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CO and CI maps of the starburst galaxy M82
The first map of an external galaxy in the 3Pâ - 3P0 fine-structure line of atomic carbon (CI) is presented towards the nucleus of the starbuster M82, and compared with the distinction of the CO J = 4 - 3 molecular emission. The CI traces features that are seen in lower transition CO maps, and shows that CI and the CO are well mixed and have similar spatial distributions. There are small differences between the CO J = 4 - 3 line and lower transition CO data towards the NE part of the molecular ring, where the emission is less prominent. The abundance ratio [CI]/[CO] across M82 is very high, with an average value ~ 0.5 across most of the nucleus, a factor at least 5 times that which is typical of dense molecular cloud cores seen in our own Galaxy. This means that on average, CI is overabundant towards M82. This result can be explained using models which provide enhancements to the CI abundance above normal Interstellar Medium values, a result of a greater cosmic ray flux in M82, or where there is substantial mixing of the gas
Heat bounds and the blowtorch theorem
We study driven systems with possible population inversion and we give
optimal bounds on the relative occupations in terms of released heat. A precise
meaning to Landauer's blowtorch theorem (1975) is obtained stating that
nonequilibrium occupations are essentially modified by kinetic effects. Towards
very low temperatures we apply a Freidlin-Wentzel type analysis for continuous
time Markov jump processes. It leads to a definition of dominant states in
terms of both heat and escape rates.Comment: 11 pages; v2: minor changes, 1 reference adde
PersonâCentered Emotional Support and Gender Attributions in ComputerâMediated Communication
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98127/1/hcre12006.pd
PON1 status does not influence cholinesterase activity in Egyptian agricultural workers exposed to chlorpyrifos.
Animal studies have shown that paraoxonase 1 (PON1) genotype can influence susceptibility to the organophosphorus pesticide chlorpyrifos (CPF). However, Monte Carlo analysis suggests that PON1 genotype may not affect CPF-related toxicity at low exposure conditions in humans. The current study sought to determine the influence of PON1 genotype on the activity of blood cholinesterase as well as the effect of CPF exposure on serum PON1 in workers occupationally exposed to CPF. Saliva, blood and urine were collected from agricultural workers (n=120) from Egypt's Menoufia Governorate to determine PON1 genotype, blood cholinesterase activity, serum PON1 activity towards chlorpyrifos-oxon (CPOase) and paraoxon (POase), and urinary levels of the CPF metabolite 3,5,6-trichloro-2-pyridinol (TCPy). The PON1 55 (Pâ€0.05) but not the PON1 192 genotype had a significant effect on CPOase activity. However, both the PON1 55 (Pâ€0.05) and PON1 192 (Pâ€0.001) genotypes had a significant effect on POase activity. Workers had significantly inhibited AChE and BuChE after CPF application; however, neither CPOase activity nor POase activity was associated with ChE depression when adjusted for CPF exposure (as determined by urinary TCPy levels) and stratified by PON1 genotype. CPOase and POase activity were also generally unaffected by CPF exposure although there were alterations in activity within specific genotype groups. Together, these results suggest that workers retained the capacity to detoxify chlorpyrifos-oxon under the exposure conditions experienced by this study population regardless of PON1 genotype and activity and that effects of CPF exposure on PON1 activity are minimal
KECK HIRES Spectroscopy of APM 08279+5255
With an optical R-band magnitude of 15.2, the recently discovered z=3.911 BAL
quasar APM 08279+5255 is an exceptionally bright high redshift source. Its
brightness has allowed us to acquire a high signal-to-noise ratio (~100), high
resolution (~6 km/s) spectrum using the HIRES echelle spectrograph on the 10-m
Keck I telescope. Given the quality of the data, these observations provide an
unprecedented view of associated and intervening absorption systems. Here we
announce the availability of this spectrum to the general astronomical
community and present a brief analysis of some of its main features.Comment: 21 pages including 5 figures. Accepted for publication by PAS
Probing Sub-parsec Structure in the Lyman Alpha Forest with Gravitational Microlensing
We present the results of microlens ray-tracing simulations showing the
effect of absorbing material between a source quasar and a lensing galaxy in a
gravitational lens system. We find that, in addition to brightness fluctuations
due to microlensing, the strength of the absorption line relative to the
continuum varies with time, with the properties of the variations depending on
the structure of the absorbing material. We conclude that such variations will
be measurable via UV spectroscopy of image A of the gravitationally lensed
quasar Q2237+0305 if the Lyman Alpha clouds between the quasar and the lensing
galaxy possess structure on scales smaller than pc. The time scale
for the variations is on the order of order years to decades, although very
short term variability can occur. While the Lyman alpha lines may not be
accessible at all wavelengths, this approach is applicable to any absorption
system, including metal lines.Comment: 8 pages, 11 figures, to appear in MNRAS (note resolution of some
figures reduced due to size limitations
Acceleration of Solar Wind Ions by Nearby Interplanetary Shocks: Comparison of Monte Carlo Simulations with Ulysses Observations
The most stringent test of theoretical models of the first-order Fermi
mechanism at collisionless astrophysical shocks is a comparison of the
theoretical predictions with observational data on particle populations. Such
comparisons have yielded good agreement between observations at the
quasi-parallel portion of the Earth's bow shock and three theoretical
approaches, including Monte Carlo kinetic simulations. This paper extends such
model testing to the realm of oblique interplanetary shocks: here observations
of proton and alpha particle distributions made by the SWICS ion mass
spectrometer on Ulysses at nearby interplanetary shocks are compared with test
particle Monte Carlo simulation predictions of accelerated populations. The
plasma parameters used in the simulation are obtained from measurements of
solar wind particles and the magnetic field upstream of individual shocks. Good
agreement between downstream spectral measurements and the simulation
predictions are obtained for two shocks by allowing the the ratio of the
mean-free scattering length to the ionic gyroradius, to vary in an optimization
of the fit to the data. Generally small values of this ratio are obtained,
corresponding to the case of strong scattering. The acceleration process
appears to be roughly independent of the mass or charge of the species.Comment: 26 pages, 6 figures, AASTeX format, to appear in the Astrophysical
Journal, February 20, 199
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