Christopher M. Snyder

Memory Inflation During Chronic Viral Infection is Maintained by Continuous Production of Short-Lived Functional T Cells

During persistent murine cytomegalovirus (MCMV) infection, the T cell response is maintained at extremely high intensity for the life of the host. These cells closely resemble human CMV-specific cells, which compose a major component of the peripheral T cell compartment in most people. Despite a phenotype that suggests extensive antigen-driven differentiation, MCMV-specific T cells remain functional and respond vigorously to viral challenge. We hypothesized that a low rate of antigen-driven proliferation would account for the maintenance of this population. Instead, we found that most of these cells divided only sporadically in chronically infected hosts and had a short half-life in circulation. The overall population was supported, at least in part, by memory T cells primed early in infection, as well as by recruitment of naive T cells at late times. Thus, these data show that memory inflation is maintained by a continuous replacement of short-lived, functional cells during chronic MCMV infection.

A Dynamic Theory of Countervailing Power

In this article I develop a model of an infinitely repeated procurement auction with one buyer and several sellers. The buyer can accumulate a backlog of unfilled orders which, similar to a boom in demand, forces the sellers t o collude on a low price to prevent undercutting. If the buyers cost of shifting its consumption over time is low enough, then the extent of collusion is bounded away from the joint-profit-maximizing level even for discount factors approaching one. The model is extended to allow for multiple buyers. Large buyers are shown to obtain lower prices from the sellers. Buyer mergers increase profit for all buyers, not just the merging pair, at the expense of the sellers. In contrast, buyer growth through addition harms buyers that do not grow and benefits sellers.

Spending Differences Associated With the Medicare Physician Group Practice Demonstration

CONTEXT The Centers for Medicare & Medicaid Services (CMS) recently launched accountable care organization (ACO) programs designed to improve quality and slow cost growth. The ACOs resemble an earlier pilot, the Medicare Physician Group Practice Demonstration (PGPD), in which participating physician groups received bonus payments if they achieved lower cost growth than local controls and met quality targets. Although evidence indicates the PGPD improved quality, uncertainty remains about its effect on costs. OBJECTIVE To estimate cost savings associated with the PGPD overall and for beneficiaries dually eligible for Medicare and Medicaid. DESIGN Quasi-experimental analyses comparing preintervention (2001-2004) and postintervention (2005-2009) trends in spending of PGPD participants to local control groups. We compared estimates using several alternative approaches to adjust for case mix. SETTING Ten physician groups from across the United States. PATIENTS AND PARTICIPANTS The intervention group was composed of fee-for-service Medicare beneficiaries (n = 990,177) receiving care primarily from the physicians in the participating medical groups. Controls were Medicare beneficiaries (n = 7,514,453) from the same regions who received care largely from non-PGPD physicians. Overall, 15% of beneficiaries were dually eligible for Medicare and Medicaid. MAIN OUTCOME MEASURE Annual spending per Medicare fee-for-service beneficiary. RESULTS Annual savings per beneficiary were modest overall (adjusted mean

Is No. News Bad News? Information Transmission and the Role of "Early Warning" in the Principal-Agent Model

114, 95% CI,

Open Access and Academic Journal Quality

12-

Sustained CD8+ T Cell Memory Inflation after Infection with a Single-Cycle Cytomegalovirus

216). Annual savings were significant in dually eligible beneficiaries (adjusted mean

CD4+ T Cell Help Has an Epitope-Dependent Impact on CD8+ T Cell Memory Inflation during Murine Cytomegalovirus Infection

532, 95% CI,

Cross-Presentation of a Spread-Defective MCMV Is Sufficient to Prime the Majority of Virus-Specific CD8+ T Cells

277-

Do Buyer-Size Discounts Depend on the Curvature of the Surplus Function? Experimental Tests of Bargaining Models

786), but were not significant among nondually eligible beneficiaries (adjusted mean

Open Access as a Crude Solution to a Hold-up Problem in the Two-Sided Market for Academic Journals

59, 95% CI,