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. 相似文献
Previous empirical literature on the relation between intergenerational transfer of assets and services has mostly focused on contemporary exchanges. By contrast, we provide novel evidence showing that parents who helped their adult children in the past are rewarded by higher chances of receiving informal care later in life. To this end we use Italian data containing precise retrospective information about the help with housing that couples received from their parents when they got married, such as a real estate donation or down payment. Our estimates show that this type of past help is positively associated with the current provision of informal care to the parents. This result is robust to controlling for a large set of individual and family characteristics and is only partially due to increased geographical proximity. We suggest that this finding can be explained by mixed self-interest motives, related to theories based on either bilateral exchange or the presence of a third generation (grandchildren), such as the demonstration effect model or the family constitution model. 相似文献
As known, the least-squares estimator of the slope of a univariate linear model sets to zero the covariance between the regression residuals and the values of the explanatory variable. To prevent the estimation process from being influenced by outliers, which can be theoretically modelled by a heavy-tailed distribution for the error term, one can substitute covariance with some robust measures of association, for example Kendall's tau in the popular Theil–Sen estimator. In a scarcely known Italian paper, Cifarelli [(1978), ‘La Stima del Coefficiente di Regressione Mediante l'Indice di Cograduazione di Gini’, Rivista di matematica per le scienze economiche e sociali, 1, 7–38. A translation into English is available at http://arxiv.org/abs/1411.4809 and will appear in Decisions in Economics and Finance] shows that a gain of efficiency can be obtained by using Gini's cograduation index instead of Kendall's tau. This paper introduces a new estimator, derived from another association measure recently proposed. Such a measure is strongly related to Gini's cograduation index, as they are both built to vanish in the general framework of indifference. The newly proposed estimator is shown to be unbiased and asymptotically normally distributed. Moreover, all considered estimators are compared via their asymptotic relative efficiency and a small simulation study. Finally, some indications about the performance of the considered estimators in the presence of contaminated normal data are provided. 相似文献
Increasingly, mental health and medical professionals have been asked to assess claims of psychological harm arising from harassment at the workplace, or "mobbing." This study assessed the personality and psychopathological profiles of 146 individuals exposed to mobbing using validity, clinical, and content scales of the Minnesota Multiphasic Personality Inventory 2. Profiles and factor analyses were obtained. Two major dimensions emerged among those exposed to mobbing: (a) depressed mood, difficulty in making decisions, change-related anguish, and passive-aggressive traits (b) somatic symptoms, and need for attention and affection. This cross-sectional pilot study provides evidence that personality profiles of mobbing victims and psychological damage resulting from mobbing may be evaluated using standardized assessments, though a longitudinal study is needed to delineate cause-and-effect relationships. 相似文献
This article reflects on the importance of the relations between state and society in policy-making in the area of public
health. Several studies in various sectors such as health, education, and social services have made similar observations on
organizational dynamics and the institutionalization of different models of partnerships or contracts, often based on the
analytical model of three sectors. Individuals and their networks of relationships, however, remain an almost unexplored dimension
in these types of research. Against this backdrop, this study seeks to analyze the movement of HIV/AIDS activists to governmental
organizations working in this same field. The analysis raises questions concerning the forms of individual and institutional
learning that help to maintain the distinct character of innovation of the Brazilian policy. Professionals who cross the borders
hold a different profile once they have accumulated experience working with grassroots and local NGOs, and have also had the
chance to be trained and enhance their technical and managerial capacities, since the government has supported NGOs for a
long period. When combined, these experiences allow them to maintain relationships with social movements and give them the
ability to navigate through the government bureaucracy and handle technical information about fighting AIDS epidemics, making
it possible for them to negotiate strategic collaborations reflecting the interests of different groups. Hence, they constantly
reflect on the differences between government and social spaces, and keep questioning and modifying their roles in the light
of potential and existing complementarities. 相似文献
Gravediggers have death as object of their work. Their activities are painful, physically and mental demanding, as well as unhealthy. Literature is scarce about this theme. The aim of this study is to evaluate gravediggers' work activities and health consequences. The methodological frame which guided this study was Dejours' psychic suffering and its association with the psychodynamic aspects of work. Data collection took place in April-May 2011 in one public and one private cemetery of S?o Paulo, Brazil. Four male workers, aged between 45 to 60 years old were interviewed. Their work activities were observed during a workday. Participants reported their life dreams, defense mechanisms and frustration. The discourse of gravediggers showed serious problems associated to physical and mental demands, public invisibility and/ or social devaluation of work. The most important physical symptom was body pain. In spite this is a preliminary study, it was possible to raise a number of work stressors and health outcomes of gravediggers, an "invisible" worker of our society. 相似文献
This article analyses intercultural education outcomes produced in the setting of teaching Italian as a second language (ISL) in an Italian school. Intercultural education is produced in interactions which are based on specific cultural presuppositions, i.e. expectations regarding learning, role hierarchy and evaluation of student performances. Sixteen hours of interactions associated with ISL teaching in a multicultural classroom were audiotaped, transcribed and analysed. The analysis highlights three ways in which cultural diversity becomes meaningful. First, cultural diversity is constructed as one task of learning. Second, cultural diversity is constructed as conflictive interaction. Third, cultural diversity is constructed as a point of departure for positive school performance. These three ways of giving meaning to cultural diversity reveal a prevailing ethnocentric form of ISL teaching, as a consequence of educational presuppositions which do not take the difficulties of intercultural communication seriously. Recently, ‘dialogue’ has been invoked to address ethnocentrism; however, the conditions of effective intercultural dialogue are uncertain.
Questo articolo analizza l’educazione interculturale prodotta nell’insegnamento dell’italiano come seconda lingua (ISL) in una scuola italiana. L’educazione interculturale è realizzata in interazioni che sono basate su specifici presupposti culturali, che sono aspettative di apprendimento, di gerarchie di ruolo e di prestazioni degli studenti. L’educazione interculturale si occupa del problema della diversità culturale, basata su presupposti culturali diversi che emergono nella comunicazione. Sono state audioregistrate, trascritte e analizzate 16 ore di interazione durante l’insegnamento di ISL in una classe multiculturale: l’analisi ha evidenziato tre modi in cui la diversità culturale è resa significativa. La diversità culturale è costruita anzitutto come compito di apprendimento, in secondo luogo come interazione conflittuale, infine come punto di partenza per conseguire una prestazione scolastica positiva. Questi tre modi di costruire la diversità culturale rivelano una forma prevalente di tipo etnocentrico per l’insegnamento ISL, che è una conseguenza di presupposti educativi che non permettono di prendere seriamente le difficoltà della comunicazione interculturale. Recentemente, si è proposto di usare il ‘dialogo’ per superare l’etnocentrismo; tuttavia c’è incertezza sulle condizioni di un dialogo interculturale efficace. 相似文献
Cooperative relationships between groups are difficult because of the high human capability to differentiate between in-group vs. out-group members. This obstacle exists even when the groups can obtain benefits for themselves from cooperation with other groups (rational cooperation). Based on an interactionist approach, the authors propose that personal (individual differences) and situational (conflicts) factors contribute to rational intergroup cooperation. The authors conducted a preliminary correlational study (Study 1) and an experimental investigation (Study 2). In Study 1, the authors examined, with 105 participants, the psychometric properties of the Spanish version of the Rational–Experiential Inventory (REI), measuring individual differences in information processing. In Study 2, the authors conducted an experimental investigation with 141 participants, testing the role of individual differences and conflict in intergroup rational cooperation. Findings of Study 1 showed that the scale has adequate psychometric properties. Results of Study 2 confirmed that the existence of both manipulated and perceived intergroup conflict reduces the magnitudes of the relationships between rational ability and rational cooperation. In addition, perceived intergroup conflict increased the magnitude of the links from experiential ability and experimental engagement to rational cooperation. Both individual differences and previous conflict have a role in predicting rational intergroup cooperation. According to the interactionist approach, personal and situational factors should be considered in the understanding of intergroup relationships. 相似文献