UNA REPRESENTACIÓN DE LA CURVATURA PARA CONEXIONES GENERALIZADAS

En la física clásica hay sistemas que se modelan en términos de conexiones sobre haces principales. Un objeto fundamental en la descripci ´n de dichos sistemas es la curvatura de la conexión. Nosotros consideramos el espacio de conexiones suaves en haces principales sobre variedades compactas suaves S en el caso abeliano. Nuestra primera meta es extender el conjunto de conexiones suaves a un espacio afín de O de ”conexiones generalizadas” el cual se construye como un límite proyectivo de una sucesión de espacios afines de dimensión finita Oi . La finalidad de nuestra construcción tiene dos objetivos: por un lado, es describir ”observables asociadas a la curvatura”, es decir, funciones FU , que extiendan la noción de integral de la curvatura (o ”flujos”) de una conexión en una superficie lineal a pedazos, U ? S. Por otro lado, nuestra meta es describir medidas de probabilidad en el espacio de conexiones generalizadas O. Las funciones FU deben ser medibles y tener como dominio el soporte de las medidas de probabilidad consideradas. El punto de partida para la construcción de los espacios afines Oi , i ? N, es una sucesión de descomposiciones celulares Ci de S llamadas ”escalas”; para las cuales se define una noción de ”refinamiento”. Los puntos ? ? Oi corresponden a los valores de los flujos a través de la colección de todas las superficies simpliciales en dicha escala. Esta construcción permite que los flujos FU a cada escala estén bien definidos, para superficies simpliciales U ? S a una escala Ci . Además gracias a que las superficies de una escala Ci se incluyen en las superficies a escala Ci+1 , se pueden obtener flujos a escalas gruesas, a partir de escalas finas. Es decir, existen submersiones de ”engrosamiento”, pi+1,i : Oi+1 Oi , a partir de las cuales se define el líimite proyectivo O := lim Oi . Nuestra segunda meta es definir medidas de probabilidad en O , y para ello consideramos ciertas medidas de probabilidad gaussianas, obtenidas a partir de una sucesión de gaussianas de dimensión finita en Oi , compatibles con el engrosamiento pi+1,i . A partir de una estructura adicional sobre S dada por una métrica riemanniana g, es posible definir explícitamente a partir de la forma de área de dicha métrica, ejemplos de medidas gaussianas ?,en O

A Poisson Algebra for Abelian Yang-Mills Fields on Riemannian Manifolds with Boundary

We define a family of observables for abelian Yang-Mills fields associated to compact regions U ⊆ M with smooth boundary in Riemannian manifolds. Each observable is parametrized by a first variation of solutions and arises as the integration of gauge invariant conserved current along admissible hypersurfaces contained in the region. The Poisson bracket uses the integration of a canonical multisymplectic current

Soluciones periódicas para un modelo del volumen de un tumor con tratamiento periódico

In this work, we consider the dynamics of a model for tumor volume growth under a drug periodic treatment targeting the process of angiogenesis within the vascularized cancer tissue. We give sufficient conditions for the existence and uniqueness of a global attractor consisting of a periodic solution. This conditions happen to be satisfied by values of the parameters tested for realistic experimental data. Numerical simulations are provided illustrating our findings.En este trabajo, consideramos la dinámica de un modelo para el crecimiento del volumen de un tumor bajo un tratamiento periódico de medicamentos dirigido al proceso de angiogénesis dentro del tejido vascularizado del cáncer. Damos condiciones suficientes para la existencia y la unicidad de una solución periódica la cual es globalmente atractora. Estas condiciones se cumplen con los valores de los parámetros probados en datos experimentales reales. Se proporcionan simulaciones numéricas que ilustran nuestros resultados

Negotiating Emotional Support: Sober Gay Latinos and Their Families

This study explores how sober gay Latino men obtain support from their families. Familial ties can be a protective health factor, yet many gay Latinos experience rejection from family members because of their sexuality. There are very few studies that examine the extent and quality of emotional support from kin for this population. Understanding family dynamics within the context of recovery and sexuality can increase our understanding of how to leverage family ties to develop alcohol abuse interventions. The study was conducted semi-structured interviews with 30 sober gay Latinos using a grounded theory approach. Analyses of the qualitative data identified the following themes: Family values shaped the participants’ perception of their range of choices and emotional responses; participants reported feeling loved and supported even when sexuality was not discussed with parents; and family support for sobriety is essential. Findings suggest that familial ties shape perceptions of support and importance of disclosing sexual identity. Family support often results from agreements about sexual identity disclosure, and some families can overcome cultural and religious taboos on sexuality. Future studies should investigate families that negotiate acceptance with their gay members, and whether they exhibit heterosexual biases that may influence the psychological stress of gay Latino men who wish to be sober

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licenseBackground: Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide. Methods: A multimethods analysis was performed as part of the GlobalSurg 3 study—a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital. Findings: Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3·85 [95% CI 2·58–5·75]; p<0·0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63·0% vs 82·7%; OR 0·35 [0·23–0·53]; p<0·0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer. Interpretation: Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised. Funding: National Institute for Health and Care Research