Speed of wave-front solutions to hyperbolic reaction-diffusion equations

The asymptotic speed problem of front solutions to hyperbolic reaction-diffusion (HRD) equations is studied in detail. We perform linear and variational analyses to obtain bounds for the speed. In contrast to what has been done in previous work, here we derive upper bounds in addition to lower ones in such a way that we can obtain improved bounds. For some functions it is possible to determine the speed without any uncertainty. This is also achieved for some systems of HRD (i.e., time-delayed Lotka-Volterra) equations that take into account the interaction among different species. An analytical analysis is performed for several systems of biological interest, and we find good agreement with the results of numerical simulations as well as with available observations for a system discussed recently

Automatic generation of active coordinates for quantum dynamics calculations: application to the dynamics of benzene photochemistry

A new practical method to generate a subspace of active coordinates for quantum dynamics calculations is presented. These reduced coordinates are obtained as the normal modes of an analytical quadratic representation of the energy difference between excited and ground states within the complete active space self-consistent field method. At the Franck-Condon point, the largest negative eigenvalues of this Hessian correspond to the photoactive modes: those that reduce the energy difference and lead to the conical intersection; eigenvalues close to 0 correspond to bath modes, while modes with large positive eigenvalues are photoinactive vibrations, which increase the energy difference. The efficacy of quantum dynamics run in the subspace of the photoactive modes is illustrated with the photochemistry of benzene, where theoretical simulations are designed to assist optimal control experiments

Nuclear relaxation contribution to static and dynamic (infinite frequency approximation) nonlinear optical properties by means of electrical property expansions: Application to HF, CH4, CF4, and SF6

Electrical property derivative expressions are presented for the nuclear relaxation contribution to static and dynamic (infinite frequency approximation) nonlinear optical properties. For CF4 and SF6, as opposed to HF and CH4, a term that is quadratic in the vibrational anharmonicity (and not previously evaluated for any molecule) makes an important contribution to the static second vibrational hyperpolarizability of CF4 and SF6. A comparison between calculated and experimental values for the difference between the (anisotropic) Kerr effect and electric field induced second-harmonic generation shows that, at the Hartree-Fock level, the nuclear relaxation/infinite frequency approximation gives the correct trend (in the series CH4, CF4, SF6) but is of the order of 50% too small

Desarrollo y validación de ensayos rápidos para la detección de aeroalérgenos ocupacionales/ambientales: soja i proteinas séricas de paloma

Tanto el asma ocupacional como la neumonitis por hipersensibilidad, como es el pulmón del cuidador de aves, son patologías respiratorias que se pueden prevenir o disminuir su aparición mediante la evitación de la fuente antigénica. Para poder actuar de forma preventiva es de utilidad el disponer de ensayos rápidos que sean capaces de estimar la presencia de alérgeno de forma inmediata. En el marco de este proyecto de dos años de duración tenemos por objeto el desarrollar y estandarizar dos métodos rápidos, inmunocromatográficos, para la determinación de alérgenos de soja y de proteínas séricas de paloma. Alérgenos que han sido seleccionados por su importancia en el medio como agentes causales de asma y neumonitis por hipersensibilidad, respectivamente. También tenemos por objeto determinar la carga de alérgeno de soja en la fracción de partículas menores de 10 micrómetros (PM10) en los alrededores del puerto de Barcelona y comprarla con los niveles en los filtros de partículas suspendidas totales (TSP). Como pasos previos al desarrollo de los ensayos rápidos se han producido anticuerpos específicos frente al extracto de cáscara de soja de bajo peso molecular y frente al suero de paloma, se ha desarrollado un ELISA tipo sándwich para cada alérgeno y parte de los anticuerpos se ha conjugado con oro coloidal. El ensayo inmunocromatográfico para la soja presenta un límite de detección de 6.25ng/ml y ha sido validado mediante el análisis de 119 muestras ambientales, presentando una elevada especificidad y sensibilidad. El ensayo inmunocromatográfico para la determinación de antígenos séricos de paloma requiere ser validado. Mediante un métodos de ELISA de inhibición se han determinado los niveles de alérgeno de soja en filtros PM10 y TSP. A pesar de la buena correlación entre los niveles de alérgeno en ambos filtros, se observó una amplia variación en la proporción PM10/TSP entre días.

Desarrollo de tecnología Bulk Acoustic Wave

El creciente uso de dispositivos móviles y el gran avance en la mejora de las aplicaciones y sistemas inalámbricos ha impulsado la demanda de filtros paso banda miniaturizados, que trabajen a altas frecuencias y tengan unas prestaciones elevadas. Los filtros basados en resonadores Bulk Acoustic Wave (BAW) están siendo la mejor alternativa a los filtros Surface Acoustic Wave (SAW), ya que funcionan a frecuencias superiores, pueden trabajar a mayores niveles de potencia y son compatibles con la tecnología CMOS. El filtro en escalera, que utiliza resonadores BAW, es de momento la mejor opción, debido a su facilidad de diseño y su bajo coste de fabricación. Aunque el filtro con resonadores acoplados (CRF) presenta mejores prestaciones como mayor ancho de banda, menor tamaño y conversión de modos. El problema de este tipo de filtros reside en su complejidad de diseño y su elevado coste. Este trabajo lleva a cabo el diseño de un CRF a partir de unas especificaciones bastante estrictas, demostrando sus altas prestaciones a pesar de su mayor inconveniente: el coste de fabricación.

Inter-rater agreement and reliability of the COSMIN (COnsensus-based Standards for the selection of health status Measurement Instruments) Checklist

Background: The COSMIN checklist is a tool for evaluating the methodological quality of studies on measurement properties of health-related patient-reported outcomes. The aim of this study is to determine the inter-rater agreement and reliability of each item score of the COSMIN checklist (n = 114). Methods: 75 articles evaluating measurement properties were randomly selected from the bibliographic database compiled by the Patient-Reported Outcome Measurement Group, Oxford, UK. Raters were asked to assess the methodological quality of three articles, using the COSMIN checklist. In a one-way design, percentage agreement and intraclass kappa coefficients or quadratic-weighted kappa coefficients were calculated for each item. Results: 88 raters participated. Of the 75 selected articles, 26 articles were rated by four to six participants, and 49 by two or three participants. Overall, percentage agreement was appropriate (68% was above 80% agreement), and the kappa coefficients for the COSMIN items were low (61% was below 0.40, 6% was above 0.75). Reasons for low inter-rater agreement were need for subjective judgement, and accustom to different standards, terminology and definitions.Conclusions: Results indicated that raters often choose the same response option, but that it is difficult on item level to distinguish between articles. When using the COSMIN checklist in a systematic review, we recommend getting some training and experience, completing it by two independent raters, and reaching consensus on one final rating. Instructions for using the checklist are improved.

Bridging DSGE models and the raw data

A method to estimate DSGE models using the raw data is proposed. The approachlinks the observables to the model counterparts via a flexible specification which doesnot require the model-based component to be solely located at business cycle frequencies,allows the non model-based component to take various time series patterns, andpermits model misspecification. Applying standard data transformations induce biasesin structural estimates and distortions in the policy conclusions. The proposed approachrecovers important model-based features in selected experimental designs. Twowidely discussed issues are used to illustrate its practical use.

Multiple filtering devices for the estimation of cyclical DSGE models

We propose a method to estimate time invariant cyclical DSGE models using the informationprovided by a variety of filters. We treat data filtered with alternative procedures as contaminated proxies of the relevant model-based quantities and estimate structural and non-structuralparameters jointly using a signal extraction approach. We employ simulated data to illustratethe properties of the procedure and compare our conclusions with those obtained when just onefilter is used. We revisit the role of money in the transmission of monetary business cycles.

Estimating learning models from experimental data

We study the statistical properties of three estimation methods for a model of learning that is often fitted to experimental data: quadratic deviation measures without unobserved heterogeneity, and maximum likelihood withand without unobserved heterogeneity. After discussing identification issues, we show that the estimators are consistent and provide their asymptotic distribution. Using Monte Carlo simulations, we show that ignoring unobserved heterogeneity can lead to seriously biased estimations in samples which have the typical length of actual experiments. Better small sample properties areobtained if unobserved heterogeneity is introduced. That is, rather than estimating the parameters for each individual, the individual parameters are considered random variables, and the distribution of those random variables is estimated.

An Efficient Nominal Unification Algorithm

Nominal Unification is an extension of first-order unification where terms can contain binders and unification is performed modulo α equivalence. Here we prove that the existence of nominal unifiers can be decided in quadratic time. First, we linearly-reduce nominal unification problems to a sequence of freshness and equalities between atoms, modulo a permutation, using ideas as Paterson and Wegman for first-order unification. Second, we prove that solvability of these reduced problems may be checked in quadràtic time. Finally, we point out how using ideas of Brown and Tarjan for unbalanced merging, we could solve these reduced problems more efficiently

Homotopy Batalin-Vilkovisky algebras

This paper provides an explicit cofibrant resolution of the operad encoding Batalin-Vilkovisky algebras. Thus it defines the notion of homotopy Batalin-Vilkovisky algebras with the required homotopy properties. To define this resolution we extend the theory of Koszul duality to operads and properads that are defind by quadratic and linear relations. The operad encoding Batalin-Vilkovisky algebras is shown to be Koszul in this sense. This allows us to prove a Poincare-Birkhoff-Witt Theorem for such an operad and to give an explicit small quasi-free resolution for it. This particular resolution enables us to describe the deformation theory and homotopy theory of BV-algebras and of homotopy BV-algebras. We show that any topological conformal field theory carries a homotopy BV-algebra structure which lifts the BV-algebra structure on homology. The same result is proved for the singular chain complex of the double loop space of a topological space endowed with an action of the circle. We also prove the cyclic Deligne conjecture with this cofibrant resolution of the operad BV. We develop the general obstruction theory for algebras over the Koszul resolution of a properad and apply it to extend a conjecture of Lian-Zuckerman, showing that certain vertex algebras have an explicit homotopy BV-algebra structure.

Estudi per a la construcció de l'EDAR mitjançant filtres verds de la Nou de Gaià (Tarragonès)

El tractament de les aigües en nuclis menors de 2000 habitants es troba pendent de completar per part de l’Agència Catalana de l’Aigua més concretament al corresponent Pla de Sanejament d’Aigües Residuals Urbanes (PSARU). El nucli de La Nou de Gaià (al Tarragonès) es troba pendent de la construcció de la corresponent instal·lació de sanejament, projectada al 2007. Alternativament a les depuradores tradicionals basades en l’ús de formigó (o materials alternatius) i en la despesa elèctrica per assegurar una aeració i una evacuació dels fangs generats, existeixen tecnologies “toves”. Aquestes tecnologies, també conegudes com a “verdes”, es basen en imitar els sistemes naturals maximitzant el seu potencial d’autodepuració. A grans trets existeixen dos formes de depurar les aigües de forma ecològica”: llacunatges (existeix una capa d’aigua lliure) i filtres verds. El present estudi es basa en l’aplicació de filtres verds de morfologia vertical i flux subsuperficial, plantat amb canyes dels generes Scirpus o Phragmites. El resultat han estat 4 bases de 35*35 per a tractar un cabal de 150 m3/d i una població equivalent de 1272.

Graded algebra automorphisms

We consider the Clifford algebra C(q) of a regular quadratic space (V, q) over a field K with its structure of Z/2Z-graded K-algebra. We give a characterization of the group of graded automorphisms of C(q). In the last section we introduce the Z/nZ-graded algebras and we study as well as the group of graded automorphisms for some of them.

Photometric Bgr survey of the distant clusters of galaxies CL 1613+3104 and CL 1600+4109

We present a set of photometric data concerning two distant clusters of galaxies: Cl 1613+3104 (z=0.415) and Cl 1600+4109 (z=0.540). The photometric survey extends to a field of about 4' x 3'. It was performed in 3 filters: Johnson B, and Thuan-Gunn g and r. The sample includes 679 objects in the field of Cl 1613+3104 and 334 objects in Cl 1600+4109.

Photometric and spectroscopic survey of the cluster of galaxies Abell A2218

We present new photometric and spectroscopic observations of objects in the field of the cluster of galaxies Abell 2218. The photometric survey, centered on the cluster core, extends to a field of about 4 x 4 arcmin. It was performed in 5 bands (B,g,r,i and z filters). This sample, which includes 729 objects, is about three times larger than the survey made by Butcher and collaborators (Butcher et al., 1983, Butcher and Oemler, 1984) in the same central region of the field. Only 228 objects appear in both catalogues since our survey covers a smaller region. The spectral range covered by our filters is wider and the photometry is much deeper, up to magnitude 27 in r. The spectroscopic survey concerns 66 objects, on a field comparable to that of Butcher and collaborators. From our observations we calculate the mean redshift of the cluster, 0.1756, and its velocity dispersion, 1370 km/s. The spectral types are determined for many galaxies in the sample by comparing their spectra with synthetic ones from Rocca-Volmerange and Guiderdoni (1988).