2,453 research outputs found
The Pattern Of The World
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93544/1/j.1467-9736.2012.00830.x.pd
Pietro Cavallini and The Ruins of Rome
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73239/1/j.0044-0124.2004.00773.x.pd
My War
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112277/1/yrev.12073.pd
Polarized synchrotron emission in quiescent black hole X-ray transients
We present near-infrared polarimetric observations of the black hole X-ray
binaries Swift J1357.2-0933 and A0620-00. In both sources, recent studies have
demonstrated the presence of variable infrared synchrotron emission in
quiescence, most likely from weak compact jets. For Swift J1357.2-0933 we find
that the synchrotron emission is polarized at a level of 8.0 +- 2.5 per cent (a
3.2 sigma detection of intrinsic polarization). The mean magnitude and rms
variability of the flux (fractional rms of 19-24 per cent in K_s-band) agree
with previous observations. These properties imply a continuously launched
(stable on long timescales), highly variable (on short timescales) jet in the
Swift J1357.2-0933 system in quiescence, which has a moderately tangled
magnetic field close to the base of the jet. We find that for A0620-00, there
are likely to be three components to the optical-infrared polarization;
interstellar dust along the line of sight, scattering within the system, and an
additional source that changes the polarization position angle in the reddest
(H and K_s) wave-bands. We interpret this as a stronger contribution of
synchrotron emission, and by subtracting the line-of-sight polarization, we
measure an excess of ~ 1.25 +- 0.28 per cent polarization and a position angle
of the magnetic field vector that is consistent with being parallel with the
axis of the resolved radio jet. These results imply that weak jets in low
luminosity accreting systems have magnetic fields which possess similarly
tangled fields compared to the more luminous, hard state jets in X-ray
binaries.Comment: Accepted to MNRA
Urotensin II in cardiovascular regulation
Cardiovascular function is modulated by neuronal transmitters, circulating hormones, and factors that are released locally from tissues. Urotensin II (UII) is an 11 amino acid peptide that stimulates its’ obligatory G protein coupled urotensin II receptors (UT) to modulate cardiovascular function in humans and in other animal species, and has been implicated in both vasculoprotective and vasculopathic effects. For example, tissue and circulating concentrations of UII have been reported to increase in some studies involving patients with atherosclerosis, heart failure, hypertension, preeclampsia, diabetes, renal disease and liver disease, raising the possibility that the UT receptor system is involved in the development and/or progression of these conditions. Consistent with this hypothesis, administration of UT receptor antagonists to animal models of cardiovascular disease have revealed improvements in cardiovascular remodelling and hemodynamics. However, recent studies have questioned this contributory role of UII in disease, and have instead postulated a protective effect on the cardiovascular system. For example, high concentrations of circulating UII correlated with improved clinical outcomes in patients with renal disease or myocardial infarction. The purpose of this review is to consider the regulation of the cardiovascular system by UII, giving consideration to methodologies for measurement of plasma concentrations, sites of synthesis and triggers for release
Robotic Astronomy with the Faulkes Telescopes and Las Cumbres Observatory Global Telescope
We present results from ongoing science projects conducted by members of the
Faulkes Telescope (FT) team and Las Cumbres Observatory Global Telescope
(LCOGT). Many of these projects incorporate observations carried out and
analysed by FT users, comprising amateur astronomers and schools.
We also discuss plans for the further development of the LCOGT network.Comment: 8 pages, 2 figures, conference proceedings from "Workshop on Robotic
Autonomous Observatories", held at Malaga, Spain from 18-21 May 2009,
acccepted for publication in Advances in Astronom
Continued monitoring of LMXBs with the Faulkes Telescopes
The Faulkes Telescope Project is an educational and research arm of the Las Cumbres Observatory Global Telescope Network (LCOGTN). It has two 2-metre robotic telescopes, located at Haleakala on Maui (FT North) and Siding Spring in Australia (FT South). It is planned for these telescopes to be complemented by a research network of eighteen 1-metre telescopes, along with an educational network of twenty-eight 0.4-metre telescopes, providing 24 hour coverage of both northern and southern hemispheres.
We have been conducting a monitoring project of 13 low-mass X-ray binaries (LMXBs) using FT North since early 2006. The introduction of FT South has allowed us to extend this to monitor a total of 30 LMXBs (see target list, Section 4). New instrumentation will allow us to expand this project to include both infrared wavelengths (z and y band) and spectroscopy. Brighter targets (~ 16 - 18 mag.) are imaged weekly in V, R and i’ bands (SNR ~ 50), while fainter ones (> 18 mag.) are observed only in i’ band (SNR ~ 20). We alter this cadence in response to our own analysis or Astronomers Telegrams (ATels)
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