Caloric restriction minimizes aging effects on the femoral medial condyle

This study aimed to analyze the effects of caloric restriction on aged femoral articular cartilage of Wistar rats. Three groups of eight animals each were considered: young (YC) and old (OC) control groups fed with a normal diet and old caloric restriction group (OCR) composed of 18-month-old animals fed with a 31% less caloric diet from 6-months of age. Articular cartilage was studied through morphometry and immunohistochemistry. Body mass was 12% less in the OCR group than in the OC group. The articular cartilage from OC rats show thinner medial condyles, fewer chondrocytes, smaller chondrocytes nuclear volume and, in both condyles, a predominance of collagen type II and less collagen density compared to both YC and OCR groups (p?p?相似文献   

Application of a non-homogeneous Markov chain with seasonal transition probabilities to ozone data

In this work, we assume that the sequence recording whether or not an ozone exceedance of an environmental threshold has occurred in a given day is ruled by a non-homogeneous Markov chain of order one. In order to account for the possible presence of cycles in the empirical transition probabilities, a parametric form incorporating seasonal components is considered. Results show that even though some covariates (namely, relative humidity and temperature) are not included explicitly in the model, their influence is captured in the behavior of the transition probabilities. Parameters are estimated using the Bayesian point of view via Markov chain Monte Carlo algorithms. The model is applied to ozone data obtained from the monitoring network of Mexico City, Mexico. An analysis of how the methodology could be used as an aid in the decision-making is also given.     

Development and Psychometric Properties of the Classroom Peer Context Questionnaire

Children's view on the peer context in their classroom may differ from that of other informants, but no measure systematically examines children's own view. Therefore, we developed the Classroom Peer Context Questionnaire (CPCQ) and evaluated its reliability, validity, and stability in two studies. In Study 1, 464 children (M_age = 10.8 years, 53.2% girls) from 18 Grade 5 classrooms participated in 2 waves of data collection. In Study 2, 1538 children (M_age = 10.6 years, 47.2% girls) from 59 Grade 5 classrooms participated in 3 waves of data collection. Exploratory factor analyses in Study 1 revealed 5 dimensions labeled comfort, cooperation, conflict, cohesion, and isolation. Confirmatory factor analyses in Study 2 supported these 5 dimensions. Study 2 also demonstrated good reliability, validity, and stability for each dimension. Researchers and professionals in schools may use the CPCQ to obtain reliable and quick information on how children perceive the peer context in their classroom.     

The role of privacy concerns in the sharing economy

Internet-mediated sharing is growing quickly. Millions of users around the world share personal services and possessions with others ? often complete strangers. Shared goods can amount to substantial financial and immaterial value. Despite this, little research has investigated privacy in the sharing economy. To fill this gap, we examine the sharing–privacy nexus by exploring the privacy threats associated with Internet-mediated sharing. Given the popularity of sharing services, users seem quite willing to share goods and services despite the compounded informational and physical privacy threats associated with such sharing. We develop and test a framework for analyzing the effect of privacy concerns on sharing that considers institutional and social privacy threats, trust and social-hedonic as well as monetary motives.     

Sí, Yo Puedo Curricula and Police Departments: Educating Immigrant Latinas

ABSTRACT

Immigrant Latinas experiencing incidences of interpersonal violence require services from police departments. In a mixed-methods study using a culturally specific curriculum, Si, Yo Puedo, designed to foster self-esteem and provide education on interpersonal violence and healthy relationships, two groups (n = 14) were conducted in 2015 at a precinct in a midwestern state. This group-format curriculum is a 2-hour, topic-specific educational program, conducted in Spanish, offered in 11 weeks. Participants reported an increase in self-esteem and knowledge of interpersonal violence after completing the program. Findings implicate this curriculum as a suitable service tool for police departments working with immigrant Latinas.     

A queueing model to study the occurrence and duration of ozone exceedances in Mexico City

It is well known that long-term exposure to high levels of pollution is hazardous to human health. Therefore, it is important to study and understand the behavior of pollutants in general. In this work, we study the occurrence of a pollutant concentration's surpassing a given threshold (an exceedance) as well as the length of time that the concentration stays above it. A general N(t)/D/1 queueing model is considered to jointly analyze those problems. A non-homogeneous Poisson process is used to model the arrivals of clusters of exceedances. Geometric and generalized negative binomial distributions are used to model the amount of time (cluster size) that the pollutant concentration stays above the threshold. A mixture model is also used for the cluster size distribution. The rate function of the non-homogeneous Poisson process is assumed to be of either the Weibull or the Musa–Okumoto type. The selection of the model that best fits the data is performed using the Bayes discrimination method and the sum of absolute differences as well as using a graphical criterion. Results are applied to the daily maximum ozone measurements provided by the monitoring network of the Metropolitan Area of Mexico City.     

Risk evaluation and exposure control of mineral dust containing free crystalline silica: a study case at a quarry in the Recife Metropolitan Area

During the production of aggregates at quarry sites, elevated quantities of micro-particulate mineral dust are produced in all stages of the process. This dust contains appreciable amounts of free crystalline silica in a variety of forms which, if maintained suspended in the air in the work environment, expose the workers to the risk of developing occupational silicosis, which causes reduced ability to work and potential shortening of lifespan. This study was conducted to qualitatively and quantitatively evaluate workers' exposure to mineral dust containing free crystalline silica at a midsized quarry in the Recife metropolitan area, in the State of Pernambuco. It involved evaluation of the industrial process, collection and analysis of representative dust samples, and interviews with the management team of the company with the intent to assess the compliance of the company with Regulatory Standard (NR) 22--Occupational safety and health in mining. In order to assist the company in managing risks related to dust exposure, three protocols were developed, implemented and made available, the first based on NR 22, from which the company was also given an economic safety indicator, the second based on the recommendations and requirements of Fundacentro to implement a Respiratory Protection Program and, finally, an assessment protocol with respect to the guidelines of the International Labor Organization to implement a health and safety management system. This study also showed the inadequacy of the formula for calculating tolerance limits in Brazilian legislation when compared with the more strict internationally accepted control parameters. From the laboratory results, unhealthy conditions at the quarry site were confirmed and technical and administrative measures were suggested to reduce and control dust exposure at acceptable levels, such as the implementation of an occupational health and safety management system, integrated with other management systems. From these assessments it is hoped that the proposals can assist the company in developing mechanisms for management and control of dust exposure risks that may improve environmental quality and the well-being of workers.