The forcing partial order on a family of braids forced by pseudo-Anosov 3-braids

Li-York theorem tells us that a period 3 orbit for a continuous map of the interval into itself implies the existence of a periodic orbit of every period. This paper concerns an analogue of the theorem for homeomorphisms of the 2-dimensional disk. In this case a periodic orbit is specified by a braid type and on the set of all braid types Boyland's dynamical partial order can be defined. We describe the partial order on a family of braids and show that a period 3 orbit of pseudo-Anosov braid type implies the Smale-horseshoe map which is a factor possessing complicated chaotic dynamics.Comment: 16 pages, 12 figure

Does Policy Matter? On Governments’ Attempts to Control Unwanted Migration

Public policy making on asylum takes place in an environment of intense public scrutiny, strong institutional constraints and international collective action problems. By assessing the relative importance of key pull factors of international migration, this article explains why, even when controlling for their differences in size, some states receive a much larger number of asylum seekers than others. The analysis of 20 OECD countries for the period 1985-1999 further shows that some of the most high profile public policy measures—safe third country provisions, dispersal and voucher schemes—aimed, at least in part, at deterring unwanted migration and at addressing the highly unequal distribution of asylum burdens have often been ineffective. This is because the key determinants of an asylum seeker’s choice of host country are historical, economic and reputational factors that largely lie beyond the reach of asylum policy makers. Finally, the paper argues that the effectiveness of unilateral policy measures will be further undermined by multilateral attempts to harmonise restrictive policies and that current efforts such as those by the European Union will consolidate, rather than effectively address, existing disparities in the distribution of asylum burdens.public policy effectiveness, asylum, migration pull factors, deterrence, burden sharing, collective action problems, international co-operation, European Union

Roles of familiarity and novelty in visual preference judgments are segregated across object categories

Understanding preference decision making is a challenging problem because the underlying process is often implicit and dependent on context, including past experience. There is evidence for both familiarity and novelty as critical factors for preference in adults and infants. To resolve this puzzling contradiction, we examined the cumulative effects of visual exposure in different object categories, including faces, natural scenes, and geometric figures, in a two-alternative preference task. The results show a clear segregation of preference across object categories, with familiarity preference dominant in faces and novelty preference dominant in natural scenes. No strong bias was observed in geometric figures. The effects were replicated even when images were converted to line drawings, inverted, or presented only briefly, and also when spatial frequency and contour distribution were controlled. The effects of exposure were reset by a blank of 1 wk or 3 wk. Thus, the category-specific segregation of familiarity and novelty preferences is based on quick visual categorization and cannot be caused by the difference in low-level visual features between object categories. Instead, it could be due either to different biological significances/attractiveness criteria across these categories, or to some other factors, such as differences in within-category variance and adaptive tuning of the perceptual system

Gender Inclusion in Climate Change Adaptation

There is increasing evidence that climate change has an impact on natural disasters, such as flooding, and on agricultural production, both of which have implications for gender issues. In this paper the authors briefly review issues related to gender and poverty and examine the relationships between gender and various indices. They then look at systems of land ownership and inheritance, and discuss an example of job recovery after a disaster through interviews with three female agricultural workers in Japan. The results of the interviews demonstrate the recent empowerment of women in agricultural production and that these women have strong adaptive abilities.climate change; natural disasters; gender issues; agricultural production