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Soil density evaluated by spectral reflectance as an evidence of compaction effects

DEMATTE, J. A. M.; NANNI, M. R.; SILVA, A. P. da; MELO FILHO, J. F. de; SANTOS, W. C. Dos; CAMPOS, R. C.
Fonte: TAYLOR & FRANCIS LTD Publicador: TAYLOR & FRANCIS LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.07%
Soil compaction, reflected by high bulk density, is an environmental degradation process and new technologies are being developed for its detection. Despite the proven efficiency of remote sensing, it has not been widely used for soil density. Our objective was to evaluate the density of two soils: a Typic Quartzpisament (TQ) and a Rhodic Paleudalf (RP), using spectral reflectance obtained by a laboratory spectroradiometer between 450 and 2500 nm. Undisturbed samples were taken at two depths (0-20 and 60-80 cm), and were artificially compacted. Spectral data, obtained before and after compaction, were compared for both wet and dried compacted samples. Results demonstrated that soil density was greater in RP than in TQ at both depths due to its clayey texture. Spectral data detected high density (compacted) from low density (non-compacted) clayey soils under both wet and dry conditions. The detection of density in sandy soils by spectral reflectance was not possible. The intensity of spectral reflectance of high soil bulk density (compacted) samples was higher than for low density (non-compacted) soils due to changes in soil structure and porosity. Dry samples with high bulk density showed differences in the spectral intensity, but not in the absorption features. Wet samples in equal condition had statistically higher reflectance intensity than that of the low soil bulk density (non-compacted)...

The effects of stocking density in physiological parameters and growth of the endangered teleost species piabanha, Brycon insignis (Steindachner, 1877)

TOLUSSI, Carlos Eduardo; HILSDORF, Alexandre Wagner Silva; CANEPPELE, Danilo; MOREIRA, Renata Guimaraes
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.08%
This study investigated the effects of stocking density on the growth and fatty acid (FA) of Brycon insignis metabolism. Fingerlings (360) were distributed into eight ponds at two stocking densities (105 and 210 g/m(3)). The analysis of growth showed that the condition factor (K) and the coefficient of variation (CV) for body mass were not affected by stocking density. However, final body mass and length, specific growth rate (SGR), and weight gain (WG) were higher in the low stocking density group, which also presented a higher feed efficiency (FE) and survival (S). By contrast, muscle protein levels were higher in the high stocking density group. The plasma and muscle lipid content were not affected by stocking density, but fish reared at lower stocking density presented higher lipid concentration in the liver, with no differences in hepatosomatic index values. Even with the differences observed in metabolic and growth parameters, plasma cortisol was not affected by stocking density. The FA profile in the muscle and liver neutral fraction were not affected by stocking density, but the FA in the polar fractions differed between the two stocking densities. In the liver, total polyunsaturated fatty acids (PUFA) and PUFA n - 3 increased in higher stocking density...

Bone mineral density and body composition in girls with idiopathic central precocious puberty before and after treatment with a gonadotropin-releasing hormone agonist

Alessandri, Sandra B.; Pereira, Francisco de A.; Villela, Rosangela A.; Antonini, Sonir Roberto Rauber; Elias, Paula C. L.; Martinelli Jr., Carlos E.; Castro, Margaret de; Moreira, Ayrton Custodio; Paula, Francisco Jose Albuquerque de
Fonte: HOSPITAL CLINICAS, UNIV SAO PAULO; SÃO PAULO Publicador: HOSPITAL CLINICAS, UNIV SAO PAULO; SÃO PAULO
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.03%
OBJECTIVES: Idiopathic central precocious puberty and its postponement with a (gonadotropin-releasing hormone) GnRH agonist are complex conditions, the final effects of which on bone mass are difficult to define. We evaluated bone mass, body composition, and bone remodeling in two groups of girls with idiopathic central precocious puberty, namely one group that was assessed at diagnosis and a second group that was assessed three years after GnRH agonist treatment. METHODS: The precocious puberty diagnosis and precocious puberty treatment groups consisted of 12 girls matched for age and weight to corresponding control groups of 12 (CD) and 14 (CT) girls, respectively. Bone mineral density and body composition were assessed by dual X-ray absorptiometry. Lumbar spine bone mineral density was estimated after correction for bone age and the mathematical calculation of volumetric bone mineral density. CONEP: CAAE-0311.0.004.000-06. RESULTS: Lumbar spine bone mineral density was slightly increased in individuals diagnosed with precocious puberty compared with controls; however, after correction for bone age, this tendency disappeared (CD = -0.74 +/- 0.9 vs. precocious puberty diagnosis = -1.73 +/- 1.2). The bone mineral density values of girls in the precocious puberty treatment group did not differ from those observed in the CT group. CONCLUSION: There is an increase in bone mineral density in girls diagnosed with idiopathic central precocious puberty. Our data indicate that the increase in bone mineral density in girls with idiopathic central precocious puberty is insufficient to compensate for the marked advancement in bone age observed at diagnosis. GnRH agonist treatment seems to have no detrimental effect on bone mineral density.; Fundacao de Apoio a Pesquisa do Estado de Sao Paulo (FAPESP) [61398-8]; Fundacao de Apoio a Pesquisa do Estado de Sao Paulo (FAPESP)

Espaçamentos ultra-adensado, adensado e convencional com densidade populacional variável em algodoeiro.; Ultra-narrow row, narrow row and conventional row with cotton variable density plant population.

Silva, Ariana Vieira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/01/2003 PT
Relevância na Pesquisa
36.03%
No presente estudo foi avaliado a densidade populacional, por espaçamentos ultra-adensado, adensado e convencional entre fileiras e número de plantas por metro linear, através do crescimento, desenvolvimento e produtividade da cultivar de algodão IAC 23. O experimento foi conduzido na área experimental da ESALQ/USP, município de Piracicaba, Estado de São Paulo, no ano agrícola de 2001/02. O delineamento experimental foi o de blocos ao acaso em esquema fatorial, com 4 repetições, sendo três espaçamentos entre linhas (0,38, 0,76 e 0,95 m) e quatro densidades de plantas por metro linear (5, 8, 11 e 14). O controle da altura das plantas foi realizado através de regulador de crescimento. Em cada parcela experimental foram marcadas seis plantas ao acaso e analisados os seguintes parâmetros: estádios fenológicos, altura média das plantas, altura de inserção do 1º ramo frutífero, diâmetro do caule, número de ramos vegetativos e frutíferos, número de internódios e o número de capulhos por planta. Em duas plantas foram avaliados o índice de área foliar e a massa seca da parte aérea. Na área útil de cada parcela foi determinada a produção de algodão em caroço, a precocidade de colheita e em amostras de 20 capulhos por parcela foram realizadas as análises dos caracteres agronômicos de laboratório (massa média de uma capulho...

Densidade mamográfica antes e após o uso de tibolona: auxílio da informática; Mamographic Density Before and After the Use of Tibolone: Computer Help

Carloni, Marcelo Ballaben
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 26/01/2007 PT
Relevância na Pesquisa
36.03%
A terapia hormonal na menopausa tem sido objeto de muita contradição nos últimos anos, pois trabalhos mostram resultados contraditórios quanto a benefícios e riscos para as usuárias. Ficou demonstrada, em alguns trabalhos, a maior incidência de carcinoma de mama em usuárias de terapia hormonal clássica e, portanto, existe uma constante busca no que diz respeito ao refinamento de métodos diagnósticos e avaliação dos efeitos das novas drogas na mama. Dentre as drogas mais modernas, a tibolona vem se destacando por apresentar poucos efeitos colaterais, principalmente relacionados à mama. Esta droga apresenta três metabólitos com ação tecidual específica. Assim, efeitos androgênicos, estrogênicos ou progesterônicos podem ser observados na dependência do órgão alvo estudado. Os objetivos de nosso estudo foram avaliar um método de análise computadorizada da densidade mamográfica e, ao mesmo tempo, avaliar os efeitos da tibolona na densidade dessas mamografias. Em nosso estudo, foram avaliadas 26 pacientes na pós menopausa e que tinham indicação do uso de terapia hormonal oral, de acordo com o protocolo vigente no Setor de Endocrinologia Ginecológica do Centro de Saúde Escola da Faculdade de Medicina de Ribeirão Preto-USP. Essas pacientes receberam tibolona na dose de 2...

Tomografia de impulso para estimativa da densidade da madeira; Impulse tomography for wood density estimate

Rollo, Luciana Cavalcante Pereira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 11/02/2010 PT
Relevância na Pesquisa
36.04%
Há diversas técnicas que utilizam a passagem de ondas através da madeira para obtenção de informações. Dentre elas destaca-se a tomografia de árvores que reconstrói seções transversais de tronco e galhos. A tomografia de impulso, por sua vez, se baseia na cronometragem da viajem de ondas mecânicas sonoras entre sensores anexados em uma seção transversal da árvore, para cálculo da velocidade da onda e construção da imagem tomográfica. Sabe-se que a velocidade de passagem das ondas mecânicas é determinada pelas propriedades físico-mecânicas da madeira. Em especial: o módulo de elasticidade, a densidade e a umidade. Até o momento, há diversos estudos sobre a correlação entre a velocidade de onda (principalmente ultrassom) e o módulo de elasticidade. Os estudos apresentados a seguir se destacam por avaliar a correlação entre a velocidade de onda mecânica, obtida por tomografia de impulso, e a densidade da madeira, com vistas em utilizá-la como ferramenta na estimativa da densidade. Os diversos métodos consagrados para a determinação da densidade se caracterizam por utilizar amostras de madeira, que em muitos casos são de difícil obtenção. Além de serem executados procedimentos laboratoriais que podem levam até semanas. Dessa forma...

Teoria do funcional da densidade para sistemas espacialmente correlacionados; Density functional theory for systems spatially correlated

Lima, Neemias Alves de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 26/04/2002 PT
Relevância na Pesquisa
36.04%
A aproximação da densidade local para a teoria do funcional da densidade tem, no passado, levado a resultados conflitantes para a dimerização de cadeias infinitas do trans-poliacetileno (trans-PA). Estes resultados variaram deste forte dimerização, próximo dos resultados experimentais, até fraca dimerização, ou até mesmo nenhuma dimerização. Desde que a aproximação da densidade local usualmente descreve transições de fase estruturais corretamente, esta situação insatisfatória no caso do trans-PA clama por uma investigação detalhada. Neste trabalho estudamos o problema descrevendo a molécula como um modelo de Hubbard-Peierls unidimensional. Estabelecemos uma teoria do funcional da densidade e construímos uma aproximação da densidade local para este modelo. Em acordo com os cálculos ab initio encontramos que este tipo de aproximação não descreve adequadamente a dimerização. Propomos então um Formalismo alternativo, baseado em funcionais da matriz-densidade. Neste formalismo a energia de troca-correlação é escrita como um funcional da densidade de carga (como no método tradicional) e do parâmetro de ordem para a transição. Desta maneira obtemos um tratamento aperfeiçoado para a fase dimerizada. Nossos resultados sugerem que uma descrição adequada de sistemas espacialmente correlacionados dentro da teoria do funcional da densidade requer uma nova classe de funcionais...

Corn root length density and root diameter as affected by soil compaction and soil water content

Duruoha, Charles; Piffer, Cassio Roberto; Silva, Paulo Arbex
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 14-26
ENG
Relevância na Pesquisa
36.04%
Negative effects of soil compaction have been recognized as one of the problems restricting the root system and consequently impairing yields, especially in the Southern Coastal Plain of the USA. Simulations of the root restricting layers in green house studies are necessary for the development of mechanism which alleviates soil compaction problems in these soils. The selection of three distinct bulk densities based on the standard proctor test is also an important factor to determine which bulk density restricts the root layer. The experiment was conducted to assess the root length density and root diameter of the corn (Zea mays L.) crop as a function of bulk density and water stress, characterized by the soil density (1.2; 1.4, and 1.6 g cm -3), and two levels of the water content, approximately (70 and 90% field capacity). The statistical design adopted was completely randomized design, with four replicates in a factorial pattern of (3 × 2). The PVC tubes were superimposed with an internal diameter of 20 cm with a height of 40 cm (the upper tube 20 cm, compacted and inferior tube 10 cm), the hardpan with different levels of soil compaction were located between 20 and 30 cm of the depth of the pot. Results showed that: the main effects of subsoil mechanical impedance were observed on the top layer indicating that the plants had to penetrate beyond the favorable soil conditions before root growth was affected from 3.16; 2.41 to 1.37 cm cm -3 (P<0.005). There was a significant difference at the hardpan layer for the two levels of water and 90% field capacity reduced the root growth from 0.91 to 0.60 cm cm -3 (P<0.005). The root length density and root diameter were affected by increasing soil bulk density from 1.2 to 1.6 g cm -3 which caused penetration resistance to increase to 1.4 MPa. Soil water content of 70% field capacity furnished better root growth in all the layers studied. The increase in root length density resulted in increased root volume. It can also be concluded that the effect of soil compaction impaired the root diameter mostly at the hardpan layer. Soil temperature had detrimental effect on the root growth mostly with higher bulk densities.

Low bone mineral density in noncholestatic liver cirrhosis: prevalence, severity and prediction

Figueiredo,Fátima Aparecida Ferreira; Brandão,Cynthia; Perez,Renata de Mello; Barbosa,Walnei Fernandes; Kondo,Mario
Fonte: Instituto Brasileiro de Estudos e Pesquisas de Gastroenterologia - IBEPEGE ; Colégio Brasileiro de Cirurgia Digestiva - CBCD ; Sociedade Brasileira de Motilidade Digestiva - SBMD ; Federação Brasileira de Gastroenterologia - FBG; Sociedade Brasileira de Hepatologia - SBH; Sociedade Brasileira de Endoscopia Digestiva - SOBED Publicador: Instituto Brasileiro de Estudos e Pesquisas de Gastroenterologia - IBEPEGE ; Colégio Brasileiro de Cirurgia Digestiva - CBCD ; Sociedade Brasileira de Motilidade Digestiva - SBMD ; Federação Brasileira de Gastroenterologia - FBG; Sociedade Brasileira de Hepatologia - SBH; Sociedade Brasileira de Endoscopia Digestiva - SOBED
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2003 EN
Relevância na Pesquisa
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BACKGROUND: Metabolic bone disease has long been associated with cholestatic disorders. However, data in noncholestatic cirrhosis are relatively scant. AIMS: To determine prevalence and severity of low bone mineral density in noncholestatic cirrhosis and to investigate whether age, gender, etiology, severity of underlying liver disease, and/or laboratory tests are predictive of the diagnosis. PATIENTS/METHODS: Between March and September/1998, 89 patients with noncholestatic cirrhosis and 20 healthy controls were enrolled in a cross-sectional study. All subjects underwent standard laboratory tests and bone densitometry at lumbar spine and femoral neck by dual X-ray absorptiometry. RESULTS: Bone mass was significantly reduced at both sites in patients compared to controls. The prevalence of low bone mineral density in noncholestatic cirrhosis, defined by the World Health Organization criteria, was 78% at lumbar spine and 71% at femoral neck. Bone density significantly decreased with age at both sites, especially in patients older than 50 years. Bone density was significantly lower in post-menopausal women patients compared to pre-menopausal and men at both sites. There was no significant difference in bone mineral density among noncholestatic etiologies. Lumbar spine bone density significantly decreased with the progression of liver dysfunction. No biochemical variable was significantly associated with low bone mineral density. CONCLUSIONS: Low bone mineral density is highly prevalent in patients with noncholestatic cirrhosis. Older patients...

Spectral features of E- and F-region plasma irregularities as observed by rocket-borne electron density probes from Brazil

Muralikrishna,Polinaya; Vieira,Leandro Paulino; Abdu,Mangalathayil Ali
Fonte: Sociedade Brasileira de Geofísica Publicador: Sociedade Brasileira de Geofísica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2007 EN
Relevância na Pesquisa
36.04%
The height variation of the ionospheric electron density was measured with rocket-borne electron density probes from Alcântara (2.31ºS; 35.2ºW) in Brazil. A Black Brant X sounding rocket was launched on 14-th October 1994 at 19h55min (LT) to investigate the phenomenon of high-altitude equatorial spread-F events. Ground equipments were operated during the campaign to ensure that the rocket was launched under conditions favorable for the generation of plasma bubbles in the F-region. The electron density was measured by three different types of probes. A High Frequency Capacitance probe (HFC) gave density data with low height resolution, while a conventional Langmuir Probe (LP) and a Plasma Frequency Probe (PFP) measured the electron density and the spatial fluctuations in it. The k-spectra of the plasma irregularities were obtained by the spectral analysis of the electron density fluctuation data. An important feature observed was the continuous presence of plasma irregularities of a large range of vertical scale sizes in the altitude range of 340 km to 817 km. The electron number density varied considerably in these spatial structures, for example a decrease by a factor of 2.6 in a vertical extension of 1 km near the altitude of 497 km. Near 535 km altitude the electron density increased by a factor of 1.8 within a height range of 2.7 km. Density structures of vertical scale sizes in the range of hundreds of meters also were observed superposed on the large-scale structures. During the rocket upleg two height regions of intense irregularities were observed...

Density-Based Separations in Aqueous Multiphase Systems: Tools for Biological Research and Low-Cost Diagnostics

Kumar, Ashok Ashwin
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
EN_US
Relevância na Pesquisa
36.06%
Cells often exist in heterogeneous mixtures. Density provides a property to separate several types of cells from the mixed sample in which they originate. Density-based separation methods provide a standard method to quickly separate or enrich specific populations of cells, such as lymphocytes from whole blood. This dissertation explores the use of aqueous multiphase systems (AMPS) as self-forming step-gradients in density for the separation of cells. AMPS were first discovered over a hundred years ago as aqueous two-phase systems. Density as a tool to separate cells is at least as old. Despite this long history, the work in this thesis is the first work to use AMPS to perform density-based separations on cells. This combination provides a powerful technique to separate cells and enable new testing at the point-of-care. Chapter 1 provides a short overview of aqueous multiphase systems and density-based separations of cells. Chapter 2 describes the process of taking technology, including AMPS, from a demonstration in a laboratory to a large scale evaluation in a field setting. In Chapter 3 and Appendix I, AMPS provide a means to enrich reticulocytes from whole blood as a means to grow malaria parasites. Chapter 4 and Appendix II describe the development and proof-of-prinicple of a density-based diagnostic test for sickle cell disease (SCD) using AMPS. Chapter 5 and Appendix III detail the results of a large scale field evaluation of a rapid test for SCD using AMPS in Zambia. Demonstrations of AMPS for density- and size-based separations are provided in Appendices IV and V. Appendix VI demonstrates the general usefulness of density to separate crystal polymorphs with another density-based separation method: magnetic levitation in a paramagnetic fluid. Beyond density...

The effect of density on the near field of a naturally occurring oscillating jet.

England, Grant
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2009
Relevância na Pesquisa
36.08%
A major component of the world’s ever increasing energy demand is supplied by combustion. Despite concerns of the enhanced greenhouse effect, primarily due to the emission of CO₂, fossil fuels will remain a major energy source for the foreseeable future. One approach to help to combat the enhanced greenhouse effects of combustion is to design highly efficient burners that achieve low levels of pollution. The fluidic precessing jet (FPJ) and the related triangular oscillating jet (TOJ) burners have shown such benefits when used in the cement and lime industry. As a result, they have been studied at the University of Adelaide for many years. Despite these investigations there are still significant gaps in the understanding of how they work. Addressing these gaps will allow their design to be improved. This work focuses on improving the understanding of the TOJ, and also provides insight into the understanding of the FPJ. The benefits that can be provided by the FPJ and TOJ nozzles include fuel savings of up to 10% and NOₓ reduction between 40-70%. This is due to the flows they produce. These flows are unsteady, creating large scale unique eddies that alter the mixing of the fuel and air, and hence the combustion. Many nozzle parameters...

Colloidal Hard Sphere Crystals and their Interfaces in Density Functional Theory; Kolloidale harte Kugeln und ihre Grenzflächen in Dichtefunktionaltheorie

Yamani, Mohammad Hossein
Fonte: Universität Tübingen Publicador: Universität Tübingen
Tipo: Dissertação
EN
Relevância na Pesquisa
36.07%
The research reported in this thesis addresses necessary equilibrium information for understanding of homogeneous and heterogeneous nucleation in the hard sphere system. Colloidal hard spheres are an intensely studied model system for addressing the nucleation problem. Understanding nucleation requires a precise knowledge about equilibrium crystal structures and free energies. We use classical density functional theory (DFT) of fundamental measure type (FMT) to evaluate the fully minimized crystal density profiles and their interfaces. Results are compared with simulation data and complemented by a cluster expansion approach due to Stillinger which is based on expanding the crystal partition function in terms of the number n of free particles while the remaining particles are pinned at their ideal lattice positions. Finally, dynamical density functional theory (DDFT) as a time dependent extension of static DFT is implemented. Face-centered cubic (fcc), hexagonally close-packed (hcp) and body-centered cubic (bcc) crystals are investigated using fundamental measure theory and results are complemented by results from Stillinger’s approach. Two branches of solutions have been observed for bcc structure corresponding to different width parameters of the density distribution around lattice sites. The free energy of one branch of bcc agrees well with FMT and Stillinger’s approximation truncated at n = 2. A second branch of the bcc solution features rather spread-out density distributions around lattice sites and a large equilibrium vacancy concentration and it is presumably linked to the shear instability of the bcc phase. Within fundamental measure theory and Stillinger approach (n = 2)...

Absolute instability in the near field of low-density jets

Coenen, Wilfried
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: info:eu-repo/semantics/doctoralThesis; info:eu-repo/semantics/doctoralThesis Formato: application/octet-stream; application/octet-stream; application/pdf
ENG
Relevância na Pesquisa
36.04%
Variable density jets are known to support self-sustained oscillations when the jet-to-ambient density ratio is sufficiently small. This change in dynamical response to small perturbations is associated with a transition from convective to absolute instability of the underlying unperturbed base flow. The focus of this dissertation lies in the use of linear stability theory to describe the convective to absolute instability transition of buoyancy-free low-density jets emerging from a circular injector tube at moderately high Reynolds numbers and low Mach numbers. Particular interest is given to the in- fluence of the length of the injector tube on the stability characteristics of the resulting jet flow, whose base velocity profile at the jet exit is computed in terms of the nondimen- sional tube length L$_{t}$ by integrating the boundary layer equations along the injector. We begin with the investigation of inviscid axisymmetric and helical modes of in- stability in a heated jet for different values of the jet-to-ambient density ratio. For short tubes L$_{t}$ $ll$ 1 the base velocity profile at the tube exit is uniform except in a thin sur- rounding boundary layer. Correspondingly, the stability analysis reproduces previous results of uniform velocity jets...

Sustainable density: form, built environment, energy; Densità sostenibile: forma, ambiente costruito, energia

MORGANTI, MICHELE
Fonte: La Sapienza Universidade de Roma Publicador: La Sapienza Universidade de Roma
Tipo: Tese de Doutorado
IT
Relevância na Pesquisa
36.07%
This research aims at exploring meaning, quality and analytical capacity of density concept and its potential interpretations in architecture and sustainability fields. Its goal is to determine the relationships among built environment, energy and form of urban textures in Mediterranean compact city, taken density as useful parameter to illustrate their features. Despite the growing unsustainability of today’s city facing an effective energy and environmental crisis, recent statistics have confirmed the increasing attractive power of metropolitan areas. Within the context of European compact city, new building models, based on energy conservation, account for an insignificant percentage compared to existing city whose functioning remarkably affects the efficiency of the whole metropolitan system. Therefore, an approach determining instruments and design methods at both urban and architectural scale, should be found in order to set out conditions more appropriate to the compact city. In respect of this kind of scale, the relationship between energy and form takes a central role in the variation of energy performances; at the same time the concept of density has showed itself as an efficient instrument of analysis of the morphological performances of the built form. This research is composed by five interconnected parts. The first one examines urban and energy dynamics’ current conditions to comprehend the role and contribution of the building industry considering the scientific progress and the implementation of present operational instruments. The second one investigates role and evolution of the density concept as parameter...

Strength of evidence for density dependence in abundance time series of 1198 species

Brook, B.; Bradshaw, C.
Fonte: Ecological Soc Amer Publicador: Ecological Soc Amer
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
Relevância na Pesquisa
36.04%
Population limitation is a fundamental tenet of ecology, but the relative roles of exogenous and endogenous mechanisms remain unquantified for most species. Here we used multi-model inference (MMI), a form of model averaging, based on information theory (Akaike's Information Criterion) to evaluate the relative strength of evidence for density-dependent and density-independent population dynamical models in long-term abundance time series of 1198 species. We also compared the MMI results to more classic methods for detecting density dependence: Neyman-Pearson hypothesis-testing and best-model selection using the Bayesian Information Criterion or cross-validation. Using MMI on our large database, we show that density dependence is a pervasive feature of population dynamics (median MMI support for density dependence = 74.7-92.2%), and that this holds across widely different taxa. The weight of evidence for density dependence varied among species but increased consistently with the number of generations monitored. Best-model selection methods yielded similar results to MMI (a density-dependent model was favored in 66.2-93.9% of species time series), while the hypothesis-testing methods detected density dependence less frequently (32.6-49.8%). There were no obvious differences in the prevalence of density dependence across major taxonomic groups under any of the statistical methods used. These results underscore the value of using multiple modes of analysis to quantify the relative empirical support for a set of working hypotheses that encompass a range of realistic population dynamical behaviors.; Barry W. Brook and Corey J.A. Bradshaw

Impact of degenerative radiographic abnormalities and vertebral fractures on spinal bone density of women with osteoporosis

Paiva,Lúcia Costa; Filardi,Silvana; Pinto-Neto,Aarão Mendes; Samara,Adil; Marques Neto,João Francisco
Fonte: Associação Paulista de Medicina - APM Publicador: Associação Paulista de Medicina - APM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2002 EN
Relevância na Pesquisa
36.07%
CONTEXT: Measurements of bone density taken by dual-energy x-ray absorptiometry are the most accurate procedure for the diagnosis of osteoporosis. This procedure has the disadvantage of measuring the density of all mineral components, including osteophytes, vascular and extra vertebral calcifications. These alterations can influence bone density results and densitometry interpretation. OBJECTIVE: To correlate radiography and densitometry findings from women with osteoporosis, analyzing the influence of degenerative processes and vertebral fractures on the evaluation of bone density. DESIGN: Retrospective study. SETTING: Osteoporosis outpatients' clinic at Hospital das Clínicas, Universidade Estadual de Campinas. PARTICIPANTS: Ninety-six postmenopausal women presenting osteoporosis diagnosed by bone density. MAIN MEASUREMENTS: Bone mineral density of the lumbar spine and femoral neck were measured by the technique of dual-energy x-ray absorptiometry, using a LUNAR-DPX densitometer. Fractures, osteophytes and aortic calcifications were evaluated by simple x-rays of the thoracic and lumbar spine. RESULTS: The x-rays confirmed vertebral fractures in 41.6%, osteophytes in 33.3% and calcifications of the aorta in 30.2%. The prevalence of fractures and aortic calcifications increased with age. The mean bone mineral density was 0.783g/cm² and the mean T-score was --3.47 DP. Neither fractures nor aortic calcifications had significant influence on bone mineral density (P = 0.36 and P = 0.09...

A study of the relationship between the black and white solid ink density and image quality in lithography

Wu, Chia-Wei
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.04%
The purpose of this research is to determine the relationship between the solid ink density and image quality by application of an image quality scaling method. The results quantify the relationship between image quality and printed solid ink densities. Six different solid ink density prints were produced, including solid ink density 0.8, 1.0, 1.2, 1.4, 1.6 and 1. 8. A paired comparison evaluation procedure was used to determine which of solid ink density prints was the best in this experiment. The optimum tone reproduction corresponding to the solid ink density which produced the best possible image quality is shown by this experiment. The image quality appears linear from solid ink density 0.8 through 1.4. Above solid ink density 1.4 the image quality increases slightly and peaks at solid ink density 1. 6. The differences of image quality from solid ink density 1.4 through 1.8 are considered small as determined from the judgement in this experiment.

Predicting three-dimensional ocean density structure from remotely sensed surface observations

Grossi, Matthew
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
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36.05%
Oliver, Matthew J.; Knowing ocean density is essential to understanding ocean dynamics. Many processes are inuenced by ocean density structure, including geostrophic flow, heat transfer, acoustics, light refraction, the timing of phytoplankton blooms, nutrient pumping, water column mixing, and stability. In the ocean, density changes due to heat flux, wind mixing, and fresh water input. Biological responses such as phytoplankton abundance respond quickly to changes in density structure, although in non-conservative ways, because mixing often induces phytoplankton growth. Many of the environmental conditions that either drive (e.g., wind) or are driven by (e.g., phytoplankton) density are observable from remote sensing platforms. Therefore, the relationships between environmental conditions and density structure make it possible to use satellite observations to systematically predict subsurface density structure. In this study, I compiled over 300,000 density profiles from the Argo program, used nonlinear regression techniques to reduce them to five numeric parameters, and matched them with MODIS-Aqua sea surface temperature, normalized water leaving radiance at 412, 443, 488, 531, 551, and 667 nm, surface wind speeds from QuikSCAT...

Operational sex ratio and density do not affect directional selection on male sexual ornaments and behavior

Head, Megan; Lindholm, Anna K.; Brooks, Rob
Fonte: Society for the Study of Evolution Publicador: Society for the Study of Evolution
Tipo: Artigo de Revista Científica
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36.04%
Demographic parameters including operational sex ratio (OSR) and population density may influence the opportunity for, and strength of sexual selection. Traditionally, male-biased OSRs and high population densities have been thought to increase the opportunity for sexual selection on male sexual traits due to increased male competition for mates. Recent experimental evidence, however, suggests that male-biased OSRs might reduce the opportunity for sexual selection due to increased sexual coercion experienced by females. How OSR, density, and any resultant changes in the opportunity for sexual selection actually affect selection on male sexual traits is unclear. In this study, we independently manipulated OSR and density in the guppy (Poecilia reticulata) without altering the number of males present. We recorded male and female behavior and used DNA microsatellite data to assign paternity to offspring and estimate male reproductive success. We then used linear selection analyses to examine the effects of OSR and density on directional sexual selection on male behavioral and morphological traits. We found that females were pursued more by males in male-biased treatments, despite no change in individual male behavior. There were no differences in sexual behavior experienced by females or performed by males in relation to density. Neither OSR nor density significantly altered the opportunity for sexual selection. Also...