8,676 research outputs found
Interaction energy functional for lattice density functional theory: Applications to one-, two- and three-dimensional Hubbard models
The Hubbard model is investigated in the framework of lattice density
functional theory (LDFT). The single-particle density matrix with
respect the lattice sites is considered as the basic variable of the many-body
problem. A new approximation to the interaction-energy functional
is proposed which is based on its scaling properties and which recovers exactly
the limit of strong electron correlations at half-band filling. In this way, a
more accurate description of is obtained throughout the domain of
representability of , including the crossover from weak to strong
correlations. As examples of applications results are given for the
ground-state energy, charge-excitation gap, and charge susceptibility of the
Hubbard model in one-, two-, and three-dimensional lattices. The performance of
the method is demonstrated by comparison with available exact solutions, with
numerical calculations, and with LDFT using a simpler dimer ansatz for .
Goals and limitations of the different approximations are discussed.Comment: 25 pages and 8 figures, submitted to Phys. Rev.
¿Es Husserl un disyuntivista? La fenomenología ante un problema contemporáneo de la filosofía de la percepción
Under the framework of static phenomenology, I will introduce the Husserlian descriptions of the relation between sensible content and apprehension (Inhalt-Auffassungsschema), and the non-representationalist approach to perception of transcendental phenomenology. In order to place Husserlian phenomenology in a context marked by disjunctivism, I will confront some objections that emerged from certain readings of the transcendental method. Finally, I will reject the tightness of the debate between disjunctivists and representationalists, giving way to the possibilities opened by phenomenology in the description of perception
La tradition allemande dans la philosophie, de Alain Badiou y Jean-Luc Nancy
Reseña en español del diálogo entre A. Badiou y J.-L. Nancy, editado por Jan Völker y publicado en 2017
La primacía de la percepción en la teoría husserliana temprana de la imaginación
Este artículo está enfocado en la primera etapa de las investigaciones husserlianas sobre la imaginación, enmarcadas en su obra “estática” y determinadas, especialmente, por las características de una concepción centrada en la imagen figurativa (Abbild)
Norovirus Infection and Disease in an Ecuadorian Birth Cohort: Association of Certain Norovirus Genotypes With Host FUT2 Secretor Status.
BACKGROUND: Although norovirus is the most common cause of gastroenteritis, there are few data on the community incidence of infection/disease or the patterns of acquired immunity or innate resistance to norovirus. METHODS: We followed a community-based birth cohort of 194 children in Ecuador with the aim to estimate (1) the incidence of norovirus gastroenteritis from birth to age 3 years, (2) the protective effect of norovirus infection against subsequent infection/disease, and (3) the association of infection and disease with FUT2 secretor status. RESULTS: Over the 3-year period, we detected a mean of 2.26 diarrheal episodes per child (range, 0-12 episodes). Norovirus was detected in 260 samples (18%) but was not found more frequently in diarrheal samples (79 of 438 [18%]), compared with diarrhea-free samples (181 of 1016 [18%]; P = .919). A total of 66% of children had at least 1 norovirus infection during the first 3 years of life, and 40% of children had 2 infections. Previous norovirus infections were not associated with the risk of subsequent infection. All genogroup II, genotype 4 (GII.4) infections were among secretor-positive children (P < .001), but higher rates of non-GII.4 infections were found in secretor-negative children (relative risk, 0.56; P = .029). CONCLUSIONS: GII.4 infections were uniquely detected in secretor-positive children, while non-GII.4 infections were more often found in secretor-negative children
Semblanzas de los toreros del día
Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2012-201
Construcción de una memoria organizacional a partir de textos no estructurados usando herramientas de minería de texto
Trabajo que tuvo como propósito construir una memoria organizacional de los Reportes de Proyectos de Aplicación Profesional (PAP) a partir de texto no estructurado usando herramientas de minería de texto. El objetivo fue brindar una herramienta a la Coordinación PAP para obtener estadísticas, información de interés, aprendizajes y experiencias plasmadas por los alumnos en sus reportes que ayuden a generar nuevo proyectos, mejorar existentes, facilitar la toma de decisiones, así como llevar un registro de las vinculaciones entre instituciones públicas y/o privadas y el ITESO.Consejo Nacional de Ciencia y Tecnologí
El sector pecuario y la tecnificación fiscal. Las tribulaciones de un productor
El propósito de este artículo es reflexionar y presentar evidencias de primera mano sobre las complicaciones, costos e irregularidades que los productores del sector primario enfrentan ante la disposición hacendaria (a través del Servicio de Administración Tributaria, SAT) de emitir comprobante fiscal digital (CFDI) al vender productos del campo.ITESO, A.C
Extreme Quiescent Variability of the Transient Neutron Star Low-mass X-ray Binary EXO 1745-248 in Terzan 5
EXO 1745-248 is a transient neutron-star low-mass X-ray binary that resides
in the globular cluster Terzan 5. We studied the transient during its quiescent
state using 18 Chandra observations of the cluster acquired between 2003 and
2016. We found an extremely variable source, with a luminosity variation in the
0.5-10 keV energy range of orders of magnitude (between
erg s and erg s) on timescales
from years down to only a few days. Using an absorbed power-law model to fit
its quiescent spectra, we obtained a typical photon index of ,
indicating that the source is even harder than during outburst and much harder
than typical quiescent neutron stars if their quiescent X-ray spectra are also
described by a single power-law model. This indicates that EXO 1745-248 is very
hard throughout the entire observed X-ray luminosity range. At the highest
luminosity, the spectrum fits better when an additional (soft) component is
added to the model. All these quiescent properties are likely related to strong
variability in the low-level accretion rate in the system. However, its extreme
variable behavior is strikingly different from the one observed for other
neutron star transients that are thought to still accrete in quiescence. We
compare our results to these systems. We also discuss similarities and
differences between our target and the transitional millisecond pulsar IGR
J18245-2452, which also has hard spectra and strong variability during
quiescence.Comment: Accepted for publication in MNRA
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