56 research outputs found
Willingness to act upon beliefs about 'treatment as prevention' among Australian gay and bisexual men
HIV 'treatment as prevention' (TasP) is highly effective in reducing HIV transmission in serodiscordant couples. There has been little examination of gay and bisexual men's attitudes towards TasP, particularly regarding men's willingness to act on beliefs about TasP. We conducted an online cross-sectional survey of Australian men in late 2012 to investigate knowledge and beliefs about new developments in HIV prevention. Amongst 839 men (mean age 39.5 years), men tended to disagree that TasP was sufficiently effective to justify reduced condom use, although HIV-positive men had more favourable attitudes. Only a minority of men were aware of any evidence for TasP; and one-quarter incorrectly believed that evidence for the effectiveness of TasP already existed for the homosexual population. One-fifth (20.5%) of men reported that they would be willing to have condomless anal intercourse with an opposite-status sexual partner when the HIV-positive partner was taking HIV treatments. Factors independently associated with such willingness were: HIV-positive serostatus, reporting any serodiscordant or serononconcordant condomless anal intercourse with a regular male partner in the previous six months, reporting any condomless anal intercourse with a casual male partner in the previous six months, and having greater beliefs in the effectiveness of TasP. This indicated that the men most willing to rely on TasP to prevent transmission were already engaging in higher risk practices. Biomedical HIV prevention represents a rapidly changing environment with new research as well as community and policy responses emerging at a fast pace. For men with serodiscordant sexual partners to successfully apply TasP to reducing transmission risk, more support and education is needed to enable better utilisation of TasP in specific relational and sexual contexts
Swift follow-up observations of candidate gravitational-wave transient events
We present the first multi-wavelength follow-up observations of two candidate
gravitational-wave (GW) transient events recorded by LIGO and Virgo in their
2009-2010 science run. The events were selected with low latency by the network
of GW detectors and their candidate sky locations were observed by the Swift
observatory. Image transient detection was used to analyze the collected
electromagnetic data, which were found to be consistent with background.
Off-line analysis of the GW data alone has also established that the selected
GW events show no evidence of an astrophysical origin; one of them is
consistent with background and the other one was a test, part of a "blind
injection challenge". With this work we demonstrate the feasibility of rapid
follow-ups of GW transients and establish the sensitivity improvement joint
electromagnetic and GW observations could bring. This is a first step toward an
electromagnetic follow-up program in the regime of routine detections with the
advanced GW instruments expected within this decade. In that regime
multi-wavelength observations will play a significant role in completing the
astrophysical identification of GW sources. We present the methods and results
from this first combined analysis and discuss its implications in terms of
sensitivity for the present and future instruments.Comment: Submitted for publication 2012 May 25, accepted 2012 October 25,
published 2012 November 21, in ApJS, 203, 28 (
http://stacks.iop.org/0067-0049/203/28 ); 14 pages, 3 figures, 6 tables;
LIGO-P1100038; Science summary at
http://www.ligo.org/science/Publication-S6LVSwift/index.php ; Public access
area to figures, tables at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p110003
Search for gravitational waves associated with the InterPlanetary Network short gamma ray bursts
We outline the scientific motivation behind a search for gravitational waves
associated with short gamma ray bursts detected by the InterPlanetary Network
(IPN) during LIGO's fifth science run and Virgo's first science run. The IPN
localisation of short gamma ray bursts is limited to extended error boxes of
different shapes and sizes and a search on these error boxes poses a series of
challenges for data analysis. We will discuss these challenges and outline the
methods to optimise the search over these error boxes.Comment: Methods paper; Proceedings for Eduardo Amaldi 9 Conference on
Gravitational Waves, July 2011, Cardiff, U
First Low-Latency LIGO+Virgo Search for Binary Inspirals and their Electromagnetic Counterparts
Aims. The detection and measurement of gravitational-waves from coalescing
neutron-star binary systems is an important science goal for ground-based
gravitational-wave detectors. In addition to emitting gravitational-waves at
frequencies that span the most sensitive bands of the LIGO and Virgo detectors,
these sources are also amongst the most likely to produce an electromagnetic
counterpart to the gravitational-wave emission. A joint detection of the
gravitational-wave and electromagnetic signals would provide a powerful new
probe for astronomy.
Methods. During the period between September 19 and October 20, 2010, the
first low-latency search for gravitational-waves from binary inspirals in LIGO
and Virgo data was conducted. The resulting triggers were sent to
electromagnetic observatories for followup. We describe the generation and
processing of the low-latency gravitational-wave triggers. The results of the
electromagnetic image analysis will be described elsewhere.
Results. Over the course of the science run, three gravitational-wave
triggers passed all of the low-latency selection cuts. Of these, one was
followed up by several of our observational partners. Analysis of the
gravitational-wave data leads to an estimated false alarm rate of once every
6.4 days, falling far short of the requirement for a detection based solely on
gravitational-wave data.Comment: 13 pages, 13 figures. For a repository of data used in the
publication, go to:
http://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=P1100065 Also see the
announcement for this paper on ligo.org at:
http://www.ligo.org/science/Publication-S6CBCLowLatency
A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007
We present the results of the first search for gravitational wave bursts
associated with high energy neutrinos. Together, these messengers could reveal
new, hidden sources that are not observed by conventional photon astronomy,
particularly at high energy. Our search uses neutrinos detected by the
underwater neutrino telescope ANTARES in its 5 line configuration during the
period January - September 2007, which coincided with the fifth and first
science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed
for candidate gravitational-wave signals coincident in time and direction with
the neutrino events. No significant coincident events were observed. We place
limits on the density of joint high energy neutrino - gravitational wave
emission events in the local universe, and compare them with densities of
merger and core-collapse events.Comment: 19 pages, 8 figures, science summary page at
http://www.ligo.org/science/Publication-S5LV_ANTARES/index.php. Public access
area to figures, tables at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120000
Upper limits on a stochastic gravitational-wave background using LIGO and Virgo interferometers at 600-1000 Hz
A stochastic background of gravitational waves is expected to arise from a
superposition of many incoherent sources of gravitational waves, of either
cosmological or astrophysical origin. This background is a target for the
current generation of ground-based detectors. In this article we present the
first joint search for a stochastic background using data from the LIGO and
Virgo interferometers. In a frequency band of 600-1000 Hz, we obtained a 95%
upper limit on the amplitude of , of , assuming a value of the Hubble parameter
of . These new limits are a factor of seven better than the
previous best in this frequency band.Comment: 29 pages, 6 figures. For a repository of data used in the
publication, please see
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=22210. Also see the
announcement for this paper at
http://www.ligo.org/science/Publication-S5VSR1StochIso
Einstein@Home all-sky search for periodic gravitational waves in LIGO S5 data
This paper presents results of an all-sky searches for periodic gravitational
waves in the frequency range [50, 1190] Hz and with frequency derivative ranges
of [-2 x 10^-9, 1.1 x 10^-10] Hz/s for the fifth LIGO science run (S5). The
novelty of the search lies in the use of a non-coherent technique based on the
Hough-transform to combine the information from coherent searches on timescales
of about one day. Because these searches are very computationally intensive,
they have been deployed on the Einstein@Home distributed computing project
infrastructure. The search presented here is about a factor 3 more sensitive
than the previous Einstein@Home search in early S5 LIGO data. The
post-processing has left us with eight surviving candidates. We show that
deeper follow-up studies rule each of them out. Hence, since no statistically
significant gravitational wave signals have been detected, we report upper
limits on the intrinsic gravitational wave amplitude h0. For example, in the
0.5 Hz-wide band at 152.5 Hz, we can exclude the presence of signals with h0
greater than 7.6 x 10^-25 with a 90% confidence level.Comment: 29 pages, 14 figures, 6 tables. Science summary page at
http://www.ligo.org/science/Publication-FullS5EatH/index.php ; Public access
area to figures and tables at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120002
The characterization of Virgo data and its impact on gravitational-wave searches
Between 2007 and 2010 Virgo collected data in coincidence with the LIGO and
GEO gravitational-wave (GW) detectors. These data have been searched for GWs
emitted by cataclysmic phenomena in the universe, by non-axisymmetric rotating
neutron stars or from a stochastic background in the frequency band of the
detectors. The sensitivity of GW searches is limited by noise produced by the
detector or its environment. It is therefore crucial to characterize the
various noise sources in a GW detector. This paper reviews the Virgo detector
noise sources, noise propagation, and conversion mechanisms which were
identified in the three first Virgo observing runs. In many cases, these
investigations allowed us to mitigate noise sources in the detector, or to
selectively flag noise events and discard them from the data. We present
examples from the joint LIGO-GEO-Virgo GW searches to show how well noise
transients and narrow spectral lines have been identified and excluded from the
Virgo data. We also discuss how detector characterization can improve the
astrophysical reach of gravitational-wave searches.Comment: 50 pages, 12 figures, 5 table
Search for Gravitational Waves from Intermediate Mass Binary Black Holes
We present the results of a weakly modeled burst search for gravitational
waves from mergers of non-spinning intermediate mass black holes (IMBH) in the
total mass range 100--450 solar masses and with the component mass ratios
between 1:1 and 4:1. The search was conducted on data collected by the LIGO and
Virgo detectors between November of 2005 and October of 2007. No plausible
signals were observed by the search which constrains the astrophysical rates of
the IMBH mergers as a function of the component masses. In the most efficiently
detected bin centered on 88+88 solar masses, for non-spinning sources, the rate
density upper limit is 0.13 per Mpc^3 per Myr at the 90% confidence level.Comment: 13 pages, 4 figures: data for plots and archived public version at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=62326, see also the
public announcement at http://www.ligo.org/science/Publication-S5IMBH
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