8,181 research outputs found
Effects of noise upon human information processing
Studies of noise effects upon human information processing are described which investigated whether or not effects of noise upon performance are dependent upon specific characteristics of noise stimulation and their interaction with task conditions. The difficulty of predicting noise effects was emphasized. Arousal theory was considered to have explanatory value in interpreting the findings of all the studies. Performance under noise was found to involve a psychophysiological cost, measured by vasoconstriction response, with the degree of response cost being related to scores on a noise annoyance sensitivity scale. Noise sensitive subjects showed a greater autonomic response under noise stimulation
Distribution of proteoglycans antigenically related to corneal keratan sulfate proteoglycan
Three antibodies reacting with corneal keratan sulfate proteoglycan were used to detect antigenically related molecules in 11 bovine and 13 embryonic chick tissues. Two monoclonal antibodies recognized sulfated epitopes on the keratan sulfate chain and a polyclonal antibody bound antigenic sites on the core protein of corneal keratan sulfate proteoglycan. Competitive immunoassay detected core protein and keratan sulfate antigens in guanidine HCl extracts of most tissues. Keratan sulfate antigens of most bovine tissues were only partially extracted with guanidine HCl, but the remainder could be solubilized by CNBr treatment of the guanidine-extracted residue. Keratan sulfate and core protein antigens co-eluted with purified corneal keratan sulfate proteoglycan on ion exchange high-performance liquid chromatography (HPLC). Endo-beta-galactosidase digestion of the HPLC-purified keratan sulfate antigens eliminated the binding of monoclonal anti-keratan sulfate antibodies in enzyme-linked immunosorbent assay. Extracts of all 11 bovine tissues, except those from brain and cartilage, could bind both anti-keratan sulfate monoclonal antibodies and anti-core protein polyclonal antibody simultaneously. Binding was sensitive to competition with keratan sulfate and to digestion with endo-beta-galactosidase. These results suggest widespread occurrence of a proteoglycan or sulfated glycoprotein bearing keratan sulfate-like carbohydrate and a core protein resembling that of corneal keratan sulfate proteoglycan
Percolative Effects on Noise in Pentacene Transistors
The 1/f noise in pentacene thin film transistors has been measured as a
function of device thickness from well above the effective conduction channel
thickness to only two conducting layers. Over the entire thickness range, the
spectral noise form is 1/f, and the noise parameter varies as (gate voltage)-1,
confirming that the noise is due to mobility fluctuations, even in the thinnest
films. Hooge's parameter varies as an inverse power-law with conductivity for
all film thicknesses. The magnitude and transport characteristics of the
spectral noise are well explained in terms of percolative effects arising from
the grain boundary structure.Comment: 13 pages, 4 figures, Publishe
Spot the match â wildlife photo-identification using information theory
BACKGROUND: Effective approaches for the management and conservation of wildlife populations require a sound knowledge of population demographics, and this is often only possible through mark-recapture studies. We applied an automated spot-recognition program (I(3)S) for matching natural markings of wildlife that is based on a novel information-theoretic approach to incorporate matching uncertainty. Using a photo-identification database of whale sharks (Rhincodon typus) as an example case, the information criterion (IC) algorithm we developed resulted in a parsimonious ranking of potential matches of individuals in an image library. Automated matches were compared to manual-matching results to test the performance of the software and algorithm. RESULTS: Validation of matched and non-matched images provided a threshold IC weight (approximately 0.2) below which match certainty was not assured. Most images tested were assigned correctly; however, scores for the by-eye comparison were lower than expected, possibly due to the low sample size. The effect of increasing horizontal angle of sharks in images reduced matching likelihood considerably. There was a negative linear relationship between the number of matching spot pairs and matching score, but this relationship disappeared when using the IC algorithm. CONCLUSION: The software and use of easily applied information-theoretic scores of match parsimony provide a reliable and freely available method for individual identification of wildlife, with wide applications and the potential to improve mark-recapture studies without resorting to invasive marking techniques
The photonâinduced reactions of chemisorbed CH<sub>3</sub>Br on Pt{111}
The photochemistry of chemisorbed CH3Br on Pt{111} has been investigated using high resolution electron energy loss spectroscopy (HREELS) and thermal desorption. The primary photonâinduced reaction involves the cleavage of the CâBr bond, giving rise to chemisorbed CH3 and Br, both of which can be identified in HREELS. From the angular dependence of the loss peaks, the symmetry of the CH3 surface complex is shown to be C3v. HBr can also be identified in subsequent thermal desorption. Experiments performed directly with HBr on Pt{111} indicate that molecular HBr adsorbs dissociatively on this surface. This result, in combination with observations of the CâH vibrational mode as a function of temperature, shows that the production of HBr arises from a secondary surface reaction between Br and CHx fragments. Based on the wavelength dependence of the fragmentation cross section and the photoemission spectrum of adsorbed CH3Br the primary photonâinduced reaction to a charge transfer excitation is ascribed
PPARα contributes to protection against metabolic and inflammatory derangements associated with acute kidney injury in experimental sepsis
Abstract Sepsisâassociated acute kidney injury (AKI) is a significant problem in critically ill children and adults resulting in increased morbidity and mortality. Fundamental mechanisms contributing to sepsisâassociated AKI are poorly understood. Previous research has demonstrated that peroxisome proliferatorâactivated receptor α (PPARα) expression is associated with reduced organ system failure in sepsis. Using an experimental model of polymicrobial sepsis, we demonstrate that mice deficient in PPARα have worse kidney function, which is likely related to reduced fatty acid oxidation and increased inflammation. Ultrastructural evaluation with electron microscopy reveals that the proximal convoluted tubule is specifically injured in septic PPARα deficient mice. In this experimental group, serum metabolomic analysis reveals unanticipated metabolic derangements in tryptophanâkynurenineâNAD+ and pantothenate pathways. We also show that a subgroup of children with sepsis whose genomeâwide expression profiles are characterized by repression of the PPARα signaling pathway has increased incidence of severe AKI. These findings point toward interesting associations between sepsisâassociated AKI and PPARαâdriven fatty acid metabolism that merit further investigation
The Zipf law for random texts with unequal probabilities of occurrence of letters and the Pascal pyramid
We model the generation of words with independent unequal probabilities of
occurrence of letters. We prove that the probability of occurrence of
words of rank has a power asymptotics. As distinct from the paper published
earlier by B. Conrad and M. Mitzenmacher, we give a brief proof by elementary
methods and obtain an explicit formula for the exponent of the power law.Comment: 4 page
A survey of weather information possessed by thirty-two pupils randomly selected from sixth and eleventh grades and from special classes
Thesis (Ed.M.)--Boston Universit
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