24,570 research outputs found
Pressure-control purge panel for automatic butt welding
Modification of a purge panel for use in an automatic butt weld reduces the drop in pressure between the regulators and the weld head and tube purge fitting. The invention affects air regulators for plants, regulating circuits for pneumatic valves, and automatic welding machines
Correlated D-meson decays competing against thermal QGP dilepton radiation
The QGP that might be created in ultrarelativistic heavy-ion collisions is
expected to radiate thermal dilepton radiation. However, this thermal dilepton
radiation interferes with dileptons originating from hadron decays. In the
invariant mass region between the and peak (GeVGeV) the most substantial background of hadron
decays originates from correlated D-meson decays. We evaluate
this background using a Langevin simulation for charm quarks. As background
medium we utilize the well-tested UrQMD-hybrid model. The required drag and
diffusion coefficients are taken from a resonance approach. The decoupling of
the charm quarks from the hot medium is performed at a temperature of
MeV and as hadronization mechanism a coalescence approach is chosen.
This model for charm quark interactions with the medium has already been
successfully applied to the study of the medium modification and the elliptic
flow at FAIR, RHIC and LHC energies. In this proceeding we present our results
for the dilepton radiation from correlated D decays at RHIC
energy in comparison to PHENIX measurements in the invariant mass range between
1 and 3 GeV using different interaction scenarios. These results can be
utilized to estimate the thermal QGP radiation.Comment: 4 pages, 1 figur
A High-Resolution Survey of HI Absorption toward the Central 200 pc of the Galactic Center
We present an HI absorption survey of the central 250 pc of the Galaxy. Very
Large Array (VLA) observations were made at 21 cm in the DnC and CnB
configurations and have a resolution of ~15"(0.6 pc at the Galactic Center (GC)
distance) and a velocity resolution of ~2.5 km/s. This study provides HI data
with high spatial resolution, comparable with the many high resolution
observations which have been made of GC sources over the past ten years. Here
we present an overview of the HI absorption toward ~40 well-known continuum
sources and a detailed comparison of the ionized, atomic and molecular
components of the interstellar medium for the Sgr B, Radio Arc and Sgr C
regions. In these well-known regions, the atomic gas appears to be closely
correlated in both velocity and distribution to the ionized and molecular gas,
indicating that it resides in photo-dissociation regions related to the HII
regions in the GC. Toward the majority of the radio continuum sources, HI
absorption by the 3-kpc arm is detected, constraining these sources to lie
beyond a 5 kpc distance in the Galaxy.Comment: 59 pages, including 41 figures; accepted for publication in
Astrophysical Journal Supplement Series in December 201
A partial taxonomy of judgment aggregation rules, and their properties
The literature on judgment aggregation is moving from studying impossibility
results regarding aggregation rules towards studying specific judgment
aggregation rules. Here we give a structured list of most rules that have been
proposed and studied recently in the literature, together with various
properties of such rules. We first focus on the majority-preservation property,
which generalizes Condorcet-consistency, and identify which of the rules
satisfy it. We study the inclusion relationships that hold between the rules.
Finally, we consider two forms of unanimity, monotonicity, homogeneity, and
reinforcement, and we identify which of the rules satisfy these properties
Three Concurrent Phases of Massive-Star Evolution in a Pulsar-Wind Nebula
The nebular material associated the the SNR G54.1+0.3 (hereafter G54) contains the the first reported instance of triggered star formation in the immediate vicinity of a Pulsar and its Wind Nebula (PWN). With 2MASS and Spitzer colors and followup near-IR spectroscopy, we have discovered the presence of a hot, massive and most likely evolved Be-type star among the cluster of stars hosted by the pulsar. This star has probably triggered cloud collapse and formation of at least 11 YSOs, which ring the nebula. In this unique cluster are now identified three concurrent stages of stellar evolution, from massive star birth, post-Main-Sequence transition, and stellar death
Waiting time distribution for electron transport in a molecular junction with electron-vibration interaction
On the elementary level, electronic current consists of individual electron
tunnelling events that are separated by random time intervals. The waiting time
distribution is a probability to observe the electron transfer in the detector
electrode at time given that an electron was detected in the same
electrode at earlier time . We study waiting time distribution for quantum
transport in a vibrating molecular junction. By treating the electron-vibration
interaction exactly and molecule-electrode coupling perturbatively, we obtain
master equation and compute the distribution of waiting times for electron
transport. The details of waiting time distributions are used to elucidate
microscopic mechanism of electron transport and the role of electron-vibration
interactions. We find that as nonequilibrium develops in molecular junction,
the skewness and dispersion of the waiting time distribution experience
stepwise drops with the increase of the electric current. These steps are
associated with the excitations of vibrational states by tunnelling electrons.
In the strong electron-vibration coupling regime, the dispersion decrease
dominates over all other changes in the waiting time distribution as the
molecular junction departs far away from the equilibrium
- …