954 resultados para Capacitor-clamped three-level inverter
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The objective of the present study was to evaluate breathing pattern, thoracoabdominal motion and muscular activity during three breathing exercises: diaphragmatic breathing (DB), flow-oriented (Triflo II) incentive spirometry and volume-oriented (Voldyne) incentive spirometry. Seventeen healthy subjects (12 females, 5 males) aged 23 ± 5 years (mean ± SD) were studied. Calibrated respiratory inductive plethysmography was used to measure the following variables during rest (baseline) and breathing exercises: tidal volume (Vt), respiratory frequency (f), rib cage contribution to Vt (RC/Vt), inspiratory duty cycle (Ti/Ttot), and phase angle (PhAng). Sternocleidomastoid muscle activity was assessed by surface electromyography. Statistical analysis was performed by ANOVA and Tukey or Friedman and Wilcoxon tests, with the level of significance set at P < 0.05. Comparisons between baseline and breathing exercise periods showed a significant increase of Vt and PhAng during all exercises, a significant decrease of f during DB and Voldyne, a significant increase of Ti/Ttot during Voldyne, and no significant difference in RC/Vt. Comparisons among exercises revealed higher f and sternocleidomastoid activity during Triflo II (P < 0.05) with respect to DB and Voldyne, without a significant difference in Vt, Ti/Ttot, PhAng, or RC/Vt. Exercises changed the breathing pattern and increased PhAng, a variable of thoracoabdominal asynchrony, compared to baseline. The only difference between DB and Voldyne was a significant increase of Ti/Ttot compared to baseline. Triflo II was associated with higher f values and electromyographic activity of the sternocleidomastoid. In conclusion, DB and Voldyne showed similar results while Triflo II showed disadvantages compared to the other breathing exercises.
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Low-level lasers are used at low power densities and doses according to clinical protocols supplied with laser devices or based on professional practice. Although use of these lasers is increasing in many countries, the molecular mechanisms involved in effects of low-level lasers, mainly on DNA, are controversial. In this study, we evaluated the effects of low-level red lasers on survival, filamentation, and morphology of Escherichia colicells that were exposed to ultraviolet C (UVC) radiation. Exponential and stationary wild-type and uvrA-deficientE. coli cells were exposed to a low-level red laser and in sequence to UVC radiation. Bacterial survival was evaluated to determine the laser protection factor (ratio between the number of viable cells after exposure to the red laser and UVC and the number of viable cells after exposure to UVC). Bacterial filaments were counted to obtain the percentage of filamentation. Area-perimeter ratios were calculated for evaluation of cellular morphology. Experiments were carried out in duplicate and the results are reported as the means of three independent assays. Pre-exposure to a red laser protected wild-type and uvrA-deficient E. coli cells against the lethal effect of UVC radiation, and increased the percentage of filamentation and the area-perimeter ratio, depending on UVC fluence and physiological conditions in the cells. Therapeutic, low-level red laser radiation can induce DNA lesions at a sub-lethal level. Consequences to cells and tissues should be considered when clinical protocols based on this laser are carried out.
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The viscoelastic properties of edible films can provide information at the structural level of the biopolymers used. The objective of this work was to test three simple models of linear viscoelastic theory (Maxwell, Generalized Maxwell with two units in parallel, and Burgers) using the results of stress relaxation tests in edible films of myofibrillar proteins of Nile Tilapia. The films were elaborated according to a casting technique and pre-conditioned at 58% relative humidity and 22ºC for 4 days. The testing sample (15mm x 118mm) was submitted to tests of stress relaxation in an equipment of physical measurements, TA.XT2i. The deformation, imposed to the sample, was 1%, guaranteeing the permanency in the domain of the linear viscoelasticity. The models were fitted to experimental data (stress x time) by nonlinear regression. The Generalized Maxwell model with two units in parallel and the Burgers model represented the relaxation curves of stress satisfactorily. The viscoelastic properties varied in a way that they were less dependent on the thickness of the films.
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The artisanal production of cachaça, a beverage obtained by the fermentation of sugar cane juice after distillation, especially by small-sized producers, has traditionally used natural ferment ("fermento caipira") which consists of sugar cane juice with crushed corn, powdered rice, or citrus fruits. In despite of the difficulties in quality control due to the high level of contaminants and longer periods of preparation, the sensorial quality of the beverage may be attributed to the physiological activities of wild yeasts and even bacteria present during fermentation when this ferment is used. In this context, the aim here was to evaluate the microbiological (yeasts) and physicochemical characteristics of sugar cane juice extracted from different parts of three different varieties (RB72454, RB835486, and RB867515) of the cane stalk (lower, medium, and upper sections) in three harvesting periods (from May to December 2007) in an area under organic management. The juice from the upper section (from the eleventh internode to the top) of the sugar cane stalk could be indicated for the preparation of the natural ferment since it is as a source of yeasts and reducing sugars, especially the variety RB867515. Due to the seasonality, the best period for using this part of the sugar cane stalk is at the beginning of harvesting when the phenolic compounds are at low concentration, but there are higher number of Saccharomyces population and other yeast species. The high acidity in this section of the plant could result in a better control of bacterial contamination. These findings explain the traditional instructions of adding the upper sections for the preparation of natural ferment and can help its management in order to get a better performance with respect to organic cachaça production.
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AbstractMaize is considered a source of carotenoids; however, these compounds are highly unstable, degraded by high temperatures, exposure to light and presence of oxygen. The objective of this work was to evaluate the influence of the moisture and type of drying applied to grains on the level of carotenoids in yellow maize. The experiment was conducted in a completely randomized design (2 × 4 factorial), two levels of initial moisture at the harvest (22 and 19%) and three types of drying (in the sun; in the shade and in a dryer) and control (no drying). The samples of grains after drying with 12% of final moisture were analyzed by concentration of total carotenoids, carotenes (α-carotene + β-carotene), monohydroxilated carotenoids (β-cryptoxanthin), and xanthophylls (lutein + zeaxanthin). Initial moisture, type of drying and the interaction between moisture versus drying influence (p≤0.05) the levels of carotenoids in grains. This is the first report about the drying conditions and harvest’s initial moisture as influence on the profile and content of carotenoids in maize grains. Based on the results, this work suggested that the harvest be carried out preferably when the grains present 22% humidity, with drying in a dryer or in shade for further use or storage.
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This study discusses the nature of informal learning process in business organizations, and the importance of different organization-level factors in this process. The purpose of this study is to understand the role of organization-level factors on informal learning process with three subquestions: how informal learning process takes place in business organizations, what organization-level factors affects informal learning process, and how informal learning process is affected by organizational-level factors. The theoretical background of this study includes literatures on the concept of informal learning, its process, and organization-level factors that can affect informal learning process. The empirical research has been conducted in this study by face-to-face interviews. The interviews were conducted between June and August 2015 in Dhaka, Bangladesh. Thirteen interviews were made with the employees from different hierarchical levels from four freight forwarding MNCs in Bangladesh. Constant comparative analysis has been used to process the collected data until reaching a level of saturation. The empirical research found that all the phases in an informal learning process are not linear and sequential, and the role of organization-level factors on each phase varies with the degree and nature of each factor. In addition, the results also revealed that all the organization-level factors do not interact with each other while playing their role on informal learning process. The findings of this study considerably extend our understanding of the important role of HRD, manager, colleague, culture, and work structure on informal learning process in the workplace. However, future research in different organizational contexts is required to generalize the findings of this study.
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This study discusses the nature of informal learning process in business organizations, and the importance of different organization-level factors in this process. The purpose of this study is to understand the role of organization-level factors on informal learning process with three subquestions: how informal learning process takes place in business organizations, what organizationlevel factors affects informal learning process, and how informal learning process is affected by organizational-level factors. The theoretical background of this study includes literatures on the concept of informal learning, its process, and organization-level factors that can affect informal learning process. The empirical research has been conducted in this study by face-to-face interviews. The interviews were conducted between June and August 2015 in Dhaka, Bangladesh. Thirteen interviews were made with the employees from different hierarchical levels from four freight forwarding MNCs in Bangladesh. Constant comparative analysis has been used to process the collected data until reaching a level of saturation. The empirical research found that all the phases in an informal learning process are not linear and sequential, and the role of organization-level factors on each phase varies with the degree and nature of each factor. In addition, the results also revealed that all the organization-level factors do not interact with each other while playing their role on informal learning process. The findings of this study considerably extend our understanding of the important role of HRD, manager, colleague, culture, and work structure on informal learning process in the workplace. However, future research in different organizational contexts is required to generalize the findings of this study.
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This study assessed the effectiveness of a reciprocal teaching program as a method of teaching reading comprehension, using narrative text material in a t.ypical grade seven classroom. In order to determine the effectiveness of the reciprocal teaching program, this method was compared to two other reading instruction approaches that, unlike rcciprocal teaching, did not include social interaction components. Two intact grade scven classes, and a grade seven teacher, participated in this study. Students were appropriately assigned to three treatment groups by reading achievement level as determined from a norm-referenced test. Training proceeded for a five week intervention period during regularly scheduled English periods. Throughout the program curriculum-based tests were administered. These tests were designed to assess comprehension in two distinct ways; namely, character analysis components as they relate to narrative text, and strategy use components as they contribute to student understanding of narrative and expository text. Pre, post, and maintenance tests were administered to measure overall training effects. Moreover, during intervention, training probes were administered in the last period of each week to evaluate treatment group performance. AU curriculum-based tests were coded and comparisons of pre, post, maintenance tests and training probes were presented in graph form. Results showed that the reciprocal group achieved some improvement in reading comprehension scores in the strategy use component of the tests. No improvements were observed for the character analysis components of the curriculum-based tests and the norm-referenced tests. At pre and post intervention, interviews requiring students to respond to questions that addressed metacomprehension awareness of study strategies were administered. The intelviews were coded and comparisons were made between the two intelVicws. No significant improvements were observed regarding student awareness of ten identified study strategies . This study indicated that reciprocal teaching is a viable approach that can be utilized to help students acquire more effective comprehension strategies. However, the maximum utility of the technique when administered to a population of grade seven students performing at average to above average levels of reading achievement has yet to be determined. In order to explore this issue, the refinement of training materials and curriculum-based measurements need to be explored. As well, this study revealed that reciprocal teaching placed heavier demands on the classroom teacher when compared to other reading instruction methods. This may suggest that innovative and intensive teacher training techniques are required before it is feasible to use this method in the classroom.
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Three grade three mathematics textbooks were selected arbitrarily (every other) from a total of six currently used in the schools of Ontario. These textbooks were examined through content analysis in order to determine the extent (i. e., the frequency of occurrence) to which problem solving strategies appear in the problems and exercises of grade three mathematics textbooks, and how well they carry through the Ministry's educational goals set out in The Formative Years. Based on Polya's heuristic model, a checklist was developed by the researcher. The checklist had two main categories, textbook problems and process problems and a finer classification according to the difficulty level of a textbook problem; also six commonly used problem solving strategies for the analysis of a process problem. Topics to be analyzed were selected from the subject guideline The Formative Years, and the same topics were selected from each textbook. Frequencies of analyzed problems and exercises were compiled and tabulated textbook by textbook and topic by topic. In making comparisons, simple frequency count and percentage were used in the absence of any known criteria available for judging highor low frequency. Each textbook was coded by three coders trained to use the checklist. The results of analysis showed that while there were large numbers of exercises in each textbook, not very many were framed as problems according to Polya' s model and that process problems form a small fraction of the number of analyzed problems and exercises. There was no pattern observed as to the systematic placement of problems in the textbooks.
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This study was particularly aimed at the examinations and the effect they have on schooling at the secondary school level in Zimbabwe. The views and opinions of teachers on the use of terminal examinations for certification and the influence they are seen to have on teachers' approach to the curriculum were examined. The literature has shown that there is widespread criticism of the justice and effects of terminal examinations. It is argued that they lead to an over-emphasis of that which is measured, knowledge and intellectual ability, at the expense of that kind of education progress which is almost impossible to measure in an end-of-the-course assessment. Three hundred and six secondary school teachers responded to a survey which asked for teachers' perceptions of examinations and the curriculum. The findings of this study indicated that teaching is structured towards examinations. Although teachers are trying to teach and develop reasoning skills and other activities, the pressure of examinations and the importance of doing well in them force teachers to restrict themselves to examination requirements.
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This study investigates instructors’ perceptions of reading instruction and difficulties among Language Instruction for Newcomers to Canada (LINC) Level 1-3 learners. Statistics Canada reports that 60% of immigrants possess inadequate literacy skills. Newcomers are placed in classes using the Canadian Language Benchmarks but large, mixed-level classes create little opportunity for individualized instruction, leading some clients to demonstrate little change in their reading benchmarks. Data were collected (via demographic questionnaires, semi-structured interviews, teaching plans, and field study notes) to create a case study of five LINC instructors’ perceptions of why some clients do not progress through the LINC reading levels as expected and how their previous experiences relate to those within the LINC program. Qualitative analyses of the data revealed three primary themes: client/instructor background and classroom needs, reading, strategies, methods and challenges, and assessment expectations and progress, each containing a number of subthemes. A comparison between the themes and literature demonstrated six areas for discussion: (a) some clients, specifically refugees, require more time to progress to higher benchmarks; (b) clients’ level of prior education can be indicative of their literacy skills; (c) clients with literacy needs should be separated and placed into literacy-specific classes; (d) evidence-based approaches to reading instruction were not always evident in participants’ responses, demonstrating a lack of knowledge about these approaches; (e) first language literacy influences second language reading acquisition through a transfer of skills; and (f) collaboration in the classroom supports learning by extending clients’ capabilities. These points form the basis of recommendations about how reading instruction might be improved for such clients.
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Responding to a series of articles in sport management literature calling for more diversity in terms of areas of interest or methods, this study warns against the danger of excessively fragmenting this field of research. The works of Kuhn (1962) and Pfeffer (1993) are taken as the basis of an argument that connects convergence with scientific strength. However, being aware of the large number of counterarguments directed at this line of reasoning, a new model of convergence, which focuses on clusters of research contributions with similar areas of interest, methods, and concepts, is proposed. The existence of these clusters is determined with the help of a bibliometric analysis of publications in three sport management journals. This examination determines that there are justified reasons to be concerned about the level of convergence in the field, pointing out to a reduced ability to create large clusters of contributions in similar areas of interest.
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Affiliation: Institut de recherche en immunologie et en cancérologie, Université de Montréal
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Ce triptyque d’essais présente le caractère versatile et évasif du concept moderne de capital social à plusieurs niveaux – global, national et régional, ainsi que dans le présent et dans le passé. Le premier article conteste l’hypothèse prédominante selon laquelle il y a une cohabitation entre l’engagement civique et la démocratie. Malgré sa validité au niveau général, la relation n’est pas confirmée si les catégories hétérogènes sont désagrégées. Pour les pays post-communistes de l'Europe, la relation entre le type de régime et la tendance de s'associer ressemble à celle des démocraties latines consolidées si la participation dans les associations volontaires est choisie comme mesure de la vitalité du capital social. Par conséquent, la vie civique moins intense ne prédit pas de difficultés pour la démocratie. Le deuxième article est une compilation originale de plus de 100 organisations classifiées selon les standards contemporains et une collection de présentations d'une douzaine d'organisations bulgares, les plus populaires depuis le XIXème siècle. Cette contribution importante à l’historiographie de la vie associative bulgare jusqu’à 1944 est le résultat d'un travail qui combine des entrevues avec des historiens et une recherche dans les archives. Le panoptique organisationnel sert de réfutation empirique de l’hypothèse qui attribue la faiblesse organisationnelle présente du poste-communisme à la pénurie de vie organisationnelle développée par le passé. ii Les mérites du troisième article sont doubles. Au niveau empirique on démontre que l’organisation culturelle la plus importante en Bulgarie a apparu comme une institution nationaliste imitant les organisations similaires des autres pays Européens. Elle s’est développée graduellement par une adaptation des expériences étrangères aux conditions locales. La collection des références bulgares est unique et représente le produit d’un travail méticuleux sur les documents et les entrevues. Au niveau abstrait, on confirme l’applicabilité de la théorie du transfert de la politique publique à un cas historique existant avant la théorie elle-même. Finalement, l’analyse détaillée des précurseurs du cabinet de lecture bulgare représente une contribution à la sociologie politique de l’histoire de la lecture. Mots clés: Europe de l’Est, poste-communisme, démocratie, société civile, engagement civique, organisations volontaires, troisième secteur, affiliation, transfert d'idées, apprentissage organisationnel.
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Objectives: This article further examines the phenomenon of aggression inside barrooms by relying on the “bouncer-ethnographer” methodology. The objective is to investigate variations in aggression through time and space according to the role and routine of the target in a Montreal barroom. Thus, it provides an examination of routine activity theory at the micro level: the barroom. Methods: For a period of 258 nights of observation in a Canadian barroom, bouncers completed reports on each intervention and provided specific information regarding what happened, when and where within the venue. In addition, the bouncer-ethnographer compiled field observations and interviews with bar personnel in order to identify aggression hotspots and “rush hours” for three types of actors within barrooms: (a) bouncers, (b) barmaids and (c) patrons. Findings: Three different patterns emerged for shifting hotspots of aggression depending on the target. As the night progresses, aggressive incidents between patrons, towards barmaids and towards bouncers have specific hotspots and rush hours influenced by the specific routine of the target inside the barroom. Implications: The current findings enrich those of previous work by pointing to the relevance of not only examining the environmental characteristics of the barroom, but also the role of the target of aggression. Crime opportunities follow routine activities, even within a specific location on a micro level. Routine activity theory is thus relevant in this context, because as actors in differing roles follow differing routines, as do their patterns of victimization.