Development, Validation, and Assessment of an Ischemic Stroke or Transient Ischemic Attack-Specific Prediction Tool for Obstructive Sleep Apnea

BACKGROUND: Screening instruments for obstructive sleep apnea (OSA), as used routinely to guide clinicians regarding patient referral for polysomnography (PSG), rely heavily on symptomatology. We sought to develop and validate a cerebrovascular disease-specific OSA prediction model less reliant on symptomatology, and to compare its performance with commonly used screening instruments within a population with ischemic stroke or transient ischemic attack (TIA). METHODS: Using data on demographic factors, anthropometric measurements, medical history, stroke severity, sleep questionnaires, and PSG from 2 independently derived, multisite, randomized trials that enrolled patients with stroke or TIA, we developed and validated a model to predict the presence of OSA (i.e., Apnea-Hypopnea Index ≥5 events per hour). Model performance was compared with that of the Berlin Questionnaire, Epworth Sleepiness Scale (ESS), the Snoring, Tiredness, Observed apnea, high blood Pressure, Body mass index, Age, Neck circumference, and Gender instrument, and the Sleep Apnea Clinical Score. RESULTS: The new SLEEP Inventory (Sex, Left heart failure, ESS, Enlarged neck, weight [in Pounds], Insulin resistance/diabetes, and National Institutes of Health Stroke Scale) performed modestly better than other instruments in identifying patients with OSA, showing reasonable discrimination in the development (c-statistic .732) and validation (c-statistic .731) study populations, and having the highest negative predictive value of all in struments. CONCLUSIONS: Clinicians should be aware of these limitations in OSA screening instruments when making decisions about referral for PSG. The high negative predictive value of the SLEEP INventory may be useful in determining and prioritizing patients with stroke or TIA least in need of overnight PSG

Performing physiocracy: Pierre Samuel Du Pont de Nemours and the limits of political engineering

The story of Pierre Samuel Du Pont de Nemours has often been described as one of success. The man was a well-known statesman, economist and entrepreneur in late eighteenth-century France and his main legacy, the famous and still thriving Du Pont company, suggests a brilliant trajectory. The aim of this paper, however, is to analyze Du Pont's failure in performing the political and economic doctrine of which he was an active promoter all through his life: physiocracy. In all of his very diverse activities, be they scientific, political, or entrepreneurial, Du Pont indeed deliberately attempted to enact this original liberal doctrine. He tried, along with fellow physiocrats, to introduce freedom of trade and enterprise in Old Regime French minds and economic practices. Later, when emigrating to the United States, he devised a plan for a physiocratic colony. But none of these ventures was actually a success during Du Pont's lifetime: the performation of some of physiocracy's main propositions only came later, in a diffuse and partial way. We contend that this relative failure of performativity can be explained by Du Pont's specific type of agency: one relying mainly on political engineering, based on personal ties and reputations, as well as on a strict distinction between ends and means

Male density affects large-male advantage in the golden silk spider, Nephila clavipes

Across a variety of animal taxa, the outcome of male--male contests depends on male body size; winners are usually the larger males or the males with bigger weapons. However, high male density can either increase or reverse large-male advantage because density changes the frequency and intensity of male--male interactions. In the golden orb-web spider Nephila clavipes, large males have a competitive advantage in male--male contests. However, this species shows more than 2-fold variation in male body size and highly variable local male density (the number of males on a female's web). To test how male density affects large-male advantage, I manipulated male density on female webs. I measured how density affects the rate of male--male challenges and the body size of successful males. Large males have a reproductive advantage when male density is high and fighting among males is intense, but small and large males are equally likely to copulate successfully when male density is low, possibly because male--male interactions are infrequent at low densities. High variance in male density among female webs and the positive relationship between density and the strength of sexual selection for male body size create a heterogeneous mosaic of selection intensities. Spatial variation in selection intensity could act to maintain variation in male body size in this species. Copyright 2010, Oxford University Press.

Operational sex ratio and density do not affect directional selection on male sexual ornaments and behaviour

Demographic parameters including operational sex ratio (OSR) and population density may influence the opportunity for, and strength of sexual selection. Traditionally, male-biased OSRs and high population densities have been thought to increase the opportunity for sexual selection on male sexual traits due to increased male competition for mates. Recent experimental evidence, however, suggests that male-biased OSRs might reduce the opportunity for sexual selection due to increased sexual coercion experienced by females. How OSR, density, and any resultant changes in the opportunity for sexual selection actually affect selection on male sexual traits is unclear. In this study, we independently manipulated OSR and density in the guppy (Poecilia reticulata) without altering the number of males present. We recorded male and female behavior and used DNA microsatellite data to assign paternity to offspring and estimate male reproductive success. We then used linear selection analyses to examine the effects of OSR and density on directional sexual selection on male behavioral and morphological traits. We found that females were pursued more by males in male-biased treatments, despite no change in individual male behavior. There were no differences in sexual behavior experienced by females or performed by males in relation to density. Neither OSR nor density significantly altered the opportunity for sexual selection. Also, Although there was significant multivariate linear selection operating on males, neither OSR nor density altered the pattern of sexual selection on male traits. Our results suggest that differences in either OSR or density (independent of the number of males present) are unlikely to alter directional evolutionary change in male sexual traits