809 research outputs found
Abundant Methanol Masers but no New Evidence for Star Formation in GCM0.253+0.016
We present new observations of the quiescent giant molecular cloud
GCM0.253+0.016 in the Galactic center, using the upgraded Karl G. Jansky Very
Large Array. Observations were made at wavelengths near 1 cm, at K (24 to 26
GHz) and Ka (27 and 36 GHz) bands, with velocity resolutions of 1-3 km/s and
spatial resolutions of ~0.1 pc, at the assumed 8.4 kpc distance of this cloud.
The continuum observations of this cloud are the most sensitive yet made, and
reveal previously undetected emission which we attribute primarily to free-free
emission from external ionization of the cloud. In addition to the sensitive
continuum map, we produce maps of 12 molecular lines: 8 transitions of NH3 --
(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7) and (9,9), as well as the HC3N (3-2)
and (4-3) lines, and CH3OH 4(-1) - 3(0) the latter of which is known to be a
collisionally-excited maser. We identify 148 CH3OH 4(-1) - 3(0) (36.2 GHz)
sources, of which 68 have brightness temperatures in excess of the highest
temperature measured for this cloud (400 K) and can be confirmed to be masers.
The majority of these masers are concentrated in the southernmost part of the
cloud. We find that neither these masers nor the continuum emission in this
cloud provide strong evidence for ongoing star formation in excess of that
previously inferred by the presence of an H2O maser.Comment: 33 pages, 4 tables, 9 figures; ApJ Accepte
A 610-MHz Galactic Plane Pulsar Search with the Giant Meterwave Radio Telescope
We report on the discovery of three new pulsars in the first blind survey of
the north Galactic plane (45 < l < 135 ; |b| < 1) with the Giant Meterwave
Radio telescope (GMRT) at an intermediate frequency of 610 MHz. The timing
parameters, obtained in follow up observations with the Lovell Telescope at
Jodrell Bank Observatory and the GMRT, are presented.Comment: 2 pages, 1 figure, to be published in conference proceedings of "40
years of pulsars ..", replaced figure
The Threat of Plant Toxins and Bioterrorism: A Review
The intentional use of highly pathogenic microorganisms, such as bacteria, viruses or their toxins, to spread mass-scale diseases that destabilize populations (with motivations of religious or ideological belief, monetary implications, or political decisions) is defined as bioterrorism. Although the success of a bioterrorism attack is not very realistic due to technical constraints, it is not unlikely and the threat of such an attack is higher than ever before. It is now a fact that the capability to create panic has allured terrorists for the use of biological agents (BAs) to cause terror attacks. In the era of biotechnology and nanotechnology, accessibility in terms of price and availability has spread fast, with new sophisticated BAs often being produced and used. Moreover, there are some BAs that are becoming increasingly important, such as toxins produced by bacteria (e.g., Botulinum toxin, BTX), or Enterotoxyn type B, also known as Staphylococcal Enterotoxin B (SEB)) and extractions from plants. The most increasing records are with regards to the extraction / production of ricin, abrin, modeccin, viscumin and volkensin, which are the most lethal plant toxins known to humans, even in low amounts. Moreover, ricin was also developed as an aerosol biological warfare agent (BWA) by the US and its allies during World War II, but was never used. Nowadays, there are increasing records that show how easy it can be to extract plant toxins and transform them into biological weapon agents (BWAs), regardless of the scale of the group of individuals
Discovery of three new pulsars in a 610 MHz pulsar survey with the GMRT
We report on the discovery of three new pulsars in the first blind survey of
the north Galactic plane (45 degrees < l < 135 degrees; |b| < 1 degrees with
the Giant Meterwave Radio telescope (GMRT) at an intermediate frequency of 610
MHz. The survey covered 106 square degrees with a sensitivity of roughly 1 mJy
to long-period pulsars (pulsars with period longer than 1 s). The three new
pulsars have periods of 318, 933, and 1056 ms. Their timing parameters and flux
densities, obtained in follow up observations with the Lovell Telescope at
Jodrell Bank and the GMRT, are presented. We also report on pulse nulling
behaviour in one of the newly discovered pulsars, PSR J2208+5500.Comment: Accepted for publication in MNRAS, 7 pages, 5 figures, 2 table
The UA9 experimental layout
The UA9 experimental equipment was installed in the CERN-SPS in March '09
with the aim of investigating crystal assisted collimation in coasting mode.
Its basic layout comprises silicon bent crystals acting as primary
collimators mounted inside two vacuum vessels. A movable 60 cm long block of
tungsten located downstream at about 90 degrees phase advance intercepts the
deflected beam.
Scintillators, Gas Electron Multiplier chambers and other beam loss monitors
measure nuclear loss rates induced by the interaction of the beam halo in the
crystal. Roman pots are installed in the path of the deflected particles and
are equipped with a Medipix detector to reconstruct the transverse distribution
of the impinging beam. Finally UA9 takes advantage of an LHC-collimator
prototype installed close to the Roman pot to help in setting the beam
conditions and to analyze the efficiency to deflect the beam. This paper
describes in details the hardware installed to study the crystal collimation
during 2010.Comment: 15pages, 11 figure, submitted to JINS
Search for Charged Current Coherent Pion Production on Carbon in a Few-GeV Neutrino Beam
The SciBooNE Collaboration has performed a search for charged current
coherent pion production from muon neutrinos scattering on carbon, \nu_\mu
^{12}C \to \mu^- ^{12}C \pi^+, with two distinct data samples. No evidence for
coherent pion production is observed. We set 90% confidence level upper limits
on the cross section ratio of charged current coherent pion production to the
total charged current cross section at 0.67\times 10^{-2} at mean neutrino
energy 1.1 GeV and 1.36\times 10^{-2} at mean neutrino energy 2.2 GeV.Comment: 18 pages, 16 figures, Minor revisions to match version accepted for
publication in Physical Review
Measurement of inclusive charged current interactions on carbon in a few-GeV neutrino beam
The SciBooNE Collaboration reports a measurement of inclusive charged current
interactions of muon neutrinos on carbon with an average energy of 0.8 GeV
using the Fermilab Booster Neutrino Beam. We compare our measurement with two
neutrino interaction simulations: NEUT and NUANCE. The charged current
interaction rates (product of flux and cross section) are extracted by fitting
the muon kinematics, with a precision of 6-15% for the energy dependent and 3%
for the energy integrated analyses. We also extract CC inclusive interaction
cross sections from the observed rates, with a precision of 10-30% for the
energy dependent and 8% for the energy integrated analyses. This is the first
measurement of the CC inclusive cross section on carbon around 1 GeV. These
results can be used to convert previous SciBooNE cross section ratio
measurements to absolute cross section values.Comment: 21 pages, 16 figures. Accepted by Phys. Rev. D. Minor revisions to
match the accepted versio
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