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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of prosthodontics 1 (1992), S. 0 
    ISSN: 1532-849X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Purpose In the American National Standards Institute/American Dental Association specification no. 19, compatibility of impression materials with dental stones is assessed by the presence of a 20μm-wide line reproduced on an unmodified calcium sulfate dihydrate cast. In actual dental practice, modified type IV dental stones are used, although little is known of their compatibility with polysulfide impression materials. This study evaluated the compatibility of 6 polysulfide impression materials and 11 modified type IV dental stones.Materials and Methods A line 20 μm wide was etched on four glass dies. Four samples of each combination of impression material and dental stone were prepared according to the manufacturer's directions with an additional 3 minutes for the final setting time. Compatibility was determined by the presence of the reproduced line on the dental stones, as observed under low angle 10 × magnification by four rater groups.Results The line was reproduced on all of the impression specimens, and the examiners recorded 66 positive identifications of the line on the stone casts out of a possible 1,056 ratings for a total of 6.25% of the specimens. Out of a possible 66 impression-stone combinations, only 18 reproduced the 20-μm line. The combinations reproducing the lines most frequently (75%) were Neoplex with Blue Die Stone (Columbus Dental, St Louis, MO) and Coeflex with Indic Die Stone (Coe Lab Inc, Chicago, IL).Conclusions The study showed that many combinations of polysulfide impression materials and modified type IV dental stones did not reproduce the 20-μm line; therefore, not every polysulfide is compatible with every type IV dental stone.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of prosthodontics 1 (1992), S. 0 
    ISSN: 1532-849X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Dental periodicals are the fundamental source of prosthodontic research. The ability to understand and contribute to dental literature is basic to the prosthodontic profession. The purpose of this study is to tally relative frequency with which various descriptive (n = 18), graphical (n = 7), and inferential statistical procedures (n = 68) are used in the prosthodontic literature. Our method consists of four procedures: journal selection, choice of 1987 through 1988 articles with inferential statistical content, tally of the statistical procedures in those articles, and quality control procedures used in obtaining these data. At least 50% of 10 prosthodontists selected 17 of 100 journals most likely to be read by prosthodontists. In the 17 journals, 1,320 articles were screened of which 406 were selected and evaluated for their statistical procedures. The bar and line plots were the most common graphical procedures occurring in over one fourth of the 406 articles. Percentages, means, and standard deviations occurred in more than 40%. Although 58% used the .05 significance level, only 0.3% mentioned power. Analysis of variance was used more often than the t tests (42%v 29%), whereas correlation/regression (21%) and chi-square tests (14%) were used less often. The t tests, analysis of variance (Duncan, Tukey, and Student-Newman-Keuls multiple comparison procedures), chi-square tests, correlation and regression, and the Wilcoxon tests occurred in at least 5% of the 406 articles.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Applied psychophysiology and biofeedback 17 (1992), S. 153-156 
    ISSN: 1573-3270
    Schlagwort(e): influential observations ; data analysis ; regression analysis ; statistics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A comment is made on an article recently published in this journal by Borgeat, Elie, and Castonguay (1991). It is noted that the raw data contained an outlier which is shown to have had a large influence on their estimation of the regression coefficient. Analysis of the data using a nonparametric statistic that is optimal for long-tailed distributions showed that the true regression coefficient is probably smaller than that reported. Other approaches to the analysis of data containing influential outliers are discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1573-3270
    Schlagwort(e): generalizability theory ; psychological stress ; psychophysiology ; surface electromyography ; tension-type headache
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Generalizability theory is an extension of classical reliability theory that allows multiple sources of measurement error in an experimental design to be investigated simultaneously. In the present study, generalizability theory was used to evaluate measurement error in psychophysiological test procedures used to differentiate tension headache patients from normal controls based upon measures of electromyographic (EMG) responding. Thirty-three subjects who met diagnostic criteria for tension-type headache and 40 normal control subjects who rarely or never experienced headache participated in two laboratory sessions. EMG activity of head and neck muscles was recorded while subjects performed baseline, relaxation, choice reaction time, psychomotor tracking, and cold pressor tasks. Variance components were computed for an experimental design having subjects nested within experimenters and crossed with sessions and replications. Generalizability coefficients were computed for combinations of various numbers of sessions and replications. The generalizability of EMG measures was highly variable, depending on the experimental conditions in force. The largest sources of measurement error were attributed to the unique responsiveness of individual subjects under a particular set of treatment conditions. For some stress tests currently in use, data from several testing sessions may need to be averaged in order to achieve acceptable levels of generalizability. Generalizability greater than 0.80 can be expected only rarely when data are collected during a single session. In the research setting, low generalizability may account for the failure of EMG-based stress tests to differentiate tension headache patients from controls during stressful task performance. In the clinical setting, the generalizability of information derived from “stress profiling” or muscle “scanning” techniques, which depend on results obtained during a single testing session, is doubtful.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Metabolic brain disease 5 (1990), S. 195-204 
    ISSN: 1573-7365
    Schlagwort(e): glucose ; dichloroacetate ; brain ; development ; lactate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Dichloroacetate (DCA) activates pyruvate dehydrogenase (PDH) by inhibiting PDH kinase. Neutralized DCA (100 mg/kg) or saline was intravenously administered to 20 to 25-day-old rats (50–75 g). Fifteen minutes later a mixture of [6−14C]glucose and [3H]fluorodeoxyglucose (FDG) was administered intravenously and the animals were sacrificed by microwave irradiation (2450 MHz, 8.0 kW, 0.6–0.8 sec) after 2 or 5 min. Brain regional rates of glucose use and metabolite levels were determined. DCA-treated rats had increased rates of glucose use in all regions studied (cortex, thalamus, striatum, and brain stem), with an average increase of 41%. Lactate levels were lower in all regions, by an average of 35%. There were no significant changes in levels of ATP, creatine phosphate, or glycogen in any brain region. Blood levels of lactate did not differ significantly between the DCA- and the saline-treated groups. Blood glucose levels were higher in the DCA group. In rats sacrificed by freeze-blowing, DCA treatment caused lower brain levels of both lactate and pyruvate. These results cannot be explained by any systemic effect of DCA. Rather, it appears that in the immature rat, DCA treatment results in activation of brain PDH, increased metabolism of brain pyruvate and lactate, and a resulting increase in brain glycolytic rate.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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