Refine
Year of publication
- 2016 (258) (remove)
Document Type
- Article (203)
- Doctoral Thesis (21)
- Postprint (18)
- Other (10)
- Review (4)
- Habilitation Thesis (2)
Is part of the Bibliography
- yes (258)
Keywords
- Magellanic Clouds (8)
- Sun: magnetic fields (6)
- intergalactic medium (6)
- methods: data analysis (6)
- stars: Wolf-Rayet (6)
- techniques: spectroscopic (6)
- galaxies: formation (5)
- stars: atmospheres (5)
- turbulence (5)
- X-rays: binaries (4)
- general relativity (4)
- stars: winds, outflows (4)
- techniques: polarimetric (4)
- Debye screening (3)
- Galaxy: center (3)
- Sun: photosphere (3)
- acceleration of particles (3)
- azobenzene (3)
- critical phenomena (3)
- diffusion (3)
- electromagnetic radiation (3)
- electrostatic interactions (3)
- galaxies: evolution (3)
- gravity (3)
- instabilities (3)
- laser pulses (3)
- linearized gravity (3)
- magnetohydrodynamics (MHD) (3)
- methods: observational (3)
- plasmas (3)
- polyelectrolyte adsorption (3)
- pp-wave solutions (3)
- quasars: absorption lines (3)
- radiation mechanisms: non-thermal (3)
- stars: evolution (3)
- stars: magnetic field (3)
- stars: massive (3)
- surveys (3)
- Anomalous diffusion (2)
- BL Lacertae objects: general (2)
- Brownian motion (2)
- Diffusion (2)
- Electronic and spintronic devices (2)
- Electrophoretic deposition (2)
- HII regions (2)
- Scher-Montroll transport (2)
- Semiconductors (2)
- Sun: corona (2)
- Sun: flares (2)
- Synchronization (2)
- Transformation toughening (2)
- X-rays: stars (2)
- anomalous diffusion (2)
- astrophysics (2)
- binaries: general (2)
- brushes (2)
- chaotic neural dynamics (2)
- climate change (2)
- cortical network models (2)
- cortical oscillations (2)
- dust, extinction (2)
- films (2)
- galaxies: active (2)
- gamma rays: galaxies (2)
- gamma rays: general (2)
- gamma-rays: general (2)
- genomic DNA conformation (2)
- global jets (2)
- globular clusters: individual: NGC 6397 (2)
- gradients (2)
- helical magnetic fields (2)
- hierarchical modular networks (2)
- history and philosophy of astronomy (2)
- hydrodynamics (2)
- hypersound (2)
- intrinsic neuronal diversity (2)
- irregular firing activity (2)
- kinetic instabilities (2)
- kink instability (2)
- optical manipulation (2)
- particle-in-cell simulations (2)
- photocontrol (2)
- photosensitive surfactants (2)
- pulsars: general (2)
- relativistic jets (2)
- relativistic processes (2)
- self-sustained activity (2)
- stars: AGB and post-AGB (2)
- stars: abundances (2)
- stars: early-type (2)
- stars: individual: WR 102c (2)
- stars: variables: Cepheids (2)
- stars: variables: general (2)
- sunspots (2)
- techniques: imaging spectroscopy (2)
- techniques: photometric (2)
- tracking (2)
- transport (2)
- ultrafast (2)
- up-down states (2)
- vulnerability (2)
- waves (2)
- (Z)-isomer (1)
- 3-D diffusion simulation (1)
- Ageing (1)
- Anharmonizität (1)
- Arctic atmosphere (1)
- Astrophysik (1)
- Azobenzene (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)
- Brillouin scattering (1)
- Brownian nanomachines (1)
- CAL-72 osteoblasts (1)
- CH center dot center dot center dot F hydrogen bonds (1)
- Cartilage tissue engineering (1)
- Chemokinematik der Milchstraße (1)
- Chromhexacarbonyl (1)
- Classroom management (1)
- Crack deflection (1)
- Cycle-averaged tilt angle (1)
- DNA methylation (1)
- DNA supercoiling (1)
- DNA-protein binding (1)
- Dehydrothermal cross linking (1)
- Dilational rheology (1)
- Dissertation (1)
- Donor materials (1)
- Drop profile analysis tensiometry (1)
- Eisenpentacarbonyl (1)
- Entstehung der Milchstraße (1)
- Evolution der Milchstraße (1)
- FRAP (1)
- Faltung von Proteinen (1)
- Galaxien (1)
- Galaxien bei hoher Rotverschiebung (1)
- Gelatin-PLGA Scaffold (1)
- Genregulation (1)
- Gold-Nanopartikel (1)
- Gravitationswellen (1)
- Half-center oscillator (1)
- Hodgkin-Huxley model (1)
- Hydraulic models (1)
- Hydraulic networks (1)
- Hydroclimate (1)
- ISM: Turbulence (1)
- ISM: Turbulenz (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)
- Integralfeldspektroskopie (1)
- Josephson junction (1)
- Kosmologie (1)
- Kuramoto model (1)
- L-929 fibroblasts (1)
- LOFAR (1)
- Layer-by-layer (1)
- Levy flights (1)
- Lipid bilayer (1)
- Local Group (1)
- Low voltage losses (1)
- MHD (1)
- Magnetohydrodynamik (1)
- Maximum entropy method (1)
- Mediation-model (1)
- Mikrometeorologie (1)
- Milky Way chemo-kinematics (1)
- Milky Way evolution (1)
- Milky Way formation (1)
- Mixed adsorption layers (1)
- Molecular crowding (1)
- Moleküldynamik (1)
- Multilayer (1)
- Neural network (1)
- Noether theorem (1)
- Non-Gaussian (1)
- Non-linear analysis (1)
- Odor discrimination (1)
- Olfactory system (1)
- Outflows (1)
- Pedagogical professional knowledge (1)
- Phononen (1)
- Phononenstreuung (1)
- Photodissoziation (1)
- Photoelektronen (1)
- Photosensitive azobenzene containing polyamines (1)
- Photosensitive brushes (1)
- Pipe networks (1)
- Plasmaphysik (1)
- Plasmonics (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)
- Protein crowding (1)
- Pseudodatensätze (1)
- Pump-Probe Spektroskopie (1)
- Quasare (1)
- RAVE Beobachtungskampagne (1)
- RAVE survey (1)
- Radiative transfer (1)
- Radioburst (1)
- Radiocarbon (1)
- Rat model (1)
- Rayet (1)
- Reactive foaming (1)
- Release (1)
- SEGUE Beobachtungskampagne (1)
- SEGUE survey (1)
- Scher-Montroll Transport (1)
- Simulations (1)
- Sonne (1)
- Spectroscopy (1)
- Spektroskopie (1)
- Spike sequences (1)
- Spiralgalaxien: Magnetfelder (1)
- Stalagmite (1)
- Stars: atmospheres early type (1)
- Stars: mass-loss (1)
- Stars: winds (1)
- Stellar winds (1)
- Stellardynamik (1)
- Stochastic modelling (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)
- Theorie (1)
- Thermoakustik (1)
- Thermodynamics of adsorption (1)
- Thermophon (1)
- Tilt angles (1)
- Trace elements (1)
- Tropics (1)
- Turbulenzmessung (1)
- Typ III (1)
- Van Allen Probes (1)
- Venus, surface (1)
- Wartezeitverteilung (1)
- Water distribution systems (1)
- Water/air interface (1)
- Wechselwirkung (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)
- Zufallsbewegung (1)
- accretion, accretion disks (1)
- active transport (1)
- advective-diffusive codes (1)
- allgemeine Relativitätstheorie (1)
- anomalous dynamics with memory (1)
- anti-Stokes resonant x-ray raman scattering (1)
- arktische Atmosphäre (1)
- astrobiology (1)
- astrochemistry (1)
- astroparticle physics (1)
- atmospheric boundary layer (1)
- atmosphärische Grenzschicht (1)
- atomic data (1)
- atomtronics (1)
- azobenzene containing polymer films (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)
- bond (1)
- cell wall deficient mutant (1)
- chaos (1)
- charge accumulation (1)
- charge carrier transport (1)
- charge transfer (1)
- chromatin (1)
- chromium hexacarbonyl (1)
- coherence (1)
- collective dynamics (1)
- comb-like model (1)
- conduction (1)
- conductivity (1)
- conservation laws (1)
- continuous time random walk (1)
- coronal mass ejections (CMEs) (1)
- cosmic ray dynamo (1)
- cosmic ray theory (1)
- cosmic rays (1)
- cosmology (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)
- dissertation (1)
- distance scale (1)
- diurnal rhythm (1)
- domain memory in polymer brushes (1)
- dynamics (1)
- dynamo theory (1)
- eingefrorene Energielandschaft (1)
- elastomers (1)
- electric field noise (1)
- electron number density (1)
- entanglement (1)
- enzymatic activity (1)
- enzymatische Reaktionen (1)
- epigenetics (1)
- errata, addenda (1)
- excited state selectivity (1)
- extraterrestrial intelligence (1)
- femtosecond slicing (1)
- ferroelectric polymer (1)
- field-effect-transistor (1)
- first arrival (1)
- first passage (1)
- first passage process (1)
- first passage time (1)
- fluctuating surfaces (1)
- fluctuation dissipation (1)
- fluctuation-dissipation theorem (1)
- food security (1)
- free electron lasers (1)
- free shear layers (1)
- galactic astronomy (1)
- galaktische Astronomie (1)
- galaxies (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)
- gene expression (1)
- generalised Langevin equation (1)
- globular clusters: individual: (SMASH 1) (1)
- globular clusters: individual: 47 Tucanae (1)
- gravitational waves (1)
- group field theory (1)
- großräumige Strukturen (1)
- halo (1)
- heat diffusion (1)
- high harmonic (1)
- high harmonic generation (1)
- high redshift galaxies (1)
- histone modifications (1)
- infrared: galaxies (1)
- infrared: stars (1)
- inner magnetosphere (1)
- inner radiation zone and slot region (1)
- instability control (1)
- integrability (1)
- integral field spectroscopy (1)
- ion trap (1)
- ionic conductivity (1)
- ionic liquids (1)
- ionogels (1)
- ionosphere (1)
- iron pentacarbonyl (1)
- kosmische Strahlung Dynamo (1)
- large-scale structure formation (1)
- ligand (1)
- light driven reversible change of surface topography and thickness (1)
- line: identification (1)
- line: profiles (1)
- linear response theory (1)
- linker histones (1)
- liquid crystal alignment (1)
- magnetic fields (1)
- magnetic flux tubes (1)
- magnetohydrodynamics (1)
- massive Schwarze Löcher (1)
- massive black holes (1)
- mean squared displacement (1)
- mechanical properties (1)
- metal carbonyls (1)
- meteorological extremes (1)
- micrometeorology (1)
- microstructure (1)
- mock data catalogues (1)
- molecular crowding (1)
- molecular doping (1)
- molecular dynamics (1)
- morphology (1)
- motion of adsorbed nano-particles (1)
- mu CT imaging (1)
- nanoscale friction and thermal noise (1)
- nanostructures (1)
- neural networks (1)
- nichlineare Phononik (1)
- nichtlineare Dynamo (1)
- nichtlineare Wellenmischung (1)
- noise in biochemical signalling (1)
- non-local field theory (1)
- nonliear dynamo (1)
- nonlinear acoustics (1)
- nonlinear microscopy (1)
- nucleosome (1)
- numerical experiments (1)
- numerical schemes (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)
- perturbation theory (1)
- phase grating (1)
- phase separation (1)
- photo electron spectroscopy (1)
- photoacoustic effect (1)
- photoakustischer Effekt (1)
- photodissociation (1)
- photosensitive brushes (1)
- photosynthesis (1)
- physical chemistry (1)
- planetary nebulae: general (1)
- planets and satellites: fundamental parameters (1)
- planets and satellites: individual: Jupiter (1)
- plasma physics (1)
- plasmaspheric hiss (1)
- plasmonics (1)
- predator-prey model (1)
- probability density function (1)
- proper motions (1)
- protein folding (1)
- pulsars: individual (PSR J1023+0038) (1)
- pump-probe (1)
- quantum effects (1)
- quantum eraser (1)
- quantum optics (1)
- quasars (1)
- quasars: general (1)
- quasars: individual (SDSS J142253.31-000149) (1)
- quasars: individual (SDSS J213748+001220, SDSS J215200+062516) (1)
- quasi-periodic oscillation (1)
- quenched energy landscape (1)
- radiative transfer (1)
- radio burst (1)
- random search process (1)
- random walks (1)
- recurrence (1)
- regional climate modelling (1)
- regionale Klimamodellierung (1)
- remanent polarisation (1)
- remodelers (1)
- resonant inelastic x-ray scattering (1)
- second-harmonic generation (1)
- self-steepening (1)
- semiconducting polymers (1)
- sensors and actuators (1)
- single-cell analysis (1)
- single-file motion (1)
- solar wind (1)
- spiral galaxies: magnetic fields (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 102ka (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)
- stellar dynamics (1)
- stellar physics (1)
- stochastic models (1)
- stochastic processes (1)
- sudden stratosphere warming (1)
- sun (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)
- theory (1)
- thermoacoustic effect (1)
- thermoacoustics (1)
- thermoakustischer Effekt (1)
- thermodynamic efficiency (1)
- thermophone (1)
- topologically associated domains (1)
- trade shocks (1)
- tropical cyclones (1)
- tunneling (1)
- turbulence control (1)
- turbulence measurement (1)
- type III (1)
- ultracold atoms (1)
- ultrafast X-ray diffraction (1)
- ultrafast dynamics (1)
- ultrafast photochemistry (1)
- ultrafast spectroscopy (1)
- ultraschnelle Dynamik (1)
- virtual observatory tools (1)
- visibility (1)
- white dwarfs (1)
- x-ray diffraction (1)
- zweite Harmonische (1)
Institute
- Institut für Physik und Astronomie (258) (remove)
The aim of this study was to develop a one-step synthesis of gold nanotriangles (NTs) in the presence of mixed phospholipid vesicles followed by a separation process to isolate purified NTs. Negatively charged vesicles containing AOT and phospholipids, in the absence and presence of additional reducing agents (polyampholytes, polyanions or low molecular weight compounds), were used as a template phase to form anisotropic gold nanoparticles. Upon addition of the gold chloride solution, the nucleation process is initiated and both types of particles, i.e., isotropic spherical and anisotropic gold nanotriangles, are formed simultaneously. As it was not possible to produce monodisperse nanotriangles with such a one-step procedure, the anisotropic nanoparticles needed to be separated from the spherical ones. Therefore, a new type of separation procedure using combined polyelectrolyte/micelle depletion flocculation was successfully applied. As a result of the different purification steps, a green colored aqueous dispersion was obtained containing highly purified, well-defined negatively charged flat nanocrystals with a platelet thickness of 10 nm and an edge length of about 175 nm. The NTs produce promising results in surface-enhanced Raman scattering.
Physiological response of two different Chlamydomonas reinhardtii strains to light-dark rhythms
(2016)
Cells of a cell-wall deficient line (cw15-type) of Chlamydomonas reinhardtii and of the corresponding wild type were grown during repetitive light-dark cycles. In a direct comparison, both lines showed approximately the same relative biomass increase during light phase but the cw-line produced significantly more, and smaller, daughter cells. Throughout the light period the average cellular starch content, the cellular chlorophyll content, the cellular rate of dark respiration, and the cellular rate of photosynthesis of the cw-line was lower. Despite this, several non-cell volume related parameters like the development of starch content per cell volume were clearly different over time between the strains. Additionally, the chlorophyll-based photosynthesis rates were 2-fold higher in the mutant than in the wild-type cells, and the ratio of chlorophyll a to chlorophyll b as well as the light-saturation index were also consistently higher in the mutant cells. Differences in the starch content were also confirmed by single cell analyses using a sensitive SHG-based microscopy approach. In summary, the cw15-type mutant deviates from its genetic background in the entire cell physiology. Both lines should be used in further studies in comparative systems biology with focus on the detailed relation between cell volume increase, photosynthesis, starch metabolism, and daughter cell productivity.
Even if greenhouse gas emissions were stopped today, sea level would continue to rise for centuries, with the long-term sea-level commitment of a 2 degrees C warmer world significantly exceeding 2 m. In view of the potential implications for coastal populations and ecosystems worldwide, we investigate, from an ice-dynamic perspective, the possibility of delaying sea-level rise by pumping ocean water onto the surface of the Antarctic ice sheet. We find that due to wave propagation ice is discharged much faster back into the ocean than would be expected from a pure advection with surface velocities. The delay time depends strongly on the distance from the coastline at which the additional mass is placed and less strongly on the rate of sea-level rise that is mitigated. A millennium-scale storage of at least 80% of the additional ice requires placing it at a distance of at least 700 km from the coastline. The pumping energy required to elevate the potential energy of ocean water to mitigate the currently observed 3 mmyr(-1) will exceed 7% of the current global primary energy supply. At the same time, the approach offers a comprehensive protection for entire coastlines particularly including regions that cannot be protected by dikes.
We consider a generalized diffusion equation in two dimensions for modeling diffusion on a comb-like structures. We analyze the probability distribution functions and we derive the mean squared displacement in x and y directions. Different forms of the memory kernels (Dirac delta, power-law, and distributed order) are considered. It is shown that anomalous diffusion may occur along both x and y directions. Ultraslow diffusion and some more general diffusive processes are observed as well. We give the corresponding continuous time random walk model for the considered two dimensional diffusion-like equation on a comb, and we derive the probability distribution functions which subordinate the process governed by this equation to the Wiener process.
We introduce azobenzene-functionalized polyelectrolyte multilayers as efficient, inexpensive optoacoustic transducers for hyper-sound strain waves in the GHz range. By picosecond transient reflectivity measurements we study the creation of nanoscale strain waves, their reflection from interfaces, damping by scattering from nanoparticles and propagation in soft and hard adjacent materials like polymer layers, quartz and mica. The amplitude of the generated strain epsilon similar to 5 x 10(-4) is calibrated by ultrafast X-ray diffraction.
Polymer-dispersed liquid crystals (PDLCs) of ferroelectric poly(vinylidene fluoride-trifluoroethylene) and nematic 4-cyano-4ʹ-n-hexylbiphenyl (6CB) or 4-cyano-4ʹ-n-pentylbiphenyl (5CB) were prepared to study the effect of the remanent polarisation of the polymer on the liquid crystal alignment. We measured the macroscopic alignment of the liquid crystal molecules in the thickness direction by means of Infrared Transition-Moment Orientational Analysis. Electrical poling at 100 V/µm caused an increased order parameter up to 0.15. After subsequent annealing above the nematic-to-isotropic phase-transition temperature, the order parameter was reduced to 0.02. Nevertheless, the order parameter was still higher than for non-poled film indicating a slight orientation in thickness direction. Both values are lower than those expected from model calculations. In agreement with dielectric measurements, we attribute this result to the shielding effect of mobile charge carriers within the liquid crystal inclusions.
In low-accumulation regions, the reliability of delta O-18-derived temperature signals from ice cores within the Holocene is unclear, primarily due to the small climate changes relative to the intrinsic noise of the isotopic signal. In order to learn about the representativity of single ice cores and to optimise future ice-core-based climate reconstructions, we studied the stable-water isotope composition of firn at Kohnen Station, Dronning Maud Land, Antarctica. Analysing delta O-18 in two 50m long snow trenches allowed us to create an unprecedented, two-dimensional image characterising the isotopic variations from the centimetre to the 100-metre scale. Our results show seasonal layering of the isotopic composition but also high horizontal isotopic variability caused by local stratigraphic noise. Based on the horizontal and vertical structure of the isotopic variations, we derive a statistical noise model which successfully explains the trench data. The model further allows one to determine an upper bound for the reliability of climate reconstructions conducted in our study region at seasonal to annual resolution, depending on the number and the spacing of the cores taken.
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 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.
A topic of intense current investigation pursues the question of how the highly crowded environment of biological cells affects the dynamic properties of passively diffusing particles. Motivated by recent experiments we report results of extensive simulations of the motion of a finite sized tracer particle in a heterogeneously crowded environment made up of quenched distributions of monodisperse crowders of varying sizes in finite circular two-dimensional domains. For given spatial distributions of monodisperse crowders we demonstrate how anomalous diffusion with strongly non-Gaussian features arises in this model system. We investigate both biologically relevant situations of particles released either at the surface of an inner domain or at the outer boundary, exhibiting distinctly different features of the observed anomalous diffusion for heterogeneous distributions of crowders. Specifically we reveal an asymmetric spreading of tracers even at moderate crowding. In addition to the mean squared displacement (MSD) and local diffusion exponent we investigate the magnitude and the amplitude scatter of the time averaged MSD of individual tracer trajectories, the non-Gaussianity parameter, and the van Hove correlation function. We also quantify how the average tracer diffusivity varies with the position in the domain with a heterogeneous radial distribution of crowders and examine the behaviour of the survival probability and the dynamics of the tracer survival probability. Inter alia, the systems we investigate are related to the passive transport of lipid molecules and proteins in two-dimensional crowded membranes or the motion in colloidal solutions or emulsions in effectively two-dimensional geometries, as well as inside supercrowded, surface adhered cells.