652 research outputs found

    Trends in Weekly Reported Net use by Children During and after Rainy Season in Central Tanzania.

    Get PDF
    The use of long-lasting insecticidal nets (LLINs) is one of the principal interventions to prevent malaria in young children, reducing episodes of malaria by 50% and child deaths by one fifth. Prioritizing young children for net use is important to achieve mortality reductions, particularly during transmission seasons. Households were followed up weekly from January through June 2009 to track net use among children under seven under as well as caretakers. Net use rates for children and caretakers in net-owning households were calculated by dividing the number of person-weeks of net use by the number of person-weeks of follow-up. Use was stratified by age of the child or caretaker status. Determinants of ownership and of use were assessed using multivariate models. Overall, 60.1% of the households reported owning a bed net at least once during the study period. Among net owners, use rates remained high during and after the rainy season. Rates of use per person-week decreased as the age of the child rose from 0 to six years old; at ages 0-23 months and 24-35 months use rates per person-week were 0.93 and 0.92 respectively during the study period, while for children ages 3 and 4 use rates per person-week were 0.86 and 0.80. For children ages 5-6 person-week ratios dropped to 0.55. This represents an incidence rate ratio of 1.67 for children ages 0-23 months compared to children aged 5-6. Caretakers had use rates similar to those of children age 0-35 months. Having fewer children under age seven in the household also appeared to positively impact net use rates for individual children. In this area of Tanzania, net use is very high among net-owning households, with no variability either at the beginning or end of the rainy season high transmission period. The youngest children are prioritized for sleeping under the net and caretakers also have high rates of use. Given the high use rates, increasing the number of nets available in the household is likely to boost use rates by older children

    The effect of seasoning with herbs on the nutritional, safety and sensory properties of reduced-sodium fermented Cobrançosa cv. table olives

    Get PDF
    This study aimed at evaluating the effectiveness of seasoning Cobrancosa table olives in a brine with aromatic ingredients, in order to mask the bitter taste given by KCl when added to reduced-sodium fermentation brines. Olives were fermented in two different salt combinations: Brine A, containing 8% NaCl and, Brine B, a reduced-sodium brine, containing 4% NaCl + 4% KCl. After the fermentation the olives were immersed in seasoning brines with NaCl (2%) and the aromatic herbs (thyme, oregano and calamintha), garlic and lemon. At the end of the fermentation and two weeks after seasoning, the physicochemical, nutritional, organoleptic, and microbiological parameters, were determined. The olives fermented in the reduced-sodium brines had half the sodium concentration, higher potassium and calcium content, a lower caloric level, but were considered, by a sensorial panel, more bitter than olives fermented in NaCl brine. Seasoned table olives, previously fermented in Brine A and Brine B, had no significant differences in the amounts of protein (1.23% or 1.11%), carbohydrates (1.0% or 0.66%), fat (20.0% or 20.5%) and dietary fiber (3.4% or 3.6%). Regarding mineral contents, the sodium-reduced fermented olives, presented one third of sodium, seven times more potassium and three times more calcium than the traditional olives fermented in 8% NaCl. Additionally, according to the panelists' evaluation, seasoning the olives fermented in 4% NaCl + 4% KCl, resulted in a decrease in bitterness and an improvement in the overall evaluation and flavor. Escherichia coli and Salmonella were not found in the olives produced.info:eu-repo/semantics/publishedVersio

    Glyoxal yield from isoprene oxidation and relation to formaldehyde: chemical mechanism, constraints from SENEX aircraft observations, and interpretation of OMI satellite data

    Get PDF
    Glyoxal (CHOCHO) is produced in the atmosphere by the oxidation of volatile organic compounds (VOCs). Like formaldehyde (HCHO), another VOC oxidation product, it is measurable from space by solar backscatter. Isoprene emitted by vegetation is the dominant source of CHOCHO and HCHO in most of the world. We use aircraft observations of CHOCHO and HCHO from the SENEX campaign over the southeast US in summer 2013 to better understand the CHOCHO time-dependent yield from isoprene oxidation, its dependence on nitrogen oxides (NOx  ≡  NO + NO2), the behavior of the CHOCHO–HCHO relationship, the quality of OMI CHOCHO satellite observations, and the implications for using CHOCHO observations from space as constraints on isoprene emissions. We simulate the SENEX and OMI observations with the Goddard Earth Observing System chemical transport model (GEOS-Chem) featuring a new chemical mechanism for CHOCHO formation from isoprene. The mechanism includes prompt CHOCHO formation under low-NOx conditions following the isomerization of the isoprene peroxy radical (ISOPO2). The SENEX observations provide support for this prompt CHOCHO formation pathway, and are generally consistent with the GEOS-Chem mechanism. Boundary layer CHOCHO and HCHO are strongly correlated in the observations and the model, with some departure under low-NOx conditions due to prompt CHOCHO formation. SENEX vertical profiles indicate a free-tropospheric CHOCHO background that is absent from the model. The OMI CHOCHO data provide some support for this free-tropospheric background and show southeast US enhancements consistent with the isoprene source but a factor of 2 too low. Part of this OMI bias is due to excessive surface reflectivities assumed in the retrieval. The OMI CHOCHO and HCHO seasonal data over the southeast US are tightly correlated and provide redundant proxies of isoprene emissions. Higher temporal resolution in future geostationary satellite observations may enable detection of the prompt CHOCHO production under low-NOx conditions apparent in the SENEX data

    Microscopic optical buffering in a harmonic potential

    Get PDF
    In the early days of quantum mechanics, Schrödinger noticed that oscillations of a wave packet in a one-dimensional harmonic potential well are periodic and, in contrast to those in anharmonic potential wells, do not experience distortion over time. This original idea did not find applications up to now since an exact one-dimensional harmonic resonator does not exist in nature and has not been created artificially. However, an optical pulse propagating in a bottle microresonator (a dielectric cylinder with a nanoscale-high bump of the effective radius) can exactly imitate a quantum wave packet in the harmonic potential. Here, we propose a tuneable microresonator that can trap an optical pulse completely, hold it as long as the material losses permit, and release it without distortion. This result suggests the solution of the long standing problem of creating a microscopic optical buffer, the key element of the future optical signal processing devices

    Fatigue crack initiation in AA2024: A coupled micromechanical testing and crystal plasticity study

    Get PDF
    A new combined experimental and modelling approach has been developed in order to understand the physical mechanisms that lead to crack nucleation in a polycrystalline aluminium alloy AA2024 undergoing cyclic loading. Four-point bending low-cycle fatigue tests were performed inside the chamber of a scanning electron microscope on specimens with a through-thickness central hole, introduced to localize stresses and strains in a small region on the top surface of the sample. Fatigue crack initiation and small crack growth mechanisms were analyzed through high-resolution scanning electron microscope images, local orientation measurements using electron-back-scattered-diffraction, and local strain measurements using digital image correlation. A crystal plasticity finite element model was developed to simulate the cyclic deformation behaviour of AA2024. Two-dimensional Voronoi-based microstructures were generated, and the material parameters for the constitutive equations (including both isotropic and kinematic hardening) were identified using monotonic and fully reversed cyclic tests. A commonly used fatigue crack initiation criterion found in the literature, the maximum accumulated plastic slip, was evaluated in the crystal plasticity finite element model but could not predict the formation of cracks away from the edge of the hole in the deformed specimens. A new criterion combining 2 parameters: The maximum accumulated slip over each individual (critical) slip system and the maximum accumulated slip over all slip systems were formulated to reproduce the experimental locations of crack nucleation in the microstructure

    Exploring the impact of cumulative testing on academic performance of undergraduate students in Spain

    Full text link
    The final publication is available at Springer via http://dx.doi.org/10.1007/s11092-014-9208-zFrequent testing provides opportunities for students to receive regular feedback and to increase their motivation. It also provides the instructor with valuable information on how course progresses, thus making it possible to solve the problems encountered before it is too late. Frequent tests with noncumulative contents have been widely analysed in the literature with inconclusive results. However, cumulative testing methods have hardly been reported in higher education courses. This paper analyses the effect of applying an assessment method based on frequent and cumulative tests on student performance. Our results show that, when applied to a microeconomics course, students who were assessed by a frequent, cumulative testing approach largely outperformed those assessed with a single final exam.Doménech I De Soria, J.; Blázquez Soriano, MD.; De La Poza, E.; Muñoz Miquel, A. (2015). Exploring the impact of cumulative testing on academic performance of undergraduate students in Spain. Educational Assessment, Evaluation and Accountability. 27(2):153-169. https://doi.org/10.1007/s11092-014-9208-zS153169272Adelman, HS, & Taylor, L. (1990). Intrinsic motivation and school misbehaviour some intervention implications. Journal of Learning Disabilities, 23, 541–550.Biggs, J, & Tang, C. (2007). Teaching for quality learning at university 3rd edn. Open University Press.Boston, C. (2002). The concept of formative assessment. Practical Assessment Research & Evaluation 8.Brown, GA, Bull, J, Pendlebury, M. (1997). Assessing Student Learning in Higher Education, 1st edn. Routledge.Cano, MD. (2011). Students’ involvement in continuous assessment methodologies: a case study for a distributed information systems course. IEEE Transactions on Education, 54, 442–451.Casem, ML (2006). Active learning is not enough. Journal of College Science Teaching, 35.Chen, J, & Lin, TF. (2008). Class attendance and exam performance a randomized experiment. The Journal of Economic Education, 39, 213–227.Chickering, AW, & Gamson, ZF. (1987). Seven principles for good practice in undergraduate education. American Association for Higher Education Bulletin, 39, 3–7.Crooks, TJ. (1988). The impact of classroom evaluation practices on students. Review of Educational Research, 58, 438–481.De Paola, M, & Scoppa, V. (2011). Frequency of examinations and student achievement in a randomized experiment. Economics of Education Review, 30, 1416–1429.Deck, W. (1998). The effects of frequency of testing on college students in a principles of marketing course, PhD thesis, Virginia Polytechnic Institute and State University. Virginia: Blacksburg.Dempster, FN. (1991). Synthesis of research on reviews and tests. Educational Leadership, 48, 71–76.Dochy, F. (2008). The Edumetric Quality of New Modes of Assessment: Some Issues and Prospects. Assessment, Learning and Judgement in Higher Education. Dordrecht: Springer Netherlands.Eikner, AE, & Montondon, L. (2001). Evidence on factors associated with success in intermediate accounting I. Accounting Educators’ Journal 13.Emerson, TLN, & Mencken, KD. (2011). Homework to require or not? online graded homework and student achievement Perspectives on Economic Education Research 7.Fulkerson, F, & Martin, G. (1981). Effects of exam frequency on student performance, evaluations of instructor, and test anxiety. Teaching of Psychology, 8, 90–93.Furnham, A, & Chamorro-Premuzic, T. (2005). Individual differences and beliefs concerning preference for university assessment methods. Journal of Applied Social Psychology, 35, 1968–1994.Gibbs, G, & Simpson, C. (2005). Conditions under which assessment supports students’ learning Learning and Teaching in Higher Education 1 (August 5, 2011)3–31.Haberyan, KA. (2003). Do weekly quizzes improve student performance on general biology exams?. The American Biology Teacher, 65, 110–114.Kling, N, McCorkle, D, Miller, C, Reardon, J. (2005). The impact of testing frequency on student performance in a marketing course. Journal of Education for Business, 81, 67–72.Kuh, GD (2003). What we’re learning about student engagement from NSSE Change 35.Kuo, T, & Simon, A. (2009). How many tests do we really need. College Teaching, 57, 156–160.Leeming, FC. (2002). The exam-a-day procedure improves performance in psychology classes. Teaching of Psychology, 29, 210–212.Lumsden, KG, Scott, A, Becker, WE. (1987). The economics student reexamined Male-female differences in comprehension. Journal of Economic Education, 18, 365–375.Marriott, P. (2009). Students’ evaluation of the use of online summative assessment on an undergraduate financial accounting module. British Journal of Educational Technology, 40, 237–254.Marriott, P, & Lau, A. (2008). The use of on-line summative assessment in an undergraduate financial accounting course. Journal of Accounting Education, 26, 73–90.McNabb, R, Pal, S, Sloane, P. (2002). Gender differences in educational attainment. the case of university students in england and wales. Economica, 69, 481–503.Miller, F. (1987). Test frequency, student performance and teacher evaluation in the basic marketing class. Journal of Marketing Education, 9, 14–19.Nicol, DJ, & Macfarlane Dick, D. (2006). Formative assessment and self-regulated learning, A model and seven principles of good feedback practice. Studies in Higher Education, 31, 199–218.Nowell, C, & Alston, RM. (2007). I thought I got an A! Overconfidence across the economics curriculum. The Journal of Economic Education, 38, 131–142.Race, P (1995). The art of assessing 1 New Academic 4.Scriven, M. (1967). The Methodology of Evaluation, vol 1 (pp. 39–83). Chicago: Rand McNally.Skinner, BF. (1974). About behaviorism. New York: Alfred A Knopf.Taras, M. (2005). Assessment - summative and formative - some theoretical reflections. British Journal of Educational Studies, 53, 466–478.Trotter, E. (2006). Student perceptions of continuous summative assessment. Assessment & Evaluation in Higher Education, 31, 505–521.Yorke, M. (2003). Formative assessment in higher education: Moves towards theory and the enhancement of pedagogic practice. Higher Education, 45, 477–501

    The crossroads of evidence-based medicine and health policy: implications for urology

    Get PDF
    As healthcare spending in the United States continues to rise at an unsustainable rate, recent policy decisions introduced at the national level will rely on precepts of evidence-based medicine to promote the determination, dissemination, and delivery of “best practices” or quality care while simultaneously reducing cost. We discuss the influence of evidence-based medicine on policy and, in turn, the impact of policy on the developing clinical evidence base with an eye to the potential effects of these relationships on the practice and provision of urologic care

    Fibre Distribution and the Process-Property Dilemma

    Get PDF
    The options for the fibre reinforcement of polymer matrix composites cover a range from short-fibre chopped strand mat, through woven fabric to unidirectional pre-impregnated (prepreg) reinforcements. The modelling of such materials may be simplified by assumptions such as perfect regular packing of fibres and the total absence of fibre waviness. However, these and other features such as the crimp or waviness in woven fabrics make real materials more complex than the simplified models. Clustering of fibres creates fibre-rich and resin-rich volumes (FRV and RRV respectively) in the composites. Prior to impregnation, large RRV will be pore-space that can expedite the flow of resin in liquid composite moulding processes (especially resin transfer moulding (RTM) and resin infusion under flexible tooling (RIFT). In the composite, the clustering of fibres tends to reduce the mechanical properties. The use of image processing and analysis can permit micro-/meso-structural characterisation which may correlate to the respective properties. This chapter considers the quantification of microstructure images in the context of the process-property dilemma for woven carbon-fibre reinforced composites with the aim of increasing understanding of the balance between processability and mechanical performance

    Delivering medical abortion at scale: a study of the retail market for medical abortion in Madhya Pradesh, India.

    Get PDF
    BACKGROUND: Medical abortion (mifepristone and misoprostol) has the potential to contribute to reduced maternal mortality but little is known about the provision or quality of advice for medical abortion through the private retail sector. We examined the availability of medical abortion and the practices of pharmacists in India, where abortion has been legal since 1972. METHODS: We interviewed 591 pharmacists in 60 local markets in city, town and rural areas of Madhya Pradesh. One month later, we returned to 359 pharmacists with undercover patients who presented themselves unannounced as genuine customers seeking a medical abortion. RESULTS: Medical abortion was offered to undercover patients by 256 (71.3%) pharmacists and 24 different brands were identified. Two thirds (68.5%) of pharmacists stated that abortion was illegal in India. Only 106 (38.5%) pharmacists asked clients the timing of the last menstrual period and 38 (13.8%) requested to see a doctor's prescription - a legal requirement in India. Only 59 (21.5%) pharmacists correctly advised patients on the gestational limit for medical abortion, 97 (35.3%) provided correct information on how many and when to take the tablets in a combination pack, and 78 (28.4%) gave accurate advice on where to seek care in case of complications. Advice on post-abortion family planning was almost nonexistent. CONCLUSIONS: The retail market for medical abortion is extensive, but the quality of advice given to patients is poor. Although the contribution of medical abortion to women's health in India is poorly understood, there is an urgent need to improve the practices of pharmacists selling medical abortion
    corecore