3,944 research outputs found
Effects of delayed cord clamping on residual placental blood volume, hemoglobin and bilirubin levels in term infants: a randomized controlled trial
Objective: The objective of the study was to measure the effects of a 5-min delay (DCC) versus immediate cord clamping (ICC) on residual placental blood volume (RPBV) at birth, and hemoglobin and serum bilirubin at 24 to 48 h of age.
Study Design: In this prospective randomized controlled trial, 73 women with term (37 to 41 weeks) singleton fetuses were randomized to DCC (5 min; n=37) or ICC (\u3c20 s; n=36).
Results: Maternal and infant demographics were not different between the groups. Mean cord clamping time was 303±121 (DCC) versus 23±59 (ICC) s (P\u3c0.001) with 10 protocol violations. Cord milking was the proxy for DCC (n=11) when the provider could not wait. Infants randomized to DCC compared with ICC had significantly less RPBV (20.0 versus 30.8 ml kg−1, P\u3c0.001), higher hemoglobin levels (19.4 versus 17.8 g dl−1, P=0.002) at 24 to 48 h, with no difference in bilirubin levels.
Conclusion: Term infants had early hematological advantage of DCC without increases in hyperbilirubinemia or symptomatic polycythemia
Do the Barker Codes End?
A Barker code is a binary code with k^th autocorrelation <= 1 for all nonzero k.
At the workshop, the Barker code group split into four non-disjoint subgroups:
- An "algebra group", who explored symmetries of the search space that preserve the autocorrelations' magnitude.
- A "computing group", who explored methods for quickly finding binary codes with very good autocorrelation properties.
- A "statistics group", who explored ways to quantify what has been empirically observed about autocorrelation in the search space S_2^N.
- A "continuous group", who explored a non-discrete analogue of the problem of finding sequences with good autocorrelations
Methods to homogenize electrochemical concentration cell (ECC) ozonesonde measurements across changes in sensing solution concentration or ozonesonde manufacturer
Ozone plays a significant role in the chemical and radiative
state of the atmosphere. For this reason there are many instruments used to
measure ozone from the ground, from space, and from balloons. Balloon-borne
electrochemical cell ozonesondes provide some of the best measurements of the
ozone profile up to the mid-stratosphere, providing high vertical resolution,
high precision, and a wide geographic distribution. From the mid-1990s to the
late 2000s the consistency of long-term records from balloon-borne
ozonesondes has been compromised by differences in manufacturers, Science
Pump (SP) and ENSCI (EN), and differences in recommended sensor solution
concentrations, 1.0 % potassium iodide (KI) and the one-half dilution:
0.5 %. To investigate these differences, a number of organizations
have independently undertaken comparisons of the various ozonesonde types and
solution concentrations, resulting in 197 ozonesonde comparison profiles. The
goal of this study is to derive transfer functions to allow measurements
outside of standard recommendations, for sensor composition and ozonesonde
type, to be converted to a standard measurement and thus homogenize the data
to the expected accuracy of 5 % (10 %) in the stratosphere (troposphere).
Subsets of these data have been analyzed previously and intermediate transfer
functions derived. Here all the comparison data are analyzed to compare (1) differences in sensor solution composition for a single ozonesonde type,
(2) differences in ozonesonde type for a single sensor solution composition, and
(3) the World Meteorological Organization's (WMO) and manufacturers'
recommendations of 1.0 % KI solution for Science Pump and 0.5 % KI for
ENSCI. From the recommendations it is clear that ENSCI ozonesondes and
1.0 % KI solution result in higher amounts of ozone sensed. The results
indicate that differences in solution composition and in ozonesonde type
display little pressure dependence at pressures ≥ 30 hPa, and thus the
transfer function can be characterized as a simple ratio of the less
sensitive to the more sensitive method. This ratio is 0.96 for both solution
concentration and ozonesonde type. The ratios differ at pressures < 30 hPa such that OZ0. 5%/OZ1. 0 % = 0. 90 + 0. 041 ⋅ log10(p) and OZSciencePump/OZENSCI = 0. 764 + 0. 133 ⋅ log10(p) for p in units of hPa. For the manufacturer-recommended
solution concentrations the dispersion of the ratio (SP-1.0 / EN-0.5 %), while
significant, is generally within 3 % and centered near 1.0, such that no
changes are recommended. For stations which have used multiple ozonesonde
types with solution concentrations different from the WMO's and
manufacturer's recommendations, this work suggests that a reasonably
homogeneous data set can be created if the quantitative relationships
specified above are applied to the non-standard measurements. This result is
illustrated here in an application to the Nairobi data set
The Bubbling Galactic Disk
A visual examination of the images from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) has revealed 322 partial and closed rings that we propose represent partially or fully enclosed three-dimensional bubbles. We argue that the bubbles are primarily formed by hot young stars in massive star formation regions. We have found an average of about 1.5 bubbles per square degree. About 25% of the bubbles coincide with known radio H II regions, and about 13% enclose known star clusters. It appears that B4-B9 stars (too cool to produce detectable radio H II regions) probably produce about three-quarters of the bubbles in our sample, and the remainder are produced by young O-B3 stars that produce detectable radio H II regions. Some of the bubbles may be the outer edges of H II regions where PAH spectral features are excited and may not be dynamically formed by stellar winds. Only three of the bubbles are identified as known SNRs. No bubbles coincide with known planetary nebulae or W-R stars in the GLIMPSE survey area. The bubbles are small. The distribution of angular diameters peaks between 1' and 3' with over 98% having angular diameters less than 10' and 88% less than 4'. Almost 90% have shell thicknesses between 0.2 and 0.4 of their outer radii. Bubble shell thickness increases approximately linearly with shell radius. The eccentricities are rather large, peaking between 0.6 and 0.7; about 65% have eccentricities between 0.55 and 0.85
Networks of gravitational wave detectors and three figures of merit
This paper develops a general framework for studying the effectiveness of
networks of interferometric gravitational wave detectors and then uses it to
show that enlarging the existing LIGO-VIRGO network with one or more planned or
proposed detectors in Japan (LCGT), Australia, and India brings major benefits,
including much larger detection rate increases than previously thought... I
show that there is a universal probability distribution function (pdf) for
detected SNR values, which implies that the most likely SNR value of the first
detected event will be 1.26 times the search threshold. For binary systems, I
also derive the universal pdf for detected values of the orbital inclination,
taking into account the Malmquist bias; this implies that the number of
gamma-ray bursts associated with detected binary coalescences should be 3.4
times larger than expected from just the beaming fraction of the gamma burst.
Using network antenna patterns, I propose three figures of merit that
characterize the relative performance of different networks... Adding {\em any}
new site to the planned LIGO-VIRGO network can dramatically increase, by
factors of 2 to 4, the detected event rate by allowing coherent data analysis
to reduce the spurious instrumental coincident background. Moving one of the
LIGO detectors to Australia additionally improves direction-finding by a factor
of 4 or more. Adding LCGT to the original LIGO-VIRGO network not only improves
direction-finding but will further increase the detection rate over the
extra-site gain by factors of almost 2, partly by improving the network duty
cycle... Enlarged advanced networks could look forward to detecting three to
four hundred neutron star binary coalescences per year.Comment: 38 pages, 7 figures, 2 tables. Accepted for publication in Classical
and Quantum Gravit
A burst search for gravitational waves from binary black holes
Compact binary coalescence (CBC) is one of the most promising sources of
gravitational waves. These sources are usually searched for with matched
filters which require accurate calculation of the GW waveforms and generation
of large template banks. We present a complementary search technique based on
algorithms used in un-modeled searches. Initially designed for detection of
un-modeled bursts, which can span a very large set of waveform morphologies,
the search algorithm presented here is constrained for targeted detection of
the smaller subset of CBC signals. The constraint is based on the assumption of
elliptical polarisation for signals received at the detector. We expect that
the algorithm is sensitive to CBC signals in a wide range of masses, mass
ratios, and spin parameters. In preparation for the analysis of data from the
fifth LIGO-Virgo science run (S5), we performed preliminary studies of the
algorithm on test data. We present the sensitivity of the search to different
types of simulated CBC waveforms. Also, we discuss how to extend the results of
the test run into a search over all of the current LIGO-Virgo data set.Comment: 12 pages, 4 figures, 2 tables, submitted for publication in CQG in
the special issue for the conference proceedings of GWDAW13; corrected some
typos, addressed some minor reviewer comments one section restructured and
references updated and correcte
The Frequency of Mid-Infrared Excess Sources in Galactic Surveys
We have identified 230 Tycho-2 Spectral Catalog stars that exhibit 8 micron
mid-infrared extraphotospheric excesses in the MidCourse Space Experiment (MSX)
and Spitzer Space Telescope Galactic Legacy MidPlane Survey Extraordinaire
(GLIMPSE) surveys. Of these, 183 are either OB stars earlier than B8 in which
the excess plausibly arises from a thermal bremsstrahlung component or evolved
stars in which the excess may be explained by an atmospheric dust component.
The remaining 47 stars have spectral classifications B8 or later and appear to
be main sequence or late pre-main-sequence objects harboring circumstellar
disks. Six of the 47 stars exhibit multiple signatures characteristic of
pre-main-sequence circumstellar disks, including emission lines, near-infrared
K-band excesses, and X-ray emission. Approximately one-third of the remaining
41 sources have emission lines suggesting relative youth. Of the 25 GLIMPSE
stars with SST data at >24 microns, 20 also show an excess at 24 microns. Three
additional objects have 24 micron upper limits consistent with possible
excesses, and two objects have photospheric measurements at 24 microns. Six MSX
sources had a measurement at wavelengths >8 microns. We modeled the excesses in
26 stars having two or more measurements in excess of the expected photospheres
as single-component blackbodies. We determine probable disk temperatures and
fractional infrared luminosities in the range 191 < T < 787 and 3.9x10^-4 <
L_IR/L_* < 2.7x10^-1. We estimate a lower limit on the fraction of Tycho-2
Spectral Catalog main-sequence stars having mid-IR, but not near-IR, excesses
to be 1.0+-0.3%.Comment: Accepted to Ap
Effects of Placental Transfusion on Neonatal and 18 Month Outcomes in Preterm Infants: A Randomized Controlled Trial
Objective: To assess the effect of delayed cord clamping (DCC) vs immediate cord clamping (ICC) on intraventricular hemorrhage (IVH), late onset sepsis (LOS), and 18-month motor outcomes in preterm infants.
Study Design: Women (n = 208) in labor with singleton fetuses (\u3c32 weeks gestation) were randomized to either DCC (30-45 seconds) or ICC (\u3c10 seconds). The primary outcomes were IVH, LOS, and motor outcomes at 18-22 months corrected age. Intention-to-treat was used for primary analyses.
Results: Cord clamping time was 32 ± 16 (DCC) vs 6.6 ± 6 (ICC) seconds. Infants in the DCC and ICC groups weighed 1203 ± 352 and 1136 ± 350 g and mean gestational age was 28.3 ± 2 and 28.4 ± 2 weeks, respectively. There were no differences in rates of IVH or LOS between groups. At 18-22 months, DCC was protective against motor scores below 85 on the Bayley Scales of Infant Development, Third Edition (OR 0.32, 95% CI 0.10-0.90, P = .03). There were more women with preeclampsia in the ICC group (37% vs 22%, P = .02) and more women in the DCC group with premature rupture of membranes/preterm labor (54% vs 75%, P = .002). Preeclampsia halved the risk of IVH (OR 0.50, 95% CI 0.2-1.0) and premature rupture of membranes/preterm labor doubled the risk of IVH (OR 2.0, 95% CI 1.2-4.3). Conclusions: Although DCC did not alter the incidence of IVH or LOS in preterm infants, it improved motor function at 18-22 months corrected age
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