4,070 research outputs found
Sequências de ensino aprendizagem e os ciclos de reflexão na preparação docente para a parceria escola-centro de ciências
Este trabalho aborda aspectos da cultura escolar e de centros de ciências na perspectiva da transformação de saberes que utilizam a física solar para discutir física moderna no ensino médio. O centro de ciências em questão é o Observatório Dietrich Schiel da Universidade de São Paulo. Refletimos sobre a preparação didático-pedagógica realizada com quatro professores de ensino médio envolvidos na pesquisa. Os trabalhos foram guiados a partir da ferramenta metodológica chamada de «Ciclos de Reflexão», desenvolvida pelo nosso grupo de pesquisa. Os resultados evidenciam que os professores participantes interpretam os centros de ciências como locais de aprendizagem, e que suas preocupações em ensinar física moderna giram em torno do «Como ensinar», «O que ensinar» e do «Tempo disponível» dentro dos apertados currículos de física do ensino médio público brasileiro
Resultados oncológicos da nefrectomia radical laparoscópica no tratamento do carcinoma renal
PURPOSE: To report the 5-year oncological outcomes of patients undergoing laparoscopic radical nephrectomy for renal cancer compared to a cohort of patients undergoing open radical nephrectomy. METHODS: We retrospectively analyzed the data of 88 patients undergoing radical nephrectomy for renal cell carcinoma prior to January 2000. Of these, 45 patients underwent laparoscopic radical nephrectomy, and 43 patients underwent open radical nephrectomy. Inclusion criteria comprised clinically organ-confined tumors of 15 cm or less in size without concomitant lymphadenopathy or vena cava thrombus. Oncological follow-up data were obtained from charts, radiological reports, and phone calls to patients or their families, and were calculated from the date of surgery to the date of last appointment with physician or date of death. RESULTS: All laparoscopic procedures were completed without open conversion. On comparing the laparoscopic radical nephrectomy and open radical nephrectomy groups, mean tumor size was 5. 8 vs 6.2 cm (P = . 44), mean blood loss was 183 vs 461 mL (P = . 004), and mean operative time was 2.8 vs 3.7 hrs (P < . 001). Over a mean follow-up of 5 years in the laparoscopic radical nephrectomy group and 6 years in the open radical nephrectomy group, the overall survival was 81% vs 79% (P = . 47), and cancer-specific survival was 90% vs 92% (P = . 70) , respectively. CONCLUSIONS: Laparoscopic radical nephrectomy for renal cancer confers equivalent 5-year oncological outcomes to those of open surgery.OBJETIVO: Relatar os resultados oncológicos após 5 anos de seguimento em pacientes submetidos a nefrectomia radical laparoscópica para tratamento do câncer renal, comparando esses com os resultados obtidos com um grupo de pacientes submetidos a nefrectomia radical aberta. MÉTODOS: Foram analisadas retrospectivamente as informações obtidas de 88 pacientes submetidos a nefrectomia radical para o tratamento do carcinoma renal realizadas previamente a Janeiro de 2000. Destes pacientes, 45 foram tratados com nefrectomia radical laparoscópica e 43 com nefrectomia radical aberta. Foram incluídos pacientes com tumores localizados com tamanho máximo de 15 cm, sem adenopatia ou sinal de envolvimento de veia renal na avaliação radiologica pré-operatória. As informações sobre o seguimento dos pacientes foram obtidas a partir de prontuários, laudos de exames radiológicos e ligações telefônicas para pacientes e/ou familiares. O seguimento foi calculado desde a data da cirurgia até a última consulta médica ou data de falecimento. RESULTADOS: Todos os procedimentos laparoscópicos foram realizados sem conversão para a técnica aberta. O tamanho médio tumoral foi de 5.8 e. 6.2 cm (P=0.44), perda sanguínea estimada de 183 e. 461 mL (P=0.004), e tempo operatório de 2.8 e. 3.7 horas (
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Detecting compositional changes in dielectric materials simulated by three-dimensional RC network models
This work discusses the detection of small compositional changes in materials that have microstructures containing conducting and dielectric phases, which can be described by networks of resistive (R) and capacitive (C) components in a three-dimensional lattice. For this purpose, a principal component analysis (PCA) method is employed to discriminate normal samples from samples with altered composition on the basis of statistics extracted from the waveform of the network response to a given excitation. This approach obviates the requirement for multivariate regression and simplifies experimental workload for model-building, since only data from normal samples are required in the development of the PCA model. Waveform variability of the excitation source is also accounted for through the use of a nominal model derived using subspace identification. This enables standardization and software based metrology transfer across different labs. The effect of network size on the capability of detecting minute compositional changes was assessed. For networks of 520 components, it was possible to identify changes in the fraction of capacitors down to 10-2 at 2 sigma confidence levels
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Fixation of aqueous tritiated waste in polymer impregnated concrete and in polyacetylene
Tritiated aqueous waste can be used to hydrate hydraulic cement producing a concrete that contains a network of interconnected porosity. Such a product is subject to water intrusion and subsequent tritium loss by leaching and exchange. Techniques have been developed to impregnate this porosity with styrene monomer which is then polymerized in situ, resulting in a concrete that is essentially impermeable while its strength, durability, and resistance to chemical attack are significantly improved. Tritium bulk leach rates as low as 1.68 x 10 g/(cm-day) have been measured for polymer-impregnated concrete in water. An adsorbent additive can be incorporated to increase the specific tritiated waste loading of the concrete. Depending upon the formulations, these composites incorporate 5.8 to 8.3 liters HTO per cubic foot. Tritiated aqueous waste can also be fixed in polymeric form as polyacetylene through reaction with calcium carbide to form tritiated acetylene which is subsequently polymerized. Acetylene polymerization is accomplished by either Co gamma irradiation or thermal catalysis over cupric oxide. The tritiated polyacetylene produced can contain up to 50 atomic percent tritium and is essentially non-leachable, insoluble, thermally stable to 325C, and chemically inert. The bulk leach rate of tritiated polyacetylene was determined to be of the order of 1.8 x 10 g/(cm-day). Radiolysis by Co gamma irradiation results in a G value for hydrogen production of 0.15 molecules/100 eV. Tritiated polyacetylene can be incorporated as an aggregate in concrete, polymer concrete, or polymer impregnated concrete to form a monolithic solid. (auth
A percepção da gravidade na ‘Casa Maluca’ do CDCC/USP: UMA análise a luz de Gaston Bachelard
Esta pesquisa teve como objetivo entender como um espaço fisicamente alterado influencia as percepções e explicações acerca da gravidade pelos estudantes do ensino médio. A pesquisa foi realizada na Casa Maluca do CDCC/USP. Esta é uma casa com piso e paredes inclinados com ângulos de 15 graus em relação ao referencial externo, ao entrar em seu interior os visitantes experimentam alterações na percepção de alguns fenômenos do cotidiano relacionados com a força da gravidade. Tomamos como referencial teórico principal a noção de obstáculos epistemológicos propostos por Gaston Bachelard e metodologia de pesquisa quantitativa e qualitativa. Os resultados nos revela a presença de alguns obstáculos epistemológicos, tais como: experiência primeira, realismo ingênuo, substancialismo, animismo e obstáculo verbal na argumentação dos alunos no entendimento do conceito gravidade. Demonstram também a dificuldade dos alunos em entender o conceito gravidade e seu caráter vetorial
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Solidification of oils and organic liquids
The suitability of selected solidification media for application in the disposal of low-level oil and other organic liquid wastes has been investigated. In the past, these low-level wastes (LLWs) have commonly been immobilized by sorption onto solid absorbents such as vermiculite or diatomaceous earth. Evolving regulations regarding the disposal of these materials encourage solidification. Solidification media which were studied include Portland type I cement; vermiculite plus Portland type I cement; Nuclear Technology Corporation's Nutek 380-cement process; emulsifier, Portland type I cement-sodium silicate; Delaware Custom Materiel's cement process; and the US Gypsum Company's Envirostone process. Waste forms have been evaluated as to their ability to reliably produce free standing monolithic solids which are homogeneous (macroscopically), contain < 1% free standing liquids by volume and pass a water immersion test. Solidified waste form specimens were also subjected to vibratory shock testing and flame testing. Simulated oil wastes can be solidified to acceptable solid specimens having volumetric waste loadings of less than 40 volume-%. However, simulated organic liquid wastes could not be solidified into acceptable waste forms above a volumetric loading factor of about 10 volume-% using the solidification agents studied
Outcomes of flexible ureteroscopic lithotripsy with holmium laser for upper urinary tract calculi
OBJECTIVE: To assess the perioperative and financial outcomes of flexible ureteroscopic lithotripsy with holmium laser for upper tract calculi in 44 patients. MATERIALS AND METHODS: Between February 2004 and September 2006, 44 patients treated for upper tract stone with flexible ureteroscopic lithotripsy were evaluated. Renal stones were associated with collecting system obstruction in 15 (34%) patients, failed extracorporeal shock-wave lithotripsy (SWL) occurred in 14 (32%) patients, unilateral multiple stones in 18 (41%) patients, and multiple bilateral stones in 3 (7%). In 29 (66%) patients, the stone was located in the inferior calyx. Perioperative and financial outcomes were also evaluated. RESULTS: 50 procedures were performed in 44 patients. The mean stone burden on preoperative CT scan was 11.5 ± 5.8 mm. The mean operative time was 61.3 ± 29.4 min. The stone free rate was 93.1% after one procedure and 97.7% after a second procedure, with overall complication rate of 8%. Therapeutic success occurred in 92% and 93% of patients with lower pole stones and SWL failure, respectively. Treatment failure of a single session was associated with presence of a stone size larger than 15 mm (p = 0.007), but not associated with inferior calyx location (p = 0.09). Surgical disposables were responsible for 78% of overall costs. CONCLUSION: Flexible ureteroscopy using holmium laser is a safe and effective option for the treatment of upper urinary tract calculi. In addition, it can be considered an attractive option as salvage therapy after SWL failure or kidney calculi associated with ureteral stones. Stone size larger than 15 mm is associated with single session treatment failure
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