Allelopathic evidence in Brachiaria decumbens and its potential to invade the Brazilian Cerrados

The aim of this study was to look for evidence of allelochemicals in B. decumbens, in parts of the plant from where they could easily be released to the environment. The germination inhibition of Phalaris canariensis, Lactuca sativa (standard species) and Melinis minutiflora, another invasive African grass, was tested using B. decumbens germinating seeds and aqueous leachates of the roots, green and senescent leaves, at 5, 10 and 20% w/v. Both the germinating seeds and the aqueous leachates of B. decumbens reduced the germination of the species tested; the effectiveness of the aqueous leachates increased according to concentration. Apparently, the competitive advantage of B. decumbens in the cerrados could be amplified via allelopathy.

Frugivory and seed dispersal of golden lion tamarin (Leontopithecus rosalia (Linnaeus, 1766)) in a forest fragment in the Atlantic Forest, Brazil

The influence of the golden lion tamarin (Leontopithecus rosalia) as a seed disperser was studied by monitoring two groups of tamarins from December 1998 to December 2000 (871.9 hours of observations) in a forest fragment in south-east Brazil. The tamarins consumed fruits of 57 species from at least 17 families. They ingested the seeds of 39 species, and 23 of these were put to germinate in the laboratory and/or in the field. L. rosalia is a legitimate seed disperser because the seeds of all species tested germinated after ingestion, albeit some in low percentages. These primates do not show a consistent effect in final seed germination, because they benefit some species while damaging others. Feces were examined for seeds that had been preyed upon or digested.

Conteúdos de biologia em vestibulares seriados

A adoção de novos processos seletivos para o acesso de alunos às universidades só foi possível com a promulgação da Lei de Diretrizes e Bases da Educação Nacional n. 9.394/96. O vestibular seriado é uma dessas propostas alternativas, que prevê uma avaliação sistemática dos alunos ao término de cada ano do ensino médio. O propósito deste estudo foi caracterizar o vestibular seriado, hoje presente em 22 instituições públicas, quanto ao seu objetivo, estilos de avaliação e conteúdos da disciplina de Biologia distribuídos nos módulos referentes às três séries do ensino médio. Averiguamos que os diferentes programas analisados não apresentam uniformidade em diversos aspectos, tais como número de vagas, estrutura de avaliação e conteúdo programático. Verificamos, ainda, a ausência de consenso sobre a sequência a ser adotada para o ensino de Biologia e a resultante restrição para que o aluno possa preparar-se para as provas seriadas em mais de uma instituição.

Should reproductively isolated populations of Lutzomyia longipalpis sensu lato receive taxonomically valid names?

A group of 18 research workers involved in different aspects of the biology of Lutzomyia longipalpis discussed whether or not it is important to give taxonomically valid names to populations that have been defined by biological, biochemical and molecular methods to be reproductively isolated. The type material of this medically important species has been lost and because of this it was recommended that a colony should be established from insects captured in the region of the type area and that their description should serve as the basis for future descriptions. It was pointed out that there is a lack of uniformity in the naming of closely related American sand flies and that some of the differences between populations of Lu. longipalpis are greater than those between accepted species. The majority of the participants agreed that the populations that have been defined in the literature as sibling species should be named.

Efeito da fotoperiodicidade na taxa de prenhez em ratos isogênicos (F344)

O uso de animais isogênicos apresenta grandes vantagens experimentais, como uniformidade fenotípica e genotípica (reduzindo o número de animais em experimentos) e histocompatibilidade, permitindo, assim, o acúmulo de informações e a repetibilidade dos experimentos. A linhagem isogênica de Rattus norvegicus Fischer 344 existe há 90 anos, entretanto pouco se sabe sobre as razões de seu baixo índice reprodutivo. O presente estudo demonstrou que ratos Fischer F344 são fotorresponsivos quanto à reprodução, tendo seus índices de prenhezes acrescidos com o aumento do fotoperíodo. Os melhores índices são obtidos quando os machos são submetidos a 14 horas de luz e fêmeas a 16 horas de luz, indicando dimorfismo sexual na fotorresponsividade.

Qualidade de luz na biometria e anatomia foliar de plântulas de Cattleya loddigesii L. (Orchidaceae) micropropagadas

A qualidade de luz pode alterar a morfogênese das plantas por meio de uma série de processos mediados por receptores de luz, principalmente na região do vermelho e azul. O objetivo do presente estudo foi verificar alterações anatômicas foliares e características biométricas de Cattleya loddigesii 'Tipo', cultivadas in vitro, sob diferentes malhas coloridas com nível de radiação de 50% de sombreamento. Plântulas oriundas de autopolinização e sementes germinadas in vitro, com aproximadamente 1,0cm de comprimento e com raízes, foram inoculadas em meio WPM e submetidas a diferentes condições de incubação. Testou-se o efeito de sombrites coloridos (vermelho e azul) sobre os frascos cultivados em casa de vegetação (CV) e sala de crescimento (SC), além dos tratamentos, nos dois ambientes, sem utilização das telas coloridas. A avaliação foi efetuada 180 dias após inoculação. Com os resultados obtidos, observou-se que o ambiente de cultivo promove alterações anatômicas e biométricas em plântulas de Cattleya loddigesii 'Tipo' micropropagadas. As alterações promovidas pelo cultivo em luz natural evidenciam maior capacidade fotossintética, por meio de maior diferenciação dos tecidos clorofilianos, promovendo uma superfície foliar anatomicamente adaptada à fase de aclimatização.

Template-based fluoroethylenepropylene piezoelectrets with tubular channels for transducer applications

We describe the concept, the fabrication, and the most relevant properties of a piezoelectric-polymer system: Two fluoroethylenepropylene (FEP) films with good electret properties are laminated around a specifically designed and prepared polytetrafluoroethylene (PTFE) template at 300 degrees C. After removing the PTFE template, a two-layer FEP film with open tubular channels is obtained. For electric charging, the two-layer FEP system is subjected to a high electric field. The resulting dielectric barrier discharges inside the tubular channels yield a ferroelectret with high piezoelectricity. d(33) coefficients of up to 160 pC/N have already been achieved on the ferroelectret films. After charging at suitable elevated temperatures, the piezoelectricity is stable at temperatures of at least 130 degrees C. Advantages of the transducer films include ease of fabrication at laboratory or industrial scales, a wide range of possible geometrical and processing parameters, straightforward control of the uniformity of the polymer system, flexibility, and versatility of the soft ferroelectrets, and a large potential for device applications e.g., in the areas of biomedicine, communications, production engineering, sensor systems, environmental monitoring, etc.

Análise faunística de himenópteros visitantes florais em fragmento de cerradão em Itirapina, SP

Bees are considered one of the most efficient pollinators. Therefore, they have Indisputable role in the plants reproduction, since they increase the quality and quantity of fruit and seeds, and thus they help the ecosystems maintenance. Cerrado is one of the most affected ecosystems due to the growth of human activities, drastically reducing its biodiversity. The faunistic analysis identifies the species and the size of the populations, and can also indicate the degree of environmental Impact on a particular area. Surveys on flower-visiting hymenoptera in a cerradao area, with 40ha, in the Experimental Station of Itiparina (SP), were conducted every fifteen days from March 2003 to February 2004. From 181 insects collected, the Apidae family was represented by the largest number of species and individuals. The species Apis mellifera (55.8%), Trigona spinipes (14.4%) and Exomalopsis (Exomalopsis) sp. (8.3%) were the most prevalent fit the area. Among the bees species collected, 30.8% were classified as sociable and 69.2% as solitary. Considering all hymenoptera collected, 59.7% preferred the morning period and 40.3% the afternoon period for foraging and/or visiting. The Diversity index (Shannon-Wiener) H was 1.6933, V(H) = 0.0123 and Uniformity index E = 0.5652, following pattern found in other areas of cerrado.

Nutritive value and physical characteristics of Xaraes palisadegrass as affected by grazing strategy

The aim of this study was to ascertain whether the defoliation frequency based on a fixed rest period would generate variable sward structural and physiological conditions at each subsequent grazing event. The relative importance of the physiological age was established in comparison with the chronological age in the determination of the forage nutritive value of Xaraes palisadegrass [Brachiaria brizantha (Hochst ex A. RICH.) STAPF. cv. Xaraes]. Two grazing frequencies were defined by light interception (LI) at initiation of grazing (95% LI - ""target grazing"" [TG] or 100% LI - ""delayed grazing"" [DG]) and one based on chronological time, grazing every 28 days (28-d). Forage produced under the TG schedule was mostly leaves (93%) with a higher concentration of crude protein (CP; 138 g/kg in the whole forage), a lower concentrations of neutral detergent fibre (NDF) in the stems (740 g/kg), and higher in vitro dry matter digestibility (IVDMD) of the leaves (690 g/kg), compared to the other treatments. Lower grazing frequency strategies (DG and 28-d) resulted in forage with higher proportions of stems (10 and 9%, respectively). Strategies based on light interception did not produce pre-graze forage with a uniform nutritive value, as the indicators varied across grazing cycles. The treatment based on fixed days of rest did not result in uniformity.

The Genomic Ancestry of Individuals from Different Geographical Regions of Brazil Is More Uniform Than Expected

Based on pre-DNA racial/color methodology, clinical and pharmacological trials have traditionally considered the different geographical regions of Brazil as being very heterogeneous. We wished to ascertain how such diversity of regional color categories correlated with ancestry. Using a panel of 40 validated ancestry-informative insertion-deletion DNA polymorphisms we estimated individually the European, African and Amerindian ancestry components of 934 self-categorized White, Brown or Black Brazilians from the four most populous regions of the Country. We unraveled great ancestral diversity between and within the different regions. Especially, color categories in the northern part of Brazil diverged significantly in their ancestry proportions from their counterparts in the southern part of the Country, indicating that diverse regional semantics were being used in the self-classification as White, Brown or Black. To circumvent these regional subjective differences in color perception, we estimated the general ancestry proportions of each of the four regions in a form independent of color considerations. For that, we multiplied the proportions of a given ancestry in a given color category by the official census information about the proportion of that color category in the specific region, to arrive at a ""total ancestry"" estimate. Once such a calculation was performed, there emerged a much higher level of uniformity than previously expected. In all regions studied, the European ancestry was predominant, with proportions ranging from 60.6% in the Northeast to 77.7% in the South. We propose that the immigration of six million Europeans to Brazil in the 19(th) and 20(th) centuries - a phenomenon described and intended as the ""whitening of Brazil"" -is in large part responsible for dissipating previous ancestry dissimilarities that reflected region-specific population histories. These findings, of both clinical and sociological importance for Brazil, should also be relevant to other countries with ancestrally admixed populations.

A Morphological and Histological Characterization of Bisexual and Male Flower Types in Pomegranate

Pomegranate [Punica granatum (Punicaceae)] is characterized by having two types of flowers on the same tree: hermaphroditic bisexual flowers and functionally male flowers. This condition, defined as functional andromonoecy, can result in decreased yields resulting from the inability of male flowers to set fruit. Morphological and histological analyses of bisexual and male flowers were conducted using light and scanning electron microscopy (SEM) to characterize the different flower types observed in pomegranate plants and to better understand their developmental differences. Bisexual flowers had a discoid stigma covered with copious exudate, elongated stigmatic papillae, a single elongate style, and numerous stamens inserted on the inner wall of the calyx tube. Using fluorescence staining, high numbers of pollen tubes were observed growing through a central stylar canal. Ovules were numerous, elliptical, and anatropous. In contrast, male flowers had reduced female parts and exhibited shortened pistils of variable heights. Stigmatic papillae of male flowers had little exudate yet supported pollen germination. However, pollen tubes were rarely observed in styles. Ovules in male flowers were rudimentary and exhibited various stages of degeneration. Pollen from both types of flowers was of similar size, approximate to 20 mu m, and exhibited similar percent germination using in vitro germination assays. Pollen germination was strongly influenced by temperature. Maximal germination (greater than 74%) was obtained at 25 and 35 degrees C; pollen germination was significantly lower at 15 degrees C (58%) and 5 degrees C (10%).

Adjustment of Mineral Elements in the Culture Medium for the Micropropagation of Three Vriesea Bromeliads from the Brazilian Atlantic Forest: The Importance of Calcium

Many different species of Bromeliaceae are endangered and their conservation requires specific knowledge of their growth habits and propagation. In vitro culture of bromeliads is an important method for efficient clonal propagation and ill vitro seed g,germination can be used to maintain genetic variability. The present work aims to evaluate the in vitro growth and nutrient concentration in leaves of the epiphyte bromeliads Vriesea friburguensis Mez, Vriesea hieroglyphica (Carriere) E. Morren, and Vriesea unilateralis Mez, which exhibit slow rates of growth in vivo and in vitro. Initially, we compared the endogenous mineral composition of bromeliad plantlets grown in half-strength Murashige and Skoog (MS) medium and the mineral composition considered adequate in the literature. This approach suggested that calcium (Ca) is a critical nutrient and this was considered for new media formulation. Three new culture media were defined in which the main changes to half-strength MS medium were an increase in Ca, magnesium, sulfur, copper, and chloride and a decrease in iron, maintaining the nitrate: ammonium rate at approximate to 2:1. The main difference among the three new media formulated was Ca concentration, which varied from 1.5 mm in half-strength MS to 3.0, 6.0, and 12 mm in M2, M3, and M4 media, respectively. Consistently, all three species exhibited significantly higher fresh and dry weight on M4, the newly defined medium with the highest level of Ca (12 mm). Leaf nitrogen, potassium, zinc, magnesium and boron concentrations increased as Ca concentration in the medium increased from 1.5 to 12 mm.

Optimization of the flow in the catalytic converter of internal combustion engines by means of screens

The flow in the automotive catalytic converter is, in general, not uniform. This significantly affects cost, service life, and performance, in particular, during cold startup. The current paper reports on a device that provided a large improvement in flow uniformity. The device is to be placed in the converter inlet diffuser and is constructed out of ordinary screens. It is cheap and easy to install. Moreover, the device does not present most of the undesired effects, such as increase in pressure drop and time to light off, often observed in other devices developed for the same purpose.

Evaluation of therapeutic ultrasound equipments performance

The therapeutic ultrasound (US) is one of the resources mostly used by physiotherapists; however the use of uncalibrated equipments results in inefficient or even harmful therapies to the patient. In this direction, the objective of this study was to evaluate the performance and the procedures of utilization and maintenance of US in use in clinics and Physical-therapy offices. A questionnaire with questions related to the procedures applied in service during the use of therapeutic ultrasound was applied to physiotherapists. The performance of 31 equipments of 6 different brands and 13 different models was evaluated according to the IEC 61689 norm. The parameters measured were: acoustic power; effective radiating area (AER); non-uniformity ratio of the beam (RBN); maximum effective intensity; acoustic frequency of operation, modulation factor and wave form on pulsate mode. As for the questionnaires, it was evident that the professionals are not concerned about the calibration of the equipment. The results demonstrated that only 32.3% of the equipments were in accordance with the norms for the variables power and effective radiation area. The frequency analysis indicated that 20% of the 3 MHz transducers and 12.5% of the 1 MHz contemplated the norms. In the pulsate mode, 12.7% presented relation rest/duration inside allowed limits. A great variation of the ultrasonic field was observed on the obtained images, which presented beams not centered, sometimes with bifurcation of its apex. The results allow concluding that, although used in therapeutic sessions with the population, none of the equipments presents all the analyzed variables inside technical norms. (C) 2010 Elsevier B. V. All rights reserved.

DEVELOPMENT OF A MICRO-HEAT EXCHANGER WITH STACKED PLATES USING LTCC TECHNOLOGY

A green ceramic tape micro-heat exchanger was developed using Low Temperature Co-fired Ceramics technology (LTCC). The device was designed by using Computational Aided Design software and simulations were made using a Computational Fluid Dynamics package (COMSOL Multiphysics) to evaluate the homogeneity of fluid distribution in the microchannels. Four geometries were proposed and simulated in two and three dimensions to show that geometric details directly affect the distribution of velocity in the micro-heat exchanger channels. The simulation results were quite useful for the design of the microfluidic device. The micro-heat exchanger was then constructed using the LTCC technology and is composed of five thermal exchange plates in cross-flow arrangement and two connecting plates, with all plates stacked to form a device with external dimensions of 26 x 26 x 6 mm(3).