315 research outputs found
An upper-limit on the linear polarization fraction of the GW170817 radio continuum
We present late-time radio observations of GW170817, the first binary neutron
star merger discovered through gravitational waves by the advanced LIGO and
Virgo detectors. Our observations, carried out with the Karl G. Jansky Very
Large Array, were optimized to detect polarized radio emission, and thus to
constrain the linear polarization fraction of GW170817. At an epoch of ~244
days after the merger, we rule out linearly polarized emission above a fraction
of ~12% at a frequency of 2.8 GHz (99% confidence). Within the structured jet
scenario (a.k.a. successful jet plus cocoon system) for GW170817, the derived
upper-limit on the radio continuum linear polarization fraction strongly
constrains the magnetic field configuration in the shocked ejecta. We show that
our results for GW170817 are compatible with the low level of linear
polarization found in afterglows of cosmological long gamma-ray bursts.
Finally, we discuss our findings in the context of future expectations for the
study of radio counterparts of binary neutron star mergers identified by
ground-based gravitational-wave detectors.Comment: 5 pages, 2 figures, 1 tabl
Constraining properties of neutron star merger outflows with radio observations
The jet opening angle and inclination of GW170817 -- the first detected
binary neutron star merger -- were vital to understand its energetics, relation
to short gamma-ray bursts, and refinement of the standard siren-based
determination of the Hubble constant, . These basic quantities were
determined through a combination of the radio lightcurve and Very Long Baseline
Interferometry (VLBI) measurements of proper motion. In this paper we discuss
and quantify the prospects for the use of radio VLBI observations and
observations of scintillation-induced variability to measure the source size
and proper motion of merger afterglows, and thereby infer properties of the
merger including inclination angle, opening angle and energetics. We show that
these techniques are complementary as they probe different parts of the
circum-merger density/inclination angle parameter space and different periods
of the temporal evolution of the afterglow. We also find that while VLBI
observations will be limited to the very closest events it will be possible to
detect scintillation for a large fraction of events beyond the range of current
gravitational wave detectors. Scintillation will also be detectable with next
generation telescopes such as the Square Kilometre Array, 2000 antenna Deep
Synoptic Array and the next generation Very Large Array, for a large fraction
of events detected with third generation gravitational wave detectors. Finally,
we discuss prospects for the measurement of the with VLBI observations of
neutron star mergers and compare this technique to other standard siren
methods
Digital and remote behavioral therapies for treating tic disorders: Recent advances and next steps
The rapid expansion of access to and engagement with digital technology over the past 15 years has transformed the potential for remote delivery of evidence-based digital health interventions (DHIs). Digital and remote behavioral interventions have the potential to address current gaps in the provision of evidence-based therapies in healthcare services. As the lack of access to behavioral treatments for people with tic disorders is a pressing issue across the world, there is great potential for DHIs to close this treatment gap. Here, we present a critical synthesis of the recent key advances in the field of digitally delivered, remote therapy for tics, outlining the research evidence for the clinical and cost-effectiveness and acceptability of digital or remotely delivered therapy. We found five trials aimed at reducing tic severity in children and young people and one trial for adults. The evidence supports the clinical utility of DHIs to deliver tic therapies, which shows promise in being clinically efficacious compared to an active control. Furthermore, DHIs in trials show good adherence and engagement and are acceptable to patients. The role of human support (including therapists and parents for young people) is likely to be important to encourage adherence. DHIs, where the main therapeutic content is delivered via web-based chapters, are likely to reduce clinical time, and maintain intervention fidelity, but further research is required to understand cost-effectiveness. Despite utilizing randomized controlled trials, only two trials were sufficiently powered to address efficacy and only one trial explored contextual factors that may influence engagement. Moreover, only one trial followed patients for >12 months, thus further long-term follow-ups are required. Specifically, we note that despite an emerging evidence base, DHIs for tics are yet to be routinely implemented in healthcare provision in any country. Drawing on the existing evidence, we conclude by proposing a stepped care model, in which digital therapy is implemented as a widely accessible first-line treatment using a purely online or therapist-supported approach
A matched-filter approach to radio variability and transients: searching for orphan afterglows in the VAST Pilot Survey
Radio transient searches using traditional variability metrics struggle to
recover sources whose evolution timescale is significantly longer than the
survey cadence. Motivated by the recent observations of slowly evolving radio
afterglows at gigahertz frequency, we present the results of a search for radio
variables and transients using an alternative matched-filter approach. We
designed our matched-filter to recover sources with radio light curves that
have a high-significance fit to power-law and smoothly broken power-law
functions; light curves following these functions are characteristic of
synchrotron transients, including "orphan" gamma-ray burst afterglows, which
were the primary targets of our search. Applying this matched-filter approach
to data from Variables and Slow Transients Pilot Survey conducted using the
Australian SKA Pathfinder, we produced five candidates in our search.
Subsequent Australia Telescope Compact Array observations and analysis revealed
that: one is likely a synchrotron transient; one is likely a flaring active
galactic nucleus, exhibiting a flat-to-steep spectral transition over
months; one is associated with a starburst galaxy, with the radio emission
originating from either star formation or an underlying slowly-evolving
transient; and the remaining two are likely extrinsic variables caused by
interstellar scintillation. The synchrotron transient, VAST J175036.1181454,
has a multi-frequency light curve, peak spectral luminosity and volumetric rate
that is consistent with both an off-axis afterglow and an off-axis tidal
disruption event; interpreted as an off-axis afterglow would imply an average
inverse beaming factor , or equivalently, an average jet opening angle of deg.Comment: 20 pages, 6 figures; accepted for publication in MNRA
Batf3-Dependent CD11blow/− Peripheral Dendritic Cells Are GM-CSF-Independent and Are Not Required for Th Cell Priming after Subcutaneous Immunization
Dendritic cells (DCs) subsets differ in precursor cell of origin, functional properties, requirements for growth factors, and dependence on transcription factors. Lymphoid-tissue resident CD8α+ conventional DCs (cDCs) and CD11blow/−CD103+ non-lymphoid DCs are developmentally related, each being dependent on FMS-like tyrosine kinase 3 ligand (Flt3L), and requiring the transcription factors Batf3, Irf8, and Id2 for development. It was recently suggested that granulocyte/macrophage colony stimulating factor (GM-CSF) was required for the development of dermal CD11blow/−Langerin+CD103+ DCs, and that this dermal DC subset was required for priming autoreactive T cells in experimental autoimmune encephalitis (EAE). Here, we compared development of peripheral tissue DCs and susceptibility to EAE in GM-CSF receptor deficient (Csf2rb−/−) and Batf3−/− mice. We find that Batf3-dependent dermal CD11blow/−Langerin+ DCs do develop in Csf2rb−/− mice, but that they express reduced, but not absent, levels of CD103. Further, Batf3−/− mice lacking all peripheral CD11blow/− DCs show robust Th cell priming after subcutaneous immunization and are susceptible to EAE. Our results suggest that defective T effector priming and resistance to EAE exhibited by Csf2rb−/− mice does not result from the absence of dermal CD11blow/−Langerin+CD103+ DCs
The Grizzly, September 1, 1989
U.C. Transition • Diverse Freshman Diverge on Ursinus • Letter: Frosh Finds Staff Discourteous • Corson Facelift Removes Moles • Bright Moments Jazz Steams Bomberger Night • Bio Grants Lend Expansion • Lax: National Champs! • Wood Takes Titles • Lacrosse Coaches Retire • Lady Bears: Few, But Strong • Bears to Repeat • St. Joe\u27s / U.C. MBA Still O.K. • Academic Year Openedhttps://digitalcommons.ursinus.edu/grizzlynews/1238/thumbnail.jp
Periodic Radio Emission from the T8 Dwarf WISE J062309.94-045624.6
We present the detection of rotationally modulated, circularly polarized
radio emission from the T8 brown dwarf WISE J062309.94-045624.6 between 0.9 and
2.0 GHz. We detected this high proper motion ultracool dwarf with the
Australian SKA Pathfinder in GHz imaging data from the Rapid ASKAP
Continuum Survey. We observed WISE J062309.94-045624.6 to have a time and
frequency averaged Stokes I flux density of mJy beam, with
an absolute circular polarization fraction of , and calculated a
specific radio luminosity of erg s Hz. In
follow-up observations with the Australian Telescope Compact Array and MeerKAT
we identified a multi-peaked pulse structure, used dynamic spectra to place a
lower limit of kG on the dwarf's magnetic field, and measured a
h periodicity which we concluded to be due to rotational
modulation. The luminosity and period we measured are comparable to those of
other ultracool dwarfs observed at radio wavelengths. This implies that future
megahertz to gigahertz surveys, with increased cadence and improved
sensitivity, are likely to detect similar or later-type dwarfs. Our detection
of WISE J062309.94-045624.6 makes this dwarf the coolest and latest-type star
observed to produce radio emission.Comment: Accepted for publication in ApJ Letters; 11 pages, 3 figures and 2
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