2,022 research outputs found
Increased HIV Incidence in Men Who Have Sex with Men Despite High Levels of ART-Induced Viral Suppression: Analysis of an Extensively Documented Epidemic
Background: There is interest in expanding ART to prevent HIV transmission, but in the group with the highest levels of ART use, men-who-have-sex-with-men (MSM), numbers of new infections diagnosed each year have not decreased as ART coverage has increased for reasons which remain unclear.
Methods: We analysed data on the HIV-epidemic in MSM in the UK from a range of sources using an individual-based simulation model. Model runs using parameter sets found to result in good model fit were used to infer changes in HIV-incidence and risk behaviour.
Results: HIV-incidence has increased (estimated mean incidence 0.30/100 person-years 1990–1997, 0.45/100 py 1998–2010), associated with a modest (26%) rise in condomless sex. We also explored counter-factual scenarios: had ART not been introduced, but the rise in condomless sex had still occurred, then incidence 2006–2010 was 68% higher; a policy of ART initiation in all diagnosed with HIV from 2001 resulted in 32% lower incidence; had levels of HIV testing been higher (68% tested/year instead of 25%) incidence was 25% lower; a combination of higher testing and ART at diagnosis resulted in 62% lower incidence; cessation of all condom use in 2000 resulted in a 424% increase in incidence. In 2010, we estimate that undiagnosed men, the majority in primary infection, accounted for 82% of new infections.
Conclusion: A rise in HIV-incidence has occurred in MSM in the UK despite an only modest increase in levels of condomless sex and high coverage of ART. ART has almost certainly exerted a limiting effect on incidence. Much higher rates of HIV testing combined with initiation of ART at diagnosis would be likely to lead to substantial reductions in HIV incidence. Increased condom use should be promoted to avoid the erosion of the benefits of ART and to prevent other serious sexually transmitted infections
Cosmological Results from High-z Supernovae
The High-z Supernova Search Team has discovered and observed 8 new supernovae
in the redshift interval z=0.3-1.2. These independent observations, confirm the
result of Riess et al. (1998a) and Perlmutter et al. (1999) that supernova
luminosity distances imply an accelerating universe. More importantly, they
extend the redshift range of consistently observed SN Ia to z~1, where the
signature of cosmological effects has the opposite sign of some plausible
systematic effects. Consequently, these measurements not only provide another
quantitative confirmation of the importance of dark energy, but also constitute
a powerful qualitative test for the cosmological origin of cosmic acceleration.
We find a rate for SN Ia of 1.4+/-0.5E-04 h^3/Mpc^3/yr at a mean redshift of
0.5. We present distances and host extinctions for 230 SN Ia. These place the
following constraints on cosmological quantities: if the equation of state
parameter of the dark energy is w=-1, then H0 t0 = 0.96+/-0.04, and O_l - 1.4
O_m = 0.35+/-0.14. Including the constraint of a flat Universe, we find O_m =
0.28+/-0.05, independent of any large-scale structure measurements. Adopting a
prior based on the 2dF redshift survey constraint on O_m and assuming a flat
universe, we find that the equation of state parameter of the dark energy lies
in the range -1.48-1,
we obtain w<-0.73 at 95% confidence. These constraints are similar in precision
and in value to recent results reported using the WMAP satellite, also in
combination with the 2dF redshift survey.Comment: 50 pages, AAS LateX, 15 figures, 15 tables. Accepted for publication
by Astrophysical Journa
Imaging and Demography of the Host Galaxies of High-Redshift Type Ia Supernovae
We present the results of a study of the host galaxies of high redshift Type
Ia supernovae (SNe Ia). We provide a catalog of 18 hosts of SNe Ia observed
with the Hubble Space Telescope (HST) by the High-z Supernova Search Team
(HZT), including images, scale-lengths, measurements of integrated (Hubble
equivalent) BVRIZ photometry in bands where the galaxies are brighter than m ~
25 mag, and galactocentric distances of the supernovae. We compare the
residuals of SN Ia distance measurements from cosmological fits to measurable
properties of the supernova host galaxies that might be expected to correlate
with variable properties of the progenitor population, such as host galaxy
color and position of the supernova. We find mostly null results; the current
data are generally consistent with no correlations of the distance residuals
with host galaxy properties in the redshift range 0.42 < z < 1.06. Although a
subsample of SN hosts shows a formally significant (3-sigma) correlation
between apparent V-R host color and distance residuals, the correlation is not
consistent with the null results from other host colors probed by our largest
samples. There is also evidence for the same correlations between SN Ia
properties and host type at low redshift and high redshift. These similarities
support the current practice of extrapolating properties of the nearby
population to high redshifts pending more robust detections of any correlations
between distance residuals from cosmological fits and host properties.Comment: 35 pages, 12 figures, 4 tables, accepted for publication in A
Hubble Space Telescope and Ground-Based Observations of Type Ia Supernovae at Redshift 0.5: Cosmological Implications
We present observations of the Type Ia supernovae (SNe) 1999M, 1999N, 1999Q,
1999S, and 1999U, at redshift z~0.5. They were discovered in early 1999 with
the 4.0~m Blanco telescope at Cerro Tololo Inter-American Observatory by the
High-z Supernova Search Team (HZT) and subsequently followed with many
ground-based telescopes. SNe 1999Q and 1999U were also observed with the Hubble
Space Telescope. We computed luminosity distances to the new SNe using two
methods, and added them to the high-z Hubble diagram that the HZT has been
constructing since 1995.
The new distance moduli confirm the results of previous work. At z~0.5,
luminosity distances are larger than those expected for an empty universe,
implying that a ``Cosmological Constant,'' or another form of ``dark energy,''
has been increasing the expansion rate of the Universe during the last few
billion years.Comment: 68 pages, 22 figures. Scheduled for the 01 February 2006 issue of
Ap.J. (v637
Strokes of serendipity: community co-curation and engagement with digital heritage
This article explores the potential that community–led digital engagement with heritage holds for stimulating active citizenship through taking responsibility for shared cultural heritage and for fostering long-lasting relationships between local community heritage groups and national museums. Through the lens of a pilot project titled Science Museum: Community-in- Residence, we discovered that — despite working with community groups that were already loyal to and enjoyed existing working ties with the Science Museum in London, U.K — this undertaking proved challenging owing to a range of structural and logistical issues even before the application of digital devices and tools had been considered. These challenges notwithstanding, the pilot found that the creation of time and space for face-to-face dialogue and interactions between the Science Museum and the participating community heritage groups helped to establish the parameters within which digital co-curation can effectively occur. This, in turn, informed the development of a digital prototype with huge potential to enable remote, virtual connectivity to, and interactivity with, conversations about shared heritage. The ultimate goal was two-fold: (a) to help facilitate collaborative sense-making of our shared past, and (b) to aid the building of sustainable institutional and community/public working ties around emerging affinities, agendas and research questions in relation to public history and heritage
The Impact of HAART on the Respiratory Complications of HIV Infection: Longitudinal Trends in the MACS and WIHS Cohorts
Objective: To review the incidence of respiratory conditions and their effect on mortality in HIV-infected and uninfected individuals prior to and during the era of highly active antiretroviral therapy (HAART). Design: Two large observational cohorts of HIV-infected and HIV-uninfected men (Multicenter AIDS Cohort Study [MACS]) and women (Women's Interagency HIV Study [WIHS]), followed since 1984 and 1994, respectively. Methods: Adjusted odds or hazards ratios for incident respiratory infections or non-infectious respiratory diagnoses, respectively, in HIV-infected compared to HIV-uninfected individuals in both the pre-HAART (MACS only) and HAART eras; and adjusted Cox proportional hazard ratios for mortality in HIV-infected persons with lung disease during the HAART era. Results: Compared to HIV-uninfected participants, HIV-infected individuals had more incident respiratory infections both pre-HAART (MACS, odds ratio [adjusted-OR], 2.4; 95% confidence interval [CI], 2.2-2.7; p<0.001) and after HAART availability (MACS, adjusted-OR, 1.5; 95%CI 1.3-1.7; p<0.001; WIHS adjusted-OR, 2.2; 95%CI 1.8-2.7; p<0.001). Chronic obstructive pulmonary disease was more common in MACS HIV-infected vs. HIV-uninfected participants pre-HAART (hazard ratio [adjusted-HR] 2.9; 95%CI, 1.02-8.4; p = 0.046). After HAART availability, non-infectious lung diseases were not significantly more common in HIV-infected participants in either MACS or WIHS participants. HIV-infected participants in the HAART era with respiratory infections had an increased risk of death compared to those without infections (MACS adjusted-HR, 1.5; 95%CI, 1.3-1.7; p<0.001; WIHS adjusted-HR, 1.9; 95%CI, 1.5-2.4; p<0.001). Conclusion: HIV infection remained a significant risk for infectious respiratory diseases after the introduction of HAART, and infectious respiratory diseases were associated with an increased risk of mortality. © 2013 Gingo et al
The DEEP2 Galaxy Redshift Survey: First results on galaxy groups
We use the first 25% of the DEEP2 Galaxy Redshift Survey spectroscopic data
to identify groups and clusters of galaxies in redshift space. The data set
contains 8370 galaxies with confirmed redshifts in the range 0.7 <= z <= 1.4,
over one square degree on the sky. Groups are identified using an algorithm
(the Voronoi-Delaunay Method) that has been shown to accurately reproduce the
statistics of groups in simulated DEEP2-like samples. We optimize this
algorithm for the DEEP2 survey by applying it to realistic mock galaxy catalogs
and assessing the results using a stringent set of criteria for measuring
group-finding success, which we develop and describe in detail here. We find in
particular that the group-finder can successfully identify ~78% of real groups
and that ~79% of the galaxies that are true members of groups can be identified
as such. Conversely, we estimate that ~55% of the groups we find can be
definitively identified with real groups and that ~46% of the galaxies we place
into groups are interloper field galaxies. Most importantly, we find that it is
possible to measure the distribution of groups in redshift and velocity
dispersion, n(sigma,z), to an accuracy limited by cosmic variance, for
dispersions greater than 350km/s. We anticipate that such measurements will
allow strong constraints to be placed on the equation of state of the dark
energy in the future. Finally, we present the first DEEP2 group catalog, which
assigns 32% of the galaxies to 899 distinct groups with two or more members,
153 of which have velocity dispersions above 350km/s. We provide locations,
redshifts and properties for this high-dispersion subsample. This catalog
represents the largest sample to date of spectroscopically detected groups at
z~1.Comment: 19 pages, 13 figures, 3 tables. v1: Submitted to ApJ v2: Updated with
minor changes to agree with version to appear in Ap
Sources and Coverage of Medical News on Front Pages of US Newspapers
Background: Medical news that appears on newspaper front pages is intended to reach a wide audience, but how this type of medical news is prepared and distributed has not been systematically researched. We thus quantified the level of visibility achieved by front-page medical stories in the United States and analyzed their news sources. Methodology: Using the online resource Newseum, we investigated front-page newspaper coverage of four prominent medical stories, and a high-profile non-medical news story as a control, reported in the US in 2007. Two characteristics were quantified by two raters: which newspaper titles carried each target front-page story (interrater agreement, >96%; kappa, >0.92) and the news sources of each target story (interrater agreement, >94%; kappa, >0.91). National rankings of the top 200 US newspapers by audited circulation were used to quantify the extent of coverage as the proportion of the total circulation of ranked newspapers in Newseum. Findings: In total, 1630 front pages were searched. Each medical story appeared on the front pages of 85 to 117 (67.5%-78.7%) ranked newspaper titles that had a cumulative daily circulation of 23.1 to 33.4 million, or 61.8% to 88.4% of all newspapers. In contrast, the non-medical story achieved front-page coverage in 152 (99.3%) newspaper titles with a total circulation of 41.0 million, or 99.8% of all newspapers. Front-page medical stories varied in their sources, but the Washington Post, Los Angeles Times, New York Times and the Associated Press together supplied 61.7% of the total coverage of target front-page medical stories. Conclusion: Front-page coverage of medical news from different sources is more accurately revealed by analysis of circulation counts rather than of newspaper titles. Journals wishing to widen knowledge of research news and organizations with important health announcements should target at least the four dominant media organizations identified in this study
Benefits, Barriers and Enablers of Breastfeeding: Factor Analysis of Population Perceptions in Western Australia
Objective: The objective of this study was to investigate knowledge and community perceptions of breastfeeding in Western Australia using a factor analysis approach. Methods: Data were pooled from five Nutrition Monitoring Survey Series which included information on breastfeeding from 4,802 Western Australian adults aged 18–64 years. Tetrachoric factor analysis was conducted for data reduction and significant associations identified using logistic, ordinal and poisson regression analyses. Results: Four factors were derived for benefits (it’s natural, good nutrition, good for the baby, and convenience), barriers (breastfeeding problems, poor community acceptability, having to go back to work, and inconvenience) and for enablers (breastfeeding education, community support, family support and not having to work).As assessed by standardized odds ratios the most important covariates across benefit factors were: importance of breastfeeding (ORs range from 1.22–1.44),female gender (ORs range from 0.80 to 1.46), being able to give a time for how long a baby should be breastfed (ORs range from 0.96 to 1.27) and education (less than high school to university completion) (ORs range from 0.95 to 1.23); the most important covariate across barrier factors was being able to give a time for how long a baby should be breastfed (ORs range from 0.89 to 1.93); and the most important covariates across all enabling factors were education (ORs range from 1.14 to1.32) and being able to give a time for how long a baby should be breastfed (ORs range from 1.17 to 1.42).Conclusions: Being female, rating breastfeeding as important, believing that babies should be breastfed for a period of time and education accounted for most of the statistically significant associations. The differences between male and female perceptions require investigation particularly in relation to returning to work
Optical Spectra of Type Ia Supernovae at z=0.46 and z=1.2
We present optical spectra, obtained with the Keck 10-m telescope, of two
high-redshift type Ia supernovae (SNe Ia) discovered by the High-z Supernova
Search Team: SN 1999ff at z=0.455 and SN 1999fv at z~1.2, the highest-redshift
published SN Ia spectrum. Both SNe were at maximum light when the spectra were
taken. We compare our high-z spectra with low-z normal and peculiar SNe Ia as
well as with SNe Ic, Ib, and II. There are no significant differences between
SN 1999ff and normal SNe Ia at low redshift. SN 1999fv appears to be a SN Ia
and does not resemble the most peculiar nearby SNe Ia.Comment: 6 pages including 2 figures; to appear in The Astrophysical Journal
Letter
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