8,980 research outputs found
Survey of Ices toward Massive Young Stellar Objects: I. OCS, CO, OCN, and CHOH
An important tracer of the origin and evolution of cometary ices is the
comparison with ices found in dense clouds and towards Young Stellar Objects
(YSOs). We present a survey of ices in the 2-5 micron spectra of 23 massive
YSOs, taken with the NASA InfraRed Telescope Facility SpeX spectrometer. The
4.90 micron absorption band of OCS ice is detected in 20 sight-lines, more than
five times the previously known detections. The absorption profile shows little
variation and is consistent with OCS being embedded in CH3OH-rich ices, or
proton-irradiated HS or SO-containing ices. The OCS column densities
correlate well with those of CHOH and OCN, but not with HO and
apolar CO ice. This association of OCS with CHOH and OCN firmly
establishes their formation location deep inside dense clouds or protostellar
envelopes. The median composition of this ice phase towards massive YSOs, as a
percentage of HO, is CO:CHOH:OCN:OCS=24:20:1.53:0.15. CS, due to
its low abundance, is likely not the main precursor to OCS. Sulfurization of CO
is likely needed, although the source of this sulfur is not well constrained.
Compared to massive YSOs, low mass YSOs and dense clouds have similar CO and
CHOH ice abundances, but less OCN and more apolar CO, while OCS awaits
detection. Comets tend to be under-abundant in carbon-bearing species, but this
does not appear to be the case for OCS, perhaps signalling OCS production in
protoplanetary disks.Comment: 35 pages, 18 figures. Published ApJ 941, 32. Updated arXiv title and
publication informatio
Cumulus cloud venting of mixed layer ozone
Observations are presented which substantiate the hypothesis that significant vertical exchange of ozone and aerosols occurs between the mixed layer and the free troposphere during cumulus cloud convective activity. The experiments utilized the airborne Ultra-Violet Differential Absorption Lidar (UV-DIAL) system. This system provides simultaneous range resolved ozone concentration and aerosol backscatter profiles with high spatial resolution. Evening transects were obtained in the downwind area where the air mass had been advected. Space-height analyses for the evening flight show the cloud debris as patterns of ozone typically in excess of the ambient free tropospheric background. This ozone excess was approximately the value of the concentration difference between the mixed layer and free troposphere determined from independent vertical soundings made by another aircraft in the afternoon
Muon-spin-rotation measurements of the penetration depth in Li_2Pd_3B
Measurements of the magnetic field penetration depth in the ternary
boride superconductor LiPdB ( K) have been carried out by
means of muon-spin rotation (SR). The absolute values of , the
Ginzburg-Landau parameter , and the first and the second
critical fields at T=0 obtained from SR were found to be
nm, , mT, and
T, respectively. The zero-temperature value of the
superconducting gap 1.31(3) meV was found, corresponding to the
ratio . At low temperatures saturates and
becomes constant below , in agreement with what is expected for
s-wave BCS superconductors. Our results suggest that LiPdB is a s-wave
BCS superconductor with the only one isotropic energy gap.Comment: 6 pages, 7 figure
A decidable policy language for history-based transaction monitoring
Online trading invariably involves dealings between strangers, so it is
important for one party to be able to judge objectively the trustworthiness of
the other. In such a setting, the decision to trust a user may sensibly be
based on that user's past behaviour. We introduce a specification language
based on linear temporal logic for expressing a policy for categorising the
behaviour patterns of a user depending on its transaction history. We also
present an algorithm for checking whether the transaction history obeys the
stated policy. To be useful in a real setting, such a language should allow one
to express realistic policies which may involve parameter quantification and
quantitative or statistical patterns. We introduce several extensions of linear
temporal logic to cater for such needs: a restricted form of universal and
existential quantification; arbitrary computable functions and relations in the
term language; and a "counting" quantifier for counting how many times a
formula holds in the past. We then show that model checking a transaction
history against a policy, which we call the history-based transaction
monitoring problem, is PSPACE-complete in the size of the policy formula and
the length of the history. The problem becomes decidable in polynomial time
when the policies are fixed. We also consider the problem of transaction
monitoring in the case where not all the parameters of actions are observable.
We formulate two such "partial observability" monitoring problems, and show
their decidability under certain restrictions
Fe I Oscillator Strengths for the Gaia-ESO Survey
The Gaia-ESO Public Spectroscopic Survey (GES) is conducting a large-scale
study of multi-element chemical abundances of some 100 000 stars in the Milky
Way with the ultimate aim of quantifying the formation history and evolution of
young, mature and ancient Galactic populations. However, in preparing for the
analysis of GES spectra, it has been noted that atomic oscillator strengths of
important Fe I lines required to correctly model stellar line intensities are
missing from the atomic database. Here, we present new experimental oscillator
strengths derived from branching fractions and level lifetimes, for 142
transitions of Fe I between 3526 {\AA} and 10864 {\AA}, of which at least 38
are urgently needed by GES. We also assess the impact of these new data on
solar spectral synthesis and demonstrate that for 36 lines that appear
unblended in the Sun, Fe abundance measurements yield a small line-by-line
scatter (0.08 dex) with a mean abundance of 7.44 dex in good agreement with
recent publications.Comment: Accepted for publication in Mon. Not. R. Astron. So
Contemplating Mindfulness at Work: An Integrative Review
Mindfulness research activity is surging within organizational science. Emerging evidence across multiple fields suggests that mindfulness is fundamentally connected to many aspects of workplace functioning, but this knowledge base has not been systematically integrated to date. This review coalesces the burgeoning body of mindfulness scholarship into a framework to guide mainstream management research investigating a broad range of constructs. The framework identifies how mindfulness influences attention, with downstream effects on functional domains of cognition, emotion, behavior, and physiology. Ultimately, these domains impact key workplace outcomes, including performance, relationships, and well-being. Consideration of the evidence on mindfulness at work stimulates important questions and challenges key assumptions within management science, generating an agenda for future research
Assessment of Metal Mining-Contaminated River Sediments in England and Wales
This report reviews how sediments and floodplain soils have been contaminated by abandoned metal mines and recommends what the Environment Agency should do about this issue
Territorial Tactics: The Socio-spatial Significance of Private Policing Strategies in Cape Town
This paper analyses the policing strategies of private security companies operating in urban space. An existing literature has considered the variety of ways that territory becomes of fundamental importance in the work of public police forces. However, this paper examines territory in the context of private security companies. Drawing on empirical research in Cape Town, it examines how demarcated territories become key subjects in private policing. Private security companies are responsible for a relatively small section of the city, while in contrast the public police ultimately have to see city space as a whole. Hence, private policing strategy becomes one of displacement, especially of so-called undesirables yielding a patchworked public space associated with private enclaves of consumption. The conclusions signal the historical resonances and comparative implications of these political-legal-security dynamics. © 2013 Urban Studies Journal Limited
Microsomal incubation test of potentially hemolytic drugs for glucose‐6‐phosphate dehydrogenase deficiency
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109761/1/cptclpt198354.pd
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