Reading comprehension level and development in native and language minority adolescent low achievers:Roles of linguistic and metacognitive knowledge and fluency

In a longitudinal design, we measured 50 low-achieving adolescents’ reading comprehension development from Grades 7 to 9. There were 24 native Dutch and 26 language minority students. In addition, we assessed the roles of (a) linguistic knowledge, (b) metacognitive knowledge, and (c) reading fluency in predicting both the level and growth of reading comprehension. Students improved in reading comprehension, the language minority students more so than the native Dutch students. We can explain the level of reading comprehension by linguistic and metacognitive knowledge, whereas most fluency-related predictors appeared to be of minor importance. We can hardly explain the growth in reading comprehension by the predictors. Nevertheless, we found a significant interaction indicating that growth in vocabulary explained growth in reading comprehension for the language minority students. This finding seems to suggest that language minority students profit from gains in vocabulary, more so than native students

Writing proficiency level and writing development of low-achieving adolescents: The roles of linguistic knowledge, fluency, and metacognitive knowledge

In a longitudinal design, 51 low-achieving adolescents' development in writing proficiency from Grades 7 to 9 was measured. There were 25 native-Dutch and 26 language-minority students. In addition, the roles of (i) linguistic knowledge, (ii) metacognitive knowledge, and (iii) linguistic fluency in predicting both the level and development of writing proficiency were assessed. Low-achieving students improved in writing proficiency, the language-minority students more so than the native-Dutch students. Regarding the level of writing proficiency, individual differences between low-achieving adolescents could be accounted for by receptive vocabulary, grammatical knowledge, and speed of sentence verification, suggesting that these are important components in low-achieving adolescents' writing. Regarding development in writing proficiency, grammatical knowledge predicted variation between lowachieving students. Explanations and educational implications of these findings are discussed

Nuchal translucency as a method of first-trimester screening for aneuploidy

Objective. To determine the effectiveness of nuchal translucency (NT) screening in predicting aneuploidy and structural abnormalities in a South African population. Study design. Descriptive study. Setting. Chris Hani Baragwanath Hospital fetal medicine unit. Outcome measures. An adjusted risk was derived from the combination of maternal age-related risk and the risk derived from NT screening. A positive screen was denoted by an adjusted risk of more than 1/300 and a negative screen by an adjusted risk of less than 1/300. In order to determine the number of undiagnosed abnormalities in the group, all babies were examined by a paediatrician at birth to detect and describe dysmorphic features. Results. A total of 428 patients underwent first-trimester screening between July 2003 and July 2005. Three per cent were lost to follow-up. Of the 415 patients analysed, 59 screened positive and 356 screened negative. The mean age for both groups of patients was 30.1 years. Of the 57 patients who screened positive, 24 elected to have chorionic villus sampling (CVS). This resulted in the detection of 6 chromosomal abnormalities and 2 structural abnormalities. Among the remaining 356 patients, who had screened negative, 2 had an increase in the adjusted risk when the risk was compared with the background risk, and 1 chromosomal abnormality was detected in this group; 8 elected to have CVS because of a previous history of a chromosomal abnormality, and there were no abnormalities among them. Conclusions. The use of these screening methods has enabled prenatal karyotyping to become cost effective, and allows concentration on pregnancies at highest risk for chromosomal abnormalities, regardless of age.South African Medical Journal Vol. 98 (4) 2008: pp. 295-29

Cervical intra-epithelial neoplasia in HIV-positive women after excision of the transformation zone – does the grade change?

Objective. After previously reporting the presence of disease by cytology findings after treatment for cervical intra-epithelial neoplasia (CIN) in 64.6% of HIV-infected women and in 13.0% of HIV-negative women, we aimed to determine the severity of cytological disease after treatment in HIV-infected women.Methods. We studied HIV-infected (N=571) women treated at the Colposcopy Clinic at Chris Hani Baragwanath Hospital, Gauteng, between April 2003 and December 2006. We compared the initial histology results with Pap smears .6 months later, and evaluated factors associated with reduction in the grade of disease.Results. Mean age was 36.68 (SD+7.33) years; mean parity was 2 (SD+1.46); mean CD4+ count was 242.70 cells/ƒÊl (SD+187.56); 262 (45.80%) were receiving antiretroviral treatment. Persistent disease was detected on the repeat Pap smear in 199 (65.03%); of these, 223 (72.88%) were of a lesser grade than in the original histology results. Of the 152 with histologically confirmed CIN3, 67 (44.08%) had improved to a lesser grade, and 54 (44.63%) had normal cytology results. Among the latter two subject groups (n=141) who had CIN2 histologically, 91 (64.53%) had improved, 29 (20.57%) remained unchanged, and 20 (14.88%) had CIN3; 13 (4.25%) patients with CIN1 returned for follow-up; 11 (84.62%) of these had normal Pap smears and 2 (15.38%) had CIN3.Conclusion. Recurrences were of a lesser degree than initial histology results. This reduction in the grade of disease was related to CD4+ count, complete excision and parity. Antiretroviral therapy use did not improve outcome, perhaps owing to low initial CD4 counts

Quantitative risk assessment of FMDV introduction in a FMD free country through bone-in beef and offal importation from a FMD free with vaccination country/zone

Quantitative risk assessment was used to estimate the risk of introducing foot-and-mouth disease (FMD) through bone-in beef from Argentina (FMD-free with vaccination status) into other FMD-free countries. A stochastic model was built to characterize all the steps from primary production to bone-in beef export and introduction into an FMD-free country. The probability that bone-in beef from at least one animal infected with the FMD virus (FMDV) was exported during a year was 5.27 × 10−3 (95% CI <10−10 – 5.19 x 10–2) or in other words one case in 190 years. The risk of FMDV introduction was sensitive to the probability of an outbreak occurring in Argentina (r [Spearman´s rank correlation] = 0.99) and the number of herds affected during an outbreak (r = 0.10). Additionally, the probability that susceptible animals in the importing country came into contact with infective material (bones) and generated an outbreak was 6.16 × 10−4 (95% CI <10−10 – 6.20 ×10−3) or one FMD outbreak every 1623 years on average. Based on the quantitative risk assessment results, the probability of FMDV introduction into a FMD-free country where vaccination is not practiced from a FMD-free country where vaccination is practiced associated with bone-in beef trade from Argentina was negligible. The risk of an FMD outbreak caused by the potential introduction of the FMDV was associated with the existing conditions in the country. Thus, maintaining the FMD-free status with or without vaccination would not be relevant.Fil: Brusa, Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; ArgentinaFil: Durrieu, M.. No especifíca;Fil: Van Gelderen, C. J.. No especifíca;Fil: Signorini Porchietto, Marcelo Lisandro. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Santa Fe. Instituto de Investigacion de la Cadena Lactea. - Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Santa Fe. Estacion Experimental Agropecuaria Rafaela. Instituto de Investigacion de la Cadena Lactea.; ArgentinaFil: Schudel, A.. No especifíca

Electronic Structure of the Complex Hydride NaAlH4

Density functional calculations of the electronic structure of the complex hydride NaAlH4 and the reference systems NaH and AlH3 are reported. We find a substantially ionic electronic structure for NaAlH4, which emphasizes the importance of solid state effects in this material. The relaxed hydrogen positions in NaAlH4 are in good agreement with recent experiment. The electronic structure of AlH3 is also ionic. Implications for the binding of complex hydrides are discussed.Comment: 4 pages, 5 figure

CaB_6: a new semiconducting material for spin electronics

Ferromagnetism was recently observed at unexpectedly high temperatures in La-doped CaB_6. The starting point of all theoretical proposals to explain this observation is a semimetallic electronic structure calculated for CaB_6 within the local density approximation. Here we report the results of parameter-free quasiparticle calculations of the single-particle excitation spectrum which show that CaB_6 is not a semimetal but a semiconductor with a band gap of 0.8 eV. Magnetism in La_xCa_{1-x}B_6 occurs just on the metallic side of a Mott transition in the La-induced impurity band.Comment: 4 pages, 1 postscript figur