Poliovirus-specific primer-dependent RNA polymerase able to copy poly(A)

A template-dependent RNA polymerase has been isolated from poliovirus-infected cells by assaying for the ability of the enzyme to copy poly(A) complexed to an oligo(U) primer. The polymerase was solubilized with detergent, and RNA was removed by precipitation with 2 M LiCl. The solubilized polymerase required both poly(A) and oligo(U) for activity and was stimulated by Mg2+ but was inhibited by Mn2+. Poly(A)· oligo(U)-dependent poly(U) polymerase was not found in extracts of HeLa cells until about 2 hr after poliovirus infection, and then there was a linear increase in activity until about 5 hr. Analysis of the polymerase by glycerol gradient centrifugation showed that the majority of the activity sedimented at about 4 S, indicating that it was no longer complexed with high-molecular-weight RNA or cellular membranes. This poly(A)· oligo(U)-dependent polymerase activity could represent an important component of the poliovirus RNA-dependent RNA polymerase

Pseudoeurycea unguidentis

Number of Pages: 2Integrative BiologyGeological Science

Two-player Knock 'em Down

We analyze the two-player game of Knock 'em Down, asymptotically as the number of tokens to be knocked down becomes large. Optimal play requires mixed strategies with deviations of order sqrt(n) from the naive law-of-large numbers allocation. Upon rescaling by sqrt(n) and sending n to infinity, we show that optimal play's random deviations always have bounded support and have marginal distributions that are absolutely continuous with respect to Lebesgue measure.Comment: 15 pages, 1 figure. v2 has minor revision

Pseudoeurycea longicauda

Number of Pages: 2Integrative BiologyGeological Science

"Managed Care, Physician Incentives, and Norms of Medical Practice: Racing to the Bottom or Pulling to the Top?"

The incentive contracts that managed care organizations write with physicians have generated considerable controversy. Critics fear that if informational asymmetries inhibit patients from directly assessing the quality of care provided by their physician, competition will lead to a "race to the bottom" in which managed care plans induce physicians to offer only minimal levels of care. To analyze this issue we propose a model of competition between managed care organizations. The model serves for both physician incentive contracts and HMO product market strategies in an environment of extreme information asymmetry--physicians perceive quality of care perfectly, and patients don't perceive it at all. We find that even in this stark setting, managed care organizations need not race to the bottom. Rather, the combination of product differentiation and physician practice norms causes managed care organizations to race to differing market niches, with some providing high levels of care as a means of assembling large physician networks. We also find that relative physician practice norms, defined endogenously by the standards of medical care prevailing in a market, exert a "pull to the top" that raises the quality of care provided by all managed care organizations in the market. We conclude by considering the implications of our model for public policies designed to limit the influence of HMO incentive systems.

Cruise noise of the 2/9th scale model of the Large-scale Advanced Propfan (LAP) propeller, SR-7A

Noise data on the Large-scale Advanced Propfan (LAP) propeller model SR-7A were taken in the NASA Lewis Research Center 8 x 6 foot Wind Tunnel. The maximum blade passing tone noise first rises with increasing helical tip Mach number to a peak level, then remains the same or decreases from its peak level when going to higher helical tip Mach numbers. This trend was observed for operation at both constant advance ratio and approximately equal thrust. This noise reduction or, leveling out at high helical tip Mach numbers, points to the use of higher propeller tip speeds as a possible method to limit airplane cabin noise while maintaining high flight speed and efficiency. Projections of the tunnel model data are made to the full scale LAP propeller mounted on the test bed aircraft and compared with predictions. The prediction method is found to be somewhat conservative in that it slightly overpredicts the projected model data at the peak

Properties of periodic arrays of symmetric complementary structuresand their application to grid amplifiers

Deschamps' theorem for n-terminal complementary structures is reviewed. An extension to Deschamps' theorem for a class of three-terminal bounded structures with one axis of symmetry is presented. It is shown that, for these structures, a simple relationship between the impedances of the odd mode of the original structure and the admittances of the even mode of the complementary structure exists, and that these modes are orthogonal. Using this, a self-complementary grid amplifier is designed and the measured results are presented

Self-Complementary Structures and Their Application in Grid Amplifiers

An extension to Deschamps’s theorem for a class of 3-terminal bounded structures with one axis of symmetry is presented. For these structures, a simple relationship between the impedance matrix of the odd mode excitation of the original structure and the admittance matrix of the even mode excitation of its complement exists. Using this, a self-complementary grid amplifier is designed and the measured results are presented