A linkage map of human chromosome 21:43 PCR markers at average intervals of 2.5 cM

A genetic linkage map of human chromosome 21q (HC21q) containing 43 markers genotyped by the polymerase chain reaction in the CEPH pedigrees is presented. The markers placed on this map are highly polymorphic with an average heterozygosity of 61%. The average interval size of the markers localized at 1000:1 odds is 2.5 cM. The map has a total length of 65.5 cM, with male and female lengths of 47.7 and 83.3 cM, respectively. The genotypes used in the construction of this map were subjected to rigorous error checking, which is reflected in the shorter map length compared to previous maps; the estimated error rate in genotyping is less than 0.04%. As noted in previous linkage maps there is increased recombination in females on proximal HC 21q and in the male in a region near the telomere. This map of HC 21 represents a highly informative and dense meiotic linkage map and will be useful in linking disease phenotypes to loci on this chromosome.     

A numerical model for single screw extrusion with poly(vinyl chloride) (PVC) resins

A computer model has been developed to simulate the behavior of molten polymer in the melt conveying zone of extruders. This model, based on a hybrid finite difference/finite element resolution of the equations of change governing momentum and heat transfer, allows the prediction of the pressure profile while accounting for wall end effects as well as the solid bed velocity. Simulation results are compared with analytical and finite difference method results found in the literature. A fairly good agreement is obtained in the case of low density polyethylene. Numerical tests are also carried out with rigid poly(vinyl chloride) compound used for window profile extrusion. The good agreement found between the predictions and experimental measurements obtained on an industrial extruder confirms the performance of the proposed model.     

Determining subsea permafrost characteristics with a cone penetrometer — Prudhoe Bay,Alaska

Sediments beneath the Beaufort Sea near Prudhoe Bay, Alaska, were probed at 27 sites using a static cone penetrometer to determine engineering properties and distribution of material types, including ice-bonded sediments. The probe, designed and constructed at the Cold Regions Research and Engineering Laboratory, provided both point and casing resistance data and thermal profiles. At five sites these data were correlated with information from adjacent drilled and sampled holes. These control data and the quality of the probe information permitted profiles of sediment type and occurrence of ice-bonded material to be developed along three lines that included various geological features and depositional environments.Material properties were quite variable in the upper 14 m of sediments probed. In general, softer, finer-grained sediments occurred in the upper layers, while penetration refusal was met in stiff gravels 10 to 12 m below the seabed.Seabed temperatures during the study were all below 0°C. However, because of uncertainties in freezing point values caused by brines, evaluation of the penetration resistance data was required to identify the occurrence of ice-bonded sediments. The coupling of thermal and penetration resistance data revealed that seasonally ice-bonded sediments occurred where the sea ice froze back to or near the seabed. Deeper, perennially frozen sediments also appeared to be present at several probe sites.     

Effect of boron on the structural and electrochemical properties of nanocrystalline Ti2RuFeBx electrodes

The effect of the boron content on the structural and electrochemical properties of nanocrystalline Ti₂RuFeB_x (with x varying from 0 to 12) was studied. The nanocrystalline materials were prepared by high energy ball milling and their structural evolution was analyzed by X-ray and neutron diffraction. Through a detailed Rietveld refinement analysis of the structural data, it is shown that the nanocrystalline materials are mainly composed of a B2 structure at low boron content (0 < x < 2). At higher boron content, TiB₂ is mainly formed and the B2 structure disappears with the concurrent formation of a highly disordered Ru-rich phase. These electrodes were tested for the hydrogen evolution reaction in both NaOH and chlorate solutions. The best results are obtained for 4 ≤ x ≤ 6, with a cathodic overpotential at −250 mA/cm², η₂₅₀, of ∼−575 mV. Accelerated aging tests and continuous electrolysis tests show that η₂₅₀ does not vary with time, contrary to the case of Ti₂RuFe, which shows a rapid deterioration of the cathodic overpotential after a few hours of continuous electrolysis. This is explained by the lower solubility of hydrogen in Ti₂RuFeB₄ as opposed to Ti₂RuFe.     

Review of Resistive Force Models for Earthmoving Processes

The force required to insert a tool into a medium is of major interest for the design and automation of earthmoving machinery. The present work reviews previous investigations on forces encountered during earthmoving processes by cyclic (but nonrotary) excavation machines. The objective is to integrate the formulation for cutting and penetrating forces to those for excavation. Common practices for characterizing an unfrozen medium and the associated tool actions are discussed, followed by a general overview of various models describing earthmoving tasks of penetration, cutting, and excavation. Observation and analysis of cutting and excavation models reveals that there is not a common ground for their validation, but it also identifies a core of key parameters, reduced in number and essential to any further excavation model. The paper suggests a normalized experimental verification and comparison of the models before they can be further used.     

Temporally massed CS presentations generate more fear extinction than spaced presentations.

Rodent fear conditioning models both excitatory learning and the pathogenesis of human anxiety, whereas extinction of conditional fear is a paradigm of inhibitory learning and the explicit model for behavior therapy. Many studies support a general learning rule for acquisition: Temporally spaced training is more effective than massed training. The authors asked whether this rule applies to extinction of conditional fear in mice. The authors find that both short- and long-term fear extinction are greater with temporally massed presentations of the conditional stimulus (CS). The data also indicate that once CS presentations are sufficiently massed to initiate, or "induce," extinction learning, further CS presentations are more effective when spaced. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of arm proprioception in calibrating the arm-eye temporal coordination

When subjects track with the eyes an arm-attached target, eye latency is shorter than when tracking an external target. This improved synchrony could result from either a common command addressed to the two systems or from an influence of the arm command on eye motion initiation. According to the first hypothesis, the eyes should start moving long before the arm, because of the difference in dynamics. We recorded arm and eye motion together with biceps muscle activity in controls and a deafferented subject. Data support the second hypothesis. Moreover, the deafferented subject showed a lesser correlation between arm and eye motions than controls, suggesting a role for arm proprioception in the calibration of the temporal relationship between arm and eye movements.     

Body-image disturbances in bulimia nervosa: Influences of actual body size.

This study evaluated body-image distortion and ideal body-size preferences in 423 nonbulimic women and 108 bulimics. Analyses of covariance were utilized to compare the bulimic and nonbulimic groups on measures of current and ideal body size. Weight was used as a covariate to evaluate the influence of actual body size on perception of current body size and selection of ideal body size. Bulimics chose current body sizes that were significantly larger than those picked by nonbulimics regardless of actual body size. Bulimics also chose thinner ideal body sizes than did nonbulimics, regardless of actual body size. These results suggest that body-image distortion and extreme preference for thinness are a fundamental characteristic of bulimia nervosa. These results were discussed in terms of how perception of a large body size and preference for a very thin body size might interact to produce a high degree of dissatisfaction and overconcern with body size in bulimia nervosa. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of oral ritodrine on maternal and fetal carbohydrate metabolism

The reported growth-promoting effects of the beta-sympathomimetic compound, ritodrine, have been investigated. The carbohydrate tolerance of eight pregnant women was found to be unaffected by treatment with oral ritodrine over a ten-week period. A further observation that the carbohydrate metabolism of the newborn infants of these women was within normal limits tends to discount possibility that any growth-promoting action ritodrine may have on the fetus is mediated through a diabetogenic effect on the mother.