7,319 research outputs found
Constraining H0 from Chandra Observations of Q0957+561
We report the detection of the lens cluster of the gravitational lens (GL)
system Q0957+561 from a deep observation with the Advanced CCD Imaging
Spectrometer on-board the Chandra X-ray Observatory. Intracluster X-ray
emission is found to be centered 4.3 +/- 1.3 arcsec east and 3.5(-0.6,+1.3)
arcsec north of image B, nearer than previous estimates. Its spectrum can be
modeled well with a thermal plasma model consistent with the emission
originating from a cluster at a redshift of 0.36. Our best-fit estimates of the
cluster temperature of T_e = 2.09(-0.54,+0.83) keV (90 percent confidence) and
mass distribution of the cluster are used to derive the convergence parameter
kappa, the ratio of the cluster surface mass density to the critical density
required for lensing. We estimate the convergence parameter at the location of
the lensed images A and B to be kappa_A = 0.22(+0.14,-0.07) and kappa_B =
0.21(+0.12,-0.07), respectively (90 percent confidence levels). The observed
cluster center, mass distribution and convergence parameter kappa provide
additional constraints to lens models of this system. Our new results break a
mass-sheet degeneracy in GL models of this system and provide better
constraints of ~ 29 percent (90 percent confidence levels) on the Hubble
constant. We also present results from the detection of the most distant X-ray
jet (z = 1.41) detected to date. The jet extends approximately 8 arcsec NE of
image A and three knots are resolved along the X-ray jet with flux densities
decreasing with distance from the core. The observed radio and optical flux
densities of the knots are fitted well with a synchrotron model and the X-ray
emission is modeled well with inverse Compton scattering of Cosmic Microwave
Background photons by synchrotron-emitting electrons in the jet.Comment: 18 pages, includes 7 figures, Accepted for publication in Ap
Boosting jet power in black hole spacetimes
The extraction of rotational energy from a spinning black hole via the
Blandford-Znajek mechanism has long been understood as an important component
in models to explain energetic jets from compact astrophysical sources. Here we
show more generally that the kinetic energy of the black hole, both rotational
and translational, can be tapped, thereby producing even more luminous jets
powered by the interaction of the black hole with its surrounding plasma. We
study the resulting Poynting jet that arises from single boosted black holes
and binary black hole systems. In the latter case, we find that increasing the
orbital angular momenta of the system and/or the spins of the individual black
holes results in an enhanced Poynting flux.Comment: 7 pages, 5 figure
Public, animal, and environmental health implications of aquaculture.
Aquaculture is important to the United States and the world's fishery system. Both import and export markets for aquaculture products will expand and increase as research begins to remove physiologic and other animal husbandry barriers. Overfishing of wild stock will necessitate supplementation and replenishment through aquaculture. The aquaculture industry must have a better understanding of the impact of the "shrouded" public and animal health issues: technology ignorance, abuse, and neglect. Cross-pollination and cross-training of public health and aquaculture personnel in the effect of public health, animal health, and environmental health on aquaculture are also needed. Future aquaculture development programs require an integrated Gestalt public health approach to ensure that aquaculture does not cause unacceptable risks to public or environmental health and negate the potential economic and nutritional benefits of aquaculture
Six Dimensions of Expertise: A More Comprehensive Definition of Cognitive Expertise For Team Coordination
Looking at expertise from the vantage point of many knowledge domains allows the observations and resulting definitions to be useful across a broad range of subject areas. A stable set of definitions that work on a higher, more comprehensive level than the current literature offers is needed for an integrated description of expertise. A cohesive cross-domain definition and explanation of expertise can be used to optimise group interactions. Since group performance incorporates additional components of expertise that are not present in individual performance situations, these additional components must be examined in order to see a full picture of the successful utilisation of expertise in a group setting. This expanded expertise definition will allow group dynamics to be better understood and will help break down the expertise components required to have successful group interactions
Remarks on monopole charge properties within the Generalized Coherent State Model
The Generalized Coherent State Model, proposed previously for a unified
description of magnetic and electric collective properties of nuclear systems,
is used to study the ground state band charge density as well as the E0
transitions from to . The influence of the nuclear
deformation and of angular momentum projection on the charge density is
investigated. The monopole transition amplitude has been calculated for ten
nuclei. The results are compared with some previous theoretical studies and
with the available experimental data. Our results concerning angular momentum
projection are consistent with those of previous microscopic calculations for
the ground state density. The calculations for the E0 transitions agree quite
well with the experimental data. Issues like how the shape transitions or shape
coexistence are reflected in the behavior are also addressed.Comment: 32 pages, 7 figure
Perceived Ability to Treat Opioid Use Disorder in West Virginia
Introduction: Medication-assisted treatment (MAT) is an evidence-based therapy for opioid use disorder (OUD) that has not been fully implemented in rural areas due to patient, provider, and logistical barriers. Limited information is available on provider perceptions of barriers to MAT in rural Central Appalachia which has very high rates of OUD compared to the rest the United States.
Purpose: Determine perceived barriers for potential prescribers to using MAT, including buprenorphine, as part of treatment for OUD in West Virginia.
Methods: A 30-question, anonymous survey was sent to physicians, physician assistants and advanced practice registered nurses using an online link. Link was distributed through the WV Medicaid provider list, professional association and institutional contact lists, and social media. Comparisons were made by provider waivered or non-waivered status.
Results: Overall, 84% of waivered providers (n = 77) and only 8% of non-waivered providers (n = 341) indicated ever prescribing a form of MAT for OUD; 73% percent of waivered providers were currently prescribing MAT and accepting new patients with OUD. Only 4% of non-waivered providers were currently prescribing MAT and 21% were currently accepting new patients with OUD. Lack of available mental health and psychosocial support services and concerns about diversion or misuse of medication were the top perceived barriers to implementing MAT programs.
Implications: Implementing strategies to improve access to behavioral health care including telehealth and apps, provider training and addressing stigma around OUD treatment were identified as priorities that would help increase providers’ willingness to prescribe medications for OUD treatment
The Anderson-Mott transition induced by hole-doping in Nd1-xTiO3
The insulator/metal transition induced by hole-doping due to neodymium
vacancies of the Mott- Hubbard antiferromagnetic insulator, Nd1-xTiO3, is
studied over the composition range 0.010(6) < x < 0.243(10). Insulating p-types
conduction is found for x < 0.071(10). Anderson localization in the presence of
a Mott-Hubbard gap, is the dominant localization mechanism for the range of
0.074(10) < x < 0.089(1) samples. For x < 0.089(1), n-type conduction is
observed and the activation energy extrapolates to zero by x < 0.1. The
0.095(8) < x < 0.203(10) samples are Fermi-liquid metals and the effects of
strong electronic correlations are evident near the metal-to-insulator
boundaries in features such as large Fermi liquid T2 coefficients. For 0.074(9)
< x < 0.112(4), a weak negative magnetoresistance is found below ~ 15 K and it
is attributed to the interaction of conduction electrons with Nd3+ magnetic
moments. Combining information from our companion study of the magnetic
properties of Nd1-xTiO3 solid solution, a phase diagram is proposed. The main
conclusions are that long range antiferromagnetic order disappears before the
onset of metallic behavior and that the Anderson-Mott transition occurs over a
finite range of doping levels. Our results differ from conclusions drawn from a
similar study on the hole doped Nd1-xCaxTiO3 system which found the
co-existence of antiferromagnetic order and metallic behavior and that the Mott
transition occurs at a discrete doping level
First e-VLBI observations of GRS 1915+105
We present results from the first successful open call e-VLBI science run,
observing the X-ray binary GRS 1915+105. e-VLBI science allows the rapid
production of VLBI radio maps, within hours of an observation rather than
weeks, facilitating a decision for follow-up observations. A total of 6
telescopes observing at 5 GHz across the European VLBI Network (EVN) were
correlated in real time at the Joint Institute for VLBI in Europe (JIVE).
Constant data rates of 128 Mbps were transferred from each telescope, giving 4
TB of raw sampled data over the 12 hours of the whole experiment. Throughout
this, GRS 1915+105 was observed for a total of 5.5 hours, producing 2.8 GB of
visibilities of correlated data. A weak flare occurred during our observations,
and we detected a slightly resolved component of 2.7 x 1.2 milliarcsecond with
a position angle of 140 (+/-2) degrees. The peak brightness was 10.2 mJy per
beam, with a total integrated radio flux of 11.1 mJy.Comment: Accepted for publication in MNRAS 4 pages, 3 figure
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