5,254 research outputs found
Redshifts in the Southern Abell Redshift Survey Clusters. I. The Data
The Southern Abell Redshift Survey contains 39 clusters of galaxies with
redshifts in the range 0.0 < z < 0.31 and a median redshift depth of z =
0.0845. SARS covers the region 0 21h (while
avoiding the LMC and SMC) with b > 40. Cluster locations were chosen from the
Abell and Abell-Corwin-Olowin catalogs while galaxy positions were selected
from the Automatic Plate Measuring Facility galaxy catalog with
extinction-corrected magnitudes in the range 15 <= b_j < 19. SARS utilized the
Las Campanas 2.5 m duPont telescope, observing either 65 or 128 objects
concurrently over a 1.5 sq deg field. New redshifts for 3440 galaxies are
reported in the fields of these 39 clusters of galaxies.Comment: 20 pages, 5 figures, accepted for publication in the Astronomical
Journal, Table 2 can be downloaded in its entirety from
http://trotsky.arc.nasa.gov/~mway/SARS1/sars1-table2.cs
The Abundance of SiC2 in Carbon Star Envelopes: Evidence that SiC2 is a gas-phase precursor of SiC dust
Silicon carbide dust is ubiquitous in circumstellar envelopes around C-rich
AGB stars. However, the main gas-phase precursors leading to the formation of
SiC dust have not yet been identified. The most obvious candidates among the
molecules containing an Si--C bond detected in C-rich AGB stars are SiC2, SiC,
and Si2C. We aim to study how widespread and abundant SiC2, SiC, and Si2C are
in envelopes around C-rich AGB stars and whether or not these species play an
active role as gas-phase precursors of silicon carbide dust in the ejecta of
carbon stars. We carried out sensitive observations with the IRAM 30m telescope
of a sample of 25 C-rich AGB stars to search for emission lines of SiC2, SiC,
and Si2C in the 2 mm band. We performed non-LTE excitation and radiative
transfer calculations based on the LVG method to model the observed lines of
SiC2 and to derive SiC2 fractional abundances in the observed envelopes. We
detect SiC2 in most of the sources, SiC in about half of them, and do not
detect Si2C in any source, at the exception of IRC +10216. Most of these
detections are reported for the first time in this work. We find a positive
correlation between the SiC and SiC2 line emission, which suggests that both
species are chemically linked, the SiC radical probably being the
photodissociation product of SiC2 in the external layer of the envelope. We
find a clear trend in which the denser the envelope, the less abundant SiC2 is.
The observed trend is interpreted as an evidence of efficient incorporation of
SiC2 onto dust grains, a process which is favored at high densities owing to
the higher rate at which collisions between particles take place. The observed
behavior of a decline in the SiC2 abundance with increasing density strongly
suggests that SiC2 is an important gas-phase precursor of SiC dust in envelopes
around carbon stars.Comment: Published in A&A. 16 pages and 10 figure
Clues to NaCN formation
ALMA is providing us essential information on where certain molecules form.
Observing where these molecules emission arises from, the physical conditions
of the gas, and how this relates with the presence of other species allows us
to understand the formation of many species, and to significantly improve our
knowledge of the chemistry that occurs in the space. We studied the molecular
distribution of NaCN around IRC +10216, a molecule detected previously, but
whose origin is not clear. High angular resolution maps allow us to model the
abundance distribution of this molecule and check suggested formation paths. We
modeled the emission of NaCN assuming local thermal equilibrium (LTE)
conditions. These profiles were fitted to azimuthal averaged intensity profiles
to obtain an abundance distribution of NaCN. We found that the presence of NaCN
seems compatible with the presence of CN, probably as a result of the
photodissociation of HCN, in the inner layers of the ejecta of IRC +10216.
However, similar as for CH 3 CN, current photochemical models fail to reproduce
this CN reservoir. We also found that the abundance peak of NaCN appears at a
radius of 3 x 10 15 cm, approximately where the abundance of NaCl, suggested to
be the parent species, starts to decay. However, the abundance ratio shows that
the NaCl abundance is lower than that obtained for NaCN. We expect that the LTE
assumption might result in NaCN abundances higher than the real ones. Updated
photochemical models, collisional rates, and reaction rates are essential to
determine the possible paths of the NaCN formation.Comment: 7 pages, 10 figures. Accepted for publication in A&A letter
Introduction to the Special Issue related to the Power Aware Computing Workshop 2019 — PACO 2019
The RASSCALS: An X-ray and Optical Study of 260 Galaxy Groups
We describe the ROSAT All-Sky Survey-Center for Astrophysics Loose Systems
(RASSCALS), the largest X-ray and optical survey of low mass galaxy groups to
date. We draw 260 groups from the combined Center for Astrophysics and Southern
Sky Redshift Surveys, covering one quarter of the sky to a limiting Zwicky
magnitude of 15.5. We detect 61 groups (23%) as extended X-ray sources.
The statistical completeness of the sample allows us to make the first
measurement of the X-ray selection function of groups, along with a clean
determination of their fundamental scaling laws. We find robust evidence of
similarity breaking in the relationship between the X-ray luminosity and
velocity dispersion. Groups with sigma < 340 km/s are overluminous by several
orders of magnitude compared to the familiar LX ~ sigma^4 law for higher
velocity dispersion systems. An understanding of this break depends on the
detailed structure of groups with small velocity dispersions sigma < 150 km/s.Comment: 16 pages, including 6 figures. To appear in The Astrophysical Journa
An Inversion Disrupting FAM134B Is Associated with Sensory Neuropathy in the Border Collie Dog Breed
Sensory neuropathy in the Border Collie is a severe neurological disorder caused by the degeneration of sensory and, to a lesser extent, motor nerve cells with clinical signs starting between 2 and 7 months of age. Using a genome-wide association study approach with three cases and 170 breed matched controls, a suggestive locus for sensory neuropathy was identified that was followed up using a genome sequencing approach. An inversion disrupting the candidate gene FAM134B was identified. Genotyping of additional cases and controls and RNAseq analysis provided strong evidence that the inversion is causal. Evidence of cryptic splicing resulting in novel exon transcription for FAM134B was identified by RNAseq experiments. This investigation demonstrates the identification of a novel sensory neuropathy associated mutation, by mapping using a minimal set of cases and subsequent genome sequencing. Through mutation screening, it should be possible to reduce the frequency of or completely eliminate this debilitating condition from the Border Collie breed population
Evaluation of an enhanced service for medication review with follow up in Swiss community pharmacies: Pre-post study protocol.
In Switzerland, 20,000 people are hospitalized each year as result of drug related problems (DRPs). The sources of DRPs can be related to patients' behavior (i.e., wrong administration) or to health processes (i.e., drug-drug interaction). No community pharmacy (CP) service focus on DRPs related to patients' behavior is currently recognized or remunerated in Switzerland. A medication review with follow up (MRF) has been developed to evaluate prescription and non-prescription medication.
To evaluate the impact of MRF service for the identification and management DRPs associated to patients' behavior and to describe pharmaceutical interventions carried out through MRF.
A pre-post intervention study with a cluster design and one intervention group will be carried out in CPs in the canton of Vaud (Switzerland) for 15 months. Volunteer pharmacists will be trained on the identification and management of DRPs related to patients' behavior. After training, they will include randomly selected adults taking four or more chronic drugs prescribed for at least three months prior to recruitment. Then, they will conduct three pharmacist-patient face-to-face consultations at 6-month intervals. Tasks will be differentiated by pharmacy technician or pharmacist to triage expired medication or to manage DRPs in a structured manner, respectively. The primary outcome is the identification of DRPs associated to patients' behavior. Secondary outcomes are to assess patients' medication knowledge, number of expired medications, interventions carried out by pharmacists and pharmacists' satisfaction. The study will begin in April 2023 in 19 to 35 pharmacies that will recruit at least 162 patients. A sub analysis will be carried out for patients with 65 years old or over.
The MRF intervention features a training designed for an enhanced evaluation of patient's behavior towards their medication. The study will allow the assessment and management of DRPs in Swiss CPs with the support of the local health authorities and pharmacist association.
Clinicaltrials.gov NCT05348538
The Optimal Gravitational Lens Telescope
Given an observed gravitational lens mirage produced by a foreground
deflector (cf. galaxy, quasar, cluster,...), it is possible via numerical lens
inversion to retrieve the real source image, taking full advantage of the
magnifying power of the cosmic lens. This has been achieved in the past for
several remarkable gravitational lens systems. Instead, we propose here to
invert an observed multiply imaged source directly at the telescope using an
ad-hoc optical instrument which is described in the present paper. Compared to
the previous method, this should allow one to detect fainter source features as
well as to use such an optimal gravitational lens telescope to explore even
fainter objects located behind and near the lens. Laboratory and numerical
experiments illustrate this new approach
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