Participation rates in physics 12 in BC: Science teachers’ and students’ views

Abstract

In recent years, participation rates in the British Columbia (BC) provincial physics exams have been low, compared with chemistry and biology. A qualitative study employing questionnaire and interview methods sought the views of teachers and students of senior science courses on why this is the case. Data analysis revealed that students’ decisions about Physics 12 were influenced by their perceptions of the mathematical content of physics, the physics teachers’ personalities and teaching styles, the perceived difficulty of physics, and prior experience of physics. We conclude that enhancing student interest in taking physics at advanced high school levels may necessitate a wider, more articulated exposure to topics in physics, together with more careful attention to mathematical background and skills.     

Use of a specific anti‐stretch mark cream for preventing or reducing the severity of striae gravidarum. Randomized,double‐blind,controlled trial

Few studies have tested the efficacy of commercially available cosmetic products for preventing striae gravidarum. Therefore, the objective of this study was to evaluate efficacy on prevention of striae gravidarum using a specific anti‐stretch mark cream containing hydroxyprolisilane‐C, rosehip oil, Centella asiatica triterpenes and vitamin E. A randomized, double‐blind, placebo‐controlled trial was conducted between November 2009 and April 2011. Pregnant women were included and classified as treated group (emollient and moisturizer containing hydroxyprolisilane C, rosehip oil, Centella asiatica triterpenes and vitamin E) and control group (cream without the active ingredients). Overall incidence of stretch marks during pregnancy was 33.3% for the control group and 37.6% for the treated group (n.s.). Severity of previous stretch marks significantly increased in the control group during the study (17.8%, P = 0.001), but not in the treated group (6.3%, ns). In women who developed new stretch marks during the study, there was a significantly greater ‘difference in severity’ (between baseline and maximum severity) in control group vs. treated group (0.47 [0.57] vs. 0.14 [0.60], P = 0.031). In women without previous striae, incidence of these marks was significantly lower for the treated group patients compared with control group (5.6% vs. 35%, P = 0.031, OR: 9.2 [95% CI: 1.0–83.3]). The use of the anti‐stretch mark product is proved to be effective in reducing severity of the striae during pregnancy, prevents the appearance of new striae and halts progression of those already present. In women who had no striae at baseline, use of the anti‐stretch mark cream was more effective than placebo in preventing new stretch marks.     

Parathyroid detection in secondary hyperparathyroidism with 123I/99mTc-sestamibi subtraction single photon emission computed tomography

123I/99mTc-sestamibi subtraction single photon emission computed tomography (SPECT) has been proposed to detect hyperplastic parathyroid tissue, but the clinical usefulness of this technique in secondary hyperparathyroidism is uncertain. The purpose of this study was to evaluate preoperative parathyroid localization using 123I/99mTc-sestamibi subtraction SPECT in patients with renal failure and secondary hyperparathyroidism. Nineteen patients with chronic renal failure and secondary hyperparathyroidism underwent 123I/99mTc-sestamibi subtraction SPECT imaging preoperatively. None of these patients had undergone previous neck surgery. The location, weight, and histopathological results of all identified parathyroid glands were recorded. Surgery was considered successful in all patients, with resection of a total of 74 hyperplastic parathyroid glands. 123I/99mTc-sestamibi subtraction SPECT correctly identified 57 of these parathyroid glands (77% sensitivity). The mean weight among the true positive glands (n = 57) was 1031 mg (range, 45-7900 mg), and that among the false negative glands (n = 17) was 465 mg (range, 20-1800 mg). This difference between the mean weights was statistically significant (P = 0.018). There was a positive correlation between parathyroid weight and detectability with 123I/99mTc-sestamibi subtraction SPECT (Spearman correlation = 0.28; P = 0.0167). 123I/99mTc-sestamibi subtraction SPECT is able to correctly localize hyperplastic parathyroid glands in patients with renal failure and secondary hyperparathyroidism, but there is a fairly weak relationship between preoperative detection rate and anatomical parathyroid gland size.     

Characterisation of technologically proficient wild Lactococcus lactis strains resistant to phage infection

The aim of this work was to establish whether Lactococcus lactis strains isolated from spontaneous dairy fermentations exhibited useful milk-processing capabilities and resistance to bacteriophage infection in order to be used as components in starter formulations. The 33 out of 100 isolates of L. lactis, originated from farmhouse cheeses, were found to be resistant to a collection of 34 phages belonging to the c2 and 936 groups. Six of the isolates were discarded as potential starters because they were lysogenic and other five because they produced tyramine. Plasmid and chromosomal profiles of the 22 remaining isolates allowed their classification into 16 different strains. All of these were good lactic acid producers from lactose, moderately proteolytic and, in eight cases, diacetyl production from citrate was observed. The mechanism(s) leading to the phenotype of phage resistance was identified for all the strains used in this study. Inhibition of adsorption was the most frequent one, although genetic determinants for some abortive infection systems were also detected (abiB, abiG and abiI). Frequently, more than one mechanism was present in the same strain. One of the strains, L. lactis IPLA542, was selected as a model starter for pilot fermentations. It clotted milk normally both in the absence and in the presence of phage at concentrations that completely abolished the process when promoted by a phage-susceptible strain.     

The effect of professor ethnicity and gender on student evaluations: Judged before met.

Ethnic minority academicians face a number of challenges in the “ivory tower.” One set of challenges arises from the racial stereotypes that others hold, and the current research investigates the stereotypes held by students before they even meet such professors. After providing college preparatory students with a CV of a professor (differing in their race—White, Black, or Asian; their gender—male or female; and their academic discipline—Science or Humanities), students evaluated the professor on measures of competence, legitimacy, and interpersonal skills. We found that students evaluated Black professors to be significantly less competent and legitimate than their White and Asian counterparts. Both Black and Asian professors were judged to have significantly less interpersonal skills than White professors. No gender main effects emerged. Professors in science were judged to be more competent and legitimate than professors in humanities. Very few interactions surfaced. We discuss our results in terms of previous stereotype research and the implications our results have for further compounding the challenges that Black professors face in academia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Production of leather‐like composites using chemically modified short leather fibers. I: Chemical modification by emulsion polymerization

In order to evaluate the possible use of short leather fibers to produce leather‐like composites, five kilograms of fibers (extracted from leather wastes) were modified by in situ emulsion polymerization of methyl methacrylate (MMA). This treatment was performed in order to increase the compatibility of leather fibers with several commodity polymers used in the shoe and furrier industries. The chemical modification was carried out by aqueous emulsion polymerization initiated by a redox system (potassium persulfate and sodium metabisulfite). The effects of the monomer and redox initiator content as well as the reaction temperature were evaluated. The modified short leather fibers were characterized by instrumental techniques such as Infrared Spectroscopy (IR), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), X‐ray Diffraction and Scanning Electronic Microscopy (SEM). The results show that the polymer is formed on the exterior of fibers (deposited fraction) as well as in the interior (by grafting or forming interpenetrated networks). The treatment significantly improves the thermal stability of fibers. It also reduces their water adsorption capacity, as a coating of PMMA is produced over the leather surface, as microscopic analysis has revealed. The last characteristic could be an advantage in certain applications.     

Interpreting Teachers' Perceptions of Contextual Influences on Sexuality Discourses Within the School Curriculum: Lessons From Sex Health Education Teachers in Kampala,Uganda

Analysis of key findings of a study that investigated six Ugandan teachers' perceptions of contextual influences on sexuality discourses revealed that though there is some form of sex education in schools and though teachers are very enthusiastic about its implementation, it is largely constrained by conflicting social stances held by various stakeholders and needs reform. A nuanced approach to understanding practical realities and complexities involved in designing an effective sex education framework is discussed. These findings have critical implications on the strategies and the nature of sex health curricular discourses that teachers develop and implement in culturally diverse classrooms beyond Uganda.     

Degradability of extruded polyethylene/chitosan blends compatibilized with polyethylene‐graft‐maleic anhydride under natural weathering

The impact of chitosan on the natural weathering behavior of two blends obtained by mixing either polyethylene (PE) with chitosan or PE, chitosan and polyethylene‐graft‐maleic anhydride (PEgMA) as a compatibilizer is analyzed. In order to follow the weathering behavior of both the uncompatibilized and compatibilized systems, the blend films are exposed to outdoor conditions for 6 months. The weathering behavior of the films is monitored by mechanical tests, spectroscopic Fourier transform infrared, and morphological analyses at different weathering periods of time. The presence of chitosan in the blends accelerates significantly the degradation of the films. Apparently, PEgMA also accelerates the photo‐oxidation rate of the films. This behavior appears to be related to the photo‐oxidative instability of maleic anhydride, and also to the better dispersion of chitosan in the PE matrix, which is due to the interactions in the PE/chitosan interface caused by the addition of the compatibilizer. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41045.     

Influence of surface treatments on the physicochemical properties of short sisal fibers: Ethylene vinyl acetate composites

Natural fibers (NFs) are rich in cellulose and also they are a low cost, easily renewable source for polymer composites. However, the presence of impurities (waxes, lignin, etc.) and hydroxyl groups produce those NFs with less ability to reinforce polymeric matrices. Short sisal fibers (SSF) were subjected to three different chemical treatments (alkaline, dicumyl peroxide, and silane). Composites of ethylene vinyl acetate (EVA) and chemically modified SSF were prepared by mechanical mixing at the melt state of the polymer matrix (130°C) using a two roll mill. The influences of fiber content and chemical treatment on the mechanical properties of the composites were evaluated. The tensile strength increased for every such treated SSF‐reinforced composite. There was also a noticeable increase in elastic modulus compared with the unfilled matrix. The elongation at break values decreased as the fiber content was increased. Moreover, it was observed that the surface treatment of the SSF improved the fiber dispersion within the EVA matrix. The thermal stability of SSF was analyzed by thermogravimetic analysis. Potentially, the recyclability of the composites might be promising due to the lower specific gravity of NF, accompanied by low cost, and with the added advantage of biodegradability. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers