Pedagogia Freinet: a construção de uma práxis em turmas de 5ª a 8ª séries

Ce travail que nous venons de présenter apport une systématisation sur la viabilité de la praxis de l´éducateur français Célestin Freinet (1896-1996). Il s´agit d´une étude qualificative, recherche-action, développée dans une école coopérative l´ École Freinet à Natal/RN Brésil, auprès des élèves du 5ème et 8ème séries de l´Enseignement Fondamental. Le problème central que nous a amené à cette recherche, a été le fait de vérifier les progressions dans la production scientifique et dans les pratiques des enseignants qui ont à la charge l´Éducation Infantine et les premières séries de l´Enseignement Fondamental. Tout cela en tenant compte en concevoir l´élève en tant que sujet actif de son apprentissage et coresponsable à l´organisation du travail scolaire. Toutefois, qaund-il s´agit des quatre dernières séries de l´Enseignement Fondamental (5ème au 8ème séries), les propositions progressistes sont prises comme quelque chose pratiquement impossible d´en mettre en marche. Pour attenuer la lacune théorique sur le sujet, nous avons offert un texte significatif pour les enseignants d´une façon générale, les chercheurs de l´académie et pour l´écolechamp de la recherché. Tout cela par le fait de ne pas donner de priorité à une technique ou à un principe, en particulier. Cette pédagogie est discutée autant que possible dans son contexte global et aussi sur le comment s´est manifestée dans sa práxis . Nous avons mis en relief les aspects importants pour le fonctionnement de la salle de classe, aussi que les estratégies utilisées pour la construction, communication et documentation des connaissances L´intervention nous a permis de construire l´objet par la réflexion en action, à partir des données obtenues pendant les observations, les entretiens, les enterviews, les moments d´études et de la quête des textes écrits. L´analyse a été faite à la lumière de la methodologie comprehensive (Kaufmann, 1996), entrelacée au materiau empirique et à la théorie. Cette forme d´analyse nous a permis d´obtenir la logique dans l´ensemble comme nous crayons que doit caracteriser la recherche aux Sciences Humaines et Sociales. Les considérations finales mettent l´accent d´un côté sur l´efficacité de la pédagogie Freinet, pour orienter le processus de l´enseignement apprentissage, en tous les dégres de l´enseignement et de l´autre côté nous montre la nécessité urgente de l´équipe de l´école champ de la recherche, de qualifier sa pratique à partir des références théoriques-pratiques de la pédagogie Freinet

Controle químico da tiririca (Cyperus rotundus), com e sem cobertura do solo pela palha de cana-de-açúcar

Objetivou-se neste trabalho avaliar a eficácia e seletividade da mistura comercial pronta de trifloxysulfuron-sodium + ametryne (1.312,5 e 1.500 g ha-1), em comparação ao halosulfuron (112,5 g ha-1), MSMA (2.400 g ha-1), 2,4-D (1.675 g ha-1), sulfentrazone (700 g ha-1) e imazapic (105 g ha-1), além das testemunhas infestada e capinada, no controle de tiririca (Cyperus rotundus) em um canavial, com e sem cobertura do solo com a palhada da cana remanescente da colheita. A palhada de cana reduziu a infestação, porém não evitou grandes densidades das plantas de tiririca. O número de tubérculos inviáveis foi superior a 50% nas áreas onde se aplicou a mistura pronta (1.312,5 e 1.500 g ha-1), apesar do controle apenas regular (41,3 a 67,5%) das manifestações epígeas. Os melhores resultados de controle foram proporcionados pelos herbicidas sulfentrazone (700 g ha-1) e imazapic (105 g ha-1), sem a cobertura de palha. O número de afilhos, a altura das plantas e a produção de colmos foram reduzidos apenas na testemunha infestada e onde se aplicaram os herbicidas 2,4-D (1.675 g ha-1) e MSMA (2.400 g ha-1), que proporcionaram os menores níveis de controle. Os herbicidas foram seletivos para as plantas de cana-de-açúcar da variedade RB806043.

Activation and early parthenogenesis of bovine oocytes treated with ethanol and strontium

Efficient artificial activation is indispensable for the success of cloning programs. Strontium has been shown to effectively activate mouse oocytes for nuclear transfer procedures, however, there is limited information on its use for bovine oocytes. The present study had as objectives: (1) to assess the ability of strontium to induce activation and parthenogenetic development in bovine oocytes of different maturational ages in comparison with ethanol; and (2) to verify whether the combination of both treatments improves activation and parthenogenetic development rates. Bovine oocytes were in vitro matured for 24, 26, 28, and 30 h, and treated with ethanol (E, 7% for 5 min) or strontium chloride (S, 10 mM SrCl2 for 5 h) alone or in combination: ethanol + strontium (ES) and strontium + ethanol (SE). Activated oocytes were cultured in vitro in synthetic oviductal fluid (SOF) medium and assessed for pronuclear formation (15-16 h), cleavage (46-48 h) and development to the blastocyst stage (M). Treatment with ethanol and strontium promoted similar results regarding pronuclear formation (E, 20-66.7%; S, 26.7-53.3%; P > 0.05) and cleavage (E, 12.8-40.6%; S, 16.1-41.9%; P > 0.05), regardless of oocyte age. The actions of both strontium and ethanol were influenced by oocyte age: ethanol induced greater activation rates after 28 and 30 h of maturation (48.4 and 66.7% versus 20.0 and 23.3% for 24 and 26 It, respectively; P < 0.05) and strontium after 30 It (53.3%) was superior to 24 and 26h (26.7% for both). Blastocyst development rates were minimal in all treatments (0.0-6.3%; P > 0.05), however, when the mean (+/-S.D.) cell number in blastocysts at the same maturational period was compared, strontium treatment was superior to ethanol for activation rates (82 +/- 5.7 and 89.5 +/- 7.8 versus 54 and 61, at 28 and 30 h, respectively). Improved results were obtained by combined treatments. The combination of ethanol and strontium resulted in similar pronuclear formation (ES, 36.7-83.9%; SE, 53.1-90.3%) and cleavage rates (ES, 31.3-81.3%; SE, 65.6-80.7%). Regarding embryo development, there was no difference (P > 0.05) between treatments, and blastocysts were only obtained in treatment SE at 24 and 26 h (6.5% for both). It is concluded that, SrCl2 induces activation and parthenogenetic development in bovine oocytes. (C) 2003 Elsevier B.V. All rights reserved.

Sexing of murine and bovine embryos by developmental high-titer arrest induced by H-Y antisera

Murine and bovine embryos at the late morula stage were cultured in medium containing high-titer rat H-Y antisera. After 12 h of incubation, embryos blocked at the late morulae stage were classified as males and those at the blastocyst stage were classified as females. Sexing of murine embryos by PCR and cytogenetics revealed that 83% of the embryos classified as males and 82% of those classified as females had their sex correctly predicted (P < 0.05). Bovine embryos were transferred to recipient females. Pregnancy rates were 71.4% (10/14) for embryos classified as males and 68.8% (11/16) for embryos classified as females. The sex was correctly predicted for 80% (8/10) of the embryos classified as males and for 81.8% (9/11) of those classified as females (overall accuracy, 80.9%, P < 0.05). Therefore, the induction of developmental arrest by high-titer male-specific antisera was an efficient strategy for non-invasive embryo sexing. The procedure was straightforward and has considerable commercial potential for sexing bovine embryos. (c) 2004 Elsevier B.V. All rights reserved.

Nucleus isthmi and control of breathing in amphibians

Despite recent advances, the mechanisms of neurorespiratory control in amphibians are far from understood. One of the brainstem structures believed to play a key role in the ventilatory control of anuran amphibians is the nucleus isthmi (NI). This nucleus is a mesencephalic structure located between the roof of the midbrain and the cerebellum, which differentiates during metamorphosis; the period when pulmonary ventilation develops in bullfrogs. It has been recently suggested that the NI acts to inhibit hypoxic and hypercarbic drives in breathing by restricting increases in tidal volume. This data is similar to the influence of two pontine structures of mammals, the locus coeruleus and the nucleus raphe magnus. The putative mediators for this response are glutamate and nitric oxide. Microinjection of kynurenic acid (an ionotropic receptor antagonist of excitatory amino acids) and L-NAME (a non-selective NO synthase inhibitor) elicited increases in the ventilatory response to hypoxia and hypercarbia. This article reviews the available data on the role of the NI in the control of ventilation in amphibians. (C) 2004 Elsevier B.V. All rights reserved.

Egg traits and physiological neonatal chick parameters from broiler breeder at different ages

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

Humoral immune response of water buffalo monitored with three different antigens of Toxocara vitulorum

Humoral immune response of water buffalo naturally infected with Toxocara vitulorum was monitored using three different antigens of this parasite in serum and colostrum of buffalo cows and calves. Soluble extract (Ex) and excretory/secretory (ES) larval antigens and perienteric fluid antigen (Pe) of adult T vitulorum were used to measure the antibody levels by an indirect ELISA. Serum of 7-12 buffalo cows for the first 365 days and colostrum of the same number of buffalo cows for the first 60 days of parturition, and serum of 8-10 buffalo calves for the first 365 days afterbirth were assayed. The ELISA detected antibodies against all three T vitulorum antigens in the colostrum and serum of 100% of buffalo cows and calves examined. The highest antibody levels against Ex, ES and Pe antigens were detected in the buffalo cow sera during the perinatal period and were maintained at high levels through 300 days after parturition. on the other hand, colostrum antibody concentrations of all three antigens were highest on the first day post-parturition, but decreased sharply during the first 15 days. Concomitantly to the monitoring of immune response, the parasitic status of the calves was also evaluated. In calves, antibodies passively acquired were at the highest concentrations 24 h after birth and remained at high levels until 45 days coincidentally with the peak of T vitulorum infection. The rejection of the worms by the calves occurred simultaneously with the decline of antibody levels, which reached their lowest levels between 76 and 150 days. Thereafter, probably because of the presence of adults/larvae stimulation, the calves acquired active immunity and the antibodies started to increase slightly in the serum and plateaued between the days 211 and 365. All three antigens were detected by the serum antibodies of buffalo calves; however, the concentration of anti-Pe antibody was higher than anti-EX and anti-ES, particularly after 90 days of age. By conclusion, the buffalo cows develop immunity and keep high levels of antibodies against T vitulorum-Ex, ES and Pe antigens and these antibodies are transferred to their calves through the colostrum. This passively acquired immunity does not protect the calves against the acquisition of the infection, but these antibodies, passively or actively acquired, may have an important role during worm rejection by the calves and prevention of intestinal reinfection. (C) 2004 Elsevier B.V. All rights reserved.

Electrical conductivity of the seed soaking solution and soybean seedling emergence

Vigor of soybean [Glycine max (L.) Merrill] seeds can be evaluated by measuring the electrical conductivity (EC) of the seed soaking solution, which has shown a satisfactory relationship with field seedling emergence, but has not had aproper definition of range yet. This work studies the relationship between EC and soybean seedling emergence both in the field and laboratory conditions, using twenty two seed lots. Seed water content, standard germination and vigor (EC, accelerated aging and cold tests) were evaluated under laboratory conditions using -0.03; -0.20; -0.40 and -0.60 MPa matric potentials, and field seedling emergence was also observed. There was direct relationship between EC and field seedling emergence (FE). Under laboratory conditions, a decreasing relationship was found between EC and FE as water content in the substrate decreased, Relationships between these two parameters were also found when -0.03; -0.20 and -0.40 MPa matric potentials were used. EC tests can be used successfully to evaluate soybean seed vigor and identify lots with higher or lower field emergence potential.

Acúmulo e exportação de macronutrientes pelo híbrido de melancia Tide

O objetivo do presente trabalho foi determinar o acúmulo e exportação de macronutrientes pela cultura da melancia, híbrido Tide. O experimento foi conduzido no município de Borborema - SP. As amostragens de plantas foram realizadas aos 15, 30, 45, 60 e 75 dias após transplantio (DAT), para determinação da massa seca e do acúmulo e exportação dos nutrientes (N, P, K, Ca, Mg e S). O acúmulo de massa seca foi lento até os 30 DAT, intensificando-se a partir deste período e atingindo, no final do ciclo, a contribuição média da parte vegetativa de 31% e dos frutos de 69%. Até 30 DAT, o acúmulo de nutrientes também foi pequeno, não ultrapassando 2% do total. Com a frutificação, houve forte incremento na quantidade de nutrientes acumulados. O período de maior demanda para N, Ca e Mg foi de 45 a 60 DAT e para P, K e S de 60 a 75 DAT. do total acumulado, a parte vegetativa foi responsável por 29,6% e os frutos com 70,4%. A ordem decrescente dos nutrientes acumulados pela cultura foi: K>N>Ca>Mg>P>S. Para a produtividade alcançada de 40 t ha-1 observou-se a seguinte exportação de nutrientes pelos frutos: 106,4 kg ha-1 de N, 11,1 kg ha-1 de P, 118,0 kg ha-1 de K, 4,3 kg ha-1 de Ca, 6,8 kg ha-1 de Mg e 6,0 kg ha-1 de S.

Nickel adsorption by soils in relation to pH, organic matter, and iron oxides

There is little information on nickel adsorption by Brazilian soils. The objective of this experiment was to determine the effect of pH, organic matter, and iron oxides on nickel adsorption by three soils: a clayey Anionic Rhodic Acrudox, a sandy clay loam Anionic Xanthic Acrudox, and a clayey Rhodic Hapludalf. Soil samples were collected from the 0-0.2 in layer and treated to eliminate organic matter and iron oxides. The nickel adsorption was evaluated in the original samples and in those treated to remove organic matter and to remove both, organic matter and iron oxides, using 2 g soil + 20 mL of 0.01 mol L-1 CaCl2 solution containing 5 mg L-1 Ni, pH varying from 3.5 to 7.5. The nickel adsorption decreased with the elimination of organic matter. For the samples without organic matter and iron oxides, adsorption decreased only in the Anionic Rhodic Acrudox. The pH was the main factor involved in nickel adsorption variation, and for soil samples without organic matter and iron oxides, the maximum adsorption occurred at higher pH values.

Comparison of selection criteria for pre-weaning growth traits of Nelore cattle

Genetic parameters were estimated for pre-weaning average daily gain (ADG) and number of days to gain 160 kg from birth to weaning (D 160) of Nelore cattle. Ranks of animals were compared for these traits. Heritability estimates were 0.17 and 0.10 for ADG (direct and maternal), and 0.14 and 0.09, for D 160 (direct and maternal). Rank correlations between expected breeding values (EBV) were 0.97 and 0.95, for direct and maternal effects, respectively. Despite similar heritability estimates and high rank correlations, results showed that changes in rank could happen when choosing the best animals according to EBV for D 160 or ADG. There were evidences that sires selected using D 160 would produce progeny that achieve a specified market weight at an earlier age and would be more uniform, since this criterion is calculated as a harmonic mean function. (C) 2003 Elsevier B.V. All rights reserved.

Different criteria of feed formulation for broilers aged 43 to 49 days

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

Modeling energy utilization in broiler breeders, laying hens and broilers

The factorial approach has been used to partition the energy requirements into maintenance, growth, and production. The coefficients determined for these purposes can be used to elaborate energy requirement models. These models consider the body weight, weight gain, egg production, and environmental temperature to determine the energy requirements for poultry. Predicting daily energy requirement models can help to establish better and more profitable feeding programs for poultry. Studies were conducted at UNESP-Jaboticabal to determine metabolizable energy (ME) requirement models for broiler breeders, laying hens, and broilers. These models were evaluated in performance trials and provided good adjustments. Therefore, they could be used to establish nutritional programs. This review aims to outline the results found at UNESP studies and to show the application of models in nutritional programs for broiler breeders, laying hens, and broilers.

Contribuições à análise de robustez de sistemas de controle usando redes neurais

This work develops a robustness analysis with respect to the modeling errors, being applied to the strategies of indirect control using Artificial Neural Networks - ANN s, belong to the multilayer feedforward perceptron class with on-line training based on gradient method (backpropagation). The presented schemes are called Indirect Hybrid Control and Indirect Neural Control. They are presented two Robustness Theorems, being one for each proposed indirect control scheme, which allow the computation of the maximum steady-state control error that will occur due to the modeling error what is caused by the neural identifier, either for the closed loop configuration having a conventional controller - Indirect Hybrid Control, or for the closed loop configuration having a neural controller - Indirect Neural Control. Considering that the robustness analysis is restrict only to the steady-state plant behavior, this work also includes a stability analysis transcription that is suitable for multilayer perceptron class of ANN s trained with backpropagation algorithm, to assure the convergence and stability of the used neural systems. By other side, the boundness of the initial transient behavior is assured by the assumption that the plant is BIBO (Bounded Input, Bounded Output) stable. The Robustness Theorems were tested on the proposed indirect control strategies, while applied to regulation control of simulated examples using nonlinear plants, and its results are presented

Enxertia em plantas de pimentão no controle da murcha de fitóftora em ambiente protegido

Avaliou-se a viabilidade de utilização da enxertia em plantas de pimentão (Capsicum annuum, L.), visando o controle da murcha de fitóftora. A pesquisa foi conduzida de setembro de 2000 a julho de 2001, na UNESP, Botucatu, em ambiente protegido. Adotou-se o delineamento experimental de blocos ao acaso, com 4 repetições e 5 plantas por parcela. Foram utilizados dois porta-enxertos resistentes a Phytophthora capsici, híbridos F1 de Capsicum annuum, e três híbridos comerciais suscetíveis (Elisa, Margarita e Magali-R). A enxertia foi realizada quando porta-enxertos e enxertos apresentavam respectivamente sete e três folhas verdadeiras, pelo método de garfagem fenda simples. Aos 14 dias após o transplante das mudas foi feita a inoculação do fungo, utilizando sementes de trigo infestadas pelo patógeno, depositadas ao redor do colo da planta. Quatro dias após a inoculação, e a partir daí a cada 15 dias, foram feitas avaliações que confirmaram a resistência dos porta-enxertos e a suscetibilidade das plantas não enxertadas. Observou-se bom nível de compatibilidade de enxertia em todas as combinações, precocidade de florescimento das plantas não enxertadas, manutenção de resistência à doença pelas plantas enxertadas durante todo o período e variações na altura das plantas em algumas combinações. Com relação à produção, verificou-se que os frutos mantiveram as características fenotípicas de cada híbrido, revelando que não houve interferência dos porta-enxertos neste aspecto. Concluiu-se haver viabilidade técnica de utilização da enxertia no controle da murcha de fitóftora em ambiente protegido.