5,704 research outputs found
Near-Infrared Adaptive Optics Imaging of the Central Regions of Nearby Sc Galaxies. II. NGC 247 and NGC 2403
J, H, and K' images obtained with the Canada-France-Hawaii Telescope adaptive
optics system are used to investigate the star-forming histories of the central
regions of the Sc galaxies NGC 247 and NGC 2403. The brightest resolved red
stars within 15 arcsec of the nucleus of each galaxy are red supergiants,
indicating that the central few hundred parsecs of these galaxies experienced
star formation within the last ~ 0.1 Gyr. However, when averaged over Gyr time
scales, the star-forming histories of the inner disks of these galaxies have
been remarkably similar, as expected if the long-term evolution of disks is
defined by local characteristics such as mass density. It is demonstrated that
NGC 247 and NGC 2403, like M33, harbour nuclear star clusters with stellar
contents that differ from the surrounding central light concentrations. The
nucleus of NGC 2403 is significantly bluer than that of the other two galaxies
and the K-band surface brightnesses near the centers of NGC 247 and NGC 2403
are 1 -- 2 mag per square arcsec lower than in M33. Finally, it is noted that
young or intermediate-age nuclear star clusters are a common occurence in
nearby spirals, indicating that nuclear star formation in these objects is
either continuous or episodic on time scales of 0.1 - 1 Gyr.Comment: 27 pages of text and 14 figures; to appear in the Astronomical
Journa
Deep learning for inferring cause of data anomalies
Daily operation of a large-scale experiment is a resource consuming task,
particularly from perspectives of routine data quality monitoring. Typically,
data comes from different sub-detectors and the global quality of data depends
on the combinatorial performance of each of them. In this paper, the problem of
identifying channels in which anomalies occurred is considered. We introduce a
generic deep learning model and prove that, under reasonable assumptions, the
model learns to identify 'channels' which are affected by an anomaly. Such
model could be used for data quality manager cross-check and assistance and
identifying good channels in anomalous data samples. The main novelty of the
method is that the model does not require ground truth labels for each channel,
only global flag is used. This effectively distinguishes the model from
classical classification methods. Being applied to CMS data collected in the
year 2010, this approach proves its ability to decompose anomaly by separate
channels.Comment: Presented at ACAT 2017 conference, Seattle, US
Neutral Hydrogen and Star Formation in the Irregular Galaxy NGC 2366
We present UBVJHKHalpha and HI data of the irregular galaxy NGC 2366. It is a
normal boxy-shaped disk seen at high inclination angle. We do not see any
unambiguous observational signature of a bar. There is an asymmetrical
extension of stars along one end of the major axis of the galaxy, and this is
where the furthest star-forming regions are found, at 1.3R_Holmberg. The HI is
normal in many respects but shows some anomalies: 1) The integrated HI shows
two ridges running parallel to the major axis that deproject to a large ring.
2) The velocity field exhibits several large-scale anomalies superposed on a
rotating disk. 3) The inclination and position angles derived from the
kinematics differ from those dervied from the optical and HI mor- phology. 4)
There are regions in the HI of unusually high velocity dispersion that
correlate with deficits of HI emission in a manner suggestive of long-range,
turbulent pressure equilibrium. Star-forming regions are found where the gas
densities locally exceed 6 Msolar/pc^2. NGC 2366, like other irregulars, has
low gas densities relative to the critical gas densities of gravitational
instability models. Because of the lack of shear in the optical galaxy, there
is little competition to the slow gravitational contraction that follows energy
dissipation. However, the peak gas densities in the star-forming regions are
equal to the local tidal densities for gravitational self-binding of a rotating
cloud. Evidently the large scale gas concentrations are marginally bound
against background galactic tidal forces. This condition for self-binding may
be more fundamental than the instability condition because it is local,
three-dimensional, and does not involve spiral arm generation as an
intermediate step toward star formation.Comment: To be published in ApJ; better figures available ftp.lowell.edu, cd
pub/dah/n2366pape
Beta-Blocker Use in Pregnancy and Risk of Specific Congenital Anomalies: A European Case-Malformed Control Study.
The prevalence of chronic hypertension is increasing in pregnant women. Beta-blockers are among the most prevalent anti-hypertensive agents used in early pregnancy.
The objective of this study was to investigate whether first-trimester use of beta-blockers increases the risk of specific congenital anomalies in offspring.
A population-based case-malformed control study was conducted in 117,122 registrations of congenital anomalies from 17 European Concerted Action on Congenital Anomalies and Twins (EUROCAT) registries participating in EUROmediCAT with data for all or part of the period between 1995 and 2013. Associations previously reported in the literature (signals) were tested and an exploratory analysis was performed to identify new signals. Odds ratios of exposure to any beta-blocker or to a beta-blocker subgroup were calculated for each signal anomaly compared with two control groups (non-chromosomal, non-signal anomalies and chromosomal anomalies). The exploratory analyses were performed for each non-signal anomaly compared with all the other non-signal anomalies.
The signals from the literature (congenital heart defects, oral clefts, neural tube defects and hypospadias) were not confirmed. Our exploratory analysis revealed that multi-cystic renal dysplasia had significantly increased odds of occurring after maternal exposure to combined alpha- and beta-blockers (adjusted odds ratio 3.8; 95% confidence interval 1.3-11.0).
Beta-blocker use in the first trimester of pregnancy was not found to be associated with a higher risk of specific congenital anomalies in the offspring, but a new signal between alpha- and beta-blockers and multi-cystic renal dysplasia was found. Future large epidemiological studies are needed to confirm or refute our findings
Measurement of the Branching Fraction for B- --> D0 K*-
We present a measurement of the branching fraction for the decay B- --> D0
K*- using a sample of approximately 86 million BBbar pairs collected by the
BaBar detector from e+e- collisions near the Y(4S) resonance. The D0 is
detected through its decays to K- pi+, K- pi+ pi0 and K- pi+ pi- pi+, and the
K*- through its decay to K0S pi-. We measure the branching fraction to be
B.F.(B- --> D0 K*-)= (6.3 +/- 0.7(stat.) +/- 0.5(syst.)) x 10^{-4}.Comment: 7 pages, 1 postscript figure, submitted to Phys. Rev. D (Rapid
Communications
Measurement of the quasi-elastic axial vector mass in neutrino-oxygen interactions
The weak nucleon axial-vector form factor for quasi-elastic interactions is
determined using neutrino interaction data from the K2K Scintillating Fiber
detector in the neutrino beam at KEK. More than 12,000 events are analyzed, of
which half are charged-current quasi-elastic interactions nu-mu n to mu- p
occurring primarily in oxygen nuclei. We use a relativistic Fermi gas model for
oxygen and assume the form factor is approximately a dipole with one parameter,
the axial vector mass M_A, and fit to the shape of the distribution of the
square of the momentum transfer from the nucleon to the nucleus. Our best fit
result for M_A = 1.20 \pm 0.12 GeV. Furthermore, this analysis includes updated
vector form factors from recent electron scattering experiments and a
discussion of the effects of the nucleon momentum on the shape of the fitted
distributions.Comment: 14 pages, 10 figures, 6 table
Measurement of the B+ --> p pbar K+ Branching Fraction and Study of the Decay Dynamics
With a sample of 232x10^6 Upsilon(4S) --> BBbar events collected with the
BaBar detector, we study the decay B+ --> p pbar K+ excluding charmonium decays
to ppbar. We measure a branching fraction Br(B+ --> p pbar
K+)=(6.7+/-0.5+/-0.4)x10^{-6}. An enhancement at low ppbar mass is observed and
the Dalitz plot asymmetry suggests dominance of the penguin amplitude in this B
decay. We search for a pentaquark candidate Theta*++ decaying into pK+ in the
mass range 1.43 to 2.00 GeV/c2 and set limits on Br(B+ -->
Theta*++pbar)xBr(Theta*++ --> pK+) at the 10^{-7} level.Comment: 8 pages, 7 postscript figures, submitted to Phys. Rev. D (Rapid
Communications
Study of e+e- --> pi+ pi- pi0 process using initial state radiation with BABAR
The process e+e- --> pi+ pi- pi0 gamma has been studied at a center-of-mass
energy near the Y(4S) resonance using a 89.3 fb-1 data sample collected with
the BaBar detector at the PEP-II collider. From the measured 3pi mass spectrum
we have obtained the products of branching fractions for the omega and phi
mesons, B(omega --> e+e-)B(omega --> 3pi)=(6.70 +/- 0.06 +/- 0.27)10-5 and
B(phi --> e+e-)B(phi --> 3pi)=(4.30 +/- 0.08 +/- 0.21)10-5, and evaluated the
e+e- --> pi+ pi- pi0 cross section for the e+e- center-of-mass energy range
1.05 to 3.00 GeV. About 900 e+e- --> J/psi gamma --> pi+ pi- pi0 gamma events
have been selected and the branching fraction B(J/psi --> pi+ pi- pi0)=(2.18
+/- 0.19)% has been measured.Comment: 21 pages, 37 postscript figues, submitted to Phys. Rev.
Measurement of Branching Fraction and Dalitz Distribution for B0->D(*)+/- K0 pi-/+ Decays
We present measurements of the branching fractions for the three-body decays
B0 -> D(*)-/+ K0 pi^+/-B0 -> D(*)-/+ K*+/- using
a sample of approximately 88 million BBbar pairs collected by the BABAR
detector at the PEP-II asymmetric energy storage ring.
We measure:
B(B0->D-/+ K0 pi+/-)=(4.9 +/- 0.7(stat) +/- 0.5 (syst)) 10^{-4}
B(B0->D*-/+ K0 pi+/-)=(3.0 +/- 0.7(stat) +/- 0.3 (syst)) 10^{-4}
B(B0->D-/+ K*+/-)=(4.6 +/- 0.6(stat) +/- 0.5 (syst)) 10^{-4}
B(B0->D*-/+ K*+/-)=(3.2 +/- 0.6(stat) +/- 0.3 (syst)) 10^{-4}
From these measurements we determine the fractions of resonant events to be :
f(B0-> D-/+ K*+/-) = 0.63 +/- 0.08(stat) +/- 0.04(syst) f(B0-> D*-/+ K*+/-) =
0.72 +/- 0.14(stat) +/- 0.05(syst)Comment: 7 pages, 3 figures submitted to Phys. Rev. Let
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