Work involvement: A comparison of dual wage earner and single wage earner families.

Studied job involvement and organizational identification among 286 municipal employees (mean age 39.4 yrs) in a large Southern city. Both job involvement and organizational identification were lower among males whose spouses were employed than among those whose spouses were not employed. For Ss whose spouses were employed, job involvement and organizational identification were higher for Ss with children than it was for childless Ss. Sex, education, and organizational tenure were controlled using multivariate statistical techniques. Results support a financial-need hypothesis that predicts that work involvement will be higher in cases in which financial requirements are greater. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spontaneous output of acetylcholine from rat diaphragm preparations declines after treatment with botulinum toxin

A gas chromatographic spectrometric assay was used to measure tissue and released acetylcholine and choline in diaphragm preparations of rats previously injected with botulinum toxin type A. Botulinum intoxication was found not to alter the acetylcholine content of rat diaphragms in vivo or in fully paralyzed muscles in vitro. This result provides direct support for the hypothesis that botulinum toxin blocks transmitter release without affecting acetylcholine synthesis. However, in diaphragm preparations in vitro, this toxin was found to inhibit not only the evoked release of acetylcholine but also the spontaneous "leakage" of acetylcholine that is measured at rest. Additional experiments were performed to characterize this action of the toxin. The magnitude of the decline in resting acetylcholine output appears to be too large to be accounted for solely by the known effect of botulinum toxin to reduce the frequency of miniature endplate potentials. The mechanism of this action of botulinum toxin remains an enigma.     

Ion-pairs in proteins

A "working definition" for an ion-pair has been derived based upon analysis of the distance distributions for like- and oppositely charged groups in 38 proteins. Ion-pairs defined according to this criterion (less than or equal to 4 A between charged groups) have been analysed in respect of: (1) the frequencies of different pair types; (2) the residue separations and secondary structural locations of the residues involved; (3) the flexibility of the side-chains involved; (4) their conformation; (5) their environment (accessibility to solvent and proximity to active site or ligand binding regions); and (6) their conservation in related proteins. The results obtained indicate that on average one-third of the charged residues in a protein are involved in ion-pairs and 76% of these are concerned with stabilizing the tertiary (rather than the secondary) structure. Only 17% of ion-pairs are buried, and conservation of the interactions is generally low unless the residues involved have more specific functions to perform. In the light of the results obtained, the role of ion pairs in globular proteins is discussed.     

Changes in the chemical reactivity of metals exposed to an inert gas glow discharge

From time to time the literature mentions curious effects on the chemical reactivity of metals due to inert gas ion bombardment: reactivity in corrosive environments is variously said to be inhibited or enhanced. Although there is no obvious explanation for such effects, some possible mechanisms have been suggested. We have carried out a few simple experiments designed to demonstrate that reactivity effects really do exist and to test such mechanisms as have been proposed. The results are qualitative because a glow discharge was used to implant the rare gas ions.Evaporated films of aluminium and nickel become amorphous after bombardment with xenon ions and the films resisted gaseous and liquid corrosion. On the other hand, aluminium foil bombarded with xenon ions in a Penning pump arrangement was attacked more heavily than unbombarded aluminium. We attribute passivation to the known lack of reactivity of amorphous metals. Glassy materials appear to lack the normal routes of attack between their subsurface regions and the attacking medium. On the other hand, when a metal surface is heavily ion bombarded the surface is probably damaged to such an extent that the attacking medium gains physical access to the interior and corrosion proceeds rapidly.     

A hybrid finite difference/helmholtz integral scheme for ultrasonic scattering

Two techniques for analyzing the scattering of elastic waves by flaws are combined in a hybrid model. One is a finite difference scheme for handling the details of the interaction with the flaw, the other is a Helmholtz integral scheme for extending the results into the far field. Results are given for the diffraction coefficients for a semi-infinite thin crack, and for a 270° corner.     

Shells of revolution with local deviations

A finite element model that is suitable for the analysis of shells of revolution with arbitrary local deviations is presented. The model employs three types of shell elements: rotational, general and transitional. The rotational shell elements, which are most efficient, are used in the region where the shell is axisymmetric. The general shell elements, which can simulate almost any shell geometry, are used in the local region of the deviation. The transitional shell elements connect these two distinctively different types of elements and make it possible to combine them in a single analysis. The form of the global stiffness matrix is somewhat unique in the new model. Non-zero terms are not confined to a narrow band along the diagonal, but occur throughout the matrix. This is due to the following: (1) two different types of nodes, ring nodes and point nodes, are combined in a single analysis; and (2) a locally non-axisymmetric geometry creates a coupling of the Fourier harmonic coefficients of the rotational elements. Yet, the matrix still contains many scattered zero terms that should be considered for numerical efficiency. In this paper an efficient solution procedure that is effective for this situation is developed. The steps include the use of a substructuring technique and separate partial harmonic analysis. A numerical example is presented and compared with existing solutions to demonstrate the capabilities and the efficiency of the new model.     

Utilising psychophysical techniques to investigate the effects of age,typeface design,size and display polarity on glance legibility

Psychophysical research on text legibility has historically investigated factors such as size, colour and contrast, but there has been relatively little direct empirical evaluation of typographic design itself, particularly in the emerging context of glance reading. In the present study, participants performed a lexical decision task controlled by an adaptive staircase method. Two typefaces, a ‘humanist’ and ‘square grotesque’ style, were tested. Study I examined positive and negative polarities, while Study II examined two text sizes. Stimulus duration thresholds were sensitive to differences between typefaces, polarities and sizes. Typeface also interacted significantly with age, particularly for conditions with higher legibility thresholds. These results are consistent with previous research assessing the impact of the same typefaces on interface demand in a simulated driving environment. This simplified methodology of assessing legibility differences can be adapted to investigate a wide array of questions relevant to typographic and interface designs.

Practitioner Summary: A method is described for rapidly investigating relative legibility of different typographical features. Results indicate that during glance-like reading induced by the psychophysical technique and under the lighting conditions considered, humanist-style type is significantly more legible than a square grotesque style, and that black-on-white text is significantly more legible than white-on-black.     

Phantom experiments on a PSAPD-based compact gamma camera with submillimeter spatial resolution for small animal SPECT

We demonstrate a position sensitive avalanche photodiode (PSAPD) based compact gamma camera for the application of small animal single photon emission computed tomography (SPECT). The silicon PSAPD with a two-dimensional resistive layer and four readout channels is implemented as a gamma ray detector to record the energy and position of radiation events from a radionuclide source. A 2 mm thick monolithic CsI:Tl scintillator is optically coupled to a PSAPD with a 8mm×8mm active area, providing submillimeter intrinsic spatial resolution, high energy resolution (16% full-width half maximum at 140 keV) and high gain. A mouse heart phantom filled with an aqueous solution of 370 MBq (99m)Tc-pertechnetate (140 keV) was imaged using the PSAPD detector module and a tungsten knife-edge pinhole collimator with a 0.5 mm diameter aperture. The PSAPD detector module was cooled with cold nitrogen gas to suppress dark current shot noise. For each projection image of the mouse heart phantom, a rotated diagonal readout algorithm was used to calculate the position of radiation events and correct for pincushion distortion. The reconstructed image of the mouse heart phantom demonstrated reproducible image quality with submillimeter spatial resolution (0.7 mm), showing the feasibility of using the compact PSAPD-based gamma camera for a small animal SPECT system.     

Effects of treating wheat straw with pH-regulated solutions of alkaline hydrogen peroxide on nutrient digestion by sheep

An experiment using a 4 X 4 Latin square design was to determine effects of treating wheat straw with pH-regulated (pH = 11.5) solutions of hydrogen peroxide on site and extent of nutrient digestion in multiple-fistulated sheep. Regulating reaction pH at 11.5 prevented solubilization of some cell wall hemicelluloses, resulting in improved retention of DM. Diets fed to sheep contained 33 or 70% wheat straw either untreated or treated with alkaline hydrogen peroxide. Sheep fed diets of treated wheat straw digested more DM, NDF, ADF, and cellulose anterior to the duodenum and in the total tract than when fed diets of untreated wheat straw. Apparent CP digestion before the duodenum was highest when sheep were fed the treated 33% wheat straw diet and untreated 70% wheat straw diet. Treatments did not affect apparent nutrient digestibilities in the large intestine. Ruminal pH was lower when sheep were fed the alkaline hydrogen peroxide-treated or diets containing 33% wheat straw. Ruminal ammonia concentrations were highest when sheep were fed the untreated 70% wheat straw diet. Molar proportions of ruminal acetic and propionic acids were unaffected by diet. Alkaline hydrogen peroxide treatment substantially increased susceptibility of structural carbohydrates of wheat straw to microbial degradation in the gastrointestinal tract of sheep.