17,666 research outputs found
A Qualitative Study Using Community Cultural Wealth to Understand the Educational Experiences of Latino College Students
The Latino population is the largest minority group in the United States (Quijada & Alvarez, 2006) and has the highest high school dropout rate of any ethnic group (American Council on Education, 2008). If the U.S. is to compete in the global economy, it is important to understand factors that facilitate or hider the academic performance of Latino students. This qualitative study provides rich narratives on how Latino students used community cultural wealth, including knowledge, skills, abilities and networks, to excel in educational settings and overcome obstacles. A total of 15 individuals participated in the study. Findings suggest that Latino students overcome structural and cultural obstacles using various forms of community cultural wealth. In addition, the article provides recommendations based on participantâs experiences and previous research to increase Latino studentsâ success. It is the hope of the authors that findings from the present study will provide insight into the factors that facilitate Latino student success
Ballistic Localization in Quasi-1D Waveguides with Rough Surfaces
Structure of eigenstates in a periodic quasi-1D waveguide with a rough
surface is studied both analytically and numerically. We have found a large
number of "regular" eigenstates for any high energy. They result in a very slow
convergence to the classical limit in which the eigenstates are expected to be
completely ergodic. As a consequence, localization properties of eigenstates
originated from unperturbed transverse channels with low indexes, are strongly
localized (delocalized) in the momentum (coordinate) representation. These
eigenstates were found to have a quite unexpeted form that manifests a kind of
"repulsion" from the rough surface. Our results indicate that standard
statistical approaches for ballistic localization in such waveguides seem to be
unappropriate.Comment: 5 pages, 4 figure
Dark photon searches with atomic transitions
Dark matter could be made up of dark photons, massive but very light
particles whose interactions with matter resemble those of usual photons but
suppressed by a small mixing parameter. We analyze the main approaches to dark
photon interactions and how they can be applied to direct detection experiments
which test different ranges of masses and mixings. A new experiment based on
counting dark photons from induced atomic transitions in a target material is
proposed. This approach appears to be particularly appropriate for dark photon
detection in the meV mass range, extending the constraints in the mixing
parameter by up to eight orders of magnitude with respect to previous
experiments.Comment: 16 pages, 3 figure
Nonlinear waves in heterogeneous elastic rods via homogenization
We consider the propagation of a planar loop on a heterogeneous elastic rod with a periodic microstructure consisting of two alternating homogeneous regions with different material properties. The analysis is carried out using a second-order homogenization theory based on a multiple scale asymptotic expansion
The small behavior of the gluon structure function from total cross sections
Within a QCD-based eikonal model with a dynamical infrared gluon mass scale
we discuss how the small behavior of the gluon distribution function at
moderate is directly related to the rise of total hadronic cross
sections. In this model the rise of total cross sections is driven by
gluon-gluon semihard scattering processes, where the behavior of the small
gluon distribution function exhibits the power law . Assuming that the scale is proportional to the
dynamical gluon mass one, we show that the values of obtained in this
model are compatible with an earlier result based on a specific nonperturbative
Pomeron model. We discuss the implications of this picture for the behavior of
input valence-like gluon distributions at low resolution scales.Comment: 19 pages, 3 figures; revised version; to appear in Int. J. Mod. Phys.
The use of Planetary Nebulae precursors in the study of Diffuse Interstellar Bands
We present the first results of a systematic search for Diffuse Interstellar
Bands in a carefully selected sample of post-AGB stars observed with high
resolution optical spectroscopy. These stars are shown to be ideal targets to
study this old, intriguing astrophysical problem. Our results suggest that the
carrier(s) of these bands may not be present in the circumstellar environments
of these evolved stars. The implications of the results obtained on the
identification of the still unknown carrier(s) are discussed.Comment: 4 pages, 2 figures, proceedings of the conference 'Planetary Nebulae
as Astrophysical Tools', held in Gdansk, Poland (June 28 - July 2, 2005
The 125 GeV boson: A composite scalar?
Assuming that the 125 GeV particle observed at the LHC is a composite scalar
and responsible for the electroweak gauge symmetry breaking, we consider the
possibility that the bound state is generated by a non-Abelian gauge theory
with dynamically generated gauge boson masses and a specific chiral symmetry
breaking dynamics motivated by confinement. The scalar mass is computed with
the use of the Bethe-Salpeter equation and its normalization condition as a
function of the SU(N) group and the respective fermionic representation. If the
fermions that form the composite state are in the fundamental representation of
the SU(N) group, we can generate such light boson only for one specific number
of fermions for each group. In the case of small groups, like SU(2) to SU(5),
and two fermions in the adjoint representation we find that is quite improbable
to generate such light composite scalar.Comment: 24 pages, 5 figures, discussion extended, references added; version
to appear in Phys. Rev.
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