1,941 research outputs found
Public Policies and Women's Employment after Childbearing
This paper examines how the public policy environment in the United States affects work by new mothers following childbirth. We examine four types of policies that vary across states and affect the budget constraint in different ways. The policy environment has important effects, particularly for less advantaged mothers. There is a potential conflict between policies aiming to increase maternal employment and those maximizing the choices available to families with young children. However, this tradeoff is not absolute since some choice-increasing policies (generous child care subsidies and state parental leave laws) foster both choice and higher levels of employment.public policies, maternal employment, childbearing
A Longitudinal Mixed Logit Model for Estimation of Push and Pull Effects in Residential Location Choice
We develop a random effects discrete choice model for the analysis of households' choice of neighbourhood over time. The model is parameterised in a way that exploits longitudinal data to separate the influence of neighbourhood characteristics on the decision to move out of the current area (\push" effects) and on the choice of one destination over another (\pull" efdfects). Random effects are included to allow for unobserved heterogeneity between households in their propensity to move, and in the importance placed on area characteristics. The model also includes area-level random effects. The combination of a large choice set, large sample size and repeated observations mean that existing estimation approaches are often infeasible. We therefore propose an effcient MCMC algorithm for the analysis of large-scale datasets. The model is applied in an analysis of residential choice in England using data from the British Household Panel Survey linked to neighbourhood-level census data. We consider how effects of area deprivation and distance from the current area depend on household characteristics and life course transitions in the previous year. We find substantial differences between households in the effects of deprivation on out-mobility and selection of destination, with evidence of severely constrained choices among less-advantaged households
Establishing Applicability of SSDs to LHC Tier-2 Hardware Configuration
Solid State Disk technologies are increasingly replacing high-speed hard
disks as the storage technology in high-random-I/O environments. There are
several potentially I/O bound services within the typical LHC Tier-2 - in the
back-end, with the trend towards many-core architectures continuing, worker
nodes running many single-threaded jobs and storage nodes delivering many
simultaneous files can both exhibit I/O limited efficiency. We estimate the
effectiveness of affordable SSDs in the context of worker nodes, on a large
Tier-2 production setup using both low level tools and real LHC I/O intensive
data analysis jobs comparing and contrasting with high performance spinning
disk based solutions. We consider the applicability of each solution in the
context of its price/performance metrics, with an eye on the pragmatic issues
facing Tier-2 provision and upgradesComment: 6 pages, 1 figure, 4 tables. Conference proceedings for CHEP201
Comparative effect of ALA derivatives on protoporphyrin IX production in human and rat skin organ cultures
Samples of human and rat skin in short-term organ culture exposed to ALA or a range of hydrophobic derivatives were examined for their effect on the accumulation of protoporphyrin IX (PpIX) measured using fluorescence spectroscopy. With the exception of carbobenzoyloxy-D-phenylalanyl-5-ALA-ethyl ester the data presented indicate that, in normal tissues, ALA derivatives generate protoporphyrin IX more slowly than ALA, suggesting that they are less rapidly taken up and/or converted to free ALA. However, the resultant depot effect may lead to the enhanced accumulation of porphyrin over long exposure periods, particularly in the case of ALA-methyl ester or ALA-hexyl ester, depending on the applied concentration and the exposed tissue. Addition of the iron chelator, CP94, greatly increased PpIX accumulation in human skin exposed to ALA, ALA-methyl ester and ALA-hexyl ester. The effect in rat skin was less marked.</p
Searches for supersymmetric particles in collisions up to 208 GeV and interpretation of the results within the MSSM
Study of Leading Hadrons in Gluon and Quark Fragmentation
The study of quark jets in e+e- reactions at LEP has demonstrated that the
hadronisation process is reproduced well by the Lund string model. However, our
understanding of gluon fragmentation is less complete. In this study enriched
quark and gluon jet samples of different purities are selected in three-jet
events from hadronic decays of the Z collected by the DELPHI experiment in the
LEP runs during 1994 and 1995. The leading systems of the two kinds of jets are
defined by requiring a rapidity gap and their sum of charges is studied. An
excess of leading systems with total charge zero is found for gluon jets in all
cases, when compared to Monte Carlo Simulations with JETSET (with and without
Bose-Einstein correlations included) and ARIADNE. The corresponding leading
systems of quark jets do not exhibit such an excess. The influence of the gap
size and of the gluon purity on the effect is studied and a concentration of
the excess of neutral leading systems at low invariant masses (<~ 2 GeV/c^2) is
observed, indicating that gluon jets might have an additional hitherto
undetected fragmentation mode via a two-gluon system. This could be an
indication of a possible production of gluonic states as predicted by QCD.Comment: 19 pages, 6 figures, Accepted by Phys. Lett.
Searches for supersymmetric particles in collisions up to 208 GeV, and interpretation of the results within the MSSM
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