682 research outputs found
The Chemical Properties of Milky Way and M31 Globular Clusters: I. A Comparative Study
A comparative analysis is performed between high-quality integrated spectra
of 30 globular clusters in M31, 20 Milky Way clusters, and a sample of field
and cluster elliptical galaxies. We find that the Lick CN indices in the M31
and Galactic clusters are enhanced relative to the bulges of the Milky Way,
M31, and elliptical spheroids. Although not seen in the Lick CN indices, the
near-UV cyanogen feature (3883 A) is strongly enhanced in M31 clustesr with
respect to the Galactic globulars at metallicities, --1.5<[Fe/H]<--0.3. Carbon
shows signs of varying amongst these two groups. For [Fe/H]>--0.8, we observe
no siginificant differences in the Hdelta, Hgamma, or Hbeta indices between the
M31 and Galactic globulars. The sample of ellipticals lies offset from the loci
of all the globulars in the Cyanogen--[MgFe], and Balmer--[MgFe] planes. Six of
the M31 cluster spectra appear young, and are projected onto the M31 disk.
Population synthesis models suggest that these are metal-rich clusters with
ages 100--800 Myr, metallicities --0.20 < [Fe/H] <0.35, and masses 0.7
-7.0x10^4 Msun. Two other young clusters are Hubble V in NGC 205, and an older
(~3 Gyr) cluster ~7 kpc away from the plane of the disk. The six clusters
projected onto the disk rotate in a similar fashion to the HI gas in M31, and
three clusters exhibit thin disk kinematics (Morrison et al.). Dynamical masses
and structural parameters are required for these objects to determine whether
they are massive open clusters or globular clusters. If the latter, our
findings suggest globular clusters may trace the build up of galaxy disks. In
either case, we conclude that these clusters are part of a young, metal-rich
disk cluster system in M31, possibly as young as 1 Gyr old.Comment: 52 pages, 14 figures, 8 tables, minor revisions in response to
referee, conclusions remain the same. Scheduled to appear in the October 2004
issue of The Astronomical Journa
Globular clusters in the outer halo of M31: the survey
We report the discovery of 40 new globular clusters (GCs) that have been
found in surveys of the halo of M31 based on INT/WFC and CHFT/Megacam imagery.
A subset of these these new GCs are of an extended, diffuse nature, and include
those already found in Huxor et al. (2005). The search strategy is described
and basic positional and V and I photometric data are presented for each
cluster. For a subset of these clusters, K-band photometry is also given. The
new clusters continue to be found to the limit of the survey area (~100 kpc),
revealing that the GC system of M31 is much more extended than previously
realised. The new clusters increase the total number of confirmed GCs in M31 by
approximately 10% and the number of confirmed GCs beyond 1 degree (~14 kpc) by
more than 75%. We have also used the survey imagery as well recent HST archival
data to update the Revised Bologna Catalogue (RBC) of M31 globular clusters.Comment: Accepted to MNRA
Gestational weight gain in overweight and obese women enrolled in a healthy lifestyle and eating habits program
OBJECTIVES:
To determine whether changes in lifestyle in women with BMI > 25 could decrease gestational weight gain and unfavorable pregnancy outcomes.
METHODS:
Women with BMI > 25 were randomized at 1st trimester to no intervention or a Therapeutic Lifestyle Changes (TLC) Program including diet (overweight: 1700 kcal/day, obese: 1800 kcal/day) and mild physical activity (30 min/day, 3 times/week). At baseline and at the 36th week women filled-in a Food Frequency Questionnaire.
OUTCOMES:
gestational weight gain, gestational diabetes mellitus, gestational hypertension, preterm delivery. Data stratified by BMI categories.
RESULTS:
Socio-demographic features were similar between groups (TLC: 33 cases,
CONTROLS:
28 cases). At term, gestational weight gain in obese women randomized to TLC group was lower (6.7 ± 4.3 kg) versus controls (10.1 ± 5.6 kg, p = 0.047). Gestational diabetes mellitus, gestational hypertension and preterm delivery were also significantly lower. TLC was an independent factor in preventing gestational weight gain, gestational diabetes mellitus, gestational hypertension. Significant changes in eating habits occurred in the TLC group, which increased the number of snacks, the intake of fruits-vegetables and decreased the consumption of sugar.
CONCLUSIONS:
A caloric restriction associated to changes in eating behavior and constant physical activity, is able to reduce gestational weight gain and related pregnancy complications in obese women.Objectives: To determine whether changes in lifestyle in women with BMI > 25 could decrease gestational weight gain and unfavorable pregnancy outcomes. Methods: Women with BMI > 25 were randomized at 1st trimester to no intervention or a Therapeutic Lifestyle Changes (TLC) Program including diet (overweight: 1700 kcal/day, obese: 1800 kcal/day) and mild physical activity (30 min/day, 3 times/week). At baseline and at the 36th week women filled-in a Food Frequency Questionnaire. Outcomes: gestational weight gain, gestational diabetes mellitus, gestational hypertension, preterm delivery. Data stratified by BMI categories. Results: Socio-demographic features were similar between groups (TLC: 33 cases, Controls: 28 cases). At term, gestational weight gain in obese women randomized to TLC group was lower (6.7 ± 4.3 kg) versus controls (10.1 ± 5.6 kg, p = 0.047). Gestational diabetes mellitus, gestational hypertension and preterm delivery were also significantly lower. TLC was an independent factor in preventing gestational weight gain, gestational diabetes mellitus, gestational hypertension. Significant changes in eating habits occurred in the TLC group, which increased the number of snacks, the intake of fruits-vegetables and decreased the consumption of sugar. Conclusions: A caloric restriction associated to changes in eating behavior and constant physical activity, is able to reduce gestational weight gain and related pregnancy complications in obese women. © 2014 Informa UK Ltd
The discovery of 2.78 hour periodic modulation of the X-ray flux from globular cluster source Bo 158 in M31
We report the discovery of periodic intensity dips in the X-ray source XMMU
J004314.1+410724, in the globular cluster Bo158 in M31. The X-ray flux was
modulated by ~83% at a period of 2.78 hr (10017 s) in an XMM-Newton observation
taken 2002 Jan 6-7. The X-ray intensity dips show no energy dependence. We
detected weaker dips with the same period in observations taken 2000 June 25
(XMM-Newton) and 1991 June 26 (ROSAT/PSPC). The amplitude of the modulation has
been found to be anticorrelated with source X-ray flux: it becomes lower when
the source intensity rises. The energy spectrum of Bo158 was stable from
observation to observation, with a characteristic cutoff at ~4-6 keV. The
photo-electric absorption was consistent with the Galactic foreground value. No
significant spectral changes were seen in the course of the dips. If the 2.78
hr cycle is the binary period of Bo158 the system is highly compact, with a
binary separation of ~10e11 cm. The association of the source with a globular
cluster, together with spectral parameters consistent with Galactic neutron
star sources, suggests that X-rays are emitted by an accreting neutron star.
The properties of Bo 158 are somewhat reminiscent of the Galactic X-ray sources
exhibiting a dip-like modulations. We discuss two possible mechanisms
explaining the energy-independent modulation observed in Bo 158: i) the
obscuration of the central source by highly ionized material that scatters
X-rays out of the line of sight; ii) partial covering of an extended source by
an opaque absorber which occults varying fractions of the source.Comment: 10 pages, 4 figures, ApJ, submitted, uses emulateapj styl
On the X-ray source luminosity distributions in the bulge and disk of M31: First results from XMM-Newton survey
We present luminosity distributions for the X-ray sources detected with
XMM-Newton in the bulge and disk of the Andromeda Galaxy (M31). The disk is
clearly lacking the brighter sources which dominate X-ray emission from the
bulge. This is the first convincing evidence for a difference between bulge and
disk X-ray populations in M31. Our results are in good qualitative agreement
with the luminosity distributions for low- and high-mass X-ray binaries
recently obtained by Grimm et al.(2001) for our Galaxy. This confirms that
X-ray population of the disk of M31 is dominated by fainter HMXB sources, while
the bulge is populated with brighter LMXBs.Comment: 5 pages, 2 figures, uses emulateapj.sty, Submitted to ApJ
The Disk and Extraplanar Environment of NGC 247
The stellar content of the spiral galaxy NGC 247 is investigated. The main
sequence turn-off (MSTO) in the inner 12 kpc of the disk corresponds to an age
of 6 Myr. A mean star formation rate (SFR) of 0.1 solar masses per year during
the past 16 Myr is computed from star counts. The color of the red supergiant
plume does not change with radius, suggesting that the mean metallicity of
young stars does not vary by more than 0.1 dex. The number of bright main
sequence stars per local stellar mass density climbs towards larger radii out
to a distance of 12 kpc; the scale lengths that characterize the radial
distributions of young and old stars in the disk thus differ. The density of
bright main sequence stars with respect to projected HI mass gradually drops
with increasing radius. The population of very young stars disappears in the
outer disk; the MSTO at galactocentric radii between 12 and 15 kpc corresponds
to 16 Myr, while between 15 and 18 kpc the age is > 40 Myr. Red giant branch
(RGB) stars are resolved at a projected minor axis galactocentric distance of
12 kpc. There is a broad spread in metallicity among the RGB stars, with a mean
[M/H] = -1.2. The RGB-tip occurs at i' = 24.5 +/- 0.1, indicating that the
distance modulus is 27.9 +/- 0.1. Luminous AGB stars with an age 3 Gyr are also
seen in this field.Comment: Includes 16 eps figures; to appear in the Astrophysical Journa
M31 Globular Cluster X-ray Sources: XMM-Newton and Chandra results
(Abridged) We present the results of M31 globular cluster (GC) X-ray source
survey, based on the data of XMM-Newton and Chandra observations covering ~6100
sq.arcmin of M31. We detected 43 X-ray sources coincident with globular cluster
candidates from optical surveys. The estimated isotropic X-ray luminosities of
GC sources lie between ~10e35 and ~10e39 erg/s in the 0.3 - 10 keV energy band.
The spectral properties and variability of M31 GC X-ray sources are consistent
with that derived for the LMXBs in the bulges of M31 and Milky Way. We found
that ~80% of the M31 GC sources with multiple flux measurements available show
significant variability on a time scales from days to years. The X-ray
luminosity function of GC sources is found to be significantly different from
that of the point sources in the bulge and disk of M31 and that of the Galactic
GC X-ray sources. GC sources make dominant contribution to the bright source
counts in the areas of M31 covered by the survey: ~40% of the total number of
sources with luminosities above 10e37 ergs/s reside in GCs with fraction of GC
sources rising to 67-90% for the luminosities above 10e38 ergs/s. The
contribution of the GC sources to the total number of bright sources found in
M31 is much higher than in the Milky Way galaxy, but surprisingly close to that
of the early-type galaxies. The brightest M31 GC sources tend to reside at
large galactocentric distances outside the central bulge. We found that
globular clusters hosting bright X-ray sources are optically brighter and more
metal rich than the rest of M31 globular clusters. The brightest sources with
luminosities above ~10e38 ergs/s show tendency to reside in more metal poor
clusters.Comment: 17 pages including 7 tables, 17 figures, uses emulateapj style.
Submitted to ApJ, a version with full resolution images is available at
http://hea.iki.rssi.ru/~tsp/papers/m31_gcs_astro_ph.ps.g
Ursodeoxycholic acid for liver disease associated with cystic fibrosis: A double-blind multicenter trial
A Synoptic X-ray Study of M31 with the Chandra-HRC
We have obtained 17 epochs of Chandra High Resolution Camera (HRC) snapshot
images, each covering most of the M31 disk. The data cover a total baseline of
2.5 years and contain a mean effective exposure of 17 ks. We have measured the
mean fluxes and long-term lightcurves for 166 objects detected in these data.
At least 25% of the sources show significant variability. The cumulative
luminosity function (CLF) of the disk sources is well-fit by a power-law with a
slope comparable to those observed in typical elliptical galaxies. The CLF of
the bulge is a broken power law similar to measurements made by previous
surveys. We note several sources in the southwestern disk with L_X > 10^{37}
erg/s . We cross-correlate all of our sources with published optical and radio
catalogs, as well as new optical data, finding counterpart candidates for 55
sources. In addition, 17 sources are likely X-ray transients. We analyze
follow-up HST WFPC2 data of two X-ray transients, finding F336W (U-band
equivalent) counterparts. In both cases, the counterparts are variable. In one
case, the optical counterpart is transient with F336W = 22.3 +/- 0.1 mag. The
X-ray and optical properties of this object are consistent with a ~10 solar
mass black hole X-ray nova with an orbital period of ~20 days. In the other
case, the optical counterpart varies between F336W = 20.82 +/- 0.06 mag and
F336W = 21.11 +/- 0.02 mag. Ground-based and HST observations show this object
is bright (V = 18.8 +/- 0.1) and slightly extended. Finally, the frequency of
bright X-ray transients in the M31 bulge suggests that the ratio of neutron
star to black hole primaries in low-mass X-ray binaries (NS/BH) is ~1.Comment: 68 pages (27 text), 8 tables, 16 figures, 1 appendix, accepted by
ApJ; accepted version contains reorganized text, new tables and figures, and
updated result
A two-stage genome-wide association study of sporadic amyotrophic lateral sclerosis
The cause of sporadic amyotrophic lateral sclerosis (ALS) is largely unknown, but genetic factors are thought to play a significant role in determining susceptibility to motor neuron degeneration. To identify genetic variants altering risk of ALS, we undertook a two-stage genome-wide association study (GWAS): we followed our initial GWAS of 545 066 SNPs in 553 individuals with ALS and 2338 controls by testing the 7600 most associated SNPs from the first stage in three independent cohorts consisting of 2160 cases and 3008 controls. None of the SNPs selected for replication exceeded the Bonferroni threshold for significance. The two most significantly associated SNPs, rs2708909 and rs2708851 [odds ratio (OR) = 1.17 and 1.18, and P-values = 6.98 x 10–7 and 1.16 x 10–6], were located on chromosome 7p13.3 within a 175 kb linkage disequilibrium block containing the SUNC1, HUS1 and C7orf57 genes. These associations did not achieve genome-wide significance in the original cohort and failed to replicate in an additional independent cohort of 989 US cases and 327 controls (OR = 1.18 and 1.19, P-values = 0.08 and 0.06, respectively). Thus, we chose to cautiously interpret our data as hypothesis-generating requiring additional confirmation, especially as all previously reported loci for ALS have failed to replicate successfully. Indeed, the three loci (FGGY, ITPR2 and DPP6) identified in previous GWAS of sporadic ALS were not significantly associated with disease in our study. Our findings suggest that ALS is more genetically and clinically heterogeneous than previously recognized. Genotype data from our study have been made available online to facilitate such future endeavors
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