67,199 research outputs found
Numerical integration and other techniques for computer aided network design programming Final technical report, 1 Jan. 1970 - 1 Jan. 1971
Matrix method and stiffly stable algorithms in numerical integration for computer aided network design programmin
Maternal methadone use in pregnancy : factors associated with the development of neonatal abstinence syndrome and implications for healthcare resources
The objectives of this study were to investigate factors associated with the development of neonatal abstinence syndrome (NAS) and to assess the implications for healthcare resources of infants born to drug-misusing women. Design. Retrospective cohort study from 1 January 2004 to 31 December 2006. Setting. Inner-city maternity hospital providing dedicated multidisciplinary care to drug-misusing women. Four hundred and fifty singleton pregnancies of drugmisusing women prescribed substitute methadone in pregnancy. Development of NAS and duration of infant hospital stay. 45.5% of infants developed NAS requiring pharmacological treatment. The odds ratio of the infant developing NAS was independently related to prescribed maternal methadone dose rather than associated polydrug misuse. Breastfeeding was associated with reduced odds of requiring treatment for NAS (OR 0.55, 95% CI 0.34-0.88). Preterm birth did not influence the odds of the infant receiving treatment for NAS. 48.4% infants were admitted to the neonatal unit (NNU) 40% of these primarily for treatment of NAS. The median total hospital stay for all infants was 10 days (interquartile range 7-17 days). Infants born to methadone-prescribed drug-misusing mothers represented 2.9% of hospital births, but used 18.2% of NNU cot days. Higher maternal methadone dose is associated with a higher incidence of NAS. Pregnant drug-misusing women should be encouraged and supported to breastfeed. Their infants are extremely vulnerable and draw heavily on healthcare resources
Variation of the broad X-ray iron line in MCG-6-30-15 during a flare
We report results on the broad iron emission line of the Seyfert galaxy
MCG-6-30-15, obtained from the second long ASCA observation in 1997. The
time-averaged profile of the broad line is very similar to that seen with ASCA
in 1994, so confirming the detailed model fit then obtained. A bright flare is
seen in the light curve, during which the continuum was soft. At that time the
emission line peaks around 5 keV and most of its emission is shifted below 6
keV with no component detected at 6.4 keV (EW<60 eV). This can be interpreted
as the result of an extraordinarily large gravitational redshift due to a
dominant flare occurring very close to the black hole at a radius of <5m.Comment: 5 pages, accepted or publication in MNRAS Letter
NASTRAN analysis of an air storage piping system
The application of NASTRAN to a complex piping design evaluation problem is summarized. Emphasis is placed on structural modeling aspects, problems encountered in modeling and analyzing curved pipe sections, principal results, and relative merits of using NASTRAN as a pipe analysis and design tool. In addition, the piping and manifolding system was analyzed with SNAP (Structural Network Analysis Program). The parallel SNAP study provides a basis for limited comparisons between NASTRAN and SNAP as to solution agreement and computer execution time and costs
Subarcsecond Imaging of the NGC 6334 I(N) Protocluster: Two Dozen Compact Sources and a Massive Disk Candidate
Using the SMA and VLA, we have imaged the massive protocluster NGC6334I(N) at
high angular resolution (0.5"~650AU) from 6cm to 0.87mm, detecting 18 new
compact continuum sources. Three of the new sources are coincident with
previously-identified water masers. Together with the previously-known sources,
these data bring the number of likely protocluster members to 25 for a
protostellar density of ~700 pc^-3. Our preliminary measurement of the
Q-parameter of the minimum spanning tree is 0.82 -- close to the value for a
uniform volume distribution. All of the (nine) sources with detections at
multiple frequencies have SEDs consistent with dust emission, and two (SMA1b
and SMA4) also have long wavelength emission consistent with a central
hypercompact HII region. Thermal spectral line emission, including CH3CN, is
detected in six sources: LTE model fitting of CH3CN(J=12-11) yields
temperatures of 72-373K, confirming the presence of multiple hot cores. The
fitted LSR velocities range from -3.3 to -7.0 km/s, with an unbiased mean
square deviation of 2.05 km/s, implying a dynamical mass of 410+-260 Msun for
the protocluster. From analysis of a wide range of hot core molecules, the
kinematics of SMA1b are consistent with a rotating, infalling Keplerian disk of
diameter 800AU and enclosed mass of 10-30 Msun that is perpendicular (within 1
degree) to the large-scale bipolar outflow axis. A companion to SMA1b at a
projected separation of 0.45" (590AU; SMA1d), which shows no evidence of
spectral line emission, is also confirmed. Finally, we detect one 218.440GHz
and several 229.7588GHz Class-I methanol masers.Comment: 54 pages, 11 figures. Accepted for publication in The Astrophysical
Journal. Version 2: Keywords updated, and three "in press" citations updated
to journal reference. Version 3: corrected the error in the quantum numbers
of the 218 GHz methanol transition in the text and in Table 8. For a PDF
version with full-resolution figures, see
http://www.cv.nrao.edu/~thunter/papers/ngc6334in2014.pd
Panel Data Models with Multiple Time-Varying Individual Effects
This paper considers a panel data model with time-varying individual effects. The data are assumed to contain a large number of cross-sectional units repeatedly observed over a fixed number of time periods. The model has a feature of the fixed-effects model in that the effects are assumed to be correlated with the regressors. The unobservable individual effects are assumed to have a factor structure. For consistent estimation of the model, it is important to estimate the true number of factors. We propose a generalized methods of moments procedure by which both the number of factors and the regression coefficients can be consistently estimated. Some important identification issues are also discussed. Our simulation results indicate that the proposed methods produce reliable estimates.panel data, time-varying individual effects, factor models
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