Preschool children's mathematical knowledge: The effect of teacher "math talk."

This study examined the relation between the amount of mathematical input in the speech of preschool or day-care teachers and the growth of children's conventional mathematical knowledge over the school year. Three main findings emerged. First, there were marked individual differences in children's conventional mathematical knowledge by 4 years of age that were associated with socioeconomic status. Second, there were dramatic differences in the amount of math-related talk teachers provided. Third, and most important, the amount of teachers' math-related talk was significantly related to the growth of preschoolers' conventional mathematical knowledge over the school year but was unrelated to their math knowledge at the start of the school year. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Estimation of effect size from a series of independent experiments.

Extends statistical theory for procedures based on the Glass estimator of effect size for methods used in the quantitative synthesis of research. An unbiased estimator of effect size is given. A weighted estimator of effect size based on data from several experiments is defined and shown to be optimal (asymptotically efficient). An approximate (large-sample) test for homogeneity of effect size across experiments is also given. The results of an empirical sampling study show that the large-sample distributions of the weighted estimator and the homogeneity statistic are quite accurate when the experimental and control group sample sizes exceed 10 and the effect sizes are smaller than about 1.5. (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Direct dating of archaeological pottery by compound-specific 14C analysis of preserved lipids

A methodology is described demonstrating the utility of the compound-specific 14C technique as a direct means of dating archaeological pottery. The method uses automated preparative capillary gas chromatography employing wide-bore capillary columns to isolate individual compounds from lipid extracts of archaeological potsherds in high purity (>95%) and amounts (>200 microg) sufficient for radiocarbon dating using accelerator mass spectrometry (AMS). A protocol was developed and tested on n-alkanes and n-carboxylic acids possessing a broad range of 14C ages. Analytical blanks and controls allowed background 14C measurements to be assessed and potential sources of errors to be detected, i.e., contamination with modern or dead 14C, isotopic fraction effects, etc. A "Russian doll" method was developed to transfer isolated target compounds onto tin powder/capsules prior to combustion and AMS analyses. The major advantage of the compound-specific technique is that 14C dates obtained for individual compounds can be directly linked to the commodities processed in the vessels during their use, e.g., animal fats. The compound-specific 14C dating protocol was validated on a suite of ancient pottery whose predicted ages spanned a 5000-year date range. Initial results indicate that meaningful correlations can be obtained between the predicted date of pottery and that of the preserved lipids. These findings constitute an important step forward to the direct dating of archaeological pottery.     

Why do categories affect stimulus judgment?

The authors tested a model of category effects on stimulus judgment. The model holds that the goal of stimulus judgment is to achieve high accuracy. For this reason, people place inexactly represented stimuli in the context of prior information, captured in categories, combining inexact fine-grain stimulus values with prior (category) information. This process can be likened to a Bayesian statistical procedure designed to maximize the average accuracy of estimation. If people follow the proposed procedure to maximize accuracy, their estimates should be affected by the distribution of instances in a category. In the present experiments, participants reproduced one-dimensional stimuli. Different prior distributions were presented. The experiments verified that people's stimulus estimates are affected by variations in a prior distribution in such a manner as to increase the accuracy of their stimulus reproductions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Critical Evaluation of Interlaboratory Data on Total,Elemental, and Isotopic Carbon in the Carbonaceous Particle Reference Material,NIST SRM 1649a

Because of increased interest in the marine and atmospheric sciences in elemental carbon (EC), or black carbon (BC) or soot carbon (SC), and because of the difficulties in analyzing or even defining this pervasive component of particulate carbon, it has become quite important to have appropriate reference materials for intercomparison and quality control. The NIST “urban dust” Standard Reference Material^® SRM 1649a is useful in this respect, in part because it comprises a considerable array of inorganic and organic species, and because it exhibits a large degree of (¹⁴C) isotopic heterogeneity, with biomass carbon source contributions ranging from about 2 % (essentially fossil aliphatic fraction) to about 32 % (polar fraction).A primary purpose of this report is to provide documentation for the new isotopic and chemical particulate carbon data for the most recent (31 Jan. 2001) SRM 1649a Certificate of Analysis. Supporting this is a critical review of underlying international intercomparison data and methodologies, provided by 18 teams of analytical experts from 11 institutions. Key results of the intercomparison are: (1) a new, Certified Value for total carbon (TC) in SRM 1649a; (2) ¹⁴C Reference Values for total carbon and a number of organic species, including for the first time 8 individual PAHs; and (3) elemental carbon (EC) Information Values derived from 13 analytical methods applied to this component. Results for elemental carbon, which comprised a special focus of the intercomparison, were quite diverse, reflecting the confounding of methodological-matrix artifacts, and methods that tended to probe more or less refractory regions of this universal, but ill-defined product of incomplete combustion. Availability of both chemical and ¹⁴C speciation data for SRM 1649a holds great promise for improved analytical insight through comparative analysis (e.g., fossil/biomass partition in EC compared to PAH), and through application of the principle of isotopic mass balance.     

Meta-analysis of screening and diagnostic tests.

Screening and diagnostic tests are common in the fields of psychology, medicine, and education. Often there are several competing tests, and decisions must be made about the relative accuracy of those tests. This article describes a general measure that can be used for both continuous and dichotomous outcome measures. It is the standardized distance between the means of the 2 populations. For continuous measures, it is the effect size measure. For dichotomous measures, it is proportional to the logarithm of the odds of the sensitivity plus the logarithm of the odds of the specificity. The measure is easily computed for both kinds of outcomes. Properties of this measure are discussed, and examples are given. The use of this measure to compare the average performance of different tests is described. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Detection of antibodies to equine arteritis virus by enzyme linked immunosorbant assays utilizing G(L), M and N proteins expressed from recombinant baculoviruses

On the experience of 73 patients, the authors state their guidelines on the treatment of bone metastases on the cervical spine. Most of the cases on which no vertebral collapse occur neither neurological deficit, radiation therapy and external support are suggested. Surgery is necessary on case of severe bone destruction, collapse with or without subsequent neurological impairment. Anterior excision is considered the best approach, sometimes complemented by posterior stabilisation.     

Higher-level snake phylogeny inferred from mitochondrial DNA sequences of 12S rRNA and 16S rRNA genes

N-Nitrosomethylbenzylamine (NMBA) is a potent esophagus-specific carcinogen that has been utilized extensively in the study of esophageal carcinogenesis in rats. While many studies have focused on the pathogenesis of NMBA-induced esophageal tumors, the tumorigenicity of NMBA itself has not been thoroughly investigated in any single, systematic dose-response study. Therefore, in this study we evaluated NMBA tumorigenicity in rats following various short-term s.c. treatment regimens with the aim of developing an abbreviated treatment protocol which could be used in future studies. To assess the possible correlation of basal cell proliferation with NMBA tumorigenicity, we evaluated the expression of proliferating cell nuclear antigen (PCNA) in both control and NMBA-treated rats. In rats which received a cumulative NMBA dosage of 7.5 mg/kg over the course of 5 weeks, tumor incidence and multiplicity were as follows: 40% with 0.4 +/- 0.3 tumors/rat at week 10; 100% with 2.2 +/- 1.0 tumors/rat at week 20; and 100% with 2.3 +/- 1.0 tumors/rat at week 30. These rats exhibited marked increases in basal cell labeling, with indices that were 1.5- to 1.8-fold higher than controls. NMBA treatment regimens of shorter duration with equivalent or higher cumulative dosages were generally ineffective in producing esophageal tumors, even though significantly elevated levels of basal cell proliferation occurred. Together, these findings indicate that the duration of NMBA treatment is of critical importance in the tumorigenic potential of the carcinogen.