1,294 research outputs found
The 69 ms Radio Pulsar Near the Supernova Remnant RCW 103
We report the detection of the radio pulsar counterpart to the 69 ms X-ray
pulsar discovered near the supernova remnant RCW 103 (G332.4-0.4). Our
detection confirms that the pulsations arise from a rotation-powered neutron
star, which we name PSR J1617-5055. The observed barycentric period derivative
confirms that the pulsar has a characteristic age of only 8 kyr, the sixth
smallest of all known pulsars. The unusual apparent youth of the pulsar and its
proximity to a young remnant requires that an association be considered.
Although the respective ages and distances are consistent within substantial
uncertainties, the large inferred pulsar transverse velocity is difficult to
explain given the observed pulsar velocity distribution, the absence of
evidence for a pulsar wind nebula, and the symmetry of the remnant. Rather, we
argue that the objects are likely superposed on the sky; this is reasonable
given the complex area. Without an association, the question of where is the
supernova remnant left behind following the birth of PSR J1617-5055 remains
open. We also discuss a possible association between PSR J1617-5055 and the
gamma-ray source 2CG 333+01. Though an association is energetically plausible,
it is unlikely given that EGRET did not detect 2CG 333+01.Comment: 18 pages, 2 encapsulated Postscript figures, uses AAS LaTeX style
files. Accepted for publication in The Astrophysical Journal Letter
Identification of the Mass Donor Star's Spectrum in SS 433
We present spectroscopy of the microquasar SS 433 obtained near primary
eclipse and disk precessional phase Psi = 0.0, when the accretion disk is
expected to be most ``face-on''. The likelihood of observing the spectrum of
the mass donor is maximized at this combination of orbital and precessional
phases since the donor is in the foreground and above the extended disk
believed to be present in the system. The spectra were obtained over four
different runs centered on these special phases. The blue spectra show clear
evidence of absorption features consistent with a classification of A3-7 I. The
behavior of the observed lines indicates an origin in the mass donor. The
observed radial velocity variations are in anti-phase to the disk, the
absorption lines strengthen at mid-eclipse when the donor star is expected to
contribute its maximum percentage of the total flux, and the line widths are
consistent with lines created in an A supergiant photosphere. We discuss and
cast doubt on the possibility that these lines represent a shell spectrum
rather than the mass donor itself. We re-evaluate the mass ratio of the system
and derive masses of 10.9 +/- 3.1 Msun and 2.9 +/- 0.7 Msun for the mass donor
and compact object plus disk, respectively. We suggest that the compact object
is a low mass black hole.
In addition, we review the behavior of the observed emission lines from both
the disk/wind and high velocity jets.Comment: submitted to ApJ, 24 pages, 7 figure
Improvement in IAPT outcomes over time: are they driven by changes in clinical practice?
Treatment outcomes across Improving Access to Psychological Therapies (IAPT) services in England have improved year-on-year, with the national average proportion of patients in recovery at the end of treatment now exceeding the 50% target. This is despite the number of referrals and numbers of treated patients also increasing year-on-year, suggesting that services have evolved local practices and treatment delivery to meet needs whilst improving performance. This study explores whether there have been changes in clinical practice with regard to: (1) the number of sessions and length of treatments; (2) the number of cancellations and non-attendance; and (3) the recording of problem descriptor information, and the association with treatment outcomes in IAPT. Routinely collected data from seven IAPT services involved in the North and Central East London (NCEL) IAPT Service Improvement and Research Network (SIRN) were brought together to form a dataset of nearly 88,000 patients who completed a course of IAPT treatment. Results showed that there was a slight increase in the average number of sessions, and decreases in the length of time in treatment, as well as decreases in both the number of non-attended appointments and the use of inappropriate problem descriptors. These findings highlight a number of areas where potentially small changes to clinical practice may have had positive effects on patient outcomes. The value of using IAPT data to inform service improvement evaluations is discussed
Formation of a disk-structure and jets in the symbiotic prototype Z And during its 2006-2010 active phase
We present an analysis of spectrophotometric observations of the latest cycle
of activity of the symbiotic binary Z And from 2006 to 2010. We estimate the
temperature of the hot component of Z And to be \approx 150000 - 170000 K at
minimum brightness, decreasing to \approx 90000 K at the brightness maximum.
Our estimate of the electron density in the gaseous nebula is
N_{e}=10^{10}-10^{12} cm^{-3} in the region of formation of lines of neutral
helium and 10^6-10^7 cm^{-3} in the region of formation of the [OIII] and
[NeIII] nebular lines. A trend for the gas density derived from helium lines to
increase and the gas density derived from [OIII] and [NeIII] lines to
simultaneously decrease with increasing brightness of the system was observed.
Our estimates show that the ratios of the theoretical and observed fluxes in
the [OIII] and [NeIII] lines agree best when the O/Ne ratio is similar to its
value for planetary nebulae. The model spectral energy distribution showed
that, in addition to a cool component and gaseous nebula, a relatively cool
pseudophotosphere (5250-11 500 K) is present in the system. The simultaneous
presence of a relatively cool pseudophotosphere and high-ionization spectral
lines is probably related to a disk-like structure of the pseudophotosphere.
The pseudophotosphere formed very rapidly, over several weeks, during a period
of increasing brightness of Z And. We infer that in 2009, as in 2006, the
activity of the system was accompanied by a collimated bipolar ejection of
matter. In contrast to the situation in 2006, the jets were detected even
before the system reached its maximum brightness. Moreover, components with
velocities close to 1200 km/s disappeared at the maximum, while those with
velocities close to 1800 km/s appeared.Comment: 18 pages, 19 figures, Accepted for publication in Astronomy Report
Understanding the psychological therapy treatment outcomes for young adults who are not in education, employment, or training (NEET), moderators of outcomes, and what might be done to improve them
Background:
To determine: whether young adults (aged 18â24) not in education, employment or training (NEET) have different psychological treatment outcomes to other young adults; any socio-demographic or treatment-related moderators of differential outcomes; and whether service-level changes are associated with better outcomes for those who are NEET.
Methods:
A cohort was formed of 20 293 young adults treated with psychological therapies in eight Improving Access to Psychological Therapies services. Pre-treatment characteristics, outcomes, and moderators of differential outcomes were compared for those who were and were not NEET. Associations between outcomes and the following were assessed for those that were NEET: missing fewer sessions, attending more sessions, having a recorded diagnosis, and waiting fewer days between referral and starting treatment.
Results:
Those who were NEET had worse outcomes: odds ratio (OR) [95% confidence interval (CI)] for reliable recovery = 0.68 (0.63â0.74), for deterioration = 1.41 (1.25â1.60), and for attrition = 1.31 (1.19â1.43). Ethnic minority participants that were NEET had better outcomes than those that were White and NEET. Living in deprived areas was associated with worse outcomes. The intensity of treatment (high or low) did not moderate outcomes, but having more sessions was associated with improved outcomes for those that were NEET: odds (per one-session increase) of reliable recovery = 1.10 (1.08â1.12), deterioration = 0.94 (0.91â0.98), and attrition = 0.68 (0.66â0.71).
Conclusions:
Earlier treatment, supporting those that are NEET to attend sessions, and in particular, offering them more sessions before ending treatment might be effective in improving clinical outcomes. Additional support when working with White young adults that are NEET and those in more deprived areas may also be important
TAUVEX: status in 2011
We present a short history of the TAUVEX instrument, conceived to provide
multi-band wide-field imaging in the ultraviolet, emphasizing the lack of
sufficient and aggressive support on the part of the different space agencies
that dealt with this basic science mission. First conceived in 1985 and
selected by the Israel Space Agency in 1989 as its first priority payload,
TAUVEX is fast becoming one of the longest-living space project of space
astronomy. After being denied a launch on a national Israeli satellite, and
then not flying on the Spectrum X-Gamma (SRG) international observatory, it was
manifested since 2003 as part of ISRO's GSAT-4 Indian satellite to be launched
in the late 2000s. However, two months before the launch, in February 2010, it
was dismounted from its agreed-upon platform. This proved to be beneficial,
since GSAT-4 and its launcher were lost on April 15 2010 due to the failure of
the carrier rocket's 3rd stage. TAUVEX is now stored in ISRO's clean room in
Bangalore with no firm indications when or on what platform it might be
launched.Comment: Invited contribution presented at the "UV Universe 2010". Accepted
for publication in Astrophysics & Space Scienc
The detailed optical light curve of GRB 030329
(Abridged) We present densely sampled BVRI light curves of the optical
transient associated with the gamma-ray burst GRB 030329, the result of a
coordinated observing campaign conducted at five observatories. Augmented with
published observations of this GRB, the compiled optical dataset contains 2687
photometric measurements, obtained between 78 minutes and 79 days after the
burst. We show that the underlying supernova 2003dh evolved faster than, and
was probably somewhat fainter than the type Ic SN 1998bw, associated with GRB
980425. We find that our data can be described by a broken power-law decay
perturbed by a complex variable component. The early- and late-time decay
slopes are determined to be ~1.1 and ~2, respectively. Assuming this single
power-law model, we constrain the break to lie between ~3 and ~8 days after the
burst. This simple, singly-broken power-law model, derived only from the
analysis of our optical observations, may also account for available multi-band
data, provided that the break happened ~8 days after the burst. The more
complex double-jet model of Berger et al. provides a comparable fit to the
optical, X-ray, mm and radio observations of this event. We detect a
significant change in optical colors during the first day. Our color analysis
is consistent with a cooling break frequency sweeping through the optical band
during the first day. The light curves of GRB 030329 reveal a rich array of
variations, superposed over the mean power-law decay. We find that the early
variations are asymmetric, with a steep rise followed by a relatively slower
(by a factor of about two) decline. The variations maintain a similar time
scale during the first four days, and then get significantly longer.Comment: 14 pages, 12 figures, accepted for publication in ApJ with minor
changes. See the GRB030329 Data Treasury at
http://wise-obs.tau.ac.il/GRB030329
Effect of saxagliptin on renal outcomes in the SAVOR-TIMI 53 trial.
OBJECTIVE: Dipeptidyl peptidase 4 inhibitors may have a protective effect in diabetic nephropathy. RESEARCH DESIGN AND METHODS: We studied renal outcomes of 16,492 patients with type 2 diabetes, randomized to saxagliptin versus placebo and followed for a median of 2.1 years in the Saxagliptin Assessment of Vascular Outcomes Recorded in Patients with Diabetes Mellitus Thrombolysis in Myocardial Infarction 53 trial. RESULTS: At baseline: 9,696 (58.8%) subjects had normoalbuminuria (albumin/creatinine ratio [ACR] 300 mg/g). Treatment with saxagliptin was associated with improvement in and/or less deterioration in ACR categories from baseline to end of trial (EOT) (P = 0.021, P 50 mL/min/BSA, -105 mg/g (P = 0.011) for 50 â„ eGFR â„ 30 mL/min/BSA, and -245.2 mg/g (P = 0.086) for eGFR 6.0 mg/dL, were similar as well. CONCLUSIONS: Treatment with saxagliptin improved ACR, even in the normoalbuminuric range, without affecting eGFR. The beneficial effect of saxagliptin on albuminuria could not be explained by its effect on glycemic control
Gravitational Microlensing Evidence for a Planet Orbiting a Binary Star System
The study of extra-solar planetary systems has emerged as a new discipline of
observational astronomy in the past few years with the discovery of a number of
extra-solar planets. The properties of most of these extra-solar planets were
not anticipated by theoretical work on the formation of planetary systems. Here
we report observations and light curve modeling of gravitational microlensing
event MACHO-97-BLG-41, which indicates that the lens system consists of a
planet orbiting a binary star system. According to this model, the mass ratio
of the binary star system is 3.8:1 and the stars are most likely to be a late K
dwarf and an M dwarf with a separation of about 1.8 AU. A planet of about 3
Jupiter masses orbits this system at a distance of about 7 AU. If our
interpretation of this light curve is correct, it represents the first
discovery of a planet orbiting a binary star system and the first detection of
a Jovian planet via the gravitational microlensing technique. It suggests that
giant planets may be common in short period binary star systems.Comment: 11 pages, with 1 color and 2 b/w Figures included (published version
Radiation-Driven Warping. II. Non-Isothermal Disks
Recent work by Pringle and by Maloney, Begelman & Pringle has shown that
geometrically thin, optically thick, accretion disks are unstable to warping
driven by radiation torque from the central source. In this paper we generalize
the study of radiation-driven warping to include general power-law surface
density distributions, . We consider the range
(isothermal disks) to , which corresponds to a
radiation-pressure-supported disk; this spans the range of surface density
distributions likely to be found in real astrophysical disks. There is a
critical minimum size for unstable disks. The critical radius and the
steady-state precession rate depend only weakly on . The case
divides the solutions into two qualitatively different regimes.
Nonlinear effects must be important if the warp extends to the disk inner edge
for , but for nonlinearity will be important only if
the warp amplitude is large at the origin. The effects of shadowing of the
central source by the warp will thus be very different in the two regimes of
In real accretion disks the outer boundary condition is likely to be
different from the zero-crossing condition that we have assumed. In accretion
disks around massive black holes in active galactic nuclei, the disk will
probably become optically thin before the outer disk boundary is reached, while
in X-ray binaries, there will be an outer disk region (outside the
circularization radius) in which the inflow velocity is zero but angular
momentum is still transported. We show that in both these cases the solutions
are similar to the zero-crossing eigenfunctions.Comment: 43 pages, 16 figures, to appear in The Astrophysical Journa
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