Maximum likelihood parameter estimation for latent variable models using sequential Monte Carlo

We present a sequential Monte Carlo (SMC) method for maximum likelihood (ML) parameter estimation in latent variable models. Standard methods rely on gradient algorithms such as the Expectation- Maximization (EM) algorithm and its Monte Carlo variants. Our approach is different and motivated by similar considerations to simulated annealing (SA); that is we propose to sample from a sequence of artificial distributions whose support concentrates itself on the set of ML estimates. To achieve this we use SMC methods. We conclude by presenting simulation results on a toy problem and a nonlinear non-Gaussian time series model

Crime in New Orleans: applying the civic community perspective to urban violence

Civic community theory is a macro-level social control perspective that has emerged within the past 10 years as an explanation of community variation in crime rates. The theory is based on the assumption that well-integrated communities are better able to regulate their members’ behaviors than poorly integrated communities. It has been particularly successful in explaining violent crime rates in rural counties or communities, but research has generally ignored the relationship between civic community theory and violent crime in urban areas. The current study aims to determine the applicability of the civic community perspective to urban areas, as a link has not been demonstrated in previous research. To test its applicability, census tract data are analyzed. The link between civic community theory and violent crime, particularly homicide and aggravated assault, is determined using secondary data geocoded to census tracts in Orleans Parish, Louisiana. Data are gathered from the U.S. Census Bureau’s American Community Survey, the Zip Code Business Patterns, and the New Orleans Police Department. Negative binomial regression techniques are utilized after creating a measure to capture any spatial autocorrelation that may exist between census tracts. The results reveal that the protective effects of civic community theory are applicable to violent crime in urban areas. Each civic community measure was found to be negative and significantly related to homicide and aggravated assault counts individually and when combined. Additionally, an interactive effect between civic engagement and resource disadvantage indicated that the protective effect of civic engagement is stronger in areas plagued with high levels of disadvantage. Upon analyzing the standardized percent changes, it was revealed that the strength of the individual civic community measures varies depending on which violent crime is being predicted. Specifically, self-employment was found to have a greater protective effective against homicide while civic engagement and homeownership had greater protective effects against aggravated assault. The paper is concluded with a discussion of theoretical implications, limitations of the current project, and avenues for future research

Structural plumage coloration, male body size, and condition in the blue-black grassquit

In birds, the colors ultraviolet, blue, and green originate from feather microstructure rather than pigmentation. Structural plumage coloration may be maintained by sexual selection, yet there exists only limited evidence that structural colors can honestly signal individual quality. In this study, I found considerable individual variation in the blue-black to ultraviolet coloration of the wing coverts and rump of male Blue-black Grassquits (Volatinia jacarina), thereby revealing the potential for sexual selection on structural plumage coloration in this species. I used a principal components analysis (PCA) of four color characteristics to combine reflectance data into a single color score. Birds with high color scores have brighter, more intensely colored, and more saturated blue-black feathers. There was a significant positive relationship between color scores for both body regions and male condition. There was also a positive trend between the color score of the rump region and male body size. These results support recent findings that structural plumage coloration is condition-dependent, and this type of coloration may be an honest signal of male quality in the Blue-black Grassquit. Coloración Estructural del Plumaje, Tamaño Corporal y Condición Física en Machos de Volatinia jacarina Resumen. En las aves, los colores ultravioleta, azul y verde están dados por la microestructura de las plumas y no por la pigmentación. La coloración estructural del plumaje puede ser mantenida por selección sexual, aunque existe poca evidencia que indique que los colores estructurales son un indicador confiable de la calidad de un individuo. En este estudio encontré variación individual considerable en la coloración negro-azulada a ultravioleta de las cobertoras alares y la rabadilla de machos de Volatinia jacarina, revelando que la coloración estructural del plumaje en esta especie podría estar sujeta a selección sexual. Utilicé un análisis de componentes principales (PCA) de cuatro características de color para combinar datos de reflectancia en un solo valor de color. Las aves con altos valores de color tienen plumas más brillantes e intensamente coloreadas y más saturadas de color negro-azulado. Existió una relación positiva significativa entre los valores de color para ambas regiones del cuerpo y la condición física de los machos. También hubo una tendencia positiva entre el valor del color de la región de la rabadilla y el tamaño corporal de los machos. Estos resultados apoyan descubrimientos recientes que demuestran que la coloración estructural del plumaje depende de la condición física, y que este tipo de coloración puede ser una señal confiable de la calidad de los machos de V. jacarina

Educational Perspectives: Integrating a Student Post-Stroke Clinic within a First-Year Occupational Therapy Kinesiology Course

ABSTRACTPurpose: In many occupational therapy graduate programs, student experiences with actual patient evaluation and intervention typically occur following several semesters of didactic instruction. We explored the impact of an early immersive and reflective hands-on patient experience on student learning and clinical skill development. Method: Following participation in five task-specific occupational therapy clinical sessions that were embedded into an applied kinesiology course, students performed reflections on the experience. These reflections included thoughts on kinesiology course content and clinical skill development through patient sessions over the semester. Results: A qualitative thematic analysis of student reflections was conducted. Findings reflected themes of improvement in observation skills, intervention abilities and communication. Conclusion: Early reflective and immersive clinical experiences may be helpful in the reinforcement of course content and in the development of clinical skills of occupational therapy graduate students prior to full intervention content exposure

Civic Community Theory and Rates of Violence: A Review of Literature on an Emergent Theoretical Perspective

Civic community theory has emerged in the last 10 years as a middle range theory to explain community variation in rates of crime. It has proven to be particularly powerful for explaining variations in violent crime across rural communities in the U.S. This essay provides a review of the available published literature testing components of the theory. The three main conceptual dimensions of the civic community thesis are outlined, and the nature of the empirical evidence is evaluated. The essay concludes with several suggestions for future research

Study of a Long Baseline nu_tau Appearance Neutrino Oscillation Experiment in the Quasi-Elastic Regime

We present a study for a design of a long baseline nu_mu to nu_tau appearance experiment to probe the high sin^2(2theta) and low Delta m^2 region relevant to explain the atmospheric neutrino anomaly. The experiment relies on a good identification of quasi-elastic interactions, which is a clean topology that has an important contribution in the lowest Delta m^2 part of the region probed. The detector we studied is a fine grained liquid scintillator detector of 15 kilotons, optimized to detect electrons from tau -> e bar(nu_e) nu_tau decays, while rejecting backgrounds from pi^0 in nu_mu interactions and electrons from the nu_e beam contamination. As a reference, the proposed nu_mu neutrino beam from CERN to Gran Sasso was used.Comment: 17 page

Comparative analysis of morphological and morphometrical characters in six isolates of Pratylenchus vulnus Allen & Jensen, 1951 (Nemata : Tylenchida)

Six populations de #Pratylenchus vulnus$ Allen & Jensen, 1951 provenant d'Europe et d'Amérique ont été analysées du point de vue morphologique et morphométrique. Certaines différences ont été observées pour quelques caractères morphologiques (structure du sac post-vulvaire, forme de la spermathèque, largeur des champs latéraux). Par contre, des différences significatives concernant tous les caractères morphométriques (excepté le rapport "m") ont été constatées entre les populations. Une analyse de corrélation canonique montre que les relations entre populations pourraient être fonction de leur origine géographique et/ou de leur plante hôte. (Résumé d'auteur