Dynamic reliability models with conditional proportional hazards

A dynamic approach to the stochastic modelling of reliability systems is further explored. This modelling approach is particularly appropriate for load-sharing, software reliability, and multivariate failure-time models, where component failure characteristics are affected by their degree of use, amount of load, or extent of stresses experienced. This approach incorporates the intuitive notion that when a set of components in a coherent system fail at a certain time, there is a jump from one structure function to another which governs the residual lifetimes of the remaining functioning components, and since the component lifetimes are intrinsically affected by the structure function which they constitute, then at such a failure time there should also be a jump in the stochastic structure of the lifetimes of the remaining components. For such dynamically-modelled systems, the stochastic characteristics of their jump times are studied. These properties of the jump times allow us to obtain the properties of the lifetime of the system. In particular, for a Markov dynamic model, specific expressions for the exact distribution functions of the jump times are obtained for a general coherent system, a parallel system, and a series-parallel system. We derive a new family of distribution functions which describes the distributions of the jump times for a dynamically-modelled system.     

Ethnography, Cultural Change and Local Power

The author argues that despite the declaration for the end of ethnography by some North American scholars, ethnography is precisely what is needed for a more nuanced and complex understanding of cultural change. Using snippets of ethnographic observation from the Mexican state of Michoacan, the argument is made that neither "modernization" nor "globalization" are imposed from above, but are woven together with local processes to create institutions and practices which synthesize both the "traditional" and the "modern" in previously unimagined ways. Local people and processes are thus conceived of as dynamic partners in cultural change rather than passive subjects. Ethnography, then, is a fruitful means for uncovering how and the extent to which this is so.     

The State of Research in Latino Academic Attainment

In this essay, I present an interdisciplinary examination of the state of research in Latino education, addressing not only the cultural forces influencing Latinos’ educational attainment, but also the structural conditions faced by them—as a racialized minority group—throughout their schooling and that have a cumulative effect on their academic attainment. Overall, I suggest that by engaging in a critical review of the literature on Latinos’ educational attainment, the reader will acknowledge that the racially driven hierarchical structural arrangements are highly responsible for the patterns observed.     

Self‐Construal,Career Decision Self‐Efficacy,and Perceived Barriers Predict Mexican American Women's Life Satisfaction

This study used the social cognitive theory of well‐being (SCTW; Lent, 2004 ) to examine the role of career decision self‐efficacy (CDSE), perceived educational barriers, and independent self‐construal on the life satisfaction of 176 Mexican American college women. A 3‐step hierarchical regression analysis indicated that independent self‐construal, CDSE, and fewer perceived educational barriers significantly predicted greater life satisfaction among Mexican American college women above and beyond the influence of socioeconomic status and generational status. These findings are consistent with SCTW and highlight the need for counselors and researchers to be aware of the role that self‐construal, CDSE, and perceived educational barriers can have on Mexican American women's life satisfaction. Implications for practice at the secondary‐school and university levels are discussed.     

The Slaughtered and the Survivors: Collaboration Between Social Economy Organizations as a Key to Success in Times of Financial Crisis

The objective of this study is to analyze the aspects that allowed a critical part of Social Economy Organizations (SEOs) to survive a recession period, especially participation in collaborative networks. The financial stress of an SEO will depend on the resources and capabilities available to the organization. To analyze the financial stress of Spanish SEOs, we defined a sample of 714 SEOs. Approximately half of these organizations suffered from financial stress in the analyzed period (2009–2012). The results obtained in this study reveal the existence of three factors that distinguish organizations under financial stress: (a) a high dependence on government funding; (b) changes in the relationship between staff and volunteers; and (c) a lack of access to markets. The combination of these three elements results in an unsustainable situation for the organization. The development of a collaborative profile increases the SEO’s probability of surviving the adverse manifestations of its environment.     

A Stochastic Model to Assess the Effect of Meat Inspection Practices on the Contamination of the Pig Carcasses

The objective of meat inspection is to promote animal and public health by preventing, detecting, and controlling hazards originating from animals. With the improvements of sanitary level in pig herds, the hazards profile has shifted and the inspection procedures no longer target major foodborne pathogens (i.e., not risk based). Additionally, carcass manipulations performed when searching for macroscopic lesions can lead to cross‐contamination. We therefore developed a stochastic model to quantitatively describe cross‐contamination when consecutive carcasses are submitted to classic inspection procedures. The microbial hazard used to illustrate the model was Salmonella, the data set was obtained from Brazilian slaughterhouses, and some simplifying assumptions were made. The model predicted that due to cross‐contamination during inspection, the prevalence of contaminated carcass surfaces increased from 1.2% to 95.7%, whereas the mean contamination on contaminated surfaces decreased from 1 logCFU/cm² to ?0.87 logCFU/cm², and the standard deviations decreased from 0.65 to 0.19. These results are explained by the fact that, due to carcass manipulations with hands, knives, and hooks, including the cutting of contaminated lymph nodes, Salmonella is transferred to previously uncontaminated carcasses, but in small quantities. These small quantities can easily go undetected during sampling. Sensitivity analyses gave insight into the model performance and showed that the touching and cutting of lymph nodes during inspection can be an important source of carcass contamination. The model can serve as a tool to support discussions on the modernization of pig carcass inspection.     

Utilization of Mixed Distributions in the Calculation of Polarization: The Case of Spain

Social Indicators Research - This study analyzes the evolution of salary polarization in the Spanish labor market. The paper proposes the use of mixed distributions to examine the consequences of...