Undulated cylinders of charged diblock copolymers

We study the cylinder to sphere morphological transition of diblock copolymers in aqueous solution with a hydrophobic block and a charged block. We find a metastable undulated cylinder configuration for a range of charge and salt concentrations which, nevertheless, occurs above the threshold where spheres are thermodynamically favorable. By modeling the shape of the cylinder ends, we find that the free energy barrier for the transition from cylinders to spheres is quite large and that this barrier falls significantly in the limit of high polymer charge and low solution salinity. This suggests that observed undulated cylinder phases are kinetically trapped structures

Food Prices and Blood Cholesterol

Cardiovascular diseases (CVD) cost Americans hundreds in billions of dollars. High cholesterol levels, which are closely related to diet habits, are a major contributor to CVD. In this paper we study whether changes in food prices are related to cholesterol levels and whether taxes or subsidies of particular foods would be effective in lowering cholesterol levels and, consequently, CVD costs. We find that prices of vegetables, processed foods, and whole milk and whole grains significantly affect the blood cholesterol levels. Having analyzed the costs and benefits of government interventions, we find that a subsidy of vegetables and whole grains would be the most efficient way to reduce CVD expenditures.cholesterol, CVD, cardio-vascular, food prices, health, welfare, Agricultural and Food Policy, Consumer/Household Economics, Food Consumption/Nutrition/Food Safety, Health Economics and Policy, D04, D12, D62, H23, I19, Q18,

Do Food Prices Affect Food Security? Evidence from the CPS 2002-2006

In this paper, we estimate the effect of food prices on food insecurity for SNAP recipients using data from the Current Population Survey and the recently published Quarterly Food At Home Price Database. We form a local food price index based on amounts of food for a household of four as established by the Thrifty Food Plan. We use an econometric model that accounts for the endogeneity of SNAP receipt to food insecurity and for household-level unobservables. We find that the average effect of food prices on the probability of food insecurity is positive and significant: an increase of one standard deviation in the price of our food basket is associated with an increase in food insecurity of between 1.3 and 2 percentage points for SNAP households. These results are fairly large in terms of the prevalence of food insecurity in our sample. An increase in food insecurity of this magnitude would be about 8 percent of total food insecurity prevalence for the populations in question. These results suggest that indexing SNAP benefits to local food prices could improve its ability to ameliorate the effects of food insecurity.food price, food insecurity, SNAP, discrete factor model, Demand and Price Analysis, Food Security and Poverty, I38,

Characteristics of modern atmospheric dust deposition in snow on the Penny Ice Cap, Baffin Island, Arctic Canada

We evaluated the concentration, size and distribution of insoluble dust microparticles in snowpits on the Penny Ice Cap (PIC), Baffin Island, to define (1) the characteristics of modern atmospheric dust deposition at the site, (2) the relative contributions of proximal and distal dust sources, and (3) the effects of summer melting on depositional signals in snow. The mean concentration (143 mg kg−1), flux (4.8 mg cm2 yr−1) and diameter (2.3 mm) of dust deposited on the PIC are similar to those observed in remote Arctic sites such as central Greenland, implying that dust is primarily supplied through long-range transport from far-removed source regions (at least 102–103 km distant). There is evidence for two seasonal maxima of dust deposition, one in late winter-early spring and one in late summer-early fall, although seasonal signals can not always be resolved in the snowpack due to some post-depositional particle migration with summer melt. However, ice layers appear to limit the mobility of particles, thereby preserving valuable paleoclimatic information in the PIC ice core dust record at a multi-annual to decadal temporal resolution