6,141 research outputs found
Supermanifolds, symplectic geometry and curvature
We present a survey of some results and questions related to the notion of
scalar curvature in the setting of symplectic supermanifolds.Comment: Dedicated to Jaime Mu\~noz-Masqu\'e on occasion of his 65th birthda
Structural phase transition in IrTe: A combined study of optical spectroscopy and band structure calculations
IrPtTe is an interesting system showing competing phenomenon
between structural instability and superconductivity. Due to the large atomic
numbers of Ir and Te, the spin-orbital coupling is expected to be strong in the
system which may lead to nonconventional superconductivity. We grew single
crystal samples of this system and investigated their electronic properties. In
particular, we performed optical spectroscopic measurements, in combination
with density function calculations, on the undoped compound IrTe in an
effort to elucidate the origin of the structural phase transition at 280 K. The
measurement revealed a dramatic reconstruction of band structure and a
significant reduction of conducting carriers below the phase transition. We
elaborate that the transition is not driven by the density wave type
instability but caused by the crystal field effect which further
splits/separates the energy levels of Te (p, p) and Te p bands.Comment: 16 pages, 5 figure
Improved maximum likelihood estimators in a heteroskedastic errors-in-variables model
This paper develops a bias correction scheme for a multivariate
heteroskedastic errors-in-variables model. The applicability of this model is
justified in areas such as astrophysics, epidemiology and analytical chemistry,
where the variables are subject to measurement errors and the variances vary
with the observations. We conduct Monte Carlo simulations to investigate the
performance of the corrected estimators. The numerical results show that the
bias correction scheme yields nearly unbiased estimates. We also give an
application to a real data set.Comment: 12 pages. Statistical Paper
Diffusion microscopic MRI of the mouse embryo: Protocol and practical implementation in the splotch mouse model
Advanced methodologies for visualizing novel tissue contrast are essential for phenotyping the ever-increasing number of mutant mouse embryos being generated. Although diffusion microscopic MRI (μMRI) has been used to phenotype embryos, widespread routine use is limited by extended scanning times, and there is no established experimental procedure ensuring optimal data acquisition
TBA for non-perturbative moduli spaces
Recently, an exact description of instanton corrections to the moduli spaces
of 4d N=2 supersymmetric gauge theories compactified on a circle and Calabi-Yau
compactifications of Type II superstring theories was found. The equations
determining the instanton contributions turn out to have the form of
Thermodynamic Bethe Ansatz. We explore further this relation and, in
particular, we identify the contact potential of quaternionic string moduli
space with the free energy of the integrable system and the Kahler potential of
the gauge theory moduli space with the Yang-Yang functional. We also show that
the corresponding S-matrix satisfies all usual constraints of 2d integrable
models, including crossing and bootstrap, and derive the associated Y-system.
Surprisingly, in the simplest case the Y-system is described by the MacMahon
function relevant for crystal melting and topological strings.Comment: 25 pages, 1 figur
Use of five probiotic strains to determine sensitivity in vitro on pathogenic bacteria growth isolated from sick fishes
ABSTRACT Ornamental aquaculture is an activity in clear economic growth, both globally and in Mexico where the development is particularly relevant to freshwater species. Infectious diseases produced by fungus, bacteria and virus are considered one of the principal limitations during the productive process. Between implemented strategies for reduction of antibiotic use, which are "living microorganisms that confer a health benefit to the host if they are given in adequate quantities"; lactic acid bacteria and yeast are among the most common used microorganism in aquaculture. This investigation, prove the effect of isolated probiotic bacteria from the digestive tract of healthy fish, belonging to specie: Bacillus sp., Bacillus laterosporus, Bacillus subtilis, Lactobacillus sp, and Lactococcus lactis, at different dilutions (10 9 ,10 8 , 10 7 ,10 6 , 10 5 and 10 4 ) in vitro growth of pathogenic bacteria: Citrobacter freundii, Enterobacter sakasakii, Klebsiella oxytoca, Proteus vulgaris, and Vibrio fluvialis, isolated from kidney of sick fish, cultured and purified through successive inoculations and identificated by the amplification of gene 16S of rRNA (PCR) using universal primers 8 for. (5'-AGACTTTGATCATGGCTCAG-3') and 1492 rev. (5'-TACGGCTACCTTGTTACGACTT-3') and comparison with GENEBANK sequences base. Probiotic strains were previously isolated from the digestive tract of different healthy fish in the laboratory. In order to perform in vitro challenge tests, pathogenic strains were inoculated three times each in BHI agar boxes at a concentration of 1x10 7 CFU mL -1 and subsequently using the well diffusion method, 70 µL from a suspension with each of the probiotic strains were added. Agar boxes were incubated 24 h at 30ºC to observe the formation of inhibition halos. Obtained values from inhibition halos were transformed to qualitative data with the following premise: halo diameter < 2.0 mm negative effect; halo diameter > 2.0 mm positive effect. In this study, it was determined that probiotic strains B. subtilis was the one that gave better results to inhibit the growth of pathogenic bacteria P. vulgaris, E. sakazakii, V. fluvialis, K. oxytoca and C. freundii in most of used dilutions. Making it a strain with high potential in aquaculture. Key words: Growth, halos, probiotics, bacteria, sensibility. RESUMEN La acuicultura de especies ornamentales es una actividad económica en franco crecimiento, tanto a nivel mundial como en México, en donde tiene particular desarrollo lo correspondiente a especies dulceacuícolas. Las enfermedades infeccionas producidas por hongos, bacterias y virus, están consideradas una de las limitantes principales durante el proceso productivo. Entre las estrategias implementadas para disminuir el uso de antibióticos para el control de patógenos, se encuentra el control biológico mediante el uso de organismos probióticos, los cuales son "microorganismos vivos los cuales, administrados en cantidades adecuadas, confieren un beneficio en la salud del hospedador"; entre los de uso más común en acuicultura se encuentran las lactobacterias y las levaduras. En el presente trabajo, se probó el efecto de bacterias probióticas aisladas del tracto digestivo de peces sanos, pertenecientes a las especies: Bacillus sp., Bacillus laterosporus, Bacillus subtilis, Lactobacillus sp, y Lactococcus lactis, a diferentes diluciones (10 9 ,10 8 , 10 7 ,10 6 , 10 5 y 10 4 ) en el crecimiento in vitro de las bacterias patógenas: Citrobacter freundii, Enterobacter sakasakii, Klebsiella oxytoca, Proteus vulgaris y Vibrio fluvialis, aisladas del riñón de peces enfermos, cultivadas y purificadas a través de resiembras sucesivas e identificadas mediante la amplificación del gen 16S del ARNr (PCR) utilizando los primers universales 8 for. 24 AGACTTTGATCATGGCTCAG-3') y 1492 rev. (5'-TACGGCTACCTTGTTACGACTT-3') y su comparación con la base de secuencias GENEBANK. Las cepas probióticos fueron aisladas previamente del tracto intestinal de diversos peces sanos en el laboratorio. Para llevar a cabo las pruebas de desafío in vitro, las cepas patógenas se sembraron por triplicado en cajas de agar BHI a una concentración de 1x10 7 UFC mL -1 y posteriormente, utilizando el método de difusión en pozos, se adicionaran 70 µL de una suspensión con cada una de las cepas probióticas Las placas se incubaron durante 24 h a 30ºC para observar la formación de halos de inhibición. Los valores obtenidos de los halos de inhibición fueron transformados a datos cualitativos con la siguiente premisa: diámetro halo < 2.0 mm efecto negativo; diámetro de halo > 2.0 mm efecto positivo. En este estudio, se determinó que la cepas probiótica B. subtilis fue la que dio mejores resultados al inhibir el crecimiento de las bacterias patógenas P. vulgaris, E. sakazakii, V. fluvialis, K. oxytoca y C. freundii en la mayoría de las diluciones utilizadas. Por lo que es una cepa con alto potencial en acuicultura
A genetic variant in the LDLRpromoter is responsible for part of the LDL-cholesterol variability in primary hypercholesterolemia
Stringy effects in black hole decay
We compute the low energy decay rates of near-extremal three(four) charge
black holes in five(four) dimensional N=4 string theory to sub-leading order in
the large charge approximation. This involves studying stringy corrections to
scattering amplitudes of a scalar field off a black hole. We adapt and use
recently developed techniques to compute such amplitudes as near-horizon
quantities. We then compare this with the corresponding calculation in the
microscopic configuration carrying the same charges as the black hole. We find
perfect agreement between the microscopic and macroscopic calculations; in the
cases we study, the zero energy limit of the scattering cross section is equal
to four times the Wald entropy of the black hole.Comment: 32 page
Infraestructura tecnológica de servicios semánticos para la Web Semántica
This project aims at creating a network of distributed interoperable semantic services for
building more complex ones. These services will be available in semantic Web service
libraries, so that they can be invoked by other systems (e.g., semantic portals, software
agents, etc.). Thus, to accomplish this objective, the project proposes:
a) To create specific technology for developing and composing Semantic Web Services.
b) To migrate the WebODE ontology development workbench to this new distributed
interoperable semantic service architecture.
c) To develop new semantic services (ontology learning, ontology mappings,
incremental ontology evaluation, and ontology evolution).
d) To develop technological support that eases semantic portal interoperability, using
Web services and Semantic Web Services.
The project results will be open source, so as to improve their technological transfer. The
quality of these results is ensured by a benchmarking process.
Keywords: Ontologies and Semantic We
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