Distribution of lipids in non-lamellar phases of their mixtures

We consider a model of lipids in which a head group, characterized by its volume, is attached to two flexible tails of equal length. The phase diagram of the anhydrous lipid is obtained within self-consistent field theory, and displays, as a function of lipid architecture, a progression of phases: body-centered cubic, hexagonal, gyroid, and lamellar. We then examine mixtures of an inverted hexagonal forming lipid and a lamellar forming lipid. As the volume fractions of the two lipids vary, we find that inverted hexagonal, gyroid, or lamellar phases are formed. We demonstrate that the non-lamellar forming lipid is found preferentially at locations which are difficult for the lipid tails to reach. Variations in the volume fraction of each type of lipid tail are on the order of one to ten per cent within regions dominated by the tails. We also show that the variation in volume fraction is correlated qualitatively with the variation in mean curvature of the head-tail interface.Comment: 10 pages, 12 figures (better figures are available upon request), to appear in J. Chem. Phy

Networks, commuting and spatial structures: An introduction

JTLU vol. 2, no. 3, (2010) pp 1-4This article introduces vol. 2, no. 3 issue of Journal of Transport and Land Use

Bridging youth and gender studies to analyse rural young women and men's livelihood pathways in Central Uganda

Abstract Many development countries are currently undergoing major demographic shifts as the percentage of young people of the total population rapidly increases. This shift is associated with high rates of migration, unemployment and instability. In policy discourses, engaging youth in commercial agricultural is often presented as a measure to control or even counter these trends. In Uganda, a country with one of the youngest populations in the world, we investigated whether young people themselves see a career in farming as an option. We studied the livelihood pathways of rural-born young men and women from Central Uganda and in particular; 1) their aspirations, 2) the extent to which these aspirations are associated with agriculture, and 3) the importance of gender in shaping their opportunity spaces. Data consisted of in-depth interviews with 8 young men and 8 young women originating from the same rural community in Central Uganda (2017) and was supported by three additional datasets collected between 2010 and 2014; one qualitative case-study conducted in the same site (2014) and two survey datasets collected in three rural sites in Central Uganda in 2010 (N = 199) and 2012 (N = 54). Our findings suggest a large proportion of youth out-migrating from the rural communities, with young women migrating more often than young men. Farming was seldom an aspiration but irrespective of sex or residence most young men and women did remain engaged in agriculture in some way. The nature of the engagement was different for men and women though, with young women specifically refraining from commercial agriculture. By analyzing the opportunity space of young men and women, we uncovered how their livelihood pathways were linked to a set of normative and structural constraints maintaining gender inequality. Examples were young women's weaker resource base (land) and gender norms which discourage young women's independent commercial (agricultural) activities. To advance the engagement of young men and especially women in commercial agriculture, it is important to acknowledge these patterns and their underlying structural gender differences

Spatial economic impacts of developing international top office locations: a case study for Amsterdam South

A strong competition takes place between large European cities for attracting international head offices in especially the services sector. This paperinvestigates the spatial economic and employment impacts of developing such a top location. First, a theoretical overview is presented on generativeeconomic growth and the locational behaviour of companies. Then attention is paid to the potential employment and spatial economic impacts (bothdistributive and generative) of such a project. In the second part of the paper, a case study is presented for Amsterdam South, which the localgovernment wishes to develop as an international top office location. It appears that there are indications of generativeemployment impacts, but that there may also occur distributive effects, e.g. relocation of firms from the city centre towards the new location. It isconcluded that both psychological factors and a careful planning are very important for the development of top locations. When a project is successful,new employment may be generated, but undesirable distributive impacts may be substantial

Economic evaluation of safety measures for transport companies

Measures to reduce material damage within companies may both increase the business economic performance of the company and traffic safety in general. In this paper the notion of whether such measures are economically feasible is investigated. Results are presented of a series of interviews amongtransport companies and of a postal questionnaire survey. Next, calculations are presented for three types of companies: a small family company, a large family company and a large formalised company. The main conclusions are that a successful introduction of measures is largely influenced bypsychological and cultural factors. Especially in larger companies, substantial cost savings may occur due to an active material damage preventionpolicy, which will also have positive impacts on traffic safety in general

Genetic predispositions moderate the effectiveness of tobacco excise taxes.

BACKGROUND: Tobacco consumption is one of the leading causes of preventable death. In this study, we analyze whether someone's genetic predisposition to smoking moderates the response to tobacco excise taxes. METHODS: We interact polygenic scores for smoking behavior with state-level tobacco excise taxes in longitudinal data (1992-2016) from the US Health and Retirement Study (N = 12,058). RESULTS: Someone's genetic propensity to smoking moderates the effect of tobacco excise taxes on smoking behavior along the extensive margin (smoking vs. not smoking) and the intensive margin (the amount of tobacco consumed). In our analysis sample, we do not find a significant gene-environment interaction effect on smoking cessation. CONCLUSIONS: When tobacco excise taxes are relatively high, those with a high genetic predisposition to smoking are less likely (i) to smoke, and (ii) to smoke heavily. While tobacco excise taxes have been effective in reducing smoking, the gene-environment interaction effects we observe in our sample suggest that policy makers could benefit from taking into account the moderating role of genes in the design of future tobacco control policies