The behavior of the best Sobolev trace constant and extremals in thin domains

In this paper, we study the asymptotic behavior of the best Sobolev trace constant and extremals for the immersion W1,p(Ω) Lq(∂Ω) in a bounded smooth domain when it is contracted in one direction. We find that the limit problem, when rescaled in a suitable way, is a Sobolev-type immersion in weighted spaces over a projection of Ω, W1,p(P(Ω), α) Lq(P(Ω), β). For the special case p = q, this problem leads to an eigenvalue problem with a nonlinear boundary condition. We also study the convergence of the eigenvalues and eigenvectors in this case. © 2003 Elsevier Inc. All rights reserved.Fil:Fernández Bonder, J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Martínez, S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Rossi, J.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

C-S-H gels in blended cements: Study by infrared spectroscopy

ICCC 2015, Beijing, China, 13~16 October 2015; http://iccc2015.csp.escience.cn/dct/page/1C-S-H gel is the main product in the Portland cement (PC) hydration. Of their structure and composition depends the cement properties (strength, durability¿). The mixes of others materials with PC provides new cementitious materials with different properties. Understand the changes produces in the hydration products in these blends improves their use. This work studies the changes produced in the C-S-H gel by means Fourier Transform Infrared Spectroscopy (FTIR). Several samples were studied, PC (as reference system), a system formed by PC and calcium aluminate cement (CAC) with a 75/25 ratio, and two system formed by PC, CAC and calcium sulfate (C¿) with an 85/15 ratio of PC/CAC with 3 and 5% of C¿. All samples were cured in two environmental; at the air and under water, in order to observe the influence of curing. The samples were studied at the 6 hours, 7 days, 12 and 32 months of age. Results show in the PC, it changes to lower wavenumbers in the Q2 units positions over time. This fact indicates a little transformation of structure like-tobermorite to structure like-jennite providing a C-S-H less compact. Addition of CAC in PC hydration decreases the migration of Q2 units to lower wavenumbers indicating that C-S-H structure is more compact in this case. When C¿ is included in the system, this migration of Q2 units is lower and the bands are sharper indicating the structure like tobermorite presence. Other effect visible in the spectra is the decrease of bands due to Q1 units with the addition of CAC. The greater presence of aluminates in the system provides substitutions of Si4+ by Al3+ in the C-S-H structure. This fact produces longer chains reducing the units Q1. Different behaviors are observed in the cured conditions showing higher transformation towards structures like-jennite in the samples cured under water. Several conclusions can be drawn of this work. First, it use of infrared spectroscopy as powerful tool in the cement chemistry field. Not only as characterization technique but also it can be used for obtain structural information about cement phases, both hydrated as anhydrous. Regarding addition of other hydraulic materials at PC, the study shows formation of C-S-H more compact that will provide better mechanical properties. Also the cured conditions have influenced about hydrated products structure.Peer Reviewe

Reaction-diffusion equations: a chemical application

Obtenemos soluciones exactas para un sistema de reacción-difusión asociado a una reacción cubica autocatalítica entre dos sustancias químicas según la regla con tasa . Para obtener dichas soluciones empleamos una transformación de onda

A 2D finite volume simulation tool to enable the assessment of combined hydrological and morphodynamical processes in mountain catchments

Nowadays, the great power of modern computers allows to develop computational models able to deal with simulations of several coupled phenomena over detailed complex topography. An efficient and properly calibrated computational model represents a useful tool to provide insight into the catchment dynamics at hydrological and geomorphological levels. In addition, it allows to develop detailed risk management and conservation plans. In this work, we present a coupled surface-groundwater distributed flow model with hydrological (rainfall and infiltration) and geomorphological (suspended and bed load sediment transport) components. The coupled model is applied to well characterized experimental catchments that are used as realistic test cases. The calibration of the water flow model response to rainfall is performed by means of the fitting to experimental outlet hydrographs of the results supplied by a coupled formulation of 2D Shallow Water Equations and 2D Darcy's law for saturated porous media connected via suitable infiltration laws. The calibration of a suspended and bed load model is also addressed by means of the fitting to experimental outlet sedigraphs. The numerical results show a good agreement between numerical and observed hydrographs and sedigraphs, significantly improving previous published simulations. Additionally, the need to repeat the simulations in the calibration processes is no longer an unapproachable problem

Sex differences in comorbidity between substance use and mental health in adolescents: Two sides of the same coin

Background: This study aims to evaluate sex differences in alcohol and cannabis use and mental health disorders (MHD) in adolescents, and to evaluate the predictive role of mental health disorders for alcohol and cannabis use disorders (AUD and CUD respectively). Method: A sample of 863 adolescents from the general population (53.7% girls, Mage = 16.62, SD = 0.85) completed a computerized battery including questions on substance use frequency, the Brief Symptom Inventory, the Cannabis Problems Questionnaire for Adolescents - Short version, the Rutgers Alcohol Problem Index and the DSM-IV-TR criteria for AUD and CUD. Bivariate analyses and binary logistic regressions were performed. Results: Girls presented significantly more mental health problems and a higher prevalence of comorbidity between SUD and MHD. Obsessivecompulsive symptoms and phobic anxiety indicated a higher risk of AUD, whereas depression and interaction between hostility and obsessivecompulsive disorder indicated a higher risk of CUD. Conclusions: Comorbidity between SUD and MHD is high among adolescents, and significantly higher among girls. Antecedentes: el objetivo de esta investigación es evaluar las diferencias de sexo en el uso de cannabis y alcohol y en trastornos de salud mental TSM en adolescentes, y el rol predictivo de los TSM sobre los trastornos por uso de alcohol y cannabis (TUA y TUC, respectivamente). Método: una muestra de 863 adolescentes de la población general (53, 7% chicas, edad media = 16.62, DT = 0, 85) completaron una batería informatizada sobre la frecuencia de uso de sustancias, el Inventario Breve de Síntomas, el Cuestionario de Problemas por Consumo de Cannabis - versión breve, el Índice de Rutgers de Problemas con el Alcohol y los criterios DSM-IV-TR para el TUA y TUC. Se realizaron análisis bivariados y de regresión logística binaria. Resultados: las chicas presentaron significativamente más problemas de salud mental y mayor prevalencia de comorbilidad entre TUS y TSM. El trastorno obsesivo-compulsivo (TOC) y la ansiedad fóbica indicaron un mayor riesgo de TUA, mientras que la depresión y la interacción entre hostilidad y TOC indicaron mayor riesgo de TUC. Conclusiones: la comorbilidad entre TUS y TSM es alta entre los adolescentes, y significativamente mayor entre las chicas

El conocimiento del horizonte matemático: más allá de conectar el presente con el pasado y el futuro

Este trabajo se inscribe en el contexto de un estudio longitudinal dirigido a investigar factores relacionados con el conocimiento del profesor que intervienen en la adquisición de la competencia matemática desde la educación primaria a la secundaria. Partimos de la conceptualización del Conocimiento Matemático para la Enseñanza (MKT) y concretamente el Conocimiento del Horizonte Matemático (HCK), cuya caracterización en términos de conexiones es una de las aportaciones teóricas de nuestro trabajo. Las Trayectorias Hipotéticas en el Horizonte Matemático que hemos construido a partir del análisis de la práctica del aula han resultado ser una herramienta metodológica adecuada para conceptualizar teóricamente el Conocimiento del Horizonte Matemático

Immunoexpression of E-cadherin and Vimentin in Normal Oral Mucosa, Oral Epithelial Displasia and Oral Squamous Cell Carcinoma

Indexación: Web of Science; Scopus; Scielo.El objetivo fue evaluar la inmunoexpresión de E-cadherina y Vimentina en mucosa oral normal (MON), displasia epitelial oral (DEO) y carcinoma oral de células escamosas (COCE). Se realizó un estudio descriptivo de una serie de casos analizandolos mediante técnica de inmunohistoquímica contra E-cadherina y Vimentina 16 muestras de MON, 16 de DEO y 19 de COCE. La inmunotinción fue evaluada cualitativamente considerando extensión e intensidad para E-cadherina e intensidad para Vimentina. El análisis de la extensión e intensidad de la inmunotinción de E-cadherina y Vimentina según diagnóstico reveló una asociación estadísticamente significativa (p<0,001). Siendo la expresión de E-cadherina más alta en MON, seguido por DEO y más baja en COCE, inversamente a lo que se observó con Vimentina. El presente estudio reveló la subregulación del marcador molecular E-cadherina junto con la expresión aberrante por parte de células epiteliales del marcador mesenquimal Vimentina en muestras de MON, DEO y COCE.The aim was to evaluate the expression of E-cadherin and Vimentin in oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC), in comparison with normal oral mucosa (NOM) in a descriptive case study using immunohistochemistry. A total of fifty-one (N=51) histological samples were included; as follows: n = 16 (NOM), n = 16 (OED) and n = 19 (OSCC). All samples were analyzed using immunohistochemistry against the expression of E-cadherin and Vimentin. Immunostaining was qualitatively evaluated by extent and intensity of its expression for E-cadherin and intensity for Vimentin. Extension and intensity analysis of E-cadherin and Vimentin immunostaining according to group revealed a statistically significant association (r<0.001). E-cadherin expression was found to be highest in NOM followed by OED and lowest in OSCC, inverse to what was observed with Vimentin. The present study revealed the down regulation of the molecular marker E-cadherin, suggestive of reduction in dysplastic cells on comparison to NOM cells, and aberrant expression of the mesenchymal marker Vimentin by epithelial cells in samples of NOM, OED and OSCC; questioning their value as a prognostic marker.http://ref.scielo.org/pk8s6

νμ\nu_\mu disappearance at the SPL, T2K-I and the Neutrino Factory

We study the $\nu_\mu$ disappearance channel at T2K-phase I and the SPL and analyse the achievable reduction of present uncertainties in $\theta_{23}$ and $\Delta m^2_{23}$. We analyse the impact of discrete ambiguities in sign($\Delta m^2{23}$) and sign($2 \tan \theta_{23}$). We show how the disappearance channel at the Neutrino Factory is complementary to the ``golden'' and ``silver'' appearance channels and can be used to reduce the eightfold-ambiguity problem in ($\theta_{13}-\delta$).Comment: 2 pages, 3 epsfig; NUFACT'05, 21-26 June 2005, Frascat

Strategic planning for community sustainability in model forests: Case study of the Yoro model forest, Honduras

El estudio plantea una planificación estratégica de desarrollo en los Bosques Modelo a partir del estudio del caso del Bosque Modelo de Yoro, en Honduras, en donde el sector de la industria maderera y en concreto el subsector de carpintería y mueble, parece tener más ventajas competitivas para producir productos de exportación que generen riqueza en la zona, dada la escasa capacidad de compra de la región. A este subsector se le realiza un Análisis estratégico, una Elección estratégica y una Implementación estratégica determinando que el desarrollo del subsector podría pasar por crear una cooperativa capaz de suministrar partes de muebles a una empresa de carácter internacional que tenga como estrategia comercial la venta de muebles naturales, ecológicos y que esté comprometida socialment