Refine
Has Fulltext
- no (203)
Year of publication
- 2016 (203) (remove)
Document Type
- Article (203) (remove)
Is part of the Bibliography
- yes (203)
Keywords
- Magellanic Clouds (8)
- Sun: magnetic fields (6)
- intergalactic medium (6)
- methods: data analysis (6)
- techniques: spectroscopic (6)
- galaxies: formation (5)
- stars: Wolf-Rayet (5)
- stars: atmospheres (5)
- turbulence (5)
- X-rays: binaries (4)
- stars: winds, outflows (4)
- techniques: polarimetric (4)
- Sun: photosphere (3)
- acceleration of particles (3)
- diffusion (3)
- galaxies: evolution (3)
- instabilities (3)
- methods: observational (3)
- plasmas (3)
- quasars: absorption lines (3)
- radiation mechanisms: non-thermal (3)
- stars: evolution (3)
- stars: magnetic field (3)
- stars: massive (3)
- surveys (3)
- BL Lacertae objects: general (2)
- Brownian motion (2)
- Debye screening (2)
- Electrophoretic deposition (2)
- Galaxy: center (2)
- Sun: corona (2)
- Sun: flares (2)
- Synchronization (2)
- Transformation toughening (2)
- X-rays: stars (2)
- anomalous diffusion (2)
- binaries: general (2)
- climate change (2)
- critical phenomena (2)
- dust, extinction (2)
- electromagnetic radiation (2)
- electrostatic interactions (2)
- galaxies: active (2)
- gamma rays: galaxies (2)
- gamma rays: general (2)
- gamma-rays: general (2)
- general relativity (2)
- globular clusters: individual: NGC 6397 (2)
- gravity (2)
- history and philosophy of astronomy (2)
- hydrodynamics (2)
- laser pulses (2)
- linearized gravity (2)
- magnetohydrodynamics (MHD) (2)
- polyelectrolyte adsorption (2)
- pp-wave solutions (2)
- pulsars: general (2)
- relativistic processes (2)
- stars: AGB and post-AGB (2)
- stars: abundances (2)
- stars: early-type (2)
- stars: variables: Cepheids (2)
- stars: variables: general (2)
- sunspots (2)
- techniques: imaging spectroscopy (2)
- techniques: photometric (2)
- vulnerability (2)
- waves (2)
- (Z)-isomer (1)
- 3-D diffusion simulation (1)
- Ageing (1)
- Anomalous diffusion (1)
- BL Lacertae objects: individual: Mrk 421 (1)
- BL Lacertae objects: individual: Mrk 501 (1)
- Bastille Day geomagnetic storm (1)
- Biomechanics (1)
- Blue stars (1)
- Bose-Einstein condensate (1)
- Bose-Hubbard model (1)
- CAL-72 osteoblasts (1)
- CH center dot center dot center dot F hydrogen bonds (1)
- Cartilage tissue engineering (1)
- Classroom management (1)
- Crack deflection (1)
- Cycle-averaged tilt angle (1)
- Dehydrothermal cross linking (1)
- Diffusion (1)
- Dilational rheology (1)
- Donor materials (1)
- Drop profile analysis tensiometry (1)
- Electronic and spintronic devices (1)
- FRAP (1)
- Gelatin-PLGA Scaffold (1)
- HII regions (1)
- Half-center oscillator (1)
- Hodgkin-Huxley model (1)
- Hydraulic models (1)
- Hydraulic networks (1)
- Hydroclimate (1)
- ISM: abundances (1)
- ISM: clouds (1)
- ISM: molecules (1)
- ISM: supernova remnants (1)
- Information coding (1)
- Infrared observations (1)
- Inhibitory neurons (1)
- Instructional quality (1)
- Josephson junction (1)
- Kuramoto model (1)
- L-929 fibroblasts (1)
- Layer-by-layer (1)
- Levy flights (1)
- Local Group (1)
- Low voltage losses (1)
- MHD (1)
- Maximum entropy method (1)
- Mediation-model (1)
- Mixed adsorption layers (1)
- Multilayer (1)
- Neural network (1)
- Noether theorem (1)
- Non-linear analysis (1)
- Odor discrimination (1)
- Olfactory system (1)
- Outflows (1)
- Pedagogical professional knowledge (1)
- Photosensitive azobenzene containing polyamines (1)
- Photosensitive brushes (1)
- Pipe networks (1)
- Poly-epsilon-caprolactone (1)
- Polymer-dispersed liquid crystal (1)
- Polymer/surfactant interaction (1)
- Porous scaffold (1)
- Post-inhibitory rebound (1)
- Probability (1)
- Professional knowledge (1)
- Protein (1)
- Radiative transfer (1)
- Radiocarbon (1)
- Rat model (1)
- Rayet (1)
- Reactive foaming (1)
- Release (1)
- Scher-Montroll transport (1)
- Semiconductors (1)
- Spectroscopy (1)
- Spike sequences (1)
- Stalagmite (1)
- Stars: atmospheres early type (1)
- Stars: mass-loss (1)
- Stars: winds (1)
- Stellar winds (1)
- Strontium (1)
- Sublimation with good yield (1)
- Sun: activity (1)
- Sun: atmosphere (1)
- Sun: chromosphere (1)
- Sun: coronal mass ejections (CMEs) (1)
- Sun: filaments (1)
- Sun: filaments, pominences (1)
- Sun: sunspots (1)
- Talbot-Lau interferometry (1)
- Thermodynamics of adsorption (1)
- Tilt angles (1)
- Trace elements (1)
- Tropics (1)
- Van Allen Probes (1)
- Venus, surface (1)
- Water distribution systems (1)
- Water/air interface (1)
- X-ray emission spectra (1)
- X-ray mu CT (1)
- X-ray refraction (1)
- X-ray scattering (1)
- XMCD (1)
- Yttria stabilized zirconia (1)
- Yttria stabilized zirconia multilayers (1)
- accretion, accretion disks (1)
- active transport (1)
- advective-diffusive codes (1)
- anti-Stokes resonant x-ray raman scattering (1)
- astrobiology (1)
- astrochemistry (1)
- astroparticle physics (1)
- atomic data (1)
- atomtronics (1)
- azobenzene (1)
- azobenzene containing surfactants (1)
- bacterial swimming (1)
- bi-photons (1)
- bifurcation (1)
- binaries: close (1)
- binaries: symbiotic (1)
- binaries: visual (1)
- black hole physics (1)
- blue stragglers (1)
- brushes (1)
- cell wall deficient mutant (1)
- chaos (1)
- chaotic neural dynamics (1)
- charge accumulation (1)
- charge carrier transport (1)
- charge transfer (1)
- coherence (1)
- collective dynamics (1)
- comb-like model (1)
- conduction (1)
- conductivity (1)
- conservation laws (1)
- coronal mass ejections (CMEs) (1)
- cortical network models (1)
- cortical oscillations (1)
- cosmic ray theory (1)
- cosmic rays (1)
- cosmology: observations (1)
- coupled oscillators (1)
- crosslinking (1)
- crowded fluids (1)
- crystalline ordering (1)
- current voltage analysis (1)
- damage (1)
- dark matter theory (1)
- dielectric properties (1)
- distance scale (1)
- diurnal rhythm (1)
- domain memory in polymer brushes (1)
- elastomers (1)
- electric field noise (1)
- electron number density (1)
- entanglement (1)
- excited state selectivity (1)
- extraterrestrial intelligence (1)
- femtosecond slicing (1)
- ferroelectric polymer (1)
- field-effect-transistor (1)
- films (1)
- first arrival (1)
- first passage (1)
- first passage process (1)
- fluctuation dissipation (1)
- fluctuation-dissipation theorem (1)
- food security (1)
- free electron lasers (1)
- free shear layers (1)
- galaxies: ISM (1)
- galaxies: abundances (1)
- galaxies: clusters: intracluster medium (1)
- galaxies: halos (1)
- galaxies: high-redshift (1)
- galaxies: individual: 1ES 1741+196=VER J1744+195 (1)
- galaxies: individual: SMC (1)
- galaxies: jets (1)
- galaxies: star clusters: general (1)
- generalised Langevin equation (1)
- genomic DNA conformation (1)
- global jets (1)
- globular clusters: individual: (SMASH 1) (1)
- globular clusters: individual: 47 Tucanae (1)
- gradients (1)
- group field theory (1)
- halo (1)
- heat diffusion (1)
- helical magnetic fields (1)
- hierarchical modular networks (1)
- infrared: galaxies (1)
- infrared: stars (1)
- inner magnetosphere (1)
- inner radiation zone and slot region (1)
- instability control (1)
- integrability (1)
- intrinsic neuronal diversity (1)
- ion trap (1)
- ionic conductivity (1)
- ionic liquids (1)
- ionogels (1)
- ionosphere (1)
- irregular firing activity (1)
- kinetic instabilities (1)
- kink instability (1)
- light driven reversible change of surface topography and thickness (1)
- line: identification (1)
- line: profiles (1)
- linear response theory (1)
- liquid crystal alignment (1)
- magnetic fields (1)
- mean squared displacement (1)
- mechanical properties (1)
- meteorological extremes (1)
- microstructure (1)
- molecular doping (1)
- morphology (1)
- mu CT imaging (1)
- nanostructures (1)
- neural networks (1)
- noise in biochemical signalling (1)
- non-local field theory (1)
- nonlinear microscopy (1)
- numerical schemes (1)
- optical manipulation (1)
- optical pump (1)
- organic semiconductors (1)
- organic solar cells (1)
- orientation of azobenzenes in polymer brushes (1)
- oscillator populations (1)
- outflows (1)
- particle physics - cosmology connection (1)
- particle-in-cell simulations (1)
- perturbation theory (1)
- phase grating (1)
- phase separation (1)
- photocontrol (1)
- photosensitive brushes (1)
- photosensitive surfactants (1)
- photosynthesis (1)
- planetary nebulae: general (1)
- planets and satellites: fundamental parameters (1)
- planets and satellites: individual: Jupiter (1)
- plasmaspheric hiss (1)
- predator-prey model (1)
- probability density function (1)
- proper motions (1)
- pulsars: individual (PSR J1023+0038) (1)
- pump-probe (1)
- quantum eraser (1)
- quantum optics (1)
- quasars: general (1)
- quasars: individual (SDSS J142253.31-000149) (1)
- quasars: individual (SDSS J213748+001220, SDSS J215200+062516) (1)
- quasi-periodic oscillation (1)
- radiative transfer (1)
- random search process (1)
- random walks (1)
- recurrence (1)
- relativistic jets (1)
- remanent polarisation (1)
- resonant inelastic x-ray scattering (1)
- self-sustained activity (1)
- semiconducting polymers (1)
- sensors and actuators (1)
- single-cell analysis (1)
- solar wind (1)
- stars: Wolf (1)
- stars: emission-line, Be (1)
- stars: formation (1)
- stars: individual ( KIC 8462852) (1)
- stars: individual (LS I+61 degrees 303, VER J0240+612) (1)
- stars: individual (gamma Cassiopeiae) (1)
- stars: individual (zeta Oph, BD+43 degrees 3654) (1)
- stars: individual (zetaPup) (1)
- stars: individual: CPD-57 degrees 3509 (1)
- stars: individual: RE 0457-281 (1)
- stars: individual: RE 0503-289 (1)
- stars: individual: WR 102c (1)
- stars: individual: WR 134 (1)
- stars: individual: WR 137 (1)
- stars: individual: WR 138 (1)
- stars: individual: WR 6 (1)
- stars: jets (1)
- stars: kinematics and dynamics (1)
- stars: mass-loss (1)
- stars: neutron (1)
- stars: oscillations (1)
- stars: winds (1)
- stochastic models (1)
- stochastic processes (1)
- sudden stratosphere warming (1)
- supergiants (1)
- supernovae: individual (G0.9+0.1) (1)
- supersymmetry and cosmology (1)
- surface deformation (1)
- synchronization (1)
- synchrotron imaging (1)
- techniques: image processing (1)
- techniques: radial velocities (1)
- teleconnections (1)
- telescopes (1)
- tracking (1)
- trade shocks (1)
- transport (1)
- tropical cyclones (1)
- tunneling (1)
- turbulence control (1)
- ultracold atoms (1)
- ultrafast X-ray diffraction (1)
- ultrafast photochemistry (1)
- up-down states (1)
- virtual observatory tools (1)
- visibility (1)
- white dwarfs (1)
Institute
- Institut für Physik und Astronomie (203) (remove)
Context. For the spectral analysis of high-resolution and high signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims. New Kr IV-VII oscillator strengths for a large number of lines enable us to construct more detailed model atoms for our NLTE model-atmosphere calculations. This enables us to search for additional Kr lines in observed spectra and to improve Kr abundance determinations. Methods. We calculated Kr IV-VII oscillator strengths to consider radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Kr lines that are exhibited in high-resolution and high S/N ultraviolet (UV) observations of the hot white dwarf RE 0503-289. Results. We reanalyzed the effective temperature and surface gravity and determined T-eff = 70 000 +/- 2000 K and log (g/cm s(-2)) = 7.5 +/- 0.1. We newly identified ten Kr V lines and one Kr vi line in the spectrum of RE 0503-289. We measured a Kr abundance of 3.3 +/- 0.3 (logarithmic mass fraction). We discovered that the interstellar absorption toward RE 0503-289 has a multi-velocity structure within a radial-velocity interval of -40 km s(-1) < upsilon(rad) < +18 km s(-1). Conclusions. Reliable measurements and calculations of atomic data are a prerequisite for state-of-the-art NLTE stellar-atmosphere modeling. Observed Kr V-VII line profiles in the UV spectrum of the white dwarf RE 0503-289 were simultaneously well reproduced with our newly calculated oscillator strengths.
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.
We investigate the ensemble and time averaged mean squared displacements for particle diffusion in a simple model for disordered media by assuming that the local diffusivity is both fluctuating in time and has a deterministic average growth or decay in time. In this study we compare computer simulations of the stochastic Langevin equation for this random diffusion process with analytical results. We explore the regimes of normal Brownian motion as well as anomalous diffusion in the sub- and superdiffusive regimes. We also consider effects of the inertial term on the particle motion. The investigation of the resulting diffusion is performed for unconfined and confined motion.
We study the adsorption–desorption transition of polyelectrolyte chains onto planar, cylindrical and spherical surfaces with arbitrarily high surface charge densities by massive Monte Carlo computer simulations. We examine in detail how the well known scaling relations for the threshold transition—demarcating the adsorbed and desorbed domains of a polyelectrolyte near weakly charged surfaces—are altered for highly charged interfaces. In virtue of high surface potentials and large surface charge densities, the Debye–Hückel approximation is often not feasible and the nonlinear Poisson–Boltzmann approach should be implemented. At low salt conditions, for instance, the electrostatic potential from the nonlinear Poisson–Boltzmann equation is smaller than the Debye–Hückel result, such that the required critical surface charge density for polyelectrolyte adsorption σc increases. The nonlinear relation between the surface charge density and electrostatic potential leads to a sharply increasing critical surface charge density with growing ionic strength, imposing an additional limit to the critical salt concentration above which no polyelectrolyte adsorption occurs at all. We contrast our simulations findings with the known scaling results for weak critical polyelectrolyte adsorption onto oppositely charged surfaces for the three standard geometries. Finally, we discuss some applications of our results for some physical–chemical and biophysical systems.
During the summer of 2013, a 4-month spectroscopic campaign took place to observe the variabilities in three Wolf-Rayet stars. The spectroscopic data have been analysed for WR 134 (WN6b), to better understand its behaviour and long-term periodicity, which we interpret as arising from corotating interaction regions (CIRs) in the wind. By analysing the variability of the He ii lambda 5411 emission line, the previously identified period was refined to P = 2.255 +/- 0.008 (s.d.) d. The coherency time of the variability, which we associate with the lifetime of the CIRs in the wind, was deduced to be 40 +/- 6 d, or similar to 18 cycles, by cross-correlating the variability patterns as a function of time. When comparing the phased observational grey-scale difference images with theoretical grey-scales previously calculated from models including CIRs in an optically thin stellar wind, we find that two CIRs were likely present. A separation in longitude of Delta I center dot a parts per thousand integral 90A degrees was determined between the two CIRs and we suggest that the different maximum velocities that they reach indicate that they emerge from different latitudes. We have also been able to detect observational signatures of the CIRs in other spectral lines (C iv lambda lambda 5802,5812 and He i lambda 5876). Furthermore, a DAC was found to be present simultaneously with the CIR signatures detected in the He i lambda 5876 emission line which is consistent with the proposed geometry of the large-scale structures in the wind. Small-scale structures also show a presence in the wind, simultaneously with the larger scale structures, showing that they do in fact co-exist.
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.
Imaging changes in molecular geometries on their natural femtosecond timescale with sub-Angstrom spatial precision is one of the critical challenges in the chemical sciences, as the nuclear geometry changes determine the molecular reactivity. For photoexcited molecules, the nuclear dynamics determine the photoenergy conversion path and efficiency. Here we report a gas-phase electron diffraction experiment using megaelectronvolt (MeV) electrons, where we captured the rotational wavepacket dynamics of nonadiabatically laser-aligned nitrogen molecules. We achieved a combination of 100 fs root-mean-squared temporal resolution and sub-Angstrom (0.76 angstrom) spatial resolution that makes it possible to resolve the position of the nuclei within the molecule. In addition, the diffraction patterns reveal the angular distribution of the molecules, which changes from prolate (aligned) to oblate (anti-aligned) in 300 fs. Our results demonstrate a significant and promising step towards making atomically resolved movies of molecular reactions.
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.
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.