13,776 research outputs found
Ecojusticia, equidad y ética: retos para la orientación educativa y profesional
In social and environmental terms we live in precarious and uncertain times, where not only the sustainability of the
planet rests in the balance, but also that of human existence. Many nation-states around the world talk of the
importance of social cohesion, and are aware of the threat of environmental degradation, climate change, and
ecological well-being. However, the dominating global policy discourse, particularly championed in the West, is
located within a delimiting neo/liberal political framework. With a few noticeable exceptions, the influence of
neo/liberal thinking continues to flourish in the contemporary career literature where there has been little deep
critical engagement with the discourse of capitalist economics and how these impact human and environmental
well-being. Often caught up in market-led discourses, and captured by the notion that ‘work sets you free’,
educational and career guidance has been located within an uncritical economic frame. Its energies tend to be
directed towards the preparation of individuals to make ‘good’ educational and occupational choices, underpinned
by the need for ‘clients’ to acquire the skills and competencies demanded by employers (and the economy)
(Bengtsson, 2011; Irving, 2018). The disjuncture between educational and career guidance and social and
environmental justice (i.e. ecojustice) has rarely been breached. In this article, we seek to disrupt dominant
discourses of the market that currently permeates thinking in education by identifying how an ecojustice
perspective provides a forward looking and equitable foundation for educational and career guidance.En términos sociales y ambientales, vivimos en tiempos precarios e inciertos, donde no solo la sostenibilidad del
planeta está en juego, sino también la de la existencia humana. Muchos estados-nación de todo el mundo hablan de
la importancia de la cohesión social y son conscientes de la degradación ambiental, el cambio climático y la amenaza
al bienestar ecológico y social. Sin embargo, el discurso dominante de la polÃtica global, particularmente defendido
en Occidente, se sitúa dentro de un marco polÃtico neoliberal. Con algunas notables excepciones, la influencia del
pensamiento neoliberal continúa siendo hegemónico en el campo de la educación y de la orientación profesional,
donde en términos generales ha habido poco compromiso crÃtico profundo con el discurso de la economÃa capitalista
y cómo este impacta sobre el bienestar humano y ambiental. A menudo atrapada en discursos dirigidos por el mercado
y por la noción de que "el trabajo nos hace libres", la orientación educativa y profesional se ha ubicado dentro de un
marco económico acrÃtico. Se tiende a preparar a los individuos para tomar "buenas" decisiones educativas y
ocupacionales, respaldadas por la necesidad de que adquieran las habilidades y competencias exigidas por los
empleadores (y la economÃa) (Bengtsson, 2011; Irving, 2018). La disyuntiva entre la orientación educativa y
profesional y la justicia social y ambiental (la ecojusticia) rara vez se ha abordado. En este artÃculo cuestionamos los
discursos dominantes del mercado que actualmente impregnan el pensamiento en educación, y proponemos la
adopción de una perspectiva de ecojusticia que proporciona una guÃa para el futuro y contribuye a promover la
equidad desde la orientación educativa y profesional
Perturbations in Hybrid Loop Quantum Cosmology: Continuum Limit in Fourier Space
We analyze the passage to a continuum limit of the mode spectrum of
primordial perturbations around flat cosmological spacetimes in hybrid Loop
Quantum Cosmology, showing that this limit can be reached even if one starts by
considering a finite fiducial cell as spatial slice. We focus our attention on
regimes in which the background cosmology follows the effective dynamics of
Loop Quantum Cosmology, although we comment on extensions of our arguments
beyond this regime, as well as to some formalisms other than the hybrid
approach. Whereas the perturbed system can be described in an invariant way
under changes of the fiducial volume using the standard variables of the
improved prescription for Loop Quantum Cosmology, we show that the desired
continuum limit can be established by means of scaling transformations of the
physical volume when this volume grows unboundedly. These transformations lead
to a model with a continuum of modes and independent of any scale of reference
for the physical volume. For the sake of comparison, we also consider an
alternative road to the continuum in Fourier space that has been employed in
geometrodynamics and is based on the use of scaling transformations of the
fiducial volume, together with variables that are independent of them.Comment: 13 page
Application of Species Distribution Modeling for Avian Influenza surveillance in the United States considering the North America Migratory Flyways.
Highly Pathogenic Avian Influenza (HPAI) has recently (2014-2015) re-emerged in the United States (US) causing the largest outbreak in US history with 232 outbreaks and an estimated economic impact of $950 million. This study proposes to use suitability maps for Low Pathogenic Avian Influenza (LPAI) to identify areas at high risk for HPAI outbreaks. LPAI suitability maps were based on wild bird demographics, LPAI surveillance, and poultry density in combination with environmental, climatic, and socio-economic risk factors. Species distribution modeling was used to produce high-resolution (cell size: 500m x 500m) maps for Avian Influenza (AI) suitability in each of the four North American migratory flyways (NAMF). Results reveal that AI suitability is heterogeneously distributed throughout the US with higher suitability in specific zones of the Midwest and coastal areas. The resultant suitability maps adequately predicted most of the HPAI outbreak areas during the 2014-2015 epidemic in the US (i.e. 89% of HPAI outbreaks were located in areas identified as highly suitable for LPAI). Results are potentially useful for poultry producers and stakeholders in designing risk-based surveillance, outreach and intervention strategies to better prevent and control future HPAI outbreaks in the US
Breached pairing in trapped three-color atomic Fermi gases
We introduce an exactly solvable model for trapped three-color atom gases.
Applications to a cigar-shaped trapped cold fermions reveal a complex structure
of breached pairing phases. We find two competing superfluid phases at weak and
intermediate couplings, each one with two color pair condensates, that can be
distinguished from density profile measurements.Comment: 4 pages, 5 figure
Modeling effective FRW cosmologies with perfect fluids from states of the hybrid quantum Gowdy model
We employ recently developed approximation methods in the hybrid quantization
of the Gowdy model with linear polarization and a massless scalar field
to obtain physically interesting solutions of this inhomogeneous cosmology.
More specifically, we propose approximate solutions of the quantum Gowdy model
constructed in such a way that, for the Hamiltonian constraint, they
effectively behave as those corresponding to a flat homogeneous and isotropic
universe filled with a perfect fluid, even though these quantum states are far
from being homogeneous and isotropic. We analyze how one can get different
perfect fluid effective behaviors, including the cases of dust, radiation, and
cosmological constant.Comment: Version accepted for publication in PR
Griffiths phases in the strongly disordered Kondo necklace model
The effect of strong disorder on the one-dimensional Kondo necklace model is
studied using a perturbative real-space renormalization group approach which
becomes asymptotically exact in the low energy limit. The phase diagram of the
model presents a random quantum critical point separating two phases; the {\em
random singlet phase} of a quantum disordered XY chain and the random Kondo
phase. We also consider an anisotropic version of the model and show that it
maps on the strongly disordered transverse Ising model. The present results
provide a rigorous microscopic basis for non-Fermi liquid behavior in
disordered heavy fermions due to Griffiths phases.Comment: 4 pages, 4 figure
Fermions in Hybrid Loop Quantum Cosmology
This work pioneers the quantization of primordial fermion perturbations in
hybrid Loop Quantum Cosmology (LQC). We consider a Dirac field coupled to a
spatially flat, homogeneous, and isotropic cosmology, sourced by a scalar
inflaton, and treat the Dirac field as a perturbation. We describe the
inhomogeneities of this field in terms of creation and annihilation variables,
chosen to admit a unitary evolution if the Dirac fermion were treated as a test
field. Considering instead the full system, we truncate its action at quadratic
perturbative order and construct a canonical formulation. In particular this
implies that, in the global Hamiltonian constraint of the model, the
contribution of the homogeneous sector is corrected with a quadratic
perturbative term. We then adopt the hybrid LQC approach to quantize the full
model, combining the loop representation of the homogeneous geometry with the
Fock quantization of the inhomogeneities. We assume a Born-Oppenheimer ansatz
for physical states and show how to obtain a Schr\"odinger equation for the
quantum evolution of the perturbations, where the role of time is played by the
homogeneous inflaton. We prove that the resulting quantum evolution of the
Dirac field is indeed unitary, despite the fact that the underlying homogeneous
geometry has been quantized as well. Remarkably, in such evolution, the fermion
field couples to an infinite sequence of quantum moments of the homogeneous
geometry. Moreover, the evolved Fock vacuum of our fermion perturbations is
shown to be an exact solution of the Schr\"odinger equation. Finally, we
discuss in detail the quantum backreaction that the fermion field introduces in
the global Hamiltonian constraint. For completeness, our quantum study includes
since the beginning (gauge-invariant) scalar and tensor perturbations, that
were studied in previous works.Comment: 29 pages. It matches published versio
Modified FRW cosmologies arising from states of the hybrid quantum Gowdy model
We construct approximate solutions of the hybrid quantum Gowdy cosmology with
three-torus topology, linear polarization, and local rotational symmetry, in
the presence of a massless scalar field. More specifically, we determine some
families of states for which the complicated inhomogeneous and anisotropic
Hamiltonian constraint operator of the Gowdy model is approximated by a much
simpler one. Our quantum states follow the dynamics governed by this simpler
constraint, while being at the same time also approximate solutions of the full
Gowdy model. This is so thanks to the quantum correlations that the considered
states present between the isotropic and anisotropic sectors of the model.
Remarkably, this simpler constraint can be regarded as that of a flat
Friedmann-Robertson-Walker universe filled with different kinds of perfect
fluids and geometrically corrected by homogeneous and isotropic curvature-like
terms. Therefore, our quantum states, which are intrinsically inhomogeneous,
admit approximate homogeneous and isotropic effective descriptions similar to
those considered in modified theories of gravity.Comment: Version accepted for publication in PR
XASH genes promote neurogenesis in Xenopus embryos
Neural development in Drosophila is promoted by a family of basic helix-loop-helix (bHLH) transcription factors encoded within the Achaete Scute-Complex (AS-C). XASH-
3, a Xenopus homolog of the Drosophila AS-C genes, is expressed during neural induction within a portion of the dorsal ectoderm that gives rise to the neural plate and tube. Here, we show that XASH-3, when expressed with the promiscuous binding partner XE12, specifically activates the expression of neural genes in naive ectoderm, suggesting
that XASH-3 promotes neural development. Moreover, XASH-3/XE12 RNA injections into embryos lead to hypertrophy of the neural tube. Interestingly, XASH-3 misexpression
does not lead to the formation of ectopic neural tissue in ventral regions, suggesting that the domain of XASH proneural function is restricted in the embryo. In contrast to the neural inducer noggin, which permanently activates the NCAM gene, the activation of neural genes by XASH-3/XE12 is not stable in naive ectoderm, yet XASH-3/XE12 powerfully and stably activates NCAM, Neurofilament and type III β-tubulin gene expression in noggintreated ectoderm. These results show that the XASH-3 promotes neural development, and suggest that its activity depends on additional factors which are induced in ectoderm by factors such as noggin
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