Rotational diffusion of Escherichia coli ribosomes. I. - Free 70 S, 50 S and 30 S particles.

The rotational brownian diffusion of Escherichia coli ribosomes has been studied by following the transient dichroism generated by optical excitation of a covalent probe into its triplet state. The induced absorption anisotropy decays exponentially with characteristic correlation times: 2.5 microseconds, 1.6 microseconds and 1.1 microseconds for the 70S ribosome and the 50S and 30S subparticles respectively. The corresponding Stokes radii are in the same order, 133 A, 115 A and 103 A. The hydrodynamic properties are discussed in terms of an ellipsoidal shape of the ribosome particles.     

Trends in U.S. food prices, 1950-2007

The potential effect that food prices may have on the health of the U.S. population needs to be further explored, particularly in light of the rising food prices currently being observed. Declining food prices over time have been singled out as a main contributor, for example, to the rising trend in obesity. In this paper we use data from the Bureau of Labor Statistics, the American Chamber of Commerce Researchers Association, the Consumer Expenditure Survey, and the United States Department of Agriculture to analyze trends in various types of food prices, to create a food price index, and to estimate the price of a calorie. Results may be used by future researchers in estimating the health implications of these trends. We find that while the general trend in food prices has been declining, that of restaurant meal prices and prices of fruits and vegetables has risen over time. It is doubtful that the decline in food prices has been sufficiently large to account for the large increase in caloric intake that is said to have contributed to the obesity epidemic in the U.S.     

Six newSalmonella types,isolated in ghana (S. volta,S. agona,S. wa,S. techimani,S. mampong andS. tafo)

Summary Six newSalmonella types isolated in Ghana are described.S. volta, 11: 4: 1,z₁₃, z₂₈ was isolated from a swine;S.agona 4,12: fgs:—,S.wa, 16: b: 1,5S.technimani, 28: c: z₆ andS.tafo, 1, 4 12, 27: z₃₅: 1,7 were isolated from cattle;S.mampong, 13,22: z₃₅: 1,6, was isolated from a lizzard.