1,534 research outputs found

    Youths as behavior change agents in an institution

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    Behavioral studies have shown that youths in various settings can function effectively as behavior change agents. This study used five 15 to 18 year old male youths in a closed institutional setting as behavior change agents for five male Youth Counselors. Youths specified staff behaviors they wanted to change, collected frequency data on each specified staff behavior, and suggested and implemented treatments to change staff behavior. A multiple baseline design across staff members was used to demonstrate the effects of youths\u27 interventions on staff behaviors. Staff increased their frequency of positive verbal comments and decreased their frequency of negative verbal comments and threats .. _regarding loss of privileges following a one-time feedback -from youths regarding staff\u27s baseline frequency_of responses. Two staff members received a second treatment consisting of verbal feedback and praise immediately following each data collection session. This treatment was too short to have an effect on positive and negative verbal comments, but ·appeared to decrease staff\u27s frequency of threats to a near zero rate. Follow-up revealed that frequency of responses did not return to the baseline rate in most cases. Consistent with past studies that have used youths as behavioral change agents, the present findings demonstrate that 11 delinquent youths can be (a) accurate and reliable data collectors, and (b) effective behavior change agents for staff

    Bolt Bearing Behavior of Engineered Wood Composites

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    The goal of this research was to gain a better understanding of the bolt bearing behavior of engineered wood composites made from yellow poplar lumber. Lumber specimens included in this study were laminated veneer lumber, strandbased lumber, yellow poplar lumber, and Douglas-fir larch lumber. Testing followed the half-hole and full-hole configuration as set forth in ASTM Standard D5764 (1998). In a previous study by Wilkinson (1991), a strong correlation was shown between bearing strength perpendicular to grain and bolt diameter. This study supports Wilkinson\u27s finding for bearing strength perpendicular-to-grain based on the half hole test configuration. Other findings in this study indicate there may be a correlation between bolt diameter and bearing strength parallel-to-grain for the half-hole test configuration as well as a correlation between bolt diameter and bearing strength both perpendicular- and parallel-to-grain for the full-hole test configuration. In general, half-hole tests resulted in a greater dowel-bearing strength than full-hole tests, especially for 12.7mm (1/2 in) diameter bolts. Also, engineered wood composites generally provided equivalent or greater dowel-bearing strength in the half-hole configuration and greater dowel-bearing strength in the full-hole configuration when compared to lumber from the same species

    Oxygen isotope composition of living Neogloboquadrina pachyderma (sin.) in the Arctic Ocean

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    Data from the Nansen Basin of the Arctic Ocean are used to investigate the habitat and conditions under which the polar planktic foraminifer Neogloboquadrina pachyderma (sin.) calcifies. The vertical distribution of δ18O values of net-sampled speciments, together with their abundances and proportion of calcification, are compared with δ18O values from both water samples and foraminiferal tests from core-top sediments. Within the Nansen Basin the average depth of habitat of N. pachyderma (sin.) changes from about 150 m in the southern part to about 80 m in the northern. The average depth of calcification, however, in both regimes varies between 100 and 200 m water depth. δ18O data from net sampled N. pachyderma (sin.) are directly reflected in the core-top sediment data, but compared to equilibrium calcite δ18O values derived from measurements of the ambient water, a consistent offset of about 1‰ over all depth intervals is observed. While in the southern part of the Nansen Basin advection through Fram Strait of planktic foraminifers from further south may play a role, the data from the northern part of the Nansen Basin give clear evidence that the observed offset in δ18O values is caused by a vital effect of N. pachyderma (sin.)

    Cannabis legalisation and testing for cannabis use in safety- and risk-sensitive environments

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    The legalisation of cannabis by the High Court of South Africa, which was confirmed by the Constitutional Court, imposes challenges to occupational medical practitioners acting as medical review officers in compliance testing and fit-for-service medical examinations. The lipophilic character of the psychoactive component of cannabis, delta-9-tetrahydrocannabinol (Δ9-THC), and its prolonged elimination half-life, create challenges for the ethically and scientifically correct management of the legal use of cannabis in risk-sensitive environments. Important issues to consider in testing for cannabis use are: the stance of ‘zero tolerance’; screening and confirmation cut-off concentrations; and the bio-matrices used for testing. Constitutional rights relate to privacy, freedom, autonomy, freedom of religion and the equal enjoyment of rights and privileges, which must be balanced against the health and safety of others

    Differential contractile response of critically ill patients to neuromuscular electrical stimulation

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    BACKGROUND: Neuromuscular electrical stimulation (NMES) has been investigated as a preventative measure for intensive care unit-acquired weakness. Trial results remain contradictory and therefore inconclusive. As it has been shown that NMES does not necessarily lead to a contractile response, our aim was to characterise the response of critically ill patients to NMES and investigate potential outcome benefits of an adequate contractile response. METHODS: This is a sub-analysis of a randomised controlled trial investigating early muscle activating measures together with protocol-based physiotherapy in patients with a SOFA score ≥ 9 within the first 72 h after admission. Included patients received protocol-based physiotherapy twice daily for 20 min and NMES once daily for 20 min, bilaterally on eight muscle groups. Electrical current was increased up to 70 mA or until a contraction was detected visually or on palpation. Muscle strength was measured by a blinded assessor at the first adequate awakening and ICU discharge. RESULTS: One thousand eight hundred twenty-four neuromuscular electrical stimulations in 21 patients starting on day 3.0 (2.0/6.0) after ICU admission were included in this sub-analysis. Contractile response decreased from 64.4% on day 1 to 25.0% on day 7 with a significantly lower response rate in the lower extremities and proximal muscle groups. The electrical current required to elicit a contraction did not change over time (day 1, 50.2 [31.3/58.8] mA; day 7, 45.3 [38.0/57.5] mA). The electrical current necessary for a contractile response was higher in the lower extremities. At the first awakening, patients presented with significant weakness (3.2 [2.5/3.8] MRC score). When dividing the cohort into responders and non-responders (> 50% vs. ≤ 50% contractile response), we observed a significantly higher SOFA score in non-responders. The electrical current necessary for a muscle contraction in responders was significantly lower (38.0 [32.8/42.9] vs. 54.7 [51.3/56.0] mA, p < 0.001). Muscle strength showed higher values in the upper extremities of responders at ICU discharge (4.4 [4.1/4.6] vs. 3.3 [2.8/3.8] MRC score, p = 0.036). CONCLUSION: Patients show a differential contractile response to NMES, which appears to be dependent on the severity of illness and also relevant for potential outcome benefits. TRIAL REGISTRATION: ISRCTN ISRCTN19392591 , registered 17 February 201

    Adsorption of Pb on iron oxide colloids as a function of DOM concentration

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    Soil contamination with lead (Pb) is of particular concern for human health, especially with respect to potential transport to the groundwater. Pb can be co-transported with both organic and inorganic colloidal particles in soils. The aim of this study is to determine the interactions between Pb and typical soil colloids such as dissolved organic matter (DOM), goethite colloids, and organic matter coated goethite (OMCG) colloids as well as to investigate the influence of these colloidal particles on the mobility of Pb in soils. For that, experiments were conducted with DOM derived from Fagus sylvatica litter and goethite colloids with mean particle size of 500 nm. The effects of DOM concentration on goethite colloid zeta potentials and aggregation behavior were investigated to determine potential mobility in soil materials. Furthermore, the adsorption of Pb2+ onto iron oxides and DOM was determined at pH 6 in three variants: (i) goethite colloids + Pb2+, (ii) DOM + Pb2+, and (iii) OMCG colloids + Pb2+. In the absence of DOM, the zeta potential of goethite colloids was positive. With rising DOC concentration, the zeta potential turned increasingly negative. The zeta potential affected goethite colloid aggregation behavior. While colloids repel each other both in the absence of DOM and at DOC concentrations above 1.0 mg/l, the more neutral zeta potential at 0.1 mg/l DOC caused aggregation of OMCG colloids. Furthermore, the adsorption of Pb2+ onto goethite colloids at different DOC concentrations is likewise related to zeta potentials. Only small amounts of Pb2+ were adsorbed on pure goethite surfaces in the absence of DOM. In contrast, Pb2+ was readily adsorbed onto OMCG colloids at 1.0 mg/l DOC. Notably, the largest amount of Pb2+ adsorption was found for pure DOM in the absence of goethite colloids. This can be explained by the fact that pure DOM has more potential sorption sites left for Pb2+ than DOM coatings on goethite colloids have. We conclude that DOM-induced changes in goethite colloid zeta potentials affected both the colloid aggregation behavior and the sorption capacity for Pb2+.These results serve as the base for transport experiments, in which the mobility of (i) Pb2+, (ii) Pb2+ + DOM, and (iii) Pb2+ + OMCG colloids will be determined in different soil materials ranging from HCl-cleaned quartz sand to goethite coated sand to undisturbed natural soil

    LP (a) levels and apo (a) phenotypes in urban black South African men

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    CITATION: Carstens, M. E., Burgess, L. J. & Taljaard, J. J. F. 1998. LP (a) levels and apo (a) phenotypes in urban black South African men. South African Medical Journal, 88:139-142.The original publication is available at http://www.samj.org.zaObjective. To investigate the lipoprotein (a) (Lp (a)) levels and apolipoprotein (a) (apo (a)) phenotypes in a group of urban black South African men. Design. Cross-sectional design. Setting. Lead acid battery plant, East London, Eastern Cape. Participants. Blood samples from a study on the association between lead and renal failure were kindly donated for the present study and 111 of the donors participated (K Steyn - personal communication). Outcome measures. Lp (a) levels and apo (a) phenotypes. Results. Three groups were identified: those with normal ( 700 U/l) plasma Lp (a) concentrations. Nine apo (a) phenotypes and 26 combinations thereof could be discerned. Apart from the single- and double-band phenotypes described before, triple-band phenotypes were also present. As the Lp (a) values increased, the relative frequency of the single-band phenotype decreased, whereas the relative frequency of the double-band phenotype increased. The relative frequency of the triple-band phenotype was highest in the group with high Lp (a) concentrations. No correlation was evident between the size of the apo (a) isoforms and the Lp (a) concentrations. Conclusions. Raised plasma Lp (a) levels have been associated with coronary heart disease (CHD). In addition, it has been proposed that the apo (a) gene determined plasma Lp (a) concentrations. These studies were performed using plasma from white subjects. CHD is uncommon in black South Africans. The reason may be that, given the lack of relationship between the size of the apo (a) isoforms and the Lp (a) concentrations observed in the present study, factors other than the isoform size may determine the Lp (a) levels in this particular ethnic group.Publisher’s versio

    Second Information Technology in Education Study: SITES 2006 Technical Report

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    SITES 2006 examined how teachers and students used ICT and the extent to which certain pedagogical practices considered to be conducive to the development of ""21st century"" skills were present in comparison to traditionally important ones. These 21st century skills were defined in terms of students' abilities to engage in lifelong learning (collaborative and self-directed inquiry) and their connectedness (ability to collaborate with and learn from peers and experts). In addition, analyses were conducted to identify conditions at the system, school, and teacher level that were associated with different pedagogical practices and different ways of using ICT for teaching and learning. The study used questionnaires to collect information from school principals, technology coordinators, and mathematics and science teachers; a national context questionnaire gathered policy information on education and ICT use. For 15 countries that participated in SITES Module 1, SITES 2006 also provided an opportunity to examine changes in pedagogy and ICT use since 1998. The main data collection took place in 2006. In 18 countries, the data were collected online

    LP (a) levels and apo (a) phenotypes in urban black South African men

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    Objective. To investigate the lipoprotein (a) (Lp (a)) levels and apolipoprotein (a) (apo (a)) phenotypes in a group of urban black South African men.Design. Cross-sectional design.Setting. Lead acid battery plant, East London, Eastern Cape.Participants. Blood samples from a study on the association between lead and renal failure were kindly donated for the present study and 111 of the donors participated (K Steyn - personal communication).Outcome measures. Lp (a) levels and apo (a) phenotypes.Results. Three groups were identified: those with normal (&lt;300 U/I), intermediate (300 - 700 U/I) and high (&gt; 700 U/I) plasma Lp (a) concentrations. Nine apo (a) phenotypes and 26 combinations thereof could be discerned. Apart from the single- and double-band phenotypes described before, triple-band phenotypes were also present. As the Lp (a) values increased, the relative frequency of the single-band phenotype decreased, whereas the relative frequency of the double-band phenotype increased. The relative frequency of the triple-band phenotype was highest in the group with high Lp (a) concentrations. No correlation was evident between the size of the apo (a) isoforms and the Lp (a) concentrations.Conclusions. Raised plasma Lp (a) levels have been associated with coronary heart disease (CHD). In addition, it has been proposed that the apo (a) gene determined plasma Lp (a) concentrations. These studies were performed using plasma from white subjects. CHD is uncommon in black South Africans. The reason may be that, given the lack of relationship between the size of the apo (a) isoforms and the Lp (a) concentrations observed in the present study, factors other than the isoform size may determine the Lp (a) levels in this particular ethnic group
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