239 research outputs found
Isolated X-ray -- infrared sources in the region of interaction of the supernova remnant IC 443 with a molecular cloud
The nature of the extended hard X-ray source XMMU J061804.3+222732 and its
surroundings is investigated using XMM-Newton, Chandra, and Spitzer
observations. This source is located in an interaction region of the IC 443
supernova remnant with a neighboring molecular cloud. The X-ray emission
consists of a number of bright clumps embedded in an extended structured
non-thermal X-ray nebula larger than 30" in size. Some clumps show evidence for
line emission at ~1.9 keV and ~3.7 keV at the 99% confidence level. Large-scale
diffuse radio emission of IC 443 passes over the source region, with an
enhancement near the source. An IR source of about 14" x 7" size is prominent
in the 24 um, 70 um, and 2.2 um bands, adjacent to a putative Si K-shell X-ray
line emission region. The observed IR/X-ray morphology and spectra are
consistent with those expected for J/C-type shocks of different velocities
driven by fragmented supernova ejecta colliding with the dense medium of a
molecular cloud. The IR emission of the source detected by Spitzer can be
attributed to both continuum emission from an HII region created by the ejecta
fragment and line emission excited by shocks. This source region in IC 443 may
be an example of a rather numerous population of hard X-ray/IR sources created
by supernova explosions in the dense environment of star-forming regions.
Alternative Galactic and extragalactic interpretations of the observed source
are also discussed.Comment: The Astrophysical Journal, v. 677 (April 2008), in pres
On the nature of the hard X-ray source IGR J2018+4043
We found a very likely counterpart to the recently discovered hard X-ray
source IGR J2018+4043 in the multi-wavelength observations of the source field.
The source, originally discovered in the 20-40 keV band, is now confidently
detected also in the 40-80 keV band, with a flux of (1.4 +/- 0.4) x 10(-11) erg
cm(-2) s(-1). A 5 ks Swift observation of the IGR J2018+4043 field revealed a
hard point-like source with the observed 0.5-10 keV flux of 3.4(+0.7)(-0.8) x
10(-12) erg cm(-2) s(-1) (90% confidence level) at alpha = 20h18m38.55s, delta
= +40d41m00.4s (with a 4.2" uncertainty). The combined Swift-INTEGRAL spectrum
can be described by an absorbed power-law model with photon index gamma = 1.3
+/- 0.2 and N_H = 6.1(+3.2)(-2.2) x 10(22) cm(-2). In archival optical and
infrared data we found a slightly extended and highly absorbed object at the
Swift source position. There is also an extended VLA 1.4 GHz source peaked at a
beam-width distance from the optical and X-ray positions. The observed
morphology and multiwavelength spectra of IGR J2018+4043 are consistent with
those expected for an obscured accreting object, i.e. an AGN or a Galactic
X-ray binary. The identification suggests possible connection of IGR J2018+4043
to the bright gamma-ray source GEV J2020+4023 (3EG J2020+4017) detected by COS
B and CGRO EGRET in the gamma-Cygni SNR field.Comment: 5 pages, 3 figures, uses emulateapj styl
Spectroscopy and Time Variability of Absorption Lines in the Direction of the Vela Supernova Remnant
We present high resolution (R~75,000), high signal-to-noise (S/N~100) Ca II
3933.663 and Na I 5889.951, 5895.924 spectra of 68
stars in the direction of the Vela supernova remnant. The spectra comprise the
most complete high resolution, high S/N, optical survey of early type stars in
this region of the sky. A subset of the sight lines has been observed at
multiple epochs, 1993/1994 and 1996. Of the thirteen stars observed twice,
seven have spectra revealing changes in the equivalent width and/or velocity
structure of lines, most of which arise from remnant gas. Such time variability
has been reported previously for the sight lines towards HD 72089 and HD 72997
by Danks & Sembach (1995) and for HD 72127 by Hobbs et al. (1991). We have
confirmed the ongoing time variability of these spectra and present new
evidence of variability in the spectra of HD 73658, HD 74455, HD 75309 and HD
75821. We have tabulated Na I and Ca II absorption line information for the
sight lines in our sample to serve as a benchmark for further investigations of
the dynamics and evolution of the Vela SNR.Comment: 8 pages of text, 4 tables, 16 pages of figures Accepted and to be
published in ApJ
Three-dimensional hydrodynamical simulations of the large scale structure of W50-SS433
We present 3D hydrodynamical simulations of a precessing jet propagating inside a supernova remnant (SNR) shell, particularly applied to the W50-SS433 system in a search for the origin of its peculiar elongated morphology. Several runs were carried out with different values for the mass loss rate of the jet, the initial radius of the SNR, and the opening angle of the precession cone. We found that our models successfully reproduce the scale and morphology of W50 when the opening angle of the jets is set to 10 or if this angle linearly varies with time. For these models, more realistic runs were made considering that the remnant is expanding into an interstellar medium (ISM) with an exponential density profile (as HI observations suggest). Taking into account all these ingredients, the large scale morphology of the W50-SS 433 system, including the asymmetry between the lobes (formed by the jet-SNR interaction), is well reproduced.Fil: Zavala, Jesús. Universidad Nacional Autónoma de México; MéxicoFil: Velázquez, Pablo F.. Universidad Nacional Autónoma de México; MéxicoFil: Cerqueira, Adriano H. Universidade Estadual de Santa Cruz; BrasilFil: Dubner, Gloria Mabel. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentin
Ergs: The Evolution of Shell Supernova Remnants
This paper reports on a workshop hosted by the University of Minnesota, March
23-26, 1997. It addressed fundamental dynamical issues associated with the
evolution of shell supernova remnants and the relationships between supernova
remnants and their environments. The workshop considered, in addition to
classical shell SNRs, dynamical issues involving X-ray filled composite
remnants and pulsar driven shells, such as that in the Crab Nebula.
Approximately 75 participants with wide ranging interests attended the
workshop. An even larger community helped through extensive on-line debates
prior to the meeting. Each of the several sessions, organized mostly around
chronological labels, also addressed some underlying, general physical themes:
How are SNR dynamics and structures modified by the character of the CSM and
the ISM and vice versa? How are magnetic fields generated in SNRs and how do
magnetic fields influence SNRs? Where and how are cosmic-rays (electrons and
ions) produced in SNRs and how does their presence influence or reveal SNR
dynamics? How does SNR blast energy partition into various components over time
and what controls conversion between components? In lieu of a proceedings
volume, we present here a synopsis of the workshop in the form of brief
summaries of the workshop sessions. The sharpest impressions from the workshop
were the crucial and under-appreciated roles that environments have on SNR
appearance and dynamics and the critical need for broad-based studies to
understand these beautiful, but enigmatic objects. \\Comment: 54 pages text, no figures, Latex (aasms4.sty). submitted to the PAS
Focused Ion Beam Fabrication
Contains summary of research program and reports on four research projects.Charles Stark Draper Laboratory (Contract DL-H-225270)Hughes Research LaboratoriesInternational Business Machines, Inc. (Contract 456614)Nippon Telegraph and Telephone, Inc.U.S. Navy - Office of Naval Research (Contract N00014-84-K-0073)U.S. Department of Defense (Contract MDA903-85-C-0215)Hitachi Central Research Laborator
Pressure pain thresholds fluctuate with, but do not usefully predict, the clinical course of painful temporomandibular disorder
Central sensitization elicits pain hypersensitivity and is thought to be causally implicated in painful temporomandibular disorder (TMD). This causal inference is based on cross-sectional evidence that people with TMD have greater sensitivity than controls to noxious stimuli. We tested this inference in the OPPERA prospective cohort study of 3,258 adults with no lifetime history of TMD when enrolled (Visit 1). During five years of follow-up, one group labelled “persistent TMD cases” (n=72) developed first-onset TMD by Visit 2 that persisted ≥6 months until Visit 3. Another group labelled “transient TMD cases” (n=75) developed first-onset TMD at Visit 2 which resolved by Visit 3. Randomly sampled “controls” (n=126) remained TMD-free throughout all three visits. At each visit, pressure pain thresholds (PPTs) were measured by algometry at 10 cranial and bodily sites. In persistent TMD cases, mean PPTs reduced 43 kPa (P<0.0001) between Visits 1 and 2 and thereafter did not change significantly. In transient TMD cases, mean PPTs reduced 41 kPa (P<0.001) between Visits 1 and 2, and then increased 20 kPa (P<0.001) by Visit 3. These patterns were similar after excluding cranial sites symptomatic for TMD. Importantly, Visit 1 PPTs had no clinically useful prognostic value in predicting first-onset TMD (odds ratio [OR] 1.07, P=0.15). Among first-onset cases, Visit 2 PPTs were modest predictors of persistent TMD (OR=1=.36, P=0.002). In this longitudinal study, PPTs reduced when TMD developed then rebounded when TMD resolved. However, pre-morbid PPTs poorly predicted TMD incidence, countering the hypothesis that they signify mechanisms causing first-onset TMD
EHRA expert consensus document on the management of arrhythmias in frailty syndrome, endorsed by the Heart Rhythm Society (HRS), Asia Pacific Heart Rhythm Society (APHRS), Latin America Heart Rhythm Society (LAHRS), and Cardiac Arrhythmia Society of Southern Africa (CASSA)
There is an increasing proportion of the general population surviving to old age with significant chronic disease, multimorbidity, and disability. The prevalence of pre-frail state and frailty syndrome increases exponentially with advancing age and is associated with greater morbidity, disability, hospitalization, institutionalization, mortality, and health care resource use. Frailty represents a global problem, making early identification, evaluation, and treatment to prevent the cascade of events leading from functional decline to disability and death, one of the challenges of geriatric and general medicine. Cardiac arrhythmias are common in advancing age, chronic illness, and frailty and include a broad spectrum of rhythm and conduction abnormalities. However, no systematic studies or recommendations on the management of arrhythmias are available specifically for the elderly and frail population, and the uptake of many effective antiarrhythmic therapies in these patients remains the slowest. This European Heart Rhythm Association (EHRA) consensus document focuses on the biology of frailty, common comorbidities, and methods of assessing frailty, in respect to a specific issue of arrhythmias and conduction disease, provide evidence base advice on the management of arrhythmias in patients with frailty syndrome, and identifies knowledge gaps and directions for future research
Evolution of antithrombotic therapy for patients with atrial fibrillation:The prospective global GLORIA-AF registry program
OBJECTIVE: To assess baseline characteristics and antithrombotic treatment (ATT) prescription patterns in patients enrolled in the third phase of the GLORIA-AF Registry Program, evaluate predictors of treatment prescription, and compare results with phase II. METHODS: GLORIA-AF is a large, global, prospective registry program, enrolling patients with newly diagnosed nonvalvular atrial fibrillation (AF) at risk of stroke. Patients receiving dabigatran were followed for two years in phase II, and all patients were followed for 3 years in phase III. Phase II started when dabigatran became available; phase III started when the characteristics of patients receiving dabigatran became roughly comparable with those receiving vitamin K antagonists (VKAs). RESULTS: Between 2014 and 2016, 21,241 patients were enrolled in phase III. In total, 82% of patients were prescribed oral anticoagulation ([OAC]; 59.5% novel/nonvitamin K oral anticoagulants [NOACs], 22.7% VKAs). A further 11% of patients were prescribed antiplatelets without OAC and 7% were prescribed no ATT. A high stroke risk was the main driver of OAC prescription. Factors associated with prescription of VKA over NOAC included type of site, region, physician specialty, and impaired kidney function. CONCLUSION: Over the past few years, data from phase III of GLORIA-AF show that OACs have become the standard treatment option, with most newly diagnosed AF patients prescribed a NOAC. However, in some regions a remarkable proportion of patients remain undertreated. In comparison with phase II, more patients received NOACs in phase III while the prescription of VKA decreased. VKAs were preferred over NOACs in patients with impaired kidney function
The Relation Between the Surface Brightness and the Diameter for Galactic Supernova Remnants
In this work, we have constructed a relation between the surface brightness
() and diameter (D) of Galactic C- and S-type supernova remnants
(SNRs). In order to calibrate the -D dependence, we have carefully
examined some intrinsic (e.g. explosion energy) and extrinsic (e.g. density of
the ambient medium) properties of the remnants and, taking into account also
the distance values given in the literature, we have adopted distances for some
of the SNRs which have relatively more reliable distance values. These
calibrator SNRs are all C- and S-type SNRs, i.e. F-type SNRs (and S-type SNR
Cas A which has an exceptionally high surface brightness) are excluded. The
Sigma-D relation has 2 slopes with a turning point at D=36.5 pc: (at 1
GHz)=8.4 D
WmHzster (for
WmHzster and D36.5 pc) and (at 1
GHz)=2.7 10 D
WmHzster (for
WmHzster and D36.5 pc). We discussed the theoretical
basis for the -D dependence and particularly the reasons for the change
in slope of the relation were stated. Added to this, we have shown the
dependence between the radio luminosity and the diameter which seems to have a
slope close to zero up to about D=36.5 pc. We have also adopted distance and
diameter values for all of the observed Galactic SNRs by examining all the
available distance values presented in the literature together with the
distances found from our -D relation.Comment: 45 pages, 2 figures, accepted for publication in Astronomical and
Astrophysical Transaction
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