152 research outputs found
Patterns of Human Herpesvirus-8 Oral Shedding among Diverse Cohorts of Human Herpesvirus-8 Seropositive Persons
Human herpesvirus-8 (HHV-8), the etiologic agent of Kaposi sarcoma (KS), establishes lifelong latent infection with periodic lytic replication (âsheddingâ) at mucosal sites, especially the oropharynx. Patterns of HHV-8 shedding are not well understood, and require elucidation to better predict risk of HHV-8 related malignancies in those infected. We sought to characterize patterns of HHV-8 oropharyngeal shedding among diverse cohorts that enrolled HHV-8 seropositive persons
Dry Mergers in GEMS: The Dynamical Evolution of Massive Early-Type Galaxies
We have used the 28'x 28' HST image mosaic from the GEMS (Galaxy Evolution
from Morphology and SEDs) survey in conjunction with the COMBO-17 photometric
redshift survey to constrain the incidence of major mergers between
spheroid-dominated galaxies with little cold gas (dry mergers) since z = 0.7. A
set of N-body merger simulations was used to explore the morphological
signatures of such interactions: they are recognizable either as < 5kpc
separation close pairs or because of broad, low surface brightness tidal
features and asymmetries. Data with the depth and resolution of GEMS are
sensitive to dry mergers between galaxies with M_V < -20.5 for z < 0.7; dry
mergers at higher redshifts are not easily recovered in single-orbit HST
imaging. Six dry mergers (12 galaxies) with luminosity ratios between 1:1 and
4:1 were found from a sample of 379 red early-type galaxies with M_V < -20.5
and 0.1 < z < 0.7. The simulations suggest that the morphological signatures of
dry merging are visible for ~250Myr and we use this timescale to convert the
observed merger incidence into a rate. On this basis we find that present day
spheroidal galaxies with M_V < -20.5 on average have undergone between 0.5 and
2 major dry mergers since z ~ 0.7. We have compared this result with the
predictions of a Cold Dark Matter based semi-analytic galaxy formation model.
The model reproduces the observed declining major merger fraction of bright
galaxies and the space density of luminous early-type galaxies reasonably well.
The predicted dry merger fraction is consistent with our observational result.
Hence, hierarchical models predict and observations now show that major dry
mergers are an important driver of the evolution of massive early-type galaxies
in recent epochs.Comment: ApJ, in press. The paper has been extensively modified, detailing the
automated+visual selection and dry merger classification. 11 pages emulateapj
with 9 reduced-quality figures. A high quality copy is available at
http://www.mpia-hd.mpg.de/homes/bell/papers/dry.ps.g
Disparities in registration and use of an online patient portal among older adults: findings from the LitCog cohort
(C) The Author 2015. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved.Financial disclosure: This project was supported by the
National Institute on Aging (R01 AG030611), the National
Center for Research Resources (5UL1RR025741), and the
National Center for Advancing Translational Sciences (Grant
8UL1TR000150). The content is solely the responsibility of the
authors and does not necessarily represent the official views of
the National Institutes of Health. Smith is currently supported
by a Cancer Research UK Fellowship
The PTF Orion Project: a Possible Planet Transiting a T-Tauri Star
We report observations of a possible young transiting planet orbiting a
previously known weak-lined T-Tauri star in the 7-10 Myr old Orion-OB1a/25-Ori
region. The candidate was found as part of the Palomar Transient Factory (PTF)
Orion project. It has a photometric transit period of 0.448413 +- 0.000040
days, and appears in both 2009 and 2010 PTF data. Follow-up low-precision
radial velocity (RV) observations and adaptive optics imaging suggest that the
star is not an eclipsing binary, and that it is unlikely that a background
source is blended with the target and mimicking the observed transit. RV
observations with the Hobby-Eberly and Keck telescopes yield an RV that has the
same period as the photometric event, but is offset in phase from the transit
center by approximately -0.22 periods. The amplitude (half range) of the RV
variations is 2.4 km/s and is comparable with the expected RV amplitude that
stellar spots could induce. The RV curve is likely dominated by stellar spot
modulation and provides an upper limit to the projected companion mass of M_p
sin i_orb < 4.8 +- 1.2 M_Jup; when combined with the orbital inclination, i
orb, of the candidate planet from modeling of the transit light curve, we find
an upper limit on the mass of the planetary candidate of M_p < 5.5 +- 1.4
M_Jup. This limit implies that the planet is orbiting close to, if not inside,
its Roche limiting orbital radius, so that it may be undergoing active mass
loss and evaporation.Comment: Corrected typos, minor clarifications; minor updates/corrections to
affiliations and bibliography. 35 pages, 10 figures, 3 tables. Accepted to
Ap
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Statistical Challenges When Analyzing SARS-CoV-2 RNA Measurements Below the Assay Limit of Quantification in COVID-19 Clinical Trials
Most clinical trials evaluating coronavirus disease 2019 (COVID-19) therapeutics include assessments of antiviral activity. In recently completed outpatient trials, changes in nasal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA levels from baseline were commonly assessed using analysis of covariance (ANCOVA) or mixed models for repeated measures (MMRM) with single imputation for results below assay lower limits of quantification (LLoQ). Analyzing changes in viral RNA levels with singly imputed values can lead to biased estimates of treatment effects. In this article, using an illustrative example from the ACTIV-2 trial, we highlight potential pitfalls of imputation when using ANCOVA or MMRM methods, and illustrate how these methods can be used when considering value
Report of the Topical Group on Dark Energy and Cosmic Acceleration: Complementarity of Probes and New Facilities for Snowmass 2021
The mechanism(s) driving the early- and late-time accelerated expansion of
the Universe represent one of the most compelling mysteries in fundamental
physics today. The path to understanding the causes of early- and late-time
acceleration depends on fully leveraging ongoing surveys, developing and
demonstrating new technologies, and constructing and operating new instruments.
This report presents a multi-faceted vision for the cosmic survey program in
the 2030s and beyond that derives from these considerations. Cosmic surveys
address a wide range of fundamental physics questions, and are thus a unique
and powerful component of the HEP experimental portfolio.Comment: Submitted to the Proceedings of the US Community Study on the Future
of Particle Physics (Snowmass 2021); Topical Group Report for CF06 (Cosmic
Frontier Topical Group on Dark Energy and Cosmic Acceleration:
Complementarity of Probes and New Facilitie
TOI-2015b: A Warm Neptune with Transit Timing Variations Orbiting an Active mid M Dwarf
We report the discovery of a close-in () warm Neptune with clear transit timing variations (TTVs)
orbiting the nearby () active M4 star, TOI-2015. We
characterize the planet's properties using TESS photometry, precise
near-infrared radial velocities (RV) with the Habitable-zone Planet Finder (HP)
Spectrograph, ground-based photometry, and high-contrast imaging. A joint
photometry and RV fit yields a radius , mass , and
density for TOI-2015b,
suggesting a likely volatile-rich planet. The young, active host star has a
rotation period of and
associated rotation-based age estimate of . Though
no other transiting planets are seen in the TESS data, the system shows clear
TTVs of super period and
amplitude . After considering multiple likely
period ratio models, we show an outer planet candidate near a 2:1 resonance can
explain the observed TTVs while offering a dynamically stable solution.
However, other possible two-planet solutions -- including 3:2 and 4:3 resonance
-- cannot be conclusively excluded without further observations. Assuming a 2:1
resonance in the joint TTV-RV modeling suggests a mass of
for TOI-2015b and
for the outer candidate.
Additional transit and RV observations will be beneficial to explicitly
identify the resonance and further characterize the properties of the system.Comment: 28 pages, 15 figures, 6 tables. As submitted to AAS Journal
Predictors of SARS-CoV-2 RNA From Nasopharyngeal Swabs and Concordance With Other Compartments in Nonhospitalized Adults With Mild to Moderate COVID-19
Background Identifying characteristics associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA shedding may be useful to understand viral compartmentalization, disease pathogenesis, and risks for viral transmission. Methods Participants were enrolled August 2020 to February 2021 in ACTIV-2/A5401, a placebo-controlled platform trial evaluating investigational therapies for mild-to-moderate coronavirus disease 2019 (COVID-19), and underwent quantitative SARS-CoV-2 RNA testing on nasopharyngeal and anterior nasal swabs, oral wash/saliva, and plasma at entry (day 0, pretreatment) and days 3, 7, 14, and 28. Concordance of RNA levels (copies/mL) across compartments and predictors of nasopharyngeal RNA levels were assessed at entry (n = 537). Predictors of changes over time were evaluated among placebo recipients (n = 265) with censored linear regression models. Results Nasopharyngeal and anterior nasal RNA levels at study entry were highly correlated (r = 0.84); higher levels of both were associated with greater detection of RNA in plasma and oral wash/saliva. Older age, White non-Hispanic race/ethnicity, lower body mass index (BMI), SARS-CoV-2 immunoglobulin G seronegativity, and shorter prior symptom duration were associated with higher nasopharyngeal RNA at entry. In adjusted models, body mass index and race/ethnicity associations were attenuated, but the association with age remained (for every 10 years older, mean nasopharyngeal RNA was 0.27 log10 copies/mL higher; P < .001). Examining longitudinal viral RNA levels among placebo recipients, women had faster declines in nasopharyngeal RNA than men (mean change, â2.0 vs â1.3 log10 copies/mL, entry to day 3; P < .001). Conclusions SARS-CoV-2 RNA shedding was concordant across compartments. Age was strongly associated with viral shedding, and men had slower viral clearance than women, which could explain sex differences in acute COVID-19 outcomes
Feedback in simulations of disc-galaxy major mergers
Using hydrodynamic simulations of disc-galaxy major mergers, we investigate
the star formation history and remnant properties when various parametrizations
of a simple stellar feedback model are implemented. The simulations include
radiative cooling, a density-dependent star formation recipe and a model for
feedback from massive stars. The feedback model stores supernova feedback
energy within individual gas particles and dissipates this energy on a
time-scale specified by two free parameters; tau_fb, which sets the dissipative
time-scale, and n, which sets the effective equation of state in star-forming
regions. Using a self-consistent disc galaxy, modelled after a local Sbc
spiral, in both isolated and major-merger simulations, we investigate
parametrizations of the feedback model that are selected with respect to the
quiescent disc stability. These models produce a range of star formation
histories that are consistent with the star formation relation found by
Kennicutt. All major mergers produce a population of new stars that is highly
centrally concentrated, demonstrating a distinct break in the r1/4 surface
density profile, consistent with previous findings. The half-mass radius and
one-dimensional velocity dispersion are affected by the feedback model used.
Finally, we compare our results to those of previous simulations of star
formation in disc-galaxy major mergers, addressing the effects of star
formation normalization, the version of smoothed particle hydrodynamics (SPH)
employed and assumptions about the interstellar medium.Comment: update to match published versio
Estrogenic botanical supplements, health-related quality of life, fatigue, and hormone-related symptoms in breast cancer survivors: a HEAL study report
<p>Abstract</p> <p>Background</p> <p>It remains unclear whether estrogenic botanical supplement (EBS) use influences breast cancer survivors' health-related outcomes.</p> <p>Methods</p> <p>We examined the associations of EBS use with health-related quality of life (HRQOL), with fatigue, and with 15 hormone-related symptoms such as hot flashes and night sweats among 767 breast cancer survivors participating in the Health, Eating, Activity, and Lifestyle (HEAL) Study. HRQOL was measured by the Medical Outcomes Study short form-36 physical and mental component scale summary score. Fatigue was measured by the Revised-Piper Fatigue Scale score.</p> <p>Results</p> <p>Neither overall EBS use nor the number of EBS types used was associated with HRQOL, fatigue, or hormone-related symptoms. However, comparisons of those using each specific type of EBS with non-EBS users revealed the following associations. Soy supplements users were more likely to have a better physical health summary score (odds ratio [OR] = 1.66, 95% confidence interval [CI] = 1.02-2.70). Flaxseed oil users were more likely to have a better mental health summary score (OR = 1.76, 95% CI = 1.05-2.94). Ginseng users were more likely to report severe fatigue and several hormone-related symptoms (all ORs â„ 1.7 and all 95% CIs exclude 1). Red clover users were less likely to report weight gain, night sweats, and difficulty concentrating (all OR approximately 0.4 and all 95% CIs exclude 1). Alfalfa users were less likely to experience sleep interruption (OR = 0.28, 95% CI = 0.12-0.68). Dehydroepiandrosterone users were less likely to have hot flashes (OR = 0.33, 95% CI = 0.14-0.82).</p> <p>Conclusions</p> <p>Our findings indicate that several specific types of EBS might have important influences on a woman's various aspects of quality of life, but further verification is necessary.</p
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