3,162 research outputs found
Infrared Space Observatory Polarimetric Imaging of the Egg Nebula (RAFGL 2688)
We present polarimetric imaging of the protoplanetary nebula RAFGL 2688
obtained at 4.5 microns with the Infrared Space Observatory (ISO). We have
deconvolved the images to remove the signature of the point spread function of
the ISO telescope, to the extent possible. The deconvolved 4.5 micron image and
polarimetric map reveal a bright point source with faint, surrounding
reflection nebulosity. The reflection nebula is brightest to the
north-northeast, in agreement with previous ground- and space-based infrared
imaging. Comparison with previous near-infrared polarimetric imaging suggests
that the polarization of starlight induced by the dust grains in RAFGL 2688 is
more or less independent of wavelength between 2 microns and 4.5 microns. This,
in turn, indicates that scattering dominates over thermal emission at
wavelengths as long as ~5 microns, and that the dust grains have characteristic
radii < 1 micron.Comment: 27 pages, 9 figures; to appear in the Astronomical Journal, May 2002
issu
Quiescent H2 Emission From Pre-Main Sequence Stars in Chamaeleon I
We report the discovery of quiescent emission from molecular hydrogen gas
located in the circumstellar disks of six pre-main sequence stars, including
two weak-line T Tauri stars (TTS), and one Herbig AeBe star, in the Chamaeleon
I star forming region. For two of these stars, we also place upper limits on
the 2->1 S(1)/1->0 S(1) line ratios of 0.4 and 0.5. Of the 11 pre-main sequence
sources now known to be sources of quiescent near-infrared hydrogen emission,
four possess transitional disks, which suggests that detectable levels of H
emission and the presence of inner disk holes are correlated. These H
detections demonstrate that these inner holes are not completely devoid of gas,
in agreement with the presence of observable accretion signatures for all four
of these stars and the recent detections of [Ne II] emission from three of
them. The overlap in [Ne II] and H detections hints at a possible
correlation between these two features and suggests a shared excitation
mechanism of high energy photons. Our models, combined with the kinematic
information from the H lines, locate the bulk of the emitting gas at a few
tens of AU from the stars. We also find a correlation between H detections
and those targets which possess the largest H equivalent widths,
suggesting a link between accretion activity and quiescent H emission. We
conclude that quiescent H emission from relatively hot gas within the disks
of TTS is most likely related to on-going accretion activity, the production of
UV photons and/or X-rays, and the evolutionary status of the dust grain
populations in the inner disks.Comment: 12 pages, emulateapj, Accepted by Ap
Safety profile of statins alone or combined with ezetimibe : a pooled analysis of 27 studies including over 22,000 patients treated for 6-24 weeks
Aims:â The aim of this analysis was to assess the overall safety and tolerability profiles of various statinsâ+âezetimibe vs. statin monotherapy and to explore tolerability in sub-populations grouped by age, race, and sex. Methods:â Study-level data were combined from 27 double-blind, placebo-controlled or active-comparator trials that randomized adult hypercholesterolemic patients to statin or statinâ+âezetimibe for 6-24âweeks. In the full cohort, % patients with AEs within treatment groups (statin: Nâ=â10,517; statinâ+âezetimibe: Nâ=â11,714) was assessed by logistic regression with terms for first-/second-line therapy (first lineâ=âdrug-naĂŻve or rendered drug-naĂŻve by washout at study entry; second lineâ=âongoing statin at study entry or statin run-in), trial within first-/second-line therapy, and treatment. The same model was fitted for age (<â65, â„â65âyears), sex, race (white, black, other) and first-/second-line subgroups with additional terms for subgroup and subgroup-by-treatment interaction. Results:â In the full cohort, the only significant difference between treatments was consecutive AST or ALT elevations â„â3âĂâupper limit of normal (ULN) (statin: 0.35%, statinâ+âezetimibe: 0.56%; pâ=â0.017). Significantly more subjects reported â„â1 AE; drug-related, hepatitis-related and gastrointestinal-related AEs; and CK elevations â„â10âĂâULN (all pââ€â0.008) in first-line vs. second-line therapy studies with both treatments. AEs were generally similar between treatments in subgroups, and similar rates of AEs were reported within age and race subgroups; however, women reported generally higher AE rates. Conclusions:â In conclusion, in second-line studies, ongoing statin treatment at study entry likely screened out participants for previous statin-related AEs and tolerability issues. These results describe the safety profiles of widely used lipid-lowering therapies and encourage their appropriate and judicious use in certain subpopulations
A One Health Framework for the Evaluation of Rabies Control Programmes: A Case Study from Colombo City, Sri Lanka
<div><p>Background</p><p>One Health addresses complex challenges to promote the health of all species and the environment by integrating relevant sciences at systems level. Its application to zoonotic diseases is recommended, but few coherent frameworks exist that combine approaches from multiple disciplines. Rabies requires an interdisciplinary approach for effective and efficient management.</p><p>Methodology/Principal Findings</p><p>A framework is proposed to assess the value of rabies interventions holistically. The economic assessment compares additional monetary and non-monetary costs and benefits of an intervention taking into account epidemiological, animal welfare, societal impact and cost data. It is complemented by an ethical assessment. The framework is applied to Colombo City, Sri Lanka, where modified dog rabies intervention measures were implemented in 2007. The two options included for analysis were the control measures in place until 2006 (âbaseline scenarioâ) and the new comprehensive intervention measures (âinterventionâ) for a four-year duration. Differences in control cost; monetary human health costs after exposure; Disability-Adjusted Life Years (DALYs) lost due to human rabies deaths and the psychological burden following a bite; negative impact on animal welfare; epidemiological indicators; social acceptance of dogs; and ethical considerations were estimated using a mixed method approach including primary and secondary data. Over the four years analysed, the intervention cost US $1.03 million more than the baseline scenario in 2011 prices (adjusted for inflation) and caused a reduction in dog rabies cases; 738 DALYs averted; an increase in acceptability among non-dog owners; a perception of positive changes in society including a decrease in the number of roaming dogs; and a net reduction in the impact on animal welfare from intermediate-high to low-intermediate.</p><p>Conclusions</p><p>The findings illustrate the multiple outcomes relevant to stakeholders and allow greater understanding of the value of the implemented rabies control measures, thereby providing a solid foundation for informed decision-making and sustainable control.</p></div
On the non-abelian Brumer-Stark conjecture and the equivariant Iwasawa main conjecture
We show that for an odd prime p, the p-primary parts of refinements of the
(imprimitive) non-abelian Brumer and Brumer-Stark conjectures are implied by
the equivariant Iwasawa main conjecture (EIMC) for totally real fields.
Crucially, this result does not depend on the vanishing of the relevant Iwasawa
mu-invariant. In combination with the authors' previous work on the EIMC, this
leads to unconditional proofs of the non-abelian Brumer and Brumer-Stark
conjectures in many new cases.Comment: 33 pages; to appear in Mathematische Zeitschrift; v3 many minor
updates including new title; v2 some cohomological arguments simplified; v1
is a revised version of the second half of arXiv:1408.4934v
The Robinson Gravitational Wave Background Telescope (BICEP): a bolometric large angular scale CMB polarimeter
The Robinson Telescope (BICEP) is a ground-based millimeter-wave bolometric
array designed to study the polarization of the cosmic microwave background
radiation (CMB) and galactic foreground emission. Such measurements probe the
energy scale of the inflationary epoch, tighten constraints on cosmological
parameters, and verify our current understanding of CMB physics. Robinson
consists of a 250-mm aperture refractive telescope that provides an
instantaneous field-of-view of 17 degrees with angular resolution of 55 and 37
arcminutes at 100 GHz and 150 GHz, respectively. Forty-nine pair of
polarization-sensitive bolometers are cooled to 250 mK using a 4He/3He/3He
sorption fridge system, and coupled to incoming radiation via corrugated feed
horns. The all-refractive optics is cooled to 4 K to minimize polarization
systematics and instrument loading. The fully steerable 3-axis mount is capable
of continuous boresight rotation or azimuth scanning at speeds up to 5 deg/s.
Robinson has begun its first season of observation at the South Pole. Given the
measured performance of the instrument along with the excellent observing
environment, Robinson will measure the E-mode polarization with high
sensitivity, and probe for the B-modes to unprecedented depths. In this paper
we discuss aspects of the instrument design and their scientific motivations,
scanning and operational strategies, and the results of initial testing and
observations.Comment: 18 pages, 11 figures. To appear in Millimeter and Submillimeter
Detectors and Instrumentation for Astronomy III, Proceedings of SPIE, 6275,
200
The employment distribution and the creation of financial dependence
A fall in national income has varied consequences for the working population: some carry on working as normal, others become unemployed. Those excluded from work lose their main income source and must usually rely on public welfare, entering a financial dependence created endogenously as the economy adjusts. The current paper examines this induced financial dependence and its implications within a Post Keynesian model. A skewed employment distribution forces higher transfer payments than would occur if employment was distributed more evenly. The additional expenditures help to sustain profitability, so it is in the collective interest of employers and profit recipients to concentrate unemployment in a subset of the working population
Mapping the Shores of the Brown Dwarf Desert III: Young Moving Groups
We present the results of an aperture masking interferometry survey for
substellar companions around 67 members of the young (~8-200Myr) nearby
(~5-86pc) AB Doradus, Beta Pictoris, Hercules-Lyra, TW Hya, and
Tucana-Horologium stellar associations. Observations were made at near infrared
wavelengths between 1.2-3.8 microns using the adaptive optics facilities of the
Keck II, VLT UT4, and Palomar Hale Telescopes. Typical contrast ratios of
~100-200 were achieved at angular separations between ~40-320mas, with our
survey being 100% complete for companions with masses below 0.25\msolar across
this range. We report the discovery of a \msolar companion to
HIP14807, as well as the detections and orbits of previously known stellar
companions to HD16760, HD113449, and HD160934. We show that the companion to
HD16760 is in a face-on orbit, resulting in an upward revision of its mass from
\mjupiter to \msolar. No substellar
companions were detected around any of our sample members, despite our ability
to detect companions with masses below 80\mjupiter for 50 of our targets: of
these, our sensitivity extended down to 40\mjupiter around 30 targets, with a
subset of 22 subject to the still more stringent limit of 20\mjupiter. A
statistical analysis of our non-detection of substellar companions allows us to
place constraints on their frequency around ~0.2-1.5\msolar stars. In
particular, considering companion mass distributions that have been proposed in
the literature, we obtain an upper limit estimate of ~9-11% for the frequency
of 20-80\mjupiter companions between 3-30AU at 95% confidence, assuming that
their semimajor axes are distributed according to in this range.Comment: Accepted by Ap
The Comparative Statics of Effective Demand
Keynes introduces the term 'effective demand' in chapter 3 of the General Theory as designating the point of intersection of two functions: the 'aggregate demand function' (D) and the 'aggregate supply function' (Z). For the first time in the literature, I here specify exact functional forms for the D and Z functions and run numerical simulations which allow to study the comparative statics of the model in the face of various 'shocks'. The demonstration of how the D/Z model actually works will hopefully prove useful for future students of the economics of Keynes
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