186,449 research outputs found
Health characteristics by occupation and industry of longest employment
No full textIncludes estimates on length of longest job held, limitation of activity, disability days, incidence of acute conditions, persons injured, hospitalizations, and utilization of medical and dental services of persons aged 17 years and over in the civilian noninstitutionalized population. These estimates are presented by occupation and industry of longest employment for those who had ever worked. Estimates are based on data collected in the National Health Interview Survey of 1980.By Sharon P. Cooper, Patricia A. Buffler, and Charles J. Cooper.Shipping list no.: 89-398-P.Includes bibliographical references (p. 14).198927634711101
Measurement of fluence at the D-line fast neutron facility at iThemba LABS
No full textMeasurements of fluence were made for the neutron beams produced at the fast neutron beam facility of iThemba LABS, using an NE213 organic liquid scintillator detector and a 238U fission ionisation chamber. Neutron beams were produced by irradiating a 6 mm natural lithium target with pulsed proton beams obtained from the k = 200 separated sector cyclotron. Three incident proton beam energies were used in this work, namely 65.99 MeV, 99.44 MeV and 203.33 MeV. From time-of-flight measurements with the NE213 scintillator, the spectral fluence of the neutron beams was obtained. Pulse shape discrimination was used to correct for gamma ray induced signals in the NE213 detector. Simultaneous measurements of the neutron beam flux were performed at 0° and 16°. The 238U detector was used to obtain peak fluence measurements relative to the 238U(n,f) cross section
Wilms' tumour: A systematic review of risk factors and meta-analysis
No full textWilms' tumour comprises 95% of all renal cancers among children less than 15 years of age. The purpose of this review is to examine the existing literature on perinatal and environmental risk factors for Wilms' tumour. A search for epidemiological studies that examined risk factors for Wilms' tumour was undertaken in Medline, LILACS, ISI Web of Science and Dissertation Abstracts. A total of 37 studies, including 14 cohort, 21 case-control and 2 case-cohort studies, were identified that examined environmental and perinatal risk factors. Most studies were from Western Europe and North America, and among case-control studies, 16 used randomly selected population-based controls. We observed a significantly increased risk of Wilms' tumour with maternal exposure to pesticides prior to the child's birth (OR = 1.37 [95% CI 1.09, 1.73]), high birthweight (OR = 1.36 [95% CI 1.12, 1.64]) and preterm birth (OR = 1.44 [95% CI 1.14, 1.81]), although the results regarding pesticide exposure may be subject to publication bias (Egger's test, P = 0.09). Further analyses to adjust for the heterogeneity in the results for high birthweight and preterm birth did not statistically change the significance of the results. Additionally, an increased though not statistically significant risk of Wilms' tumour was associated with maternal hypertension (OR = 1.30 [95% CI 0.99, 1.72]), and, compared with the first born, being a second or later birth was associated with a significantly decreased risk (OR = 0.82 [95% CI 0.71, 0.95]). This review suggests a role for several perinatal and environmental risk factors in the aetiology of Wilms' tumour. © 2010 Blackwell Publishing Ltd
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Strategies adopted by undergraduate physics students when modelling solutions to hands-on tasks
No full textIncludes bibliographical references.Over the last three to four decades there has been a focus on the role of models and modelling in physics education. At the same time, there has also been a move away from the use of recipe-style tasks in physics laboratories to inquiry-based problem solving. From the ensuing research, model-based views of physics have emerged which have contributed to the fields of pedagogy as well as epistemology; the contribution depending on whether the research interest has been that of education or philosophy of science. And while there is still some consensus seeking on the nature and definitions of modelling, there has in recent years been a shift to research questions that consider how models are constructed by students when engaged in hands-on tasks. Model-based instruction courses have been researched at length, but there is a perceived gap in the research that considers the hands-on strategies that are actually employed by 1st-year university students who are in a teaching and learning environment in which the physics curriculum emphasises the modelling of real world systems. This study contributes to this research area in that it investigates the strategies students actually adopt when engaged in student-driven, hands-on laboratory tasks and interprets those strategies in terms of a particular model-based view of physics; a model-based view that posits that the processes of modelling are those of the particularisation and application of physics theory, the idealisation and approximation of real world phenomena, and the eventual realisation of a conceptual model
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Mechanistic considerations in the molecular epidemiology of head and neck cancer
No full textHead and neck cancer occurs through a complex multistage process that is likely to involve a combination of carcinogen exposure and genetic susceptibility. The primary cause of head and neck cancer are alcohol consumption and cigarette smoking, although the carcinogenic mechanism for these agents is unclear. Molecular epidemiological studies of head and neck cancer can help to clarify the carcinogenic process in several ways, including identification of metabolizing genes which increase the risk of head and neck cancer, identification of DNA adducts in target cells and analysis of specific gene mutations and their relationship with exposure. This review summarizes current knowledge on the molecular epidemiology of head and neck cancer and attempts to identify those areas where future studies may prove fruitful
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