TY - JOUR A1 - Stange, Maike A1 - Hintsche, Marius A1 - Sachse, Kirsten A1 - Gerhardt, Matthias A1 - Valleriani, Angelo A1 - Beta, Carsten T1 - Analyzing the spatial positioning of nuclei in polynuclear giant cells JF - Journal of Physics D: Applied Physics N2 - How cells establish and maintain a well-defined size is a fundamental question of cell biology. Here we investigated to what extent the microtubule cytoskeleton can set a predefined cell size, independent of an enclosing cell membrane. We used electropulse-induced cell fusion to form giant multinuclear cells of the social amoeba Dictyostelium discoideum. Based on dual-color confocal imaging of cells that expressed fluorescent markers for the cell nucleus and the microtubules, we determined the subcellular distributions of nuclei and centrosomes in the giant cells. Our two- and three-dimensional imaging results showed that the positions of nuclei in giant cells do not fall onto a regular lattice. However, a comparison with model predictions for random positioning showed that the subcellular arrangement of nuclei maintains a low but still detectable degree of ordering. This can be explained by the steric requirements of the microtubule cytoskeleton, as confirmed by the effect of a microtubule degrading drug. KW - Dictyostelium KW - cell nucleus KW - positioning KW - imaging KW - spatial poisson distribution Y1 - 2017 U6 - https://doi.org/10.1088/1361-6463/aa8da0 SN - 0022-3727 SN - 1361-6463 VL - 50 IS - 46 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - El-Nagar, Gumaa A. A1 - Sarhan, Radwan Mohamed A1 - Abouserie, Ahed A1 - Maticiuc, Natalia A1 - Bargheer, Matias A1 - Lauermann, Iver A1 - Roth, Christina T1 - Efficient 3D-Silver Flower-like Microstructures for Non-Enzymatic Hydrogen Peroxide (H2O2) Amperometric Detection JF - Scientific reports Y1 - 2017 U6 - https://doi.org/10.1038/s41598-017-11965-9 SN - 2045-2322 VL - 7 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Goychuk, Igor T1 - Fractional Bhatnagar-Gross-Krook kinetic equation JF - The European physical journal : B, Condensed matter and complex systems N2 - The linear Boltzmann equation approach is generalized to describe fractional superdiffusive transport of the Levy walk type in external force fields. The time distribution between scattering events is assumed to have a finite mean value and infinite variance. It is completely characterized by the two scattering rates, one fractional and a normal one, which defines also the mean scattering rate. We formulate a general fractional linear Boltzmann equation approach and exemplify it with a particularly simple case of the Bohm and Gross scattering integral leading to a fractional generalization of the Bhatnagar, Gross and Krook kinetic equation. Here, at each scattering event the particle velocity is completely randomized and takes a value from equilibrium Maxwell distribution at a given fixed temperature. We show that the retardation effects are indispensable even in the limit of infinite mean scattering rate and argue that this novel fractional kinetic equation provides a viable alternative to the fractional Kramers-Fokker-Planck (KFP) equation by Barkai and Silbey and its generalization by Friedrich et al. based on the picture of divergent mean time between scattering events. The case of divergent mean time is also discussed at length and compared with the earlier results obtained within the fractional KFP. Also a phenomenological fractional BGK equation without retardation effects is proposed in the limit of infinite scattering rates. It cannot be, however, rigorously derived from a scattering model, being rather clever postulated. It this respect, this retardationless equation is similar to the fractional KFP by Barkai and Silbey. However, it corresponds to the opposite, much more physical limit and, therefore, also presents a viable alternative. Y1 - 2017 U6 - https://doi.org/10.1140/epjb/e2017-80297-x SN - 1434-6028 SN - 1434-6036 VL - 90 PB - Springer CY - New York ER - TY - JOUR A1 - Delle Side, Domenico A1 - Nassisi, Vincenzo A1 - Pennetta, Cecilia A1 - Alifano, Pietro A1 - Di Salvo, Marco A1 - Tala, Adelfia A1 - Chechkin, Aleksei V. A1 - Seno, Flavio A1 - Trovato, Antonio T1 - Bacterial bioluminescence onset and quenching: a dynamical model for a quorum sensing-mediated property JF - Royal Society Open Science N2 - We present an effective dynamical model for the onset of bacterial bioluminescence, one of the most studied quorum sensing-mediated traits. Our model is built upon simple equations that describe the growth of the bacterial colony, the production and accumulation of autoinducer signal molecules, their sensing within bacterial cells, and the ensuing quorum activation mechanism that triggers bioluminescent emission. The model is directly tested to quantitatively reproduce the experimental distributions of photon emission times, previously measured for bacterial colonies of Vibrio jasicida, a luminescent bacterium belonging to the Harveyi clade, growing in a highly drying environment. A distinctive and novel feature of the proposed model is bioluminescence ‘quenching’ after a given time elapsed from activation. Using an advanced fitting procedure based on the simulated annealing algorithm, we are able to infer from the experimental observations the biochemical parameters used in the model. Such parameters are in good agreement with the literature data. As a further result, we find that, at least in our experimental conditions, light emission in bioluminescent bacteria appears to originate from a subtle balance between colony growth and quorum activation due to autoinducers diffusion, with the two phenomena occurring on the same time scale. This finding is consistent with a negative feedback mechanism previously reported for Vibrio harveyi. KW - quorum sensing KW - bioluminescence KW - biophysical model KW - Vibrio Harveyi clade KW - oxygen quenching KW - Gompertz growth function Y1 - 2017 U6 - https://doi.org/10.1098/rsos.171586 SN - 2054-5703 VL - 4 PB - Royal Society CY - London ER - TY - JOUR A1 - Javanainen, Matti A1 - Martinez-Seara, Hector A1 - Metzler, Ralf A1 - Vattulainen, Ilpo T1 - Diffusion of Integral Membrane Proteins in Protein-Rich Membranes JF - The journal of physical chemistry letters N2 - The lateral diffusion of embedded proteins along lipid membranes in protein-poor conditions has been successfully described in terms of the Saffman-Delbruck (SD) model, which predicts that the protein diffusion coefficient D is weakly dependent on its radius R as D proportional to ln(1/R). However, instead of being protein-poor, native cell membranes are extremely crowded with proteins. On the basis of extensive molecular simulations, we here demonstrate that protein crowding of the membrane at physiological levels leads to deviations from the SD relation and to the emergence of a stronger Stokes-like dependence D proportional to 1/R. We propose that this 1/R law mainly arises due to geometrical factors: smaller proteins are able to avoid confinement effects much better than their larger counterparts. The results highlight that the lateral dynamics in the crowded setting found in native membranes is radically different from protein-poor conditions and plays a significant role in formation of functional multiprotein complexes. Y1 - 2017 U6 - https://doi.org/10.1021/acs.jpclett.7b01758 SN - 1948-7185 VL - 8 SP - 4308 EP - 4313 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Palyulin, Vladimir V. A1 - Mantsevich, Vladimir N. A1 - Klages, Rainer A1 - Metzler, Ralf A1 - Chechkin, Aleksei V. T1 - Comparison of pure and combined search strategies for single and multiple targets JF - The European physical journal : B, Condensed matter and complex systems N2 - We address the generic problem of random search for a point-like target on a line. Using the measures of search reliability and efficiency to quantify the random search quality, we compare Brownian search with Levy search based on long-tailed jump length distributions. We then compare these results with a search process combined of two different long-tailed jump length distributions. Moreover, we study the case of multiple targets located by a Levy searcher. Y1 - 2017 U6 - https://doi.org/10.1140/epjb/e2017-80372-4 SN - 1434-6028 SN - 1434-6036 VL - 90 SP - 20 EP - 37 PB - Springer CY - New York ER - TY - JOUR A1 - Caetano, Daniel L. Z. A1 - de Carvalho, Sidney J. A1 - Metzler, Ralf A1 - Cherstvy, Andrey G. T1 - Critical adsorption of periodic and random polyampholytes onto charged surfaces JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - How different are the properties of critical adsorption of polyampholytes and polyelectrolytes onto charged surfaces? How important are the details of polyampholyte charge distribution on the onset of critical adsorption transition? What are the scaling relations governing the dependence of critical surface charge density on salt concentration in the surrounding solution? Here, we employ Metropolis Monte Carlo simulations and uncover the scaling relations for critical adsorption for quenched periodic and random charge distributions along the polyampholyte chains. We also evaluate and discuss the dependence of the adsorbed layer width on solution salinity and details of the charge distribution. We contrast our findings to the known results for polyelectrolyte adsorption onto oppositely charged surfaces, in particular, their dependence on electrolyte concentration. Y1 - 2017 U6 - https://doi.org/10.1039/c7cp04040g SN - 1463-9076 SN - 1463-9084 VL - 19 SP - 23397 EP - 23413 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Muench, Thomas A1 - Kipfstuhl, Sepp A1 - Freitag, Johannes A1 - Meyer, Hanno A1 - Laepple, Thomas T1 - Constraints on post-depositional isotope modifications in East Antarctic firn from analysing temporal changes of isotope profiles JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union N2 - The isotopic composition of water in ice sheets is extensively used to infer past climate changes. In low-accumulation regions their interpretation is, however, challenged by poorly constrained effects that may influence the initial isotope signal during and after deposition of the snow. This is reflected in snow-pit isotope data from Kohnen Station, Antarctica, which exhibit a seasonal cycle but also strong interannual variations that contradict local temperature observations. These inconsistencies persist even after averaging many profiles and are thus not explained by local stratigraphic noise. Previous studies have suggested that post-depositional processes may significantly influence the isotopic composition of East Antarctic firn. Here, we investigate the importance of post-depositional processes within the open-porous firn (greater than or similar to 10 cm depth) at Kohnen Station by separating spatial from temporal variability. To this end, we analyse 22 isotope profiles obtained from two snow trenches and examine the temporal isotope modifications by comparing the new data with published trench data extracted 2 years earlier. The initial isotope profiles undergo changes over time due to downward advection, firn diffusion and densification in magnitudes consistent with independent estimates. Beyond that, we find further modifications of the original isotope record to be unlikely or small in magnitude (<< 1 parts per thousand RMSD). These results show that the discrepancy between local temperatures and isotopes most likely originates from spatially coherent processes prior to or during deposition, such as precipitation intermittency or systematic isotope modifications acting on drifting or loose surface snow. Y1 - 2017 U6 - https://doi.org/10.5194/tc-11-2175-2017 SN - 1994-0416 SN - 1994-0424 VL - 11 SP - 2175 EP - 2188 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Starkenburg, Else A1 - Martin, Nicolas A1 - Youakim, Kris A1 - Aguado, David S. A1 - Allende Prieto, Carlos A1 - Arentsen, Anke A1 - Bernard, Edouard J. A1 - Bonifacio, Piercarlo A1 - Caffau, Elisabetta A1 - Carlberg, Raymond G. A1 - Cote, Patrick A1 - Fouesneau, Morgan A1 - Francois, Patrick A1 - Franke, Oliver A1 - Gonzalez Hernandez, Jonay I. A1 - Gwyn, Stephen D. J. A1 - Hill, Vanessa A1 - Ibata, Rodrigo A. A1 - Jablonka, Pascale A1 - Longeard, Nicolas A1 - McConnachie, Alan W. A1 - Navarro, Julio F. A1 - Sanchez-Janssen, Ruben A1 - Tolstoy, Eline A1 - Venn, Kim A. T1 - The Pristine survey - I. Mining the Galaxy for the most metal-poor stars JF - Monthly notices of the Royal Astronomical Society N2 - We present the Pristine survey, a new narrow-band photometric survey focused on the metallicity-sensitive Ca H&K lines and conducted in the Northern hemisphere with the wide-field imager MegaCam on the Canada-France-Hawaii Telescope. This paper reviews our overall survey strategy and discusses the data processing and metallicity calibration. Additionally we review the application of these data to the main aims of the survey, which are to gather a large sample of the most metal-poor stars in the Galaxy, to further characterize the faintest Milky Way satellites, and to map the (metal-poor) substructure in the Galactic halo. The current Pristine footprint comprises over 1000 deg(2) in the Galactic halo ranging from b similar to 30 degrees to similar to 78 degrees and covers many known stellar substructures. We demonstrate that, for Sloan Digital Sky Survey (SDSS) stellar objects, we can calibrate the photometry at the 0.02-mag level. The comparison with existing spectroscopic metallicities from SDSS/Sloan Extension for Galactic Understanding and Exploration (SEGUE) and Large Sky Area Multi-Object Fiber Spectroscopic Telescope shows that, when combined with SDSS broad-band g and i photometry, we can use the CaHK photometry to infer photometric metallicities with an accuracy of similar to 0.2 dex from [Fe/H] = -0.5 down to the extremely metal-poor regime ([Fe/H] < -3.0). After the removal of various contaminants, we can efficiently select metal-poor stars and build a very complete sample with high purity. The success rate of uncovering [Fe/H](SEGUE) < -3.0 stars among [Fe/H](Pristine) < -3.0 selected stars is 24 per cent, and 85 per cent of the remaining candidates are still very metal poor ([Fe/H]<-2.0). We further demonstrate that Pristine is well suited to identify the very rare and pristine Galactic stars with [Fe/H] < -4.0, which can teach us valuable lessons about the early Universe. KW - stars: abundances KW - Galaxy: abundances KW - Galaxy: evolution KW - Galaxy: formation KW - Galaxy: halo KW - galaxies: dwarf Y1 - 2017 U6 - https://doi.org/10.1093/mnras/stx1068 SN - 0035-8711 SN - 1365-2966 VL - 471 SP - 2587 EP - 2604 PB - Oxford Univ. Press CY - Oxford ER - TY - GEN A1 - Erra, Ramon Guevara A1 - Velazquez, Jose L. Perez A1 - Rosenblum, Michael T1 - Neural Synchronization from the Perspective of Non-linear Dynamics T2 - Frontiers in computational neuroscience / Frontiers Research Foundation KW - brain synchronization KW - non-linear dynamics KW - neural synchonization KW - brain rhythms KW - epilepsy Y1 - 2017 U6 - https://doi.org/10.3389/fncom.2017.00098 SN - 1662-5188 VL - 11 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Sander, Mathias A1 - Herzog, Marc A1 - Pudell, Jan-Etienne A1 - Bargheer, Matias A1 - Weinkauf, N. A1 - Pedersen, M. A1 - Newby, G. A1 - Sellmann, J. A1 - Schwarzkopf, J. A1 - Besse, V. A1 - Temnov, V. V. A1 - Gaal, P. T1 - Spatiotemporal Coherent Control of Thermal Excitations in Solids JF - Physical review letters N2 - X-ray reflectivity measurements of femtosecond laser-induced transient gratings (TG) are applied to demonstrate the spatiotemporal coherent control of thermally induced surface deformations on ultrafast time scales. Using grazing incidence x-ray diffraction we unambiguously measure the amplitude of transient surface deformations with sub-angstrom resolution. Understanding the dynamics of femtosecond TG excitations in terms of superposition of acoustic and thermal gratings makes it possible to develop new ways of coherent control in x-ray diffraction experiments. Being the dominant source of TG signal, the long-living thermal grating with spatial period. can be canceled by a second, time-delayed TG excitation shifted by Lambda/2. The ultimate speed limits of such an ultrafast x-ray shutter are inferred from the detailed analysis of thermal and acoustic dynamics in TG experiments. Y1 - 2017 U6 - https://doi.org/10.1103/PhysRevLett.119.075901 SN - 0031-9007 SN - 1079-7114 VL - 119 SP - 102 EP - 110 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Arora, Ashima A1 - Mawass, Mohamad-Assaad A1 - Sandig, Oliver A1 - Luo, Chen A1 - Uenal, Ahmet A. A1 - Radu, Florin A1 - Valencia, Sergio A1 - Kronast, Florian T1 - Spatially resolved investigation of all optical magnetization switching in TbFe alloys JF - Scientific reports N2 - Optical control of magnetization using femtosecond laser without applying any external magnetic field offers the advantage of switching magnetic states at ultrashort time scales. Recently, all-optical helicity-dependent switching (AO-HDS) has drawn a significant attention for potential information and data storage device applications. In this work, we employ element and magnetization sensitive photoemission electron microscopy (PEEM) to investigate the role of heating in AO-HDS for thin films of the rare-earth transition-metal alloy TbFe. Spatially resolved measurements in a 3–5 μm sized stationary laser spot demonstrate that AO-HDS is a local phenomenon in the vicinity of thermal demagnetization in a ‘ring’ shaped region. The efficiency of AO-HDS further depends on a local temperature profile around the demagnetized region and thermally activated domain wall motion. We also demonstrate that the thickness of the film determines the preferential switching direction for a particular helicity. Y1 - 2017 U6 - https://doi.org/10.1038/s41598-017-09615-1 SN - 2045-2322 VL - 7 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Mor, Selene A1 - Herzog, Marc A1 - Golez, Denis A1 - Werner, Philipp A1 - Eckstein, Martin A1 - Katayama, Naoyuki A1 - Nohara, Minoru A1 - Takagi, Hide A1 - Mizokawa, Takashi A1 - Monney, Claude A1 - Staehler, Julia T1 - Ultrafast Electronic Band Gap Control in an Excitonic Insulator JF - Physical review letters N2 - We report on the nonequilibrium dynamics of the electronic structure of the layered semiconductor Ta2NiSe5 investigated by time-and angle-resolved photoelectron spectroscopy. We show that below the critical excitation density of F-C = 0.2 mJ cm(-2), the band gap narrows transiently, while it is enhanced above FC. Hartree-Fock calculations reveal that this effect can be explained by the presence of the low-temperature excitonic insulator phase of Ta2NiSe5, whose order parameter is connected to the gap size. This work demonstrates the ability to manipulate the band gap of Ta2NiSe5 with light on the femtosecond time scale. Y1 - 2017 U6 - https://doi.org/10.1103/PhysRevLett.119.086401 SN - 0031-9007 SN - 1079-7114 VL - 119 SP - 11559 EP - 11567 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Yoon, P. H. A1 - Lopez, R. A. A1 - Vafin, Sergei A1 - Kim, S. A1 - Schlickeiser, R. T1 - Spontaneous emission of Alfvenic fluctuations JF - Plasma physics and controlled fusion N2 - Low-frequency fluctuations are pervasively observed in the solar wind. The present paper theoretically calculates the steady state spectra of low-frequency electromagnetic (EM) fluctuations of the Alfvenic type for thermal equilibrium plasma. The analysis is based upon a recently formulated theory of spontaneously emitted EM fluctuations in magnetized thermal plasmas. It is found that the fluctuations in the magnetosonic mode branch is constant, while the kinetic Alfvenic mode spectrum is dependent on a form factor that is a function of perpendicular wave number. Potential applicability of the present work in the wider context of heliospheric research is also discussed. KW - spontaneous emission KW - kinetic Alfven KW - magnetosonic Y1 - 2017 U6 - https://doi.org/10.1088/1361-6587/aa77c3 SN - 0741-3335 SN - 1361-6587 VL - 59 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Cherstvy, Andrey G. T1 - Shape Morphologies of Icosahedral Two-Component Vesicles JF - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry N2 - What are the features of partitioning of crystalline materials on the surface of a two-component icosahedral vesicle? We model the response of the rigid hardly stretchable crystalline icosahedra upon addition of a softer component on its surface. We demonstrate how the soft phase "invades" the shell regions with the highest elastic energy density around 12 5-fold topological defects. We explore the phase diagram of these inhomogeneous shells as a function of the soft material fraction, shell radius, and elastic moduli of the two phases. The findings are compared with the recent computer simulation findings, and their biological relevance, for example, for the structure of icosahedral viruses, is also discussed. Y1 - 2017 U6 - https://doi.org/10.1021/acs.jpcb.7b02440 SN - 1520-6106 VL - 121 SP - 7484 EP - 7491 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Raju, Rajarshi Roy A1 - Kosmella, Sabine A1 - Friberg, Stig E. A1 - Koetz, Joachim T1 - Pickering Janus emulsions and polyelectrolyte complex-stabilized Janus gels JF - Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects N2 - Janus emulsions, containing olive oil (OO) and silicone oil (SiO), were formed in presence of polyelectrolyte complex particles, i.e., gelatin-sodium polyacrylate (NaPAA) complexes. The diameter of completely engulfed Janus droplets can be tuned between 50 and 200 mu m by varying the gelatin/NaPAA complex particle size between 200 and 400 nm. The gelatin/NaPAA complex particles adsorbed at the olive oil interface decrease the interfacial tension and stabilize the resulting completely engulfed Pickering Janus emulsions. Long-term stable Janus gels can be synthesized in presence of gelatin/sodium carboxymethylcellulose (NaCMC) mixtures. In that case Coulombic forces are of relevance with regard to the stabilization of the Janus droplets embedded in a gelatin/NaCMC gel matrix. Janus gels show elastic reological behavior and thixotropic properties. KW - Pickering Janus emulsions KW - Janus gels KW - Interfacial tension KW - Ring tensiometry KW - Gelatin-NaCMC KW - Gelatin-NaPAA composites Y1 - 2017 U6 - https://doi.org/10.1016/j.colsurfa.2017.08.022 SN - 0927-7757 SN - 1873-4359 VL - 533 SP - 241 EP - 248 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kurzke, Henning A1 - Kiethe, Jan A1 - Heuer, Axel A1 - Jechow, Andreas T1 - Frequency doubling of incoherent light from a superluminescent diode in a periodically poled lithium niobate waveguide crystal JF - Laser physics letters N2 - The amplified spontaneous emission from a superluminescent diode was frequency doubled in a periodically poled lithium niobate waveguide crystal. The temporally incoherent radiation of such a superluminescent diode is characterized by a relatively broad spectral bandwidth and thermal-like photon statistics, as the measured degree of second order coherence, g((2))(0)= 1.9 +/- 0.1, indicates. Despite the non-optimized scenario in the spectral domain, we achieve six orders of magnitude higher conversion efficiency than previously reported with truly incoherent light. This is possible by using single spatial mode radiation and quasi phase matched material with a waveguide architecture. This work is a principle step towards efficient frequency conversion of temporally incoherent radiation in one spatial mode to access wavelengths where no radiation from superluminescent diodes is available, especially with tailored quasi phase matched crystals. The frequency doubled light might find application in imaging, metrology and quantum optics experiments. KW - nonlinear frequency conversion KW - periodically poled material KW - waveguides KW - incoherent radiation Y1 - 2017 U6 - https://doi.org/10.1088/1612-202X/aa6889 SN - 1612-2011 SN - 1612-202X VL - 14 PB - IOP Publ. CY - Bristol ER - TY - JOUR A1 - Kamann, Sebastian A1 - Husser, T. -O. A1 - Dreizler, S. A1 - Emsellem, E. A1 - Weilbacher, Peter Michael A1 - Martens, S. A1 - Bacon, R. A1 - den Brok, M. A1 - Giesers, B. A1 - Krajnovic, Davor A1 - Roth, Martin M. A1 - Wendt, Martin A1 - Wisotzki, Lutz T1 - A stellar census in globular clusters with MUSE BT - the contribution of rotation to cluster dynamics studied with 200 000 stars JF - Monthly notices of the Royal Astronomical Society N2 - This is the first of a series of papers presenting the results from our survey of 25 Galactic globular clusters with the MUSE integral-field spectrograph. In combination with our dedicated algorithm for source deblending, MUSE provides unique multiplex capabilities in crowded stellar fields and allows us to acquire samples of up to 20 000 stars within the half-light radius of each cluster. The present paper focuses on the analysis of the internal dynamics of 22 out of the 25 clusters, using about 500 000 spectra of 200 000 individual stars. Thanks to the large stellar samples per cluster, we are able to perform a detailed analysis of the central rotation and dispersion fields using both radial profiles and two-dimensional maps. The velocity dispersion profiles we derive show a good general agreement with existing radial velocity studies but typically reach closer to the cluster centres. By comparison with proper motion data, we derive or update the dynamical distance estimates to 14 clusters. Compared to previous dynamical distance estimates for 47 Tuc, our value is in much better agreement with other methods. We further find significant (>3 sigma) rotation in the majority (13/22) of our clusters. Our analysis seems to confirm earlier findings of a link between rotation and the ellipticities of globular clusters. In addition, we find a correlation between the strengths of internal rotation and the relaxation times of the clusters, suggesting that the central rotation fields are relics of the cluster formation that are gradually dissipated via two-body relaxation. KW - techniques: imaging spectroscopy KW - stars: kinematics and dynamics KW - globular clusters: general Y1 - 2017 U6 - https://doi.org/10.1093/mnras/stx2719 SN - 0035-8711 SN - 1365-2966 VL - 473 IS - 4 SP - 5591 EP - 5616 PB - Oxford Univ. Press CY - Oxford ER - TY - GEN A1 - Javanainen, Matti A1 - Martinez-Seara, Hector A1 - Metzler, Ralf A1 - Vattulainen, Ilpo Tapio T1 - Diffusion of Proteins and Lipids in Protein-Rich Membranesa T2 - Biophysical journal Y1 - 2018 U6 - https://doi.org/10.1016/j.bpj.2017.11.3009 SN - 0006-3495 SN - 1542-0086 VL - 114 IS - 3 SP - 551A EP - 551A PB - Cell Press CY - Cambridge ER - TY - JOUR A1 - Pillitteri, Ignazio A1 - Fossati, Luca A1 - Rodriguez, N. Castro A1 - Oskinova, Lida A1 - Wolk, Scott J. T1 - Detection of magnetic field in the B2 star rho Ophiuchi A with ESO FORS2 JF - Astronomy and astrophysics : an international weekly journal N2 - Circumstantial evidence suggests that magnetism and enhanced X-ray emission are likely correlated in early B-type stars: similar fractions of them (similar to 10%) are strong and hard X-ray sources and possess strong magnetic fields. It is also known that some B-type stars have spots on their surface. Yet up to now no X-ray activity associated with spots on early-type stars was detected. In this Letter we report the detection of a magnetic field on the B2V star rho Oph A. Previously, we assessed that the X-ray activity of this star is associated with a surface spot, herewith we establish its magnetic origin. We analyze spectra of rho Oph A obtained with the FORS2 spectrograph at ESO Very Large Telescope (VLT) at two epochs, and detect a longitudinal component of the magnetic field of the order of similar to 500 G in one of the datasets. The detection of the magnetic field only at one epoch can be explained by stellar rotation which is also invoked to explain observed periodic X-ray activity. From archival HARPS ESO VLT high resolution spectra we derived the fundamental stellar parameters of rho Oph A and further constrained its age. We conclude that rho Oph A provides strong evidence for the presence of active X-ray emitting regions on young magnetized early type stars. KW - stars: activity KW - stars: early-type KW - stars: magnetic field KW - pulsars: individual: rho Ophiuchi A Y1 - 2017 U6 - https://doi.org/10.1051/0004-6361/201732078 SN - 1432-0746 VL - 610 PB - EDP Sciences CY - Les Ulis ER - TY - GEN A1 - Gudowska-Nowak, Ewa A1 - Lindenberg, Katja A1 - Metzler, Ralf T1 - Preface: Marian Smoluchowski’s 1916 paper—a century of inspiration T2 - Journal of physics : A, Mathematical and theoretical Y1 - 2017 U6 - https://doi.org/10.1088/1751-8121/aa8529 SN - 1751-8113 SN - 1751-8121 VL - 50 IS - 38 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Hani, Maan H. A1 - Sparre, Martin A1 - Ellison, Sara L. A1 - Torrey, Paul A1 - Vogelsberger, Mark T1 - Galaxy mergers moulding the circum-galactic medium BT - I. The impact of a major merger JF - Monthly notices of the Royal Astronomical Society N2 - Galaxies are surrounded by sizeable gas reservoirs which host a significant amount of metals: the circum-galactic medium (CGM). The CGM acts as a mediator between the galaxy and the extragalactic medium. However, our understanding of how galaxy mergers, a major evolutionary transformation, impact the CGM remains deficient. We present a theoretical study of the effect of galaxy mergers on the CGM. We use hydrodynamical cosmological zoom-in simulations of a major merger selected from the Illustris project such that the z = 0 descendant has a halo mass and stellar mass comparable to the Milky Way. To study the CGM we then re-simulated this system at a 40 times better mass resolution, and included detailed post-processing ionization modelling. Our work demonstrates the effect the merger has on the characteristic size of the CGM, its metallicity, and the predicted covering fraction of various commonly observed gas-phase species, such as H I, C IV, and O VI. We show that merger-induced outflows can increase the CGM metallicity by 0.2-0.3 dex within 0.5 Gyr post-merger. These effects last up to 6 Gyr post-merger. While the merger increases the total metal covering fractions by factors of 2-3, the covering fractions of commonly observed UV ions decrease due to the hard ionizing radiation from the active galactic nucleus, which we model explicitly. Our study of the single simulated major merger presented in this work demonstrates the significant impact that a galaxy interaction can have on the size, metallicity, and observed column densities of the CGM. KW - methods: numerical KW - galaxies: evolution KW - galaxies: haloes KW - galaxies: interactions Y1 - 2017 U6 - https://doi.org/10.1093/mnras/stx3252 SN - 0035-8711 SN - 1365-2966 VL - 475 IS - 1 SP - 1160 EP - 1176 PB - Oxford Univ. Press CY - Oxford ER - TY - GEN A1 - Parsons, R. D. A1 - Schüssler, F. A1 - Garrigoux, T. A1 - Balzer, A. A1 - Füssling, Matthias A1 - Hoischen, Clemens A1 - Holler, M. A1 - Mitchell, A. A1 - Pühlhofer, G. A1 - Rowell, G. A1 - Wagner, S. A1 - Bissaldi, E. A1 - Tam, P. H. T. T1 - The HESS II GRB Observation Scheme T2 - AIP conference proceedings / American Institute of Physics N2 - Gamma-ray bursts (GRBs) are some of the Universe’s most enigmatic and exotic events. However, at energies above 10 GeV their behaviour remains largely unknown. Although space based telescopes such as the Fermi-LAT have been able to detect GRBs in this energy range, their photon statistics are limited by the small detector size. Such limitations are not present in ground based gamma-ray telescopes such as the H.E.S.S. experiment, which has now entered its second phase with the addition of a large 600 m2 telescope to the centre of the array. Such a large telescope allows H.E.S.S. to access the sub 100-GeV energy range while still maintaining a large effective collection area, helping to potentially probe the short timescale emission of these events. We present a description of the H.E.S.S. GRB observation programme, summarising the performance of the rapid GRB repointing system and the conditions under which GRB observations are initiated. Additionally we will report on the GRB follow-ups made during the 2014-15 observation campaigns. Y1 - 2017 SN - 978-0-7354-1456-3 U6 - https://doi.org/10.1063/1.4968980 SN - 0094-243X SN - 1551-7616 VL - 1792 IS - 1 PB - American Institute of Physics CY - Melville ER - TY - GEN A1 - Angüner, Ekrem Oǧuzhan A1 - Aharonian, Felix A. A1 - Bordas, Pol A1 - Casanova, Sabrina A1 - Hoischen, Clemens A1 - Oya, I. A1 - Ziegler, A. T1 - HESS J1826-130 BT - a very hard gamma-Ray spectrum source in the Galactic Plane T2 - AIP conference proceedings / American Institute of Physics N2 - HESS J1826-130 is an unidentified hard spectrum source discovered by H.E.S.S. along the Galactic plane, the spectral index being Gamma = 1.6 with an exponential cut-off at about 12 TeV. While the source does not have a clear counterpart at longer wavelengths, the very hard spectrum emission at TeV energies implies that electrons or protons accelerated up to several hundreds of TeV are responsible for the emission. In the hadronic case, the VHE emission can be produced by runaway cosmic-rays colliding with the dense molecular clouds spatially coincident with the H.E.S.S. source. Y1 - 2017 SN - 978-0-7354-1456-3 U6 - https://doi.org/10.1063/1.4968928 SN - 0094-243X SN - 1551-7616 VL - 1792 IS - 1 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Beta, Carsten A1 - Kruse, Karsten T1 - Intracellular oscillations and waves JF - Annual review of condensed matter physics N2 - Dynamic processes in living cells are highly organized in space and time. Unraveling the underlying molecular mechanisms of spatiotemporal pattern formation remains one of the outstanding challenges at the interface between physics and biology. A fundamental recurrent pattern found in many different cell types is that of self-sustained oscillations. They are involved in a wide range of cellular functions, including second messenger signaling, gene expression, and cytoskeletal dynamics. Here, we review recent developments in the field of cellular oscillations and focus on cases where concepts from physics have been instrumental for understanding the underlying mechanisms. We consider biochemical and genetic oscillators as well as oscillations that arise from chemo-mechanical coupling. Finally, we highlight recent studies of intracellular waves that have increasingly moved into the focus of this research field. KW - self-sustained oscillations KW - biochemical oscillators KW - genetic networks KW - chemomechanical coupling KW - actin waves Y1 - 2017 SN - 978-0-8243-5008-6 U6 - https://doi.org/10.1146/annurev-conmatphys-031016-025210 SN - 1947-5454 VL - 8 SP - 239 EP - 264 PB - Annual Reviews CY - Palo Alto ER - TY - GEN A1 - Thoelert, Steffen A1 - Hörmann, Ulrich A1 - Antreich, Felix A1 - Meurer, Michael T1 - Ionospheric effects on high gain antenna GNSS measurements BT - TEC estimation and correction T2 - Proceedings of the 30th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2017) N2 - The ionospheric delay of global navigation satellite systems (GNSS) signals typically is compensated by adding a single correction value to the pseudorange measurement of a GNSS receiver. Yet, this neglects the dispersive nature of the ionosphere. In this context we analyze the ionospheric signal distortion beyond a constant delay. These effects become increasingly significant with the signal bandwidth and hence more important for new broadband navigation signals. Using measurements of the Galileo E5 signal, captured with a high gain antenna, we verify that the expected influence can indeed be observed and compensated. A new method to estimate the total electron content (TEC) from a single frequency high gain antenna measurement of a broadband GNSS signal is proposed and described in detail. The received signal is de facto unaffected by multi-path and interference because of the narrow aperture angle of the used antenna which should reduce the error source of the result in general. We would like to point out that such measurements are independent of code correlation, like in standard receiver applications. It is therefore also usable without knowledge of the signal coding. Results of the TEC estimation process are shown and discussed comparing to common TEC products like TEC maps and dual frequency receiver estimates. Y1 - 2017 U6 - https://doi.org/10.33012/2017.15343 SN - 2331-5911 SN - 2331-5954 SP - 3368 EP - 3374 PB - Instituite of Navigation CY - Washington ER - TY - THES A1 - Shenar, Tomer T1 - Comprehensive analyses of massive binaries and implications on stellar evolution T1 - Umfassende Analysen massereicher Doppelsterne und Implikationen für die Sternentwicklung N2 - Via their powerful radiation, stellar winds, and supernova explosions, massive stars (Mini & 8 M☉) bear a tremendous impact on galactic evolution. It became clear in recent decades that the majority of massive stars reside in binary systems. This thesis sets as a goal to quantify the impact of binarity (i.e., the presence of a companion star) on massive stars. For this purpose, massive binary systems in the Local Group, including OB-type binaries, high mass X-ray binaries (HMXBs), and Wolf-Rayet (WR) binaries, were investigated by means of spectral, orbital, and evolutionary analyses. The spectral analyses were performed with the non-local thermodynamic equillibrium (non-LTE) Potsdam Wolf-Rayet (PoWR) model atmosphere code. Thanks to critical updates in the calculation of the hydrostatic layers, the code became a state-of-the-art tool applicable for all types of hot massive stars (Chapter 2). The eclipsing OB-type triple system δ Ori served as an intriguing test-case for the new version of the PoWR code, and provided key insights regarding the formation of X-rays in massive stars (Chapter 3). We further analyzed two prototypical HMXBs, Vela X-1 and IGR J17544-2619, and obtained fundamental conclusions regarding the dichotomy of two basic classes of HMXBs (Chapter 4). We performed an exhaustive analysis of the binary R 145 in the Large Magellanic Cloud (LMC), which was claimed to host the most massive stars known. We were able to disentangle the spectrum of the system, and performed an orbital, polarimetric, and spectral analysis, as well as an analysis of the wind-wind collision region. The true masses of the binary components turned out to be significantly lower than suggested, impacting our understanding of the initial mass function and stellar evolution at low metallicity (Chapter 5). Finally, all known WR binaries in the Small Magellanic Cloud (SMC) were analyzed. Although it was theoretical predicted that virtually all WR stars in the SMC should be formed via mass-transfer in binaries, we find that binarity was not important for the formation of the known WR stars in the SMC, implying a strong discrepancy between theory and observations (Chapter 6). N2 - Durch ihre intensive Strahlung, Sternwinde und Supernovaexplosionen tragen massereiche Sterne (Minitial & 8 M☉) erheblich zur Entwicklung von Galaxien bei. In den letzten Jahren wurde es immer klarer, dass sich die Mehrheit der massereichen Sterne in Doppelsternsystemen befindet. Die vorliegende Doktorarbeit hat das Ziel, den Einfluss dieser Tatsache auf die Entwicklung massereicher Sterne quantitativ zu untersuchen. Um dies zu erreichen, haben wir eine Analyse der Umläufe, Spektren und Entwicklung verschiedener Doppelsternsysteme in der lokalen Gruppe durchgeführt, die OB-Sterne, massereicher Röntgendoppelsterne (HMXBs) und Wolf-Rayet-(WR)-Doppelsterne einschließt. Die Spektralanalyse wurde mithilfe des Potsdam-Wolf-Rayet-(PoWR)-Modellatmosphären-Programms für Strahlungstransport in Abwesenheit von lokalem thermodynamischen Gleichgewicht (non-LTE) durchgeführt. Das PoWR-Programm wurde im Laufe der Arbeit aktualisiert, sodass die Berechnung der hydrostatischen Schichten des Sternes nun wesentlich genauer erfolgt, was die Verwendung dieses Programms für alle Typen heißer massereicher Sterne erlaubte (Kapitel 2). Das bedeckungsveränderliche Dreifachsternsystem δ Ori diente als Test für diese neue Version von PoWR, und lieferte wesentliche Informationen bezüglich der Entstehung von Röntgenstrahlung in massereichen Sternen (Kapitel 3). Die Analyse zweier prototypischer massereicher Röntgendoppelsterne, Vela X-1 und IGR J17544-2619, machte den Ursprung der Dichotomie der zwei Hauptklassen der Röntgendoppelsterne deutlich (Kapitel 4). Eine umfassende Analyse des Doppelsterns R145 in der Großen Magellanschen Wolke (LMC), der angeblich aus den massereichsten uns bekannten Sternen besteht, wurde durchgeführt. Mithilfe einer Dekomposition des Spektrums, einer Orbital- und Spektralanalyse, sowie einer Analyse der Kollision von Sternwinden in diesem System konnten wir zeigen, dass die Massen der Komponenten wesentlich kleiner sind als bisher angenommen. Dies ist ein wichtiger Beitrag zu unserem Verständnis der Anfangsmassenfunktion und der Entwicklung massereicher Sterne in Umgebungen geringer Metalizität (Kapitel 5). Schließlich wurde die Gesamtpopulation der WR-Doppelsterne in der Kleinen Magellanschen Wolke (SMC) analysiert. Im Widerspruch zur theoretischen Vorhersage, alle WR-Doppelsterne in der SMC seien dank Massentransfer in Doppelsternsystemen entstanden, finden wir, dass Massentransfer unerheblich für die Entstehung der uns bekannten WR-Sterne in der SMC war (Kapitel 6). KW - massive stars KW - Wolf-Rayet KW - stellar evolution KW - stellar winds KW - binary stars KW - massereiche Sterne KW - Wolf-Rayet KW - Sternentwicklung KW - Sternwinde KW - Doppelsterne Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-104857 ER - TY - JOUR A1 - Mardoukhi, Ahmad A1 - Mardoukhi, Yousof A1 - Hokka, Mikko A1 - Kuokkala, Veli-Tapani T1 - Effects of strain rate and surface cracks on the mechanical behaviour of Balmoral Red granite JF - Philosophical Transactions of the Royal Society of London, Series A : Mathematical, Physical and Engineering Sciences N2 - This work presents a systematic study on the effects of strain rate and surface cracks on the mechanical properties and behaviour of Balmoral Red granite. The tensile behaviour of the rock was studied at low and high strain rates using Brazilian disc samples. Heat shocks were used to produce samples with different amounts of surface cracks. The surface crack patterns were analysed using optical microscopy, and the complexity of the patterns was quantified by calculating the fractal dimensions of the patterns. The strength of the rock clearly drops as a function of increasing fractal dimensions in the studied strain rate range. However, the dynamic strength of the rock drops significantly faster than the quasi-static strength, and, because of this, also the strain rate sensitivity of the rock decreases with increasing fractal dimensions. This can be explained by the fracture behaviour and fragmentation during the dynamic loading, which is more strongly affected by the heat shock than the fragmentation at low strain rates. KW - split Hopkinson pressure bar KW - rock KW - granite KW - dynamic loading KW - fractal dimension KW - surface cracks Y1 - 2017 U6 - https://doi.org/10.1098/rsta.2016.0179 SN - 1364-503X SN - 1471-2962 VL - 375 IS - 2085 PB - Royal Society CY - London ER - TY - JOUR A1 - Ahnen, M. L. A1 - Ansoldi, S. A1 - Antonelli, L. A. A1 - Antoranz, P. A1 - Babic, A. A1 - Banerjee, B. A1 - Bangale, P. A1 - de Almeida, U. Barres A1 - Barrio, J. A. A1 - Gonzalez, J. Becerra A1 - Bednarek, W. A1 - Bernardini, E. A1 - Berti, A. A1 - Biasuzzi, B. A1 - Biland, A. A1 - Blanch, O. A1 - Bonnefoy, S. A1 - Bonnoli, G. A1 - Borracci, F. A1 - Bretz, T. A1 - Buson, S. A1 - Carosi, A. A1 - Chatterjee, A. A1 - Clavero, R. A1 - Colin, P. A1 - Colombo, E. A1 - Contreras, J. L. A1 - Cortina, J. A1 - Covino, S. A1 - Da Vela, P. A1 - Dazzi, F. A1 - De Angelis, A. A1 - De Lotto, B. A1 - Wilhelmi, E. de Ona A1 - Di Pierro, F. A1 - Doert, M. A1 - Dominguez, A. A1 - Prester, D. Dominis A1 - Dorner, D. A1 - Doro, M. A1 - Einecke, S. A1 - Glawion, D. Eisenacher A1 - Elsaesser, D. A1 - Engelkemeier, M. A1 - Ramazani, V. Fallah A1 - Fernandez-Barral, A. A1 - Fidalgo, D. A1 - Fonseca, M. V. A1 - Font, L. A1 - Frantzen, K. A1 - Fruck, C. A1 - Galindo, D. A1 - Lopez, R. J. Garcia A1 - Garczarczyk, M. A1 - Terrats, D. Garrido A1 - Gaug, M. A1 - Giammaria, P. A1 - Godinovic, N. A1 - Gonzalez Munoz, A. A1 - Gora, D. A1 - Guberman, D. A1 - Hadasch, D. A1 - Hahn, A. A1 - Hanabata, Y. A1 - Hayashida, M. A1 - Herrera, J. A1 - Hose, J. A1 - Hrupec, D. A1 - Hughes, G. A1 - Idec, W. A1 - Kodani, K. A1 - Konno, Y. A1 - Kubo, H. A1 - Kushida, J. A1 - La Barbera, A. A1 - Lelas, D. A1 - Lindfors, E. A1 - Lombardi, S. A1 - Longo, F. A1 - Lopez, M. A1 - Lopez-Coto, R. A1 - Majumdar, P. A1 - Makariev, M. A1 - Mallot, K. A1 - Maneva, G. A1 - Manganaro, M. A1 - Mannheim, K. A1 - Maraschi, L. A1 - Marcote, B. A1 - Mariotti, M. A1 - Martinez, M. A1 - Mazin, D. A1 - Menzel, U. A1 - Miranda, J. M. A1 - Mirzoyan, R. A1 - Moralejo, A. A1 - Moretti, E. A1 - Nakajima, D. A1 - Neustroev, V. A1 - Niedzwiecki, A. A1 - Rosillo, M. Nievas A1 - Nilsson, K. A1 - Nishijima, K. A1 - Noda, K. A1 - Nogues, L. A1 - Overkemping, A. A1 - Paiano, S. A1 - Palacio, J. A1 - Palatiello, M. A1 - Paneque, D. A1 - Paoletti, R. A1 - Paredes, J. M. A1 - Paredes-Fortuny, X. A1 - Pedaletti, G. A1 - Peresano, M. A1 - Perri, L. A1 - Persic, M. A1 - Poutanen, J. A1 - Moroni, P. G. Prada A1 - Prandini, E. A1 - Puljak, I. A1 - Reichardt, I. A1 - Rhode, W. A1 - Ribo, M. A1 - Rico, J. A1 - Rodriguez Garcia, J. A1 - Saito, T. A1 - Satalecka, K. A1 - Schroder, S. A1 - Schultz, C. A1 - Schweizer, T. A1 - Shore, S. N. A1 - Sillanpaa, A. A1 - Sitarek, J. A1 - Snidaric, I. A1 - Sobczynska, D. A1 - Stamerra, A. A1 - Steinbring, T. A1 - Strzys, M. A1 - Suric, T. A1 - Takalo, L. A1 - Tavecchio, F. A1 - Temnikov, P. A1 - Terzic, T. A1 - Tescaro, D. A1 - Teshima, M. A1 - Thaele, J. A1 - Torres, D. F. A1 - Toyama, T. A1 - Treves, A. A1 - Vanzo, G. A1 - Verguilov, V. A1 - Vovk, I. A1 - Ward, J. E. A1 - Will, M. A1 - Wu, M. H. A1 - Zanin, R. A1 - Abeysekara, A. U. A1 - Archambault, S. A1 - Archer, A. A1 - Benbow, W. A1 - Bird, R. A1 - Buchovecky, M. A1 - Buckley, J. H. A1 - Bugaev, V. A1 - Connolly, M. P. A1 - Cui, W. A1 - Dickinson, H. J. A1 - Falcone, A. A1 - Feng, Q. A1 - Finley, J. P. A1 - Fleischhack, H. A1 - Flinders, A. A1 - Fortson, L. A1 - Gillanders, G. H. A1 - Griffin, S. A1 - Grube, J. A1 - Huetten, M. A1 - Hanna, D. A1 - Holder, J. A1 - Humensky, T. B. A1 - Kaaret, P. A1 - Kar, P. A1 - Kelley-Hoskins, N. A1 - Kertzman, M. A1 - Kieda, D. A1 - Krause, M. A1 - Krennrich, F. A1 - Lang, M. J. A1 - Maier, G. A1 - McCann, A. A1 - Moriarty, P. A1 - Mukherjee, R. A1 - Nieto, D. A1 - Ong, R. A. A1 - Otte, N. A1 - Park, N. A1 - Perkins, J. A1 - Pichel, A. A1 - Pohl, M. A1 - Popkow, A. A1 - Pueschel, Elisa A1 - Quinn, J. A1 - Ragan, K. A1 - Reynolds, P. T. A1 - Richards, G. T. A1 - Roache, E. A1 - Rovero, A. C. A1 - Rulten, C. A1 - Sadeh, I. A1 - Santander, M. A1 - Sembroski, G. H. A1 - Shahinyan, K. A1 - Telezhinsky, Igor O. A1 - Tucci, J. V. A1 - Tyler, J. A1 - Wakely, S. P. A1 - Weinstein, A. A1 - Wilcox, P. A1 - Wilhelm, Alina A1 - Williams, D. A. A1 - Zitzer, B. A1 - Razzaque, S. A1 - Villata, M. A1 - Raiteri, C. M. A1 - Aller, H. D. A1 - Aller, M. F. A1 - Larionov, V. M. A1 - Arkharov, A. A. A1 - Blinov, D. A. A1 - Efimova, N. V. A1 - Grishina, T. S. A1 - Hagen-Thorn, V. A. A1 - Kopatskaya, E. N. A1 - Larionova, L. V. A1 - Larionova, E. G. A1 - Morozova, D. A. A1 - Troitsky, I. S. A1 - Ligustri, R. A1 - Calcidese, P. A1 - Berdyugin, A. A1 - Kurtanidze, O. M. A1 - Nikolashvili, M. G. A1 - Kimeridze, G. N. A1 - Sigua, L. A. A1 - Kurtanidze, S. O. A1 - Chigladze, R. A. A1 - Chen, W. P. A1 - Koptelova, E. A1 - Sakamoto, T. A1 - Sadun, A. C. A1 - Moody, J. W. A1 - Pace, C. A1 - Pearson, R. A1 - Yatsu, Y. A1 - Mori, Y. A1 - Carraminyana, A. A1 - Carrasco, L. A1 - de la Fuente, E. A1 - Norris, J. P. A1 - Smith, P. S. A1 - Wehrle, A. A1 - Gurwell, M. A. A1 - Zook, A. A1 - Pagani, C. A1 - Perri, M. A1 - Capalbi, M. A1 - Cesarini, A. A1 - Krimm, H. A. A1 - Kovalev, Y. Y. A1 - Kovalev, Yu. A. A1 - Ros, E. A1 - Pushkarev, A. B. A1 - Lister, M. L. A1 - Sokolovsky, K. V. A1 - Kadler, M. A1 - Piner, G. A1 - Lahteenmaki, A. A1 - Tornikoski, M. A1 - Angelakis, E. A1 - Krichbaum, T. P. A1 - Nestoras, I. A1 - Fuhrmann, L. A1 - Zensus, J. A. A1 - Cassaro, P. A1 - Orlati, A. A1 - Maccaferri, G. A1 - Leto, P. A1 - Giroletti, M. A1 - Richards, J. L. A1 - Max-Moerbeck, W. A1 - Readhead, A. C. S. T1 - Multiband variability studies and novel broadband SED modeling of Mrk 501 in 2009 JF - Astronomy and astrophysics : an international weekly journal N2 - Aims. We present an extensive study of the BL Lac object Mrk 501 based on a data set collected during the multi-instrument campaign spanning from 2009 March 15 to 2009 August 1, which includes, among other instruments, MAGIC, VERITAS, Whipple 10 m, and Fermi-LAT to cover the gamma-ray range from 0.1 GeV to 20 TeV; RXTE and Swift to cover wavelengths from UV to hard X-rays; and GASP-WEBT, which provides coverage of radio and optical wavelengths. Optical polarization measurements were provided for a fraction of the campaign by the Steward and St. Petersburg observatories. We evaluate the variability of the source and interband correlations, the gamma-ray flaring activity occurring in May 2009, and interpret the results within two synchrotron self-Compton (SSC) scenarios. Methods. The multiband variability observed during the full campaign is addressed in terms of the fractional variability, and the possible correlations are studied by calculating the discrete correlation function for each pair of energy bands where the significance was evaluated with dedicated Monte Carlo simulations. The space of SSC model parameters is probed following a dedicated grid-scan strategy, allowing for a wide range of models to be tested and offering a study of the degeneracy of model-to-data agreement in the individual model parameters, hence providing a less biased interpretation than the "single-curve SSC model adjustment" typically reported in the literature. Results. We find an increase in the fractional variability with energy, while no significant interband correlations of flux changes are found on the basis of the acquired data set. The SSC model grid-scan shows that the flaring activity around May 22 cannot be modeled adequately with a one-zone SSC scenario (using an electron energy distribution with two breaks), while it can be suitably described within a two (independent) zone SSC scenario. Here, one zone is responsible for the quiescent emission from the averaged 4.5-month observing period, while the other one, which is spatially separated from the first, dominates the flaring emission occurring at X-rays and very-high-energy (> 100 GeV, VHE) gamma-rays. The flaring activity from May 1, which coincides with a rotation of the electric vector polarization angle (EVPA), cannot be satisfactorily reproduced by either a one-zone or a two-independent-zone SSC model, yet this is partially affected by the lack of strictly simultaneous observations and the presence of large flux changes on sub-hour timescales (detected at VHE gamma rays). Conclusions. The higher variability in the VHE emission and lack of correlation with the X-ray emission indicate that, at least during the 4.5-month observing campaign in 2009, the highest energy (and most variable) electrons that are responsible for the VHE gamma rays do not make a dominant contribution to the similar to 1 keV emission. Alternatively, there could be a very variable component contributing to the VHE gamma-ray emission in addition to that coming from the SSC scenario. The studies with our dedicated SSC grid-scan show that there is some degeneracy in both the one-zone and the two-zone SSC scenarios probed, with several combinations of model parameters yielding a similar model-to-data agreement, and some parameters better constrained than others. The observed gamma-ray flaring activity, with the EVPA rotation coincident with the first gamma-ray flare, resembles those reported previously for low frequency peaked blazars, hence suggesting that there are many similarities in the flaring mechanisms of blazars with different jet properties. KW - BL Lacertae objects: individual: Markarian 501 KW - methods: data analysis Y1 - 2017 U6 - https://doi.org/10.1051/0004-6361/201629540 SN - 1432-0746 VL - 603 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Xiong, Hui A1 - Mignolet, Benoit A1 - Fang, Li A1 - Osipov, Timur A1 - Wolf, Thomas J. A. A1 - Sistrunk, Emily A1 - Gühr, Markus A1 - Remacle, Francoise A1 - Berrah, Nora T1 - The Role of Super-Atom Molecular Orbitals in Doped Fullerenes in a Femtosecond Intense Laser Field JF - Scientific reports N2 - The interaction of gas phase endohedral fullerene Ho3N@C-80 with intense (0.1-5 x 10(14) W/cm(2)), short (30 fs), 800 nm laser pulses was investigated. The power law dependence of Ho3N@C-80(q+), q = 1-2, was found to be different from that of C-60. Time-dependent density functional theory computations revealed different light-induced ionization mechanisms. Unlike in C-60, in doped fullerenes, the breaking of the cage spherical symmetry makes super atomic molecular orbital (SAMO) states optically active. Theoretical calculations suggest that the fast ionization of the SAMO states in Ho3N@C-80 is responsible for the n = 3 power law for singly charged parent molecules at intensities lower than 1.2 x 10(14) W/cm(2). Y1 - 2017 U6 - https://doi.org/10.1038/s41598-017-00124-9 SN - 2045-2322 VL - 7 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Archambault, S. A1 - Archer, A. A1 - Benbow, W. A1 - Bird, R. A1 - Bourbeau, E. A1 - Brantseg, T. A1 - Buchovecky, M. A1 - Buckley, J. H. A1 - Bugaev, V. A1 - Byrum, K. A1 - Cerruti, M. A1 - Christiansen, J. L. A1 - Connolly, M. P. A1 - Cui, W. A1 - Daniel, M. K. A1 - Feng, Q. A1 - Finley, J. P. A1 - Fleischhack, H. A1 - Fortson, L. A1 - Furniss, A. A1 - Geringer-Sameth, A. A1 - Griffin, S. A1 - Grube, J. A1 - Hütten, M. A1 - Hakansson, N. A1 - Hanna, D. A1 - Hervet, O. A1 - Holder, J. A1 - Hughes, G. A1 - Hummensky, B. A1 - Johnson, C. A. A1 - Kaaret, P. A1 - Kar, P. A1 - Kelley-Hoskins, N. A1 - Kertzman, M. A1 - Kieda, D. A1 - Koushiappas, S. A1 - Krause, M. A1 - Krennrich, F. A1 - Lang, M. J. A1 - Lin, T. T. Y. A1 - McArthur, S. A1 - Moriarty, P. A1 - Mukherjee, R. A1 - Nieto, D. A1 - Ong, R. A. A1 - Otte, A. N. A1 - Park, N. A1 - Pohl, M. A1 - Popkow, A. A1 - Pueschel, Elisa A1 - Quinn, J. A1 - Ragan, K. A1 - Reynolds, P. T. A1 - Richards, G. T. A1 - Roache, E. A1 - Rulten, C. A1 - Sadeh, I. A1 - Santander, M. A1 - Sembroski, G. H. A1 - Shahinyan, K. A1 - Smith, A. W. A1 - Staszak, D. A1 - Telezhinsky, Igor O. A1 - Trepanier, S. A1 - Tucci, J. V. A1 - Tyler, J. A1 - Wakely, S. P. A1 - Weinstein, A. A1 - Wilcox, P. A1 - Williams, D. A. A1 - Zitzer, B. T1 - Dark matter constraints from a joint analysis of dwarf Spheroidal galaxy observations with VERITAS JF - Physical review : D, Particles, fields, gravitation, and cosmology N2 - We present constraints on the annihilation cross section of weakly interacting massive particles dark matter based on the joint statistical analysis of four dwarf galaxies with VERITAS. These results are derived from an optimized photon weighting statistical technique that improves on standard imaging atmospheric Cherenkov telescope (IACT) analyses by utilizing the spectral and spatial properties of individual photon events. We report on the results of similar to 230 hours of observations of five dwarf galaxies and the joint statistical analysis of four of the dwarf galaxies. We find no evidence of gamma-ray emission from any individual dwarf nor in the joint analysis. The derived upper limit on the dark matter annihilation cross section from the joint analysis is 1.35 x 10(-23) cm(3) s(-1) at 1 TeV for the bottom quark (b (b) over bar) final state, 2.85 x 10(-24) cm(3) s(-1) at 1 TeV for the tau lepton (tau+tau(-)) final state and 1.32 x 10-25 cm(3) s(-1) at 1 TeV for the gauge boson (gamma gamma) final state. Y1 - 2017 U6 - https://doi.org/10.1103/PhysRevD.95.082001 SN - 2470-0010 SN - 2470-0029 VL - 95 IS - 8 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Norregaard, Kamilla A1 - Metzler, Ralf A1 - Ritter, Christine M. A1 - Berg-Sorensen, Kirstine A1 - Oddershede, Lene Broeng T1 - Manipulation and Motion of Organelles and Single Molecules in Living Cells JF - Chemical reviews N2 - The biomolecule is among the most important building blocks of biological systems, and a full understanding of its function forms the scaffold for describing the mechanisms of higher order structures as organelles and cells. Force is a fundamental regulatory mechanism of biomolecular interactions driving many cellular processes. The forces on a molecular scale are exactly in the range that can be manipulated and probed with single molecule force spectroscopy. The natural environment of a biomolecule is inside a living cell, hence, this is the most relevant environment for probing their function. In vivo studies are, however, challenged by the complexity of the cell. In this review, we start with presenting relevant theoretical tools for analyzing single molecule data obtained in intracellular environments followed by a description of state-of-the art visualization techniques. The most commonly used force spectroscopy techniques, namely optical tweezers, magnetic tweezers, and atomic force microscopy, are described in detail, and their strength and limitations related to in vivo experiments are discussed. Finally, recent exciting discoveries within the field of in vivo manipulation and dynamics of single molecule and organelles are reviewed. Y1 - 2017 U6 - https://doi.org/10.1021/acs.chemrev.6b00638 SN - 0009-2665 SN - 1520-6890 VL - 117 IS - 5 SP - 4342 EP - 4375 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Leussu, R. A1 - Usoskin, IIlya G. A1 - Valliappan, Senthamizh Pavai A1 - Diercke, Andrea A1 - Arlt, Rainer A1 - Denker, Carsten A1 - Mursula, K. T1 - Wings of the butterfly BT - sunspot groups for 1826-2015 JF - Astronomy and astrophysics : an international weekly journal N2 - The spatio-temporal evolution of sunspot activity, the so-called Maunder butterfly diagram, has been continously available since 1874 using data from the Royal Greenwich Observatory, extended by SOON network data after 1976. Here we present a new extended butterfly diagram of sunspot group occurrence since 1826, using the recently digitized data from Schwabe (1826-1867) and Sporer (1866-1880). The wings of the diagram are separated using a recently developed method based on an analysis of long gaps in sunspot group occurrence in different latitude bands. We define characteristic latitudes, corresponding to the start, end, and the largest extent of the wings (the F, L, and H latitudes). The H latitudes (30 degrees-45 degrees) are highly significantly correlated with the strength of the wings (quantified by the total sum of the monthly numbers of sunspot groups). The F latitudes (20 degrees-30 degrees) depict a weak tendency, especially in the southern hemisphere, to follow the wing strength. The L latitudes (2 degrees-10 degrees) show no clear relation to the wing strength. Overall, stronger cycle wings tend to start at higher latitudes and have a greater wing extent. A strong (5-6)-cycle periodic oscillation is found in the start and end times of the wings and in the overlap and gaps between successive wings of one hemisphere. While the average wing overlap is zero in the southern hemisphere, it is two to three months in the north. A marginally significant oscillation of about ten solar cycles is found in the asymmetry of the L latitudes. The new long database of butterfly wings provides new observational constraints to solar dynamo models that discuss the spatio-temporal distribution of sunspot occurrence over the solar cycle and longer. KW - Sun: activity KW - sunspots KW - history and philosophy of astronomy Y1 - 2017 U6 - https://doi.org/10.1051/0004-6361/201629533 SN - 1432-0746 VL - 599 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Rätzel, Dennis A1 - Wilkens, Martin A1 - Menzel, Ralf T1 - Effect of polarization entanglement in photon-photon scattering JF - Physical review : A, Atomic, molecular, and optical physics N2 - It is found that the differential cross section of photon-photon scattering is a function of the degree of polarization entanglement of the two-photon state. A reduced general expression for the differential cross section of photon-photon scattering is derived by applying simple symmetry arguments. An explicit expression is obtained for the example of photon-photon scattering due to virtual electron-positron pairs in quantum electrodynamics. It is shown how the effect in this explicit example can be explained as an effect of quantum interference and that it fits with the idea of distance-dependent forces. Y1 - 2017 U6 - https://doi.org/10.1103/PhysRevA.95.012101 SN - 2469-9926 SN - 2469-9934 VL - 95 IS - 1 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Gong, Chen Chris A1 - Klumpp, Stefan T1 - Modeling sRNA-Regulated Plasmid Maintenance JF - PLoS one N2 - We study a theoretical model for the toxin-antitoxin (hok/sok) mechanism for plasmid maintenance in bacteria. Toxin-antitoxin systems enforce the maintenance of a plasmid through post-segregational killing of cells that have lost the plasmid. Key to their function is the tight regulation of expression of a protein toxin by an sRNA antitoxin. Here, we focus on the nonlinear nature of the regulatory circuit dynamics of the toxin-antitoxin mechanism. The mechanism relies on a transient increase in protein concentration rather than on the steady state of the genetic circuit. Through a systematic analysis of the parameter dependence of this transient increase, we confirm some known design features of this system and identify new ones: for an efficient toxin-antitoxin mechanism, the synthesis rate of the toxin’s mRNA template should be lower that of the sRNA antitoxin, the mRNA template should be more stable than the sRNA antitoxin, and the mRNA-sRNA complex should be more stable than the sRNA antitoxin. Moreover, a short half-life of the protein toxin is also beneficial to the function of the toxin-antitoxin system. In addition, we study a therapeutic scenario in which a competitor mRNA is introduced to sequester the sRNA antitoxin, causing the toxic protein to be expressed. Y1 - 2017 U6 - https://doi.org/10.1371/journal.pone.0169703 SN - 1932-6203 VL - 12 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Fandrich, Artur A1 - Buller, Jens A1 - Memczak, Henry A1 - Stoecklein, W. A1 - Hinrichs, K. A1 - Wischerhoff, E. A1 - Schulz, B. A1 - Laschewsky, André A1 - Lisdat, Fred T1 - Responsive Polymer-Electrode Interface-Study of its Thermo- and pH-Sensitivity and the Influence of Peptide Coupling JF - Electrochimica acta : the journal of the International Society of Electrochemistry (ISE) N2 - This study introduces a thermally responsive, polymer-based electrode system. The key component is a surface-attached, temperature-responsive poly(oligoethylene glycol) methacrylate (poly(OEGMA)) type polymer bearing photoreactive benzophenone and carboxy groups containing side chains. The responsive behavior of the polymer in aqueous media has been investigated by turbidimetry measurements. Polymer films are formed on gold substrates by means of the photoreactive 2(dicyclohexylphosphino)benzophenone (DPBP) through photocrosslinking. The electrochemical behavior of the resulting polymer-substrate interface has been investigated in buffered [Fe(CN)6](3-)/[Fe (CN)6](4-)solutions at room temperature and under temperature variation by cyclic voltammetry (CV). The CV experiments show that with increasing temperature structural changes of the polymer layer occur, which alter the output of the electrochemical measurement. Repeated heating/cooling cycles analyzed by CV measurements and pH changes analyzed by quartz crystal microbalance with dissipation monitoring (QCM-D) reveal the reversible nature of the restructuring process. The immobilized films are further modified by covalent coupling of two small biomolecules - a hydrophobic peptide and a more hydrophilic one. These attached components influence the hydrophobicity of the layer in a different way the resulting change of the temperature-caused behavior has been studied by CV indicating a different state of the polymer after coupling of the hydrophobic peptide. KW - Stimuli-responsive materials KW - electroanalysis KW - modified electrode KW - bioreceptors KW - peptides KW - surface modification KW - cyclic voltammetry KW - IR ellipsometry KW - quartz crystal microbalance Y1 - 2017 U6 - https://doi.org/10.1016/j.electacta.2017.01.080 SN - 0013-4686 SN - 1873-3859 VL - 229 SP - 325 EP - 333 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Zacharias, Michael A1 - Chen, Xuhui A1 - Wagner, Stefan T1 - Attenuation of TeV gamma-rays by the starlight photon field of the host galaxy JF - Monthly notices of the Royal Astronomical Society N2 - The absorption of TeV gamma-ray photons produced in relativistic jets by surrounding soft photon fields is a long-standing problem of jet physics. In some cases, the most likely emission site close to the central black hole is ruled out because of the high opacity caused by strong optical and infrared photon sources, such as the broad-line region. Mostly neglected for jet modelling is the absorption of gamma-rays in the starlight photon field of the host galaxy. Analysing the absorption for arbitrary locations and observation angles of the gamma-ray emission site within the host galaxy, we find that the distance to the galaxy centre, the observation angle, and the distribution of starlight in the galaxy are crucial for the amount of absorption. We derive the absorption value for a sample of 20 TeV-detected blazars with a redshift z(r) < 0.2. The absorption value of the gamma-ray emission located in the galaxy centre may be as high as 20 per cent, with an average value of 6 per cent. This is important in order to determine the intrinsic blazar parameters. We see no significant trends in our sample between the degree of absorption and host properties, such as starlight emissivity, galactic size, half-light radius, and redshift. While the uncertainty of the spectral properties of the extragalactic background light exceeds the effect of absorption by stellar light from the host galaxy in distant objects, the latter is a dominant effect in nearby sources. It may also be revealed in a differential comparison of sources with similar redshifts. KW - opacity KW - radiation mechanisms: non-thermal KW - galaxies: active KW - gamma-rays: galaxies Y1 - 2016 U6 - https://doi.org/10.1093/mnras/stw3032 SN - 0035-8711 SN - 1365-2966 VL - 465 IS - 3 SP - 3767 EP - 3774 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Anielski, Alexander A1 - Barbosa Pfannes, Eva Katharina A1 - Beta, Carsten T1 - Adaptive microfluidic gradient generator for quantitative chemotaxis experiments JF - Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques N2 - Chemotactic motion in a chemical gradient is an essential cellular function that controls many processes in the living world. For a better understanding and more detailed modelling of the underlying mechanisms of chemotaxis, quantitative investigations in controlled environments are needed. We developed a setup that allows us to separately address the dependencies of the chemotactic motion on the average background concentration and on the gradient steepness of the chemoattractant. In particular, both the background concentration and the gradient steepness can be kept constant at the position of the cell while it moves along in the gradient direction. This is achieved by generating a well-defined chemoattractant gradient using flow photolysis. In this approach, the chemoattractant is released by a light-induced reaction from a caged precursor in a microfluidic flow chamber upstream of the cell. The flow photolysis approach is combined with an automated real-time cell tracker that determines changes in the cell position and triggers movement of the microscope stage such that the cell motion is compensated and the cell remains at the same position in the gradient profile. The gradient profile can be either determined experimentally using a caged fluorescent dye or may be alternatively determined by numerical solutions of the corresponding physical model. To demonstrate the function of this adaptive microfluidic gradient generator, we compare the chemotactic motion of Dictyostelium discoideum cells in a static gradient and in a gradient that adapts to the position of the moving cell. Published by AIP Publishing. Y1 - 2017 U6 - https://doi.org/10.1063/1.4978535 SN - 0034-6748 SN - 1089-7623 VL - 88 PB - American Institute of Physics CY - Melville ER - TY - GEN A1 - Metzler, Ralf T1 - Gaussianity Fair BT - the Riddle of Anomalous yet Non-Gaussian Diffusion T2 - Biophysical journal Y1 - 2017 U6 - https://doi.org/10.1016/j.bpj.2016.12.019 SN - 0006-3495 SN - 1542-0086 VL - 112 IS - 3 SP - 413 EP - 415 PB - Cell Press CY - Cambridge ER - TY - GEN A1 - Metzler, Ralf T1 - Anomalous Diffusion in Membranes and the Cytoplasm of Biological Cells T2 - Biophysical journal Y1 - 2017 U6 - https://doi.org/10.1016/j.bpj.2016.11.2577 SN - 0006-3495 SN - 1542-0086 VL - 112 IS - 3 SP - 476A EP - 476A PB - Cell Press CY - Cambridge ER - TY - JOUR A1 - Ramachandran, Varsha A1 - Das, S. R. A1 - Tej, A. A1 - Vig, S. A1 - Ghosh, S. K. A1 - Ojha, D. K. T1 - Radio and infrared study of the star-forming region IRAS 20286+4105 JF - Monthly notices of the Royal Astronomical Society N2 - In this paper, we present a multi wavelength investigation of the star-forming complex IRAS 20286+4105, located in the Cygnus X region. Near-infrared K-band data are used to revisit the cluster/stellar group identified in previous studies. Radio continuum observations at 610 and 1280 MHz show the presence of a H II region possibly powered by a star of spectral type B0-B0.5. The cometary morphology of the ionized region is explained by invoking the bowshock model, where the likely association with a nearby supernova remnant is also explored. A compact radio knot with a non-thermal spectral index is detected towards the centre of the cloud. Mid-infrared data from the Spitzer Legacy Survey of the Cygnus X region show the presence of six Class I young stellar objects inside the cloud. Thermal dust emission in this complex is modelled using Herschel far-infrared data to generate dust temperature and column density maps. Herschel images also show the presence of two clumps in this region, the masses of which are estimated to be similar to 175 and 30 M-circle dot. The mass-radius relation and the surface density of the clumps mean that they do not qualify as massive star-forming sites. An overall picture of a runaway star ionizing the cloud and a triggered population of intermediatemass, Class I sources located towards the cloud centre emerges from this multiwavelength study. Variation in the dust emissivity spectral index is shown to exist in this region and is seen to have an inverse relation with the dust temperature. KW - stars: formation KW - H II regions KW - ISM: individual objects: IRAS 20286+4105 KW - radio continuum: ISM Y1 - 2016 U6 - https://doi.org/10.1093/mnras/stw2906 SN - 0035-8711 SN - 1365-2966 VL - 465 IS - 4 SP - 4753 EP - 4771 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Koopman, Wouter-Willem Adriaan A1 - Natali, Marco A1 - Donati, Giovanni P. A1 - Muccini, Michele A1 - Toffanin, Stefano T1 - Charge-exciton interaction rate in organic field-effect transistors by means of transient photoluminescence electromodulated spectroscopy JF - ACS photonics N2 - Organic light-emitting transistors (OLETs) offer a huge potential for the design of highly integrated multifunctional optoelectronic systems and of intense nano scale light sources, such as the long-searched-for electrically pumped organic laser. In order to fulfill these promises, the efficiency and brightness of the current state-of-the-art devices have to be increased significantly. The dominating quenching process limiting the external quantum efficiency in OLETs is charge-exciton interaction. A comprehensive understanding of this quenching process is therefore of paramount importance. The present article reports a systematic investigation of charge-exciton interaction in organic transistors employing time resolved photoluminescence electro-modulation (PLEM) spectroscopy on the picosecond time scale. The results show that the injected charges reduce the exciton radiative recombination in two ways: (i) charges may prevent the generation of excitons and (ii) charges activate a further nonradiative channel for the exciton decay. Moreover, the transient PLEM measurements clearly reveal that not only trapped charges, as already reported in literature, but rather the entire injected charge density contributes to the quenching of the exciton population. KW - photoluminescence quenching KW - charge density KW - exciton dynamics KW - organic KW - field-effect transistor KW - light emission KW - optical spectroscopy Y1 - 2017 U6 - https://doi.org/10.1021/acsphotonics.6b00573 SN - 2330-4022 VL - 4 IS - 2 SP - 282 EP - 291 PB - American Chemical Society CY - Washington, DC ER - TY - JOUR A1 - Sun, Ning-Chen A1 - de Grijs, Richard A1 - Subramanian, Smitha A1 - Cioni, Maria-Rosa L. A1 - Rubele, Stefano A1 - Bekki, Kenji A1 - Ivanov, Valentin D. A1 - Piatti, Andrés E. A1 - Ripepi, Vincenzo T1 - The VMC Survey. XXII. Hierarchical star formation in the 30 Doradus-N158-N159-N160 star-forming complex JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - We study the hierarchical stellar structures in a similar to 1.5 deg(2) area covering the 30. Doradus-N158-N159-N160 starforming complex with the VISTA Survey of. Magellanic Clouds. Based on the young upper main-sequence stars, we find that the surface densities cover a wide range of values, from log(Sigma.pc(2))less than or similar to -2.0 to log(Sigma. pc(2)) greater than or similar to 0.0. Their distributions are highly non-uniform, showing groups that frequently have subgroups inside. The sizes of the stellar groups do not exhibit characteristic values, and range continuously from several parsecs to more than 100. pc; the cumulative size distribution can be well described by a single power law, with the power-law index indicating a projected fractal dimension D-2 = 1.6 +/- 0.3. We suggest that the phenomena revealed here support a scenario of hierarchical star formation. Comparisons with other star-forming regions and galaxies are also discussed. KW - galaxies: clusters: general KW - infrared: stars KW - Magellanic Clouds KW - stars: formation Y1 - 2017 U6 - https://doi.org/10.3847/1538-4357/835/2/171 SN - 0004-637X SN - 1538-4357 VL - 835 IS - 2 PB - Institute of Physics Publ. CY - Bristol ER - TY - JOUR A1 - Warren, Donald C. A1 - Ellison, Donald C. A1 - Barkov, Maxim V. A1 - Nagataki, Shigehiro T1 - Nonlinear Particle Acceleration and Thermal Particles in GRB Afterglows JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - The standard model for GRB afterglow emission treats the accelerated electron population as a simple power law, N(E) proportional to E-p for p greater than or similar to 2. However, in standard Fermi shock acceleration, a substantial fraction of the swept-up particles do not enter the acceleration process at all. Additionally, if acceleration is efficient, then the nonlinear back-reaction of accelerated particles on the shock structure modifies the shape of the nonthermal tail of the particle spectra. Both of these modifications to the standard synchrotron afterglow impact the luminosity, spectra, and temporal variation of the afterglow. To examine the effects of including thermal particles and nonlinear particle acceleration on afterglow emission, we follow a hydrodynamical model for an afterglow jet and simulate acceleration at numerous points during the evolution. When thermal particles are included, we find that the electron population is at no time well fitted by a single power law, though the highest-energy electrons are; if the acceleration is efficient, then the power-law region is even smaller. Our model predicts hard-soft-hard spectral evolution at X-ray energies, as well as an uncoupled X-ray and optical light curve. Additionally, we show that including emission from thermal particles has drastic effects (increases by factors of 100 and 30, respectively) on the observed flux at optical and GeV energies. This enhancement of GeV emission makes afterglow detections by future gamma-ray observatories, such as CTA, very likely. KW - acceleration of particles KW - cosmic rays KW - gamma-ray burst: general KW - shock waves KW - turbulence Y1 - 2017 U6 - https://doi.org/10.3847/1538-4357/aa56c3 SN - 0004-637X SN - 1538-4357 VL - 835 IS - 2 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Archambault, S. A1 - Archer, A. A1 - Benbow, W. A1 - Buchovecky, M. A1 - Bugaev, V. A1 - Cerruti, M. A1 - Connolly, M. P. A1 - Cui, W. A1 - Falcone, A. A1 - Alonso, M. Fernandez A1 - Finley, J. P. A1 - Fleischhack, H. A1 - Fortson, L. A1 - Furniss, A. A1 - Griffin, S. A1 - Hutten, M. A1 - Hervet, O. A1 - Holder, J. A1 - Humensky, T. B. A1 - Johnson, C. A. A1 - Kaaret, P. A1 - Kar, P. A1 - Kieda, D. A1 - Krause, M. A1 - Krennrich, F. A1 - Lang, M. J. A1 - Lin, T. T. Y. A1 - Maier, G. A1 - McArthur, S. A1 - Moriarty, P. A1 - Nieto, D. A1 - Ong, R. A. A1 - Otte, A. N. A1 - Pohl, M. A1 - Popkow, A. A1 - Pueschel, Elisa A1 - Quinn, J. A1 - Ragan, K. A1 - Reynolds, P. T. A1 - Richards, G. T. A1 - Roache, E. A1 - Rovero, A. C. A1 - Sadeh, I. A1 - Shahinyan, K. A1 - Staszak, D. A1 - Telezhinsky, Igor O. A1 - Tyler, J. A1 - Wakely, S. P. A1 - Weinstein, A. A1 - Weisgarber, T. A1 - Wilcox, P. A1 - Wilhelm, Alina A1 - Williams, D. A. A1 - Zitzer, B. T1 - Search for Magnetically Broadened Cascade Emission from Blazars with VERITAS JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - We present a search for magnetically broadened gamma-ray emission around active galactic nuclei (AGNs), using VERITAS observations of seven hard-spectrum blazars. A cascade process occurs when multi-TeV gamma-rays from an AGN interact with extragalactic background light (EBL) photons to produce electron-positron pairs, which then interact with cosmic microwave background photons via inverse-Compton scattering to produce gamma-rays. Due to the deflection of the electron- positron pairs, a non-zero intergalactic magnetic field (IGMF) would potentially produce detectable effects on the angular distribution of the cascade emission. In particular, an angular broadening compared to the unscattered emission could occur. Through non-detection of angularly broadened emission from 1ES 1218 vertical bar 304, the source with the largest predicted cascade fraction, we exclude a range of IGMF strengths around 10(-14) G at the 95% confidence level. The extent of the exclusion range varies with the assumptions made about the intrinsic spectrum of 1ES. 1218+304 and the EBL model used in the simulation of the cascade process. All of the sources are used to set limits on the flux due to extended emission. KW - BL Lacertae objects: general KW - galaxies: active KW - gamma rays: galaxies KW - magnetic fields Y1 - 2017 U6 - https://doi.org/10.3847/1538-4357/835/2/288 SN - 0004-637X SN - 1538-4357 VL - 835 IS - 2 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Liu, Lin A1 - Cherstvy, Andrey G. A1 - Metzler, Ralf T1 - Facilitated Diffusion of Transcription Factor Proteins with Anomalous Bulk Diffusion JF - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry N2 - What are the physical laws of the diffusive search of proteins for their specific binding sites on DNA in the presence of the macromolecular crowding in cells? We performed extensive computer simulations to elucidate the protein target search on DNA. The novel feature is the viscoelastic non-Brownian protein bulk diffusion recently observed experimentally. We examine the influence of the protein-DNA binding affinity and the anomalous diffusion exponent on the target search time. In all cases an optimal search time is found. The relative contribution of intermittent three-dimensional bulk diffusion and one-dimensional sliding of proteins along the DNA is quantified. Our results are discussed in the light of recent single molecule tracking experiments, aiming at a better understanding of the influence of anomalous kinetics of proteins on the facilitated diffusion mechanism. Y1 - 2017 U6 - https://doi.org/10.1021/acs.jpcb.6b12413 SN - 1520-6106 VL - 121 SP - 1284 EP - 1289 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Almeida, Leonardo A. A1 - Sana, H. A1 - Taylor, W. A1 - Barbá, Rodolfo A1 - Bonanos, Alceste Z. A1 - Crowther, Paul A1 - Damineli, Augusto A1 - de Koter, A. A1 - de Mink, Selma E. A1 - Evans, C. J. A1 - Gieles, Mark A1 - Grin, Nathan J. A1 - Hénault-Brunet, V. A1 - Langer, Norbert A1 - Lennon, D. A1 - Lockwood, Sean A1 - Maíz Apellániz, Jesús A1 - Moffat, A. F. J. A1 - Neijssel, C. A1 - Norman, C. A1 - Ramírez-Agudelo, O. H. A1 - Richardson, N. D. A1 - Schootemeijer, Abel A1 - Shenar, Tomer A1 - Soszyński, Igor A1 - Tramper, Frank A1 - Vink, J. S. T1 - The tarantula massive binary monitoring BT - I. Observational campaign and OB-type spectroscopic binaries JF - Astronomy and astrophysics : an international weekly journal N2 - Context: Massive binaries play a crucial role in the Universe. Knowing the distributions of their orbital parameters is important for a wide range of topics from stellar feedback to binary evolution channels and from the distribution of supernova types to gravitational wave progenitors, yet no direct measurements exist outside the Milky Way. Aims: The Tarantula Massive Binary Monitoring project was designed to help fill this gap by obtaining multi-epoch radial velocity (RV) monitoring of 102 massive binaries in the 30 Doradus region. Methods: In this paper we analyze 32 FLAMES/GIRAFFE observations of 93 O- and 7 B-type binaries. We performed a Fourier analysis and obtained orbital solutions for 82 systems: 51 single-lined (SB1) and 31 double-lined (SB2) spectroscopic binaries. Results: Overall, the binary fraction and orbital properties across the 30 Doradus region are found to be similar to existing Galactic samples. This indicates that within these domains environmental effects are of second order in shaping the properties of massive binary systems. A small difference is found in the distribution of orbital periods, which is slightly flatter (in log space) in 30 Doradus than in the Galaxy, although this may be compatible within error estimates and differences in the fitting methodology. Also, orbital periods in 30 Doradus can be as short as 1.1 d, somewhat shorter than seen in Galactic samples. Equal mass binaries (q> 0.95) in 30 Doradus are all found outside NGC 2070, the central association that surrounds R136a, the very young and massive cluster at 30 Doradus’s core. Most of the differences, albeit small, are compatible with expectations from binary evolution. One outstanding exception, however, is the fact that earlier spectral types (O2–O7) tend to have shorter orbital periods than later spectral types (O9.2–O9.7). Conclusions: Our results point to a relative universality of the incidence rate of massive binaries and their orbital properties in the metallicity range from solar (Z⊙) to about half solar. This provides the first direct constraints on massive binary properties in massive star-forming galaxies at the Universe’s peak of star formation at redshifts z ~ 1 to 2 which are estimated to have Z ~ 0.5 Z⊙. KW - stars: early-type KW - stars: massive KW - binaries: spectroscopic KW - binaries: close Y1 - 2017 U6 - https://doi.org/10.1051/0004-6361/201629844 SN - 1432-0746 VL - 598 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Gorobtsov, O. Yu. A1 - Mercurio, G. A1 - Brenner, G. A1 - Lorenz, Ulf A1 - Gerasimova, N. A1 - Kurta, R. P. A1 - Hieke, F. A1 - Skopintsev, P. A1 - Zaluzhnyy, I. A1 - Lazarev, S. A1 - Dzhigaev, D. A1 - Rose, M. A1 - Singer, A. A1 - Wurth, W. A1 - Vartanyants, I. A. T1 - Statistical properties of a free-electron laser revealed by Hanbury Brown-Twiss interferometry JF - Physical review : A, Atomic, molecular, and optical physics N2 - We present a comprehensive experimental analysis of statistical properties of the self-amplified spontaneous emission free-electron laser (FEL) FLASH by means of Hanbury Brown and Twiss interferometry. The experiments were performed at FEL wavelengths of 5.5, 13.4, and 20.8 nm. We determined the second-order intensity correlation function for all wavelengths and different operation conditions of FLASH. In all experiments a high degree of spatial coherence (above 50%) was obtained. Our analysis performed in spatial and spectral domains provided us with the independent measurements of an average pulse duration of the FEL that were below 60 fs. To explain the complicated behavior of the second-order intensity correlation function we developed an advanced theoretical model that includes the presence of multiple beams and external positional jitter of the FEL pulses. By this analysis we determined that in one of the experiments external positional jitter was about 25% of the beam size. We envision that methods developed in our study will be used widely for analysis and diagnostics of FEL radiation. Y1 - 2017 U6 - https://doi.org/10.1103/PhysRevA.95.023843 SN - 2469-9926 SN - 2469-9934 VL - 95 IS - 2 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Godec, Aljaž A1 - Metzler, Ralf T1 - First passage time statistics for two-channel diffusion JF - Journal of physics : A, Mathematical and theoretical N2 - We present rigorous results for the mean first passage time and first passage time statistics for two-channel Markov additive diffusion in a 3-dimensional spherical domain. Inspired by biophysical examples we assume that the particle can only recognise the target in one of the modes, which is shown to effect a non-trivial first passage behaviour. We also address the scenario of intermittent immobilisation. In both cases we prove that despite the perfectly non-recurrent motion of two-channel Markov additive diffusion in 3 dimensions the first passage statistics at long times do not display Poisson-like behaviour if none of the phases has a vanishing diffusion coefficient. This stands in stark contrast to the standard (one-channel) Markov diffusion counterpart. We also discuss the relevance of our results in the context of cellular signalling. KW - first passage time KW - Markov additive processes KW - Fokker-Planck equation KW - random search processes KW - coupled initial boundary value problem KW - cellular signalling KW - asymptotic analysis Y1 - 2017 U6 - https://doi.org/10.1088/1751-8121/aa5204 SN - 1751-8113 SN - 1751-8121 VL - 50 IS - 8 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Goychuk, Igor T1 - Quantum ergodicity breaking in semi-classical electron transfer dynamics JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - Can the statistical properties of single-electron transfer events be correctly predicted within a common equilibrium ensemble description? This fundamental in nanoworld question of ergodic behavior is scrutinized within a very basic semi-classical curve-crossing problem. It is shown that in the limit of non-adiabatic electron transfer (weak tunneling) well-described by the Marcus-Levich-Dogonadze (MLD) rate the answer is yes. However, in the limit of the so-called solvent-controlled adiabatic electron transfer, a profound breaking of ergodicity occurs. Namely, a common description based on the ensemble reduced density matrix with an initial equilibrium distribution of the reaction coordinate is not able to reproduce the statistics of single-trajectory events in this seemingly classical regime. For sufficiently large activation barriers, the ensemble survival probability in a state remains nearly exponential with the inverse rate given by the sum of the adiabatic curve crossing (Kramers) time and the inverse MLD rate. In contrast, near to the adiabatic regime, the single-electron survival probability is clearly non-exponential, even though it possesses an exponential tail which agrees well with the ensemble description. Initially, it is well described by a Mittag-Leffler distribution with a fractional rate. Paradoxically, the mean transfer time in this classical on the ensemble level regime is well described by the inverse of the nonadiabatic quantum tunneling rate on a single particle level. An analytical theory is developed which perfectly agrees with stochastic simulations and explains our findings. Y1 - 2016 U6 - https://doi.org/10.1039/c6cp07206b SN - 1463-9076 SN - 1463-9084 VL - 19 SP - 3056 EP - 3066 PB - Royal Society of Chemistry CY - Cambridge ER -