The Power of Statistical Tests for Moderators in Meta-Analysis.

Calculation of the statistical power of statistical tests is important in planning and interpreting the results of research studies, including meta-analyses. It is particularly important in moderator analyses in meta-analysis, which are often used as sensitivity analyses to rule out moderator effects but also may have low statistical power. This article describes how to compute statistical power of both fixed- and mixed-effects moderator tests in meta-analysis that are analogous to the analysis of variance and multiple regression analysis for effect sizes. It also shows how to compute power of tests for goodness of fit associated with these models. Examples from a published meta-analysis demonstrate that power of moderator tests and goodness-of-fit tests is not always high. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experimental Testing and Computer Simulations of Ductile Fracture in Tool Steels

Ductility was determined in experimental four‐point bending tests of smooth specimens of tool steel. The tool steels had different contents of carbides and carbide sizes and with a hardness of approximately 60HRc. Two of the materials tested were produced powder metallurgically, one was spray formed and one was conventionally uphill ingot cast. Carbide size distribution analysis was performed on planar polished sections of each material. Correlation between carbide microstructure and ductility performance was obtained. The fracture mechanisms were investigated with fractography. A 3D FE‐model was used to simulate the four‐point bending tests and thereby analyse the matrix flow curve. Also the strain at failure was analysed for each material when simulations were performed based on experimental data. SEM‐images of the materials carbide microstructure were used to create 2D FE‐models. The models simulated crack initiation and propagation by removing elements in the steel matrix as the plastic strain reached a critical level. With three variants, simulations of crack initiation and propagation at carbides were investigated. That was carbides with no cohesion to matrix, carbides fixed to the matrix and carbides with internal cracks. Comparison of strains at failure for the 2D and the 3D FE‐models showed good correlation.     

Cathodic reduction of different metal salt solutions Part I: synthesis of metal hydroxides by electrogeneration of base

The yield of metal hydroxides obtained by electrolysis of chloride baths is greater than the yield obtained from nitrate baths showing that the hydrogen evolution reaction (HER) contributes as much to electrogeneration of base as the nitrate reduction reaction. This observation has implications for the fabrication of nickel hydroxide positive electrodes for alkaline secondary cells, and widens the scope of electrosynthesis to include chloride, sulphate and other anion containing -nickel hydroxides and other layered hydroxides. Electrosynthesis of Mg(OH)2 has been investigated as a model synthesis.     

具有合格的乙醛产生速度的高特性黏度熔融相聚酯聚合物

正生产固体聚酯聚合物粒子的方法包括:a)在缩聚催化剂组成物存在下,缩聚熔融的聚酯聚合物组成物,催化剂组成物含有锑类化合物;b)连续熔融聚酯聚合物组成物的缩聚反应达到0.68dL/g或更高;c)达到0.68dL/g或更高后,将催化剂稳定剂或去活性剂加入熔融的聚合物;d)在达到0.68dL/g或更高后,固化熔融物成固体聚酯聚合物粒子,其不含有机乙醛净化剂。     

Hot-electron bolometer terahertz mixers for the Herschel Space Observatory

We report on low noise terahertz mixers (1.4-1.9 THz) developed for the heterodyne spectrometer onboard the Herschel Space Observatory. The mixers employ double slot antenna integrated superconducting hot-electron bolometers (HEBs) made of thin NbN films. The mixer performance was characterized in terms of detection sensitivity across the entire rf band by using a Fourier transform spectrometer (from 0.5 to 2.5 THz, with 30 GHz resolution) and also by measuring the mixer noise temperature at a limited number of discrete frequencies. The lowest mixer noise temperature recorded was 750 K [double sideband (DSB)] at 1.6 THz and 950 K DSB at 1.9 THz local oscillator (LO) frequencies. Averaged across the intermediate frequency band of 2.4-4.8 GHz, the mixer noise temperature was 1100 K DSB at 1.6 THz and 1450 K DSB at 1.9 THz LO frequencies. The HEB heterodyne receiver stability has been analyzed and compared to the HEB stability in the direct detection mode. The optimal local oscillator power was determined and found to be in a 200-500 nW range.     

DNA‐Targeted Inhibition of MGMT

The cationic porphyrin 5,10,15,20‐tetrakis (diisopropyl‐guanidine)‐21H,23H‐porphine (DIGPor) selectively binds to DNA containing O⁶‐methylguanine (O⁶‐MeG) and inhibits the DNA repair enzyme O⁶‐methylguanine‐DNA methyltransferase (MGMT). The O⁶‐MeG selectivity and MGMT inhibitory activity of DIGPor were improved by incorporating Zn^II into the porphyrin. The resulting metal complex (Zn‐DIGPor) potentiated the activity of the DNA‐alkylating drug temozolomide in an MGMT‐expressing cell line. To the best of our knowledge, this is the first example of DNA‐targeted MGMT inhibition.     

Adrenalectomy reduces peripheral neural responses to gustatory stimuli in the rat.

The adrenalectomized rat, because of excessive body sodium loss, has been an important animal model for studying the physiological mechanisms underlying salt ingestion. To investigate the mediation by peripheral taste responsivity of changes in salt intake, multiunit responses of the chorda tympani nerve to various concentrations of NaCl, KCl, and LiCl, hydrochloric acid, and quinine hydrochloride were recorded from 18 adrenalectomized or intact male Sprague-Dawley rats. To control for a generalized decrease in sensory sensitivity, recordings from this auriculotemporal nerve to tactile stimulation of the pinna were also performed. There were no group differences in amplitude of the integrated neural responses to tactile stimulation. The largest decrease in gustatory responsivity occurred for suprathreshold concentrations of NaCl and LiCl. Data are discussed with reference to possible mechanisms underlying this neural alteration and the role that reductions in salt taste responsivity play in mediating increases in salt intake. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)