711 research outputs found
On the Road: Images of Truthtelling in Rural America
This narrative is a true story. It raises the same central issue as many of the core stories of race and gender that have haunted us over the last decade: the identification of truthtellers. Theoretical analysis of truth and bias abound. This story, like many of these other stories, nevertheless stands on its own, without the need for iterative analysis
Timing of a Single Daily Meal and Diel Variations of Serum Thyroxine, Triiodothyronine and Cortisol in Goldfish Carassius auratus
Two groups of goldfish were maintained on a 12L:12D photoperiod at 19°C and fed either at 0800 (light onset) or 1600 h daily. After 3 weeks, blood samples were taken at one of six times of day and the serum was analyzed for thyroxine, triiodothyronine, and cortisol by radioimmunoassay. Fish fed in the morning had significant diel variations in circulating titers of thyroxine and cortisol, those fed in the afternoon had significant variations of thyroxine and triiodothyronine. Meal feeding appeared to entrain, and phase shift, the cortisol rhythm but not the rhythms of thyroid hormones. These results are briefly discussed in light of the effects of timing the daily meal on weight gain in fish
Fluctuations of the partial filling factors in competitive RSA from binary mixtures
Competitive random sequential adsorption on a line from a binary mix of
incident particles is studied using both an analytic recursive approach and
Monte Carlo simulations. We find a strong correlation between the small and the
large particle distributions so that while both partial contributions to the
fill factor fluctuate widely, the variance of the total fill factor remains
relatively small. The variances of partial contributions themselves are quite
different between the smaller and the larger particles, with the larger
particle distribution being more correlated. The disparity in fluctuations of
partial fill factors increases with the particle size ratio. The additional
variance in the partial contribution of smaller particle originates from the
fluctuations in the size of gaps between larger particles. We discuss the
implications of our results to semiconductor high-energy gamma detectors where
the detector energy resolution is controlled by correlations in the cascade
energy branching process.Comment: 19 pages, 8 figure
Report of the sensor readout electronics panel
The findings of the Sensor Readout Electronics Panel are summarized in regard to technology assessment and recommended development plans. In addition to two specific readout issues, cryogenic readouts and sub-electron noise, the panel considered three advanced technology areas that impact the ability to achieve large format sensor arrays. These are mega-pixel focal plane packaging issues, focal plane to data processing module interfaces, and event driven readout architectures. Development in each of these five areas was judged to have significant impact in enabling the sensor performance desired for the Astrotech 21 mission set. Other readout issues, such as focal plane signal processing or other high volume data acquisition applications important for Eos-type mapping, were determined not to be relevant for astrophysics science goals
Random sequential adsorption of shrinking or spreading particles
We present a model of one-dimensional irreversible adsorption in which
particles once adsorbed immediately shrink to a smaller size or expand to a
larger size. Exact solutions for the fill factor and the particle number
variance as a function of the size change are obtained. Results are compared
with approximate analytical solutions.Comment: 9 pages, 8 figure
Circadian Variation of Brain Histamine in Goldfish
Teleosts may make an excellent model to study brain histamine function. Fishes are phylogenetically closer to the basic vertebrate blueprint than higher vertebrates. They appear to have a simpler histaminergic system in terms of central nervous system distribution and, contrary to higher vertebrates, brain histamine appears to be strictly neuronal. In this preliminary study, we examined circadian variation of brain histamine in goldfish, Carassius auratus, as this neurotransmitter correlates with circadian behavior of some mammals. Two groups of juvenile goldfish were held in 24 60L aquaria, six fish per aquarium, on reversed photoperiods; L:D 12:12 with light onset either at 0700 or 1900 h. Fish were sampled every 4 h. At a sampling time, all the fish in a tank were taken; each sampling, for both groups, was done in replicate. Brain histamine was determined by immunoassay. There was a significant circadian variation in histamine on both photoperiod regimes with the highest levels during the photophase. These results support the hypothesis of an early phylogenic role for histamine in vertebrate circadian physiology
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