906 resultados para Quantities and measurements


Relevância:

80.00% 80.00%

Publicador:

Resumo:

Despite a history of grappling with educational standards, never before has the federal government attempted to establish explicit national standards for what American children should learn in school. Recently, U.S. educators have developed voluntary national content standards, or explicit expectations of what students should know and be able to do. Not surprisingly, this major curriculum reform has provoked considerable debate. Today, teachers face difficult challenges working towards the implementation of standards. The objective of this study was to describe and explain the perceptions of a selected team of fourth-grade teachers regarding the language arts component of their state's Sunshine State Standards (SSS). The exploratory questions that guided this qualitative study were: (a) How are the SSS perceived by these fourth-grade teachers? (b) In what ways do the SSS affect teachers' self-perceptions? and, (c) To what extent and how do the SSS affect the participants' professional classroom behavior? ^ Direct observations, interviews, analysis of relevant documents and the researcher's critical reflective journal served as the methods of inquiry employed in this qualitative study. Bandura's Teacher Self-Efficacy Scale was used as a tool to help categorize the data specifically related to self-perception. ^ Analysis of the data suggests that participants perceived the SSS as a useful guideline as they taught. The SSS were a decisive factor in teachers' planning. They were the actual guide lines used by teachers to plan their lessons. However, participants did not believe the SSS were attainable by all students or were fair to students with special needs. They also believed there was not sufficient time allocated for the effective implementation of the SSS. This lack of time created pressure among some of the participants and others even felt disempowered regarding the curriculum and the instructional focus implemented during the test preparation time. The SSS negatively affected the participants when they felt constraints during this time, which led to their inability to carry out important activities in their classrooms. Thus, the SSS directly affected the participants' behavior in their classrooms. ^

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The taxonomic delimitation at the species level in plants is not an easy task due to the large polymorphism of plants. In this project we aimed to evaluate three morphotypes (forms) of Cryptanthus zonatus (Vis.) Beer ( Bromeliaceae, Bromelioideae ) described in the literature using fl oral biology and phenology, as well as flo ral morphology and leaf anatomy . These studies were conducted in the Parque Estadual das Dunas de Natal, Rio Grande Norte (RN) and Private Reserve of Natural Patrimony Mata Estrela , in the municipality of Ba í a Form osa. The survey of the phenology of the morphotypes involved monthly specimen observation in the field, during one year. In each visit, we observed the status of flowering and fruiting phenophases of the population of the three forms of C. zonatus . For flo ral biology we sought to evaluate data like: observed floral visitors, nectar volume and concentration, time of anthesis and closing of flowers . Flowers of the three fo rms were collected in the field , analyzed by stereomicroscope, and measurements of the f loral pieces were made with the help of a caliper . Transversal and paradermal sections of the leaves of the three forms were stained and then examined under an optical microscope. Observations of the epidermis under scanning electron microscopy were also conducted. The three m orphotypes could not be sepated based on all evidence investigated. Thus, we conclude that there is not evidences to support the recognition of C. zonatus morphotypes as taxonomic entities, and also that the tools of phenology, anatomy, biology and floral morphology were not useful to delimit these three forms . Yet to characterize better the Flora of Bromeli aceae of RN, the leaf anatomy of Orthophytum disjunctum was also studied. Orthophytum is the sister genus to Cryptanthus and only recently documented in the semiarid of RN. The anatomical comparison between Cryptanthus and Orthophytum allowed the separatio n of both genera based on the arrangement of stomata and thickness of aquiferous parênquima . During the fieldwork, it was still possible to document the first occurrence of Aechmea muricata in RN, inside the Mata Estrela preserve, aiding the understanding of the distribution of the taxon that is currently threatened with extinction.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

This study involved the synthesis of photocatalysts based on titanium dioxide (TiO2). The photocatalysts were synthesized by the sol-gel method using three different proportions of acetone (25%, 50% and 75% v/v) in water/acetone mixtures, in order to control the hydrolysis of the precursor of titanium (titanium tetraisopropoxide). Aiming to investigate the structural, morphological and electronic changes provoked by the use of the solvent mixtures, different methodologies were used to characterize the oxides, such as X-ray diffraction (XRD), RAMAN spectroscopy, UV-Vis diffuse reflectance spectroscopy, and measurements of specific surface area (BET). XRD combined to RAMAN analyses revealed that the products are two-phase highly crystalline oxides involving anatase as main phase and brookite. Besides, the refined XRD using the method of Rietveld demonstrated that the presence of acetone during the synthesis influenced in the composition of the crystalline phases, increasing the proportion of the brookite phase between 13 and 22%. The band gap energy of these oxides practically did not suffer changes as function of the synthesis conditions. As shown by the isotherm, these photocatalysts are mesoporous materials with mean diameter of pores of 7 nm and approximately 20% of porosity. The surface area of the oxides prepared by hydrolysis in presence of acetone was 12% higher compared to the bare oxide. After characterized, these oxides had their photocatalytic activities evaluated by photodegradation of the azo dyes Ponceau 4R (P4R), Tartrazine (TTZ) and Reactive Red 120 (RR120), and also by the ability to mediate the photocatalytic production of hydrogen. Using the most efficient photocatalyst, the mineralization achieved for the dyes P4R, RR120 and TTZ was of respectively 83%, 79% and 56% in 120 minutes of reaction, while the discoloration of P4R e RR120 reached 100% and 94% for TTZ. In addition, the same photocatalyst in the presence of 0.5% w/w of Platinum and suspended in a 5:1 v/v water/methanol mixture, produced 56 mmol of gaseous hydrogen in five hours of experiment, corresponding to a specific rate of hydrogen production of 139.5 mmol h-1 g-1.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

We investigate by means of Monte Carlo simulation and finite-size scaling analysis the critical properties of the three dimensional O (5) non-linear σ model and of the antiferromagnetic RP^(2) model, both of them regularized on a lattice. High accuracy estimates are obtained for the critical exponents, universal dimensionless quantities and critical couplings. It is concluded that both models belong to the same universality class, provided that rather non-standard identifications are made for the momentum-space propagator of the RP^(2) model. We have also investigated the phase diagram of the RP^(2) model extended by a second-neighbor interaction. A rich phase diagram is found, where most of the phase transitions are of the first order.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

We investigated gas hydrate in situ inventories as well as the composition and principal transport mechanisms of fluids expelled at the Amsterdam mud volcano (AMV; 2,025 m water depth) in the Eastern Mediterranean Sea. Pressure coring (the only technique preventing hydrates from decomposition during recovery) was used for the quantification of light hydrocarbons in near-surface deposits. The cores (up to 2.5 m in length) were retrieved with an autoclave piston corer, and served for analyses of gas quantities and compositions, and pore-water chemistry. For comparison, gravity cores from sites at the summit and beyond the AMV were analyzed. A prevalence of thermogenic light hydrocarbons was inferred from average C1/C2+ ratios <35 and d13C-CH4 values of -50.6 per mil. Gas venting from the seafloor indicated methane oversaturation, and volumetric gas-sediment ratios of up to 17.0 in pressure cores taken from the center demonstrated hydrate presence at the time of sampling. Relative enrichments in ethane, propane, and iso-butane in gas released from pressure cores, and from an intact hydrate piece compared to venting gas suggest incipient crystallization of hydrate structure II (sII). Nonetheless, the co-existence of sI hydrate can not be excluded from our dataset. Hydrates fill up to 16.7% of pore volume within the sediment interval between the base of the sulfate zone and the maximum sampling depth at the summit. The concave-down shapes of pore-water concentration profiles recorded in the center indicate the influence of upward-directed advection of low-salinity fluids/fluidized mud. Furthermore, the SO42- and Ba2+ pore-water profiles in the central part of the AMV demonstrate that sulfate reduction driven by the anaerobic oxidation of methane is complete at depths between 30 cm and 70 cm below seafloor. Our results indicate that methane oversaturation, high hydrostatic pressure, and elevated pore-water activity caused by low salinity promote fixing of considerable proportions of light hydrocarbons in shallow hydrates even at the summit of the AMV, and possibly also of other MVs in the region. Depending on their crystallographic structure, however, hydrates will already decompose and release hydrocarbon masses if sediment temperatures exceed ca. 19.3°C and 21.0°C, respectively. Based on observations from other mud volcanoes, the common occurrence of such temperatures induced by heat flux from below into the immediate subsurface appears likely for the AMV.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The paper starts from the concern that while there is a large body of literature focusing on the theoretical definitions and measurements of accessibility, the extent to which such measures are used in planning practice is less clear. Previous reviews of accessibility instruments have in fact identified a gap between the clear theoretical assumptions and the infrequent applications of accessibility instruments in spatial and transport planning. In this paper we present the results of a structured-workshop involving private and public stakeholders to test usability of gravity-based accessibility measures (GraBaM) to assess integrated land-use and transport policies. The research is part of the COST Action TU1002 “Accessibility Instruments for Planning Practice” during which different accessibility instruments where tested for different case studies. Here we report on the empirical case study of Rome.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

O presente trabalho, realizado na empresa Amorim & Irmãos, S.A. teve como principal objetivo a avaliação e otimização da lavação de rolhas de cortiça técnicas, designadas por Twin Top®, em termos do perfil de consumo de reagentes químicos e do desenvolvimento da sua brancura. Para tal foi desenvolvida uma metodologia de análise de brancura de rolhas Twin Top® que serviu de base para a determinação de uma gama de brancuras aceitável. Para além disto, efetuou-se a avaliação do processo de lavação atualmente praticado e apartir do qual se realizaram os ensaios de otimização a nível laboratorial e piloto. Foram aplicados diferentes métodos de análise tais como, UV-Vis, FTIR-ATR, RMN e brancura ISO. Tendo como base de análise os espetros de refletância difusa de espetroscopia de UV-Vis foi proposta uma metodologia de determinação da brancura de rolhas Twin Top® a 457nm, adoptando as condições da Norma ISO 3688, aplicada na indústria da pasta e papel. De seguida, aplicando o método anteriormente definido, analisaram-se 1000 rolhas Twin Top® de lavação branca. Sendo que os resultados demonstraram que para rolhas dentro de especificação a brancura ISO deve estar entre os 30 e 35%. Foram ainda analisadas rolhas de diferentes classes visuais e provenientes de várias máquinas de lavação da fábrica para determinar possíveis diferenças. Para proceder à avaliação da lavação existente analisaram-se as colas usadas na produção das rolhas, um grânulo de cortiça e a matéria seca do efluente de lavação por FTIR-ATR e RMN. Desta avaliação resultou a presença de compostos de cortiça e cola degradada no efluente de lavação. Determinou-se a concentração dos reagentes intervenientes no processo que se mostraram de acordo com as especificações indicadas pelos fornecedores. Para a otimização da lavação combinou-se o peróxido de hidrogénio e hidróxido de sódio em diferentes quantidades, concentrações e diferentes tempos de reação o que permitiu identificar a melhor alternativa à lavação convencional. Assim existem duas propostas que devem ser tidas em consideração: uma em que a lavação mantém a mesma sequência da convencional e em que se altera o local de adição dos reagentes, que deve ser o mais próxima e direta possível das rolhas, e a outra em que se reduz o tempo do processo em 29,3 min, que compreende apenas uma oxidação e em que a quantidade de reagentes aplicada corresponde à soma dos volumes de reagentes das três oxidações do processo convencional.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Numerous studies of the dual-mode scramjet isolator, a critical component in preventing inlet unstart and/or vehicle loss by containing a collection of flow disturbances called a shock train, have been performed since the dual-mode propulsion cycle was introduced in the 1960s. Low momentum corner flow and other three-dimensional effects inherent to rectangular isolators have, however, been largely ignored in experimental studies of the boundary layer separation driven isolator shock train dynamics. Furthermore, the use of two dimensional diagnostic techniques in past works, be it single-perspective line-of-sight schlieren/shadowgraphy or single axis wall pressure measurements, have been unable to resolve the three-dimensional flow features inside the rectangular isolator. These flow characteristics need to be thoroughly understood if robust dual-mode scramjet designs are to be fielded. The work presented in this thesis is focused on experimentally analyzing shock train/boundary layer interactions from multiple perspectives in aspect ratio 1.0, 3.0, and 6.0 rectangular isolators with inflow Mach numbers ranging from 2.4 to 2.7. Secondary steady-state Computational Fluid Dynamics studies are performed to compare to the experimental results and to provide additional perspectives of the flow field. Specific issues that remain unresolved after decades of isolator shock train studies that are addressed in this work include the three-dimensional formation of the isolator shock train front, the spatial and temporal low momentum corner flow separation scales, the transient behavior of shock train/boundary layer interaction at specific coordinates along the isolator's lateral axis, and effects of the rectangular geometry on semi-empirical relations for shock train length prediction. A novel multiplane shadowgraph technique is developed to resolve the structure of the shock train along both the minor and major duct axis simultaneously. It is shown that the shock train front is of a hybrid oblique/normal nature. Initial low momentum corner flow separation spawns the formation of oblique shock planes which interact and proceed toward the center flow region, becoming more normal in the process. The hybrid structure becomes more two-dimensional as aspect ratio is increased but corner flow separation precedes center flow separation on the order of 1 duct height for all aspect ratios considered. Additional instantaneous oil flow surface visualization shows the symmetry of the three-dimensional shock train front around the lower wall centerline. Quantitative synthetic schlieren visualization shows the density gradient magnitude approximately double between the corner oblique and center flow normal structures. Fast response pressure measurements acquired near the corner region of the duct show preliminary separation in the outer regions preceding centerline separation on the order of 2 seconds. Non-intrusive Focusing Schlieren Deflectometry Velocimeter measurements reveal that both shock train oscillation frequency and velocity component decrease as measurements are taken away from centerline and towards the side-wall region, along with confirming the more two dimensional shock train front approximation for higher aspect ratios. An updated modification to Waltrup \& Billig's original semi-empirical shock train length relation for circular ducts based on centerline pressure measurements is introduced to account for rectangular isolator aspect ratio, upstream corner separation length scale, and major- and minor-axis boundary layer momentum thickness asymmetry. The latter is derived both experimentally and computationally and it is shown that the major-axis (side-wall) boundary layer has lower momentum thickness compared to the minor-axis (nozzle bounded) boundary layer, making it more separable. Furthermore, it is shown that the updated correlation drastically improves shock train length prediction capabilities in higher aspect ratio isolators. This thesis suggests that performance analysis of rectangular confined supersonic flow fields can no longer be based on observations and measurements obtained along a single axis alone. Knowledge gained by the work performed in this study will allow for the development of more robust shock train leading edge detection techniques and isolator designs which can greatly mitigate the risk of inlet unstart and/or vehicle loss in flight.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The annual report presents information on the following under fisheries section Breaches of Game Laws (Fish Sections) Development and Control of the Lake Victoria Fishing Industry. Collection of Statistics Statistical Tables.- (A) Number of half-yearly licences issued (B) Quantities and value of nets imported (C) Dried fish handled by Railways and Steamers (D) Smoked and salted fish exported to the Belgian Congo Mpondwe Customs Post Lake Bunyonyi Lake Mugisha (or Kaiyumbu) Lake Chahafi Lake Mulehe Lake Mutanda Lake Saka Lake Nabugabo Lake Kachira and Lake Kijanebalola Lake Kyoga Commercial Development:- Lake Edward and associated fisheries Uganda Fisheries Limited Nsonzi Fishery, Kigezi Experimental Nets in Lake Victoria Legislation (B) angling a) Trout (b) Nile pereh or mpufa

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The increasing advancement of agriculture makes providing adequate conditions for the growth and development of plants is the primary purpose of soil management systems. Much of the success of PD is attributed to cultural remains left by cover crops that do not require high nitrogen inputs and can thus be used to reduce nitrogen input in the agro- ecosystem. The nitrogen is one of the elements applied in agriculture, it is absorbed in higher quantities and limiting the yield of grain crops such as corn. Thus, there has been the influence of the no-till and conventional tillage combined with different crops of winter cover and bare soil when in succession to corn, on mineral nitrogen content. The experimental work was made at the experimental station of the Agronomic Institute of Paraná - Iapar. The implemented design was blocks at random split plot with three replications in factorial 6 x 2 x 3 x 5. The main plots were as treatment, beyond the bare soil, 5 winter species (ryegrass, vetch, vetch + oat, oat and radish), while in the subplots were used two tillage systems (No-till and conventional tillage). Three collections made were (before management, the urea before and after the urea), these being held in 5 depths (0-5, 5-10, 10-20, 20-40 and 40-60 cm). So a layer 0-5 cm and a que presents increased amount to NH4 + ion. The use of associated PD system in the presence of winter cover crops decreased as NO3 - losses in soil profile.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

A cutia (Dasyprocta aguti) é um roedor silvestre encontrado amplamente na região Nordeste do Brasil. É uma espécie muito utilizada pela população humana de baixa renda como fonte alternativa de proteína na alimentação. Foram utilizadas 31 cutias, machos, provenientes da Universidade Federal do Piauí (FUFPI), Estado do Piauí e da Escola Superior de Agricultura de Mossoró Estado do Rio Grande do Norte. Os animais foram divididos em grupos etários desde o nascimento até os 14 meses de idade. O diâmetro nuclear médio foi obtido pela medida de 10 núcleos do tipo celular estudado em cada testículo, no estágio 1 do ciclo do epitélio seminífero. Nos animais que não apresentaram o epitélio organizado em estágios bem definidos em virtude da idade, foram feitas medidas em secções transversais escolhidas somente pelo contorno circular. O início da assincronia do processo espermatogênico foi observado a partir dos seis meses de idade. A puberdade, na cutia Dasyprocta aguti, foi definitivamente estabelecida a partir dos nove meses de idade, pois estavam presentes todos os tipos celulares e espermatozóides liberados no lume tubular em grande parte do parênquima testicular.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Tese (doutorado)—Universidade de Brasília, Instituto de Química, Programa de Pós-Graduação em Química, 2015.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

We consider a spectrally-negative Markov additive process as a model of a risk process in a random environment. Following recent interest in alternative ruin concepts, we assume that ruin occurs when an independent Poissonian observer sees the process as negative, where the observation rate may depend on the state of the environment. Using an approximation argument and spectral theory, we establish an explicit formula for the resulting survival probabilities in this general setting. We also discuss an efficient evaluation of the involved quantities and provide a numerical illustration.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

As exigências da sociedade atual obrigam a mudanças tecnológicas cada vez mais rápidas e constantes para satisfazer as necessidades empresariais, especialmente no que concerne à transmissão de informações de forma cada vez mais rápidas, mas sempre mantendo um elevado padrão de qualidade de conteúdos, bem como níveis de segurança elevados para impedir que os mesmos sejam corrompidos. Desde o aparecimento da Internet que a informação circula de forma cada vez mais veloz, em maiores quantidades e alcança cada vez mais pessoas. No entanto, nem todas as pessoas têm acesso a conteúdos de qualidade, sendo nesse ponto que o desenvolvimento do presente trabalho terá importância na respectiva área. O portveb.com é um website que pretende colmatar uma carência de conteúdos de qualidade para especialistas web designers, programadores e optimizadores de motores de busca. A importância do trabalho desenvolvido deve-se à escassez de websites da referida temática, sendo uma oportunidade para explorar a utilização de soluções técnicas como o Bootstrap, HTML, CSS, Javacript, PHP, MYSQL e desenvolver um website cuja funcionalidade não esteja só restrita a computadores pessoais, mas também a plataformas móveis. O desenvolvimento do website portveb.com demonstrou que a utilização das soluções técnicas já referidas foram a melhor opção do que concerne à obtenção de resultados, por assentar em plataformas onde não foi necessário elaborar um design de raíz, sendo que a interacção com bases de dados como PHP e MySQL tornaram o website mais dinâmico. A realização deste trabalho possibilitou ainda a descoberta de potencialidades do website para soluções técnicas futuras que se destinam a aumentar a partilha de conhecimento entre os utilizadores de forma mais prática e eficiente.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2016.