30 resultados para Teaching and learning of Natural Sciences in the early years
em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo (BDPI/USP)
Resumo:
Context. Analysis of ages and metallicities of star clusters in the Magellanic Clouds provide information for studies on the chemical evolution of the Clouds and other dwarf irregular galaxies. Aims. The aim is to derive ages and metallicities from integrated spectra of 14 star clusters in the Small Magellanic Cloud, including a few intermediate/old age star clusters. Methods. Making use of a full-spectrum fitting technique, we compared the integrated spectra of the sample clusters to three different sets of single stellar population models, using two fitting codes available in the literature. Results. We derive the ages and metallicities of 9 intermediate/old age clusters, some of them previously unstudied, and 5 young clusters. Conclusions. We point out the interest of the newly identified as intermediate/old age clusters HW1, NGC 152, Lindsay 3, Lindsay 11, and Lindsay 113. We also confirm the old ages of NGC 361, NGC 419, Kron 3, and of the very well-known oldest SMC cluster, NGC 121.
Resumo:
Dados secundários de uma amostra aleatória de pré-escolares brasileiros foram analisados com o objetivo de avaliar a prevalência de desvios oclusais na dentição decídua, que podem adversamente afetar a dentição permanente, com base em critérios revisados. Overjet e overbite apresentaram pontos de corte descritos na literatura para a remoção dos casos de má oclusão leve. Overjet > 3mm e overbite > 3mm afetaram 16% e 7% das crianças, respectivamente. No plano sagital foram consideradas apenas as taxas de desvios bilaterais: relação molar em degrau distal (9,7%) e mesial (6,0%); relação dos caninos Classe 2 (11,0%) e Classe 3 (2,9%). Para os demais desvios não foram relatados na literatura critérios de severidade. Valores brutos de mordida aberta anterior (27,9%); mordida cruzada posterior (11,3%); apinhamento dentário maxilar (7,0%) e mandibular (11,3%) foram registrados. A avaliação da má oclusão na dentição decídua deve considerar a severidade dos desvios para a identificação de casos e não-casos de relevância em saúde pública. Enfatiza-se a necessidade de maior consenso e melhora na interpretação de dados epidemiológicos sobre a má oclusão nesse estágio de desenvolvimento
Resumo:
Introduction: The ingestion of food products originating from poultry infected with Salmonella spp. is one of the major causes of food poisoning in humans. The control of poultry salmonellosis is particularly difficult since birds are asymptomatic and numerous factors may expedite the maintenance of bacteria in poultry production facilities. Objective: The aim of the study was to determine the vectorial capacity of adults and larvae of Alphitobius diaperinus (Coleoptera: Tenebrionidae) in the experimental transmission of Salmonella Enteritidis phage type 4 to 1-day-old specific pathogen-free White Leghorn chicks. Methods: Adult insects and larvae were starved for 1 day, fed for 24 h or 7 days on sterile ration that had been treated with Salmonella Enteritidis phage type 4, and the levels of bacterial infection were determined. Infected adult insects and larvae were fed to groups of day-old chicks, after which bacteria were recovered from cecum, liver, and spleen samples over a 7-day period. Results: Infected larvae were more efficient than adult insects in transmitting Salmonella Enteritidis to chicks. Higher concentrations of bacteria could be reisolated from the cecum, liver, and spleen of chicks that had ingested infected larvae compared with those that had ingested infected adults. Conclusions: The control of A. diaperinus, and particularly of the larvae, represents a critical factor in the reduction of Salmonella spp. in poultry farms.
Resumo:
We study the evolution of dense clumps and provide an argument that the existence of the clumps is not limited by their crossing times. We claim that the lifetimes of the clumps are determined by turbulent motions on a larger scale, and we predict the correlation of clump lifetime with column density. We use numerical simulations to successfully test this relation. In addition, we study the morphological asymmetry and the magnetization of the clumps as functions of their masses.
Resumo:
Phosphinic-derivative poly(styrene-co-divinylbenzene)-based on PS-DVB copolymers with different porosity degrees have been prepared by aromatic electrophilic substitution reaction using PCl(3)/AlCl(3) followed by base-promoted hydrolysis. The phosphorylation reaction was analyzed by infra-red spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetry (TG/DTG). In addition, the phosphorous content of the phosphorylated copolymers was determined by spectrophotometry using the method based on sodium molybdate reactant so that the extension of that modification could be assessed. The performance of the phosphorylated resins in the extraction of Pb(2+) from aqueous solutions in a batch system was also evaluated. The Pb(2+) content was determined by atomic absorption spectrometry (AAS). These materials presented excellent extraction capacity under the contact time of 30 min and pH 6.
Resumo:
Penicillium chrysogenum is widely used as an industrial antibiotic producer, in particular in the synthesis of g-lactam antibiotics such as penicillins and cephalosporins. In industrial processes, oxalic acid formation leads to reduced product yields. Moreover, precipitation of calcium oxalate complicates product recovery. We observed oxalate production in glucose-limited chemostat cultures of P. chrysogenum grown with or without addition of adipic acid, side-chain of the cephalosporin precursor adipoyl-6-aminopenicillinic acid (ad-6-APA). Oxalate accounted for up to 5% of the consumed carbon source. In filamentous fungi, oxaloacetate hydrolase (OAH; EC3.7.1.1) is generally responsible for oxalate production. The P. chrysogenum genome harbours four orthologs of the A. niger oahA gene. Chemostat-based transcriptome analyses revealed a significant correlation between extracellular oxalate titers and expression level of the genes Pc18g05100 and Pc22g24830. To assess their possible involvement in oxalate production, both genes were cloned in Saccharomyces cerevisiae, yeast that does not produce oxalate. Only the expression of Pc22g24830 led to production of oxalic acid in S. cerevisiae. Subsequent deletion of Pc22g28430 in P. chrysogenum led to complete elimination of oxalate production, whilst improving yields of the cephalosporin precursor ad-6-APA. (C) 2011 Elsevier Inc. All rights reserved.
Resumo:
Marsh deer (Blastocerus dichotomus) is one of the most exposed large mammals in South America. To aid in the conservation management of the species, nine polymorphic microsatellite loci were isolated and tested on up to 50 animals, showing 3-12 alleles and expected heterozygosity values varying from 0.69 to 0.89. These markers should be of considerable utility in future population and ecological genetics studies of this species. The marsh deer (Blastocerus dichotomus) is the biggest South American species of deer. Originally distributed across a large part of South America, stretching from the south bank of the Amazon river to northern Argentina, significant wild populations are now restricted to the Pantanal, swamplands that cover about 40% of southwest Brazil. The marsh deer is listed as Vulnerable on the Red List of the IUCN. Three populations of the species from three areas in the Parana River basin (between the states of Sao Paulo and Mato Grosso do Sul) were recently studied by observing protein polymorphism at 17 loci (Oliveira et al. 2005). Now we are presenting data about isolation of microsatellite markers to improve the results regarding population structure.
Resumo:
Introduction: This cross-sectional retrospective epidemiologic study assessed the relationship between exclusive breastfeeding duration and the prevalence of posterior crossbite in the deciduous dentition. Methods: Clinical examinations were performed in 1377 Brazilian children (690 boys, 687 girls), 3 to 6 years old, from 11 public schools in Sao Paulo, Brazil. Based on questionnaires answered by the parents, the children were classified into 4 groups according to the duration of exclusive breastfeeding: G1, never (119 subjects); G2, less than 6 months (720 subjects); G3, 6 to 12 months (312 subjects); and G4, more than 12 months (226 subjects). The statistical analyses included the chi-square test (P < 0.05) and the odds ratio. Results: The posterior crossbite was observed in 31.1%, 22.4%, 8.3%, and 2.2% of the children, in groups G1, G2, G3, and G4, respectively. The results showed a statistically significant relationship between exclusive breastfeeding duration and the prevalence of posterior crossbite. Conclusions: Children who were breastfed for more than 12 months had a 20-fold lower risk for the development of posterior crossbite compared with children who were never breastfed and a 5-fold lower risk compared with those breastfed between 6 and 12 months. (Am J Orthod Dentofacial Orthop 2010; 137:54-8)
Resumo:
Epidendrum fulgens has a patchy distribution along the Atlantic Rainforest in the Brazilian coast, due to the destruction of its native habitat. Here, we report on both the development of nine new microsatellite markers isolated from this species and the characterization of their allele variability in two distant and unrelated populations. The number of alleles observed for each locus ranged from 2 to 17 with an average of 6.4 alleles per locus. These microsatellites should be valuable tools for studying the effect of habitat fragmentation on the genetic structure of E. fulgens populations.
Resumo:
Objective: To evaluate the transepithelial transport of sodium, glucose, potassium, and water and the mRNA level of the sodium-glucose cotransporter (SGLT1) and the facilitated sugar transporter (GLUT2) in the small intestine of iron-deficient rats. Methods: After 6 wk of receiving diets with low or normal iron content, rats (Wistar-EPM) were subjected to two experiments: 1) evaluation of the transepithelial transport of sodium, glucose, potassium, and water by an ""in vivo"" experimental model of intestinal perfusion and 2) determination of relative SGLT1 and GLUT2 mRNA levels in the proximal, intermediate, and distal portions of the small intestine by the northern blotting technique. Results: Hemoglobin and hepatic iron levels were statistically lower in the anemic rats. The mean transepithelial transports of sodium (-33.0 mu Eq . min(-1) . cm(-1)), glucose (426.0 mu M . min(-1) . cm(-1)), and water (0.4 mu L . min(-1) . cm(-1)) in the small intestine of the anemic rats were significantly lower than in the control group (349.1 mu Eq . min(-1) cm(-1), 842.6 mu M . min(-1) . cm(-1), and 4.3 mu l . min(-1) cm(-1), respectively, P < 0.05). The transepithelial transport of potassium was similar for both groups. The relative SGLT1 mRNA levels of the anemic rats in the intermediate (1.796 +/- 0.659 AU) and distal (1.901 +/- 0.766 AU) segments were significantly higher than the values for the control rats (intermediate 1.262 +/- 0.450 AU, distal 1.244 +/- 0.407 AU). No significant difference was observed for the relative SLGT1 mRNA levels in the proximal segment or for the GLUT2 mRNA levels in all segments. Conclusion: Iron deficiency decreases the absorption of glucose, sodium, and water and increases SGLT1 mRNA in the intermediate and distal segments of the small intestine of rats. (C) 2011 Elsevier Inc. All rights reserved.
Resumo:
We used the fabrics of two granite plutons and U/Pb (SHRIMP) zircon ages to constrain the tectonic evolution of the E-trending Patos shear zone (Borborema Province, NE Brazil). The pre-tectonic Teixeira batholith consists of an amphibole leucogranite locally with aegirine-augite. Zircons from a syenogranite yielded crystallization ages of 591 +/- 5 Ma. The batholith fabrics were determined by anisotropy of magnetic susceptibility (AMS) and mineral shape preferred orientation. The fabrics support pre-transcurrent batholith emplacement, as evidenced by: (i) magmatic/magnetic fabrics in low susceptibility (<0.35 mSI) leucogranites highly discordant to the regional host rock structure, and (ii) concordant magnetic fabrics restricted to high susceptibility (>1 mSI) corridors connected to shear zones branching off from Patos. One of these satellite shear zones controlled the syntectonic emplacement of the Serra Redonda pluton, which yields a crystallization age of 576 +/- 3 Ma. This late shearing event marks the peak regional deformation that, south of Patos, was coupled to crustal shortening nearly perpendicular to the shear belt. The chronology of the deformational events indicates that the major shear zones of the eastern Borborema are late structures active after the crustal blocks amalgamated. (C) 2007 Elsevier Ltd. All rights reserved.
Resumo:
The amygdala, the dorsal periaqueductal gray (dPAG), and the media] hypothalamus have long been recognized to be a neural system responsible for the generation and elaboration of unconditioned fear in the brain. It is also well known that this neural substrate is under a tonic inhibitory control exerted by GABA mechanisms. However, whereas there is a growing body of evidence to suggest that the amygdala and dPAG are also able to integrate conditioned fear, it is still unclear, however, how the distinct hypothalamic nuclei participate in fear conditioning. In this work we aimed to examine the extent to which the gabaergic mechanisms of this brain region are involved in conditioned fear using the fear-potentiated startle (FPS). Muscimol, a GABA-A receptor agonist, and semicarbazide, an inhibitor of the GABA synthesizing enzyme glutamic acid decarboxylase (GAD), were used as an enhancer and inhibitor of the GABA mechanisms, respectively. Muscimol and semicarbazide were injected into the anterior hypothalamus (AHN). the dorsomedial part of the ventromedial nucleus (VMHDM), the dorsomedial (DMH) or the dorsal premammillary (PMD) nuclei of male Wistar rats before test sessions of the fear conditioning paradigm. The injections into the DMH and PMD did not produce any significant effects on FPS. On the other hand, muscimol injections into the AHN and VMHDM caused significant reduction in FPS. These results indicate that injections of muscimol and semicarbazide into the DMH and PMD fail to change the FPS, whereas the enhancement of the GABA transmission in the AHN and VMHDM produces a reduction of the conditioned fear responses. On the other hand, the inhibition of this transmission led to an increase of this conditioned response in the AHN. Thus, whereas DMH and PMD are known to be part of the caudal-most region of the medial hypothalamic defensive system, which integrates unconditioned fear, systems mediating conditioned fear select the AHN and VMHDM nuclei that belong to the rostral-most portion of the hypothalamic defense area. Thus, distinct subsets of neurons in the hypothalamus could mediate different aspects of the defensive responses. (C) 2008 Elsevier Inc. All rights reserved.
Resumo:
Some factors complicate comparisons between linkage maps from different studies. This problem can be resolved if measures of precision, such as confidence intervals and frequency distributions, are associated with markers. We examined the precision of distances and ordering of microsatellite markers in the consensus linkage maps of chromosomes 1, 3 and 4 from two F 2 reciprocal Brazilian chicken populations, using bootstrap sampling. Single and consensus maps were constructed. The consensus map was compared with the International Consensus Linkage Map and with the whole genome sequence. Some loci showed segregation distortion and missing data, but this did not affect the analyses negatively. Several inversions and position shifts were detected, based on 95% confidence intervals and frequency distributions of loci. Some discrepancies in distances between loci and in ordering were due to chance, whereas others could be attributed to other effects, including reciprocal crosses, sampling error of the founder animals from the two populations, F(2) population structure, number of and distance between microsatellite markers, number of informative meioses, loci segregation patterns, and sex. In the Brazilian consensus GGA1, locus LEI1038 was in a position closer to the true genome sequence than in the International Consensus Map, whereas for GGA3 and GGA4, no such differences were found. Extending these analyses to the remaining chromosomes should facilitate comparisons and the integration of several available genetic maps, allowing meta-analyses for map construction and quantitative trait loci (QTL) mapping. The precision of the estimates of QTL positions and their effects would be increased with such information.
Resumo:
This article examines the subject matter of learning within the context of information society, through an inquiry concerning both the reforms in education adopted in Brazil in the last thirty years and their results. It provides a revision on the explanations of school failure based on assumptions of learning problems due to cognitive and linguistic deficits. From the guidelines related with written school forms as well as the constant cultural oppression accomplished inside the school, the article claims the necessity of changing the psychological and pedagogic views that, under the label of democratic practices, determine school institutions and its daily life, by means of instrumental relations with knowledge that disregard the reading practices which are congenial to popular culture.