Página 1 dos resultados de 538 itens digitais encontrados em 0.024 segundos

‣ Homogeneity assessment of a station climate series (1933-2005) in the Metropolitan Area of Sao Paulo: instruments change and urbanization effects

Sugahara, Shigetoshi; da Rocha, Rosmeri Porfirio; Ynoue, Rita Yuri; da Silveira, Reinaldo Bomfim
Fonte: SPRINGER WIEN; WIEN Publicador: SPRINGER WIEN; WIEN
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.483826%
This work assessed homogeneity of the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG) weather station climate series, using various statistical techniques. The record from this target station is one of the longest in Brazil, having commenced in 1933 with observations of precipitation, and temperatures and other variables later in 1936. Thus, it is one of the few stations in Brazil with enough data for long-term climate variability and climate change studies. There is, however, a possibility that its data may have been contaminated by some artifacts over time. Admittedly, there was an intervention on the observations in 1958, with the replacement of instruments, for which the size of impact has not been yet evaluated. The station transformed in the course of time from rural to urban, and this may also have influenced homogeneity of the observations and makes the station less representative for climate studies over larger spatial scales. Homogeneity of the target station was assessed applying both absolute, or single station tests, and tests relatively to regional climate, in annual scale, regarding daily precipitation, relative humidity, maximum (TMax), minimum (TMin), and wet bulb temperatures. Among these quantities...

‣ A homogeneidade da rentabilidade bancária em relação a tamanho, origem de capital e operações de crédito; The banking profitability homogeneity in relation to size, kind of control and credit operation

Oliveira, Daniel Diniz
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 09/06/2008 Português
Relevância na Pesquisa
27.191763%
Nos últimos anos a sociedade brasileira tem criticado os lucros alcançados pelos bancos, por considerá-los excessivamente elevados. Tal situação tem, inclusive, incentivado medidas, por parte do governo federal, para proteger o consumidor em relação às tarifas e aos juros cobrados pelas instituições financeiras. Por sua vez, a sociedade parece enxergar o setor de forma homogênea, sem atentar para as diferenças existentes entre seus integrantes. Este estudo tem o intuito de explicitar eventuais diferenças, relativas à rentabilidade, existentes no setor, de forma a fomentar uma visão mais crítica e menos superficial do segmento bancário, podendo, eventualmente, contribuir na elaboração de políticas para o setor. Para tanto, avaliou-se a uniformidade dos resultados dos bancos em relação a origem de capital, tamanho e nível de operações de crédito, a partir de uma base de dados, que compreendeu o período entre 1996 e 2006. O intervalo de tempo total foi dividido em três partes, de 1996 a 1998, denominado 1º período; de 1999 a 2002, 2º período; e, de 2003 a 2006, 3º período. Com esta divisão é possível identificar alterações nas relações entre as categorias das variáveis de um período para outro...

‣ Interações entre a atmosfera e a superfície terrestre: variações da temperatura e umidade na bacia B do Núcleo Cunha (IF) - SP; Interactions between atmosphere and land surface: temperature and humidity variations in Basin B of Núcleo Cunha (IF) - SP

Armani, Gustavo
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 08/10/2004 Português
Relevância na Pesquisa
37.06412%
Os objetivos desta pesquisa são: a) compreender como a temperatura do ar e a umidade relativa na bacia B do Núcleo Cunha (IF) estão relacionadas aos controles climáticos (altitude, declividade e orientação das vertentes, vegetação, a configuração do céu, etc); b) entender qual a importância de cada controle climático nas variações de temperatura e umidade relativa sob a ação de diferentes sistemas atmosféricos. Os controles microclimáticos produzem alterações no ritmo da temperatura e da umidade relativa de diferentes formas e graus de importância em função do sistema atmosférico atuante. Entretanto, a combinação de controles climáticos específicos pode criar ambientes que mantém o ritmo da temperatura e umidade mais estável, independente do sistema atmosférico que estiver atuando. A água no solo desempenha um papel fundamental na minimização das variações da temperatura e da umidade em ambientes específicos. A vegetação também desempenha um papel importante no controle dos valores de umidade relativa, sendo mais relevante que a declividade e a orientação da vertente. As unidades climáticas da Bacia B foram delimitadas como síntese de todas as interações entre os atributos e controles climáticos. O conceito de unidade climática como um espaço onde a interação entre os atributos e controles climáticos tem uma certa homogeneidade...

‣ Porto Alegre, arquitetura e estilo - 1880 a 1930 -

Schäffer, Barbara
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
Português
Relevância na Pesquisa
26.88759%
O presente trabalho tem por objetivo o mapeamento analítico de exemplares da arquitetura de Porto Alegre no período 1880-1930, caracterizado pelo predomínio do ecletismo. Devido à multiplicidade de linguagens arquitetônicas, este período contrasta fortemente com a relativa homogeneidade da arquitetura anterior, na cidade, representada pela arquitetura colonial portuguesa, até 1822, e pelo neoclassicismo, durante o período imperial. O trabalho tem por marco temporal um período no qual a cidade deixa de exibir tal homogeneidade, iniciando em 1880 e seguindo até as últimas manifestações da arquitetura eclética. Ao longo do período, são identificados estilos arquitetônicos predominantes nas edificações eruditas e de maior porte. Cada estilo é abordado num capítulo deste trabalho. A elaboração textual de cada capítulo segue uma mesma organização: é redigida uma contextualização da manifestação do estilo no âmbito internacional, nacional e regional; são identificadas as ocorrências deste estilo nas edificações de Porto Alegre, nas quais haja predominância das características descritas; e, por fim, é feita a análise de algumas obras. As análises feitas e apresentadas neste trabalho dão ênfase à observação da edificação quanto a sua volumetria e ornamentação...

‣ Homogeneity assessment of a station climate series (1933-2005) in the Metropolitan Area of São Paulo: instruments change and urbanization effects

Sugahara, Shigetoshi; da Rocha, Rosmeri Porfirio; Ynoue, Rita Yuri; da Silveira, Reinaldo Bomfim
Fonte: Springer Wien Publicador: Springer Wien
Tipo: Artigo de Revista Científica Formato: 361-374
Português
Relevância na Pesquisa
27.483826%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); This work assessed homogeneity of the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG) weather station climate series, using various statistical techniques. The record from this target station is one of the longest in Brazil, having commenced in 1933 with observations of precipitation, and temperatures and other variables later in 1936. Thus, it is one of the few stations in Brazil with enough data for long-term climate variability and climate change studies. There is, however, a possibility that its data may have been contaminated by some artifacts over time. Admittedly, there was an intervention on the observations in 1958, with the replacement of instruments, for which the size of impact has not been yet evaluated. The station transformed in the course of time from rural to urban, and this may also have influenced homogeneity of the observations and makes the station less representative for climate studies over larger spatial scales. Homogeneity of the target station was assessed applying both absolute, or single station tests, and tests relatively to regional climate, in annual scale...

‣ Asymmetries in the perception of others as a function of social position and context

Cabecinhas, Rosa; Amâncio, Lígia
Fonte: Verlag Hans Huber Publicador: Verlag Hans Huber
Tipo: Artigo de Revista Científica
Publicado em //1999 Português
Relevância na Pesquisa
27.075889%
In the two experiments reported here an adaptation of the paradigm developed by Taylor, Fiske, Etcoff, & Ruderman (1978) was used to investigate: a) the impact of contextual factors on the accentuation effect, and b) asymmetries in the outgroup homogeneity effect as a function of relative group status. In both experiments targets were categorized on the basis of highly salient physical features, which also evoke asymmetric positions in intergroup relations: color of the skin in experiment 1 and sex in experiment 2. In experiment 1, with black and white participants, context was manipulated by introducing topics of discussion which were relevant (interethnic relations) and irrelevant (student university life) to the categorization, whereas in experiment 2, with female and male participants, the relevant topic of discussion was dating relationships and the irrelevant one was the same as in the previous experiment. According to our results, the accentuation effect was affected by context in experiment 1, but not in experiment 2, and the outgroup homogeneity effect was not symmetrical. Overall, target members of subordinate groups, blacks in experiment 1 and females in experiment 2, were more homogenized than target members of dominant groups...

‣ Enviesamentos na percepção dos grupos sociais : O papel da posição social e do contexto

Cabecinhas, Rosa
Fonte: ISPA - Instituto Superior de Psicologia Aplicada Publicador: ISPA - Instituto Superior de Psicologia Aplicada
Tipo: Artigo de Revista Científica
Publicado em //1996 Português
Relevância na Pesquisa
26.88759%
Neste artigo apresentamos dois estudos experi-- mentais realizados com o objectivo de verificar se o estatuto relativo dos grupos constitui um factor moderador na percepção do grupo de pertença e do grupo dos outros. Estes estudos consistiram em versões adaptadas do paradigma experimental de Taylor, Fiske, Etcoff e Ruderman (1978) em situações de saliência dos critérios de categorização racial (Estudo 1) e sexual (Estudo 2). Os resultados evidenciam uma manifestação assimétrica do efeito de homogeneidade do outgroup: globalmente, os sujeitos-estímulo dos grupos «dominados)) (negros no Estudo 1 e mulheres no Estudo 2) são mais homogeneizados do que os sujeitos- -estímulo dos grupos «dominantes» (brancos no Estudo 1 e homens no Estudo 2). Na discussão dos resultados salientamos a insuficiência dos modelos puramente cognitivos na análise dos enviesamentos que ocorrem na percepção dos grupos sociais e a pertinência do nível de análise ideológico na explicação dos mesmos.; RESUME------Cet article présente deux études expérimentales entreprises avec l’objectif de vérifier si le statut relative des groupes constitue un facteur modérateur de la perception du endogroupe et du exogroupe. Ces études s’appuient sur des versions adaptées du paradigme expérimental de Taylor...

‣ Crystallinity and microchemistry of Nassarius reticulatus (Caenogastropoda) statoliths : towards their structure stability and homogeneity

Oliveira, Susana Galante; Marçal, Raquel; Guimarães, Fernanda M. G.; Soares, Jorge; Lopes, José Carlos; Machado, Jorge; Barroso, Carlos
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Artigo de Revista Científica
Publicado em /05/2014 Português
Relevância na Pesquisa
37.270261%
Gastropod statoliths are spherical biocarbonates formed during their lifespan. The stability and homogeneity of these structures’ mineral matrix was characterised along their radiuses, using Nassarius reticulatus as a model. Generally, they were proved to be bimineralic. Two of the three CaCO3 crystalline polymorphs occurring in biocarbonates – aragonite and calcite – coexist along statolith radiuses, aragonite being unequivocally the most abundant phase. The presence of a diffuse organic matrix was also perceived by the detection of a weak Raman band between 2800 and 3000 cm-1 consistently observed along radiuses. Beyond the apparent stability and homogeneity, different crystalline orientations were disclosed by Raman spectroscopy. A change in the intensity pattern of the features related to the lattice and bending modes of aragonite between different radiuses give new insights for a possible spherulitic-like growth of these structures. As expected from the relative homogeneity of both mineral and organic signals, there was no pattern on the distribution of Ca, O, Na and S along radiuses. However, a higher concentration of Sr occurs in growth rings (known as winter tags), corroborating the already described negative correlation between the concentration of this element in statoliths and temperature. Despite the apparent stability and homogeneity of the matrix during its lifespan...

‣ Differential Selection of Specific Human Immunodeficiency Virus Type 1/JC499 Variants after Mucosal and Parenteral Inoculation of Chimpanzees

Wei, Qing; Fultz, Patricia N.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /01/2002 Português
Relevância na Pesquisa
26.88759%
Regardless of the route of transmission, it is generally accepted that the human immunodeficiency virus type 1 (HIV-1) quasispecies transmitted from an infected individual to an uninfected individual is genetically homogeneous. This finding and the observation that HIV-1 genotypes in recipients are minor variants in the donors suggest strongly that selection for specific variants occurs. However, most analyses have been limited to the V3 region of env. In addition, the exact time at which most new infections occurred was not known, making it almost impossible to analyze virus populations present in donor-recipient pairs at the time of HIV-1 transmission. To circumvent this problem, three chimpanzees were inoculated with a genetically defined stock of cell-free HIV-1/JC499 by one of three routes: intravenously or via the cervical or penile mucosa. PCR products of the C2-to-V5 region of env were amplified from both proviral DNA and virion RNA in blood samples collected soon after infection and were screened by heteroduplex analysis (HDA). Those PCR products with distinct HDA banding patterns were cloned and sequenced. In all three animals, transmitted variants encoded one of two V3-loop populations identified in the inoculum, indicating relative homogeneity in this region. However...

‣ Purification to homogeneity of Charonia lampas alpha-fucosidase by using sequential ligand-affinity chromatography.

Butters, T D; Scudder, P; Rotsaert, J; Petursson, S; Fleet, G W; Willenbrock, F W; Jacob, G S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/10/1991 Português
Relevância na Pesquisa
26.88759%
An alpha-fucosidase from the liver of the marine gastropod Charonia lampas was purified to homogeneity using a procedure that included cation-exchange and gel-filtration chromatography, chromatofocusing and a final series of affinity-chromatography steps which involved the following gel-immobilized ligands: N-(5-carboxy-1-pentyl)-1,5-dideoxy-1,5-imino-L-fucitol, N-(5-carboxy-1-pentyl)-2-acetamido-1,5-imino-1,2,5-trideoxy-D-glucitol and thio-beta-D-galactoside. The enzyme was found to be a tetrameric glycoprotein with a native Mr of 208,000, and to exist in a number of isoforms displaying pI values in the range 6.0-6.4. Substrate-specificity studies using a number of fucosylated oligosaccharides of the lacto-N and lacto-N-neo series and a synthetic disaccharide confirmed that the enzyme catalyses the hydrolysis of a broad range of fucosidic linkages, and established the following hierarchy of susceptibility: Fuc alpha 2Gal beta 4Glc much much greater than Fuc alpha 6GlcNAc greater than Fuc alpha 2Gal beta 4GlcNAc greater than Gal beta 3(Fuc alpha 4)GlcNAC much much greater than Gal beta 4(Fuc alpha 3)GlcNAc. Similar relative rates of hydrolysis were also demonstrated using biantennary oligosaccharide alditols as substrates which contained fucose linked either alpha 3 or alpha 6 to the N-acetylglucosaminitol residue of the chitobiosyl core.

‣ Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Ieukoencephalopathy, Genetic Homogeneity, and Mapping of the Locus within a 2-cM Interval

Ducros, A.; Nagy, T.; Alamowitch, S.; Nibbio, A.; Joutel, A.; Vahedi, K.; Chabriat, H.; Iba-Zizen, M. T.; Julien, J.; Davous, P.; Goas, J. Y.; Lyon-Caen, O.; Dubois, B.; Ducrocq, X.; Salsa, F.; Ragno, M.; Burkhard, P.; Bassetti, C.; Hutchinson, M.; Vérin
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1996 Português
Relevância na Pesquisa
26.88759%
Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a recently identified autosomal dominant cerebral arteriopathy characterized by the recurrence of subcortical infarcts leading to dementia. A genetic linkage analysis conducted in two large families recently allowed us to map the affected gene on chromosome 19 in a 12-cM interval bracketed by D19S221 and D19S215. In the present study, these first 2 families and 13 additional ones, including a total of 199 potentially informative meiosis, have been genotyped with eight polymorphic markers located between D19S221 and D19S215. All families were linked to chromosome 19. The highest combined lod score (Zmax = 37.24 at θ = .01) was obtained with marker D19S841, a new CAn microsatellite marker that we isolated from chromosome 19 cosmids. The recombinant events observed within these families were used to refine the genetic mapping of CADASIL within a 2-cM interval that is now bracketed by D19S226 and D19S199 on 19pl3.1. These data strongly suggest the genetic homogeneity of this recently identified condition and establish the value of its clinical and neuroimaging diagnostic criteria. Besides their importance for the ongoing positional cloning of the CADASIL gene...

‣ The buffer barrier hypothesis, [Ca2+]i homogeneity, and sarcoplasmic reticulum function in swine carotid artery

Rembold, Christopher M; Chen, Xiao-Liang
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
Publicado em 01/12/1998 Português
Relevância na Pesquisa
27.075889%
The goal of this study was to evaluate the buffer barrier hypothesis in an intact arterial smooth muscle. Specifically, we investigated the interrelationships between intracellular [Ca2+] ([Ca2+]i) homogeneity and sarcoplasmic reticulum function in swine carotid artery.We measured focal changes in [Ca2+]i by exploiting the different characteristics of several [Ca2+]i indicators: (1) aequorin, which can detect focal increases in [Ca2+]i such as those that occur in the subplasmalemmal region ([Ca2+]pm); (2) fura-2, which is primarily a measure of mean cytoplasmic [Ca2+] ([Ca2+]c); and (3) force, which reflects increases in [Ca2+] near the contractile apparatus. We then estimated the relative degree of [Ca2+]i homogeneity with the aequorin/fura-2 ratio. Finally, we inhibited sarcoplasmic reticulum Ca2+ pumping with cyclopiazonic acid (CPA), an inhibitor of the sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA).We found that, after Ca2+ depletion, the sarcoplasmic reticulum could be partially reloaded with Ca2+ by manipulations that increased the aequorin signal relatively more than the fura-2 signal. Complete reloading required large increases in the fura-2 signal. These data suggest that increases in [Ca2+]pm (as measured with aequorin) can partially reload the sarcoplasmic reticulum...

‣ An??lise harm??nica dos totais de chuvas mensais de regi??es homog??neas do Estado do Rio Grande do Sul; Harmonic analysis of the total rainfall monthly of homogeneous regions of the state of Rio Grande do Sul

CARDOSO, Daniel Souza
Fonte: Universidade Federal de Pelotas; Meteorologia; Programa de P??s-gradua????o em Meteorologia; UFPel; BR Publicador: Universidade Federal de Pelotas; Meteorologia; Programa de P??s-gradua????o em Meteorologia; UFPel; BR
Tipo: Dissertação Formato: application/pdf
Português
Relevância na Pesquisa
27.191763%
Whereas the State of Rio Grande do Sul (RS), have an economy directly dependent on agriculture and livestock sectors, which in different studies are reported as dependent on the variability of certain climatological elements, and the RS element water is regarded as fundamental. We conducted a study of the monthly total rainfall, to long 60 years (1948/2007), collected from 31 meteorological stations (EMs) and distributed geographically in the state. In the interest of contributing to the local society to predict possible shortages, and / or development of public policies for the use of water resources in urban and rural areas. In order to obtain a model that can provide an approximation of the behavior of the average rainfall for each of the six homogeneous regions, as defined in the literature (Marques, 2005), held has an harmonic analysis of the data previously adjusted to 30-day months. Before the analisys, the properties were checked for normality, homogeneity of variance and stationarity. The data tested for normality and homogeneity of variances, have not passed satisfactory in these tests and, hence, there was a transformation of data, generating new data sets that met the conditions of homogeneity of variance and normality. The relative increase in the trend...

‣ Homogeneity and heterogeneity of political traditions in the remaking of world order

Schiele, Alexandre
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
Português
Relevância na Pesquisa
27.101155%
Deux décennies après la chute de l'URSS (1991), ce mémoire propose une réévaluation de la thèse de Francis Fukuyama sur la Fin de l'Histoire, élaborée en 1989, qui postule qu'avec la chute de l'URSS aucune idéologie ne peut rivaliser avec la démocratie libérale capitaliste; et de la thèse de Samuel P. Huntington sur le Choc des civilisations, élaborée en 1993, qui pose l'existence d'un nombre fini de civilisations homogènes et antagonistes. Pourtant, lorsque confrontées à une étude approfondie des séquences historiques, ces deux théories apparaissent pour le moins relatives. Deux questions ont été traitées: l'interaction entre Idéologie et Conditions historiques, et la thèse de l'homogénéité intracivilisationnelle et de l'hétérogénéité antagoniste intercivilisationnelle. Sans les invalider complètement, cette recherche conclut toutefois que ces deux théories doivent être nuancées; elles se situent aux deux extrémités du spectre des relations internationales. La recherche effectuée a montré que les idéologies et leur poids relatif sont tributaires d'un contexte, contrairement à Fukuyama qui les pose dans l'absolu. De plus, l'étude de la Chine maoïste et particulièrement de la pensée de Mao Zedong montre que les traditions politiques locales sont plus hétérogènes qu'il n'y paraît au premier abord...

‣ All-sky homogeneity of precipitable water vapour over Paranal

Querel, Richard R.; Kerber, Florian
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 07/08/2014 Português
Relevância na Pesquisa
27.191763%
A Low Humidity and Temperature Profiling (LHATPRO) microwave radiometer, manufactured by Radiometer Physics GmbH (RPG), is used to monitor sky conditions over ESO's Paranal observatory in support of VLT science operations. The unit measures several channels across the strong water vapour emission line at 183 GHz, necessary for resolving the low levels of precipitable water vapour (PWV) that are prevalent on Paranal (median ~2.4 mm). The instrument consists of a humidity profiler (183-191 GHz), a temperature profiler (51-58 GHz), and an infrared camera (~10 {\mu}m) for cloud detection. We present, for the first time, a statistical analysis of the homogeneity of all-sky PWV using 21 months of periodic (every 6 hours) all-sky scans from the radiometer. These data provide unique insight into the spatial and temporal variation of atmospheric conditions relevant for astronomical observations, particularly in the infrared. We find the PWV over Paranal to be remarkably homogeneous across the sky down to 27.5{\deg} elevation with a median variation of 0.32 mm (peak to valley) or 0.07 mm (rms). The homogeneity is a function of the absolute PWV but the relative variation is fairly constant at 10-15% (peak to valley) and 3% (rms). Such variations will not be a significant issue for analysis of astronomical data. Users at ESO can specify PWV - measured at zenith - as an ambient constraint in service mode to enable...

‣ The Differential Geometry of Homogeneity Spaces Across Effect Scales

Ding, Peng; VanderWeele, Tyler J.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.403364%
If an effect measure is more homogeneous than others, then its value is more likely to be stable across different subgroups or subpopulations. Therefore, it is of great importance to find a more homogeneous effect measure that allows for transportability of research results. For a binary outcome, applied researchers often claim that the risk difference is more heterogeneous than the risk ratio or odds ratio, because they find, based on evidence from surveys of meta-analyses, that the null hypotheses of homogeneity are rejected more often for the risk difference than for the risk ratio and odds ratio. However, the evidence for these claims are far from satisfactory, because of different statistical powers of the homogeneity tests under different effect scales. For binary treatment, covariate and outcome, we theoretically quantify the homogeneity of different effect scales. Because when homogeneity holds the four outcome probabilities lie in a three dimensional sub-space of the four dimensional space, we can use results from differential geometry to compute the volumes of these three dimensional spaces to compare the relative homogeneity of the risk difference, risk ratio, and odds ratio. We demonstrate that the homogeneity space for the risk difference has the smallest volume...

‣ Millennium Simulation Dark Matter Haloes: Multi-fractal and Lacunarity Analysis with Homogeneity Transition

Chacón-Cardona, César A.; Casas-Miranda, Rigoberto A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 12/09/2012 Português
Relevância na Pesquisa
27.075889%
We investigate from the fractal viewpoint the way in which the dark matter is grouped at z = 0 in the Millennium dark matter cosmological simulation. The determination of the cross to homogeneity in the Millennium Simulation data is described from the behaviour of the fractal dimension and the lacunarity. We use the sliding window technique to calculate the fractal mass-radius dimension, the pre-factor F and the lacunarity of this fractal relation. Besides, we determinate the multi-fractal dimension and the lacunarity spectrum, including their dependence with radial distance. This calculations show a radial distance dependency of all the fractal quantities, with heterogeneity clustering of dark matter haloes up to depths of 100 Mpc/h. The dark matter haloes clustering in the Millennium Simulation shows a radial distance dependency, with two regions clearly defined. The lacunarity spectrum for values of the structure parameter q >= 1 shows regions with relative maxima, revealing the formation of clusters and voids in the dark matter haloes distribution. With the use of the multi-fractal dimension and the lacunarity spectrum, the transition to homogeneity at depths between 100 Mpc/h and 120 Mpc/h for the Millennium Simulation dark matter haloes is detected.; Comment: 13 pages...

‣ Relative Density-Ratio Estimation for Robust Distribution Comparison

Yamada, Makoto; Suzuki, Taiji; Kanamori, Takafumi; Hachiya, Hirotaka; Sugiyama, Masashi
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 23/06/2011 Português
Relevância na Pesquisa
26.922388%
Divergence estimators based on direct approximation of density-ratios without going through separate approximation of numerator and denominator densities have been successfully applied to machine learning tasks that involve distribution comparison such as outlier detection, transfer learning, and two-sample homogeneity test. However, since density-ratio functions often possess high fluctuation, divergence estimation is still a challenging task in practice. In this paper, we propose to use relative divergences for distribution comparison, which involves approximation of relative density-ratios. Since relative density-ratios are always smoother than corresponding ordinary density-ratios, our proposed method is favorable in terms of the non-parametric convergence speed. Furthermore, we show that the proposed divergence estimator has asymptotic variance independent of the model complexity under a parametric setup, implying that the proposed estimator hardly overfits even with complex models. Through experiments, we demonstrate the usefulness of the proposed approach.

‣ Testing Slope Homogeneity in Large Panels

Pesaran, M. Hashem; Yamagata, Takashi
Fonte: Universidade de Cambridge Publicador: Universidade de Cambridge
Formato: 314223 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
37.517197%
This paper proposes a modified version of Swamy?s test of slope homogeneity for panel data models where the cross section dimension (N) could be large relative to the time series dimension (T). We exploit the cross section dispersion of individual slopes weighted by their relative precision. Using Monte Carlo experiments, we show that the test has the correct size and satisfactory power in panels with strictly exogenous regressors for various combinations of N and T. For autoregressive (AR) models the test performs well for moderate values of the root of the autoregressive process, but with roots near unity a bias-corrected bootstrapped version performs well even if N is large relative to T. The cross section dispersion tests are used to test the homogeneity of slopes in autoregressive models of individual earnings using the PSID data and show statistically significant evidence of slope heterogeneity in the earnings dynamics.

‣ The relative homogeneity of microbial DNA

Rolfe, Ronald; Meselson, Matthew
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em /07/1959 Português
Relevância na Pesquisa
37.075889%
Density-gradient centrifugation has revealed that the population of DNA molecules from E. coli is relatively homogeneous with respect to buoyant density in a solution of cesium chloride.(1) Because of the notably small apparent atomic volume of nitrogen in aqueous solutions of organic compounds(2) and because the guanine-cytosine base pair is more rich in nitrogen than is the adenine-thymine pair, it was considered that the density homogeneity among E. coli DNA molecules might reflect a high degree of homogeneity with respect to base composition. To investigate this possibility, an examination has been made of the relationship between buoyant density in cesium chloride solution and base composition of DNA from various sources.