239 research outputs found
Fitting Age-Period-Cohort Models Using the Intrinsic Estimator: Assumptions and Misapplications
We thank Demographyâs editorial office for the opportunity to respond to te Grotenhuis et al.âs commentary regarding the methods used and the results presented in our earlier paper (Masters et al. 2014). In this response, we briefly reply to three general themes raised in the commentary: (1) the presentation and discussion of APC results, (2) the fitting of full APC models to data for which a simpler model holds, and (3) the variation in the estimated age, period, and cohort coefficients produced by the intrinsic estimator (IE) (i.e., the ânon-uniqueness propertyâ of the IE, as referred to by Pelzer et al. (2015))
Effects of Home Exercise on Immediate and Delayed Affect and Mood Among Rural Individuals at Risk for Type 2 Diabetes
Physical activity is important for reducing overweight and obesity and related health consequences. This study examined changes in mood following 16 weeks of exercise in a sample of 29 individuals residing in a rural area and at risk for developing Type 2 diabetes mellitus (T2DM). Significant positive mood changes were detected, with moderate to large effect sizes. Assessments also revealed significant delayed postexercise positive emotion changes. These findings extend research on the mood benefits of exercise to individuals residing in rural settings and at risk for T2DM and suggest that to gain a full understanding of the exercise-affect relation, investigators need to assess affect at delayed intervals following exercise
Physical Properties of Emission-Line Galaxies at z ~ 2 from Near-Infrared Spectroscopy with Magellan FIRE
We present results from near-infrared spectroscopy of 26 emission-line
galaxies at z ~ 2 obtained with the FIRE spectrometer on the Magellan Baade
telescope. The sample was selected from the WISP survey, which uses the
near-infrared grism of the Hubble Space Telescope Wide Field Camera 3 to detect
emission-line galaxies over 0.3 < z < 2.3. Our FIRE follow-up spectroscopy
(R~5000) over 1.0-2.5 micron permits detailed measurements of physical
properties of the z~2 emission-line galaxies. Dust-corrected star formation
rates for the sample range from ~5-100 M_sun yr-1. We derive a median
metallicity for the sample of ~0.45 Z_sun, and the estimated stellar masses
range from ~10^8.5 - 10^9.5 M_sun. The average ionization parameters measured
for the sample are typically much higher than what is found for local
star-forming galaxies. We derive composite spectra from the FIRE sample, from
which we infer typical nebular electron densities of ~100-400 cm^-3. Based on
the location of the galaxies and composite spectra on BPT diagrams, we do not
find evidence for significant AGN activity in the sample. Most of the galaxies
as well as the composites are offset in the BPT diagram toward higher [O
III]/H-beta at a given [N II]/H-alpha, in agreement with other observations of
z > 1 star-forming galaxies, but composite spectra derived from the sample do
not show an appreciable offset from the local star-forming sequence on the [O
III]/H-beta versus [S II]/H-alpha diagram. We infer a high nitrogen-to-oxygen
abundance ratio from the composite spectrum, which may contribute to the offset
of the high-redshift galaxies from the local star-forming sequence in the [O
III]/H-beta versus [N II]/H-alpha diagram. We speculate that the elevated
nitrogen abundance could result from substantial numbers of Wolf-Rayet stars in
starbursting galaxies at z~2. (Abridged)Comment: Accepted for publication in Ap
The Arecibo Legacy Fast ALFA Survey: VI. Second HI Source Catalog of the Virgo Cluster Region
We present the third installment of HI sources extracted from the Arecibo
Legacy Fast ALFA extragalactic survey. This dataset continues the work of the
Virgo ALFALFA catalog. The catalogs and spectra published here consist of data
obtained during the 2005 and 2006 observing sessions of the survey. The catalog
consists of 578 HI detections within the range 11h 36m < R.A.(J2000) < 13h 52m
and +08 deg < Dec.(J2000) < +12 deg, and cz_sun < 18000 km/s. The catalog
entries are identified with optical counterparts where possible through the
examination of digitized optical images. The catalog detections can be
classified into three categories: (a) detections of high reliability with S/N >
6.5; (b) high velocity clouds in the Milky Way or its periphery; and (c)
signals of lower S/N which coincide spatially with an optical object and known
redshift. 75% of the sources are newly published HI detections. Of particular
note is a complex of HI clouds projected between M87 and M49 that do not
coincide with any optical counterparts. Candidate objects without optical
counterparts are few. The median redshift for this sample is 6500 km/s and the
cz distribution exhibits the local large scale structure consisting of Virgo
and the background void and the A1367-Coma supercluster regime at cz_sun ~7000
km/s. Position corrections for telescope pointing errors are applied to the
dataset by comparing ALFALFA continuum centroid with those cataloged in the
NRAO VLA Sky Survey. The uncorrected positional accuracy averages
27 arcsec ~(21 arcsec ~median) for all sources with S/N > 6.5 and is of order
~21 arcsec ~(16 arcsec ~median) for signals with S/N > 12. Uncertainties in
distances toward the Virgo cluster can affect the calculated HI mass
distribution.Comment: 25 pages, 1 Table, 8 figures, Accepted by the Astronomical Journa
The Arecibo Legacy Fast ALFA Survey: III. HI Source Catalog of the Northern Virgo Cluster Region
We present the first installment of HI sources extracted from the Arecibo
Legacy Fast ALFA (ALFALFA) extragalactic survey, initiated in 2005. Sources
have been extracted from 3-D spectral data cubes and then examined
interactively to yield global HI parameters. A total of 730 HI detections are
catalogued within the solid angle 11h44m < R.A.(J2000) < 14h00m and +12deg <
Dec.(J2000) < +16deg, and redshift range -1600 \kms < cz < 18000 \kms. In
comparison, the HI Parkes All-Sky Survey (HIPASS) detected 40 HI signals in the
same region. Optical counterparts are assigned via examination of digital
optical imaging databases. ALFALFA HI detections are reported for three
distinct classes of signals: (a) detections, typically with S/N > 6.5; (b) high
velocity clouds in the Milky Way or its periphery; and (c) signals of lower S/N
(to ~ 4.5) which coincide spatially with an optical object of known similar
redshift. Although this region of the sky has been heavily surveyed by previous
targeted observations based on optical flux-- or size-- limited samples, 69% of
the extracted sources are newly reported HI detections. The resultant
positional accuracy of HI sources is 20" (median). The median redshift of the
sample is ~7000 \kms and its distribution reflects the known local large scale
structure including the Virgo cluster. Several extended HI features are found
in the vicinity of the Virgo cluster. A small percentage (6%) of HI detections
have no identifiable optical counterpart, more than half of which are high
velocity clouds in the Milky Way vicinity; the remaining 17 objects do not
appear connected to or associated with any known galaxy.Comment: Astronomical Journal, in pres
Comparison of Pittsburgh compound B and florbetapir in cross-sectional and longitudinal studies.
IntroductionQuantitative in vivo measurement of brain amyloid burden is important for both research and clinical purposes. However, the existence of multiple imaging tracers presents challenges to the interpretation of such measurements. This study presents a direct comparison of Pittsburgh compound B-based and florbetapir-based amyloid imaging in the same participants from two independent cohorts using a crossover design.MethodsPittsburgh compound B and florbetapir amyloid PET imaging data from three different cohorts were analyzed using previously established pipelines to obtain global amyloid burden measurements. These measurements were converted to the Centiloid scale to allow fair comparison between the two tracers. The mean and inter-individual variability of the two tracers were compared using multivariate linear models both cross-sectionally and longitudinally.ResultsGlobal amyloid burden measured using the two tracers were strongly correlated in both cohorts. However, higher variability was observed when florbetapir was used as the imaging tracer. The variability may be partially caused by white matter signal as partial volume correction reduces the variability and improves the correlations between the two tracers. Amyloid burden measured using both tracers was found to be in association with clinical and psychometric measurements. Longitudinal comparison of the two tracers was also performed in similar but separate cohorts whose baseline amyloid load was considered elevated (i.e., amyloid positive). No significant difference was detected in the average annualized rate of change measurements made with these two tracers.DiscussionAlthough the amyloid burden measurements were quite similar using these two tracers as expected, difference was observable even after conversion into the Centiloid scale. Further investigation is warranted to identify optimal strategies to harmonize amyloid imaging data acquired using different tracers
The Arecibo Legacy Fast ALFA Survey: The alpha.40 HI Source Catalog, its Characteristics and their Impact on the Derivation of the HI Mass Function
We present a current catalog of 21 cm HI line sources extracted from the
Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) survey over ~2800
square degrees of sky: the alpha.40 catalog. Covering 40% of the final survey
area, the alpha.40 catalog contains 15855 sources in the regions 07h30m < R.A.
< 16h30m, +04 deg < Dec. < +16 deg and +24 deg < Dec. < +28 deg and 22h < R.A.
< 03h, +14 deg < Dec. < +16 deg and +24 deg < Dec. < +32 deg. Of those, 15041
are certainly extragalactic, yielding a source density of 5.3 galaxies per
square degree, a factor of 29 improvement over the catalog extracted from the
HI Parkes All Sky Survey. In addition to the source centroid positions, HI line
flux densities, recessional velocities and line widths, the catalog includes
the coordinates of the most probable optical counterpart of each HI line
detection, and a separate compilation provides a crossmatch to identifications
given in the photometric and spectroscopic catalogs associated with the Sloan
Digital Sky Survey Data Release 7. Fewer than 2% of the extragalactic HI line
sources cannot be identified with a feasible optical counterpart; some of those
may be rare OH megamasers at 0.16 < z < 0.25. A detailed analysis is presented
of the completeness, width dependent sensitivity function and bias inherent in
the current alpha.40 catalog. The impact of survey selection, distance errors,
current volume coverage and local large scale structure on the derivation of
the HI mass function is assessed. While alpha.40 does not yet provide a
completely representative sampling of cosmological volume, derivations of the
HI mass function using future data releases from ALFALFA will further improve
both statistical and systematic uncertainties.Comment: 62 pages, 28 figures. See http://egg.astro.cornell.edu/alfalfa/data
for ASCII and CSV datafiles corresponding to Tables 1, 2 and 3. A higher
resolution PDF version can be found at
http://egg.astro.cornell.edu/alfalfa/pubs.php. To appear in Nov 2011 Astron.
Pharmacokinetic modeling of R and S-Methadone and their metabolites to study the effects of various covariates in post-operative children
Methadone is a synthetic opioid used as an analgesic and for the treatment of opioid abuse disorder. The analgesic dose in the pediatric population is not well-defined. The pharmacokinetics (PKs) of methadone is highly variable due to the variability in alpha-1 acid glycoprotein (AAG) and genotypic differences in drug-metabolizing enzymes. Additionally, the R and S enantiomers of methadone have unique PK and pharmacodynamic properties. This study aims to describe the PKs of R and S methadone and its metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in pediatric surgical patients and to identify sources of inter- and intra-individual variability. Children aged 8-17.9 years undergoing orthopedic surgeries received intravenous methadone 0.1 mg/kg intra-operatively followed by oral methadone 0.1 mg/kg postoperatively every 12 h. Pharmacokinetics of R and S methadone and EDDP were determined using liquid chromatography tandem mass spectrometry assays and the data were modeled using nonlinear mixed-effects modeling in NONMEM. R and S methadone PKs were well-described by two-compartment disposition models with first-order absorption and elimination. EDDP metabolites were described by one compartment disposition models with first order elimination. Clearance of both R and S methadone were allometrically scaled by bodyweight. CYP2B6 phenotype was a determinant of the clearance of both the enantiomers in an additive gene model. The intronic CYP3A4 single-nucleotide polymorphism (SNP) rs2246709 was associated with decreased clearance of R and S methadone. Concentrations of AAG and the SNP of AAG rs17650 independently increased the volume of distribution of both the enantiomers. The knowledge of these important covariates will aid in the optimal dosing of methadone in children
The ALMA Interferometric Pipeline Heuristics
We describe the calibration and imaging heuristics developed and deployed in
the ALMA interferometric data processing pipeline, as of ALMA Cycle 9. The
pipeline software framework is written in Python, with each data reduction
stage layered on top of tasks and toolkit functions provided by the Common
Astronomy Software Applications package. This framework supports a variety of
tasks for observatory operations, including science data quality assurance,
observing mode commissioning, and user reprocessing. It supports ALMA and VLA
interferometric data along with ALMA and NRO45m single dish data, via different
stages and heuristics. In addition to producing calibration tables, calibrated
measurement sets, and cleaned images, the pipeline creates a WebLog which
serves as the primary interface for verifying the data quality assurance by the
observatory and for examining the contents of the data by the user. Following
the adoption of the pipeline by ALMA Operations in 2014, the heuristics have
been refined through annual development cycles, culminating in a new pipeline
release aligned with the start of each ALMA Cycle of observations. Initial
development focused on basic calibration and flagging heuristics (Cycles 2-3),
followed by imaging heuristics (Cycles 4-5), refinement of the flagging and
imaging heuristics with parallel processing (Cycles 6-7), addition of the
moment difference analysis to improve continuum channel identification (2020
release), addition of a spectral renormalization stage (Cycle 8), and
improvement in low SNR calibration heuristics (Cycle 9). In the two most recent
Cycles, 97% of ALMA datasets were calibrated and imaged with the pipeline,
ensuring long-term automated reproducibility. We conclude with a brief
description of plans for future additions, including self-calibration,
multi-configuration imaging, and calibration and imaging of full polarization
data.Comment: accepted for publication by Publications of the Astronomical Society
of the Pacific, 65 pages, 20 figures, 10 tables, 2 appendice
MESSENGER orbital observations of largeâamplitude KelvinâHelmholtz waves at Mercury's magnetopause
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95418/1/jgra21747.pd
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