Cohort Crowding: How Resources Affect Collegiate Attainment

Analyses of college attainment typically focus on factors affecting enrollment demand, including the financial attractiveness of a college education and the availability of financial aid, while implicitly assuming that resources available per student on the supply side of the market are elastically supplied. The higher education market in the United States is dominated by public and non-profit production, and colleges and universities receive considerable subsidies from state, federal, and private sources. Because consumers pay only a fraction of the cost of production, changes in demand are unlikely to be accommodated fully by colleges and universities without commensurate increases in non-tuition revenue. For this reason, public investment in higher education plays a crucial role in determining the degrees produced and the supply of college-educated workers to the labor market. Using data covering the last half of the twentieth century, we find strong evidence that large cohorts within states have relatively low undergraduate degree attainment, reflecting less than perfect elasticity of supply in the higher education market. That large cohorts receive lower public subsidies per student in higher education explains this result, indicating that resources have large effects on degree production. Our results suggest that reduced resources per student following from rising cohort size and lower state expenditures are likely to have significant negative effects on the supply of college-educated workers entering the labor market.

From a thin film model for passive suspensions towards the description of osmotic biofilm spreading

Biofilms are ubiquitous macro-colonies of bacteria that develop at various interfaces (solid-liquid, solid-gas or liquid-gas). The formation of biofilms starts with the attachment of individual bacteria to an interface, where they proliferate and produce a slimy polymeric matrix - two processes that result in colony growth and spreading. Recent experiments on the growth of biofilms on agar substrates under air have shown that for certain bacterial strains, the production of the extracellular matrix and the resulting osmotic influx of nutrient-rich water from the agar into the biofilm are more crucial for the spreading behaviour of a biofilm than the motility of individual bacteria. We present a model which describes the biofilm evolution and the advancing biofilm edge for this spreading mechanism. The model is based on a gradient dynamics formulation for thin films of biologically passive liquid mixtures and suspensions, supplemented by bioactive processes which play a decisive role in the osmotic spreading of biofilms. It explicitly includes the wetting properties of the biofilm on the agar substrate via a disjoining pressure and can therefore give insight into the interplay between passive surface forces and bioactive growth processes

The EPSRC's policy of responsible innovation from a trading zones perspective

Responsible innovation (RI) is gathering momentum as an academic and policy debate linking science and society. Advocates of RI in research policy argue that scientific research should be opened up at an early stage so that many actors and issues can steer innovation trajectories. If this is done, they suggest, new technologies will be more responsible in different ways, better aligned with what society wants, and mistakes of the past will be avoided. This paper analyses the dynamics of RI in policy and practice and makes recommendations for future development. More specifically, we draw on the theory of ‘trading zones’ developed by Peter Galison and use it to analyse two related processes: (i) the development and inclusion of RI in research policy at the UK’s Engineering and Physical Sciences Research Council (EPSRC); (ii) the implementation of RI in relation to the Stratospheric Particle Injection for Climate Engineering (SPICE) project. Our analysis reveals an RI trading zone comprised of three quasi-autonomous traditions of the research domain – applied science, social science and research policy. It also shows how language and expertise are linking and coordinating these traditions in ways shaped by local conditions and the wider context of research. Building on such insights, we argue that a sensible goal for RI policy and practice at this stage is better local coordination of those involved and we suggest ways how this might be achieved

Consumption soothing and vulnerability in the Zone Lacustre, Mali

"This paper explores risk sharing in the Zone Lacustre, Mali, as viewed through the lens of consumption smoothing. We find that idiosyncratic shocks appear to have little impact on consumption, and that households respond to these shocks in a variety of ways. In general, nonpoor households are more likely to enter into new income-generating activities while poor households are more likely to engage in credit or gift exchange or to ration consumption. When we construct a stronger test for consumption smoothing, we find that changes in household income lead to modest changes in consumption. Covariant shocks, as measured by village/round dummies, always lead to changes in consumption. These results are robust to concerns regarding bias resulting from measurement error or endogeneity of changes in income. Lastly, we find that households with access to improved water control infrastructure are less vulnerable than those that rely on rainfall or the flooding of the Niger River." Authors' AbstractVulnerability ,Consumption shocks ,

Modelling of surfactant-driven front instabilities in spreading bacterial colonies

The spreading of bacterial colonies at solid-air interfaces is determined by the physico-chemical properties of the involved interfaces. The production of surfactant molecules by bacteria is a widespread strategy that allows the colony to efficiently expand over the substrate. On the one hand, surfactant molecules lower the surface tension of the colony, effectively increasing the wettability of the substrate, which facilitates spreading. On the other hand, gradients in the surface concentration of surfactant molecules result in Marangoni flows that drive spreading. These flows may cause an instability of the circular colony shape and the subsequent formation of fingers. In this work, we study the effect of bacterial surfactant production and substrate wettability on colony growth and shape within the framework of a hydrodynamic thin film model. We show that variations in the wettability and surfactant production are sufficient to reproduce four different types of colony growth, which have been described in the literature, namely, arrested and continuous spreading of circular colonies, slightly modulated front lines and the formation of pronounced fingers

Consumption soothing and vulnerability in the Zone Lacustre, Mali

"This paper explores risk sharing in the Zone Lacustre, Mali, as viewed through the lens of consumption smoothing. We find that idiosyncratic shocks appear to have little impact on consumption, and that households respond to these shocks in a variety of ways. In general, nonpoor households are more likely to enter into new income-generating activities while poor households are more likely to engage in credit or gift exchange or to ration consumption. When we construct a stronger test for consumption smoothing, we find that changes in household income lead to modest changes in consumption. Covariant shocks, as measured by village/round dummies, always lead to changes in consumption. These results are robust to concerns regarding bias resulting from measurement error or endogeneity of changes in income. Lastly, we find that households with access to improved water control infrastructure are less vulnerable than those that rely on rainfall or the flooding of the Niger River." Authors' AbstractVulnerability ,Consumption shocks ,