Perceived similarity and accuracy of peer ratings.

The hypothesis that raters will be more accurate in rating peers perceived to be similar to themselves, suggested by Mumford (1983) and derived from social comparison theory, was examined. Subjects were 681 Israeli entrants to a military training program. Shortly after course inception, subjects were asked to review the performance of squad members and to forecast their final grade. Subjects also judged peers' similarity to self overall (general similarity), in course achievement (foreground similarity), and in military experience (background similarity). Analysis revealed that accuracy was markedly lower in the evaluation of dissimilar others. Although the same patterns of results was observed for all forms of similarity, stronger effects resulted when similarity was measured in terms of general and foreground characteristics. Implications for future theory and research as well as for the practical application of peer assessment are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Instrumentation and vacuum aspects of chemical ionization mass spectrometry

Instrumental modifications involved in conversion of a mass spectrometer for chemical ionization are discussed. These modifications include a gas-tight ion source for operation at 1 torr, a differential pumping system, a gauge for source pressure monitoring, an inlet system for the reagent gas, increase of the electron energy up to 500 eV and modifications in the electron current regulator. Some of the applications and advantages of the technique are briefly reviewed.     

A modular approach for the design of microstrip array antennas

A method for the design of medium gain (15-25 dB) microstrip array antennas is described. A modular approach is utilized in which a given antenna is used as a building block for higher gain antennas. A series ofX-band antennas were built in this way, and the results seem to validate the usefulness of the method.     

Simultaneous retrieval of the complex refractive indices of the core and shell of coated aerosol particles from extinction measurements using simulated annealing

Simultaneously retrieving the complex refractive indices of the core and shell of coated aerosol particles given the measured extinction efficiency as a function of particle dimensions (core diameter and coated diameter) is much more difficult than retrieving the complex refractive index of homogeneous aerosol particles. Not only must the minimization be performed over a four-parameter space, making it less efficient, but in addition the absolute value of the difference between the measured extinction and the calculated extinction does not have an easily distinguished global minimum. Rather, there are a number of local minima to which almost all conventional retrieval algorithms converge. In this work, we develop a new (to our knowledge) retrieval algorithm that employs the numerical method known as simulated annealing with an innovative "temperature" schedule. This study is limited only to spherical particles with a concentric shell and to cases in which the diameter of both the core and the coated particle are known. We find that when the top ranking particle sizes according to their information content are combined from separate experiments to make up the particle size distribution, the simulated annealing retrieval algorithm is quite robust and by far superior to a greedy random perturbation approach often used.     

Enhanced hydrogen generation from aluminum–water reactions

Hydrogen production from the reaction of aluminum powder with liquid water is investigated for nano- and micron-sized spherical aluminum powders over the 20–200 °C temperature range. The maximum hydrogen production rate increases with increasing temperature and decreasing particle size, consistent with a surface reaction controlled by Arrhenius kinetics. The maximum hydrogen production rate normalized by surface area is universal, and an expression is proposed that predicts the maximum rate for variable powder sizes and temperatures. The hydrogen yield increases with increasing temperature and decreasing particle size. Ultrasonic agitation of the mixture increases the hydrogen production rate and total hydrogen yield, and appears to be a promising reaction-enhancing technique. The finite hydrogen yield observed for larger particles and lower temperatures suggests that the reaction is inhibited after it progresses a certain depth into the particles, here termed the penetration thickness. The penetration thickness increases with temperature and is independent of particle size.     

Distribution of Trogoderma granarium (Col. Dermestidae) at constant humidity and in gradient of humidity

The distribution of males and females of Trogoderma granarium beetles in a humidity gradient and at constant humidity was examined. Distribution was not uniform at constant humidity as the beetles usually aggregated at the margins of the apparatus. In a gradient the beetles collected most abundantly where the humidity was low.

The initial distribution of beetles at the beginning of the experiment (whether located at the centre or dispersed uniformly along the instrument) influenced the response and the subsequent behaviour. The response vs. time curve indicates an excessive activity in the different humidity regions in the 10–100 per cent range and a decrease in response in each humidity region with time. At 0 per cent r.h. the activity appears to be normal along the entire instrument and the response increases systematically with time. Aggregation due to an olfactory factor influences the humidity reaction of Trogoderma granarium beetles.     

Furocoumarins in shoots ofPituranthos triradiatus (Umbelliferae) as protectants against grazing by hyrax (Procaviidea:Procavia capensis syriaca)

Pituranthos triradiatus (Umbelliferae) in the Negev desert of Israel is rarely grazed and when grazing occurs, it is mostly confined to sprouts. It was hypothesized that furocoumarins accumulating in the older shoots acted as natural protectants against grazing. This was tested using hyrax (Procavia capensis syriaca) for bioassay. This diurnally active herbivore is known to be resistant to various poisonous plants.Tests were conducted in the autumn (November) and summer (June). In November starved hyraxes were offered unlimited amounts of thawed, previously frozen old branches ofP. triradiatus. They consumed an average amount of 3.4 g dry matter/kg body wt. The animals preferred to stay in the sun, and 3–4 hr after feeding, they showed severe photosensitization symptoms: apathy, photophobia, and injuries around the eyes and on the back. During the following 20 hr, four of the five treated animals died. In the second test, the effect of old branches, compared with young ones was evaluated in sunlight and under shade. Only animals that had eaten old branches and had been left in the sunlight developed photosensitization symptoms. Animals offered old shoots consumed smaller amounts than those offered young ones. However, they ingested larger amounts of imperatorin and isoimperatorin. It is suggested that these two furocoumarins induced photosensitization. Under all conditions, the hyraxes ate very small amounts of shoots ofPituranthos, compared with the amount of their usual diet. This suggests the presence of a severe deterrent factor, possibly furocoumarins, in the shoots. Since furocoumarins undergo light-induced cross-linking with DNA strands, it is conjectured that these natural protectants are segregated from regions within the plant where mitosis occurs, and this is why young shoots ofPituranthos contain smaller amounts of furocoumarins and are more susceptible to various herbivores than are old ones.     

Masculine and feminine traits: Their relation to suitedness for and success in training for traditionally masculine and feminine army functions.

Evidence in support of the androgyny, masculinity, and congruence models is compared in a study of 200 men and 299 women training for traditionally masculine and feminine army functions. Ss rated their chances for success in and suitedness for functions for which they were being trained, and responded to the Bem Sex-Role Inventory. At the end of training they were rated by peers and training officers. Men rated themselves more likely to succeed than did women and had higher officer and peer ratings. Suitedness self-ratings were higher for sex-typed and androgynous men and cross-sex-typed women. Androgynous men and women, sex-typed men, and cross-sex-typed women saw themselves as most likely to succeed. Officers' ratings favored the sex-typed. Men and women high in masculinity had better self- and peer ratings than did those low in masculinity. These results lend most support to the masculinity model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)