Hardened portland cement pastes of low porosity VI. Mechanism of the hydration process

The hydration of low-porosity portland cement pastes may be divided into three stages. The first stage starts with a fast hydration until 10 to 15% of the cement is hydrated (pre-dormant period), which is followed by a very slow hydration, caused by the formation of a coating on the cement grains (dormant period). After 15 to 20% of the cement is hydrated, the coating is ruptured, and a fast reaction starts, which lasts until about 30% of the cement is hydrated. This is the second stage of the reaction. In the third stage, the hydration slows down, due to retardation by the accumulating hydration products. The mechanism of the third stage is treated quantitatively. The diffusion through the very narrow pores between the hydration products is activated diffusion, and the apparent energy of activation of the diffusion is calculated.     

Planning of randomized early detection trials

Consider a randomized clinical trial to evaluate the benefit of screening an asymptomatic population. Suppose that the subjects are randomized into a usual care and a study group. The study group receives one or more periodic early detection examinations aimed at diagnosing disease early, when there are no signs or symptoms. Early detection clinical trials differ from therapeutic trials in that power is affected by: i) the number of exams, ii) the time between exams and iii) the ages at which exams will be given. These design options do not exist in therapeutic trials. Furthermore; long-term follow-up may result in a reduction of power. In general, power increases with number of examinations, and the optimal follow-up time is dependent on the spacing between examinations. Clinical trials in which the usual care group receives benefit are also discussed. Two designs are discussed, for example the 'up-front design' in which all subjects receive an initial exam and then are randomized to the usual care and study groups and the 'close-out design' in which the usual care group receives an exam which is timed to be given at the same time as the last exam in the study group. Both families of designs significantly reduce the power. Power calculations are made for two clinical trials, which actually used these two designs.     

Relations among scores on Edwards Personal Preference Schedule, California Psychological Inventory, and Strong Vocational Interest Blank for an industrial sample.

The significant intercorrelations among scores on the EPPS, the CPI, and the SVIB are reported for a group of 102 salaried employees of the 3M Company. Comparison of the CPI and EPPS scales generally shows correlations in the expected directions, and correlations between occupational interests and personality variables make "good clinical sense." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Birth order and family size of homosexual men and women.

Systematically compared the birth order and family size of 150 male and 99 female homosexuals with those of 108 male and 97 female heterosexuals. Results show that neither birth order nor family size represented distinct or meaningful contrasts between male or female homosexuals or heterosexuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thermodynamic and nonstoichiometric behavior of promising Hi-Tc cuprate systems via electromotive force measurements: A short review

Electromotive force (EMF) measurements of oxygen fugacities as a function of stoichiometry have been made on the YBa₂Cu₃O _x , GdBa₂Cu₃O _x , NdBa₂Cu₃O _x , and bismuth cuprate systems in the temperature range ∼400 °C to 750 °C by means of an oxygen titration technique with an yttriastabilized zirconia electrolyte. The shapes of the 400 °C isotherms as a function of oxygen stoichiometry for the Gd and Nd cuprate systems suggest the presence of miscibility gaps at values of x that are higher than those in the YBa₂Cu₃O _x system. For a given oxygen stoichiometry, oxygen partial pressures above GdBa₂Cu₃O_x and NdBa₂Cu₃O _x the higher (above x=6.5) than that for the promising YBa₂-Cu₃O_x system. This article is based on a presentation made at “The Milton Blander Symposium on Thermodynamic Predictions and Applications” at the TMS Annual Meeting in San Diego, California, on March 1–2, 1999, under the auspices of the TMS Extraction and Processing Division and the ASM Thermodynamics and Phase Equilibrium Committee.     

Operationalizing Gestalt therapy's processes of experiential organization.

Developed a coding system to operationalize the Gestalt therapy formulation of experiential organization and used the scale to test the assumption that each member of an interacting couple is influenced by concurrent organization of experience processes of the other. 20 couples (at least 1 member was an undergraduate student) who had lived together for at least 6 mo were rated. Findings support the reliability of the procedure, but data do not reflect adequate levels of usage along the full range of the scale. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)