Research on Reform in Mathematics Education, 1993-2000

Proponents and opponents of reform of mathematics education all cite the research base in support of their positions. This article reports the results of a review of studies that contained empirical evidence of the effects of reform or the difficulty of implementing reform that were published between 1993 and 2000. The studies reviewed indicate that implementation of math reform contributes to student achievement, but evidence abounds of superficial implementation and barriers to enactment. There are well-documented strategies for reducing these barriers, the most promising strategies being inservice that simultaneously focuses on teachers' practice and their cognition about mathematics teaching.Promoteurs et adversaires d'une réforme en enseignement des mathématiques puisent tous dans la recherche pour appuyer leurs points de vue. Cet article présente le résultat d'une analyse d'études empiriques publiées entre 1993 et 2000 et qui évoquent les effets d'une réforme ou la difficulté d'en mettre une en application. Selon les études analysées, la mise en œuvre d'une réforme en enseignement des mathématiques contribue aux réalisations des élèves. Toutefois, énormément d'articles évoquent une mise en œuvre superficielle et des obstacles à la réforme. Parmi les stratégies bien documentées pour minimiser ces obstacles, celles qui promettent le plus impliquent une formation pour enseignants en cours d'emploi qui touche à la fois les méthodes des enseignants et leurs connaissances sur l'enseignement des mathématiques

Treatment of thyrotoxicosis with iodine-125: A clinical and laboratory study

This study is primarily a clinical assessment of a new radioisotope of iodine (iodine-125) for the treatment of thyrotoxicosis. The thesis consists of three sections, B and C. The first Chapter of Section A is concerned with the currently used treatments for thyrotoxicosis (Graves' disease), special attention being given, to iodine-131. There is no excuse for the proportion of the Chapter which deals with the poor results, side effects and complications of the therapies, and again prominence is given to iodine-131 in particular the problem of post therapy hypothyroidism. Included in this Chapter is a personally analysed combined radiotherapeutic trial using iodine-131 and carbimazole. The rationale for the use of iodine-125 is detailed in Section A Chapter II. The rich spectrum of low energy short range electrons emitted from iodine-125 preferentially irradiates the hormone producing region at the apox of the follicular cells without killing the cells. It is theoretically possible using iodine-125 to produce rapid control of the disease without causing post-treatment hypothyroidism. Animal experiments carried out by other investigators confirming this hypothesis are described. Section B consists of three Chapters which deal with the clinical trials of iodine-125 in patients. In Chapter I the excellent results of large therapy doses justified this approach and encouraged extension f the trials using smaller but empirioal doses. The method of calculating the rad dose at different levels of the follicular cell is described. The main clinical trial, the treatment of 265 thyrotoxic patients with different dose schedules of iodine-125, is detailed in Chapter II. The outcome is related to the sex and age of the patients, the total dose prescribed, the thyroid size before therapy, the dose of iodine-125 prescribed per gram of thyroid and the length of follow up. Clinical trials of iodine-125 in three centres are discussed and the overall pattern of results integrated. Complications which have arisen after iodine-125 treatment are included in Chapter III as are prospective investigations into potential hazards. Two Chapters in Section C deal with the radiobiological differences in the thyrotoxic thyroid after treatment with iodine-125 compared with iodine-131. In the first Chapter, routine radioiodine tests, an intravenous perchlorate discharge test, radiochromatograms of serum and combined use of serum thyroxine, T3 resin and T.S.H. assay are utilised. In the second mathematical techniques awe employed

Hosting and Human Rights: The Summer Olympics in the Twenty-First Century

During the twenty-first century, Summer Olympic Games have been used to distract from, justify and push through acts of increased securitization, surveillance, and displacement of the host city populace. Situating sport within the field of International Relations, we outline these civil and human rights intrusions across successive Games. From Sydney 2000 to Rio de Janeiro 2016, we explicate the consequences, contestedness, and evolution of repressive techniques applied at each Games using theories of hegemony espoused by Antonio Gramsci, Robert W. Cox, and Raymond Williams, among others. In doing so, we demonstrate how the International Olympic Committee (IOC), their partners and host cities are wedded in a symbolic and symbiotic courtship that manufactures local consent for and normalizes human right infringements; simultaneously providing the architecture for the spread and imposition of neoliberal order on the citizenry, while masking the damage done by and through the Olympics. Finally, we close by asserting that the current formulation of the Olympics are not ‘the best we can do.' Instead, through the counterhegemonic potential of critical approaches and engaged, strategic action, a transformation of critical consciousness - and the Olympics, into something to be proud of - remain a live and entirely possible option

The New International Health Regulations and the Federalism Dilemma

The recent revision of the International Health Regulations, say Wilson and colleagues, is both long overdue and eminently necessary to face the challenges of an increasingly globalized world

Laboratory observations of double-diffusive convection using high-frequency broadband acoustics

Author Posting. © The Author(s), 2008. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Experiments in Fluids 46 (2009): 355-364, doi:10.1007/s00348-008-0570-9.High-frequency broadband (200-300 kHz) acoustic scattering techniques have been used to observe the diffusive regime of double-diffusive convection in the laboratory. Pulse compression signal processing techniques allow 1) centimetre-scale interface thickness to be rapidly, remotely, and continuously measured, 2) the evolution, and ultimate merging, of multiple interfaces to be observed at high-resolution, and 3) convection cells within the surrounding mixed layers to be observed. The acoustically measured interface thickness, combined with knowledge of the slowly-varying temperatures within the surrounding layers, in turn allows the direct estimation of double-diffusive heat and buoyancy fluxes. The acoustically derived interface thickness, interfacial fluxes and migration rates are shown to support established theory. Acoustic techniques complement traditional laboratory sampling methods and provide enhanced capabilities for observing the diffusive regime of double-diffusion in the ocean.Funding for this project was provided by the Ocean Acoustics program at the Office of Naval Research, and by the WHOI Cecil and Ida Greene Technology Award

Potato tuber pectin structure is influenced by pectin methyl esterase activity and impacts on cooked potato texture

Although cooked potato tuber texture is an important trait that influences consumer preference, a detailed understanding of tuber textural properties at the molecular level is lacking. Previous work has identified tuber pectin methyl esterase activity (PME) as a potential factor impacting on textural properties. In this study, tuber PME isoform and gene expression profiles have been determined in potato germplasm with differing textural properties as assessed using an amended wedge fracture method and a sloughing assay, revealing major differences between the potato types. Differences in pectin structure between potato types with different textural properties were revealed using monoclonal antibodies specific for different pectic epitopes. Chemical analysis of tuber pectin clearly demonstrated that, in tubers containing a higher level of total PME activity, there was a reduced degree of methylation of cell wall pectin and consistently higher peak force and work done values during the fracture of cooked tuber samples, demonstrating the link between PME activity, the degree of methylation of cell wall pectin, and cooked tuber textural properties

Spatially heterogeneous argon-isotope systematics and apparent ⁴⁰Ar/³⁹Ar ages in perlitised obsidian

In situ laser ablation Ar-isotope analyses of variably hydrated and devitrified obsidian from the ~ 27 Ma Cochetopa Dome, San Juan, USA, reveal complex interplay between degassing of initial Ar and absorption of atmospheric Ar. These processes have locally modified the Ar-isotope composition of the obsidian and led to spurious, spatially-heterogeneous Ar-isotope and 40Ar/39Ar age data. Small perlite beads exhibit older apparent Ar-ages at the rims than the cores. This is interpreted as an apparent excess of 40Ar at the rims, produced either by a) diffusion of excess 40Ar into the bead during flushing of the lava with excess 40Ar-bearing volcanic gas, or by b) isotopic fractionation during degassing of initial Ar, causing preferential loss of 36Ar over 40Ar at the bead rims. The second interpretation is favoured by a relative enrichment of 36Ar in the core of a perlite bead along a microlite-free (poorly degassed) flow band, and by a lack of age variation in a larger, fresh, well-degassed perlite bead. These isotopic gradients were later overprinted during glass hydration by absorption of Ar with near-atmospheric composition, resulting in elevated 36Ar and reduced radiogenic 40Ar* yields at the rims of perlite beads. These complex interactions essentially represent the mixing of three distinct Ar reservoirs: initial trapped Ar that may or may not be fractionated, an isotopically atmospheric Ar component introduced during hydration, and radiogenic 40Ar*. Such reservoir mixing is the underlying reason for poor correlations on isotope correlation diagrams and the difficulties in validating the composition of the non-radiogenic Ar component. We thus suggest that high 36Ar yields are a combination of the incomplete degassing of initial (possibly magmatic) Ar and the gain of Ar during interaction between the obsidian and meteoric/atmospheric fluids. Our analyses emphasise the challenging nature of 40Ar/39Ar dating obsidian samples, but also point to possible solutions by careful sample characterisation and selection of highly degassed samples

777-786

Abstract. The cytotoxic effects of strawberry polyphenols were investigated on normal cells and tumour cells derived from the same patient. A human prostate epithelial cell line (P21) and two tumour cell lines (P21 tumour cell line 1 and 2) derived from the same patient, and a normal human breast epithelial cell line (B42) and a tumour line derived from it (B42 clone 16) were used. A polyphenol-rich extract derived from strawberry or anthocyanin or tannin-rich sub-fractions were applied to the cell lines in doses varying from 50 to 1.5 μg/ml. The strawberry extract was cytotoxic with doses of ~5 μg/ml causing a 50% reduction in cell survival in both the normal and the tumour lines. The extracts were also cytotoxic to peripheral blood human lymphocytes stimulated with phytohaemagglutinin but higher levels (>20 μg/ml for 50% reduction in cell survival) were required. After fractionation of the strawberry sample, the cytotoxicity was retained in the tannin-rich fraction and this fraction was considerably more toxic to all cells (normal or tumour cell lines or lymphocytes) than the anthocyanin-rich fraction. Established prostate (LNCaP and PC-3) and breast (MCF-7) tumour cell lines were more resistant to the strawberry extract with concentrations of 50 μg/ml required for 50% reduction in cell survival, which is similar to levels in previous studies on the antiproliferative effects of berry extracts. Although these concentrations are much greater than possible physiological levels, they are comparable to those reported in other studies. From these findings, we conclude that there is little evidence to assume that polyphenols from strawberry have a differential cytotoxic effect on tumour cells relative to comparable normal cells from the same tissue derived from the same patient