The Current Duration Approach to Estimating Time to Pregnancy

Abstract. Time‐to‐pregnancy (TTP) is the duration from the time a couple starts trying to become pregnant until they succeed. It is considered one of the most direct methods to measure natural fecundity in humans. Statistical tools for designing and analysing time to pregnancy studies belong to survival analysis, but several features require special attention. Prospective designs are difficult to carry out and retrospective (pregnancy‐based) designs, being widely used in this area, do not allow efficiently including couples remaining childless. A third possible design starts from a cross‐sectional sample of couples currently trying to become pregnant, using current duration (backward recurrence time) as basis for the estimation of TTP. Regression analysis is then most conveniently carried out in the accelerated failure time model. This paper surveys some practical and technical‐statistical issues in implementing this approach in a large telephone‐based survey, the Epidemiological Observatory of Fecundity in France (Obseff).     

Different Eastern European Countries at Different Crossroads

This paper takes an initial step toward a better understanding of the complex set of pressing problems that need to be addressed by the Eastern European nonprofit sectors and their supporters in the near future. It gives an overview of the main challenges and claims that different nonprofit sectors of the region are at different crossroads. It identifies a general policy crisis that is fueled by the lack of a comprehensive knowledge of the sector and clear political intentions of cooperating with it. In addition, the dependence on foreign funding may result in a sustainability crisis in several Eastern European countries. In the most developed part of the region, the main elements of the present crisis are the fiscal, economic, effectiveness, identity, and legitimacy problems, which have something in common with the challenges facing the much more mature nonprofit sectors of the developed world.     

The cosmopolitan elite in Germany: transnationalism and postmaterialism

In this article, we investigate cosmopolitan attitudes among the people often considered the most cosmopolitan – the elite. Studying the typical class of frequent travellers provides a particularly good opportunity to study the relationship between transnational activities and cosmopolitanism. We also comprehensively investigate the link between postmaterialist values and cosmopolitan attitudes. We test our arguments using an original dataset that includes a relatively large sample of the German positional top elite in the years 2011 and 2012. A comparison between these data and data from a general population survey shows that while transnational activities affect the attitudes of ordinary citizens, increased travelling does not make elites more cosmopolitan. We discuss several reasons why this might be the case. We also observe that postmaterialist values and the ideological environment of the elite play a key role. Finally, we tentatively suggest that cosmopolitan elites do not endanger national social cohesion, as some fear they might. We show that cosmopolitanism and localism are not mutually exclusive and that members of the German elite feel even more attached to their nation than ordinary Germans.     

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.     

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.     

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....     

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.