Stress reactions to computer‐interactive tasks as a function of task structure and individual differences

The resurgence of interest in occupational stress has resulted in an emphasis on identifying work conditions that are potentially causal in generating stress reactions and psychological disorders among workers. Although a considerable knowledge base related to this topic has evolved, relatively little is known regarding the impact of computer technology on incidence of job stress. This issue is especially important for older workers, given the increased use of computers in most occupations, the aging of the workforce, and the changes in cognitive and physiological capacities that occur with increased age. The study reported in this article was concerned with developing a methodology to evaluate stress for computer‐interactive tasks as a function of the mental workload of the task and the age of the individual. Sixty‐five women ranging in age from 25 to 70 years performed three computer‐interactive tasks that varied as a function of information processing complexity and pacing requirements. The methodology encompassed physiological, subjective, and performance measures. Results indicated differences in sensitivity among the measures as a function of task and age. The data also indicated age differences in stress reactions and performance. The findings are discussed in terms of the suitability of computer tasks for older people.     

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Nachweis von Mutterkorn und Taumellolch im Mehl im gew?hnlichen Licht- und im Polarisationsmikroskop

Zusammenfassung Für den bislang wenig befriedigenden mikroskopischen Nachweis der beiden giftigen Verunreinigungen von Getreidemehlen, Mutterkorn, Sklerotien vonClaviceps purpurea Tul. und Taumellolch (Lolium temulentum L.) werden neue, charakteristische Reaktionen bzw. das Verhalten bei Untersuchung im polarisierten Licht vorgeschlagen.     

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Independent effects of estradiol on water and food intake.

Conducted 6 experiments to examine the effects of estradiol on ingestive behaviors of guinea pigs. Estradiol treatment was found to reduce water intake independently of its actions on food intake and body weight. In the 1st experiment, minimum intake and body weight of 17 intact female guinea pigs coincided with rupture of the vaginal membrane, the estimated time of ovulation. In Exp II, injections of 3 μg of estradiol benzoate (EB)/day to 7 ovariectomized females significantly depressed food intake, water intake, and body weight, compared with 7 Ss that received oil injections. Reducing food rations to 30% below ad lib levels in Exp III by itself had no significant effect on drinking in ovariectomized Ss. In Exp IV, therefore, ovariectomized females were first placed on a food ration 30% below ad lib levels and then injected daily with either 3 μg of EB or oil. Compared with oil injections, these EB injections significantly reduced water intake, while food intake did not decline significantly. Findings indicate that estradiol operates through different mechanisms to affect water intake and food intake. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Der Nachweis von Alginaten in Trockenmischungen und Zubereitungen mittels des Polarisationsmikroskops

Zusammenfassung Auf Grund der Tatsache, daB die Alginate ionotrope biologische Gele darstellen und als solche besondere kolloidchemische Eigenschaften besitzen bzw. besonderes Verhalten zeigen, werden Methoden angegeben zum Nachweis von Alginaten, trocken rein oder in Mischungen mit anderen trockenen Substanzen und in gelöstem Zustand. Im trockenen wie im gelösten Zustand wird die Fähigkeit der Alginate zum Ionenaustausch an ihren Carboxylgruppen (Ca⁺⁺, Pb⁺⁺, UO₂ ⁺⁺ gegen Na⁺ und andere) und damit zur Anderung der Doppelbrechung, Hydratation und Vernetzung der Makromoleküle, Bildung von runden Schichten bzw. Schalen bei Diffusion der austauschenden Ionen von einem Punkt aus in verschiedonen Richtungen (ionotrope Sphïtenscheibchen) benutzt und polarisationsmikroskopisch dargestellt.     

Self-accommodated and pre-strained martensitic microstructure in single-crystalline,metamagnetic Ni–Mn–Sn Heusler alloy

Metamagnetic shape memory alloys are a unique class of materials capable of large magnetic field-induced strain due to reverse martensitic phase transformation. A precondition for large shape change is martensite deformation, which heavily depends on microstructure. Elucidation of microstructure is therefore indispensable for strain control and deformation mechanics in such systems. The current paper reports on a self-accommodated martensitic microstructure in metamagnetic Ni₅₀Mn_37.5Sn_12.5 single crystal. The microstructure here is hierarchically organised at three distinct levels. On a large scale, martensite plate colonies, distinguished by intercolony boundaries, group individual martensitic plates. Plates are separated by interplate boundaries and deviate by 2.2° from an ideal twin relation. On the lower scale, plates are composed of subplate twins. Conjugation boundaries separating two pairs of twins arise in relation to a subplate microstructure. Modulation boundaries separating two variants with perpendicular modulation directions and with parallel c-axes also appear. Mechanical training frees larger plates from fine subplate microtwins bringing macro-lamellae into twin relation, what then permits further detwinning until a single variant state.     

Molecular Heteroconjugation Equilibria in (n-Butylamine + Acetic Acid) Systems in Binary (Dimethyl Sulfoxide + 1,4-Dioxane) Solvent Mixtures

The acidity constants of molecular acid, K _a (HA), cationic acid, K _a (BH⁺), as well as the equilibrium constants of anionic homoconjugation, , cationic homoconjugation, , and molecular heteroconjugation, K_AHB, have been determined in (n-butylamine + acetic acid) systems without proton transfer in binary [dimethyl sulfoxide (DMSO) + 1,4-dioxane (D)] solvent mixtures. The constants were determined by using the potentiometric titration method at a fixed ionic strength. It is concluded that the molecular heteroconjugation constants in the mixed solvent systems studied are linearly related to the 1,4-dioxane content. Furthermore, in the (acid + base) systems without proton transfer, the direction of titration (direct B + HA or reverse HA + B) has been found to affect the precision of determination of reliable values of molecular heteroconjugation constants. Moreover, it has been found that the relative dielectric constants of the solvent mixtures studied change linearly as a function of solvent composition, as well as solvent components do not show interactions of solvent–solvent type.     

Nature of activating effect of two‐step polymerization of propylene

The prepolymerization effect on propylene polymerization in the presence of a TiCl₃‐based catalyst, modified by di‐n‐buthyl ether, was studied. The influence of prepolymerization on the electron spin resonance spectra and morphology of the catalyst, as well as the properties and the morphology of both prepolymer and regular polymerization products, was investigated. The polymer morphology was evaluated through scanning electron microscopy, polymer bulk density, and particle size distribution. Some evidence of the enhancement effect of prepolymerization on the catalyst activity and stereospecificity was obtained. No influence from prepolymerization was observed on molecular weight and its distribution, melting point, and crystallinity of polypropylene. These findings, when discussed in connection with the morphology results of the catalyst and prepolymer, showed that the prepolymerization performed at mild reaction conditions prevents fast and extensive “fragmentation” of the original catalyst agglomerates. The more controlled breakup of the catalyst particles in the course of slowed growth of prepolymer exposes the occluded catalyst fragments with uniform size and prevents their reagglomeration. Resulting from the above, catalyst homogeneity, catalyst activity, and polymer morphology are improved. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 353–359, 1999