An experimental model of a 2kw, 2500 volt power converter for ion thrustors using gate controlled switches in two phase-shifted parallel inverters summary report

Power converter for ion thrustors using electronic gate controlled switches in two phase-shifted parallel inverter

Sex Differences in Associative Structure

First, the history of the concept of associative structure was traced, and various methods of its assessment were reviewed. Included, also, was a survey of word association literature, with emphasis on the most recent studies. Three separate studies followed which were diverse techniques for the assessment of sex differences in associative structure, plus suggestions of some possible reasons--both proximate and remote--for these differences. The first procedure consisted of an investigation of the Jenkins and Palermo Word Association Norms with respect to sexually distinct responses. This revealed many significantly differing responses, and suggested that the differences were the result of a differential emphasis in associations rather than an absolute dissimilarity in the composition of their respective associative structures. The second experiment was characterized by the administration of a multiple choice questionnaire derived from the findings just mentioned. Three age groups of Ss were employed: elementary school (third grade), high school (freshmen), and college students. The differences anticipated by the results of the first study were generally confirmed with the added finding that such divergencies increased as a function of age. A third experiment was undertaken employing a procedure similar to the one used by the television game of Password. This is a word association game in which one member of a pair team is required to give associations to a clue word until his partner is able to identify the clue word. Ss were drawn from the same age levels as those recruited in the second experiment. Findings were: (1) same sexed pairs are more facile at achieving a solution in such a situation than are different sexed pairs, and (2) females are superior to males in arriving at correct responses in this context. The predicted age effects (to parallel the intensification of effect found with increasing age in Experiment II), oddly, did not occur, and potential reasons for this are discussed. A general overview is provided, along with suggestions for the direction(s) future research might take

Chemical Comparison of Two Ecotypes of Loblolly Pine (Pinus Taeda L.)

Loblolly pine from the continuous range in east Texas was compared with an apparently drought-resistant ecotype, the so-called "Lost pines" or "Bastrop pines." The Bastrop pines are found in a small area of central Texas isolated from the rest of the loblolly range, and in a region receiving considerably less rainfall. Determinations made were: holocellulose, alpha cellulose, ash, specific gravity, and percentages of earlywood and latewood. Nutrient analyses for levels of sodium, potassium, calcium, magnesium, zinc, manganese, and copper were also performed. It was found that the earlywood of the east Texas population had significantly greater levels of holocellulose and alpha cellulose. Regression analyses were performed relating the nutrient values to the chemical components. The appearance of potassium and magnesium in these equations, for the Bastrop pines, may indicate physiological adaptation to the more xeric environment

Efficacy of phenothiazine in the treatment of sheep for control of internal parasites

"February, 1946."Treating ewes once in December and once the following March with a full dose of liquid phenothiazine and every 28 days thereafter with 1 1/2 per cent copper sulphate until the following December did not control nodular worm infestation even though at the beginning of the experiment the sheep were placed upon clean pasture.Treating sheep with liquid phenothiazine every four weeks from December to March (giving a total of four treatments) and then giving them 1 1/2 per cent copper sulphate every 28 days did not control nodular worm infestations. The 1 1/2 per cent copper sulphate solution was found very satisfactory in keeping the lambs free from Haemonchus contortus. Treating sheep with liquid phenothiazine every four weeks from December to early April and then allowing them access to pheno-thiazine-salt mixture (1 part phenothiazine to 10 parts salt) was very satisfactory in controlling nodular worm infestation. This method of handling sheep held the Haemonchus contortus infestation down to an average of about 19 per lamb. This same method of handling did not satisfactorily control ostertagia, nematodirus, cooperia or tapeworms. Whipworm counts were not materially different in any of the three experiments. Average weight of the lambs was very much higher in Experiment III when the sheep had access to phenothiazine and salt mixture than it was in Experiments I and II. Phenothiazine has not been found toxic to sheep either in a 1 to10 phenothiazine-salt mixture or when the medicine has been given as a drench every 28 days throughout the entire year. The use of phenothiazine has not interfered with breeding efficiency. Worm egg counts by the flotation method have not contributed any aid in this study, but would be useful in sheep infested with only one species of parasite or with species that can be definitely identified by microscopic examination alone

DDFT calibration and investigation of an anisotropic phase-field crystal model

The anisotropic phase-field crystal model recently proposed and used by Prieler et al. [J. Phys.: Condens. Matter 21, 464110 (2009)] is derived from microscopic density functional theory for anisotropic particles with fixed orientation. Further its morphology diagram is explored. In particular we investigated the influence of anisotropy and undercooling on the process of nucleation and microstructure formation from atomic to the microscale. To that end numerical simulations were performed varying those dimensionless parameters which represent anisotropy and undercooling in our anisotropic phase-field crystal (APFC) model. The results from these numerical simulations are summarized in terms of a morphology diagram of the stable state phase. These stable phases are also investigated with respect to their kinetics and characteristic morphological features.Comment: It contain 13 pages and total of 7 figure

The effects of blur and size on monocular and stereoscopic localization

AbstractMonocular localization of non-abutting stimuli and stereoscopic localization of the same second-order targets are performed with the same precision (Wilcox, L.M. & Hess, R.F. (1996) Is the site of non-linear filtering in stereopsis before or after binocular combination? Vision Research, 36, 391–399). Further, both tasks show a similar dependence on the scale of the stimulus. Since prior studies used Gaussian-enveloped stimuli, modifications of stimulus scale produced concurrent changes in edge blur. The experiments reported here assess the relative contributions of size and blur to the observed dependence on envelope scale for both monocular localization and stereoacuity. Stereoacuity for first-order targets was found to be an order of magnitude better than stereoacuity for second-order targets and monocular acuity for both first- and second-order targets. Further, while first-order stereopsis was found to depend solely on blur, second-order stereoacuity and monocular acuity were affected by both size and blur. These results suggest that while stereoacuity for first-order stimuli may be determined by a correlative process limited by early additive noise, stereoacuity for second-order stimuli and monocular acuity for non-abutting targets are more likely limited by stimulus-dependent spatial subsampling

Abundant and equipotent founder cells establish and maintain acute lymphoblastic leukaemia

High frequencies of blasts in primary acute lymphoblastic leukaemia (ALL) samples have the potential to induce leukaemia and to engraft mice. However, it is unclear how individual ALL cells each contribute to drive leukaemic development in a bulk transplant and the extent to which these blasts vary functionally. We used cellular barcoding as a fate mapping tool to track primograft ALL blasts in vivo. Our results show that high numbers of ALL founder cells contribute at similar frequencies to leukaemic propagation over serial transplants, without any clear evidence of clonal succession. These founder cells also exhibit equal capacity to home and engraft to different organs, although stochastic processes may alter the composition in restrictive niches. Our findings enhance the stochastic stem cell model of ALL by demonstrating equal functional abilities of singular ALL blasts and show that successful treatment strategies must eradicate the entire leukaemic cell population

Rapid ecological assessment of wasp fauna (Hymenoptera: Aculeata) of the Serra do Divisor National Park, Acre, Brazil

O Parque Nacional da Serra do Divisor (PNSD), localizado a noroeste do Estado do Acre, é considerado uma das áreas de maior diversidade da Amazônia. A importância de se considerar insetos em programas de conservação tem sido muito enfatizada. Vespas solitárias e sociais são componentes muito importantes dos ecossistemas, devido à posição que ocupam nas redes alimentares. Esse trabalho teve como objetivo realizar uma avaliação ecológica rápida da fauna de vespas do PNSD, para subsidiar a elaboração de um plano de manejo do referido parque. A amostragem foi realizada em 12 sítios de coleta, situados no interior de oito tipologias de vegetação. Os insetos foram coletados através de armadilhas Malaise, as quais foram expostas em todos os sítios por 24 horas, totalizando 288 horas de amostragem. Foram consideradas nas análises vespas das famílias Chalcididae, Eucharitidae, Evaniidae, Mutillidae, Pompilidae, Crabronidae e Vespidae. Ao todo, foram coletados 366 indivíduos distribuídos em 40 gêneros e 85 espécies. Os gêneros Ephuta (Mutillidae), Trypoxylon (Crabronidae) e Conura (Chalcididae) foram os mais ricos em espécies. Os sítios localizados na região norte do PNSD, considerada zona intangível e zona primitiva, foram os mais ricos em espécies. Cerca de 65% das espécies foram exclusivas a um único sítio, o que significa que as amostras possuem pequena similaridade faunística. Algumas espécies coletadas são consideradas raras.The Serra do Divisor National Park (PNSD), located at the northwest of Acre State, Amazonia, is considered an area of great biodiversity. The question of considering insects in conservation programs. Solitary and social wasps are important components of the terrestrial ecosystems due to their position in trophic webs. The present study aimed at making a rapid ecological assessment of the wasps from the PNSD in order to support the elaboration of a conservation and management plan for that park. The insects were sampled in 12 sites located in eight forest types by Malaise traps that operated in each for 24 hours, totaling 288 hours of sampling. The results on the families Chalcididae, Eucharitidae, Evaniidae, Mutillidae, Pompilidae, Crabronidae and Vespidae are presented here. On the whole, 366 wasps were collected representing 40 genera and 85 species. The genera Ephuta (Mutillidae), Trypoxylon (Crabronidae) and Conura (Chalcididae) were the most specious. The sites situated at the northern region of the PNSD, the intangible and primitive zones, were the most species rich. Some collected species were considered rare and about 65% of species were exclusive to only one site. This means that the samples have little faunal similarity.Fundação S.O.S

RESEARCH BRIEF: An Examination of the Social and Clinical Influences in Prostate Cancer Treatment in African American and White Men

BACKGROUND: The death rate for prostate cancer (PrCA), the most commonly diagnosed cancer in African-American (AA) men, is twice the rate of European-American (EA) men. AA men in South Carolina have the highest age-adjusted death rate in the nation. Studies have shown that treatment offered to AA men with PrCA is systematically different from that offered to EA men. METHODS: Surveys were mailed to 1,866 men in South Carolina with a diagnosis of PrCA. South Carolina men diagnosed with PrCA between 1996 and 2002 were eligible to participate. We performed a descriptive assessment of the factors that influenced PrCA treatment decisions. RESULTS: The treatment choices of AA men were significantly more likely to be influenced by pain and significantly less likely to be influenced by potential for cure compared to EA men. CONCLUSIONS: Providers must be cognizant of the factors that influence treatment, particularly in AA men. Despite the national undertaking to eliminate health disparities, the United States is far from implementing a comprehensive focus on the health of AA men, despite their elevated PrCA morbidity and mortality rates