Comparisons of coherent systems with non-identically distributed components

The signature-based mixture representations for coherent systems are a good way to obtain distribution-free comparisons of systems. Unfortunately, these representations only hold for systems whose component lifetimes are independent and identically distributed (IID) or exchangeable (i.e., their joint distribution is invariant under permutations). In this paper we obtain comparison results for generalized mixtures, that is, for reliability functions that can be written as linear combinations of some baseline reliability functions with positive and negative coefficients. These results are based on some concepts in Graph Theory. We apply these results to obtain new comparison results for coherent systems without the IID or exchangeability assumptions by using their generalized mixture representations based on the minimal path sets.     

Pattern Matching

An important subtask of the pattern discovery process is pattern matching, where the pattern sought is already known and we want to determine how often and where it occurs in a sequence. In this paper we review the most practical techniques to find patterns of different kinds. We show how regular expressions can be searched for with general techniques, and how simpler patterns can be dealt with more simply and efficiently. We consider exact as well as approximate pattern matching. Also we cover both sequential searching, where the sequence cannot be preprocessed, and indexed searching, where we have a data structure built over the sequence to speed up the search.     

Subjective well‐being: what do adolescents say?

The aim of this paper is to analyse how 10‐ to 15‐year‐old adolescents define their own perceptions of well‐being and the factors influencing it at their age. Ten focus groups were organized, two from each age group. One group for each age included the students with the lowest scores in subjective well‐being (SWB) and the other included those with the highest, according to their responses to previously administered psychometric scales. The views of the participating adolescents were explored by means of a content analysis. In general, the children mentioned both positive and negative elements of participating in defining what constitutes well‐being. According to these children, well‐being is related to both affects and attitudes, relations with family and friends being key factors in it. Differences in the information provided reveal some variations according to age and SWB score. Children scoring lower in SWB tend to refer more to relationships with friends and basic needs covered, whereas those scoring higher tend to refer more to family relationships and not having problems. The results of this research can contribute to both social policy design and appraisal as they provide an in‐depth understanding of how SWB works at these ages.     

The Effect of Absorptive Capacity on Innovativeness: Context and Information Systems Capability as Catalysts

The purpose of this study is to examine the relationship between absorptive capacity and company innovativeness and to identify potential contexts and capabilities that can act as catalysts for these relationships. We also examine the relationship between absorptive capacity and the existence and enhancement of innovativeness. These relationships are examined through an empirical investigation of 286 large Spanish companies. Our results show that absorptive capacity is an important dynamic determinant for developing a company's innovativeness. Moreover, this relationship is best explained by two related constructs. First, the company's unlearning context is a crucial determinant for both potential capacity and realized absorptive capacity. Second, the results also indicate a tangible means for managers to enhance their absorptive capacity through information systems capabilities.     

Characterizations through reliability measures from weighted distributions

In this paper we obtain general characterizations of probability distributions from relationships between failure rate and mean residual life from the origin distribution and associated weighted distribution. Our characterization properties extend particular results given by Gupta and Keating (1986), Jain et al. (1989) and Asadi (1998). Using the theoretical results we obtain characterizations of some usual distributions. Received: December 7, 1998; revised version: May 10, 2000     

Distorted Lorenz curves: models and comparisons

The economic literature contains many parametric models for the Lorenz curve. A number of these models can be obtained by distorting an original Lorenz curve $L$ by a function $h$ , giving rise to a distorted Lorenz curve ${\widetilde{L}}=h\circ L$ . In this paper, we study, in a unified framework, this family of curves. First, we explore the role of these curves in the context of the axiomatic structure of Aaberge (2001) for orderings on the set of Lorenz curves. Then, we describe some particular models and investigate how changes in the parameters in the baseline Lorenz curve $L$ affect the transformed curve ${\widetilde{L}}$ . Our results are stated in terms of preservation of some stochastic orders between two Lorenz curves when both are distorted by a common function.     

How Good Are Networks for Migrant Job Seekers? Ethnographic Evidence from North Carolina Farm Labor* Camps

Migrant farmworker networks are vital components in their job seeking and underemployment minimization strategies. Yet, farmworker cultural, physical, and institutional isolation along with the itinerant and clandestine features of farmwork have become major obstacles in the development of robust lateral communitywide network ties that would otherwise favor reciprocity and resource sharing. Thus, contrary to the positive social capital assumption, we argue that the paucity and fragmented features of farmworkers’ lateral ties have increased their vulnerability and locked them in exploitative relationships in a hostile social environment that makes impractical or impossible the formation of alternative ties. Our study is based on participant observation through a 6‐week stay in three North Carolina farm labor camps. On‐site evidence shows that the two larger groups of solitary male farmworkers and farmworking families break up into smaller groups, each group in pursuit of its own short‐term goals. We conclude that, even though farmworker networks help them to find and ensure temporary jobs, their inability to use the networks to share resources is ultimately detrimental for participants’ long‐term socioeconomic prospects.     

Bestiality: An Overview and Analytic Discussion

Individuals who experience sexual and emotional attractions to animals are widely considered deviant in American society. Such a condition is frequently referred to as bestiality and zoophilia, which in fact describe two separate types of sexual behaviors. A multitude of studies have uncovered a range of prevalence rates across different demographic groups, which may vary due to the terminology and the type of data collection methods utilized. Dogs and horses are consistently chosen as the preferred animal to engage in sexual activities by humans, while male animals have been presented as the heavily favored sex of animal. It is questionable whether one's sexual orientation corresponds with the preference of the sex of the animal. Those engaged in human–animal sexual contacts vary in their reasoning behind their sexual behavior with animals, which are generally environmentally or belief based, and reinforce certain myths. Since the development of the Internet not only has it promoted an enhanced research perspective of the sexual behaviors of bestialists and zoophiles, but they have also found an environment populated by like‐minded individuals with similar sexual behaviors/interests.