Global Comparison (global + comparison)

Distribution by Scientific Domains

Selected Abstracts

Decalcification of root canal dentine by citric acid, EDTA and sodium citrate

L. F. Machado-Silveiro
Abstract Aim, To measure the demineralization capability of 1 and 10% citric acid, 10% sodium citrate and 17% EDTA during immersions of 5, 10 and 15 min on root canal dentine. Methodology, Crowns were sectioned from eight maxillary canines. The cementum was removed from the cervical third of the roots to expose the dentine. Canals were prepared using a handpiece-mounted Largo Peeso reamer. A 3-mm thick cross-sectional slice was obtained from the cervical third of each root. Each slice was sectioned into four equal parts. These specimens were assigned to one of four groups (n = 8) for the application of 1% citric acid, 10% citric acid, 10% sodium citrate or 17% EDTA. Each specimen underwent three successive 5-min immersions in each solution at room temperature. The solutions were not renewed between immersions. Two millimetres of solution were collected from the extracts and lanthanum oxide was added for the calcium reading by spectrophotometry. To compare the amounts of calcium removed by each solution, the Friedman test was used for the global comparison and the Wilcoxon test for paired comparisons. Differences between groups were evaluated using the Kruskal,Wallis test for the global comparison and Mann,Whitney test for paired comparisons. Results, Overall, 1 and 10% citric acid were more effective than EDTA or sodium citrate at the three immersion times (P < 0.001); 10% citric acid was more effective than 1% citric acid (P < 0.001). EDTA and 1 and 10% citric acid showed decreasing effectiveness with time, and the decrease was significant for citric acid at both concentrations (P < 0.001). Although sodium citrate removed little calcium during the three time periods, the small increase recorded was significant (P < 0.01). Conclusions, Citric acid at 10% was the most effective decalcifying agent, followed by 1% citric acid, 17% EDTA and 10% sodium citrate. [source]

Building assets from birth: a global comparison of Child Development Account policies

Vernon Loke
Asset building is a growing theme in public policy, and building assets from birth in the form of Child Development Accounts is now occurring in several countries. This article provides an overview of the Child Development Account policies in Singapore, Canada, the UK and Korea, and the proposed policy in the USA. The key elements of inclusiveness, progressivity, coherence and integration, and development are explicated and discussed. [source]

Quantitative proteomics of intracellular Porphyromonas gingivalis

Qiangwei Xia
Abstract Whole-cell quantitative proteomic analyses were conducted to investigate the change from an extracellular to intracellular lifestyle for Porphyromonas gingivalis, a Gram-negative intracellular pathogen associated with periodontal disease. Global protein abundance data for P. gingivalis strain ATCC 33277 internalized for 18,h within human gingival epithelial cells and controls exposed to gingival cell culture medium were obtained at sufficient coverage to provide strong evidence that these changes are profound. A total of 385 proteins were overexpressed in internalized P. gingivalis relative to controls; 240 proteins were shown to be underexpressed. This represented in total about 28% of the protein encoding ORFs annotated for this organism, and slightly less than half of the proteins that were observed experimentally. Production of several proteases, including the classical virulence factors RgpA, RgpB, and Kgp, was decreased. A separate validation study was carried out in which a 16-fold dilution of the P. gingivalis proteome was compared to the undiluted sample in order to assess the quantitative false negative rate (all ratios truly alternative). Truly null (no change) abundance ratios from technical replicates were used to assess the rate of quantitative false positives over the entire proteome. A global comparison between the direction of abundance change observed and previously published bioinformatic gene pair predictions for P. gingivalis will assist with future studies of P. gingivalis gene regulation and operon prediction. [source]

Race and global patterns of phenotypic variation

John H. Relethford
Abstract Phenotypic traits have been used for centuries for the purpose of racial classification. Developments in quantitative population genetics have allowed global comparison of patterns of phenotypic variation with patterns of variation in classical genetic markers and DNA markers. Human skin color shows a high degree of variation among geographic regions, typical of traits that show extensive natural selection. Even given this high level of geographic differentiation, skin color variation is clinal and is not well described by discrete racial categories. Craniometric traits show a level of among-region differentiation comparable to genetic markers, with high levels of variation within populations as well as a correlation between phenotypic and geographic distance. Craniometric variation is geographically structured, allowing high levels of classification accuracy when comparing crania from different parts of the world. Nonetheless, the boundaries in global variation are not abrupt and do not fit a strict view of the race concept; the number of races and the cutoffs used to define them are arbitrary. The race concept is at best a crude first-order approximation to the geographically structured phenotypic variation in the human species. Am J Phys Anthropol 2009. 2009 Wiley-Liss, Inc. [source]

Transit peptide diversity and divergence: A global analysis of plastid targeting signals

BIOESSAYS, Issue 10 2007
Nicola J. Patron
Proteins are targeted to plastids by N-terminal transit peptides, which are recognized by protein import complexes in the organelle membranes. Historically, transit peptide properties have been defined from vascular plant sequences, but recent large-scale genome sequencing from the many plastid-containing lineages across the tree of life has provided a much broader representation of targeted proteins. This includes the three lineages containing primary plastids (plants and green algae, rhodophytes and glaucophytes) and also the seven major lineages that contain secondary plastids, "secondhand" plastids derived through eukaryotic endosymbiosis. Despite this extensive spread of plastids throughout Eukaryota, an N-terminal transit peptide has been maintained as an essential plastid-targeting motif. This article provides the first global comparison of transit peptide composition and summarizes conservation of some features, the loss of an ancestral motif from the green lineages including plants, and modifications to transit peptides that have occurred in secondary and even tertiary plastids. BioEssays 29:1048,1058, 2007. 2007 Wiley Periodicals, Inc. [source]

Beyond ,Gender Differences': A Canadian Study of Women's and Men's Careers in Engineering

Gillian Ranson
This article explores the relationship between gender and career paths for a group of women and men who graduated as engineers during a period of labour market turbulence in western Canada during the 1980s. Using a model adapted from Brown (1982), the article uses ,career path' as a device to organize data drawn primarily from telephone and face-to-face interviews with 317 graduates. Three career paths provide the focus for the study: the ,organizational', characterized by stable employment with one employer; the ,occupational', characterized by mobility between employers; and the entrepreneurial, characterized by self-employment. The use of the career path framework moves the study beyond global comparisons (of the dichotomized ,gender differences' kind) between ,the women' and ,the men'. As well as allowing for comparison between the paths, it allows more refined and contextualized comparisons within each path. Such comparisons produce patterns of similarity and difference that sometimes transcend gender. [source]