1,049 research outputs found
Magnetism of two-dimensional defects in Pd: stacking faults, twin boundaries and surfaces
Careful first-principles density functional calculations reveal the
importance of hexagonal versus cubic stacking of closed packed planes of Pd as
far as local magnetic properties are concerned. We find that, contrary to the
stable face centered cubic phase, which is paramagnetic, the hexagonal
close-packed phase of Pd is ferromagnetic with a magnetic moment of 0.35
/atom. Our results show that two-dimensional defects with local hcp
stacking, like twin boundaries and stacking faults, in the otherwise fcc Pd
structure, increase the magnetic susceptibility. The (111) surface also
increases the magnetic susceptibility and it becomes ferromagnetic in
combination with an individual stacking fault or twin boundary close to it. On
the contrary, we find that the (100) surface decreases the tendency to
ferromagnetism. The results are consistent with the magnetic moment recently
observed in small Pd nanoparticles, with a large surface area and a high
concentration of two-dimensional stacking defects.Comment: 8 pages, 10 figure
L’influence de la variable niveau socioculturel dans les formes d’adresse
En el presente artÃculo se
muestran los resultados obtenidos en un
estudio sobre la incidencia de la variable
nivel sociocultural en la elección de las formas
de tratamiento tú y usted en el español
peninsular actual. Para llevarlo a cabo,
en primer lugar se han estudiado las principales
caracterÃsticas de esta compleja variable
sociolingüÃstica y, a continuación,
se ha realizado una encuesta a una muestra
de un total de 190 estudiantes con edades
comprendidas entre los 18 y los 25
años residentes en la ciudad de Salamanca.
Para ello, se ha creado una encuesta
ad hoc que contiene distintas situaciones
comunicativas en las que se combinan
variables sociales y contextuales, de
acuerdo con la bibliografÃa especializada.
Los resultados se han procesado estadÃsticamente
y permiten observar el importante
papel que desempeña en la elección pronominal
el nivel sociocultural del interlocutor
y también –aunque en menor medida– el
del propio hablante.This article shows the
results obtained in a study about the
incidence of the social class variables
when choosing between the address
forms tú and usted in current peninsular
Spanish. In order to carry this
study out, the main characteristics of
this variable have been primarily
studied, and secondly, a survey was
given to a sample of 190 students
with ages between 18 and 25 years
old who reside in the city of Salamanca
(Spain). To do that, an ad hoc
survey has been created, containing
different communicative situations
that combine social and contextual
variables, according to the specialized
bibliography. The results have
been statistically processed and allow
us to observe the important role
that social class variables of the interlocutor,
but also –to a lesser extent–
of the speaker, take when
choosing one of the pronouns.Cet article présente les résultats
obtenus au cours d’une étude sur
l’incidence de la variable du niveau socioculturel
dans l’élection des formes
d’adresse tú et usted en espagnol péninsulaire
actuel. Pour réaliser l’étude,
nous avons présenté les caractéristiques
principales de cette complexe variable
sociolinguistique et, ensuite,
nous avons effectué une enquête sur un
total de 190 étudiants d’entre 18 et 25
ans qui résident à Salamanque (Espagne).
Pour ce faire, nous avons créé
une enquête ad hoc qui contient différentes
situations communicatives dans
lesquelles sont combinées variables sociales
et contextuelles, conformément Ã
la bibliographie spécialisée. Les résultats
ont été traités statistiquement et
permettent d’observer l’importance du
rôle du niveau socioculturel de l’interlocuteur
et du locuteur –à une moindre
échelle– dans l’élection pronominale
Lung tumorspheres as a drug screening platform against cancer stem cells
Treatment resistance and metastasis are linked to cancer stem cells (CSCs). This population represents a promising target, but remains unexplored in lung cancer. The main objective of this study was to characterize lung CSCs and discover new therapeutic strategies
Variación en la cortesÃa en la expresión de la petición en el español castellano y el portugués europeo
In this article we present the results of a contrastive analysis about the politeness strategies used in the expression of petitions in Castilian Spanish and European Portuguese. By using the DCT methodology, we have designed a questionnaire with petitions of different cost-benefit for the conversational partner and with variations relative to power and the social distance that exists between the participants. Once the data was gathered, we did a triple study about the differences in the expression of petitions: 1) between Spanish and Portuguese, 2) from the rank of imposition of the object and the petition, and 3) according to the social distance and the relative power of the participants. The results show that, although using different linguistic and politeness strategies, the expression of petitions is similar between Spanish and Portuguese speakers, although the latter take the social distance and the relative power of the hearer more into account than the Spanish speakers at the moment of choosing politeness forms.En este artÃculo se presentan los resultados de un análisis contrastivo de las estrategias de cortesÃa empleadas en la expresión de la petición en el español castellano y en el portugués europeo. A través de la metodologÃa DCT, se ha diseñado un cuestionario con peticiones con distinto coste-beneficio para el interlocutor y con variaciones relativas al poder y a la distancia social existente entre los participantes. Una vez recopilados los datos, se ha realizado un triple estudio sobre las diferencias en la formulación de las peticiones: 1) entre el español y el portugués, 2) a partir del grado de imposición del objeto de la petición y 3) según la distancia social y el poder relativo de los interlocutores. Los resultados muestran que, a pesar de utilizar estrategias diferenciadas, la expresión de la petición es similar entre los hablantes de español y de portugués, si bien estos últimos tienen más en cuenta que los hispanohablantes la distancia social y el poder relativo del receptor en la elección de las formas de cortesÃa
MS-EMC vs. NEGF: A comparative study accounting for transport quantum corrections
As electronic devices approach the nanometer scale, quantum transport theories have been recognized as the best option to reproduce their performance. Other possible trend, mainly focused on reducing the computational effort, is the inclusion of quantum effects in semi-classical simulators. This work presents a comparison between a NEGF simulator and a MS-EMC tool including S/D tunneling both applied on a DGSOI transistor
Progressive myoclonus epilepsy KCNC1 variant causes a developmental dendritopathy
OBJECTIVE: Mutations in KCNC1 can cause severe neurological dysfunction, including intellectual disability, epilepsy, and ataxia. The Arg320His variant, which occurs in the voltage-sensing domain of the channel, causes a highly penetrant and specific form of progressive myoclonus epilepsy with severe ataxia, designated myoclonus epilepsy and ataxia due to potassium channel mutation (MEAK). KCNC1 encodes the voltage-gated potassium channel KV 3.1, a channel that is important for enabling high-frequency firing in interneurons, raising the possibility that MEAK is associated with reduced interneuronal function. METHODS: To determine how this variant triggers MEAK, we expressed KV 3.1bR320H in cortical interneurons in vitro and investigated the effects on neuronal function and morphology. We also performed electrophysiological recordings of oocytes expressing KV 3.1b to determine whether the mutation introduces gating pore currents. RESULTS: Expression of the KV 3.1bR320H variant profoundly reduced excitability of mature cortical interneurons, and cells expressing these channels were unable to support high-frequency firing. The mutant channel also had an unexpected effect on morphology, severely impairing neurite development and interneuron viability, an effect that could not be rescued by blocking KV 3 channels. Oocyte recordings confirmed that in the adult KV 3.1b isoform, R320H confers a dominant negative loss-of-function effect by slowing channel activation, but does not introduce potentially toxic gating pore currents. SIGNIFICANCE: Overall, our data suggest that, in addition to the regulation of high-frequency firing, KV 3.1 channels play a hitherto unrecognized role in neuronal development. MEAK may be described as a developmental dendritopathy
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