13,968 research outputs found
Momentum Broadening of a Fast Parton in a Perturbative Quark-Gluon Plasma
The average transverse momentum transfer per unit path length to a fast
parton scattering elastically in a perturbative quark-gluon plasma is related
to the radiative energy loss of the parton. We first calculate the momentum
transfer coefficient in terms of a classical Langevin problem and then
define it quantum-mechanically through scattering matrix element. After
treating the well known case of a quark-gluon plasma in equilibrium we consider
an off-equilibrium unstable plasma. As a specific example, we treat the
two-stream plasma with unstable modes of longitudinal chromoelectric field. In
the presence of the instabilities, is shown to exponentially grow in
time.Comment: Updated version containing an analysis of insufficiencies in previous
calculations of momentum broadening in unstable plasma
„Man muss sich darauf einlassen, auf die dänische Mentalität“ – Funktionale Angemessenheit in der deutsch-dänischen interkulturellen Kommunikation
This paper is based on results of the research project National stereotypes and marketing strategies in the intercultural Danish-German communication (SMiK). In the SMiK-project, we define stereotypes as linguistically and culturally determined patterns of thinking and behaving. Such patterns affect intercultural interactions and they should therefore be taken into consideration in the teaching of foreign languages and in intercultural communication. In the SMiK-project we have developed guidelines for the adequate intercultural interaction in the German-Danish business communication. Those guidelines are based on empirical studies on German-Danish national stereotypes. In this paper, we will discuss the theoretical and methodological approach to the compilation of these guidelines and their background in studies on intercultural communication and in the Sprachkritik-paradigm (a linguistically founded critical-reflecting appraisal of language use) will be described. We hereby focus on the concepts of ‘Weltansichten’ as conceptualizations of the world, cultural awareness and functional adequacy in the intercultural communication. Finally, we give examples for the implementation of the results from an analyses of interview data in guidelines for Danish-German business communication
Rotational spectra of isotopic species of methyl cyanide, CHCN, in their ground vibrational states up to terahertz frequencies
Methyl cyanide is an important trace molecule in star-forming regions. It is
one of the more common molecules used to derive kinetic temperatures in such
sources. As preparatory work for Herschel, SOFIA, and in particular ALMA we
want to improve the rest frequencies of the main as well as minor isotopologs
of methyl cyanide. The laboratory rotational spectrum of methyl cyanide in
natural isotopic composition has been recorded up to 1.63 THz. Transitions with
good signal-to-noise ratio could be identified for CHCN, CHCN,
CHCN, CHCN, CHDCN, and CHCN in their
ground vibrational states up to about 1.2 THz. The main isotopic species could
be identified even in the highest frequency spectral recordings around 1.6 THz.
The highest quantum numbers included in the fit are 64 for
CHCN and 89 for the main isotopic species. Greatly improved
spectroscopic parameters have been obtained by fitting the present data
together with previously reported transition frequencies. The present data will
be helpful to identify isotopologs of methyl cyanide in the higher frequency
bands of instruments such as the recently launched Herschel satellite, the
upcoming airplane mission SOFIA or the radio telescope array ALMA.Comment: 13 pages, 2 figures, article appeared; CDMS links update
Avalanches in mean-field models and the Barkhausen noise in spin-glasses
We obtain a general formula for the distribution of sizes of "static
avalanches", or shocks, in generic mean-field glasses with
replica-symmetry-breaking saddle points. For the Sherrington-Kirkpatrick (SK)
spin-glass it yields the density rho(S) of the sizes of magnetization jumps S
along the equilibrium magnetization curve at zero temperature. Continuous
replica-symmetry breaking allows for a power-law behavior rho(S) ~ 1/(S)^tau
with exponent tau=1 for SK, related to the criticality (marginal stability) of
the spin-glass phase. All scales of the ultrametric phase space are implicated
in jump events. Similar results are obtained for the sizes S of static jumps of
pinned elastic systems, or of shocks in Burgers turbulence in large dimension.
In all cases with a one-step solution, rho(S) ~ S exp(-A S^2). A simple
interpretation relating droplets to shocks, and a scaling theory for the
equilibrium analog of Barkhausen noise in finite-dimensional spin glasses are
discussed.Comment: 6 pages, 1 figur
Phase-locking of two self-seeded tapered amplifier lasers
We report on the phase-locking of two diode lasers based on self-seeded
tapered amplifiers. In these lasers, a reduction of linewidth is achieved using
narrow-band high-transmission interference filters for frequency selection. The
lasers combine a compact design with a Lorentzian linewidth below 200 kHz at an
output power of 300 mW. We characterize the phase noise of the phase-locked
laser system and study its potential for coherent beam-splitting in atom
interferometers.Comment: 7 pages, 4 figure
65 Cybele in the thermal infrared: Multiple observations and thermophysical analysis
We investigated the physical and thermal properties of 65 Cybele}, one of the
largest main-belt asteroids. Based on published and recently obtained thermal
infrared observations, including ISO measurements, we derived through
thermophysical modelling (TPM) a size of 302x290x232 km (+/- 4 %) and an
geometric visible albedo of 0.050+/-0.005. Our model of a regolith covered
surface with low thermal inertia and "default" roughness describes the
wavelengths and phase angle dependent thermal aspects very well. Before/after
opposition effect and beaming behaviour can be explained in that way. We found
a constant emissivity of 0.9 at wavelengths up to about 100 micron and lower
values towards the submillimetre range, indicating a grain size distribution
dominated by 200 micron particle sizes. The spectroscopic analysis revealed an
emissivity increase between 8.0 and 9.5 micron. We compared this emissivity
behaviour with the Christiansen features of carbonaceous chondrite meteorites,
but a conclusive identification was not possible. A comparison between the
Standard Thermal Model (STM) and the applied TPM clearly demonstrates the
limitations and problems of the STM for the analysis of multi-epoch and
-wavelengths observations. While the TPM produced a unique diameter/albedo
solution, the calculated STM values varied by +/-30 % and showed clear trends
with wavelength and phase angle. Cybele can be considered as a nice textbook
case for the thermophysical analysis of combined optical and thermal infrared
observations.Comment: 11 pages, 8 figures, accepted for publication by A&
Adeno-associated virus capsid protein expression in Escherichia coli and chemically defined capsid assembly
Le DT, Radukic M, Müller K. Adeno-associated virus capsid protein expression in Escherichia coli and chemically defined capsid assembly. Scientific Reports. 2019;9(1): 18631.Research and clinical applications of recombinant adeno-associated virus (rAAV) significantly increased in recent years alongside regulatory approvals of rAAV gene therapy products. To date, all rAAV vectors as well as AAV empty capsids are produced in eukaryotic cells. We explored a new route to generate AAV capsids with the aim to analyze capsid assembly in a chemically defined setting and pave the way for new production methods and applications based on AAV virus-like particles (VLPs). We generated these empty capsids by bacterial expression and subsequent concomitant protein refolding and VLP formation. AAV serotype 2 structural protein VP3 was expressed in Escherichia coli. VLPs formed as demonstrated by dynamic light scattering, atomic force microscopy, and ELISA. Furthermore, VLPs internalized into human HeLa cells. To extend the application range of the VLPs, we tested peptide insertions, at the genetic level, in a surface loop (amino acid position 587) or at the C-terminus of VP3 and these variants also formed VLPs. VLPs developed without assembly-activating protein (AAP), but adding purified recombinant AAP to the refolding process increased capsid yield. Our findings offer a new route to understand AAV assembly biology and open a toolbox for AAV production strategies that might enable capsid display for vaccination and matching of capsids with cargoes at large scale and low cost
Cusps and shocks in the renormalized potential of glassy random manifolds: How Functional Renormalization Group and Replica Symmetry Breaking fit together
We compute the Functional Renormalization Group (FRG) disorder- correlator
function R(v) for d-dimensional elastic manifolds pinned by a random potential
in the limit of infinite embedding space dimension N. It measures the
equilibrium response of the manifold in a quadratic potential well as the
center of the well is varied from 0 to v. We find two distinct scaling regimes:
(i) a "single shock" regime, v^2 ~ 1/L^d where L^d is the system volume and
(ii) a "thermodynamic" regime, v^2 ~ N. In regime (i) all the equivalent
replica symmetry breaking (RSB) saddle points within the Gaussian variational
approximation contribute, while in regime (ii) the effect of RSB enters only
through a single anomaly. When the RSB is continuous (e.g., for short-range
disorder, in dimension 2 <= d <= 4), we prove that regime (ii) yields the
large-N FRG function obtained previously. In that case, the disorder correlator
exhibits a cusp in both regimes, though with different amplitudes and of
different physical origin. When the RSB solution is 1-step and non- marginal
(e.g., d < 2 for SR disorder), the correlator R(v) in regime (ii) is
considerably reduced, and exhibits no cusp. Solutions of the FRG flow
corresponding to non-equilibrium states are discussed as well. In all cases the
regime (i) exhibits a cusp non-analyticity at T=0, whose form and thermal
rounding at finite T is obtained exactly and interpreted in terms of shocks.
The results are compared with previous work, and consequences for manifolds at
finite N, as well as extensions to spin glasses and related models are
discussed.Comment: v2: Note added in proo
The oral sensory organs in Bathochordaeus stygius (Tunicata Appendicularia) are unique in structure and homologous to the coronal organ
The article processing charge was funded by the Open Access Publication Fund of Humboldt-Universität zu Berlin.Background: Appendicularia consists of approximately 70 purely marine species that belong to Tunicata the probable sister taxon to Craniota. Therefore, Appendicularia plays a pivotal role for our understanding of chordate evolution. In addition, appendicularians are an important part of the epipelagic marine plankton. Nevertheless, little is known about appendicularian species, especially from deeper water. Results: Using µCT, scanning electron microscopy, and digital 3D-reconstruction techniques we describe three pairs of complex oral sensory organs in the mesopelagic appendicularian Bathochordaeus stygius. The oral sensory organs are situated at the anterior and lateral margin of the mouth and inside the mouth cavity. A single organ consists of 22–90 secondary receptor cells that project apical cilia through a narrow hole in the epidermis. The receptor cells are innervated by branches of the second brain nerve. Conclusions: Based on position, morphology, and innervation we suggest that the oral sensory organs are homologues of the coronal organs in other tunicates. We discuss the hypothesized homology of coronal organs and the lateral line system of primary aquatic vertebrates. The complex oral sensory organs of B. stygius are unique in tunicates and could be adaptations to the more muffled environment of the mesopelagic.Peer Reviewe
- …