105 research outputs found
Review of \u3cem\u3eFreefall: America, Markets and the Sinking of the World Economy.\u3c/em\u3e Joseph E. Stiglitz. Reviewed by Helen Lachs Ginsburg.
Book review of Joseph E. Stiglitz, Freefall: America, Markets and the Sinking of the World Economy. New York, N.Y.: W. W. Norton, 2010. $27.95 hardcover
Review of \u3cem\u3eSocial Security Works! Why Social Security Isn\u27t Going Broke & How Expanding It Will Help Us All\u3c/em\u3e. Nancy J. Altman & Eric R. Kingson. 135 Reviewed by Helen Lachs Ginsburg
Nancy J. Altman & Eric R. Kingson, Social Security Works! Why Social Security Isn\u27t Going Broke & How Expanding It Will Help Us All. New Press (2015), 320 pages, $16.95 (paperback)
The Green Bank Ammonia Survey (GAS): First Results of NH3 mapping the Gould Belt
We present an overview of the first data release (DR1) and first-look science
from the Green Bank Ammonia Survey (GAS). GAS is a Large Program at the Green
Bank Telescope to map all Gould Belt star-forming regions with
mag visible from the northern hemisphere in emission from NH and other key
molecular tracers. This first release includes the data for four regions in
Gould Belt clouds: B18 in Taurus, NGC 1333 in Perseus, L1688 in Ophiuchus, and
Orion A North in Orion. We compare the NH emission to dust continuum
emission from Herschel, and find that the two tracers correspond closely.
NH is present in over 60\% of lines-of-sight with mag in
three of the four DR1 regions, in agreement with expectations from previous
observations. The sole exception is B18, where NH is detected toward ~ 40\%
of lines-of-sight with mag. Moreover, we find that the NH
emission is generally extended beyond the typical 0.1 pc length scales of dense
cores. We produce maps of the gas kinematics, temperature, and NH column
densities through forward modeling of the hyperfine structure of the NH
(1,1) and (2,2) lines. We show that the NH velocity dispersion,
, and gas kinetic temperature, , vary systematically between
the regions included in this release, with an increase in both the mean value
and spread of and with increasing star formation activity.
The data presented in this paper are publicly available.Comment: 33 pages, 27 figures, accepted to ApJS. Datasets are publicly
available: https://dataverse.harvard.edu/dataverse/GAS_DR
Droplets I: Pressure-Dominated Sub-0.1 pc Coherent Structures in L1688 and B18
We present the observation and analysis of newly discovered coherent
structures in the L1688 region of Ophiuchus and the B18 region of Taurus. Using
data from the Green Bank Ammonia Survey (GAS), we identify regions of high
density and near-constant, almost-thermal, velocity dispersion. Eighteen
coherent structures are revealed, twelve in L1688 and six in B18, each of which
shows a sharp "transition to coherence" in velocity dispersion around its
periphery. The identification of these structures provides a chance to study
the coherent structures in molecular clouds statistically. The identified
coherent structures have a typical radius of 0.04 pc and a typical mass of 0.4
Msun, generally smaller than previously known coherent cores identified by
Goodman et al. (1998), Caselli et al. (2002), and Pineda et al. (2010). We call
these structures "droplets." We find that unlike previously known coherent
cores, these structures are not virially bound by self-gravity and are instead
predominantly confined by ambient pressure. The droplets have density profiles
shallower than a critical Bonnor-Ebert sphere, and they have a velocity (VLSR)
distribution consistent with the dense gas motions traced by NH3 emission.
These results point to a potential formation mechanism through pressure
compression and turbulent processes in the dense gas. We present a comparison
with a magnetohydrodynamic simulation of a star-forming region, and we
speculate on the relationship of droplets with larger, gravitationally bound
coherent cores, as well as on the role that droplets and other coherent
structures play in the star formation process.Comment: Accepted by ApJ in April, 201
Ubiquitous supersonic component in L1688 coherent cores
Context : Star formation takes place in cold dense cores in molecular clouds.
Earlier observations have found that dense cores exhibit subsonic non-thermal
velocity dispersions. In contrast, CO observations show that the ambient
large-scale cloud is warmer and has supersonic velocity dispersions. Aims : We
aim to study the ammonia () molecular line profiles with exquisite
sensitivity towards the coherent cores in L1688 in order to study their
kinematical properties in unprecedented detail. Methods : We used
(1,1) and (2,2) data from the first data release (DR1) in the Green Bank
Ammonia Survey (GAS). We first smoothed the data to a larger beam of 1' to
obtain substantially more extended maps of velocity dispersion and kinetic
temperature, compared to the DR1 maps. We then identified the coherent cores in
the cloud and analysed the averaged line profiles towards the cores. Results :
For the first time, we detected a faint (mean (1,1) peak brightness
0.25 K in ), supersonic component towards all the coherent cores in
L1688. We fitted two components, one broad and one narrow, and derived the
kinetic temperature and velocity dispersion of each component. The broad
components towards all cores have supersonic linewidths (). This component biases the estimate of the narrow dense core component's
velocity dispersion by 28% and the kinetic temperature by
10%, on average, as compared to the results from single-component
fits. Conclusions : Neglecting this ubiquitous presence of a broad component
towards all coherent cores causes the typical single-component fit to
overestimate the temperature and velocity dispersion. This affects the derived
detailed physical structure and stability of the cores estimated from observations.Comment: Accepted for publication in Astronomy & Astrophysics on 06/07/2020.
15 pages, 16 figures, 1 table. Language edits from previous versio
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Young children have social worries too: validation of a brief parent report measure of social worries in children aged 4–8 years
This study investigated the psychometric properties of the Social Worries Anxiety Index for Young children (SWAIY), adapted from the Social Worries Questionnaire—Parent version (SWQ-P; Spence, 1995), as a measure of social anxiety in young children. 169 parents of children aged four to eight years from a community sample completed the SWAIY and a standardized measure of anxiety; the SWAIY was completed again two weeks later. Parents deemed the items appropriate and relevant to children of this age. The SWAIY demonstrated excellent ( > 0.80) internal consistency and a one-factor model. Test-retest reliability was strong (r = 0.87) and evidence of convergent validity (r > .50) was found. The study provides initial evidence for the validation of SWAIY as a measure of social anxiety in children aged four to eight years old. This questionnaire is ideal for investigating social anxiety over early childhood and the relationship between early social worries and later anxiety disorders
The Roles of Youth in Society: A Reconceptualization
The 1980s have been characterized as a decade of platforms for educational change. In 19S3 alone, five reports were released by national task forces and commissions, all expressing serious concern for the future of youth and society, and all proposing recommendations for ways in which educational policies and practices might be altered, to address such concerns
Measurement of inclusive D*+- and associated dijet cross sections in photoproduction at HERA
Inclusive photoproduction of D*+- mesons has been measured for photon-proton
centre-of-mass energies in the range 130 < W < 280 GeV and a photon virtuality
Q^2 < 1 GeV^2. The data sample used corresponds to an integrated luminosity of
37 pb^-1. Total and differential cross sections as functions of the D*
transverse momentum and pseudorapidity are presented in restricted kinematical
regions and the data are compared with next-to-leading order (NLO) perturbative
QCD calculations using the "massive charm" and "massless charm" schemes. The
measured cross sections are generally above the NLO calculations, in particular
in the forward (proton) direction. The large data sample also allows the study
of dijet production associated with charm. A significant resolved as well as a
direct photon component contribute to the cross section. Leading order QCD
Monte Carlo calculations indicate that the resolved contribution arises from a
significant charm component in the photon. A massive charm NLO parton level
calculation yields lower cross sections compared to the measured results in a
kinematic region where the resolved photon contribution is significant.Comment: 32 pages including 6 figure
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