33,740 research outputs found
Household income as a determinant of child labor and school enrollment in Brazil: Evidence from a social security reform
This paper studies the effects of household income on labor participation and school enrollment of children aged 10 to 14 in Brazil using a social security reform as a source of exogenous variation in household income. We find that increased benefits are associated with increases in school enrollment for girls, as well as a smaller reduction in their labor participation, but find no effects for boys. We also uncover evidence that the gender of the benefit receiver matters for girlsâ labor variables: only benefits received by females reduce girlsâ work.social security reform, child labor, family, school enrollment, old-age benefits, Brazil
Three-dimensional quantum electrodynamics as an effective interaction
We obtain a Quantum Electrodynamics in 2+1 dimensions by applying a
Kaluza--Klein type method of dimensional reduction to Quantum Electrodynamics
in 3+1 dimensions rendering the model more realistic to application in
solid-state systems, invariant under translations in one direction. We show
that the model obtained leads to an effective action exhibiting an interesting
phase structure and that the generated Chern--Simons term survives only in the
broken phase.Comment: 10 pages in Plain Te
The Role of Fermions in Bubble Nucleation
We present a study of the role of fermions in the decay of metastable states
of a scalar field via bubble nucleation. We analyze both one and
three-dimensional systems by using a gradient expansion for the calculation of
the fermionic determinant. The results of the one-dimensional case are compared
to the exact results of previous work.Comment: 15 pages, revtex, 9 figure
Characterizing the nature of Fossil Groups with XMM
We present an X-ray follow-up, based on XMM plus Chandra, of six Fossil Group
(FG) candidates identified in our previous work using SDSS and RASS data. Four
candidates (out of six) exhibit extended X-ray emission, confirming them as
true FGs. For the other two groups, the RASS emission has its origin as either
an optically dull/X-ray bright AGN, or the blending of distinct X-ray sources.
Using SDSS-DR7 data, we confirm, for all groups, the presence of an r-band
magnitude gap between the seed elliptical and the second-rank galaxy. However,
the gap value depends, up to 0.5mag, on how one estimates the seed galaxy total
flux, which is greatly underestimated when using SDSS (relative to Sersic)
magnitudes. This implies that many FGs may be actually missed when using SDSS
data, a fact that should be carefully taken into account when comparing the
observed number densities of FGs to the expectations from cosmological
simulations. The similarity in the properties of seed--FG and non-fossil
ellipticals, found in our previous study, extends to the sample of X-ray
confirmed FGs, indicating that bright ellipticals in FGs do not represent a
distinct population of galaxies. For one system, we also find that the velocity
distribution of faint galaxies is bimodal, possibly showing that the system
formed through the merging of two groups. This undermines the idea that all
selected FGs form a population of true fossils.Comment: 9 pages, 3 figures. Submitted 01/12/2011 to MNRAS, referee report
received 21/02/2012, accepted 22/02/201
Weak measurement og the composite Goo-Haenchen shift in the critical region
By using a weak measurement technique, we investigated the interplay between
the angular and lateral Goos-Haenchen shift of a focused He-Ne laser beam for
incidence near the critical angle. We verified that this interplay dramatically
affects the composite Goos-Haenchen shift of the propagated beam. The
experimental results confirm theoretical predictions that recently appeared in
the literature.Comment: 10 pages, 3 figure
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