Auditory evoked potentials as a function of sleep deprivation

Event-related brain potentials (ERPs) were studied in subjects deprived of sleep over a 48-h test period to assess the effects of different durations of continuous wakefulness on ERP components and to determine whether changes in the ERP components were related to changes in performance. Forty subjects were randomly assigned to either an experimental (sleep deprived) group (n = 30) or a control (not sleep deprived) group (n = 10). For the experimental subjects, ERP and performance measures were obtained in four-h test blocks throughout the 48-h period. Performance was assessed using the Walter Reed performance assessment battery. The control subjects were tested at the same times except during designated sleep periods. Both performance and evoked potential measures showed systematic changes over the experimental test period in association with sleep deprivation, time of day, and repeated testing. The latency of the N2 component of the evoked potential covaried with throughput measures on the performance assessment battery across the 12 four-h test blocks of the experiment. These data suggest that ERPs reflect central processes that change across the sleep deprivation period and that ERP measures might be useful in assessment and prediction of performance degradation under adverse conditions such as sleep loss.     

《凤子》中反讽的各个侧面（下）

在《凤子》中,沈从文破除了归隐的基础、文化预设、物质可能和终极目的,涉及的是归隐的不可能性。沈从文以反讽为特色的隐士的归隐应当被理解为哲学和神秘意义上的归隐。沈从文的所有思考经过了反讽的筛选都被改头换面了,反讽性的超脱,相对于严肃的彻底超脱只是局部的。另外,这是一种双重的超脱：一方面,作者虽不乏公民与政治意识,但这却不成为一种崇拜;另一方面,生命的张力和对知识的相对化阻止了向神秘主义的转变。沈从文的人物并不逃避,他们生活在现实中。从根本上,沈从文将一个以极端化为特色的时代加以相对化。     

Aging society,health and the environment

In a general-equilibrium OLG model with endogenous longevity, a political economy and a social planner solution are contrasted mainly with respect to public supplies of health care and environment protection. The latter is relatively more supported by the young because its beneficial effect on longevity takes more time to occur but then lasts longer; while the old relatively prefer health spending. With population aging, political claims for health care expenditure are self-reinforcing. This framework is able to generate a quite rich set of results. In the political economy larger health care/consumption and health care/environmental quality ratios are implemented. Changes in risk aversion, production pollution, health inputs’ elasticity of substitution may have opposite impacts across regimes. More complete annuity markets improve welfare. Further comparative statics is analyzed.     

Approximating distributions of random functionals of Ferguson-Dirichlet priors

We explore the possibility of approximating the Ferguson-Dirichlet prior and the distributions of its random functionals through the simulation of random probability measures. The proposed procedure is based on the constructive definition illustrated in Sethuraman (1994) in conjunction with the use of a random stopping rule. This allows us to set in advance the closeness to the distributions of interest. The distribution of the stopping rule is derived, and the practicability of the simulating procedure is discussed. Sufficient conditions for convergence of random functionals are provided. The numerical applications provided just sketch the idea of the variety of nonparametric procedures that can be easily and safely implemented in a Bayesian setting.     

Maximum likelihood estimation of heterogeneous mixtures of Gaussian and uniform distributions

Existence and consistency of the Maximum Likelihood estimator of the parameters of heterogeneous mixtures of Gaussian and uniform distributions with known number of components are shown under constraints to prevent the likelihood from degeneration and to ensure identifiability. The EM-algorithm is discussed, and for the special case with a single uniform component a practical scheme to find a good local optimum is proposed. The method is compared theoretically and empirically to the estimation of a Gaussian mixture with “noise component” as introduced by Banfield and Raftery (1993) to find out whether it is a worthwhile alternative particularly in situations with outliers and points not belonging to the Gaussian components.     

Extending the family of Bayesian bootstraps and exchangeable urn schemes

A Bayesian bootstrap for a finite population with censored observations is introduced. It is shown to reduce to the finite population Bayesian bootstrap if there is no censoring and to reduce to the censored data Bayesian bootstrap for a large population. A class of general urn schemes for simulating exchangeable sequences of variables is introduced which is connected to the bootstrap method.     

Conjugate Priors Represent Strong Pre-Experimental Assumptions

Abstract.  It is well known that Jeffreys' prior is asymptotically least favorable under the entropy risk, i.e. it asymptotically maximizes the mutual information between the sample and the parameter. However, in this paper we show that the prior that minimizes (subject to certain constraints) the mutual information between the sample and the parameter is natural conjugate when the model belongs to a natural exponential family. A conjugate prior can thus be regarded as maximally informative in the sense that it minimizes the weight of the observations on inferences about the parameter; in other words, the expected relative entropy between prior and posterior is minimized when a conjugate prior is used.     

A Systematic Literature Review on Recent Lean Research: State‐of‐the‐art and Future Directions

Lean management (LM) has attracted the interest of scientists and practitioners since 1990, when Womack et al. (Womack, J.P., Jones, D.T. and Roos, D. (1990). The Machine that Changed the World. New York, NY: Rawson Associates) popularized the Japanese manufacturing approach aimed at eliminating waste to improve operational performance and customer satisfaction. Over the years, the lean concept has evolved becoming a managerial paradigm applicable to different sectors and processes with impressive results. This heterogeneity of implementations and settings makes the recent LM literature diverse and fragmented, and an extensive analysis of the latest contributions on this field is lacking. To address this gap, the authors propose a systematic literature review (SLR) of 240 articles published in 25 peer‐reviewed academic journals from January 2003 to December 2015. The purpose is to analyse the recent trends in this area and to provide a framework that organizes lean researched issues into mature, intermediate and nascent, based on their position in the research life cycle. Starting from the gaps that the SLR highlights, the authors suggest conducting lean research in the following directions: (a) grounding lean studies on existing managerial theories; (b) addressing service settings such as banking/finance, public sector and education; (c) exploring the role of national culture through cross‐country comparisons; (d) defining and conceptualizing ‘lean‐x’ processes; (e) understanding the relationships between lean and safety/environmental issues, and (f) unveiling the effects on social outcomes. Finally, the proposed framework helps scholars find issues not sufficiently explored that require theory‐building research (to move from nascent to intermediate) or theory‐testing research (to move from intermediate to mature).     

EQUILIBRIUM SEARCH UNEMPLOYMENT,ENDOGENOUS PARTICIPATION,AND LABOR MARKET FLOWS

The sustainability of welfare states requires high employment and high participation to raise the tax base. To analyze labor supply in a world with market frictions, we propose and solve a macro model of the labor market with unemployment and labor force participation as endogenous and distinct states. In our world, workers' decisions of participating are determined by an entry decision and an exit decision. A calibration of the model improves the usual representations of labor markets, since it quantitatively accounts for the observed flows between employment and nonparticipation. The paper investigates also the effect of payroll taxes and unemployment benefits on participation decisions. Taxes reduce entries and increase exits, whereas unemployment benefits, at a given job‐finding rate, raise entries and have ambiguous effects on exits. (JEL: J2, J6)