80 research outputs found
On The Mechanism And Behavior Of Plasma
The charged particles’ action of and fields have three diverse levels of modeling, Starting with the simplest one to the most complicated. In this paper we consider the generalization of Newtonian force law in geometrical term is to describe charged particles’ (plasma) trajectories on electromagnetic fields in the kinetic or microscopic model. Keyword: Gravitational field, Time–dependent Flow, Integral Curves, Exterior Differential Systems, Kinetic Energy
On Some Fourier Asymptotes of Fractal Measures
We give a condition for a quasi-regular set to satisfy certain density, if is absolutely continuous with respect to and an inequality was hold. We investigate a Fourier asymptotic of fractal measures with a sharp bound. For a continuous measure with a monotone discrete sequence a best estimate was proved. Keywords: Maximal functions, Wiener’s Measures, Fractal Measures, quasi-regula
Interacties en interdependenties tussen prijs, kwaliteit en communicatie: Een overzicht en kritische evaluatie.
Use of Balloon-Tipped Catheters in the Critically Ill Child
A retrospective study of our experience in the placement of 19 consecutive balloon-tipped catheters in the pulmonary artery of 18 children disclosed that the procedure can be performed with relative ease in the intensive care unit without the aid of fluoroscopy. Insertion of the catheters was not associated with any serious complications. Catheter malfunction, however, occurred in 9 of 18 patients: balloon rupture in 6 and clot formation in 3. Comparison of pulmonary capillary pressure through a balloon-tipped catheter and venous pressure through a central venous line indicates that, in the absence of significant pulmonary disease requiring high positive end expiratory pressure, or significant left heart dysfunction, a central venous pressure line is frequently adequate for monitoring right heart pressures and as a guidance to fluid therapy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67256/2/10.1177_000992288202100302.pd
Development of a global landscape of undergraduate physics laboratory courses
Physics Education Research (PER) is a global endeavour, with a wealth of work
performed at a variety of institutions worldwide. However, results from
research into undergraduate physics laboratory courses is often difficult to
compare due to the broad variations in courses. We have created a survey to
help classify these courses to compare and contrast them, which will be useful
in two key endeavours: comparisons between PER studies and providing useful
data for individual instructors hoping to improve their courses, thus providing
information relevant to both researchers and instructors. While we are still in
the process of collecting sufficient data to create a full taxonomy of
laboratory courses, we present here details of the survey creation itself, as
well as a first look at the data collected, which includes a broad landscape of
lab courses in 41 countries. We used both quantitative and qualitative methods
in analyzing the data collected. Some of these results include similarities
between courses, such as students often using pre-constructed apparatuses and
that instructors hope for students to learn technical skills. We also find
differences in courses, such as in the number and types of goals of the course,
as well as the activities students participate in.Comment: 38 pages, 15 figure
Environmental risk factors of pregnancy outcomes: A summary of recent meta-analyses of epidemiological studies.
Background Various epidemiological studies have suggested associations between environmental exposures and pregnancy outcomes. Some studies have tempted to combine information from various epidemiological studies using meta-analysis. We aimed to describe the methodologies used in these recent meta-analyses of environmental exposures and pregnancy outcomes. Furthermore, we aimed to report their main findings. Methods We conducted a bibliographic search with relevant search terms. We obtained and evaluated 16 recent meta-analyses. Results The number of studies included in each reported meta-analysis varied greatly, with the largest number of studies available for environmental tobacco smoke. Only a small number of the studies reported having followed meta-analysis guidelines or having used a quality rating system. Generally they tested for heterogeneity and publication bias. Publication bias did not occur frequently. The meta-analyses found statistically significant negative associations between environmental tobacco smoke and stillbirth, birth weight and any congenital anomalies; PM2.5 and preterm birth; outdoor air pollution and some congenital anomalies; indoor air pollution from solid fuel use and stillbirth and birth weight; polychlorinated biphenyls (PCB) exposure and birth weight; disinfection by-products in water and stillbirth, small for gestational age and some congenital anomalies; occupational exposure to pesticides and solvents and some congenital anomalies; and agent orange and some congenital anomalies. Conclusions The number of meta-analyses of environmental exposures and pregnancy outcomes is small and they vary in methodology. They reported statistically significant associations between environmental exposures such as environmental tobacco smoke, air pollution and chemicals and pregnancy outcomes
Congenital anomalies in newborns to women employed in jobs with frequent exposure to organic solvents - a register-based prospective study
<p>Abstract</p> <p>Background</p> <p>The foetal effects of occupational exposure to organic solvents in pregnancy are still unclear. Our aim was to study the risk of non-chromosomal congenital anomalies at birth in a well-defined population of singletons born to women employed as painters and spoolers in early pregnancy, compared to women in non-hazardous occupations.</p> <p>Method</p> <p>The study population for this prospective cohort study was singleton newborns delivered to working mothers in the industrial community of Mončegorsk in the period 1973-2005. Occupational information and characteristics of the women and their newborns was obtained from the local population-based birth register.</p> <p>Results</p> <p>The 597 women employed as painters, painter-plasterers or spoolers had 712 singleton births, whereof 31 (4.4%) were perinatally diagnosed with 37 malformations. Among the 10 561 newborns in the group classified as non-exposed, 397 (3.9%) had one or more malformations. The overall prevalence in the exposed group was 520/10 000 births [95% confidence limits (CL): 476, 564], and 436/10 000 births (95% CL: 396, 476) in the unexposed. Adjusted for young maternal age, smoking during pregnancy, maternal congenital malformation and year of birth, the odds ratio (OR) was 1.24 (95% CL: 0.85, 1.82); for multiple anomalies it was 1.54 (95% CL: 0.66, 3.59).</p> <p>The largest organ-system specific difference in prevalence between the two groups was observed for malformations of the circulatory system: 112/10 000 (95% CL: 35, 190) in the exposed group, and 42/10 000 (95% CL: 29, 54) in the unexposed, with an adjusted OR of 2.03 (95% CL: 0.85, 4.84). The adjusted ORs for malformations of the genital organs and musculoskeletal system were 2.24 (95% CI: 0.95, 5.31) and 1.12 (95% CI: (0.62, 2.02), respectively.</p> <p>Conclusion</p> <p>There appeared to be a higher risk of malformations of the circulatory system and genital organs at birth among newborns to women in occupations with organic solvent exposure during early pregnancy (predominantly employed as painters). However, the findings were not statistically conclusive. Considering that these two categories of malformations are not readily diagnosed perinatally, the difference in prevalence between the exposed and unexposed may have been underestimated.</p
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