499 resultados para Radiação eletromagnética


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As formações vegetais são altamente dinâmicas e dependem principalmente da taxa de crescimento das espécies vegetais, entretanto, esta está intimamente relacionada e suscetível a estresses abióticos, como elevada ou baixa radiação solar, temperaturas extremas, e bióticos, como taque de patógenos e de herbívoros, o que faz com que as plantas necessitem de um sistema de defesa altamente eficiente o qual consiste na atuação de compostos secundários, e de enzimas como por exemplo peroxidases e polifenoloxidases. A atividade das peroxidases constitui a mais importante via do sistema de defesa vegetal a patógenos no que se refere a cicatrização de ferimentos e à herbivoria, propiciando um aumento da lignificação nos tecidos lesados, o que aumenta a resistência dos mesmos, dificultando assim a ocorrência de novas lesões. Quanto às polifenoloxidases, também pertencentes ao grupo das oxidorredutases, são enzimas que também atuam diretamente na via de defesa das plantas ao ataque de patógenos e na cicatrização de ferimentos e processos de senescência. Por meio da extração e análise da atividade de Peroxidases e Polifenoloxidases em porção de raiz, caule, ápice e em folhas de indivíduos de Erythrina speciosa Andrews, Eugenia uniflora L., Hevea brasiliensis M. Arg., Hymenaea courbaril L. var. stilbocarpa (Hayne) Lee et Lang, Joannesia princeps Vell., Licania tomentosa (Benth.) Fritsch, Pachira aquatica Aubl. e Psidium guajava L., obteve-se comportamento pioneiro para as espécies Eugenia uniflora L., Hymenaea courbaril L. var. stilbocarpa (Hayne) Lee et Lang, Joannesia princeps Vell. e Psidium guajava L., e comportamento não-pioneiro para as espécies Erythrina speciosa Andrews, Hevea brasiliensis M. Arg., Licania tomentosa (Benth.) Fritsch e Pachira aquatica Aubl.. Dessa maneira foi possível verificar que a análise da atividade peroxidásica... (Resumo completo, clicar acesso eletrônico abaixo)

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Radiotherapy in veterinary practice is already known and widely distributed in large specialized centers of developed countries. In early 2000, there were about 30 radiotherapy equipment specifically designed for the veterinary clinic in the United States. In Brazil, the veterinary radiotherapy is still confined to research in universities, where most of the procedures is radiation therapy performed with superficial x-ray machines, with a voltage between 50 and 150 kVp, focus-distance surface (DFS) between 20,0cm and 40,0cm. As that occurs in human medicine, new research strengthens the development and prospects for the use of radiotherapy as a safe option for treating cancer in animals. This paper presents a methodology for calculating the exposure time for superficial radiotherapy procedures in veterinary medicine for small animals (dogs and cats). The dosimetric parameters of X-rays are determined using a spreadsheet tool for Microsoft Office Excel, developed in this paper for a device Dermopan 2, Veterinary Hospital of UNESP in Araçatuba. Using the worksheet helps the veterinarian to determine the time of exposure to radiation determined for each clinical case, optimize the workflow for professionals in veterinary radiotherapy procedures, which often lack the medical physics in team and at the time of radiotherapy. The correct use of spreadsheet decreases the chances of errors in dose rates of radiation, providing a higher quality of care

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The sources of betatherapy for clinical use in Brazil are, the vast majority of strontium-90, radioactive element that is not produced in the country, and therefore requires importation of international laboratories accredited by the International Atomic Energy Agency (IAEA).The use of these resources is always limited the crediting of characteristic values supplied by the manufacturer tables that provide the nominal value of activity and dose distribution to determine the irradiation time of the injury. The Institute of Nuclear Energy Research (IPEN / CNEN-SP) has recently researching the emission profile of these types of radiation sources, and some jobs are being developed with ionization chambers extrapolation for the purpose of standardizing a systematic calibration sources betatherapy. Other studies using parallel measures dosimeters (TLD's) and simulations with the Monte Carlo method. Radiological films have also been used in studies of applicators dosimetric analysis of strontium-90. This paper seeks to analyze the different methods for calibration of applicators betatherapy, already consolidated in studies by examining the advantages and disadvantages of each procedure

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After the discovery of ionizing radiation, its applications in various fields of science began to take significant proportions. In the case of medicine, there are the application areas in radiotherapy, diagnostic radiology and nuclear medicine. It was then necessary to create the field of radiological protection to establish the conditions necessary for the safe use of such ionizing radiation. Apply knowledge obtained during the graduation stage and in the practice of radiological protection in the areas of nuclear medicine and diagnostic radiology. In the area of nuclear medicine, tests were made in the Geiger-Muller counters (GM) and the dose calibrator (curiometer), the monitoring tests of radiation, waste management, clean of the Therapeutic room and testing the quality control of gamma-chambers. In the area of radiology, were performed tests of quality control equipment for conventional X-ray equipment and x-ray fluoroscopy, all following the rules of the National Health Surveillance Agency (ANVISA), and reporting of tests. The routine developed in the fields of nuclear medicine in hospitals has proved very useful, since the quality control of GM counters contribute to the values of possible contamination are more reliable. The control of dose calibrator enables the patient not to receive different doses of the recommended amounts, which prevents the repetition of tests and unnecessary exposure to radiation. The management of waste following the rules and laws established and required for its management. Tests for quality control of gamma chambers help to evaluate its medical performance through image. In part of diagnostic radiology, tests for quality control are performed in order to verify that the equipment is acceptable for usage or if repairs are needed. The knowledge acquired at the internship consolidated the learning of graduation course

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As plantas apresentam moléculas que detectam a luz, entre elas estão os fitocromos que detectam mudanças na qualidade da luz nas regiões de vermelho (V) e vermelho-extremo (VE). O fitocromo age no crescimento das plantas possibilitando-as perceber o sombreamento por outras plantas, o que pode ocasionar no processo de estiolamento, ou seja, alongamento do caule. Assim, conforme aumenta o sombreamento, a razão V:VE diminui. Nas plantas de sol, quanto maior a proporção de VE, maior a taxa de estiolamento, enquanto que as plantas de sombra mostram pouca ou nenhuma redução na taxa de alongamento dos caules. Na sucessão florestal as plantas podem ser classificadas como pioneiras, sendo aquelas dependentes de luz e intolerantes à sombra, e as de transição ou clímax, que são tolerantes à sombra. Assim, este trabalho teve o intuito de analisar o processo de estiolamento de plântulas de espécies arbóreas nativas selecionadas, mantidas em condições de luz diferentes e correlacionar com a classe seral correspondente citada na literatura. As seguintes espécies foram analisadas: Bixa orellana, Caesalpinia peltophoroides, Dalbergia nigra, Erythrina speciosa, Eugenia uniflora, Hevea brasiliensis, Hymenaea courbaril, Licania tomentosa, Pachira aquatica, Piptadenia gonoacantha, Psidium guajava, Schizolobium parahyba. Todos os experimentos foram desenvolvidos no jardim experimental da UNESP de Rio Claro. As espécies foram expostas a seis condições luminosas diferentes, com razão V:VE de: 0,1; 0,19; 0,21; 0,35; 1,15 e 1,17. E radiação solar incidente de: 3,16UM; 44,78UM; 27,7UM; 73,54UM; 1987,00UM; 1453,00UM. Foram tiradas medidas do comprimento dos hipocótilos e epicótilos. Posteriormente foram realizadas análises estatísticas com nível de significância de 5%. As espécies consideradas pioneiras foram D. nigra e S. parahyba. E as espécies classificadas como não pioneiras foram:... (Resumo completo, clicar acesso eletrônico abaixo)

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Pós-graduação em Biociências - FCLAS

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Pós-graduação em Cirurgia Veterinária - FCAV

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Pós-graduação em Agronomia (Ciência do Solo) - FCAV

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The teaching of modern and contemporary Physics subjects in high school is indispensable and it was already justified by several researchers. Among the subjects which must be taught, there is, for instance, Bohr atomics model. However, as it was noticed in literature review, many didactic materials do not deal with this model adequately, since that they do not take into account Bohr ideas, which involved Planck studies on black-body radiation, Einsten theory for photoelectric effect, Rutherford experiences and atomics model and the empiric results upon the spectrums of chemical elements emission. From that, it is extremely important teaching through approaches which potentialize the learning of the model proposed by Niels Bohr. On the other hand, teachers from high schools cannot have clearness about which approaches can be applied for teaching the mentioned model. Thus, it is presented some possibilities for teaching Bohr atomics model, with examples and justifications for the use of each one. Special treatment was attributed to the teaching from Science History and Philosophy, from the reading of scientific diffusion and original scientific texts, from analogies, from comic strips and from computer simulations.

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This paper consists in the evaluation of the exposure rate to ionizing radiation to which professionals working in surgical procedures which require radiological examinations are subjected. Were initially performed real-time readings of exposure rate within four distinct operating rooms during the execution of four surgical procedures that made use of fluoroscopy equipment (including three orthopedic surgeries, one in the shoulder, one in the arm, another for deployment of metal pin in the leg region, and a fourth for vascular procedure); in these surgeries were used ionization chamber detector and an electrometer. In order to check the values achieved, was made a re-evaluation of the distribution of the rate of exposure to radiation, from the surgical procedures, now with thermoluminescent dosimeters (TLDs). For this, thirty TLDs were distributed in the operating rooms, arranged in points of interest as occupation by professionals. The TLDs were prepared for thirty consecutive days, after which they were removed and replaced with new dosimeters not exposed yet. The dosimeters were subjected to reading of the rate of exposure; this procedure was repeated for four months without interruption. The quantification of the results sought primarily to convert the rate of exposure for equivalent dose rate, both in measurements with ionization chamber as in measurements with TLDs, in order to highlight the presence of the biological effect of ionizing radiation for comparisons within scientific context. Then, the results were plotted to establish the relationship between the values of equivalent dose and the distance to the central axis of the x -ray source, confirming the inverse square law for distance. Finally, the values were associated with the maximum limit recommended by the legislation for occupationally exposed individuals. The methodology for the analysis and quantification of the data in this work aims at implementing a work plan that meets ...

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This graduation work done study of polyamide 6.6/composite carbon fibres, since its processing, characterization of the main properties. Besides the influence of temperature, UV radiation, salt spray and moisture on the mechanical and viscoelastic behavior. To achieve this goal, the first composite was processed from the heat compression molding using known variables of the process and using the empirical method to find the best value for other parameters. The method processing molding was chosen because it common in composites processing in order to evaluate the influence of crystallinity of the properties that influence the mechanical and viscoelastic behavior laminates. From the obtained laminate specimens were evaluated in weathering, such as: in hygrothermal chamber, UV, salt spray and thermal shock. In another step, the effect produced by these constraints were evaluated by optical microscopy, ultrasound, dynamic mechanical analysis and vibration tests. This project was conducted at the Department of Technology and Materials of UNESP in Guaratingueta, where all the equipment and techniques for the implementation of this project met available. After the tests proved the applicability of the composite polyamide 6.6/carbon fibers in aeronautical applications with resistance the main climatic influences