2,636 research outputs found
"Non, moi je lui dis pas en turc, ou en portugais, ou en, j'sais pas moi en arabe": exploring teacher ideologies in multilingual/cultural preschool contexts in France
This contribution explores the relationship between language ideologies and teaching with specific reference to the French national education context and in particular with respect to the education of children for whom French, the language of schooling, is not the language spoken in the home. The discourse of three teachers working in multilingual/cultural preschools is examined, revealing both beliefs about languages and practiced language policies underpinned by deep-rooted language ideologies which perpetuate a monolingual habitus. It is argued that in order to challenge the myths which support this monolingual mindset, it is essential to nurture teacher language awareness, underpinned by knowledge, values and a deeper understanding of the complexities of living and learning through multiple languages.Este artículo explora la relación entre ideologías lingüísticas y prácticas educativas de los maestros de preescolar en Francia, en particular maestros que trabajan con alumnos que hablan una lengua diferent que la lengua vehicular de la escuela. El análisis de discurso de tres profesores que trabajan en contextos lingüística y culturalmente heterogéneos revela que sus representaciones y sus políticas lingüísticas practicadas, son arraigadas en ideologías que perpetúan el habitus monolingüe. Con el fin de desafiar los mitos subyacentes a esta visión monolingüe del aprendizaje y de la enseñanza, hay que desarrollar la conciencia lingüística, alimentada por los conocimientos, valores y comprensión de las complejidades asociadas con el aprendizaje y la enseñanza de idiomas multilingüe.Aquest article explora la relació entre ideologies lingüístiques i pràctiques educatives dels mestres de preescolar a França, en particular mestres qui treballen amb alumnes per als que la llengua de l'escola no és l'idioma que parlen a casa. Anàlisi de discurs de tres professors que treballen en contextos lingüística i culturalment heterogenis revela que les seves representacions i les seves polítiques lingüístiques practicades, són arrelades en ideologies que perpetuen l'habitus monolingüe. Per tal de desafiar els mites subjacents a aquesta visió monolingüe d'aprenentatge i ensenyament, cal desenvolupar la consciència lingüística, alimentada pels coneixements, valors i comprensió de les complexitats associades amb l'aprenentatge i l'ensenyament d'idiomes multilingüe.Cette contribution explore la relation entre les idéologies linguistiques et les pratiques pédagogiques d'enseignants d'école maternelle en France envers les élèves pour qui la langue de l'école n'est pas la langue parlée à la maison. L'analyse de discours de trois enseignantes qui travaillent dans des contextes linguistiquement et culturellement hétérogènes, révèle des représentations ainsi que des politiques linguistiques pratiquées, ancrées dans des idéologies qui font perdurer l'habitus monolingue. Dans l'optique de remettre en question les mythes qui sous-tendent cette vision monolingue de l'apprentissage et de l'enseignement, le développement d'une conscience linguistique, nourrie par des connaissances, des valeurs et une meilleure compréhension des complexités associées à l'apprentissage et à l'enseignement en milieu multilingue, est proposé
Inhibition of vascular endothelial growth factor‐A downregulates angiogenesis in psoriasis: A pilot study
BackgroundVascular Endothelial Growth Factor (VEGF)-A-mediated angiogenesis participates in the pathogenesis of psoriasis, thus inviting the hypothesis that anti-VEGF-A therapy could be beneficial in psoriasis. While anti-angiogenic agents are used in oncology and ophthalmology, these therapeutic strategies remain unexplored for the management of psoriasis.ObjectiveOur objective was to investigate ex vivo how VEGF-A blockade impacts blood vessels, epidermis and immune cells in organ-cultured plaque and non-lesional skin from patients with psoriasis.MethodsSkin biopsies from patients with psoriasis (n = 6; plaque and non-lesional skin) and healthy controls (n = 6) were incubated with anti-VEGF-A monoclonal antibody (bevacizumab, Avastin®) or a human IgG1 isotype control for 72-h in serum-free organ culture. CD31/LYVE-1, Ki-67, and mast cell tryptase expression were assessed by quantitative immunohistomorphometry. VEGF-A levels in plasma, PBMCs and skin culture supernatants were measured.ResultsInhibition of VEGF-A blocked all free VEGF-A ex vivo, reduced blood vessel area and the number of blood vessel endothelial cells in plaques of psoriasis (*p < 0.05). The treatment effect correlated significantly with levels of VEGF-A in organ culture supernatants (r = 0.94; *p < 0.05) from plaque skin and with plasma levels of VEGF-A from patients with psoriasis (r = 0.943; *p = 0.017).ConclusionsThese ex vivo data are the first studies to objectively investigate the potential of VEGF-A inhibition as a novel adjuvant treatment strategy for psoriasis. Taken together, our data encourage further investigation by clinical trial to explore whether downregulating pathological angiogenesis has clinical utility, especially in patients with severe psoriasis or those with elevated levels of VEGF-A in plasma and/or skin
UV Spectropolarimetry of Narrow-line Radio Galaxies
We present the results of UV spectropolarimetry (2000 - 3000A) and far-UV
spectroscopy (1500 - 2000A) of two low-redshift narrow-line radio galaxies
(NLRGs) taken with the Faint Object Spectrograph onboard the Hubble Space
Telescope (HST). Spectropolarimetry of several NLRGs has shown that, by the
presence of broad permitted lines in polarized flux spectrum, they have hidden
quasars seen through scattered light. Imaging polarimetry has shown that NLRGs
including our targets often have large scattering regions of a few kpc to >~10
kpc scale. This has posed a problem about the nature of the scatterers in these
radio galaxies. Their polarized continuum has the spectral index similar to or
no bluer than that of quasars, which favors electrons as the dominant
scattering particles. The large scattering region size, however, favors dust
scattering, because of its higher scattering efficiency compared to electrons.
In this paper, we investigate the polarized flux spectrum over a wide
wavelength range, combining our UV data with previous optical/infrared
polarimetry data. We infer that the scattering would be often caused by opaque
dust clouds in the NLRGs and this would be a part of the reason for the
apparently grey scattering. In the high-redshift radio galaxies, these opaque
clouds could be the proto-galactic subunits inferred to be seen in the HST
images. However, we still cannot rule out the possibility of electron
scattering, which could imply the existence of a large gas mass surrounding
these radio galaxies.Comment: 25 pages, 21 figures. To appear in Ap
Nanofilters for Optical Nanocircuits
We theoretically and numerically study the design of optical 'lumped'
nanofiltering devices in the framework of our recently proposed paradigm for
optical nanocircuits. In particular, we present the design of basic filtering
elements, such as low-pass, band-pass, stop-band and high-pass 'lumped'
nanofilters, for use in optical nanocircuits together with more complex
designs, such as multi-zero or multi-pole nanofilters, to work at THz, infrared
and optical frequencies. Following the nanocircuit theory, we show how it is
possible to design such complex frequency responses by simple rules, similar to
RF circuit design, and we compare the frequency response of these optical
nanofilters with classic filters in RF circuits. These results may provide a
theoretical foundation for fabricating nanofilters in optical lumped
nanocircuit devices.Comment: 34 pages, 14 figure
Synthesis and Characterization of Single Crystal Samples of Spin- Kagome Lattice Antiferromagnets in the Zn-Paratacamite Family ZnCu(OH)Cl
The Zn-paratacamite family, ZnCu(OH)Cl for 0.33, is an ideal system for studying spin-1/2 frustrated magnetism in
the form of antiferromagnetic Cu kagome planes. Here we report a new
synthesis method by which high quality millimeter-sized single crystals of
Zn-paratacamite have been produced. These crystals have been characterized by
metal analysis, x-ray diffraction, neutron diffraction, and thermodynamic
measurements. The = 1 member of the series displays a magnetic
susceptibility that is slightly anisotropic at high temperatures with . Neutron and synchrotron x-ray diffraction experiments
confirm the quality of these = 1 single crystals and indicate no obvious
structural transition down to temperatures of T=2 K.Comment: 4 pages, 3 figures, accepted by PRB rapid communicatio
Association between 5-HTTLPR and Borderline Personality Disorder Traits among Youth
This study provides the first genetic association examination of borderline personality disorder (BPD) traits in children and adolescents (ages 9–15) using two independent samples of youth recruited from the general community. We tested the a priori hypothesis that the serotonin transporter promoter gene (5-HTTLPR) would relate specifically to BPD traits in youth. This association was hypothesized based on prior genetic association research with BPD adults and theory positing that emotion dysregulation may be a core risk process contributing to BPD. Youth provided DNA via buccal cells. Both youth and a parent completed self-report measures assessing youth's BPD traits and depressive symptoms. Results from both Study 1 (N = 242) and an independent replication sample of Study 2 (N = 144) showed that carriers of the short allele of 5-HTTLPR exhibited the highest levels of BPD traits. This relation was observed even after controlling for the substantial co-occurrence between BPD traits and depressive symptoms. This specific association between 5-HTTLPR and BPD traits among youth supports previous genetic associations with adults diagnosed with BPD and provides preliminary support for a developmental extension of etiological risk for BPD among youth
Quantum interference and Klein tunneling in graphene heterojunctions
The observation of quantum conductance oscillations in mesoscopic systems has
traditionally required the confinement of the carriers to a phase space of
reduced dimensionality. While electron optics such as lensing and focusing have
been demonstrated experimentally, building a collimated electron interferometer
in two unconfined dimensions has remained a challenge due to the difficulty of
creating electrostatic barriers that are sharp on the order of the electron
wavelength. Here, we report the observation of conductance oscillations in
extremely narrow graphene heterostructures where a resonant cavity is formed
between two electrostatically created bipolar junctions. Analysis of the
oscillations confirms that p-n junctions have a collimating effect on
ballistically transmitted carriers. The phase shift observed in the conductance
fringes at low magnetic fields is a signature of the perfect transmission of
carriers normally incident on the junctions and thus constitutes a direct
experimental observation of ``Klein Tunneling.''Comment: 13 pages and 6 figures including supplementary information. The paper
has been modified in light of new theoretical results available at
arXiv:0808.048
Absence of a Finite-Temperature Melting Transition in the Classical Two-Dimensional One-Component Plasma
Vortices in thin-film superconductors are often modelled as a system of
particles interacting via a repulsive logarithmic potential. Arguments are
presented to show that the hypothetical (Abrikosov) crystalline state for such
particles is unstable at any finite temperature against proliferation of
screened disclinations. The correlation length of crystalline order is
predicted to grow as as the temperature is reduced to zero, in
excellent agreement with our simulations of this two-dimensional system.Comment: 3 figure
Disentangling protostellar evolutionary stages in clustered environments using Spitzer-IRS spectra and comprehensive SED modeling
When studying the evolutionary stages of protostars that form in clusters,
the role of any intracluster medium cannot be neglected. High foreground
extinction can lead to situations where young stellar objects (YSOs) appear to
be in earlier evolutionary stages than they actually are, particularly when
using simple criteria like spectral indices. To address this issue, we have
assembled detailed SED characterizations of a sample of 56 Spitzer-identified
candidate YSOs in the clusters NGC 2264 and IC 348. For these, we use spectra
obtained with the Infrared Spectrograph onboard the Spitzer Space Telescope and
ancillary multi-wavelength photometry. The primary aim is twofold: 1) to
discuss the role of spectral features, particularly those due to ices and
silicates, in determining a YSO's evolutionary stage, and 2) to perform
comprehensive modeling of spectral energy distributions (SEDs) enhanced by the
IRS data. The SEDs consist of ancillary optical-to-submillimeter
multi-wavelength data as well as an accurate description of the 9.7 micron
silicate feature and of the mid-infrared continuum derived from line-free parts
of the IRS spectra. We find that using this approach, we can distinguish
genuine protostars in the cluster from T Tauri stars masquerading as protostars
due to external foreground extinction. Our results underline the importance of
photometric data in the far-infrared/submillimeter wavelength range, at
sufficiently high angular resolution to more accurately classify cluster
members. Such observations are becoming possible now with the advent of the
Herschel Space Observatory.Comment: Accepted for publication in Ap
Critical behavior of the random-anisotropy model in the strong-anisotropy limit
We investigate the nature of the critical behavior of the random-anisotropy
Heisenberg model (RAM), which describes a magnetic system with random uniaxial
single-site anisotropy, such as some amorphous alloys of rare earths and
transition metals. In particular, we consider the strong-anisotropy limit
(SRAM), in which the Hamiltonian can be rewritten as the one of an Ising
spin-glass model with correlated bond disorder. We perform Monte Carlo
simulations of the SRAM on simple cubic L^3 lattices, up to L=30, measuring
correlation functions of the replica-replica overlap, which is the order
parameter at a glass transition. The corresponding results show critical
behavior and finite-size scaling. They provide evidence of a finite-temperature
continuous transition with critical exponents and
. These results are close to the corresponding estimates that
have been obtained in the usual Ising spin-glass model with uncorrelated bond
disorder, suggesting that the two models belong to the same universality class.
We also determine the leading correction-to-scaling exponent finding .Comment: 24 pages, 13 figs, J. Stat. Mech. in pres
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