微型固体火箭发动机内弹道的数值模拟

随着计算流体力学(CFD)的不断发展, 利用计算机对火箭发动机燃烧室内的气体流动过程进行数值模拟已经成为固体火箭发动机设计中非常重要的一种研究手段, 越来越受到研究人员的重视.文中使用通用流体软件对微型火箭发动机进行内弹道特性的数值模拟进行了研究, 并通过与理论计算所得数值的比较,证明了模拟结果的正确性.     

Social comparison between young children in achievement situations.

Examined the development of children's motivations to socially compare in a situation in which they were free to seek or not seek information about how another child was doing. 16 males and 16 females each at the kindergarten, 1st, and 2nd grade levels were recruited through the newspaper and paid to participate. Pairs of Ss in the same grade worked on a speed task under high- and low-competition conditions. The frequency and duration with which Ss pushed a button to observe their partner's progress on a monitor was the index of the strength of motivation. Results show the expected developmental increase in comparison behavior. Only in 2nd graders did the expected positive relationship between level of competition and performance appear. At the kindergarten level, the means were in the opposite direction, while for the 1st-grade level the relation between competition and performance depended on sex. Results are discussed in terms of alternative predictions derived from theories by L. Festinger (1954) and J. Veroff (1969). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A prescriptive approach for counselor training.

Measured the effectiveness of A. P. Goldstein's (1973) Structured Learning Training (SLT) for teaching confrontation skills to 56 trainees varying in conceptual development (Paragraph Completion Test). Both a self-instruction approach and a standard implementation of SLT were effective for teaching confrontation skills. When trainees' conceptual level (CL) was considered, the approaches proved differentially effective (as measured by pencil-and-paper tests). Self-instruction SLT was more effective with high CL trainees than with low CL trainees; guided-instruction SLT proved more effective than self-instruction SLT with low CL trainees in each treatment. Further, differences due to instructional approach and CL failed to reach significance when the dependent variable was assessed via taped role play. Findings suggest the need for multiple ways of assessing skills as well as multiple approaches for instruction. Further investigation seems necessary to specify the variables involved in maximizing the effect of instruction. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Video-enhanced microscopy with a computer frame memory

Video-enhanced microscopy combined with the use of a computer frame memory extends considerably the useful range of our video enhanced contrast (AVEC) methods for polarizing, double-beam interference and differential interference contrast microscopy. Increased visual contrast is achieved by two stages of amplifications: the first optical, by using high bias retardation settings, and the second electronic. These steps are followed by a reduction of background brightness by means of a clamp voltage applied to a DC restoration circuit of the video camera. One of the limitations of the AVEC method alone is the inevitable appearance under high gain conditions of a pattern of mottle due to inaccessible dirt and defects in the lenses even of high quality. This limitation has been circumvented by storing the mottle pattern in the frame memory (frame store) and continuously subtracting it from each succeeding frame to clear the image. A major gain in image quality has resulted. In polarizing microscopy, the frame memory can be used also to subtract the image at one compensator setting from that at the equivalent setting of opposite sign, thus removing from the final image not only most of the mottle pattern but also the contrast due to the bright-field contrast. In the polarizing microscope, these manipulations of the raw video image make it possible to observe and measure the birefringence of various organelles and elements such as microtubules, intermediate filaments and bundles of as few as a half dozen actin filaments. Since scattered light is also removed from the image, features hidden from view in the unprocessed image become visible. In differential interference microscopy, the AVEC method makes visible (i.e. detectable) many linear elements and particles that are an order of magnitude smaller than the resolution limit and not visible in the optical image. Such features are inflated by diffraction, however, to Airy disk size.     

Developmental changes in predicting recognition memory for semantically related and unrelated sentences.

Examined the development of an awareness (metamemory) of "constructive interference." This is the "fact" that when children and adults are presented a list of semantically related sentences, they later find it more difficult to distinguish old from new instances than when they are presented a list of unrelated sentences. Knowledge of this constructive interference was tested by having 192 11-, 15- and 22-yr-old students first predict recognition and then take an actual recognition test. In independent groups, half of the Ss received lists of semantically related sentences, and half received lists of semantically unrelated sentences. By comparing Ss' predictions with their actual performances across the different groups, it appears that the 11-yr-olds did not comprehend this phenomenon, but the 15- and 22-yr-olds did. That is, older Ss correctly predicted that recognition performance would be poorer for related lists than for unrelated lists. The 11-yr-olds, by contrast, predicted that recognition would be about the same for the 2 kinds of lists. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Increased intrusions during verbal recall in traumatic and nontraumatic lesions of the temporal lobe.

The mesial temporal and lateral frontal lobes were the most common sites of parenchymal abnormality on magnetic resonance imaging (MRI) scans for 12 patients with chronic traumatic brain injury (TBI). Ventricular widening was also common, and 3 patients showed increased size of the upper third ventricle. Of 10 right-handed TBI patients with no evidence of learning disability, 6 showed dominant temporal lesions and 3 showed an increase in the size of the upper third ventricle. Only patients with dominant temporal lesions (4 of 6) exceeded the normal confidence interval (based on 20 non-TBI controls) for intrusion errors on delay trials of the California Verbal Learning Test (CVLT), though other patients also demonstrated impaired recall. The pattern of increased intrusions during CVLT delay trials was confirmed in non-TBI patients who had undergone dominant temporal surgery or had dominant or bilateral temporal lesions, even when frontal changes could be ruled out. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Response of free and esterified plasma cholesterol levels in the mongolian gerbil to the fatty acid composition of dietary lipid

The present study was undertaken to investigate the potential suitability of the Mongolian gerbil as a useful animal model to study the effects of dietary fats on plasma cholesterol levels. Semipurified diets containing either 20% lard, 20% safflower oil, or 19.5% beef tallow +0.5% safflower oil were equalized to contain 0.01% cholesterol and 0.05% plant sterol and were fed for a four week experimental period. The proportions of total calories contributed by fat, protein and carbohydrate (starch/sucrose ratio of 2∶1) were 40, 14 and 46%, respectively, so as to approach the distribution of calories within the average North American diet. Free, esterified, and total plasma cholesterol levels of male gerbils were determined weekly by gas liquid chromatography after drawing blood via a serial sampling technique. After 1, 2, 3, and 4 weeks of feeding the experimental diets, total cholesterol levels were lowest in the safflower oil fed animals; the corresponding values were 19–64% greater in gerbils fed lard and 68–91% greater in those consuming the beef tallow diet. Cholesterol in the free form generally responded more dramatically to the type of dietary lipid than did cholesterol in the ester form. Irrespective of the type of dietary lipid or the length of the feeding trial, 18–23% of the total plasma cholesterol was in the free form and 77–82% was present as the ester. In view of the similarity to the human of the relative proportions of free versus esterified cholesterol, the type of cholesteryl esters, and their response to dietary manipulation, the gerbil appears to be a useful animal model for studying the regulatory effect of dietary lipid on plasma cholesterol levels. Presented in part at the A.O.C.S. Annual Meeting, San Francisco, CA, May 1979.     

Causes and prevention of boating fatalities

The aim of this study was to investigate the causes and prevention of the 333 boating deaths that occurred in Australia over the period 1992-1998. It involved: assessment of the Coroner's findings; review of witness statements, police reports, autopsy findings, search and rescue reports, weather maps and reports; analysis of forensic and scientific data; assessment of photographic evidence; review of other related information. The data were coded according to a recently developed national data standard. It was found that nearly half of the vessels involved had an insufficient number of personal flotation devices for the number of people on board; of all people killed only 9% were wearing them, and survivors were more than two times more likely to have been wearing them. If usage could be increased to 75%, five lives could be saved each year with a cost saving to the Australian community of nearly $8 million. The contribution of alcohol to boating deaths (28% in excess of 0.05g/100ml) was similar to its contribution to road deaths. The sequence of events resulting in a boating death was initiated most often by capsize (36%). Capsize was more likely to involve overloading or improper loading, hazardous wind or sea conditions, and dinghies. Twenty-five percent of the vessels involved in fatalities were dinghies and they were more likely to be overloaded, involve capsize, alcohol, and failure to wear a personal flotation device. Fatalities involving personal watercraft were mainly caused by human factors. Boating causes a significant level of harm to the Australian community measured in terms of mortality. This can be reduced by a concerted effort to address the identified hazards and protective factors.     

Neonatal treatment of rats with diethylstilboestrol (DES) induces stromal-epithelial abnormalities of the vas deferens and cauda epididymis in adulthood following delayed basal cell development

This study investigated whether transient, neonatal (days 2-12) treatment of rats with the potent oestrogen, diethylstilboestrol (DES), altered the structure of the cauda epididymis/vas deferens in adulthood, and if the changes observed related to altered development of basal cells in early puberty. Neonatal treatment with 10 microg DES resulted in the following during adulthood: (a) coiling of the normally straight initial vas deferens, (b) gross epithelial abnormalities, (c) 4-fold widening of the periductal non-muscle layer, (d) infiltration of immune cells across the epithelium into the lumen, and (e) reduction/absence of sperm from the vas deferens lumen. Amongst affected animals>75% exhibited reduced epithelial immunoexpression of androgen receptor and aberrant oestrogen receptor-alpha immunoexpression and 63% exhibited multi-layering of basal cells coincident with increased epithelial cell proliferation. None of the aforementioned changes occurred in rats treated neonatally with 0.1 microg DES.As basal cells play a key role in the development of epithelia such as that in the epididymis and vas deferens, we went on to investigate if neonatal DES treatment affected basal cell development. In controls, basal cells were first evident at day 10 (vas deferens) or day 18 (cauda). Rats treated with 10 microg, but not those treated with 0.1 microg, DES, showed approximately 90% reduction (P<0.001) in basal cell numbers at day 15 and day 18. This decrease coincided with gross suppression of testosterone levels; co-treatment of rats with 10 microg DES+testosterone maintained basal cell numbers at control levels at day 18. However, suppression of testosterone production (GnRH antagonist treatment) or action (flutamide treatment) did not alter basal cell numbers. It is concluded that neonatal exposure to high oestrogen levels coincident with reduced testosterone action results in abnormal changes in the adult cauda/vas deferens that are preceded by delayed differentiation of basal cells. These findings imply a role for androgens and oestrogens in basal cell development and suggest that this may be pivotal in determining normal epithelial (and stromal) development of the cauda/vas deferens.     

Children's generosity as influenced by deservedness of reward and type of recipient.

24 5-6 yr-olds and 24 8-9 yr-olds were given the opportunity to donate money to a charity under conditions varying the characteristics of the recipient (crippled child vs crippled adult) and the situation in which the child acquired the resource for generosity (earned vs windfall). On the basis of previous literature, it was expected that these conditions would affect the age differences often reported in generosity. Contrary to such expectations, there was more generosity toward crippled children than crippled adults across both age groups. There was an increase in generosity with age across conditions, with girls consistently donating more than boys. Methodological issues and reactions to stigmatized others are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)