5 resultados para Black body
em Digital Commons at Florida International University
Resumo:
The permanent pigmentation of the leaves of tropical rain forest herbs with anthocyanin has traditionally been viewed as a mechanism for enhancing transpiration by increased heat absorption. We report measurements to ?+0.1?0C on four Indo-mal- esian forest species polymorphic with respect to color. There were no detectable differences in temperature between cyanic and green leaves. In deeply shaded habitats, any temperature difference would arise from black-body infrared radiation which all leaves absorb and to which anthocyanins are transparent. Reflectance spectra of the lower leaf surfaces of these species re- vealed increased reflectance around 650-750 nm for cyanic leaves compared with green leaves of the same species. In all spe- cies anthocyanin was located in a single layer of cells immediately below the photosynthetic tissue. These observations provide empirical evidence that the cyanic layer can improve photosynthetic energy capture by back-scattering additional light through the photosynthetic tissue.
Resumo:
This thesis traces the mechanisms and sources responsible for the generation of civic social capital (a set of shared norms and values that promote cooperation between groups, enabling them to participate in the political process) by black churches in West Perrine, Florida. Data for this thesis includes over fifty interviews and participant observations, archival records, newspaper articles, and scholarly journals. ^ Despite the institutional racism of the first half of the twentieth century, many blacks and whites in Perrine developed levels of trust significant enough to form an integrated local governing body, evidence of high levels of csc. At mid-century, when black and white interactions ceased, Perrine's csc decreased, leading to the deterioration of Perrine's social and physical conditions. Perrine's csc increased in the 1980s by way of broad-based coalitions as Perrine's churches invested their csc in an effort to eradicate crime, clean up its neighborhood, and win back its youth. ^
Resumo:
This study tests Ogbu and Simons' Cultural-Ecological Theory of School Performance using data from the Progress in International Reading Literacy Study of 2001 (PIRLS), a large-scale international survey and reading assessment involving fourth grade students from 35 countries, including the United States. This theory argues that Black immigrant students outperform their non-immigrant counterparts, academically, and that achievement differences are attributed to stronger educational commitment in Black immigrant families. Four hypotheses are formulated to test this theory: Black immigrant students have (a) more receptive attitudes toward reading; (b) a more positive reading self-concept; and (c) a higher level of reading literacy. Furthermore, (d) the relationship of immigrant status to reading perceptions and literacy persists after including selected predictors. These hypotheses are tested separately for girls and boys, while also examining immigrant students' generational status (i.e., foreign-born or second-generation). ^ PIRLS data from a subset of Black students (N=525) in the larger U.S. sample of 3,763 are analyzed to test the hypotheses, using analysis of variance, correlation and multiple regression techniques. Findings reveal that hypotheses a and b are not confirmed (contradicting the Cultural-Ecological Theory) and c and d are partially supported (lending partial support to the theory). Specifically, immigrant and non-immigrant students did not differ in attitudes toward reading or reading self-concept; second-generation immigrant boys outperformed both non-immigrant and foreign-born immigrant boys in reading literacy, but no differences were found among girls; and, while being second-generation immigrant had a relatively stronger relationship to reading literacy for boys, among girls, selected socio-cultural predictors, number of books in the home and length of U.S. residence, had relatively stronger relationship to reading self-concept than did immigrant status. This study, therefore, indicates that future research employing the Cultural-Ecological Theory should: (a) take gender and generational status into account (b) identify additional socio-cultural predictors of Black children's academic perceptions and performance; and (c) continue to build on this body of evidence-based knowledge to better inform educational policy and school personnel in addressing needs of all children. ^
Resumo:
Flavonoids are a class of over 6,500 plant metabolites that have been associated with reduced mortality from cardiovascular disease. A cross-sectional analysis of dietary flavonoids and serum cholesterol in 507 Blacks with and without type 2 diabetes (258 Haitian-Americans and 249 African-Americans) showed differences by ethnicity and diabetes status. Haitian-Americans consumed more of most flavonoids as compared to African-Americans. Individuals with type 2 diabetes consumed less of most flavonoids as compared to those without diabetes. Flavonoids were differentially associated with low-density lipoprotein cholesterol (LDL) and high-density lipoprotein cholesterol (HDL) by diabetes status. Flavanones were associated with lower LDL for participants without diabetes and higher LDL for those with diabetes, independent of ethnicity and adjusted for age, gender, cholesterol medications, daily energy, dietary fat, body mass index (BMI), and smoking. Flavan-3-ols were positively related to LDL while polyflavonoids (theaflavin and polymers, proanthocyanidins) were inversely related to LDL for the group without diabetes only. Higher anthocyanidins and flavan-3-ols and lower polyflavonoids were associated with higher HDL (same adjustments) for those without diabetes, whereas no flavonoids were associated with HDL for individuals with type 2 diabetes.
Resumo:
The purpose of this study was to determine the racial and ethnic differences on body image perceptions and weight concerns of fourth grade girls. A purposive sample of 182 fourth grade girls were eligible to participate, 166 were included in the data analysis. The Children's Eating Attitude Test (ChEAT) and a Dieting and Demographic Questionnaire (DDQ) were used to determine eating attitudes of fourth grade girls. A pictoral instrument that was modified from the original was used to assess body image. Anthropometric data was assessed and body mass index (BMI) values were used to classify subjects into percentiles. Results revealed that 56% of all fourth grade girls studied wanted to be thinner and 53% had tried to lose weight. Significantly more non-Hispanic white (NHW) girls reported wanting to be thinner than non-Hispanic black (NHB) and H girls (65.5% vs.32% and 47%, respectively, P=0.005) No significant racial/ethnic differences were revealed for the ChEAT scores. However, 19% of all subjects studied fell into the category indicative of anorexia nervosa. H girls who were less than the 85" %tile for BMI chose significantly smaller figures as their perceived body image (3.5±0.7) than both NHB and NHW girls (4.0±0.6 and 3.9±0.5, respectively, P<0.01). These findings demonstrated that weight concerns were prevalent among girls ages 9- 11 years. NHW and H girls may have more concerns about their body size and shape than their NHB counterparts. Implementing intervention programs at an early age may prevent eating disorders in adolescence and adulthood.