limits on the gamma-ray flux and the velocity weighted annihilation cross section are derived adopting an Einasto dark matter halo profile. Expected limits for present and future large statistics H.E.S.S. observations are also given. Y1 - 2016 U6 - https://doi.org/10.1103/PhysRevLett.117.151302 SN - 0031-9007 SN - 1079-7114 VL - 117 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Geiger, Tobias A1 - Frieler, Katja A1 - Levermann, Anders T1 - High-income does not protect against hurricane losses JF - Environmental research letters N2 - Damage due to tropical cyclones accounts for more than 50% of all meteorologically-induced economic losses worldwide. Their nominal impact is projected to increase substantially as the exposed population grows, per capita income increases, and anthropogenic climate change manifests. So far, historical losses due to tropical cyclones have been found to increase less than linearly with a nation's affected gross domestic product (GDP). Here we show that for the United States this scaling is caused by a sub-linear increase with affected population while relative losses scale super-linearly with per capita income. The finding is robust across a multitude of empirically derived damage models that link the storm's wind speed, exposed population, and per capita GDP to reported losses. The separation of both socio-economic predictors strongly affects the projection of potential future hurricane losses. Separating the effects of growth in population and per-capita income, per hurricane losses with respect to national GDP are projected to triple by the end of the century under unmitigated climate change, while they are estimated to decrease slightly without the separation. KW - climate change KW - tropical cyclones KW - damage KW - meteorological extremes KW - vulnerability Y1 - 2016 U6 - https://doi.org/10.1088/1748-9326/11/8/084012 SN - 1748-9326 VL - 11 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Ryabchun, Alexander A1 - Kollosche, Matthias A1 - Wegener, Michael A1 - Sakhno, Oksana T1 - Holographic Structuring of Elastomer Actuator: First True Monolithic Tunable Elastomer Optics JF - Advanced materials N2 - Volume diffraction gratings (VDGs) are inscribed selectively by diffusive introduction of benzophenone and subsequent UV-holographic structuring into an electroactive dielectric elastomer actuator (DEA), to afford a continuous voltage-controlled grating shift of 17%. The internal stress coupling of DEA and optical domain allows for a new generation of true monolithic tunable elastomer optics with voltage controlled properties. Y1 - 2016 U6 - https://doi.org/10.1002/adma.201602881 SN - 0935-9648 SN - 1521-4095 VL - 28 SP - 10217 EP - 10223 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Verma, Meetu A1 - Denker, Carsten A1 - Balthasar, H. A1 - Kuckein, Christoph A1 - González Manrique, Sergio Javier A1 - Sobotka, M. A1 - Gonzalez, N. Bello A1 - Hoch, S. A1 - Diercke, Andrea A1 - Kummerow, Philipp A1 - Berkefeld, T. A1 - Collados Vera, M. A1 - Feller, A. A1 - Hofmann, A. A1 - Kneer, F. A1 - Lagg, A. A1 - Löhner-Böttcher, J. A1 - Nicklas, H. A1 - Pastor Yabar, A. A1 - Schlichenmaier, R. A1 - Schmidt, D. A1 - Schmidt, W. A1 - Schubert, M. A1 - Sigwarth, M. A1 - Solanki, S. K. A1 - Soltau, D. A1 - Staude, J. A1 - Strassmeier, Klaus G. A1 - Volkmer, R. A1 - von der Lühe, O. A1 - Waldmann, T. T1 - Horizontal flow fields in and around a small active region The transition period between flux emergence and decay JF - Polymers N2 - 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. KW - Sun: photosphere KW - Sun: magnetic fields KW - techniques: image processing KW - methods: data analysis Y1 - 2016 U6 - https://doi.org/10.1051/0004-6361/201628380 SN - 1432-0746 VL - 596 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Sandin, C. A1 - Steffen, M. A1 - Schoenberner, D. A1 - Rühling, Ute T1 - Hot bubbles of planetary nebulae with hydrogen-deficient winds I. Heat conduction in a chemically stratified plasma JF - Frontiers in psychology N2 - Heat conduction has been found a plausible solution to explain discrepancies between expected and measured temperatures in hot bubbles of planetary nebulae (PNe). While the heat conduction process depends on the chemical composition, to date it has been exclusively studied for pure hydrogen plasmas in PNe. A smaller population of PNe show hydrogen-deficient and helium-and carbon-enriched surfaces surrounded by bubbles of the same composition; considerable differences are expected in physical properties of these objects in comparison to the pure hydrogen case. The aim of this study is to explore how a chemistry-dependent formulation of the heat conduction affects physical properties and how it affects the X-ray emission from PN bubbles of hydrogen-deficient stars. We extend the description of heat conduction in our radiation hydrodynamics code to work with any chemical composition. We then compare the bubble-formation process with a representative PN model using both the new and the old descriptions. We also compare differences in the resulting X-ray temperature and luminosity observables of the two descriptions. The improved equations show that the heat conduction in our representative model of a hydrogen-deficient PN is nearly as efficient with the chemistry-dependent description; a lower value on the diffusion coefficient is compensated by a slightly steeper temperature gradient. The bubble becomes somewhat hotter with the improved equations, but differences are otherwise minute. The observable properties of the bubble in terms of the X-ray temperature and luminosity are seemingly unaffected. KW - conduction KW - hydrodynamics KW - planetary nebulae: general KW - stars: AGB and post-AGB KW - stars: Wolf-Rayet KW - X-rays: stars Y1 - 2016 U6 - https://doi.org/10.1051/0004-6361/201527357 SN - 1432-0746 VL - 586 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Lechleitner, Franziska A. A1 - Baldini, James U. L. A1 - Breitenbach, Sebastian Franz Martin A1 - Fohlmeister, Jens Bernd A1 - McIntyre, Cameron A1 - Goswami, Bedartha A1 - Jamieson, Robert A. A1 - van der Voort, Tessa S. A1 - Prufer, Keith A1 - Marwan, Norbert A1 - Culleton, Brendan J. A1 - Kennett, Douglas J. A1 - Asmerom, Yemane A1 - Polyak, Victor A1 - Eglinton, Timothy I. T1 - Hydrological and climatological controls on radiocarbon concentrations in a tropical stalagmite JF - Geochimica et cosmochimica acta : journal of the Geochemical Society and the Meteoritical Society N2 - Precisely-dated stalagmites are increasingly important archives for the reconstruction of terrestrial paleoclimate at very high temporal resolution. In-depth understanding of local conditions at the cave site and of the processes driving stalagmite deposition is of paramount importance for interpreting proxy signals incorporated in stalagmite carbonate. Here we present a sub-decadally resolved dead carbon fraction (DCF) record for a stalagmite from Yok Balum Cave (southern Belize). The record is coupled to parallel stable carbon isotope (delta C-13) and U/Ca measurements, as well as radiocarbon (C-14) measurements from soils overlying the cave system. Using a karst carbon cycle model we disentangle the importance of soil and karst processes on stalagmite DCF incorporation, revealing a dominant host rock dissolution control on total DCF. Covariation between DCF, delta C-13, and U/Ca indicates that karst processes are a common driver of all three parameters, suggesting possible use of delta C-13 and trace element ratios to independently quantify DCF variability. A statistically significant multi-decadal lag of variable length exists between DCF and reconstructed solar activity, suggesting that solar activity influenced regional precipitation in Mesoamerica over the past 1500 years, but that the relationship was non-static. Although the precise nature of the observed lag is unclear, solar-induced changes in North Atlantic oceanic and atmospheric dynamics may play a role. (C) 2016 Elsevier Ltd. All rights reserved. KW - Stalagmite KW - Tropics KW - Radiocarbon KW - Trace elements KW - Hydroclimate Y1 - 2016 U6 - https://doi.org/10.1016/j.gca.2016.08.039 SN - 0016-7037 SN - 1872-9533 VL - 194 SP - 233 EP - 252 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Shashev, Yury A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Müller, Bernd R. A1 - Bruno, Giovanni T1 - Improving the visibility of phase gratings for Talbot-Lau X-ray imaging JF - Materials testing : Materialprüfung ; materials and components, technology and application N2 - Talbot-Lau interferometry provides X-ray imaging techniques with significant enhancement of the radiographic contrast of weakly absorbing objects. The grating based technique allows separation of absorption, refraction and small angle scattering effects. The different efficiency of rectangular and triangular shaped phase gratings at varying detector distances is investigated. The interference patterns (Talbot carpets) are modeled for parallel monochromatic radiation and measured by synchrotron radiation. In comparison to rectangular shapes of phase gratings much higher visibility is obtained for triangular shapes which yield enhanced contrast of a glass capillary test specimen. KW - Talbot-Lau interferometry KW - phase grating KW - synchrotron imaging KW - visibility KW - X-ray refraction Y1 - 2016 U6 - https://doi.org/10.3139/120.110948 SN - 0025-5300 VL - 58 SP - 970 EP - 974 PB - Hanser CY - München ER - TY - JOUR A1 - Martinez Gonzalez, M. J. A1 - Pastor Yabar, A. A1 - Lagg, A. A1 - Asensio Ramos, A. A1 - Collados Vera, M. A1 - Solanki, S. K. A1 - Balthasar, H. A1 - Berkefeld, T. A1 - Denker, Carsten A1 - Doerr, H. P. A1 - Feller, A. A1 - Franz, M. A1 - González Manrique, Sergio Javier A1 - Hofmann, A. A1 - Kneer, F. A1 - Kuckein, Christoph A1 - Louis, R. A1 - von der Lühe, O. A1 - Nicklas, H. A1 - Orozco, D. A1 - Rezaei, R. A1 - Schlichenmaier, R. A1 - Schmidt, D. A1 - Schmidt, W. A1 - Sigwarth, M. A1 - Sobotka, M. A1 - Soltau, D. A1 - Staude, J. A1 - Strassmeier, Klaus G. A1 - Verma, Meetu A1 - Waldman, T. A1 - Volkmer, R. T1 - Inference of magnetic fields in the very quiet Sun JF - Journal of geophysical research : Earth surface N2 - Context. Over the past 20 yr, the quietest areas of the solar surface have revealed a weak but extremely dynamic magnetism occurring at small scales (<500 km), which may provide an important contribution to the dynamics and energetics of the outer layers of the atmosphere. Understanding this magnetism requires the inference of physical quantities from high-sensitivity spectro-polarimetric data with high spatio-temporal resolution. Aims. We present high-precision spectro-polarimetric data with high spatial resolution (0.4") of the very quiet Sun at 1.56 mu m obtained with the GREGOR telescope to shed some light on this complex magnetism. Methods. We used inversion techniques in two main approaches. First, we assumed that the observed profiles can be reproduced with a constant magnetic field atmosphere embedded in a field-free medium. Second, we assumed that the resolution element has a substructure with either two constant magnetic atmospheres or a single magnetic atmosphere with gradients of the physical quantities along the optical depth, both coexisting with a global stray-light component. Results. Half of our observed quiet-Sun region is better explained by magnetic substructure within the resolution element. However, we cannot distinguish whether this substructure comes from gradients of the physical parameters along the line of sight or from horizontal gradients (across the surface). In these pixels, a model with two magnetic components is preferred, and we find two distinct magnetic field populations. The population with the larger filling factor has very weak (similar to 150 G) horizontal fields similar to those obtained in previous works. We demonstrate that the field vector of this population is not constrained by the observations, given the spatial resolution and polarimetric accuracy of our data. The topology of the other component with the smaller filling factor is constrained by the observations for field strengths above 250 G: we infer hG fields with inclinations and azimuth values compatible with an isotropic distribution. The filling factors are typically below 30%. We also find that the flux of the two polarities is not balanced. From the other half of the observed quiet-Sun area similar to 50% are two-lobed Stokes V profiles, meaning that 23% of the field of view can be adequately explained with a single constant magnetic field embedded in a non-magnetic atmosphere. The magnetic field vector and filling factor are reliable inferred in only 50% based on the regular profiles. Therefore, 12% of the field of view harbour hG fields with filling factors typically below 30%. At our present spatial resolution, 70% of the pixels apparently are non-magnetised. KW - Sun: atmosphere KW - Sun: magnetic fields KW - techniques: polarimetric KW - methods: observational Y1 - 2016 U6 - https://doi.org/10.1051/0004-6361/201628449 SN - 1432-0746 VL - 596 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Holländer, Lars A1 - Kossack, Wilhelm A1 - Kollosche, Matthias A1 - Wirges, Werner A1 - Kremer, Friedrich A1 - Gerhard, Reimund T1 - Influence of the remanent polarisation on the liquid crystal alignment in composite films of ferroelectric poly(vinylidene fluoride-trifluoroethylene) and a cyanobiphenyl-based liquid crystal JF - Liquid crystals : an international journal of science and technology N2 - Polymer-dispersed liquid crystals (PDLCs) of ferroelectric poly(vinylidene fluoride-trifluoroethylene) and nematic 4-cyano-4ʹ-n-hexylbiphenyl (6CB) or 4-cyano-4ʹ-n-pentylbiphenyl (5CB) were prepared to study the effect of the remanent polarisation of the polymer on the liquid crystal alignment. We measured the macroscopic alignment of the liquid crystal molecules in the thickness direction by means of Infrared Transition-Moment Orientational Analysis. Electrical poling at 100 V/µm caused an increased order parameter up to 0.15. After subsequent annealing above the nematic-to-isotropic phase-transition temperature, the order parameter was reduced to 0.02. Nevertheless, the order parameter was still higher than for non-poled film indicating a slight orientation in thickness direction. Both values are lower than those expected from model calculations. In agreement with dielectric measurements, we attribute this result to the shielding effect of mobile charge carriers within the liquid crystal inclusions. KW - Polymer-dispersed liquid crystal KW - ferroelectric polymer KW - remanent polarisation KW - liquid crystal alignment Y1 - 2016 U6 - https://doi.org/10.1080/02678292.2016.1185174 SN - 0267-8292 SN - 1366-5855 VL - 43 SP - 1514 EP - 1521 PB - Editions Rodopi BV CY - Abingdon ER - TY - JOUR A1 - Ghosh, Surya K. A1 - Cherstvy, Andrey G. A1 - Petrov, Eugene P. A1 - Metzler, Ralf T1 - Interactions of rod-like particles on responsive elastic sheets JF - Soft matter N2 - What are the physical laws of the mutual interactions of objects bound to cell membranes, such as various membrane proteins or elongated virus particles? To rationalise this, we here investigate by extensive computer simulations mutual interactions of rod-like particles adsorbed on the surface of responsive elastic two-dimensional sheets. Specifically, we quantify sheet deformations as a response to adhesion of such filamentous particles. We demonstrate that tip-to-tip contacts of rods are favoured for relatively soft sheets, while side-by-side contacts are preferred for stiffer elastic substrates. These attractive orientation-dependent substrate-mediated interactions between the rod-like particles on responsive sheets can drive their aggregation and self-assembly. The optimal orientation of the membrane-bound rods is established via responding to the elastic energy profiles created around the particles. We unveil the phase diagramme of attractive–repulsive rod–rod interactions in the plane of their separation and mutual orientation. Applications of our results to other systems featuring membrane-associated particles are also discussed. Y1 - 2016 U6 - https://doi.org/10.1039/C6SM01522K SN - 1744-6848 SN - 1744-683X PB - RSC CY - London ER - TY - JOUR A1 - Ghosh, Surya K. A1 - Cherstvy, Andrey G. A1 - Petrov, Eugene P. A1 - Metzler, Ralf T1 - Interactions of rod-like particles on responsive elastic sheets JF - Soft matter N2 - What are the physical laws of the mutual interactions of objects bound to cell membranes, such as various membrane proteins or elongated virus particles? To rationalise this, we here investigate by extensive computer simulations mutual interactions of rod-like particles adsorbed on the surface of responsive elastic two-dimensional sheets. Specifically, we quantify sheet deformations as a response to adhesion of such filamentous particles. We demonstrate that tip-to-tip contacts of rods are favoured for relatively soft sheets, while side-by-side contacts are preferred for stiffer elastic substrates. These attractive orientation-dependent substrate-mediated interactions between the rod-like particles on responsive sheets can drive their aggregation and self-assembly. The optimal orientation of the membrane-bound rods is established via responding to the elastic energy profiles created around the particles. We unveil the phase diagramme of attractive-repulsive rod-rod interactions in the plane of their separation and mutual orientation. Applications of our results to other systems featuring membrane-associated particles are also discussed. Y1 - 2016 U6 - https://doi.org/10.1039/c6sm01522k SN - 1744-683X SN - 1744-6848 VL - 12 SP - 7908 EP - 7919 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Pimenova, Anastasiya V. A1 - Goldobin, Denis S. A1 - Rosenblum, Michael A1 - Pikovskij, Arkadij T1 - Interplay of coupling and common noise at the transition to synchrony in oscillator populations JF - Scientific reports N2 - There are two ways to synchronize oscillators: by coupling and by common forcing, which can be pure noise. By virtue of the Ott-Antonsen ansatz for sine-coupled phase oscillators, we obtain analytically tractable equations for the case where both coupling and common noise are present. While noise always tends to synchronize the phase oscillators, the repulsive coupling can act against synchrony, and we focus on this nontrivial situation. For identical oscillators, the fully synchronous state remains stable for small repulsive coupling; moreover it is an absorbing state which always wins over the asynchronous regime. For oscillators with a distribution of natural frequencies, we report on a counter-intuitive effect of dispersion (instead of usual convergence) of the oscillators frequencies at synchrony; the latter effect disappears if noise vanishes. Y1 - 2016 U6 - https://doi.org/10.1038/srep38518 SN - 2045-2322 VL - 6 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Zehbe, Kerstin A1 - Kollosche, Matthias A1 - Lardong, Sebastian A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Taubert, Andreas T1 - Ionogels Based on Poly(methyl methacrylate) and Metal-Containing Ionic Liquids: Correlation between Structure and Mechanical and Electrical Properties JF - International journal of molecular sciences N2 - Ionogels (IGs) based on poly(methyl methacrylate) (PMMA) and the metal-containing ionic liquids (ILs) bis-1-butyl-3-methlimidazolium tetrachloridocuprate(II), tetrachloride cobaltate(II), and tetrachlorido manganate(II) have been synthesized and their mechanical and electrical properties have been correlated with their microstructure. Unlike many previous examples, the current IGs show a decreasing stability in stress-strain experiments on increasing IL fractions. The conductivities of the current IGs are lower than those observed in similar examples in the literature. Both effects are caused by a two-phase structure with micrometer-sized IL-rich domains homogeneously dispersed an IL-deficient continuous PMMA phase. This study demonstrates that the IL-polymer miscibility and the morphology of the IGs are key parameters to control the (macroscopic) properties of IGs. KW - microstructure KW - ionogels KW - ionic liquids KW - phase separation KW - mechanical properties KW - ionic conductivity Y1 - 2016 U6 - https://doi.org/10.3390/ijms17030391 SN - 1422-0067 VL - 17 PB - MDPI CY - Basel ER - TY - JOUR A1 - Schreck, Simon A1 - Wernet, Philippe T1 - Isotope effects in liquid water probed by transmission mode x-ray absorption spectroscopy at the oxygen K-edge JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - The effects of isotope substitution in liquid water are probed by x-ray absorption spectroscopy at the O K-edge as measured in transmission mode. Confirming earlier x-ray Raman scattering experiments, the D2O spectrum is found to be blue shifted with respect to H2O, and the D2O spectrum to be less broadened. Following the earlier interpretations of UV and x-ray Raman spectra, the shift is related to the difference in ground-state zero-point energies between D2O and H2O, while the difference in broadening is related to the difference in ground-state vibrational zero-point distributions. We demonstrate that the transmission-mode measurements allow for determining the spectral shapes with unprecedented accuracy. Owing in addition to the increased spectral resolution and signal to noise ratio compared to the earlier measurements, the new data enable the stringent determination of blue shift and broadening in the O K-edge x-ray absorption spectrum of liquid water upon isotope substitution. The results are compared to UV absorption data, and it is discussed to which extent they reflect the differences in zero-point energies and vibrational zero-point distributions in the ground-states of the liquids. The influence of the shape of the final-state potential, inclusion of the Franck-Condon structure, and differences between liquid H2O and D2O resulting from different hydrogen-bond environments in the liquids are addressed. The differences between the O K-edge absorption spectra of water from our transmission-mode measurements and from the state-of-the-art x-ray Raman scattering experiments are discussed in addition. The experimentally extracted values of blue shift and broadening are proposed to serve as a test for calculations of ground-state zero-point energies and vibrational zero-point distributions in liquid H2O and D2O. This clearly motivates the need for new calculations of the O K-edge x-ray absorption spectrum of liquid water. Published by AIP Publishing. Y1 - 2016 U6 - https://doi.org/10.1063/1.4962237 SN - 0021-9606 SN - 1089-7690 VL - 145 SP - 24 EP - 32 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Rettig, L. A1 - Dornes, C. A1 - Thielemann-Kuehn, Nele A1 - Pontius, N. A1 - Zabel, Hartmut A1 - Schlagel, D. L. A1 - Lograsso, T. A. A1 - Chollet, M. A1 - Robert, A. A1 - Sikorski, M. A1 - Song, S. A1 - Glownia, J. M. A1 - Schuessler-Langeheine, Christian A1 - Johnson, S. L. A1 - Staub, U. T1 - Itinerant and Localized Magnetization Dynamics in Antiferromagnetic Ho JF - Physical review letters N2 - Using femtosecond time-resolved resonant magnetic x-ray diffraction at the Ho L-3 absorption edge, we investigate the demagnetization dynamics in antiferromagnetically ordered metallic Ho after femtosecond optical excitation. Tuning the x-ray energy to the electric dipole (E1, 2p -> 5d) or quadrupole (E2, 2p -> 4f) transition allows us to selectively and independently study the spin dynamics of the itinerant 5d and localized 4f electronic subsystems via the suppression of the magnetic (2 1 3-tau) satellite peak. We find demagnetization time scales very similar to ferromagnetic 4f systems, suggesting that the loss of magnetic order occurs via a similar spin-flip process in both cases. The simultaneous demagnetization of both subsystems demonstrates strong intra-atomic 4f-5d exchange coupling. In addition, an ultrafast lattice contraction due to the release of magneto-striction leads to a transient shift of the magnetic satellite peak. Y1 - 2016 U6 - https://doi.org/10.1103/PhysRevLett.116.257202 SN - 0031-9007 SN - 1079-7114 VL - 116 SP - 6382 EP - 6389 PB - American Physical Society CY - College Park ER -