Joint Estimation of Intersecting Context Tree Models

We study a problem of model selection for data produced by two different context tree sources. Motivated by linguistic questions, we consider the case where the probabilistic context trees corresponding to the two sources are finite and share many of their contexts. In order to understand the differences between the two sources, it is important to identify which contexts and which transition probabilities are specific to each source. We consider a class of probabilistic context tree models with three types of contexts: those which appear in one, the other, or both sources. We use a BIC penalized maximum likelihood procedure that jointly estimates the two sources. We propose a new algorithm which efficiently computes the estimated context trees. We prove that the procedure is strongly consistent. We also present a simulation study showing the practical advantage of our procedure over a procedure that works separately on each data set.     

The Well-Being of the Canadian Arctic Inuit: The Relevant Weight of Economy in the Happiness Equations

Which of the three dimensions of Allardt’s model, “having, loving, and being”, best predicts the incidence of subjective feeling of well-being among the Canadian Arctic Inuit adults? To answer this question, two logistic regression equations have been constructed, one based on a negative assessment of well-being (feeling of despair), and the other on a positive assessment (satisfaction with life in the community). Each of them took first the form of a global model, and then of three scale models, one for each dimension of the Allardt’s model. The equations are likely to be more effective for predicting the incidence of Inuit’s feeling of satisfaction than for anticipating their feeling of despair. Furthermore, the “being” scale model is the one that will have contributed most to the predictive performance of the global model. In other words, what the Inuit “ARE” contributes more to the incidence of their satisfaction with life than what they “HAVE” or what they “LOVE”.     

Second Unions Now More Stable than First? A Comparison of Separation Risks by Union Order in France

The frequency of union dissolutions increased sharply over the past 40 years in Western Europe and North America, resulting in a rapid growth in the number of persons living with a second partner. In studies of the 1980s, primarily conducted within the context of marriage, second partnerships were generally found to be less stable than first unions, but more recent studies provide more conflicting evidence. Taking the example of France, we study whether the relationship between first and second union stability indeed reversed between the 1970s and the 2000s, and how union and individual characteristics contributed to changes over time. The analysis presented here is based on the French Generations and Gender Survey (2005). The article first provides an overview of the differences in marriage, childbearing and breakup behaviours in first and second unions. Second, a piecewise linear model for repeated events is used to compare women’s dissolution risks in first and second unions. The results show that over time, the higher instability of second compared to first unions disappeared. Further, women in second unions adopted unmarried cohabitation as a living arrangement more often across the whole period and were more likely to have stepchildren, which was associated with less stable unions. Taking into account this diversity of family situations, i.e. controlling for family form and children, second unions were more stable than first unions, even during the past. At both union orders, marriage breakup risks tended to stabilise despite a continuing increase in the prevalence of separation, which suggests that cohabitation increasingly acts as a filter for marriage.     

Response of wild bee communities to beekeeping,urbanization, and flower availability

Urban Ecosystems - Wild bees provide pollination services and are currently declining at the global scale. A potential cause for this decline is competitive interactions with domestic honey bees....     

Daily rhythm of salivary IL-1ß, cortisol and melatonin in day and night workers

Shiftwork-induced sleep deprivation and circadian disruption probably leads to an increase in the production of cytokines and dysregulation of innate immune system, respectively. This project aims evaluating changes in salivary IL-1 beta, cortisol, and melatonin in night workers. Method. Two day and three night healthy workers participated in this study. Sleep was evaluated by actimetry and activity protocols. Saliva was collected at waking and bedtime the last workday and the following two days-off and was analyzed by ELISA. Results. Neither sleep duration nor efficiency showed any association with salivary IL-1beta. IL-1beta levels were higher at waking than at bedtime during working days for all workers, but only one day and one night-worker maintained this pattern and hormone rhythms during days off. For this night worker, melatonin levels were shifted to daytime. A second one presented clear alterations in IL-1beta and hormone rhythms on days-off. Conclusions. Our preliminary results suggest that night work can disturb the variation pattern of salivary IL-1beta. No association of this variation with sleep was observed. It seems that disruption in hormone rhythms interfere with salivary IL-1beta production. IL- 1beta production pattern seems to be maintained when rhythms are present, in spite of a shift in melatonin secretion.     

Humor and Identity on Twitter: #muslimcandyheartrejects as a Digital Space for Identity Construction

Through examining the hashtag #muslimcandyheartrejects, a one-time, short-term, joke hashtag used on Twitter among a group of Muslim tweeters in 2012, we argue that members of Muslim digital diaspora communities use social media to construct and reinforce a Muslim diaspora identity. The architecture of Twitter provides the structure for these engagements, while humor serves meaning-making, cohesion building, and tension-relief functions within the conversation. The conversation itself combines a variety of topics to both describe Muslim identity in diaspora and to critique both Muslim community practices and conditions for Muslims in non-Muslim countries.     

Bounds for the Expected Time to Extinction and the Probability of Extinction in the Galton-Watson Process

Upper bounds for the expected time to extinction in the Galton-Watson process are obtained. We also found upper and lower bounds for the probability of extinction of this process. These bounds improve some bounds previously obtained by other authors.     

Negative Dependence in Sampling

Abstract. The strong Rayleigh property is a new and robust negative dependence property that implies negative association; in fact it implies conditional negative association closed under external fields (CNA+). Suppose that and are two families of 0‐1 random variables that satisfy the strong Rayleigh property and let . We show that {Z_i} conditioned on is also strongly Rayleigh; this turns out to be an easy consequence of the results on preservation of stability of polynomials of Borcea & Brändén (Invent. Math., 177, 2009, 521–569). This entails that a number of important π ps sampling algorithms, including Sampford sampling and Pareto sampling, are CNA+. As a consequence, statistics based on such samples automatically satisfy a version of the Central Limit Theorem for triangular arrays.     

The worldwide maritime network of container shipping: spatial structure and regional dynamics

Port and maritime studies dealing with containerization have observed traffic concentration and dispersion throughout the world. Globalization, intermodal transportation, and technological revolutions in the shipping industry have resulted in both network extension and rationalization. However, lack of precise data on inter‐port relations prevent the application of wider network theories to global maritime container networks, which are often examined through case studies of specific firms or regions. In this article, we present an analysis of the global liner shipping network in 1996 and 2006, a period of rapid change in port hierarchies and liner service configurations. While we refer to literature on port system development, shipping networks, and port selection, the article is one of the only analyses of the properties of the global container shipping network. We analyse the relative position of ports in the global network through indicators of centrality. The results reveal a certain level of robustness in the global shipping network. While transhipment hub flows and gateway flows might slightly shift among nodes in the network, the network properties remain rather stable in terms of the main nodes polarizing the network and the overall structure of the system. In addition, mapping the changing centrality of ports confirms the impacts of global trade and logistics shifts on the port hierarchy and indicates that changes are predominantly geographic.     

WebStress: A web interface to explore a multidatabase bibliographic corpus on occupational stress

A bibliographic study on a multidisciplinary subject, such as occupational stress, requires a multidatabase query facility. Given this, we searched eight databases belonging to different fields (medicine, psychology, etc.) and from different countries. Thus, more than 26000 references on occupational stress were gathered. A bibliographic corpus of this sort is unusable because of the heterogeneous format of the records and the number of duplicate entries. Considering the limitations of commercial programs, we have developed a system, called WebStress, for reformatting the data and removing duplicates. The huge number of references and the research needs of updating and searching have necessitated the addition of several other functions to WebStress. Therefore WebStress comprises a web interface that makes it possible to search the corpus with advanced features (using clustering, a specialized thesaurus on stress and Boolean queries). In addition to the usual bibliographic queries on a specific database such as Medline, WebStress provides bibliometric analysis of the corpus, which might contribute to a detailed analysis on occupational stress in order to highlight the networks of researchers and to find the main topics studied in this area. WebStress is not yet available to researchers in general. It is being further developed, and also permission needs to be obtained from the eight commercial bibliographic databases that it consults.