The interaction of test anxiety and success-failure experiences in determining children's arithmetic performance.

Studied the effects of the motives to approach success and to avoid failure in 60 5th and 6th grade boys and girls of low, middle, and high levels of test anxiety (Test Anxiety Scale for Children and Lie Scale for Children). Ss performed addition problems under 1 of 2 conditions: a mixed condition involving two-thirds success and one-third failure under time pressure and a success only condition in which all problems attempted were completed. As predicted, high anxious Ss, when compared to less anxious Ss on response rate, errors, and cheating, showed markedly inferior performance in the mixed condition, but comparable and improved performance in the success only condition. Findings indicate that anxious children perform poorly due to motivational difficulties rather than to learning deficiencies, and that their abilities are systematically underestimated by many achievement and educational testing procedures. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two-dimensional analysis of j.f.e.t. structures containing a low-conductivity substrate

It is shown that j.f.e.t. structures containing a semiconductor substrate can sometimes exhibit a substantially lower saturation resistance than structures containing an ideally insulating substrate. This characteristic is attributed to velocity-limited carrier transport, in conjunction with the spreading of majority carriers into the semiconductor-substrate material.     

Enhancement by hyperthermia of the in vitro cytotoxicity of mitomycin C toward hypoxic tumor cells

Mitomycin C and hyperthermia are both toxic to chronically hypoxic EMT6 tumor cells. Combinations of this drug and heat were tested in vitro in normally aerated and chronically hypoxic EMT6 mouse mammary tumor cells to establish whether greater than additive cytotoxicity could be achieved by combined treatment. Cell survival was measured at four concentrations of mitomycin C (0.01, 0.1, 1.0, and 10 microM) at 37 degrees or at elevated temperatures (41, 42, and 43 degrees) for durations of 1, 2, 3, and 6 hr. At 42 degrees, exposure to mitomycin C for 3 and 6 hr produced a 2- to 3-fold increase in hypoxic tumor cell kill at all drug concentrations over that expected for strict additivity. A 15-fold enhancement in the kill of hypoxic tumor cells was obtained at 1.0 and 10 microM mitomycin C at 43 degrees for 6 hr of exposure. Under most conditions, additivity was observed for the antibiotic and heat in oxygenated cells, except at 43 degrees with 0.01 and 0.1 microM mitomycin C following 3 and 6 hr of treatment, conditions under which a 5- to 10-fold potentiation of tumor cell kill was obtained. The rate of formation of reactive metabolites from mitomycin C under anaerobic conditions in EMT6 cell-free preparations was measured. A 30 to 50% increase in alkylating activity was observed at elevated temperatures, suggesting that the enhanced cytotoxicity of mitomycin C with heat toward hypoxic cells may, in part, be due to an increase in activation of the drug.     

Evidence of hydrogen embrittlement of tungsten carbide

Tungsten carbide vessels containing materials at high temperature and high pressure are used in many laboratories. We note that any oils at medium to high temperature which can break down and liberate hydrogen cause rapid failure of the pressure vessel, whereas perfluorated kerosenes used as lubricants inside a pressure vessel give sharply increased life of the vessel.     

Studies on the combined effect of gamma radiation and cooking on the nutritional value of fish

The effect of irradiation (0·6 Mrad), cooking and a combination of both treatments has been measured on the protein nutritive value and on the B-complex vitamins, nicotinic acid, riboflavin and thiamine in cod fish fillets. Microbiological assay methods were used throughout. Protein nutritive value was unaffected by irradiation, whereas cooking caused a 9% loss; this loss was not increased by prior irradiation treatment. Irradiation did not affect nicotinic acid and a 4% loss caused by cooking was again not increased by a combination of treatments. Riboflavin was reduced 6% by radiation, 9% by cooking, and 16% after both treatments, whilst for thiamine the losses were 47% by radiation, 10 % by cooking and 54% by combined treatment. It was concluded that irradiation followed by cooking produced a total loss which was the sum of the losses produced by each treatment. The importance of loss of nutrients in fish due to radiation processing is discussed.     

The system approach: A preliminary exploratory study of the relation between team composition and financial performance in business games.

Asked 16 3-5 man self-organizing teams, composed to vary on a dimension of conceptual complexity of the individual members, to compete in a laboratory-based business game. Competitive performance was measured in terms of profit or loss accumulated over a 12-wk period of operations. Variation in team size (3-5 members) was not related to performance. The primary composition variable, conceptual complexity, as measured by a Paragraph Completion Test, was significantly related to financial performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The synthesis of an isobutylene-α-methylstyrene block copolymer with olefinic head-group: (CH3)2C=CHCH2-PIB-b-PαMeSt

Summary The title head-functionalized block copolymer was synthesized by first preparing a polyisobutylene carrying a (CH₃)₂C=CH₂-head-group and -Cl end-group, and subsequently starting the block copolymerization of -methylstyrene from the -Cl terminus.7th in the series: Cationic Polymerization with Boron Halides.     

Rat endometrial Vdup1 expression: changes related to sensitization for the decidual cell reaction and hormonal control

To study the effect of re-immunization against inhibin on ovarian response and hormonal profiles, Japanese beef heifers (n = 5) were re-immunized three times with inhibin vaccine (recombinant ovine inhibin alpha-subunit in oil emulsion, 125 microg ml(-1)) one year after the primary immunization. Control heifers (n = 5) were injected with placebo (Montanide: Marcol adjuvant alone). Oestrous cycles were synchronized by using prostaglandin F2alpha (PGF2alpha) and ovarian response was monitored daily by ultrasonography. Blood samples were collected by jugular venipuncture for assessment of hormonal levels and inhibin antibody titres. In contrast to controls, inhibin re-immunized heifers generated antibodies against inhibin rapidly reaching a peak level 9 days after the first booster injection. The mean concentrations of FSH in re-immunized cows increased significantly in comparison with controls. In addition, there was a significant increase in oestradiol-17beta and progesterone levels in re-immunized cows compared with controls. Inhibin re-immunized heifers had a significant increase in small (> or =4 < 7 mm), medium (> or =7 < 10 mm) and large (> or =10 mm in diameter) sized follicles. Moreover, the mean ovulation rate was 5.0 +/- 1.1 after the third booster injection in re-immunized heifers compared with control heifers (single ovulation). These results clearly demonstrate that re-immunization of inhibin can be used to enhance ovarian follicular development and ovulation rate. Furthermore, the great number of follicles is a potential source of oocytes that could be harvested for in vitro fertilization and embryo transfer programmes.     

1H MAS NMR (magic-angle spinning nuclear magnetic resonance) techniques for the quantitative determination of hydrogen types in solid catalysts and supports

Distinct hydrogen species are present in important inorganic solids such as zeolites, silicoaluminophosphates (SAPOs), mesoporous materials, amorphous silicas, and aluminas. These H species include hydrogens associated with acidic sites such as Al(OH)Si, non-framework aluminum sites, silanols, and surface functionalities. Direct and quantitative methodology to identify, measure, and monitor these hydrogen species are key to monitoring catalyst activity, optimizing synthesis conditions, tracking post-synthesis structural modifications, and in the preparation of novel catalytic materials. Many workers have developed several techniques to address these issues, including 1H MAS NMR (magic-angle spinning nuclear magnetic resonance). 1H MAS NMR offers many potential advantages over other techniques, but care is needed in recognizing experimental limitations and developing sample handling and NMR methodology to obtain quantitatively reliable data. A simplified approach is described that permits vacuum dehydration of multiple samples simultaneously and directly in the MAS rotor without the need for epoxy, flame sealing, or extensive glovebox use. We have found that careful optimization of important NMR conditions, such as magnetic field homogeneity and magic angle setting are necessary to acquire quantitative, high-resolution spectra that accurately measure the concentrations of the different hydrogen species present. Details of this 1H MAS NMR methodology with representative applications to zeolites, SAPOs, M41S, and silicas as a function of synthesis conditions and post-synthesis treatments (i.e., steaming, thermal dehydroxylation, and functionalization) are presented.