Many variable selection methods for linear regression depend critically on tuning parameters that control the performance of the method, e.g., “entry” and“stay” significance levels in forward and backward selection. However, most methods do not adapt the tuning parameters to particular data sets. We propose a general strategy for adapting variable selection tuning parameters that effectively es...

Buxton, Orfeu M., Mireille L’Hermite-Balériaux, Fred W. Turek, and Eve Van Cauter. Daytime naps in darkness phase shift the human circadian rhythms of melatonin and thyrotropin secretion. Am. J. Physiol. Regulatory Integrative Comp. Physiol. 278: R373–R382, 2000.—To systematically determine the effects of daytime exposure to sleep in darkness on human circadian phase, four groups of subjects pa...

Relationships between transient upper-tropospheric troughs and warm season convective activity over the southwest United States and northern Mexico are explored. Analysis of geopotential height and vorticity fields from the North American Regional Reanalysis and cloud-to-ground lightning data indicates that the passage of mobile inverted troughs (IVs) significantly enhances convection when it c...

The effects of chronic (14 day) intracerebroventricular infusion of various amounts of ovine corticotropin-releasing factor (oCRF) on the circadian blood corticosterone rhythm in male rats were examined. Control (saline-infused) rats showed distinct blood corticosterone rhythms over 48 h with nadirs at 0900 h and peaks at 2100 h on days 6-7 and 13-14. oCRF at 3 pmol/h did not affect the circadi...

New sampling theorems are developed for isotropic randomfields and their associated Fourier coefficient processes. A wavenumber-limited isotropic random field z ( ? ) is considered whose spectral densityfunction is zero outside a disk of radius B centered at the origin of the Manuscript received September 3, 1986; revised February 19, 1988. Thiswork was supported in part by the ...

BACKGROUND: This work analyzes the effect of social isolation (a mild stressor) on the 24-h variation of pituitary-testicular function in young Wistar rats, assessed by measuring circulating levels of prolactin, FSH, LH and testosterone. METHODS: Animals were either individually caged or kept in groups (4-5 animals per cage) under a 12:12 h light-dark cycle (lights on at 0800 h) for 30 days sta...

The present study was conducted to evaluate the endocrinological effects of the pituitary on luteal maintenance and regression in the cyclic golden hamster (Mesocritus auratus). After hypophysectomy (Hypox) at 0900 h on day 1 of the estrous cycle (the day of ovulation), the animals received injection of prolactin (PRL) or PRL plus equine chorionic gonadotropin (eCG). They were decapitated at 15...

This study aimed at determining the effect of the increase of foraging opportunities on the behaviour and welfare of breeding mares housed in individual boxes but allowed outside 6 h a day in a bare paddock. One hundred Arab breeding mares were divided into two groups of 50 according to the treatment and allowed outside in two bare paddocks at the same density (115 mare/ha) where water and shel...

the purpose of this experiment was to determine the effect of long-term low-dose administration of mercury (hg) on thyroid function in sheep. in this experiment, 10 clinically healthy, adult, male iranian sheep, aged approximately 1 year, were randomly allocated into the control (n=5) and mercury (hg-)-treated (n=5) groups. both groups were kept under identical conditions in terms of food and e...

body weight is influenced by both food intake and energy expenditure. acylated ghrelin enhances appetite, and its circulating level is suppressed by growth hormone. data on the acylated ghrelin responses to exercise of different intensities in obese individuals are currently not available. this study examined the effects of an intermittent exercise protocol on acylated ghrelin levels and hunger...