41 research outputs found
All-sky search for continuous gravitational waves from isolated neutron stars using Advanced LIGO O2 data
© 2019 American Physical Society. We present results of an all-sky search for continuous gravitational waves (CWs), which can be produced by fast spinning neutron stars with an asymmetry around their rotation axis, using data from the second observing run of the Advanced LIGO detectors. Three different semicoherent methods are used to search in a gravitational-wave frequency band from 20 to 1922 Hz and a first frequency derivative from -1×10-8 to 2×10-9 Hz/s. None of these searches has found clear evidence for a CW signal, so upper limits on the gravitational-wave strain amplitude are calculated, which for this broad range in parameter space are the most sensitive ever achieved
The US Program in Ground-Based Gravitational Wave Science: Contribution from the LIGO Laboratory
Recent gravitational-wave observations from the LIGO and Virgo observatories have brought a sense of great excitement to scientists and citizens the world over. Since September 2015,10 binary black hole coalescences and one binary neutron star coalescence have been observed. They have provided remarkable, revolutionary insight into the "gravitational Universe" and have greatly extended the field of multi-messenger astronomy. At present, Advanced LIGO can see binary black hole coalescences out to redshift 0.6 and binary neutron star coalescences to redshift 0.05. This probes only a very small fraction of the volume of the observable Universe. However, current technologies can be extended to construct "3rd Generation" (3G) gravitational-wave observatories that would extend our reach to the very edge of the observable Universe. The event rates over such a large volume would be in the hundreds of thousands per year (i.e. tens per hour). Such 3G detectors would have a 10-fold improvement in strain sensitivity over the current generation of instruments, yielding signal-to-noise ratios of 1000 for events like those already seen. Several concepts are being studied for which engineering studies and reliable cost estimates will be developed in the next 5 years
Observation of gravitational waves from the coalescence of a 2.5−4.5 M⊙ compact object and a neutron star
Ultralight vector dark matter search using data from the KAGRA O3GK run
Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM
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Recruiting Black Men Who Have Sex with Men and Women (BMSMW) in an Urban Setting for HIV Prevention Research.
Concerns related to stigma and confidentiality limit HIV-related study recruitment and retention of Black men who have sex with men and women (MSMW). This paper examines lessons learned from recruitment strategies utilized in enrolling 437 participants between 2007 and 2011 for a randomized controlled trial to test a culturally specific HIV risk-reduction intervention for Black MSMW. Interested respondents completed a brief screener and participants completed surveys at baseline and at post, 3 and 6 months follow-up. Recruitment patterns were assessed by examining the source of study information reported when respondents were asked how they learned about the study. Chi-square tests were then conducted to examine differences in the distribution of participants by self-reported HIV status, age group and socio-economic status (SES) for each type of study information source. Regardless of HIV or SES, study respondents were more likely to have received information about the study through a service agency than from other sources. Participants ages 30-49 and 50+ years were most likely to have learned about the study from an agency (34.9% and 27.0%, respectively) or another participant/friend (20.1%, 23.1%) and least likely to have found out from bus (0.8%, 0.0%) or radio (1.3%, 0.0%) advertisements; whereas younger participants were more likely to have heard about the study through a friend/participant (23.4%) than an agency (15.4%). Although, 14.1% of participants' ages less than 30 years reported the Internet as their source of study information, this compared to just 2.7% and 4.8% for participants in the 30-49 and 50-plus age groups. While agencies and referrals from personal networks appear to be the most significant recruitment source for potential HIV research participants, there is evidence that Internet based tools may enhance recruitment, particularly among younger Black MSMW
Recruiting Black Men Who Have Sex with Men and Women (BMSMW) in an Urban Setting for HIV Prevention Research.
ObjectivesConcerns related to stigma and confidentiality limit HIV-related study recruitment and retention of Black men who have sex with men and women (MSMW). This paper examines lessons learned from recruitment strategies utilized in enrolling 437 participants between 2007 and 2011 for a randomized controlled trial to test a culturally specific HIV risk-reduction intervention for Black MSMW.MethodsInterested respondents completed a brief screener and participants completed surveys at baseline and at post, 3 and 6 months follow-up. Recruitment patterns were assessed by examining the source of study information reported when respondents were asked how they learned about the study. Chi-square tests were then conducted to examine differences in the distribution of participants by self-reported HIV status, age group and socio-economic status (SES) for each type of study information source.ResultsRegardless of HIV or SES, study respondents were more likely to have received information about the study through a service agency than from other sources. Participants ages 30-49 and 50+ years were most likely to have learned about the study from an agency (34.9% and 27.0%, respectively) or another participant/friend (20.1%, 23.1%) and least likely to have found out from bus (0.8%, 0.0%) or radio (1.3%, 0.0%) advertisements; whereas younger participants were more likely to have heard about the study through a friend/participant (23.4%) than an agency (15.4%). Although, 14.1% of participants' ages less than 30 years reported the Internet as their source of study information, this compared to just 2.7% and 4.8% for participants in the 30-49 and 50-plus age groups.ConclusionsWhile agencies and referrals from personal networks appear to be the most significant recruitment source for potential HIV research participants, there is evidence that Internet based tools may enhance recruitment, particularly among younger Black MSMW
Measuring Gender Role Conflict, Internalized Stigma, and Racial and Sexual Identity in Behaviorally Bisexual Black Men.
Black men who have sex with men and women (BMSMW) experience pressure to fill hypermasculine ideals and may not identify with "gay" cultural norms. Existing measures of gender role expectations and internalized homophobia are not culturally appropriate for BMSMW. Researchers generally measure categorical identification with race, gender, and sexual orientation groups separately, whereas BMSMW may identify with multiple categories. We modified the Gender Role Conflict Scale to create the M-GRCS and the Internalized Homophobia Scale to include biphobia (Internalized Bi/Homophobia Scale, IBHS). To examine identification at the intersection of race, gender, and sexual orientation, we created 11 Integrated Race and Sexuality Scale (IRSS) items. With data from 429 BMSMW, we conducted exploratory factor analysis of the 59 items using categorical principal axis factoring with unweighted least squares extraction and Promax factor rotation. We created simple-summated multi-item scales and evaluated their construct validity. The rotated solution yielded four factors with 47 items and a simple factor structure: M-GRCS defined two factors (α = .93 for restricted emotionality/affection; .87 for success/power/competition); the IBHS (α = .89) and IRSS (α = .74) each defined a single factor. The IRSS factor was positively correlated with the Lukwago Racial Pride Scale, r(417) = .40. The IBHS factor was negatively correlated with the IRSS factor, r(414) = - .22. The two M-GRCS factors suggest that the construct of hypermasculinity impacts BMSMW. The high IBHS reliability indicates that homophobia and biphobia were positively correlated in this sample. These three scales have potential for future studies with BMSMW
Efficacy of a Small-Group Intervention for Post-Incarcerated Black Men Who Have Sex with Men and Women (MSMW).
We conducted a randomized controlled trial of a six-session behavioral intervention designed to reduce frequency of condomless sex and numbers of sex partners among recently incarcerated, bisexual Black men. One hundred participants were assigned to the small-group intervention, Men in Life Environments (MILE), and 112 were assigned to the control condition. Among those assigned to MILE, 69% attended at least one session, 88% of whom attended all sessions. At 3-months' follow-up, large reductions in risk behaviors were reported by both groups. Means for episodes of condomless sex in the previous 3 months declined from 27.7 to 8.0 for the intervention and 25.6 to 6.7 for the control group. Reductions were not greater for the intervention than those of the control group. Regression to the mean, respondent burden, and implementation issues, such as moving from office-based to field-based survey administration at follow-up, may have contributed to the large declines reported by both groups