The chain pyramid: hierarchical contour processing

A novel hierarchical approach toward fast parallel processing of chain-codable contours is presented. The environment, called the chain pyramid, is similar to a regular nonoverlapping image pyramid structure. The artifacts of contour processing on pyramids are eliminated by a probabilistic allocation algorithm. Building of the chain pyramid is modular, and for different applications new algorithms can be incorporated. Two applications are described: smoothing of multiscale curves and gap bridging in fragmented data. The latter is also employed for the treatment of branch points in the input contours. A preprocessing module allowing the application of the chain pyramid to raw edge data is also described. The chain pyramid makes possible fast, O[log(image_-size)], computation of contour representation in discrete scale-space     

Queue Lengths and Waiting Times for Multiserver Queues with Abandonment and Retrials

We consider a Markovian multiserver queueing model with time dependent parameters where waiting customers may abandon and subsequently retry. We provide simple fluid and diffusion approximations to estimate the mean, variance, and density for both the queue length and virtual waiting time processes arising in this model. These approximations, which are generated by numerically integrating only 7 ordinary differential equations, are justified by limit theorems where the arrival rate and number of servers grow large. We compare our approximations to simulations, and they perform extremely well.     

Graphbots: cooperative motion planning in discrete spaces

Most previous theoretical work on motion planning for a group of robots has addressed the problem of path planning for the individual robots sequentially, in geometrically simple regions of Euclidean space (e.g. a planar region containing polygonal obstacles). In this paper, we define a version of the motion-planning problem in which the robots move simultaneously. We establish conditions under which a team of robots having a particular configuration can move from any start location to any goal destination in a graph-structured space. We show that, for a group of robots that maintain a fixed formation, we can find the “shortest” path in polynomial time, and we give faster algorithms for special kinds of environments     

Substantial narrowing of the Niemann-Pick C candidate interval by yeast artificial chromosome complementation

Niemann-Pick disease type C (NP-C) is an autosomal recessive lipidosis linked to chromosome 18q11-12, characterized by lysosomal accumulation of unesterified cholesterol and delayed induction of cholesterol-mediated homeostatic responses. This cellular phenotype is identifiable cytologically by filipin staining and biochemically by measurement of low-density lipoprotein-derived cholesterol esterification. The mutant Chinese hamster ovary cell line (CT60), which displays the NP-C cellular phenotype, was used as the recipient for a complementation assay after somatic cell fusions with normal and NP-C murine cells suggested that this Chinese hamster ovary cell line carries an alteration(s) in the hamster homolog(s) of NP-C. To narrow rapidly the candidate interval for NP-C, three overlapping yeast artificial chromosomes (YACs) spanning the 1 centimorgan human NP-C interval were introduced stably into CT60 cells and analyzed for correction of the cellular phenotype. Only YAC 911D5 complemented the NP-C phenotype, as evidenced by cytological and biochemical analyses, whereas no complementation was obtained from the other two YACs within the interval or from a YAC derived from chromosome 7. Fluorescent in situ hybridization indicated that YAC 911D5 was integrated at a single site per CT60 genome. These data substantially narrow the NP-C critical interval and should greatly simplify the identification of the gene responsible in mouse and man. This is the first demonstration of YAC complementation as a valuable adjunct strategy for positional cloning of a human gene.     

Prediction of sensory quality by near infrared reflectance analysis of frozen and freeze dried green peas (Pisum sativum)

Frozen, green peas (Pisum sativum L ) of different varieties and different levels of maturity were evaluated by sensory analysis using a panel of ten trained judges. Two texture variables (hardness and mealiness) and four flavour variables (pea flavour, sweetness, fruity flavour, off flavour) were considered. Near infiared reflectance ( N I R ) analysis was performed with the same material, on both the fiozen and fieeze dried peas. The N I R instrument was calibrated to predict the sensory variables using the multivariate analytical method of principal component regression. Tenderometer readings of the same peas were also calibrated to predict the sensory variables. N I R analysis on the fieeze dried peas showed relative ability of prediction (RAP) values for the sensory variables which were higher than those for the tenderometer readings. The sensory attributes pea flavour and hardness were predicted with higher RAP values by tenderometer readings than by N I R analysis on fiozen peas. For the rest of the attributes, N I R analysis on fiozen peas gave higher RAP values than tenderometer readings. N I R generally gave high RAP values, and this tentative study suggests that N I R analysis could be a useful tool in instrumentally assessing the quality of frozen peas.     

Newcasters' facial expressions and voting behavior of viewers: Can a smile elect a president?

Two studies examined the association between newscasters' facial expressions and the voting behavior of viewers. In Exp I, with 45 undergraduates, the facial expressions exhibited by network newscasters while referring to the 1984 presidential candidates prior to the election were investigated. Results indicate that 1 of the 3 newscasters exhibited significantly more positive facial expressions when referring to Reagan than when referring to Mondale. In Exp II, a telephone survey of approximately 200 individuals was conducted to determine whether voting behavior was associated with the nightly news program watched. It was found that voters who regularly watched the newscaster who exhibited the biased facial expressions were significantly more likely to vote for the candidate that the newscaster had smiled upon. Three explanations for the results are discussed: (1) Viewing the newscasters' biased facial expressions caused the viewers' voting preferences; (2) the viewers' voting preferences determined their viewing of biased newscasters' facial expressions; or (3) some other variable accounted for the findings. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thermoluminescence solid-state nanodosimetry--the peak 5A/5 dosemeter

The shape of composite peak 5 in the glow curve of LiF:Mg,Ti (TLD-100) following (90)Sr/(90)Y beta irradiation, previously demonstrated to be dependent on the cooling rate used in the 400°C pre-irradiation anneal, is shown to be dependent on ionisation density in both naturally cooled and slow-cooled samples. Following heavy-charged particle high-ionisation density (HID) irradiation, the temperature of composite peak 5 decreases by ～5°C and the peak becomes broader. This behaviour is attributed to an increase in the relative intensity of peak 5a (a low-temperature satellite of peak 5). The relative intensity of peak 5a is estimated using a computerised glow curve deconvolution code based on first-order kinetics. The analysis uses kinetic parameters for peaks 4 and 5 determined from ancillary measurements resulting in nearly 'single-glow peak' curves for both the peaks. In the slow-cooled samples, owing to the increased relative intensity of peak 5a compared with the naturally cooled samples, the precision of the measurement of the 5a/5 intensity ratio is found to be ～15% (1 SD) compared with ～25% for the naturally cooled samples. The ratio of peak 5a/5 in the slow-cooled samples is found to increase systematically and gradually through a variety of radiation fields from a minimum value of 0.13±0.02 for (90)Sr/(90)Y low-ionisation density irradiations to a maximum value of ～0.8 for 20 MeV Cu and I ion HID irradiations. Irradiation by low-energy electrons of energy 0.1-1.5 keV results in values between 1.27 and 0.95, respectively. The increasing values of the ratio of peak 5a/5 with increasing ionisation density demonstrate the viability of the concept of the peak 5a/5 nanodosemeter and its potential in the measurement of average ionisation density in a 'nanoscopic' mass containing the trapping centre/luminescent centre spatially correlated molecule giving rise to composite peak 5.     

Solar energy transmittance of translucent samples: A comparison between large and small integrating sphere measurements

Optical transmittance and reflectance of a translucent plastic PTFE film have been measured over the solar wavelength range using different integrating spheres. The same sample has been measured with small and large spheres and the total solar transmittance has been obtained from both broad band measurements and from integration of spectral data. The fact that the sum of reflectance and transmittance often exceeds 100% shows that all types of spheres tend to overestimate the transmittance of this highly scattering sample. This error can be attributed to the sphere geometry in combination with the light scattering properties of the sample, and unless proper correction of recorded data is carried out the error may be as large as 5–10%. Some specific errors are presented and an approximate correction procedure is suggested.These results show that there is a need for a transmittance standard which can be used to calibrate integrating spheres. Such a standard with negligible thickness would be especially useful for measurements with large, broadband integrating spheres, but would also be helpful for the correct handling of data from small spectral instruments.