954 resultados para Directional over-current relays
Resumo:
Although oral piercing has been an uncommon practice in the Western world, the insertion of metal objects into intra-oral and peri-oral pierced sites is growing in popularity. Tongue piercing is one such practice whereby a metal barbell is inserted into the tongue after piercing with a 14-16 gauge needle. Pain, swelling and infection are the most serious consequences associated with this procedure. Other adverse outcomes include mucosal or gingival trauma, chipped or fractured teeth, increased salivary flow, calculus build-up, and interference with speech, mastication and swallowing. This article presents a case report on tongue piercing and highlights the procedure involved. Special attention is given to complications and dental implications associated with such an unusual practice.
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Objective-To examine changes in the prevalence of cigarette smoking in 35 study populations of the World Health Organisation's MONICA Project. Design-Data from two independent, community-based surveys conducted, on average, five years apart. Setting-Geographically defined populations in 21 countries mainly in eastern and western Europe. Subjects-Randomly selected men and women aged 25-64 years. Numbers of participants in each study population ranged from 586 to 2817 in each survey. Main outcome measures-Changes in proportions of current smokers, ex-smokers, and never-smokers by age and sex using data collected by standardised methods. Results-Among men, smoking prevalence decreased in most populations, by three to four percentage points over five years. In Beijing, however, it increased in all age groups-overall by 11 percentage points. Among women there were increases in smoking in about half the populations. The increases were mainly in the age group 35-54 years and often in those populations where smoking prevalence among women has been relatively low. Conclusions-Smoking initiation by middle-aged women in parts of southern and eastern Europe and among men of all ages in Beijing is a matter of concern. The various public health measures that have helped to reduce smoking among men in developed countries should be vigorously extended to these other groups now at growing risk of smoking-related disease.
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Objective: To design, introduce, and evaluate STD syndrome packets containing recommended drugs for each syndrome, four condoms, a partner treatment card, and a patient information leaflet, with the goal of improving sexually transmitted disease (STD) case management. Methods: Packet design evolved around available packaging technology, informed by pilot testing with nurses working in primary care clinics, doctors in private medical practices, and patients with an STD, in Hlabisa, South Africa. Evaluation 1 year later included analysis of distribution records and interviews with 16 nurses and 61 patients. Results: A cheap packet (2 U, S, cents each, excluding contents) compatible with current legislation was designed and introduced to six public sector clinics and as a short pilot to five private medical practices, Four thousand eighty-five packets were distributed to the clinics, equivalent to approximately 115% of the STDs reported over that period. All 16 nurses reported using the packets, but only 63% did so all the time because of occasional supply problems, All believed the packets improved treatment by saving time (75%), improving supply of condoms and partner cards (44%), and making treatment easier (56%), Patients also responded positively, and most said they would buy a packet (up to $5) at a pharmacy (84%) or store (63%) if available. Conclusions: The STD syndrome packets have the potential to improve STD syndromic management by standardizing therapy and improving the supply of condoms, partner cards, and information leaflets. Packets are popular with practitioners and patients, but consistent supply is essential for maximal impact, There may be scope for social marketing of the packets, which could further increase use.
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Objectives: A controlled trial to compare the effectiveness of verbal advice from a family physician (FP) combined with either standard or tailored written information on physical activity in increasing the levels of physical activity in sedentary patients. Design: Sedentary patients (n = 763) were recruited through ten family practices and allocated to a control group or one of two intervention groups, Brief advice on physical activity was given by the FP during the consultation and either a standard or tailored pamphlet was mailed to the home address of patients assigned to the intervention groups within two days of their visit to the FP. Results: The response to follow-up, via a postal survey at one, six, and twelve months after the index consultation was 70%, 60%, and 57%, respectively. Treating all nonresponders as sedentary, the results revealed that although more tailored subjects reported some physical activity at each follow-up compared with the standard group, these differences were not significant, Furthermore, there was no significant difference in movement across the stages of readiness to exercise at follow-up between subjects in the tailored group who received material targeting their current stage (precontemplation or contemplation) and the standard group who received generic material that addressed both stages. Conclusion: These findings do not concur with the results from previous research in the areas of nutrition and smoking cessation where additional benefits were seen with a tailored intervention. Future research on the application of the principles of tailoring to the promotion of physical activity should focus on identifying which, if any, physical, social, psychological or environmental variables should be addressed to produce improved outcomes over and above the effects of well designed generic materials. (C) 1999 American Journal of Preventive Medicine.
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A quantum Markovian master equation is derived to describe the current noise in resonant tunneling devices. This equation includes both incoherent and coherent quantum tunneling processes. We show how to obtain the population master equation by adiabatic elimination of quantum coherences in the presence of elastic scattering. We calculate the noise spectrum for a double well device and predict subshot noise statistics for strong tunneling between the wells. The method is an alternative to Green's function methods and population master equations for very small coherently coupled quantum dots.
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Carbon dioxide reforming of methane into syngas over Ni/gamma-Al2O3 catalysts was systematically studied. Effects of reaction parameters on catalytic activity and carbon deposition over Ni/gamma-Al2O3 catalysts were investigated. It is found that reduced NiA1204, metal nickel, and active species of carbon deposited were the active sites for this reaction. Carbon deposition on Ni/gamma Al2O3 varied depending on the nickel loading and reaction temperature and is the major cause of catalyst deactivation. Higher nickel loading produced more coke on the catalysts, resulting in rapid deactivation and plugging of the reactor. At 5 wt % Ni/gamma-Al2O3 catalyst exhibited high activity and much lesser magnitude of deactivation in 140 h. Characterization of carbon deposits on the catalyst surface revealed that there are two kinds of carbon species (oxidized and -C-C-) formed during the reaction and they showed different reactivities toward hydrogenation and oxidation. Kinetic studies showed that the activation energy for CO production in this reaction amounted to 80 kJ/mol and the rate of CO production could be described by a Langmuir-Hinshelwood model.
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Catalytic conversion of N2O to N-2 over Cu- and Co-impregnated activated carbon catalysts (Cu/AC and Co/AC) was investigated. Catalytic activity measurements were carried out in a fixed-bed flow reactor at atmospheric pressure. The catalysts were characterized by N-2 adsorption, X-ray diffraction (XRD) and thermogravimetric analysis (TGA). This study aimed to provide insights into the following aspects: the metal dispersion, changes in pore structure, influence of catalyst loading on reaction, and reaction mechanism. Increasing loading of Co or Cu led to decreasing dispersion, but 20 wt % loading was an upper limit for optimal activities in both cases, with too high loading causing sintering of metal. Co exhibited a relatively better dispersion than Cu. Impregnation of metal led to a large decrease in surface area and pore volume, especially for 30 wt % of loading. 20 wt % of loading has proved to be the optimum for both Cu and Co, which shows the highest activity. Both N2O-Co/AC and -Cu/AC reactions are based upon a redox mechanism, but the former is limited by the oxygen transfer from catalysts to carbon, while N2O chemisorption on the surface of Cu catalyst controls the latter. The removal of oxygen from cobalt promotes the activity of Co/AC, but it is beneficial for Cu/AC to keep plenty of oxygen to maintain the intermediate oxidation of copper-Cu1+. The different nature of the two catalysts and their catalytic reaction mechanisms are closely related to their different electronegativities.
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Recent advances in the application of bioelectrical impedance analysis (BIA) have indicated that a more accurate approach to the estimation of total body water is to consider the impedance of the various body segments rather than simply that of the whole body. The segmental approach necessitates defining and locating the physical demarcation between both the trunk and leg and the trunk and arm. Despite the use of anatomical markers, these points of demarcation are difficult to locate with precision between subjects. There are also technical problems associated with the regional dispersion of the current distribution from one segment (cylinder) to another of different cross-sectional area. The concept of equipotentials in line with the proximal aspects of the upper land lower) limbs along the contralateral limbs was investigated and, in particular, the utility of this concept in the measurement of segmental bioimpedance. The variation of measured segmental impedance using electrode sites along these equipotentials was less than 2.0% for all of the commonly used impedance parameters. This variation is approximately equal to that expected from biological variation over the measurement time. It is recommended that the electrode sites, for the measurement of segmental bioelectrical impedance in humans, described herein are adopted in accordance with the proposals of the NM Technology Assessment Conference Statement.
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Catalytic conversion of N2O to N-2 With potassium catalysts supported on activated carbon (K/AC) was investigated. Potassium proves to be much more active and stable than either copper or cobalt because potassium possesses strong abilities both for N2O chemisorption and oxygen transfer. Potassium redispersion is found to play a critical role in influencing the catalyst stability. A detailed study of the reaction mechanism was conducted based upon three different catalyst loadings. It was found that during temperature-programmed reaction (TPR), the negative oxygen balance at low temperatures (< 50 degrees C) is due to the oxidation of the external surface of potassium oxide particles, while the bulk oxidation accounts for the oxygen accumulation at higher temperatures (below ca. 270 degrees C). N2O is beneficial for the removal of carbon-oxygen complexes because of the formation of CO2 instead of CO and because of its role in making the chemisorption of produced CO2 on potassium oxide particles less stable. A conceptual three-zone model was proposed to clarify the reaction mechanism over K/AC catalysts. CO2 chemisorption at 250 degrees C proves to be an effective measurement of potassium dispersion. (C) 1999 Academic Press.
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The effect of acidic treatments on N2O reduction over Ni catalysts supported on activated carbon was systematically studied. The catalysts were characterized by N-2 adsorption, mass titration, temperature-programmed desorption (TPD), and X-ray photoelectron spectrometry (XPS). It is found that surface chemistry plays an important role in N2O-carbon reaction catalyzed by Ni catalyst. HNO3 treatment produces more active acidic surface groups such as carboxyl and lactone, resulting in a more uniform catalyst dispersion and higher catalytic activity. However, HCl treatment decreases active acidic groups and increases the inactive groups, playing an opposite role in the catalyst dispersion and catalytic activity. A thorough discussion of the mechanism of the N2O catalytic reduction is made based upon results from isothermal reactions, temperature-programmed reactions (TPR) and characterization of catalysts. The effect of acidic treatment on pore structure is also discussed. (C) 1999 Elsevier Science B.V. All rights reserved.
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This paper describes a hybrid numerical method for the design of asymmetric magnetic resonance imaging magnet systems. The problem is formulated as a field synthesis and the desired current density on the surface of a cylinder is first calculated by solving a Fredholm equation of the first kind. Nonlinear optimization methods are then invoked to fit practical magnet coils to the desired current density. The field calculations are performed using a semi-analytical method. A new type of asymmetric magnet is proposed in this work. The asymmetric MRI magnet allows the diameter spherical imaging volume to be positioned close to one end of the magnet. The main advantages of making the magnet asymmetric include the potential to reduce the perception of claustrophobia for the patient, better access to the patient by attending physicians, and the potential for reduced peripheral nerve stimulation due to the gradient coil configuration. The results highlight that the method can be used to obtain an asymmetric MRI magnet structure and a very homogeneous magnetic field over the central imaging volume in clinical systems of approximately 1.2 m in length. Unshielded designs are the focus of this work. This method is flexible and may be applied to magnets of other geometries. (C) 1999 Academic Press.
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This paper studies life-cycle preferences over consumption and health status. We show that cost-effectiveness analysis is consistent with cost-benefit analysis if the Lifetime utility function is additive over time, multiplicative in the utility of consumption and the utility of health status, and if the utility of consumption is constant over time. We derive the conditions under which the lifetime utility function takes this form, both under expected utility theory and under rank-dependent utility theory, which is currently the most important nonexpected utility theory. If cost-effectiveness analysis is consistent with cost-benefit analysis, it is possible to derive tractable expressions for the willingness to pay for quality-adjusted life-years (QALYs). The willingness to pay for QALYs depends on wealth, remaining life expectancy, health status, and the possibilities for intertemporal substitution of consumption. (C) 1999 Elsevier Science B.V. All rights reserved.
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Large numbers of adults of certain species of butterfly flying in an apparently 'purposeful' manner are often noted by entomologists and the general public. Occasionally, these are recorded in the literature. Using these records we summarise information regarding the direction of movement in Australian butterflies and test whether there are consistent patterns that could account for known seasonal shifts in geographical range. The data were analysed using contingency tables and directionality statistics. Vanessa itea, Vanessa kershawi, Danaus plexippus, Danaus chrysippus and Badamia exclamationis flew predominately south in the spring-summer and north in the autumn-winter. Tirumala hamata has a strong southern component to its flight in spring but, as in Euploea core, appears non-directional in the autumn. For many supposedly known migratory species, the number of literature records are few, particularly in one season (mainly autumn). Thus, for Appias paulina, four of seven records were south in the spring-summer, as were six of nine records for Catopsilia pomona, and three of five for Zizina labradus. For Belenois java, flight records were only available for the spring and these showed geographical differences; predominantly north-west in northern Australia (Queensland) and south-west in southern Australia (Victoria, New South Wales). There were too few records for Papilio demoleus in the literature (four only) to draw any conclusions. Major exceptions to the seasonal trend of south in the spring and north in the autumn were Junonia villida, which showed a predominant north-westward direction in both seasons, and Eurema smilax, with a predominant southern or western flight in both seasons. We discuss these species specific trends in migration direction in relation to seasonal shifts in suitable habitat conditions, possible cues used in orientation and in timing changes in direction.
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The aim of this paper is to examine distributions of schizophrenia and general population births over time in order to determine whether (a) the pattern has changed over time, (b) any pattern was similar for both males and females, and (c) whether there is any indication that there is any relationship between the changes in pattern between schizophrenia and general population births. Birth month and year for 7807 individuals with ICD8/9 schizophrenia were gained from the Queensland Mental Health Statistical System for 1914-1975. Monthly births for the general population in Queensland for the same period were obtained from the Australian Bureau of Statistics. For each decade we obtained two comparisons, (1) between two 'seasons' (summer-autumn/winter-spring), and (2) between the third (coldest) quarter and the remaining quarters. Based on expected contrasts from general population proportions, odds ratios and their confidence intervals were used to analyse these comparisons for all subjects, and for males and females separately. The seasonality found in our previous studies was again evident (OR 1.09; 95% CI= 1.01-1.17). However there was no significant change in its pattern over time either for the total group or for males and females separately. When the general population births alone were examined using the same contrasts, seasonality was also observed, but here there were fluctuations over time. These results suggest that exposures linked to changes in general population births over time should be examined in disorders such as schizophrenia which demonstrate seasonality in births. The Stanley Foundation supported this project.