Annual National Assessment (ANA) performance in Mathematics across the primary grades in South Africa indicates a decrease in mean performance across Grades 1-6. In this paper, we explore the ...apparently high performance in Grade 1 through a comparative investigation of learner responses on two assessments: the Grade 1 ANA taken in February 2011 by Grade 2 learners and a diagnostic oral interview test drawn from the work of Wright et al. (2006), administered at the same time. Our findings point to a predominant pattern of high performance on the ANA and low performance on Wright et al.'s tests. In-depth analysis of the responses of two learners in this group indicates that this discrepancy is due to acceptance in the ANA of correct answers produced through highly rudimentary counting strategies. The diagnostic test, in contrast, awards lower marks when correct answers are produced in inefficient ways. We conclude with concerns that acceptance of low-level counting strategies in the ANA may well work against persuading Grade 1 and 2 teachers to work towards more sophisticated strategies.
This paper examines the conceptions of 'number sense' as promoted in pre-service primary mathematics education courses at 11 South African Higher Education Institutions through the texts used by ...academics or prescribed for students. While all the participating institutions agree that the development of primary school learners' 'number sense' is central to their mathematics methodology courses and that there is an overwhelming amount of research and literature on 'number sense' nationally and internationally, their conceptualisations of the nature of 'number sense' vary. Teacher educators, who develop pre-service teacher education courses, were asked to provide the texts, used to underpin the 11 universities' mathematics education modules in the Bachelor of Education (Foundation and Intermediate Phases) and Post Graduate Certificate in Education (Foundation and Intermediate Phases) programmes. These texts were analysed drawing on Whitacre et al.'s emphasis on three 'number sense constructs' identified as Innate Number Sense, Early Number Sense and Mature Number Sense. The results show that there is no common language of description for 'number sense' across the 11 universities. This research implies that there is a need to develop a consistent understanding of 'number sense' and how it is developed across institutions.
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Research on mathematical equivalence, and to some extent, on number structure in early grade mathematics, has shown that most students at primary and secondary levels understand these concepts ...instrumentally rather than relationally. The study reported in this paper uses a design research approach to explore both mathematical equivalence and number structure in a primary pre-service teacher education programme at a university in South Africa and reports on an intervention strategy intended to culminate in developing design principles comprising guidelines for the effective teaching of number structure and mathematics equivalence in primary pre-service teacher education programmes. The mixed method study comprises 70 first-year primary pre-service teachers (PSTs) and a teacher educator. The PSTs wrote pre- and post-tests, and were interviewed following the pre-test. Skemp's notion of relational and instrumental understanding guided the design of the intervention and the analysis of the data. The results from the study indicates that PSTs' understanding of the notion of equivalence is similar to what has been reported for students in schools, and that there were some learning gains in the post-test results. Based on the findings from the study in general, some emergent design principles are proposed.
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Annual National Assessment (ANA) performance in Mathematics across the primary grades in South Africa indicates a decrease in mean performance across Grades 1–6. In this paper, we explore the ...apparently high performance in Grade 1 through a comparative investigation of learner responses on two assessments: the Grade 1 ANA taken in February 2011 by Grade 2 learners and a diagnostic oral interview test drawn from the work of Wright et al. (2006), administered at the same time. Our findings point to a predominant pattern of high performance on the ANA and low performance on Wright et al.’s tests. In-depth analysis of the responses of two learners in this group indicates that this discrepancy is due to acceptance in the ANA of correct answers produced through highly rudimentary counting strategies. The diagnostic test, in contrast, awards lower marks when correct answers are produced in inefficient ways. We conclude with concerns that acceptance of low-level counting strategies in the ANA may well work against persuading Grade 1 and 2 teachers to work towards more sophisticated strategies.
A Research Report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements of the degree of Master of Science. October 2012, ...Johannesburg.
Several commentators describe the low performance of South African students in mathematics as ‗a crisis‘. In the Foundation Phase specifically, there is evidence of a lack of shift from concrete counting-based strategies to more abstract calculation-based strategies (Ensor et al., 2009; Schollar, 2009). Concrete counting-based strategies refer to actions where the learner cannot find the answer to a mathematical problem without using concrete objects. In contrast, abstract calculation-based strategies involve strategies where the child does not need concrete objects to find the answer, but can instead use mental calculations in which numbers have been transformed into abstract objects upon which operations can then be carried out. Ensor et al argue that the poor mathematical results in South Africa are the result of inefficient moves made by learners from counting to calculating. In their study, many students failed to move their thinking sufficiently forward from concrete counting actions to abstract thinking.;
The focus of this study is to investigate a sample of Grade 2 learners‘ strategies on tasks drawn from the Learning Framework in Number (LFIN) test and responses on number related questions in the Annual National Assessment tests (ANA). I use the Learning Framework in Number to describe the stage of learners in their shift from concrete to a more abstract way of thinking about number. The theory of reification refers to the turning of processes into objects, and in this research, the origin of an abstract object in reification is explored. I also aim to understand the kinds of information I can get from children‘s grasp of early number strategies, by looking at the responses of learners on the ANA and LFIN tests. My research question is: What do the two tests (ANA and LFIN) tell us about the strategies on early number used by a sample of Grade 2 learners in a township school in Gauteng? The two critical questions that follow from this are:;
How does learner performance on number problems compare across the two tests?;
What evidence in relation to concrete/abstract strategies is evident in the responses of learners in the two tests?;
My findings showed that the learners in the school that I investigated still relied a great deal on concrete counting methods to answer questions. In spite of this, the mean ANA mark were much higher than the LFIN mean. The low number range of the ANA test, (1-34 for most of the number related questions), made it possible for the learners to use concrete counting (fingers or tallies) to answer the questions. The relatively low LFIN mark range indicated that children had difficulties in moving to more abstract ways of working with number. The implications of the reliance on concrete counting is potential difficulties when the learners move into higher grades where the number range is much higher, making the use of concrete methods time consuming and error prone.
In this study involving nearly 3400 patients with venous thromboembolism, both prophylactic and therapeutic doses of rivaroxaban were superior to aspirin in reducing the risk of recurrent ...thromboembolism with a similar risk of bleeding.
Venous thromboembolism, which includes deep-vein thrombosis and pulmonary embolism, is the third most common cause of vascular death after myocardial infarction and stroke.
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The mainstay of treatment is anticoagulation,
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and in patients without active cancer, guidelines suggest the use of direct oral anticoagulant agents such as rivaroxaban over vitamin K antagonists such as warfarin.
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Anticoagulation therapy is administered for 3 months or longer, depending on the balance between the risk of recurrent venous thromboembolism and the risk of bleeding.
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In patients without reversible risk factors, the risk of recurrent venous thromboembolism is as much as 10% in the first . . .
IMPORTANCE: The efficacy of factor XIa inhibition for thromboprophylaxis is unknown. Osocimab is a long-acting, fully human monoclonal antibody that inhibits factor XIa. OBJECTIVE: To compare ...different doses of osocimab with enoxaparin and apixaban for thromboprophylaxis in patients who have undergone knee arthroplasty. DESIGN, SETTING, AND PARTICIPANTS: Randomized, open-label, adjudicator-blinded, phase 2 noninferiority trial with observer blinding for osocimab doses, conducted at 54 hospitals in 13 countries. Adult patients undergoing unilateral knee arthroplasty were randomized from October 2017 through August 2018 and followed up until January 2019. INTERVENTIONS: Single intravenous osocimab postoperative doses of 0.3 mg/kg (n = 107), 0.6 mg/kg (n = 65), 1.2 mg/kg (n = 108), or 1.8 mg/kg (n = 106); preoperative doses of 0.3 mg/kg (n = 109) or 1.8 mg/kg (n = 108); or 40 mg of subcutaneous enoxaparin once daily (n = 105) or 2.5 mg of oral apixaban twice daily (n = 105) for at least 10 days or until venography. MAIN OUTCOMES AND MEASURES: The primary outcome was venous thromboembolism incidence between 10 and 13 days postoperatively (assessed by mandatory bilateral venography performed 10 to 13 days after surgery or confirmed symptomatic deep vein thrombosis or pulmonary embolism). A 5% noninferiority margin compared with enoxaparin was chosen. The primary safety outcome of major or clinically relevant nonmajor bleeding was assessed until 10 to 13 days postoperatively. RESULTS: Of 813 randomized participants (mean SD age, 66.5 years 8.2 years; body mass index, 32.7 5.7; and 74.2% women), 600 were included in the per-protocol population used for the primary analysis. The primary outcome occurred in 18 patients (23.7%) receiving 0.3 mg/kg, 8 (15.7%) receiving 0.6 mg/kg, 13 (16.5%) receiving 1.2 mg/kg, and 14 (17.9%) receiving 1.8 mg/kg of osocimab postoperatively; 23 (29.9%) receiving 0.3 mg/kg and 9 (11.3%) receiving 1.8 mg/kg of osocimab preoperatively; 20 (26.3%) receiving enoxaparin; and 12 (14.5%) receiving apixaban. Osocimab given postoperatively met criteria for noninferiority compared with enoxaparin with risk differences (1-sided 95% CIs) of 10.6% (95% CI, –1.2% to ∞) at the 0.6-mg/kg dose; 9.9% (95% CI, –0.9% to ∞) at the 1.2-mg/kg dose, and 8.4% (95% CI, –2.6 to ∞) at the 1.8-mg/kg dose. The preoperative dose of 1.8 mg/kg of osocimab met criteria for superiority compared with enoxaparin with a risk difference of 15.1%; 2-sided 90% CI, 4.9% to 25.2%). Postoperative and preoperative doses of 0.3 mg/kg of osocimab did not meet the prespecified criteria for noninferiority, with risk differences (1-sided 95% CIs) of 2.6% (95% CI, –8.9% to ∞) and –3.6% (95% CI, –15.5% to ∞), respectively. Major or clinically relevant nonmajor bleeding was observed in up to 4.7% of those receiving osocimab, 5.9% receiving enoxaparin, and 2% receiving apixaban. CONCLUSIONS AND RELEVANCE: Among patients undergoing knee arthroplasty, postoperative osocimab 0.6 mg/kg, 1.2 mg/kg, and 1.8 mg/kg met criteria for noninferiority compared with enoxaparin, and the preoperative 1.8-mg/kg dose of osocimab met criteria for superiority compared with enoxaparin for the primary outcome of incidence of venous thromboembolism at 10 to 13 days postoperatively. Further studies are needed to establish efficacy and safety of osocimab relative to standard thromboprophylaxis. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03276143
Circadian rhythms in mammals are generated by a feedback loop in which the three PERIOD (PER) proteins, acting in a large complex, inhibit the transcriptional activity of the CLOCK-BMAL1 dimer, which ...represses their own expression. Although fundamental, the mechanism of negative feedback in the mammalian clock, or any eukaryotic clock, is unknown. We analyzed protein constituents of PER complexes purified from mouse tissues and identified PSF (polypyrimidine tract—binding protein—associated splicing factor). Our analysis indicates that PSF within the PER complex recruits SIN3A, a scaffold for assembly of transcriptional inhibitory complexes and that the PER complex thereby rhythmically delivers histone deacetylases to the Per1 promoter, which repress Per1 transcription. These findings provide a function for the PER complex and a molecular mechanism for circadian clock negative feedback.
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Eukaryotic circadian clocks are built on transcriptional feedback loops. In mammals, the PERIOD (PER) and CRYPTOCHROME (CRY) proteins accumulate, form a large nuclear complex (PER complex), and ...repress their own transcription. We found that mouse PER complexes included RNA helicases DDX5 and DHX9, active RNA polymerase II large subunit, Per and Cry pre-mRNAs, and SETX, a helicase that promotes transcriptional termination. During circadian negative feedback, RNA polymerase II accumulated near termination sites on Per and Cry genes but not on control genes. Recruitment of PER complexes to the elongating polymerase at Per and Cry termination sites inhibited SETX action, impeding RNA polymerase II release and thereby repressing transcriptional reinitiation. Circadian clock negative feedback thus includes direct control of transcriptional termination.
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This chapter describes the pharmacology of approved parenteral anticoagulants, including the indirect anticoagulants, unfractionated heparin (UFH), low-molecular-weight heparins (LMWHs), ...fondaparinux, and danaparoid as well as the direct thrombin inhibitors hirudin, bivalirudin, and argatroban. UFH is a heterogeneous mixture of glycosaminoglycans that bind to antithrombin via a unique pentasaccharide sequence and catalyze the inactivation of thrombin factor Xa and other clotting factors. Heparin also binds to cells and other plasma proteins, endowing it with unpredictable pharmacokinetic and pharmacodynamic properties, and can lead to nonhemorrhagic side effects, such as heparin-induced thrombocytopenia (HIT) and osteoporosis. LMWHs have greater inhibitory activity against factor Xa than thrombin and exhibit less binding to cells and proteins than heparin. Consequently, LMWH preparations have more predictable pharmacokinetic and pharmacodynamic properties, have a longer half-life than heparin, and have a lower risk of nonhemorrhagic side effects. LMWHs can be administered once or twice daily by subcutaneous injection, without anticoagulant monitoring. Based on their greater convenience, LMWHs have replaced UFH for many clinical indications. Fondaparinux, a synthetic pentasaccharide, catalyzes the inhibition of factor Xa, but not thrombin, in an antithrombin-dependent fashion. Fondaparinux binds only to antithrombin; therefore, HIT and osteoporosis are unlikely to occur. Fondaparinux has excellent bioavailability when administered subcutaneously, has a longer half-life than LMWHs, and is given once daily by subcutaneous injection in fixed doses, without anticoagulant monitoring. Three parenteral direct thrombin inhibitors and danaparoid are approved as alternatives to heparin in HIT patients.
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