Browsing by Subject "Analysis of variance"

Now showing 1 - 3 of 3
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    Impact of glucocorticoid receptor density on ligand-independent dimerization, cooperative ligand-binding and basal priming of transactivation: a cell culture model
    (Public Library of Science, 2013) Robertson, Steven; Rohwer, Johann M; Hapgood, Janet P; Louw, Ann
    Glucocorticoid receptor (GR) levels vary between tissues and individuals and are altered by physiological and pharmacological effectors. However, the effects and implications of differences in GR concentration have not been fully elucidated. Using three statistically different GR concentrations in transiently transfected COS-1 cells, we demonstrate, using co-immunoprecipitation (CoIP) and fluorescent resonance energy transfer (FRET), that high levels of wild type GR (wtGR), but not of dimerization deficient GR (GRdim), display ligand-independent dimerization. Whole-cell saturation ligand-binding experiments furthermore establish that positive cooperative ligand-binding, with a concomitant increased ligand-binding affinity, is facilitated by ligand-independent dimerization at high concentrations of wtGR, but not GRdim. The down-stream consequences of ligand-independent dimerization at high concentrations of wtGR, but not GRdim, are shown to include basal priming of the system as witnessed by ligand-independent transactivation of both a GRE-containing promoter-reporter and the endogenous glucocorticoid (GC)-responsive gene, GILZ, as well as ligand-independent loading of GR onto the GILZ promoter. Pursuant to the basal priming of the system, addition of ligand results in a significantly greater modulation of transactivation potency than would be expected solely from the increase in ligand-binding affinity. Thus ligand-independent dimerization of the GR at high concentrations primes the system, through ligand-independent DNA loading and transactivation, which together with positive cooperative ligand-binding increases the potency of GR agonists and shifts the bio-character of partial GR agonists. Clearly GR-levels are a major factor in determining the sensitivity to GCs and a critical factor regulating transcriptional programs.
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    Own-Race Faces Capture Attention Faster than Other-Race Faces: Evidence from Response Time and the N2pc
    (Public Library of Science, 2015) Zhou, Guomei; Cheng, Zhijie; Yue, Zhenzhu; Tredoux, Colin; He, Jibo; Wang, Ling
    Studies have shown that people are better at recognizing human faces from their own-race than from other-races, an effect often termed the Own-Race Advantage. The current study investigates whether there is an Own-Race Advantage in attention and its neural correlates. Participants were asked to search for a human face among animal faces. Experiment 1 showed a classic Own-Race Advantage in response time both for Chinese and Black South African participants. Using event-related potentials (ERPs), Experiment 2 showed a similar Own-Race Advantage in response time for both upright faces and inverted faces. Moreover, the latency of N2pc for own-race faces was earlier than that for other-race faces. These results suggested that own-race faces capture attention more efficiently than other-race faces.
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    Quality assurance in high schools through regression analysis
    (1997) Watermeyer, John Westerton; Gilmour, James David; Dunne, Tim T
    School Effectiveness is a relatively new and poorly defined domain for which a structure is proposed, to facilitate future discussion. Three fields within School Effectiveness are identified, namely School Effectiveness Research (SER), School Improvement (SI) and Quality Assurance (QA). Three divisions are identified within each field on the basis of various criteria. SER has methodological generations, Sl is classified by decade, and three themes of QA are described, including performance indicators (Pis). A definition of effectiveness in terms of regression lines is described and the concept of added value or adjusted achievement developed. This study is concerned with the development of Pis for use within a single school to monitor and promote improvement. The context of the study (a model C senior high school in a predominantly white southern suburb of Cape Town) and the data collected is described before a review is made of some of the analyses which could be used to monitor effectiveness. A technique whereby pupil achievement is adjusted (for prior achievement and other background variables) and the residuals (or adjusted achievement) derived from the regressions investigated with one-way A NOVAs is described and tested using various models and subjects. With respect to groups, it is proposed that statistical significance of differences between mean residuals could be used as a PI. With respect to individual pupils, educators could set their own criterion for investigating cases where adjusted achievement is very large or very small. Statistical significance requires interpretation, however, and the role of professional judgement in modelling and monitoring adjusted achievement is discussed. The view that techniques such as regression analysis can only indicate when professional investigation and intervention might be necessary is stressed. It would seem unwise to rank teachers or subjects on the basis of adjusted achievement.