A review and meta-analysis of the antecedents, correlates, and consequences of organizational commitment.

In this article, we summarize previous empirical studies that examined antecedents, correlates, and/or consequences of organizational commitment using meta-analysis. In total, 48 meta-analyses were conducted, including 26 variables classified as antecedents, 8 as consequences, and 14 as correlates. Statistical artifacts were found to account for the variance between studies in only one meta-analysis that used attendance. Type of organizational commitment (attitudinal vs. calculative) was proposed as a moderator variable and was found to account for significant between-study variance in 9 of 18 comparisons. Theoretical and methodological issues pertaining to the measurement of various forms of organizational commitment, its interrelations with other forms of attachments, and its role in causal models of behavior in organizations are reviewed. Directions for future research are highlighted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modeling and simulation of paraplegic ambulation in a reciprocating gait orthosis

We developed a three dimensional, four segment, eight-degree-of-freedom model for the analysis of paraplegic ambulation in a reciprocating gait orthosis (RGO). Model development was guided by experimental analysis of a spinal cord injured individual walking in an RGO with the additional assistance of arm crutches. Body forces and torques required to produce a dynamic simulation of the RGO gait swing phase were found by solving an optimal control problem to track the recorded kinematics and ground reaction forces. We found that high upper body forces are required, not only during swing but probably also during double support to compensate for the deceleration of the body during swing, which is due to the pelvic thrust necessary to swing the leg forward. Other stimulations showed that upper body forces and body deceleration during swing can be reduced substantially by producing a ballistic swing. Functional neuromuscular stimulation of the hip musculature during double support would then be required, however, to establish the initial conditions needed in a ballistic swing.     

Impaired regulation of hepatic fructose-1,6-biphosphatase in the New Zealand Obese mouse: an acquired defect

Increased hepatic glucose production, a feature of (non-insulin-dependent diabetes mellitus [NIDDM]), is present at an early age in the New Zealand Obese (NZO) mouse and is associated with impaired suppression of the gluconeogenic enzyme, fructose-1,6-bisphosphatase (FBPase). The aim of this study was to further characterize the abnormality in the regulation of hepatic FBPase in NZO mice versus New Zealand Chocolate (NZC) control mice. At 20 weeks of age, NZO mice have elevated FBPase activity (65.3 +/- 7.9 v 46.7 +/- 5.0 micromol/min/mg protein, P =.07) and protein levels (31.7 +/- 3.1 v 22.5 +/- 2.8 arbitrary units, P < .05), but not mRNA levels (0.18 +/- 0.03 v 0.16 +/- 0.03 arbitrary units). Elevated FBPase activity and protein levels in NZO mice were also shown at 4 to 6 weeks of age, but not in 1-day-old mice, suggesting that the increase occurs between birth and weaning. The Km of the enzyme was the same in NZO and NZC mice (3.7 +/- 0.5 v 5.0 +/- 0.9 micromol/L, NZO v NZC). The regulation of FBPase by the competitive inhibitor, fructose-2,6-bisphosphate ([Fru(2,6)Pz] 5 micromol/L) measured over a range of substrate concentrations (2.5 to 80 micromol/L) was similar between NZO and control mice (Km in the presence of Fru(2,6)Pz, 10.8 +/- v 1.9 v 13.2 +/- 3.3 micromol/L, NZO v NZC). It is concluded that increased FBPase activity in the NZO mouse is due to elevated protein levels, and that this appears to be due to a failure of the normal decrease that occurs following birth in control animals.     

Magnetic Properties of (Ga,Fe)N

Wurtzite (Ga,Fe)N bulk crystals were, for the first time, successfully grown by AMMONO and chemical transport methods. The magnetization measurements of (Ga,Fe)N crystals revealed the coexistence of paramagnetic and ferromagnetic contributions. The paramagnetic component was shown to be growth condition dependent. The Brillouin-type behavior was observed in the samples obtained by both methods. Some (Ga,Fe)N samples (especially those codoped with Si) grown by the chemical transport method show a Van Vleck–type paramagnetic behavior.     

The influence of heat treatment and finishing on the mechanical and dielectric properties of glass fabric-epoxy resin laminar composites

The aim of this investigation was to define the optimum conditions of obtaining glass fabric-epoxy resin laminar composites with mechanical and dielectric properties that satisfy the quality needed for production of printed circuit boards for microelectronics. Commercial materials: glass woven fabric, different types of silane finish and epoxy resin were the starting materials in obtaining composites. The conditions needed for the thermal removal of the original size from glass fabric were investigated. The optimal heat treatment should be performed at temperatures less than 550 °C, while cooling rates should be as low as possible. In this manner, the fabric has less than 0.1% of residual size, and the mechanical properties remain satisfactory. Different types of adhesion promoters based on silanes were applied on heat-treated glass fabric as finishes. The quality of the composite material made of thermally and chemically treated glass fabric and epoxy resin was controled by measuring the tensile and dielectric strength of the composite. Depending on which properties of composite are of primary concern, mechanical or dielectric, a finish with an amino functional group and lower heat-treatment temperature or epoxy-modified coatings and higher heat-treatment temperature should be used for obtaining glass-fabric epoxy resin laminar composites.     

Hydrogen evolution on platinum in the presence of lead,cadmium and thallium adatoms

Hydrogen evolution on rotating platinum electrode has been measured in the presence of Pb, Tl and Cd adatoms. At low coverages of these adatoms (θ_M < 0.5) the mechanism of H₂ evolution is the same as that for Pt, giving rise to the Tafel slope of 30 mV with recombination of H adatoms as a rate controlling step. However, H₂ evolution decreases with θ_M to the fourth power, due to a simple blocking of Pt surface and a decrease of number of pairs of Pt atoms necessary for a recombination reaction. At higher coverages of foreign metal adatoms (θ_M ? 0.5), when the activation energy for the recombination of H adatoms becomes too high, the ion-plus atom reaction begins to control the rate of reaction. The Tafel slope acquires a value of 120 mV. Now, a decrease of H₂ evolution has been found proportional to the coverage of metal adatoms. A quantitative analysis based on above model agrees very well with the experiment. Some information on underpotential deposition of above metal on Pt has also been obtained.     

On propelling a rod to a maximum vertical or horizontal distance

In order to clarify the problems associated with the application of optimal control theory to the control of animal and human movement, the much simpler but related problems of causing a rod to execute a maximal vertical or horizontal jump are solved via elementary methods. The solutions, which are given in feedback form, are nearly identical even though the performance criteria are quite different. For certain initial conditions an optimal trajectory exists along which the gradient of the optimal performance with respect to the state is discontinuous. A technique to find these trajectories is given. The extension of these results to more realistic models of humans, animals, or walking machines is described.     

Propelling a torque controlled baton to a maximum height

Recent applications of optimal control theory to the analysis of human and animal locomotion have resulted in optimal control problems that are too complex for analytic solution. Furthermore, these problems involve unusual constraints and dynamics. In order to provide a clearer understanding of the problems involved, the much simpler but related problem of causing a baton to "jump" maximally has been completely solved via elementary methods. The solution is given in feedback form. The state space divides into several regions according to the form of the optimal control. There exist regions where many controls are globally optimal, regions where a locally optimal control and a globally optimal control both exist, and regions where a unique globally optimal control exists. Finally, some relations between these results and experimental observations in both human and animal jumping are discussed.     

Chemical and physical properties of processed newspaper compared to wheat straw and wood shavings as animal bedding

Because of continuing concerns about the safety and the suitability of recycled newspaper as an animal bedding material, municipal curbside-collected newspaper was processed into chopped and pelleted forms for comparison studies with wheat straw and kiln-dried pinewood shavings. Measurements included nutrient, heavy metal, dioxin and furan content, particle size distribution, density, combustion potential, and water-holding capacity. Recycled newspaper, straw, and wood shavings tested below or equivalent to National Research Council dietary tolerance levels and US Environmental Protection Agency toxic equivalent levels. Small particle size distribution was shavings > straw > all forms of newspaper. The density of pelleted newspaper was 50-fold greater than that of chopped newspaper and straw and 15-fold greater than shavings. In simulated flash burns, chopped newspaper, straw, and shavings ignited, and flames spread rapidly in newspaper and shavings and lasted the longest in shavings. Pelleted newspaper did not ignite. Chopped and pelleted forms of newspaper and wood shavings had higher water holding capacities (>400%) than did straw (200%). Animal industries can, in confidence, utilize recycled newspaper as an animal bedding material, providing that sources of low toxicity are identified, and suitable processed forms are produced.