1,231 research outputs found
Chandra X-ray Observations of 12 Millisecond Pulsars in the Globular Cluster M28
We present a Chandra X-ray Observatory investigation of the millisecond
pulsars (MSPs) in the globular cluster M28 (NGC 6626). In what is one of the
deepest X-ray observations of a globular cluster, we firmly detect seven and
possibly detect two of the twelve known M28 pulsars. With the exception of PSRs
B1821-24 and J1824-2452H, the detected pulsars have relatively soft spectra,
with X-ray luminosities 10^30-31 ergs s^-1 (0.3-8 keV),similar to most
"recycled" pulsars in 47 Tucanae and the field of the Galaxy, implying thermal
emission from the pulsar magnetic polar caps. We present the most detailed
X-ray spectrum to date of the energetic PSR B1821-24. It is well described by a
purely non-thermal spectrum with spectral photon index 1.23 and luminosity
1.4x10^33Theta(D/5.5 kpc)^2 ergs s^-1 (0.3-8 keV), where Theta is the fraction
of the sky covered by the X-ray emission beam(s). We find no evidence for the
previously reported line emission feature around 3.3 keV, most likely as a
consequence of improvements in instrument calibration. The X-ray spectrum and
pulse profile of PSR B1821--24 suggest that the bulk of unpulsed emission from
this pulsar is not of thermal origin, and is likely due to low-level
non-thermal magnetospheric radiation, an unresolved pulsar wind nebula, and/or
small-angle scattering of the pulsed X-rays by interstellar dust grains. The
peculiar binary PSR J1824-2452H shows a relatively hard X-ray spectrum and
possible variability at the binary period, indicative of an intrabinary shock
formed by interaction between the relativistic pulsar wind and matter from its
non-degenerate companion star.Comment: 9 pages, 6 figures. Accepted for publication in the Astophysical
Journa
How do disadvantaged groups perceive allies? Womenâs perceptions of men who confront sexism in an egalitarian or paternalistic way
In this research, we focused on women's perception of men as allies depending on the type of confrontation. We conducted four experimental scenario studies (Study 1 and 2 in a bar setting; Study 3 and 4 in a workplace setting) where a man confronted a sexist comment using either an egalitarian or paternalistic argument. Results showed that women are more likely to perceive egalitarian (vs. paternalistic) confronters as allies (Studies 1â4). This is explained by the fact that they contribute to reducing power asymmetries (decreasing perceived interpersonal power differences: Studies 2 and 4; or increasing women's empowerment: Studies 3 and 4). Furthermore, the egalitarian (vs. paternalistic) confrontation positively impacts interpersonal and intergroup relations, and this is explained by the perception of the confronter as an ally (Studies 1, 2 and 4). We discuss the role of disadvantaged group membersâ perception of advantaged group members to disentangle the complexity of alliances.Spanish Ministry of Science and Innovation,
Grant/Award Numbers: FPU14/0511,
PID2019-111549GB-I00,
MCIN/AEI/10.13039/501100011033Universidad de Granada/CBU
The FIRST Bright Quasar Survey. II. 60 Nights and 1200 Spectra Later
We have used the VLA FIRST survey and the APM catalog of the POSS-I plates as
the basis for constructing a new radio-selected sample of optically bright
quasars. This is the first radio-selected sample that is competitive in size
with current optically selected quasar surveys. Using only two basic criteria,
radio-optical positional coincidence and optical morphology, quasars and BL
Lacs can be identified with 60% selection efficiency; the efficiency increases
to 70% for objects fainter than magnitude 17. We show that a more sophisticated
selection scheme can predict with better than 85% reliability which candidates
will turn out to be quasars.
This paper presents the second installment of the FIRST Bright Quasar Survey
with a catalog of 636 quasars distributed over 2682 square degrees. The quasar
sample is characterized and all spectra are displayed. The FBQS detects both
radio-loud and radio-quiet quasars out to a redshift z>3. We find a large
population of objects of intermediate radio-loudness; there is no evidence in
our sample for a bimodal distribution of radio characteristics. The sample
includes ~29 broad absorption line quasars, both high and low ionization, and a
number of new objects with remarkable optical spectra.Comment: 41 pages plus 39 gifs which contain all quasar spectra. Accepted for
publication in the Astrophysical Journal Supplement Serie
Chandra X-Ray Observatory Observations of the Globular Cluster M71
We observed the nearby, low-density globular cluster M71 (NGC 6838) with the
Chandra X-ray Observatory to study its faint X-ray populations. Five X-ray
sources were found inside the cluster core radius, including the known
eclipsing binary millisecond pulsar (MSP) PSR J1953+1846A. The X-ray light
curve of the source coincident with this MSP shows marginal evidence for
periodicity at the binary period of 4.2 h. Its hard X-ray spectrum and
luminosity resemble those of other eclipsing binary MSPs in 47 Tuc, suggesting
a similar shock origin of the X-ray emission. A further 24 X-ray sources were
found within the half-mass radius, reaching to a limiting luminosity of 1.5
10^30 erg/s (0.3-8 keV). From a radial distribution analysis, we find that
18+/-6 of these 29 sources are associated with M71, somewhat more than
predicted, and that 11+/-6 are background sources, both galactic and
extragalactic. M71 appears to have more X-ray sources between L_X=10^30--10^31
erg/s than expected by extrapolating from other studied clusters using either
mass or collision frequency. We explore the spectra and variability of these
sources, and describe the results of ground-based optical counterpart searches.Comment: 36 pages including 7 figures and 8 tables, accepted by The
Astrophysical Journa
A functional polymorphism in the 5HTR2C gene associated with stress responses also predicts incident cardiovascular events.
Previously we have shown that a functional nonsynonymous single nucleotide polymorphism (rs6318) of the 5HTR2C gene located on the X-chromosome is associated with hypothalamic-pituitary-adrenal axis response to a stress recall task, and with endophenotypes associated with cardiovascular disease (CVD). These findings suggest that individuals carrying the rs6318 Ser23 C allele will be at higher risk for CVD compared to Cys23 G allele carriers. The present study examined allelic variation in rs6318 as a predictor of coronary artery disease (CAD) severity and a composite endpoint of all-cause mortality or myocardial infarction (MI) among Caucasian participants consecutively recruited through the cardiac catheterization laboratory at Duke University Hospital (Durham, NC) as part of the CATHGEN biorepository. Study population consisted of 6,126 Caucasian participants (4,036 [65.9%] males and 2,090 [34.1%] females). A total of 1,769 events occurred (1,544 deaths and 225 MIs; median follow-up time = 5.3 years, interquartile range = 3.3-8.2). Unadjusted Cox time-to-event regression models showed, compared to Cys23 G carriers, males hemizygous for Ser23 C and females homozygous for Ser23C were at increased risk for the composite endpoint of all-cause death or MI: Hazard Ratio (HR) = 1.47, 95% confidence interval (CI) = 1.17, 1.84, p = .0008. Adjusting for age, rs6318 genotype was not related to body mass index, diabetes, hypertension, dyslipidemia, smoking history, number of diseased coronary arteries, or left ventricular ejection fraction in either males or females. After adjustment for these covariates the estimate for the two Ser23 C groups was modestly attenuated, but remained statistically significant: HR = 1.38, 95% CI = 1.10, 1.73, p = .005. These findings suggest that this functional polymorphism of the 5HTR2C gene is associated with increased risk for CVD mortality and morbidity, but this association is apparently not explained by the association of rs6318 with traditional risk factors or conventional markers of atherosclerotic disease
A Chandra X-ray Observatory Study of PSR J1740--5340 and Candidate Millisecond Pulsars in the Globular Cluster NGC 6397
We present a deep Chandra X-ray Observatory study of the peculiar binary
radio millisecond pulsar PSR J1740--5340 and candidate millisecond pulsars
(MSPs) in the globular cluster NGC 6397. The X-rays from PSR J1740--5340 appear
to be non-thermal and exhibit variability at the binary period. These
properties suggest the presence of a relativistic intrabinary shock formed due
to interaction of a relativistic rotation-powered pulsar wind and outflow from
the unusual "red-straggler/sub-subgiant" companion. We find the X-ray source
U18 to show similar X-ray and optical properties to those of PSR J1740--5340,
making it a strong MSP candidate. It exhibits variability on timescales from
hours to years, also consistent with an intrabinary shock origin of its X-ray
emission. The unprecedented depth of the X-ray data allows us to conduct a
complete census of MSPs in NGC 6397. Based on the properties of the present
sample of X-ray--detected MSPs in the Galaxy we find that NGC 6397 probably
hosts no more than 6 MSPs.Comment: 10 pages, 6 figures, 3 tables; accepted for publication in The
Astrophysical Journa
Acculturation, Dietary Behaviors, and Macronutrient intake among Mexican americans With Prediabetes: the Starr County Diabetes Prevention initiative
PURPOSE: The purpose of the study was to examine the influences of sex and acculturation on dietary behaviors, macronutrient intake, and dietary quality in participants enrolled in a diabetes prevention initiative in Starr County, Texas.
METHODS: Baseline data from the Starr County diabetes prevention study (Nâ=â300) were analyzed-acculturation (country of origin, years in Starr County, language and food preferences), depressive symptoms (Patient Health Questionnaire-9), healthy eating self-efficacy (Weight Efficacy Lifestyle Questionnaire-Short Form), diet quality (USDA Healthy Eating Index), fat avoidance (Fat Avoidance Scale, Spanish version), and macronutrients. Descriptive statistics and univariate analysis of covariance were used to examine differences based on acculturation, controlling for sex.
RESULTS: Participants were predominantly female (73%) and, on average, 51âyears of age. Language and food preferences favored Spanish language and Hispanic foods, respectively. The majority (71%) was born in Mexico but had resided in Starr County for 33âyears, on average. Depressive symptoms were moderate, and eating self-efficacy scores suggested low confidence in making healthy food choices, particularly for saturated fats. Spanish language preference was associated with worse dietary habits. The mean dietary quality score was lower than the national average (54 vs 59 nationally); females had slightly higher dietary quality than males and a higher mean fat avoidance score, although differences were not clinically significant. Intakes of carbohydrate, saturated fats, and cholesterol were higher than recommended daily allowances.
CONCLUSIONS: The overall preference for speaking Spanish and the influence of language on dietary intake should inform future dietary interventions. Accommodating cultural norms and food preferences remain major challenges to improving dietary quality among the diverse Hispanic ethnic groups
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