Pfaffian representations of cubic surfaces

Let K be a field of characteristic zero. We describe an algorithm which requires a homogeneous polynomial F of degree three in K[x_0,x_1,x_2,x_3] and a zero A of F in P^3_K and ensures a linear pfaffian representation of V(F) with entries in K[x_0,x_1,x_2,x_3], under mild assumptions on F and A. We use this result to give an explicit construction of (and to prove the existence of) a linear pfaffian representation of V(F), with entries in K'[x_0,x_1,x_2,x_3], being K' an algebraic extension of K of degree at most six. An explicit example of such a construction is given.Comment: 17 pages. Expanded with some remarks. Published with minor corrections in Geom. Dedicat

Analyzing Childlessness

Childlessness has been on the rise in many European societies. In Germany, the UK, Austria, the Netherlands, and Switzerland, childlessness has increased starting with the 1950s cohorts. In these countries, about 20 % of the women born around 1965 will remain childless. In southern Europe and the former state-socialist countries of Central and Eastern Europe, the rise in levels of childlessness is a more recent phenomenon. Yet among younger cohorts in these countries, childlessness has reached levels of 15 % or higher. In this introductory chapter, we summarize the long-term trends in childlessness and discuss the differences between European countries in the prevalence of childlessness. We also outline the structure and the logic of this volume

The demographic consequences of assisted reproductive technologies

The use of assisted reproductive technology (ART) is widespread, with an estimated five million ART-conceived children born now worldwide. Despite this marked increase in the use of ART, little is known about the demographic consequences. We explore several dimensions of demographic consequences of ART. The proportion of ART-conceived babies varies greatly across countries, and our analyses suggest that ART costs, policies and regulations, and national norms and values are core determi- nants of these differences. Based on a review of the literature, we conclude that ART has a negligible impact on national fertility rates, thereby sug- gesting that it is not an effective policy instrument to counter low fertility. Furthermore, we show that the recent increase in twin births in Europe can be attributed to ART usage. A case study of Italy reveals that ART mothers were more likely to deliver prematurely, even when controlling for maternal age

The demographic consequences of assisted reproductive technologies

The use of assisted reproductive technology (ART) is widespread, with an estimated five million ART-conceived children born now worldwide. Despite this marked increase in the use of ART, little is known about the demographic consequences. We explore several dimensions of demographic consequences of ART. The proportion of ART-conceived babies varies greatly across countries, and our analyses suggest that ART costs, policies and regulations, and national norms and values are core determi- nants of these differences. Based on a review of the literature, we conclude that ART has a negligible impact on national fertility rates, thereby sug- gesting that it is not an effective policy instrument to counter low fertility. Furthermore, we show that the recent increase in twin births in Europe can be attributed to ART usage. A case study of Italy reveals that ART mothers were more likely to deliver prematurely, even when controlling for maternal age

State-of-the-art report childlessness in Europe

In the last decades, European societies have experienced changes in the postponement of the age of having a first child, shrinking family size, and increased (in)voluntary childlessness. This report provides a review of the state-of-the-art research in relation to one of the central research goals of Working Package 4: to examine the rise, determinants and societal consequences of childlessness by different perspectives. The report provides an overview of the central macro-level determinants of childlessness among women and men firstly from a quantitative perspective examining trends, relevant determinants and measures. We will then outline the central micro-level determinants of childlessness among women, men and couples by examining core characteristics of childless individuals such as higher education or marital disruption. We then turn to an overview of anthropological and qualitative examinations of the determinants of childlessness and the psychological, social and socio-political consequences of childlessness. A reflection on potential data sources to study childlessness and a discussion on research gaps are offered in the concluding chapters. </p

Between change and continuity: fathers and work-family balance in Italy

The chapter discusses the changing role of men and fathers and particularly fathers’ work-family concerns in the Italian context. A review of international literature on fathers’ identity and roles, on policies supporting fathers in work-family balance and an analysis of Italian national data (ISTA Multipurpose Survey on Households) will allow us to explore the transformation that affects fathering. Our data confirm that although the time spent by fathers with children is increasing, there is still a considerable gap between the maternal and the paternal involvement. Parenting is still deeply gendered in terms of daily childcare activities, the relationship between care and paid work, discourses on what is appropriate and who has ultimate responsibility for nurturing and caring The help offered by grandparents is crucial but does not challenge the gendered division of care. Data also suggest a strong relation between paternal and maternal job patterns, thus our hypothesis that gender roles are relational and influenced by the family/couple structure seems confirmed