Relationship between age and risk taking among managers.

Administered a short version of N. Kogan and M. Wallach's (see pa, vol. 39:6826) choice-dilemma test to 1,484 managers from over 200 companies. Results show a significant negative relationship between age and both risk taking and the value placed upon risk. The relationships were small in size when individual scores were correlated with age, but increased markedly when mean scores were used. Furthermore, the relationships were relatively stable across items and across companies. Developmental and sociocultural mechanisms that might underlie these findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Silicone- and ethylene-vinyl-acetate-coated laser-drawn silica fibres with tensile strengths >3.5 GN/m2 (500 kp.s.i.) in >3 km lengths

Tensile strength measurements have been made on fused silica fibres coated with a silicone resin or an ethylene-vinyl-acetate (e.v.a.) hot-melt adhesive. The average strength measured in 20 m guage lengths was 4.7 GN/m2 (671 kp.s.i.) for 3 km of silicone-coated fibre and 5.2 GN/m2 (743 kp.s.i.) for 3.6 km of the e.v.a.-coated fibres. Although control of many drawing and coating process parameters is required to achieve these strengths, the results suggest that under similar conditions other coating systems may perform equally well.     

Application of laser fusion to the radiolytic production of hydrogen

A preliminary conceptual design of a plant to produce hydrogen by laser-fusion-induced steam radiolysis has been developed. It consists of a suppressed ablation lithium wetted wall cavity surrounded by pure and borated steam regions in which fusion neutrons deposit a substantial fraction of their energy, causing nuclear heating in the steam and structural materials, as well as radiolysis of water molecules. Coupled photon-neutron transport calculations have been performed to determine the energy deposited in the different regions of the reactor, and subsequently the amount of hydrogen and nuclear heating generated for various sets of reactor dimensions. The results of these calculations have been used to perform an economic analysis based on scaled costs of the corresponding component systems of proposed laser fusion power plants and hydrogen-generating or handling facilities. The production costs of hydrogen and electric power produced by the laser fusion hydrogen/electric plant considered have been estimated. It has been found that within the uncertainty of these estimates, and for laser fusion output parameters reasonably expected for a first-generation reactor, the computed hydrogen and electric power production costs are not competitive with current prices of natural gas and oil, and electrical power generated by alternate means. However, with an extension of the expected range of output values to significantly higher pellet gains, hydrogen production could become economically attractive.     

The radiation crosslinking of poly(vinyl chloride) with trimethylolpropanetrimethacrylate. III. Effect of diundecyl phthalate: Chemical kinetics of a three-component system

The radiation chemistry of poly(vinyl chloride) (PVC) blended with trimethylolpropanetrimethacrylate (TMPTMA) and diundecyl phthalate (DUP) has been examined. This three-component mixture contains a base resin (PVC), a crosslinking sensitizer (TMPTMA), and a physical modifier (DUP). These are the basic components in any radiation-curable coating. The kinetics and mechanism of the crosslinking reactions were studied with reference to the dependence on radiation dose and blend composition. The polyfunctional TMPTMA underwent polymerization incorporating the PVC into a 3-dimensional network. DUP remained chemically inert during the irradiation, not being bound to the network. However, DUP by plasticizing the macromolecules and diluting the monomer, changed the kinetics extensively. DUP enhanced TMPTMA homopolymerization, TMPTMA grafting, and PVC crosslinking reaction rates. The effect on the competition between polymerization, grafting, and degradation reactions was examined in terms of enhanced mobility of the reacting species. The influence of these kinetic considerations in selecting a blend composition for a coating application was discussed.     

On the validity of the Vroom-Yetton model.

Reports an empirical evaluation of the validity of the Vroom-Yetton contingency model of leadership behavior (V. H. Vroom and P. W. Yetton, 1973). Naive to the model, 96 managers from a variety of organizations described 181 actual problem-solving or decision-making situations and their behavior in these situations. The model was then employed to predict ratings of the technical quality, subordinate acceptance, and the overall effectiveness of the final solutions chosen or decisions made. Substantial support for the model and its various components was obtained. Its concurrent validity was greater than that of a noncontingent model proposed by other theorists. The validity of the Vroom-Yetton model is due, in large measure, to relationships between agreement with the model and subordinate acceptance of or commitment to decisions. Relationships with decision quality were smaller. Reasons for this difference and possible deficiencies of the model are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Division of labor and performance under cooperative and competitive conditions.

The degree to which group members had similar preference orderings among task functions and the degree to which they could observe each other's performance were hypothesized to interact with competitive and cooperative group relationships in determining the extent to which they divided their labor and the level of the group performance. 15 cooperative and 15 competitive dyadic groups worked on jigsaw puzzles under 3 different task conditions: Low Observability-Low Similarity of Preference, High Observability-Low Similarity of Preference, and High Observability-High Similarity of Preference. The division of labor and performance scores of cooperative and competitive groups were similar when the Observability of other's performance and the Similarity of Preference among task functions was low. The relative superiority in division of labor and performance of cooperative groups as compared with competitive groups increased as both Observability and Similarity of Preference increased. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some personality determinants of the effects of participation.

"The primary purpose of this study was to determine the effects of participation in decision-making on persons with different personality characteristics. It was hypothesized that equalitarians and individuals with strong independence needs would be more positively affected by the opportunity to participate in making decisions than authoritarians and persons with weaker independence needs." The results, based on data derived in an actual industrial setting, confirmed the hypothesis. The theoretical implications of the findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Time-gated fluorescence lifetime imaging and microvolume spectroscopy using two-photon excitation

A scanning microscope utilizing two-photon excitation in combination with fluorescence lifetime contrast is presented. The microscope makes use of a tunable femtosecond titanium:sapphire laser enabling the two-photon excitation of a broad range of fluorescent molecules, including UV probes. Importantly, the penetration depth of the two-photon exciting (infra)red light is substantially greater than for the corresponding single-photon wavelength while photobleaching is significantly reduced. The time structure of the Ti:Sa laser can be employed in a straightforward way for the realization of fluorescence lifetime imaging. The fluorescence lifetime is sensitive to the local environment of the fluorescent molecule. This behaviour can be used for example to quantify concentrations of ions, such as pH and Ca²⁺, or pO₂ and pCO₂. In the set-up presented here the fluorescence lifetime imaging is accomplished by time-gated single photon counting. The performance and optical properties of the microscope are investigated by a number of test measurements on fluorescent test beads. Point-spread functions calculated from measurements on 230-nm beads using an iterative restoration procedure compare well with theoretical expectations. Lifetime imaging experiments on a test target containing two different types of test bead in a fluorescent buffer all with different lifetimes (2.15 ns, 2.56 ns and 3.34 ns) show excellent quantitative agreement with reference values obtained from time correlated single photon counting measurements. Moreover, the standard deviation in the results can be wholly ascribed to the photon statistics. Measurements of acridine orange stained biofilms are presented as an example of the potential of two-photon excitation combined with fluorescence lifetime contrast. Fluorescence lifetime and intensity images were recorded over the whole sample depth of 100 μm. Fluorescence intensity imaging is seriously hampered by the rapid decrease of the fluorescence signal as a function of the depth into the sample. Fluorescence lifetime imaging on the other hand is not affected by the decrease of the fluorescence intensity.