Age of acquisition: Its neural and computational mechanisms.

The acquisition of new skills over a life span is a remarkable human ability. This ability, however, is constrained by age of acquisition (AoA); that is, the age at which learning occurs significantly affects the outcome. This is most clearly reflected in domains such as language, music, and athletics. This article provides a perspective on the neural and computational mechanisms underlying AoA in language acquisition. The authors show how AoA modulates both monolingual lexical processing and bilingual language acquisition. They consider the conditions under which syntactic processing and semantic processing may be differentially sensitive to AoA effects in second-language acquisition. The authors conclude that AoA effects are pervasive and that the neural and computational mechanisms underlying learning and sensorimotor integration provide a general account of these effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experiments of Fast Learning with High Order Boltzmann Machines

This work reports the results obtained with the application of High Order Boltzmann Machines without hidden units to construct classifiers for some problems that represent different learning paradigms. The Boltzmann Machine weight updating algorithm remains the same even when some of the units can take values in a discrete set or in a continuous interval. The absence of hidden units and the restriction to classification problems allows for the estimation of the connection statistics, without the computational cost involved in the application of simulated annealing. In this setting, the learning process can be sped up several orders of magnitude with no appreciable loss of quality of the results obtained.     

2-Hydroxypropyl-beta-cyclodextrin enhances phorbol ester effects on glucose transport and/or protein kinase C-beta translocation to the plasma membrane in rat adipocytes and soleus muscles

In rat adipocytes and soleus muscles, 2-hydroxypropyl-beta-cyclodextrin (CD) was found to have a relatively small or no effect on basal or insulin-stimulated hexose uptake, but markedly enhanced hexose uptake effects of phorbol esters and/or diacylglycerol. In rat adipocytes, the CD-induced enhancement of hexose uptake during concurrent phorbol ester treatment was not associated with an increase in GLUT4 glucose transporter translocation to the plasma membrane, which was stimulated comparably by insulin and phorbol esters. Moreover, CD appeared to activate or facilitate the activation of glucose transporters subsequent to their translocation to the plasma membrane during ongoing phorbol ester treatment. In rat adipocytes, CD also enhanced the translocation of protein kinase C (PKC)-beta to the plasma membrane during the action of phorbol esters, which alone had little or no effect on this specific PKC translocation. Although it is uncertain how CD alters the function of plasma membranes to enhance the translocation of PKC-beta to, and the activation of glucose transporters within, this subcellular fraction during phorbol ester treatment, our findings provide direct support for a two-step model in the activation of glucose transport. In addition, it seems clear that, at least in some cell types, simple phorbol ester treatment does not necessarily serve as a ubiquitous activator of all activable PKC pools and all potential PKC-mediated responses.     

Electrical heat tracing: international harmonization-now and in thefuture

In the past, electrical heat tracing has been thought of as a minor addition to plant utilities. Today, it is recognized as a critical subsystem to be monitored and controlled. A marriage between process, mechanical, and electrical engineers must take place to ensure that optimum economic results are produced. The Internet, expert systems, and falling costs of instrumentation will all contribute to more reliable control systems and improved monitoring systems. There is a harmonization between Europe and North America that should facilitate design and installation using common components. The future holds many opportunities to optimize the design     

Controlled-Release Matrix of Acetaminophen-Ethylcellulose Solid Dispersion

In this study ethylcellulose was evaluated as a carrier for preparation of prolonged release acetaminophen tablets. Solid dispersions containing three levels of ethylcellulose and acetaminophen (1:3; 1:1; 3:1) were prepared by the solvent method. Also physical mixtures at the same level of ethylcellulose and acetaminophen were prepared. Systems composed of solid dispersion or physical mixture containing the equivalent weight of 50 mg acetaminophen, Lactose fast-flo as diluent and 1% magnesium stearate as lubricant were compressed into tablets and tested for dissolution. The dissolution data showed that the drug release decreased as the level of ethylcellulose increased in the solid dispersion formulations. The drug release from tablets prepared with solid dispersion followed the diffusion controlled model for inert porous matrix, while the drug release from tablets prepared with physical mixture followed the first-order kinetic model.     

High‐pressure processing effects on the mechanical,barrier and mass transfer properties of food packaging flexible structures: a critical review

Food products can be high‐pressure processed (HPP) either in bulk or prepackaged in flexible or semi‐rigid packaging materials. In the latter case the packaging material is subjected, together with the food, to high‐pressure treatment. A number of studies have been performed to quantify the effects of high‐pressure processing on the physical and barrier properties of the packaging material, since the integrity of the package during and after processing is of paramount importance to the safety and quality of the food product. This article reviews the results of published research concerning the effect of HPP on packaging materials. Copyright © 2004 John Wiley & Sons, Ltd.     

Role of adenine nucleotides in the activation of microsomal cholesterol ester hydrolase by fructose or adenosine in rat hepatocytes

The significance of the demonstration of a clonal B-cell population in gastric lymphoid infiltrates was investigated by analysis of immunoglobulin heavy chain (IgH) gene rearrangements using sensitive polymerase chain reactions, employing fluorescently labelled primers to target the FR3 and FR1 regions. Tissue blocks were studied showing different histological features (high-grade lymphoma, low-grade lymphoma, and chronic gastritis) from 12 gastrectomies for primary gastric lymphoma, together with blocks showing chronic gastritis from 13 cases of gastric adenocarcinoma and biopsies from 33 patients with active Helicobacter-associated chronic gastritis. Clonal IgH gene rearrangements were detected in lymphoma samples from eight of the gastrectomies for lymphoma (67 per cent). In four of these eight specimens, clonal rearrangements were also detectable in the samples showing only chronic gastritis. Three of 28 (11 per cent) informative biopsies showing active Helicobacter-associated chronic gastritis had detectable clonal populations. Clonal rearrangements were also demonstrated in two of eight (25 per cent) informative blocks showing chronic gastritis from eight gastrectomies for adenocarcinoma. It is concluded that the detection of a clonal population in a suspicious lymphoid infiltrate does not confirm the diagnosis of lymphoma, nor does the absence of such a population imply benignity.     

N dopant exponential profiles for silicon solar cells

A numerical model of solar cells is described, which provides optimum design rules for exponential N⁺ dopant profiles for heavily doped emitter regions. The model gives a useful insight into the relative impact of surface and bulk recombination on device performance. Results agree well with theorical models.     

Deletions and loss of expression of p16INK4a and p21Waf1 genes are associated with aggressive variants of mantle cell lymphomas

Mantle cell lymphoma (MCL) is molecularly characterized by bcl-1 rearrangement and cyclin D1 gene overexpression. Some aggressive variants of MCL have been described with blastic or large cell morphology, higher proliferative activity, and shorter survival. The cyclin-dependent kinase inhibitors (CDKIs) p21Waf1 and p16INK4a have been suggested as candidates for tumor-suppressor genes. To determine the role of p21Waf1 and p16INK4a gene alterations in MCLs, we examined the expression, deletions, and mutations of these genes in a series of 24 MCLs, 18 typical, and 6 aggressive variants. Loss of expression and/or deletions of p21Waf1 and p16INK4a genes were detected in 4 (67%) aggressive MCLs but in none of the typical variants. Two aggressive MCLs showed a loss of p16INK4a expression. These cases showed homozygous deletions of p16INK4a gene by Southern blot analysis. An additional aggressive MCL in which expression could not be examined showed a hemizygous 9p12 deletion. Loss of p21Waf1 expression at both protein and mRNA levels was detected in an additional aggressive MCL. No p21Waf1 gene deletions or mutations were found in this case. The p21Waf1 expression in MCLs was independent of p53 mutations. The two cases with p53 mutations showed p21Waf1 and p16INK4a expression whereas the 4 aggressive MCLs with p16INK4a and p21Waf1 gene alterations had a wild-type p53. p21Waf1 and p16INK4a were expressed at mRNA and protein levels in all typical MCLs examined. No gene deletions or point mutations were found in typical variants. Two typical MCLs showed an anomalous single-stranded conformation polymorphism corresponding to the known polymorphisms at codon 148 of p16INK4a gene and codon 31 of p21Waf1 gene. These findings indicate that p21Waf1 and p16INK4a alterations are rare in typical MCLs but the loss of p21Waf1 and p16INK4a expression, and deletions of p16INK4a gene are associated with aggressive variants of MCLs, and they occur in a subset of tumors with a wild-type p53 gene.