1,302 research outputs found
Anderson impurity model in nonequilibrium: analytical results versus quantum Monte Carlo data
We analyze the spectral function of the single-impurity two-terminal Anderson
model at finite voltage using the recently developed diagrammatic quantum Monte
Carlo technique as well as perturbation theory. In the
(particle-hole-)symmetric case we find an excellent agreement of the numerical
data with the perturbative results of second order up to interaction strengths
, where is the transparency of the
impurity-electrode interface. The analytical results are obtained in form of
the nonequilibrium self-energy for which we present explicit formulas in the
closed form at arbitrary bias voltage. We observe an increase of the spectral
density around zero energy brought about by the Kondo effect. Our analysis
suggests that a finite applied voltage acts as an effective temperature of
the system. We conclude that at voltages significantly larger than the
equilibrium Kondo temperature there is a complete suppression of the Kondo
effect and no resonance splitting can be observed. We confirm this scenario by
comparison of the numerical data with the perturbative results.Comment: 8 pages, 6 figure
A Minimum-Labeling Approach for Reconstructing Protein Networks across Multiple Conditions
The sheer amounts of biological data that are generated in recent years have
driven the development of network analysis tools to facilitate the
interpretation and representation of these data. A fundamental challenge in
this domain is the reconstruction of a protein-protein subnetwork that
underlies a process of interest from a genome-wide screen of associated genes.
Despite intense work in this area, current algorithmic approaches are largely
limited to analyzing a single screen and are, thus, unable to account for
information on condition-specific genes, or reveal the dynamics (over time or
condition) of the process in question. Here we propose a novel formulation for
network reconstruction from multiple-condition data and devise an efficient
integer program solution for it. We apply our algorithm to analyze the response
to influenza infection in humans over time as well as to analyze a pair of ER
export related screens in humans. By comparing to an extant, single-condition
tool we demonstrate the power of our new approach in integrating data from
multiple conditions in a compact and coherent manner, capturing the dynamics of
the underlying processes.Comment: Peer-reviewed and presented as part of the 13th Workshop on
Algorithms in Bioinformatics (WABI2013
Tcnq-based Porous Coordination Polymers Synthesis and Sorption Properties Study in Magnetic Field
Porous coordination polymers (PCPs) were synthesized with used TCNQ anion that acts as cross linker connecting and bipyridine to form a 3D framework. In these study, we use zinc and manganese metal ion as centre of complex coordination. Green crystal of Zn(TCNQ-TCNQ)bpy.1.5 benzene and Mn(TCNQ-TCNQ)bpy.1.5 benzene was successfully synthesized in no under magnetic field (0T) and under magnetic field 6T. XRD patterns of Zn(TCNQ-TCNQ)bpy.1.5 benzene 0T and 6T shown not significant different pattern that indicate no different crytal formed. XRD patterns of Mn(TCNQ-TCNQ)bpy.1.5 benzene also shown not significant different but we found five different intensity ratio peaks that possibility it was a little bit changing of crystal structure. To investigate the pores properties, adsorption isotherm was performe for oxygen gas in 77 K and the guest of benzene were removed at 413 K for 3 hours under low pressure. Zn(TCNQ-TCNQ)bpy}1.5benzene 0T and 6T oxygen adsorption isotherms shows the unique sorption isotherms by gate pressure profile. On other hand, Mn(TCNQ-TCNQ)bpy}1.5 benzene 0T and 6T shows type 1 adsorption isotherms for micropores materials. Adsorption isotherm was also determined in magnetic field 6T for all crystal, and shows shift of gate pressure for Zn compounds and enhance the amount of oxygen adsorbed for all kind of compounds
EMX2 regulates sizes and positioning of the primary sensory and motor areas in neocortex by direct specification of cortical progenitors
Genetic studies of neocortical area patterning are limited, because mice deficient for candidate regulatory genes die before areas emerge and have other compli-cating issues. To define roles for the homeodomain transcription factor EMX2, we engineered nestin-Emx2 transgenic mice that overexpress Emx2 in cortical pro-genitors coincident with expression of endogenous Emx2 and survive postnatally. Cortical size, lamina-tion, thalamus, and thalamocortical pathfinding are normal in homozygous nestin-Emx2 mice. However, primary sensory and motor areas are disproportion-ately altered in size and shift rostrolaterally. Heterozygous transgenics have similar but smaller changes. Opposite changes are found in heterozygous Emx2 knockout mice. Fgf8 expression in the commissural plate of nestin-Emx2 mice is indistinguishable from wild-type, but Pax6 expression is downregulated in rostral cortical progenitors, suggesting that EMX2 re-pression of PAX6 specification of rostral identities contributes to reduced rostral areas. We conclude that EMX2 levels in cortical progenitors disproportionately specify sizes and positions of primary cortical areas
Magnetic and electric properties in the distorted tetrahedral spin chain system Cu3Mo2O9
We study the multiferroic properties in the distorted tetrahedral quasi-one
dimensional spin system CuMoO, in which the effects of the low
dimensionality and the magnetic frustration are expected to appear
simultaneously. We clarify that the antiferromagnetic order is formed together
with ferroelectric properties at K under zero magnetic field
and obtain the magnetic-field-temperature phase diagram by measuring dielectric
constant and spontaneous electric polarization. It is found that the
antiferromagnetic phase possesses a spontaneous electric polarization parallel
to the c axis when the magnetic field is applied parallel to the a axis. On
the other hand, there are three different ferroelectric phases in the
antiferromagnetic phase for parallel to the c axis.Comment: 4 pages, 3 figures, LT26 proceedings, accepted for publication in J.
Phys.: Conf. Se
Cerâmica: interação e produção de sentido na educação a distância.
Esta pesquisa objetiva observar as interações entre os alunos, professores e tutores presentes no Ambiente Virtual de Aprendizagem, objetivando uma compreensão do contexto analisado e das atitudes e interações no processo de ensino e aprendizagem que ocorre nesse ambiente virtual. Para a análise, foram selecionados os fóruns (Fórum Construir Saberes, Fórum Tira Dúvidas e Fórum de Tutores) da disciplina Cerâmica, do Curso de Artes Visuais Licenciatura, modalidade semipresencial, da Universidade Federal do EspÃrito Santo (Ufes). Como o curso foi ofertado para 22 polos de formação, elegeram-se para análise as postagens dos alunos de Aracruz e Santa Teresa. A metodologia utilizada foi a etnografia virtual, por abranger estudos no/do ciberespaço e no/do ambiente virtual. Como referencial analÃtico, foram utilizados os pressupostos da sociossemiótica, especialmente com base no pesquisador Eric Landowski (1992, 2001, 2002, 2005) por possibilitar a apreensão dos sentidos presentes nos discursos e nas práticas educativas do/no ambiente virtual. No ambiente virtual, a construção do conhecimento ocorre, num primeiro momento, sem a necessidade da relação presencial entre o professor e o aluno, e as narrativas tornam-se instrumentos de mediação na construção desse conhecimento. Nesse ambiente, as relações são estabelecidas a partir da constituição de diferentes tipos de papéis e identidades. É por meio dessa interação, mediada pelo Ambiente Virtual de Aprendizagem (AVA), que os sujeitos envolvidos constroem suas ações e seus atos a partir de cada deslocamento e participação nesse ambiente virtual, remodelando e redefinindo suas práticas. Landowski (2009) afirma que nossas relações são carregadas de sentido, de emoções que brotam da nossa experiência cotidiana, invalidando qualquer forma de objetividade e regularidade previsÃvel, pois se trata do sentido. É esse sentido que esta pesquisa pretende revelar, por meio dos regimes da semiótica discursiva
Superconducting non-equilibrium transport through a weakly interacting quantum dot
We study the out-of-equilibrium current through an interacting quantum dot
modelled as an Anderson impurity contacted by two BCS superconductors held at
fixed voltage bias. In order to account for multiple Andreev reflections, we
develop a Keldysh Green's function scheme perturbative in the dot's interaction
strength. We find an unexpected enhancement of the current due to repulsive
interactions for small lead-to-dot couplings.Comment: 6 pages, 6 figures, replaced with published versio
Electric polarization induced by Neel order without magnetic superlattice: experimental study of Cu3Mo2O9 and numerical study of a small spin cluster
We clarify that the antiferromagnetic order in the distorted tetrahedral
quasi-one dimensional spin system induces electric polarizations. In this
system, the effects of the low dimensionality and the magnetic frustration are
expected to appear simultaneously. We obtain the magnetic-field-temperature
phase diagram in Cu3Mo2O9 by studying the dielectric constant and the
spontaneous electric polarization. Around the tricritical point at 10 T and 8
K, the change of the direction in the electric polarization causes a colossal
magnetocapacitance. We calculate the charge redistribution in the small spin
cluster consisting of two magnetic tetrahedra to demonstrate the electric
polarization induced by the antiferromagnetism.Comment: 10 pages 6 figures, in press in J. Phys. Soc. Jp
ARSENIC REMOVAL FROM GROUNDWATER USING INDIGENOUS IRON AND MANGANESE OXDIZING BACTERIA
Joint Research on Environmental Science and Technology for the Eart
Coronary lumen at six-month follow-up of a new radiopaque Cordis tantalum stent using quantitative angiography and intracoronary ultrasound.
To determine the reliability of geometric (edge-detection) quantitative coronary angiographic analysis (QCA) of restenosis within a new Cordis tantalum stent, QCA and intracoronary ultrasound (ICUS) measurements were compared in both an experimental restenosis model and in the clinical follow-up of patients. In the experimental series, Plexiglas phantom vessels with concentric stenosis channels ranging from 0.75 to 3.0 mm in diameter and with a reference diameter of 3.0 mm were imaged both before and after their insertion in tantalum stents. In the clinical series, the agreement of QCA and ICUS measurements were studied in 23 patients who had undergone coronary implantation of the new tantalum stent and in 23 patients who had undergone balloon angioplasty 6 months previously. The reliability of QCA declined in the presence of the radiopaque stent (accuracy of QCA decreased from -0.07 to -0.12 mm), whereas the reliability of lumen measurements by ICUS was independent of the presence of the radiopaque stent (-0.12 and -0.13 mm). Without the stent, the average minimal luminal diameter (MLD) obtained by QCA of the 1.00 mm Plexiglas vessel was 1.00 +/- 0.01 mm, and the 3.00 mm reference vessel diameter was 2.81 +/- 0.05 mm, providing a 64 +/- 1% diameter stenosis. After introduction of the stent, the average MLD and reference vessel diameter were 0.99 +/- 0.06 and 3.36 +/- 0.17 mm, respectively, providing a diameter stenosis of 71 +/- 2%. ICUS measurements (2.77 mm) of the reference vessel diameter (3.00 mm) were unaffected by the presence of the stent. (ABSTRACT TRUNCATED AT 250 WORDS
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