825 research outputs found
Non-Thermal Continuum toward SGRB2(N-LMH)
An analysis of continuum antenna temperatures observed in the Green Bank
Telescope (GBT) spectrometer bandpasses is presented for observations toward
SgrB2(N-LMH). Since 2004, we have identified four new prebiotic molecules
toward this source by means of rotational transitions between low energy
levels; concurrently, we have observed significant continuum in the GBT
spectrometer bandpasses centered at 85 different frequencies in the range of 1
to 48 GHz. The continuum heavily influences the molecular spectral features
since we have observed far more absorption lines than emission lines for each
of these new molecular species. Hence, it is important to understand the
nature, distribution, and intensity of the underlying continuum in the GBT
bandpasses for the purposes of radiative transfer, i.e. the means by which
reliable molecular abundances are estimated. We find that the GBT spectrometer
bandpass continuum is consistent with optically-thin, non thermal (synchrotron)
emission with a flux density spectral index of -0.7 and a Gaussian source size
of ~143" at 1 GHz that decreases with increasing frequency as nu^(-0.52). Some
support for this model is provided by high frequency Very Large Array (VLA)
observations of SgrB2.Comment: Accepted for Publication in the Astrophysical Journal Letter
Comment on ``Large-space shell-model calculations for light nuclei''
In a recent publication Zheng, Vary, and Barrett reproduced the negative
quadrupole moment of Li-6 and the low-lying positive-parity states of He-5 by
using a no-core shell model. In this Comment we question the meaning of these
results by pointing out that the model used is inadequate for the reproduction
of these properties.Comment: Latex with Revtex, 1 postscript figure in separate fil
Agrodat: A Knowledge Centre and Decision Support System for Precision Farming Based on IoT and Big Data Technologies
Since 2014 the Agrodat project and its collaborating partners have been working on introducing new, cost-effective sensor technologies and advanced ICT solutions for the Hungarian agriculture sector. Currently, 50 farmers and other targeted user communities have access to data analytics services with automatic warnings in case of hazardous conditions
Receptors of peptides as therapeutic targets in epilepsy research
Neuropeptides are signaling molecules participating in the modulation of synaptic transmission. Neuropeptides are stored in dense core synaptic vesicles, the release of which requires profound excitation. Only in the extracellular space, neuropeptides act on G-protein coupled receptors to exert a relatively slow action both pre- and postsynaptically. Consequently, neuropeptide modulators are ideal candidates to influence epileptic tissue overexcited during seizures. Indeed, a number of neuropeptides have receptors implicated in epilepsy and many of them are considered to participate in endogenous neuroprotective actions. Neuropeptide receptors, present in the hippocampus, the most frequent focus of seizures in temporal lobe epilepsy, received the largest attention as potential anti-epileptic targets. Receptors of hippocampal neuropeptides, somatostatin, neuropeptide Y, galanin, dynorphin, enkephalin, substance P, cholecystokinin, vasoactive intestinal polypeptide, and receptors of some neuropeptides, which are also hormones such as ghrelin, angiotensins, corticotropin- releasing hormone, adrenocorticotropin, thyrotropin-releasing hormone, oxytocin and vasopressin involved in epilepsy are discussed in the review article. Activation and inhibition of receptors by oral application of peptides as drugs is typically not efficient because of low bioavailability: rapid degradation and insufficient penetration of peptides through the blood-brain barrier. Recent progress in the development of non-peptide agonists and antagonists of neuropeptide receptors as well as gene therapeutic approaches leading to the local production of agonists and antagonists within the central nervous system will also be discussed
Microscopic multicluster description of neutron-halo nuclei with a stochastic variational method
To test a multicluster approach for halo nuclei, we give a unified
description for the ground states of He and He in a model comprising an
cluster and single-neutron clusters. The intercluster wave function is
taken a superposition of terms belonging to different arrangements, each
defined by a set of Jacobi coordinates. Each term is then a superposition of
products of gaussian functions of the individual Jacobi coordinates with
different widths, projected to angular momenta or 1. To avoid excessively
large dimensions and ``overcompleteness", stochastic methods were tested for
selecting the gaussians spanning the basis. For He, we were able to
calculate ground-state energies that are virtully exact within the subspace
defined by the arrangements and values, and we found that preselected
random sets of bases (with or without simulated annealing) yield excellent
numerical convergence to this ``exact" value with thoroughly truncated bases.
For He good energy convergence was achieved in a state space comprising
three arrangements with all , and there are indications showing that the
contributions of other subspaces are likely to be small. The He and He
energies are reproduced by the same effective force very well, and the matter
radii obtained are similar to those of other sophisticated calculations.Comment: Latex , 8 figures available on request, ATOMKI-4-1993-
Resonance phenomena in ultracold dipole-dipole scattering
Elastic scattering resonances occurring in ultracold collisions of either
bosonic or fermionic polar molecules are investigated. The Born-Oppenheimer
adiabatic representation of the two-bodydynamics provides both a qualitative
classification scheme and a quantitative WKB quantization condition that
predicts several sequences of resonant states. It is found that the
near-threshold energy dependence of ultracold collision cross sections varies
significantly with the particle exchange symmetry, with bosonic systems showing
much smoother energy variations than their fermionic counterparts. Resonant
variations of the angular distributions in ultracold collisions are also
described.Comment: 19 pages, 6 figures, revtex4, submitted to J. Phys.
Phase-shift calculation using continuum-discretized states
We present a method for calculating scattering phase shifts which utilizes
continuum-discretized states obtained in a bound-state type calculation. The
wrong asymptotic behavior of the discretized state is remedied by means of the
Green's function formalism. Test examples confirm the accuracy of the method.
The scattering is described using realistic nucleon-nucleon
potentials. The and phase shifts obtained in a single-channel
calculation are too small in comparison with experiment. The phase
shifts are in reasonable agreement with experiment, and gain contributions both
from the tensor and central components of the nucleon-nucleon potential.Comment: 16 pages, 5 figure
- …