Maximal partial line spreads of non-singular quadrics

For n >= 9 , we construct maximal partial line spreads for non-singular quadrics of for every size between approximately and , for some small constants and . These results are similar to spectrum results on maximal partial line spreads in finite projective spaces by Heden, and by Gacs and SzAnyi. These results also extend spectrum results on maximal partial line spreads in the finite generalized quadrangles and by Pepe, Roing and Storme

Identifying codes in vertex-transitive graphs and strongly regular graphs

We consider the problem of computing identifying codes of graphs and its fractional relaxation. The ratio between the size of optimal integer and fractional solutions is between 1 and 2ln(vertical bar V vertical bar) + 1 where V is the set of vertices of the graph. We focus on vertex-transitive graphs for which we can compute the exact fractional solution. There are known examples of vertex-transitive graphs that reach both bounds. We exhibit infinite families of vertex-transitive graphs with integer and fractional identifying codes of order vertical bar V vertical bar(alpha) with alpha is an element of{1/4, 1/3, 2/5}These families are generalized quadrangles (strongly regular graphs based on finite geometries). They also provide examples for metric dimension of graphs

Anderson acceleration for contractive and noncontractive operators

A one-step analysis of Anderson acceleration with general algorithmic depths is presented. The resulting residual bounds within both contractive and noncontractive settings clearly show the balance between the contributions from the higher and lower order terms, which are both dependent on the success of the optimization problem solved at each step of the algorithm. In the contractive setting, the bounds sharpen previous convergence and acceleration results. The bounds rely on sufficient linear independence of the differences between consecutive residuals, rather than assumptions on the boundedness of the optimization coefficients. Several numerical tests illustrate the analysis primarily in the noncontractive setting, and demonstrate the use of the method on a nonlinear Helmholtz equation and the steady Navier-Stokes equations with high Reynolds number in three spatial dimensions

Expression of Intestine-Specific Antigen Reveals Novel Pathways of CD8 T Cell Tolerance Induction

AbstractReactivity to intestinal epithelium-specific antigen was studied by transgenic expression of cytosolic ovalbumin controlled by an enterocyte-specific promoter. Transferred OVA-specific CD8 cells (OT-I) preferentially expanded in mucosal lymphoid tissues and the epithelium but failed to cause tissue damage. In contrast, concomitant VSV-ova infection induced OT-I-mediated epithelial cell destruction that correlated with antigen density. OT-I cells retained in the epithelium exhibited high levels of lytic activity but were unable to produce cytokines. The mice were systemically tolerant to OVA since endogenous CD8 cells were nonresponsive to VSV-ova infection. Thus, intestinal antigen gained access to peripheral tissues via absorption from effete epithelial cells. This system demonstrated a requirement for inflammation to drive pathogenic autoreactivity against enterocytes and identified pathways of intestine-specific immunoregulation

Photoelastic coupling in gallium arsenide optomechanical disk resonators

We analyze the magnitude of the radiation pressure and electrostrictive stresses exerted by light confined inside GaAs semiconductor WGM optomechanical disk resonators, through analytical and numerical means, and find the electrostrictive force to be of prime importance. We investigate the geometric and photoelastic optomechanical coupling resulting respectively from the deformation of the disk boundary and from the strain-induced refractive index changes in the material, for various mechanical modes of the disks. Photoelastic optomechanical coupling is shown to be a predominant coupling mechanism for certain disk dimensions and mechanical modes, leading to total coupling g$_{om}$ and g$_0$ reaching respectively 3 THz/nm and 4 MHz. Finally, we point towards ways to maximize the photoelastic coupling in GaAs disk resonators, and we provide some upper bounds for its value in various geometries

Clasificación de errores gramaticales colocacionales en textos de estudiantes de español

Arbitrary recurrent word combinations (collocations) are a key in language learning. However, even advanced students have difficulties when using them. Efficient collocation aiding tools would be of great help. Still, existing “collocation checkers” still struggle to offer corrections to miscollocations. They attempt to correct without making any distinction between the different types of errors, providing, as a consequence, heterogeneous lists of collocations as suggestions. Besides, they focus solely on lexical errors, leaving aside grammatical ones. The former attract more attention, but the latter cannot be ignored either if the goal is to develop a comprehensive collocation aiding tool, able to correct all kinds of miscollocations. We propose an approach to automatically classify grammatical collocation errors made by US learners of Spanish as a starting point for the design of specific correction strategies targeted for each type of error.Las combinaciones recurrentes y arbitrarias de palabras (colocaciones) son clave para el aprendizaje de lenguas pero presentan dificultades incluso a los estudiantes m as avanzados. El uso de herramientas eficientes destinadas al aprendizaje de colocaciones supondría una gran ayuda, sin embargo, las que existen actualmente intentan corregir colocaciones erróneas sin diferenciar entre los distintos tipos de errores ofreciendo, como consecuencia, largas listas de colocaciones de muy diversa naturaleza. Además, sólo se consideran los errores léxicos, dejando de lado los gramaticales que, aunque menos frecuentes, no pueden ignorarse si el objetivo es desarrollar una herramienta capaz de corregir cualquier colocación errónea. En el presente trabajo se propone un método de clasificación automática de errores colocacionales gramaticales cometidos por estudiantes de español estadounidenses, como punto de partida para el diseño de estrategias de corrección específicas para cada tipo de error.This work has been funded by the Spanish Ministry of Science and Competitiveness (MINECO), through a predoctoral grant with reference BES-2012-057036, in the framework of the project HARenES, under the contract number FFI2011-30219-C02-02

High frequency GaAs nano-optomechanical disk resonator

Optomechanical coupling between a mechanical oscillator and light trapped in a cavity increases when the coupling takes place in a reduced volume. Here we demonstrate a GaAs semiconductor optomechanical disk system where both optical and mechanical energy can be confined in a sub-micron scale interaction volume. We observe giant optomechanical coupling rate up to 100 GHz/nm involving picogram mass mechanical modes with frequency between 100 MHz and 1 GHz. The mechanical modes are singled-out measuring their dispersion as a function of disk geometry. Their Brownian motion is optically resolved with a sensitivity of 10^(-17)m/sqrt(Hz) at room temperature and pressure, approaching the quantum limit imprecision.Comment: 7 pages, 3 figure

In Situ Raman Analysis of CO\u2082-Assisted Drying of Fruit-Slices

This work explores the feasibility of applying in situ Raman spectroscopy for the online monitoring of the supercritical carbon dioxide (SC-CO\u2082) drying of fruits. Specifically, we investigate two types of fruits: mango and persimmon. The drying experiments were carried out inside an optical accessible vessel at 10 MPa and 313 K. The Raman spectra reveal: (i) the reduction of the water from the fruit slice and (ii) the change of the fruit matrix structure during the drying process. Two different Raman excitation wavelengths were compared: 532 nm and 785 nm. With respect to the quality of the obtained spectra, the 532 nm excitation wavelength was superior due to a higher signal-to-noise ratio and due to a resonant excitation scheme of the carotenoid molecules. It was found that the absorption of CO\u2082 into the fruit matrix enhances the extraction of water, which was expressed by the obtained drying kinetic curve