The SEIQS stochastic epidemic model with external source of infection

This paper deals with a stochastic epidemic model for computer viruses with latent and quarantine periods, and two sources of infection: internal and external. All sojourn times are considered random variables which are assumed to be independent and exponentially distributed. For this model extinction and hazard times are analyzed, giving results for their Laplace transforms and moments. The transient behavior is considered by studying the number of times that computers are susceptible, exposed, infectious and quarantined during a period of time (0, t] and results for their joint and marginal distributions, moments and cross moments are presented. In order to give light this analysis, some numerical examples are showed

Extreme values in SIR epidemic models with two strains and cross-immunity

The paper explores the dynamics of extreme values in an SIR (susceptible → infectious → removed) epidemic model with two strains of a disease. The strains are assumed to be perfectly distinguishable, instantly diagnosed and each strain of the disease confers immunity against the second strain, thus showing total cross-immunity. The aim is to derive the joint probability distribution of the maximum number of individuals simultaneously infected during an outbreak and the time to reach such a maximum number for the first time. Specifically, this distribution is analyzed by distinguishing between a global outbreak and the local outbreaks, which are linked to the extinction of the disease and the extinction of particular strains of the disease, respectively. Based on the mass function of the maximum number of individuals simultaneously infected during the outbreak, we also present an iterative procedure for computing the final size of the epidemic. For illustrative purposes, the twostrain SIR-model with cross-immunity is applied to the study of the spread of antibiotic-sensitive and antibiotic-resistant bacterial strains within a hospital ward

Técnicas de muestreo y estadísticas oficiales

Fac. de Estudios Estadísticospu

Definición y estudios de redes bayesianas aplicadas a ciencias de la salud y de la vida

Las redes bayesianas son modelos gráficos probabilísticos que expresan las relaciones de dependencia condicional en un conjunto de variables. Desde su concepción, las redes bayesianas han estado profundamente ligadas a las Ciencias de la Salud y de la Vida, especialmente en el área clínica. Existe una bibliografía extensa sobre aplicaciones de las redes bayesianas a este ámbito. Sin embargo, el análisis de algoritmos de aprendizaje de redes y parámetros, y su aptitud en función de factores como la cantidad de variables, la naturaleza de los datos o la complejidad de la estructura de dependencia no es un tema común en la literatura. En este trabajo, analizamos la aplicación de estas técnicas a problemas descritos en la bibliografía, exploramos el software bnlearn disponible en el lenguaje de programación R documentando nuestro código y evaluamos las estrategias de aprendizaje que mejor se ajustan a cada tipo de datos. Esperamos con ello aportar conocimiento sobre las redes bayesianas y proporcionar un punto de partida para su estudio a profesionales sanitarios e investigadores

Desarrollo de herramientas on line para estudiar la inserción laboral de los graduados de la Universidad Complutense

Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasFALSEsubmitte

Gamificación en el aula con Kahoot! en la Facultad de Estudios Estadísticos

Memoria final del proyecto de innovación docente titulado: "Gamificación en el aula con Kahoot! en la Facultad de Estudios Estadísticos

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

Background 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

Sistemas de colas con reintentos: análisis de los eventos bloqueados y exitosos

El objetivo de esta tesis es profundizar en los sistemas de colas con reintentos M/M/c y M/G/1 mediante el estudio de nuevos descriptores como son el número de eventos exitosos y bloqueados. El interés de estos descriptores radica en la idea de aumentar el conocimiento sobre el grupo de clientes de la órbita, es decir, aquellos clientes que tras haber abandonado el sistema sin obtener servicio vuelven a intentarlo transcurrido un tiempo. En la mayoría de las aplicaciones es imposible discernir si un cliente que obtiene servicio ha llegado al sistema por primera vez o proviene de la órbita. La diferenciación entre eventos exitosos y bloqueados además proporciona información sobre la dificultad de acceso al servicio solicitado. En el Capítulo 1 se hace una breve descripción de los modelos de colas con reintentos y se recogen resultados correspondientes a la distribución límite del estado del sistema así como a descriptores relacionados con el periodo de ocupación y el tiempo de espera en los modelos M/M/c y M/G/1 con reintentos. En el Capítulo 2 se definen los descriptores de interés como el número de eventos exitosos y bloqueados durante un periodo de ocupación, estudiándose su distribución en el modelo M/M/c con reintentos. El estudio de la distribución del número de eventos exitosos y bloqueados durante un periodo de ocupación en el sistema M/G/1 con reintentos se desarrolla en el Capítulo 3. Para este sistema resulta especialmente complicado el estudio del número de reintentos bloqueados, por lo que se proponen dos aproximaciones diferentes para la obtención de su distribución. Por último, en el Capítulo 4 se lleva a cabo un análisis transitorio de los nuevos descriptores. Se estudia el comportamiento del número de eventos exitosos y bloqueados durante un intervalo de tiempo fijo en los modelos M/M/c y M/PH/1 con reintento

Cumulative and maximum epidemic sizes for a nonlinear seir stochastic model with limited resources

The paper deals with a stochastic SEIR model with nonlinear incidence rate and limited resources for a treatment. We focus on a long term study of two measures for the severity of an epidemic: The total number of cases of infection and the maximum of individuals simultaneously infected during an outbreak of the communicable disease. Theoretical and computational results are numerically illustrated.Ministerio de Ciencia, Innovación y Universidades de EspañaComisión EuropeaDepto. de Estadística y Ciencia de los DatosFac. de Estudios EstadísticosTRUEpu

A three-dimensional Oral health-related quality of life framework for temporomandibular joint disorders: A structural analysis of the Oral Health Impact Profile-14

Objectives: the objective is to analyze the structure and relationship between the components of the Oral health-related quality of life using the Oral Health Impact Profile-14 (OHIP-14) for patients with temporomandibular joint disorders (TMJD). Methods: two studies were examinated by means of factor analysis, multidimensional scaling and their spatial display in a cross-sectional design (n = 153). Results: three-dimensional solutions with an adequate fit were found: residual distribution, root mean square of residuals (RMSR) = 0.04, Goodness of Fit Index (GFI) = 0.96, and Adjusted Goodness of Fit Index (AGFI) = 0.93; and Stress I = 0.023, respectively. The overall ordinal alpha coefficient was 0.92 (CI=0.90 to 0.94). The ordinal alpha coefficients for functional impact, psychosocial impact and psychological impact factors were 0.87 (CI=0.84 to 0.90), 0.88 (CI=0.84 to 0.91) and 0.78 (CI= 0.72 to 0.83), respectively. Item 9 was the most central, followed by 7 and 11. Items 1 and 2 had minor associations. There was no evidence of differences between centers: edge weight differences (M = 0.226, p = 0.94), global strength invariance test (S = 1.88, p = 0.1), centrality invariance test (p >0.05), edge invariance test (p >0.05). Conclusions: the links between the dimensions and the items seem to involve psychological components. Oral health-related quality of life emerged as a three-dimensional structure (Functional Impact, Psychosocial Impact and Psychological Impact) of functional and psychosocial elements in which physical, psychological, and social disability were essential, while theoretical functional limitation was least important. Clinical significance: the three-dimensional OHRQoL system for temporomandibular disorders (TMD) is a worthwhile alternative to interpret psychological and psychosocial aspects.Depto. de Estadística y Ciencia de los DatosFac. de Estudios EstadísticosTRUEpu