RESUMEN
The explosion that results in a cosmic gamma-ray burst (GRB) is thought to produce emission from two physical processes: the central engine gives rise to the high-energy emission of the burst through internal shocking, and the subsequent interaction of the flow with the external environment produces long-wavelength afterglows. Although observations of afterglows continue to refine our understanding of GRB progenitors and relativistic shocks, gamma-ray observations alone have not yielded a clear picture of the origin of the prompt emission nor details of the central engine. Only one concurrent visible-light transient has been found and it was associated with emission from an external shock. Here we report the discovery of infrared emission contemporaneous with a GRB, beginning 7.2 minutes after the onset of GRB 041219a (ref. 8). We acquired 21 images during the active phase of the burst, yielding early multi-colour observations. Our analysis of the initial infrared pulse suggests an origin consistent with internal shocks.
RESUMEN
The scholarly literature on health care politics has generated a series of hypotheses to explain U.S. exceptionalism in health policy and to explain the adoption of national health insurance (NHI) more generally. Various cultural, institutional, and political conditions are held to make the establishment of some form of national health insurance policy more (or less) likely to occur. The literature is dominated by national and comparative case studies that illustrate the theoretical logic of these hypotheses but do not provide a framework for examining the hypotheses cross-nationally. This article is an initial attempt to address that void by using Boolean analysis to examine systematically several of the major propositions that emerge from the case study literature on the larger universe of twenty advanced industrial democracies. This comparative analysis offers considerable support for the veto points hypothesis while still finding each of the factors examined to be relevant in certain scenarios. We conclude with a discussion of the implications of these findings for future research and for advocates of national health insurance in the United States.
