A abordagem de alguns números irracionais notáveis nos livros didáticos do ensino fundamental e médio

Este texto descreve os resultados de uma pesquisa orientada pela questão ‘Como são abordados os números irracionais no ensino básico, considerando-se como fonte o livro didático?’. Em uma amostra de livros didáticos, observamos se e como são apresentados ‘o número PI’, ‘o número de Euler’ e ‘o número de Ouro’. A investigação utilizou os núcleos de significação para analisar os sentidos do discurso presente nos textos dos livros didáticos. Constatamos que os temas apontados são introduzidos por um viés empírico ou pela definição formal, porém não ocorre intercâmbio destes pólos. Observamos que o número PI é empiricamente abordado, o número de Euler é apenas citado como uma possível base dos logaritmos e fica destaca a interface artística do número de Ouro articulada a representação algébrica. Em síntese, esta opção dos livros didáticos reforça uma concepção tecnicista, limitando a compreensão da complexidade dos números irracionais no Ensino Fundamental e Médio.Palavras-chave: Livro Didático. Núcleos de Significação. Número PI. Número de Euler. Número de Ouro

Low Energy Singlets in the Excitation Spectrum of the Spin Tetrahedra System Cu_2Te_2O_5Br_2

Low energy Raman scattering of the s=1/2 spin tetrahedra system Cu_2Te_2O_5Br_2 is dominated by an excitation at 18 cm^{-1} corresponding to an energy E_S=0.6\Delta, with \Delta the spin gap of the compound. For elevated temperatures this mode shows a soft mode-like decrease in energy pointing to an instability of the system. The isostructural reference system Cu_2Te_2O_5Cl_2 with a presumably larger inter-tetrahedra coupling does not show such a low energy mode. Instead its excitation spectrum and thermodynamic properties are compatible with long range Neel-ordering. We discuss the observed effects in the context of quantum fluctuations and competing ground states.Comment: 5 pages, 2 figures, ISSP-Kashiwa 2001, Conference on Correlated Electron

Genealogia de variedades IAC de cana-de-açúcar: vulnerabilidade genética e necessidade de programas básicos de melhoramento

The study of the pedigree of 23 IAC sugarcane varieties lead to the conclusion that only 3 species contributed to their formation: Saccharum officinarum, S. spontaneum and S. barberi. Co290 and POJ2878 were the outstanding varieties, being the ancestors of most IAC varieties, which caused a narrowed genetic base and therefore a genetic vulnerability to pests and diseases. The stablishment of a basic or broadening genetic program is discussed.Através do estudo da genealogia de 23 variedades IAC de cana-de-açúcar, chegou-se à conclusão de que apenas três espécies contribuíram para sua formação: Saccharum officinarum, S. spontaneum e S. barberi. A maioria delas descende, direta ou indiretamente, de duas variedades principais, Co290 e POJ2878, o que leva a um estreitamento da base genética e consequente vulnerabilidade a pragas e moléstias. Discute-se, em vista disso, a viabilidade e a necessidade do estabelecimento de programa básico de melhoramento

Changes in trabecular bone, hematopoiesis and bone marrow vessels in aplastic anemia, primary osteoporosis, and old age

Retrospective histologic analyses of bone biopsies and of post mortem samples from normal persons of different age groups, and of bone biopsies of age- and sex-matched groups of patients with primary osteoporosis and aplastic anemia show characteristic age dependent as well as pathologic changes including atrophy of osseous trabeculae and of hematopoiesis, and changes in the sinusoidal and arterial capillary compartments. These results indicate the possible role of a microvascular defect in the pathogenesis of osteoporosis and aplastic anemia

Technical Note: In silico and experimental evaluation of two leaf-fitting algorithms for MLC tracking based on exposure error and plan complexity.

PURPOSE: Multileaf collimator (MLC) tracking is being clinically pioneered to continuously compensate for thoracic and pelvic motion during radiotherapy. The purpose of this work was to characterize the performance of two MLC leaf-fitting algorithms, direct optimization and piecewise optimization, for real-time motion compensation with different plan complexity and tumor trajectories. METHODS: To test the algorithms, both in silico and phantom experiments were performed. The phantom experiments were performed on a Trilogy Varian linac and a HexaMotion programmable motion platform. High and low modulation VMAT plans for lung and prostate cancer cases were used along with eight patient-measured organ-specific trajectories. For both MLC leaf-fitting algorithms, the plans were run with their corresponding patient trajectories. To compare algorithms, the average exposure errors, i.e., the difference in shape between ideal and fitted MLC leaves by the algorithm, plan complexity and system latency of each experiment were calculated. RESULTS: Comparison of exposure errors for the in silico and phantom experiments showed minor differences between the two algorithms. The average exposure errors for in silico experiments with low/high plan complexity were 0.66/0.88 cm2 for direct optimization and 0.66/0.88 cm2 for piecewise optimization, respectively. The average exposure errors for the phantom experiments with low/high plan complexity were 0.73/1.02 cm2 for direct and 0.73/1.02 cm2 for piecewise optimization, respectively. The measured latency for the direct optimization was 226 ± 10 ms and for the piecewise algorithm was 228 ± 10 ms. In silico and phantom exposure errors quantified for each treatment plan demonstrated that the exposure errors from the high plan complexity (0.96 cm2 mean, 2.88 cm2 95% percentile) were all significantly different from the low plan complexity (0.70 cm2 mean, 2.18 cm2 95% percentile) (P < 0.001, two-tailed, Mann-Whitney statistical test). CONCLUSIONS: The comparison between the two leaf-fitting algorithms demonstrated no significant differences in exposure errors, neither in silico nor with phantom experiments. This study revealed that plan complexity impacts the overall exposure errors significantly more than the difference between the algorithms

Satisfaction With Psychology Training In the Veterans Healthcare Administration

Given that VA is the largest trainer of psychologists in the United States, this study sought to understand satisfaction with VA psychology training and which elements of training best predict trainees\u27 positive perceptions of training (e.g., willingness to choose training experience again, stated intentions to work in VA). Psychology trainees completed the Learners\u27 Perceptions Survey (LPS) from 2005 to 2017 (N = 5,342). Satisfaction was uniformly high. Trainee satisfaction was significantly associated with level of training, facility complexity, and some patient-mix factors. Learning environment (autonomy, time with patients, etc.), clinical faculty/preceptors (teaching ability, accessibility, etc.), and personal experiences (work/life balance, personal responsibility for patient care, etc.) were the biggest drivers of stated willingness to repeat training experiences in VA and seek employment there. Results have implications for psychologists involved in the provision of a training experience valued by trainees

Эксплуатация подогревателей высокого давления на Томской ТЭЦ - 3

We report on the epitaxial growth of magnetoresistive La0.7Ca0.3MnO3 and La0.7Sr0.3MnO3 thin films by chemical solution deposition. Thin films were prepared by spin-coating of single-crystal LaAlO3 (100) substrates with precursor solutions of different concentrations and crystallized at 850 degrees C. The structure of the thin film was found to be influenced by the concentration of the spin-coating solution. The thin film structure and epitaxy was clearly improved by reducing the concentration of the precursor solution. All thin films displayed excellent electrical properties such as a low resistivity and very high metal-insulator transition temperatures T-MI

Green Production of Anionic Surfactant Obtained from Pea Protein

A pea protein isolate was hydrolyzed by a double enzyme treatment method in order to obtain short peptide sequences used as raw materials to produce lipopeptides-based surfactants. Pea protein hydrolysates were prepared using the combination of Alcalase and Flavourzyme. The influence of the process variables was studied to optimize the proteolytic degradation to high degrees of hydrolysis. The average peptide chain lengths were obtained at 3–5 amino acid units after a hydrolysis of 30 min with the mixture of enzymes. Then, N-acylation in water, in presence of acid chloride (C12 and C16), carried out with a conversion rate of amine functions of 90%, allowed to obtain anionic surfactant mixtures (lipopeptides and sodium fatty acids). These two steps were performed in water, in continuous and did not generate any waste. This process was therefore in line with green chemistry principles. The surface activities (CMC, foaming and emulsifying properties) of these mixtures were also studied. These formulations obtained from natural renewable resources and the reactions done under environmental respect, could replace petrochemical based surfactants for some applications

Assessment of information resources for people with hypodontia

Aim: To assess the adequacy of patient information to support understanding and decision-making for people affected by hypodontia. Methods: 1) Questionnaire to understand the provision of patient information by dentists; 2) Systematic search to identify online open-access patient information; 3) Quality assessment of written patient information. Results: Questionnaire response rate was 49% (319/649); 91% examined and/or treated people with hypodontia. Most general dentists referred patients to specialist services without providing written hypodontia information. The majority of dental specialists provide patient leaflets but less than a third used web-resources. Only 19% of respondents felt current resources were fit-for-purpose. Thirty-one patient resources (18 leaflets and 13 online) were assessed against quality criteria. The aim of the resource was seldom explicit, the content was often incomplete and variation in readability scores indicated high levels of literacy were required. Discussion: Access to, and quality of, patient information for hypodontia is inadequate. Current resources are not sufficiently comprehensive to prepare young patients to engage in shared dental care decisions with their parents and/or dental professionals. Conclusion: There is a need for improved access to, and provision of, information about hypodontia if dental professionals want to meet best practice guidance and involve patients in shared decision-making

Effect of a freeze on some technological characteristics of several sugar cane varieties

Em 18 de julho de 1975, ocorreu geada no Estado de São Paulo; em Piracicaba, a temperatura atingiu -1ºC. Aproveitou-se a ocorrência da geada para investigar seus efeitos sobre características tecnológicas de algumas variedades. Foram tomadas amostras de dez colmos cada uma, a partir de doze dias após a geada, e depois, aproximadamente, a cada duas semanas. Analisaram-se brix % caldo, pol % caldo e, por inferência, produção de açúcar provável (em kg/t de cana). Dadas as condições do meio ambiente e das próprias plantas, pode-se dizer que estas não sofreram alterações dignas de nota nas sete amostras quinzenais efetuadas após a geada, nas características analisadas. Aplicando-se análise de regressão, verificou-se que os dados de brix % caldo ajustaram-se melhor às curvas de 2º grau. O teste F para regressão foi significativo em nove dos quinze casos estudados.A freeze occurred in the State of São Paulo, on July, 18th, 1975 with the temperature decreasing to -1ºC in Piracicaba. Advantage was taken of this occurrence to study the effect of freeze on the technological characteristics of some commercial sugar cane varieties. Ten stalk samples were taken for the experiment, beginning at twelve days after the freeze and thereafter every two weeks. Brix % juice, pol % juice and, by inference, theoretical sugar yield (kg/t of cane) were studied. Due to the environmental and plant conditions in the field, it could be concluded that the varieties did not show significant alterations caused by the freeze in none of the seven fortnight samples. Regression analysis showed that brix % juice data fitted 2nd degree curves better than the other data, with F test significant in nine out of fifteen cases