28,423 research outputs found
Parton Production Via Vacuum Polarization
We discuss the production mechanism of partons via vacuum polarization during
the very early, gluon dominated phase of an ultrarelativistic heavy-ion
collision in the framework of the background field method of quantum
chromodynamics.Comment: 3 pages, Latex, 3 figures (eps), to be published in JPhysG, SQM2001
proceeding
{BiQ} Analyzer {HiMod}: An Interactive Software Tool for High-throughput Locus-specific Analysis of 5-Methylcytosine and its Oxidized Derivatives
Recent data suggest important biological roles for oxidative modifications of methylated cytosines, specifically hydroxymethylation, formylation and carboxylation. Several assays are now available for profiling these DNA modifications genome-wide as well as in targeted, locus-specific settings. Here we present BiQ Analyzer HiMod, a user-friendly software tool for sequence alignment, quality control and initial analysis of locus-specific DNA modification data. The software supports four different assay types, and it leads the user from raw sequence reads to DNA modification statistics and publication-quality plots. BiQ Analyzer HiMod combines well-established graphical user interface of its predecessor tool, BiQ Analyzer HT, with new and extended analysis modes. BiQ Analyzer HiMod also includes updates of the analysis workspace, an intuitive interface, a custom vector graphics engine and support of additional input and output data formats. The tool is freely available as a stand-alone installation package from http://biq-analyzer-himod.bioinf.mpi-inf.mpg.de/
Volumetric measurement of tank volume
A method is disclosed for determining the volume of compressible gas in a system including incompressible substances in a zero-gravity environment consisting of measuring the change in pressure (delta P) for a known volume change rate (delta V/delta t) in the polytrophic region between isothermal and adiabatic conditions. The measurements are utilized in an idealized formula for determining the change in isothermal pressure (delta P sub iso) for the gas. From the isothermal pressure change (delta iso) the gas volume is obtained. The method is also applicable to determination of gas volume by utilizing work (W) in the compression process. In a passive system, the relationship of specific densities can be obtained
Anisotropic pair-superfluidity of trapped two-component Bose gases
We theoretically investigate the pair-superfluid phase of two-component
ultracold gases with negative inter-species interactions in an optical lattice.
We establish the phase diagram for filling at zero and finite
temperature, by applying Bosonic Dynamical Mean-Field Theory, and confirm the
stability of pair-superfluidity for asymmetric hopping of the two species.
While the pair superfluid is found to be robust in the presence of a harmonic
trap, we observe that it is destroyed already by a small population imbalance
of the two species.Comment: 7 pages, 11 figure
A perturbation density functional theory for the competition between inter and intramolecular association
Using the framework of Wertheim's thermodynamic perturbation theory we
develop the first density functional theory which accounts for intramolecular
association in chain molecules. To test the theory new Monte Carlo simulations
are performed at a fluid solid interface for a 4 segment chain which can both
intra and intermolecularly associate. The theory and simulation results are
found to be in excellent agreement. It is shown that the inclusion of
intramolecular association can have profound effects on interfacial properties
such as interfacial tension and the partition coefficient
Standard Model couplings and collider signatures of a light scalar
The electroweak symmetry breaking (EWSB) sector of the Standard Model can be
far richer and more interesting than the usual single scalar doublet model. We
explore scenarios where the EWSB sector is nearly scale invariant and
consequently gives rise to a light CP even scalar particle. The one-doublet SM
is in that category, as are many other models with either weakly or strongly
coupled sectors that trigger EWSB. We study the couplings of the light scalar
to the SM particles that can arise from the explicit breaking of scale
invariance focusing on the possible differences with the minimal SM. The
couplings of the light scalar to light fermions, as well as to the massless
gauge bosons, can be significantly enhanced. We find possible new discovery
channels due to the decays of the conformal scalar into e^+e^- and mu^+mu^-
pairs as well as new production channels via light quark annihilation.Comment: 10 pages, 7 figure
Structure and Dynamics of amorphous Silica Surfaces
We use molecular dynamics computer simulations to study the equilibrium
properties of the surface of amorphous silica. Two types of geometries are
investigated: i) clusters with different diameters (13.5\AA, 19\AA, and
26.5\AA) and ii) a thin film with thickness 29\AA. We find that the shape of
the clusters is independent of temperature and that it becomes more spherical
with increasing size. The surface energy is in qualitative agreement with the
experimental value for the surface tension. The density distribution function
shows a small peak just below the surface, the origin of which is traced back
to a local chemical ordering at the surface. Close to the surface the partial
radial distribution functions as well as the distributions of the bond-bond
angles show features which are not observed in the interior of the systems. By
calculating the distribution of the length of the Si-O rings we can show that
these additional features are related to the presence of two-membered rings at
the surface. The surface density of these structures is around 0.6/nm^2 in good
agreement with experimental estimates. From the behavior of the mean-squared
displacement at low temperatures we conclude that at the surface the cage of
the particles is larger than the one in the bulk. Close to the surface the
diffusion constant is somewhat larger than the one in the bulk and with
decreasing temperature the relative difference grows. The total vibrational
density of states at the surface is similar to the one in the bulk. However, if
only the one for the silicon atoms is considered, significant differences are
found.Comment: 30 pages of Latex, 16 figure
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