The Pediatric Emergency Care Applied Research Network: a history of multicenter collaboration in the United States.

In this article, we review the history and progress of a large multicenter research network pertaining to emergency medical services for children. We describe the history, organization, infrastructure, and research agenda of the Pediatric Emergency Care Applied Research Network (PECARN), and highlight some of the important accomplishments since its inception. We also describe the network's strategy to grow its research portfolio, train new investigators, and study how to translate new evidence into practice. This strategy ensures not only the sustainability of the network in the future, but the growth of research in emergency medical services for children in general

Macroscopic Kinetic Effect of Cell-to-Cell Variation in Biochemical Reactions

Genetically identical cells under the same environmental conditions can show strong variations in protein copy numbers due to inherently stochastic events in individual cells. We here develop a theoretical framework to address how variations in enzyme abundance affect the collective kinetics of metabolic reactions observed within a population of cells. Kinetic parameters measured at the cell population level are shown to be systematically deviated from those of single cells, even within populations of homogeneous parameters. Because of these considerations, Michaelis-Menten kinetics can even be inappropriate to apply at the population level. Our findings elucidate a novel origin of discrepancy between in vivo and in vitro kinetics, and offer potential utility for analysis of single-cell metabolomic data

Demand for Self Control: A model of Consumer Response to Programs and Products that Moderate Consumption

Is it better to apply effort to increase personal consumption, or control what one wants? The model presented here provides a characterization of demand for self control, namely, its responsiveness to price and risk. Unlike most other models of self control, the model does not identify self control with time inconsistency or rely on the multiple-selves framework. Self control refers to resources allocated to preference transformation technology enabling consumers to moderate desire for ordinary consumption by reducing threshold levels required to achieve goals or target-levels of consumption. Consumers face a choice between allocating resources toward increasing expected levels of consumption or increasing chances of contentment through self control. Because of strong income effects, demand for self control turns out to be non-monotonic in price and sometimes discontinuous, revealing potential for unanticipated and sometimes surprisingly large responses to small changes in price. The model is used to analyze consumers’ willingness to follow new regulations, take up credit counseling, enroll in financial literacy programs, and purchase products aimed at improving financial decision making through cultivation of self control.Preference Choice, Preference Change, Moderation, Restraint, Desire, Financial, Decision Making, Consumer Credit, Consumer Finance, Institutional Design, Ecological Rationality, Bounded Rationality, Behavioral Economics

The impact of monetary policy on New Zealand business cycles and inflation variability

This paper uses the open economy structural VAR model developed in Buckle, Kim, Kirkham, McLellan and Sharma (2002) to evaluate the impact of monetary policy on New Zealand business cycles and inflation variability and the output/ inflation variance trade-off. The model includes a forward- looking Taylor Rule to identify monetary policy and the impact of monetary policy is evaluated by deriving a monetary policy index using a procedure suggested by Dungey and Pagan (2000). Monetary policy has generally been counter-cyclical, thereby reducing business cycles and inflation variability. Exceptions are in 1993 when monetary policy accentuated the business cycle upswing and in 1998 when monetary policy accentuated the recession, although its impact in 1998 was small relative to the impact of adverse climatic conditions. During the initial years of inflation targeting monetary policy tended to simultaneously reduce inflation and output variability. From 1996 to 2001 monetary policy was less effective in reducing inflation and output variability. This latter period included a brief experiment with a Monetary Conditions Index, the Asian crisis and a large adverse domestic climate shock.Monetary policy; inflation targeting, business cycles; open economy; structural VAR models; inflation, interest rates, exchange rates, climate; international linkages

Can one hear the shape of a population history?

Reconstructing past population size from present day genetic data is a major goal of population genetics. Recent empirical studies infer population size history using coalescent-based models applied to a small number of individuals. Here we provide tight bounds on the amount of exact coalescence time data needed to recover the population size history of a single, panmictic population at a certain level of accuracy. In practice, coalescence times are estimated from sequence data and so our lower bounds should be taken as rather conservative.Comment: 22 pages, 7 figures; v2 is significantly revised from v

Nonlinear dynamics of mode-locking optical fiber ring lasers

We consider a model of a mode-locked fiber ring laser for which the evolution of a propagating pulse in a birefringent optical fiber is periodically perturbed by rotation of the polarization state owing to the presence of a passive polarizer. The stable modes of operation of this laser that correspond to pulse trains with uniform amplitudes are fully classified. Four parameters, i.e., polarization, phase, amplitude, and chirp, are essential for an understanding of the resultant pulse-train uniformity. A reduced set of four coupled nonlinear differential equations that describe the leading-order pulse dynamics is found by use of the variational nature of the governing equations. Pulse-train uniformity is achieved in three parameter regimes in which the amplitude and the chirp decouple from the polarization and the phase. Alignment of the polarizer either near the slow or the fast axis of the fiber is sufficient to establish this stable mode locking