On-line recording of solar cooker use rate by a novel metering device: Prototype description and experimental verification of output data

A metering device for the determination of solar cooker use rate is presented. The device records food temperature, ambient temperature and irradiance. Automatic data evaluation yields the number of cooking cycles, cooking time, food “thermal mass”, as well as the impact on fuel consumption and GHG emission compared to other cooking techniques. Metering results are compared with actual conditions for box-type and concentrating solar cookers and found to be in agreement.     

The development impact of solar cookers: A review of solar cooking impact research in South Africa

Solar cooking is often considered “a solution looking for a problem”. Solar cookers have long been presented as an interesting solution to the world's problem of dwindling fuel wood sources and other environmental problems associated with wood fuel demand for cooking. However, recent GTZ field work in South Africa showed different benefits instead: the use of solar cookers resulted in appreciable fuel and time savings as well as increased energy security for households using commercial fuels. These observations are based on field tests in South Africa that started in 1996 to investigate the social acceptability of solar cookers and to facilitate local production and commercialisation of the technology. Impact studies and use rate studies have been carried out by a number of different organisations since the inception of the project and although commercialisation of the technology has not been achieved to its fullest potential, impact studies indicate that solar cookers have a positive development impact on households through fuel-, energy- and time savings. The article aims to summarise the findings of the various studies and present an overview of use rates and impact data. A variety of factors influence solar cooker use rates, which in turn determine impacts. Some factors are related to the user, some to the environment in which the cooker is used and some to the cooker itself. Ultimately, the data shows that on average, only 17% of solar cooker owners do not use their stoves after purchase and that active solar cooker users utilise their stoves on average for 31% of their cooking incidences. Since the majority of solar stove buyers actually use their stoves and obtain real benefits, this suggests that that solar cookers are indeed not a solution looking for a problem but a solution worth promoting.     

Conflict in families of adolescents: The impact on cohesion and power structures.

Investigated 3 characteristics (locus, content, and frequency) of conflict (CF) in families of adolescents. Ss were 134 parents and 170 early (mean age 11.5 yrs), 109 middle (mean age 16.3 yrs), and 47 late (mean age 18.7 yrs) adolescents. Ss reported family CF on T. M. Gehring and S. S. Feldman's (see record 1989-14119-001) Family System Test and in an interview. CF in marital (MADs) and parent–adolescent dyads (PADs) was frequently reported. Across adolescence, reports of PAD CF increased, especially those related to autonomy. CF decreased cohesion and changed power relations in the representations of family structure. CF in the MAD was related to decreased cohesion and increased cross-generational coalitions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of Rat Hepatic Cholesterol Biosynthesis During Skim Milk Versus Whey Permeate Ingestion

Whey permeate is an ultrafiltrate of whey that is devoid of protein but contains lactose, salts, and other soluble low molecular weight compounds. These experiments compared cholesterol concentrations of blood plasma, hepatic lipids, and hepatic cholesterol biosynthesis of rats ingesting skim milk powder versus whey permeate powder. Groups of young male rats weighing 90 to 92 g were fed a casein-based diet into which skim milk powder or whey permeate powder was incorporated isocalorically. No effects of skim milk or whey permeate on plasma cholesterol concentrations were observed at any time during 5-wk of feeding. However, 3-hydroxy-3-methylglutaryl coenzyme A reductase activity was increased by either skim milk or whey permeate feeding. Hepatic cholesterol, triglyceride, and phospholipid concentrations at wk 5 were unchanged. Plasma and hepatic cholesterol responses of rats to whey permeate ingestion are similar to those that occur with skim milk consumption, and plasma and hepatic cholesterol concentrations do not reflect necessarily an increase in hepatic cholesterol biosynthesis.     

Does being good make the grade? Social behavior and academic competence in middle school.

Examined relations of prosocial and antisocial classroom behavior to academic achievement, taking into account the possible mediating effects of academically oriented classroom behavior and teachers' preferences for students. Correlational findings based on 423 students in 6th and 7th grade indicated that prosocial and antisocial behavior are related significantly to GPA and standardized test scores and to teachers' preferences for students and academic behavior. Results from multiple-regression analyses suggested that both types of social behavior are significant, independent predictors of classroom grades, even when academically oriented behavior and teachers' preference for students, IQ, family structure, sex, ethnicity, and days absent from school are taken into account. Results of regressions suggested that significant correlations between social behavior and academic outcomes can be explained in part by significant relations between social and academic behavior. The role of social behavior in promoting classroom learning is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relations among family interaction patterns, classroom self-restraint, and academic achievement in preadolescent boys.

Relations among observed family interaction patterns, preadolescent boys' classroom self-restraint, and academic achievement were studied in a sample of 65 intact families. In contrast to previous work in this area, children's social adjustment was introduced as a potential mechanism that mediates the relations between parent–child interactions and academic performance. Correlational results showed significant relations between achievement and all parent–child interaction scores except mother–son hostility. However, regression analyses suggested that the association between father–son interactions and achievement is mediated almost entirely by sons' restraint, whereas the relationships between mother–son interactions and achievement are not. Observed mother–father hostility also appears to be an indirect predictor of sons' academic achievement by way of its association with sons' restraint. These findings are especially important in that they identify social competence in the form of behavioral self-restraint as a noncognitive mediator between the quality of family functioning and academic achievement during early adolescence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Friendships in Middle School: Influences on Motivation and School Adjustment.

In this 2-year longitudinal study (n=242), the authors examined relations of having a reciprocated friend and characteristics of a reciprocated friend to students' social and academic adjustment to middle school. With respect to having a friend, 6th-grade students without friends showed lower levels of prosocial behavior, academic achievement, and emotional distress than did students with reciprocated friendships. Not having a friend in 6th grade also was related to emotional distress 2 years later. Evidence that motivational processes mediate relations between friends' and individuals' prosocial behavior was obtained. For students with reciprocated friendships (n=173). friends' prosocial behavior predicted change in individuals' prosocial behavior in 8th grade by way of changes in goals to behave prosocially. Implications for studying friendship influence in middle school are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Agglomeration and electrical percolation behavior of carbon black dispersed in epoxy resin

In conductive polymer compounds, the filler volume fraction at which a network of touching particles is formed is not a constant but depends on the manufacturing process. By applying three main features—particle-particle interaction, dynamics of agglomeration, and structure of agglomerates—which are well known in colloid science to filled polymers, the electrical percolation behavior can be understood. Thus, it is possible to explain the hitherto found low percolation thresholds of less than 0.5 vol% in carbon-black-filled resins and, hence, further reduce the threshold to 0.06 vol%. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1741–1746, 1997     

Electrically conductive glass fibre reinforced epoxy resin

 The research on an industrially manufactured, electrically conductive glass fibre reinforced epoxy prepreg for aviation applications is reported. In a co-operative effort between Technical University Hamburg-Harburg (TUHH) and Daimler-Benz Aerospace Airbus (DASA) a new glass-epoxy composite with both electrical and good mechanical properties was successfully developed. The electrical conductivity was achieved adding carbon black as a conductive filler into the epoxy matrix and this at a very low level of content. The range of possible applications for this new material is not only limited to aviation. It can also be used in other transport systems or in electric and electronic devices. Received: 21 July 1998 / Accepted: 28 August 1998