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Comportamento de misturas binarias lipidicas na produção de microparticulas por spray chilling e sua influencia na liberação de recheio hidrofilico; Behavior of binary lipid in the production of microparticles by spray chilling and its influence on the hydrophilic core release

Marilene De Mori Morselli Ribeiro
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 25/02/2010 PT
Relevância na Pesquisa
35.77%
A facilidade de obtenção de micropartículas lipídicas e a possibilidade de produção em escala industrial aumentam o interesse do mercado alimentício de processar este tipo de material. Contudo, estas micropartículas apresentam desvantagens com relação à baixa encapsulação e à expulsão de material de recheio durante a estocagem. Assim, a finalidade deste trabalho foi estudar o comportamento das microcápsulas lipídicas produzidas pelo processo spray chilling utilizando as seguintes misturas em diferentes proporções: ácidos esteárico (AE) e oléico (AO), óleo de soja totalmente hidrogenado (STH) e ácido oléico (AO), álcool cetoestearílico (ACE) e ácido oléico (AO) como materiais de parede (matriz), lecitina de soja como tensoativo e solução de glicose como recheio. O objetivo foi aumentar a eficiência de encapsulação, verificando o efeito da composição e estrutura da matriz lipídica. Para este propósito, foram caracterizadas as matérias-primas lipídicas em composição de ácidos graxos e triacilgliceróis, bem como, as misturas lipídicas avaliadas por calorimetria diferencial de varredura (DSC), teor de gordura sólida (SFC) e curva de isosólidos. Nas micropartículas, foram avaliadas morfologia de superfície e microestrutura...

Influência da granulometria do material inerte e da composição de misturas binárias contendo areia e partículas de bambu (in natura e carvão produto do processo pirolítico) sobre a fluidodinâmica de leitos fluidizados; Influence of the granulometry of tinert material and of the composition of binary mixtures containing sand and bamboo particles (in natura and coal from pyrolysis process) on the hydrodynamics of fluidized beds

Deyber Alexander Ramirez Quintero
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/02/2015 PT
Relevância na Pesquisa
35.9%
A aplicação de biomassas em processos de geração de energia como a combustão, pirólise e gaseificação, operando com a tecnologia de leito fluidizado, tem merecido atenção crescente nas últimas décadas. Esses sistemas necessitam da adição de partículas de material inerte que ajudam a promover uma fluidização estável, permitindo a melhoria da eficiência de tais processos. Dentre as biomassas com potencial para geração de energia sustentável está o bambu, material que apresenta propriedades semelhantes às de outras biomassas utilizadas em processos de geração de energia, com a vantagem de apresentar rápido crescimento, fácil propagação, regeneração vigorosa, maturidade rápida. O objetivo deste projeto foi estudar o comportamento fluidodinâmico de misturas de partículas de areia e bambu (in natura e na forma de carvão proveniente de processo de pirólise) visando à obtenção de parâmetros inerentes à fluidização dessas misturas, bem como analisar o efeito da degradação térmica da partícula de bambu sobre a fluidização do leito. A análise foi realizada a partir do levantamento experimental da curva fluidodinâmica em sistema de leito fluidizado operando a frio, com diferentes composições das misturas bambu-areia e carvão-areia. Adicionalmente foi verificada a influência do tamanho das partículas de areia e da altura estática do leito sobre a fluidodinâmica do leito. Os resultados mostraram que a melhor qualidade da fluidização do leito contendo partículas de bambu in natura foi obtida usando a areia identificada como areia 3 (diâmetro médio de 460 µm)...

Application of binary packing for chromatographic separation

Mota, M.; Teixeira, J. A.; Yelshin, Alexander; Dias, Ricardo P.; Cortez, Susana
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2005 ENG
Relevância na Pesquisa
35.96%
Separation of dextran and polyethylene glycol of different molecular mass was performed using a binary packed column of glass beads (size ratio ~ 10) and a binary packed column formed by kieselguhr-G (for thin layer chromatography, Merck) and glass beads as the large size particulate fraction (size ratio ~ 30). In addition, data on the separation of micro-spheres, bacillus and yeast cells using monosized and binary glass beads columns are presented. Obtained results show the advantages of using binary packed columns formed by fine and coarse particles instead of a monosize packing of fine particles. The importance of pore channels tortuosity effect on the separation of shaped microparticles using a binary packing is demonstrated.

Growth rate of Pseudokirchneriella subcapitata exposed to herbicides found in surface waters in the Alqueva reservoir (Portugal): a bottom-up approach using binary mixtures

Perez, J; Domingues, I; Soares, AMVM; Loureiro, S
Fonte: Springer Verlag Publicador: Springer Verlag
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
35.92%
Previous work showed the existence of ecotoxicity of water samples from the Alqueva reservoir due to the presence of the herbicides atrazine, simazine, terbuthylazine and metolachlor. In the present study we examine the effects of these herbicides singly and as binary mixtures on the growth rate of the microalgae Pseudokirchneriella subcapitata. Usually, the toxicity of mixtures is evaluated in relation to the reference models CA (concentration addiction) and IA (independent action). In this study CA model was selected to evaluate the joint effects of s-triazine herbicides on the growth of algae due to their similar mode of action. Moreover, IA reference model was chosen to evaluate the joint toxicity of the chloroacetanilide metolachlor and the s-triazine herbicides due to their different mode of action. In this study dose ratio was the common deviation obtained on both reference models. In the binary mixtures between atrazine/simazine and atrazine/terbuthylazine the increase of the mixtures toxicity (synergism) was mainly due to atrazine. Also, in the binary mixture between atrazine and metolachlor, atrazine was responsible for the increase (synergism) of the mixture toxicity. In the cases of the binary mixtures between simazine/metolachlor and terbuthylazine/metolachlor...

Effects of binary mixtures on the life traits of Daphnia magna

Pavlaki, MD; Pereira, R; Loureiro, S; Soares, AMVM
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
35.85%
The environment is constantly exposed to a cocktail of contaminants mainly due to human activities. Because polluted ecosystems are characterized by an amalgam of chemical compounds, the objective of the present study was to assess the joint effect of chemical mixtures to the life history traits of Daphnia magna Straus. For that a binary mixture of two neonicotinoid insecticides, imidacloprid and thiacloprid, and another one of imidacloprid with nickel chloride were tested. Theoretical models have been developed and applied in studies with chemical mixtures, predicting toxicity based on their modes of action: concentration addition (CA) and independent joint action (IA) models. Still there are cases where deviations are observed (e.g. synergistic or antagonistic behaviors, dose ratio or level dependency). In this study, the effects of the individual compounds and their mixtures were studied in a chronic test where reproduction, survival and body length were evaluated in D. magna. Regarding single compound effects, it was observed that the most toxic was nickel chloride followed by thiacloprid and imidacloprid. For the mixture exposure of imidacloprid and thiacloprid, a synergistic pattern was observed in the sublethal doses used for the number of neonates produced...

Toxicity of three binary mixtures to Daphnia Magna: comparing chemical modes of action and deviations from conceptual models

Loureiro, S; Svendsen, C; Ferreira, ALG; Pinheiro, C; Ribeiro, F; Soares, AMVM
Fonte: SETAC Press Publicador: SETAC Press
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
35.85%
Complex mixtures makes the assessment of environmental hazards difficult due to possible antagonistic or synergistic interactions that can occur between chemicals, or even more complex effect patterns like dose-level or dose-ratio dependent responses. The aim of the present work was to investigate the acute and sublethal responses of Daphnia magna Straus exposed to four single chemical compounds (imidacloprid, thiacloprid, nickel chloride, and chlorpyrifos) and three binary chemical mixtures. In the immobilization and feeding inhibition bioassays, chlorpyrifos was the most toxic to D. magna, followed by nickel chloride, and imidacloprid and thiacloprid, which showed similar levels of toxicity. The MIXTOX was used to evaluate mixture toxicity. Observed data was compared with the expected mixture effects predicted by concentration addition (CA) and independent action (IA) models; deviations for synergistic/antagonistic interactions, dose-level and dose-ratio dependency were also used. In the mixture toxicity assessment, several patterns of response were obtained depending on the mixture but also on the endpoint tested. For imidacloprid and thiacloprid, deviations for synergism were observed in acute exposures (immobilization), and antagonism for feeding rates at sublethal concentrations. For imidacloprid and chlorpyrifos...

A correlation between lipid domain shape and binary phospholipid mixture composition in free standing bilayers: A two-photon fluorescence microscopy study.

Bagatolli, L A; Gratton, E
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/2000 EN
Relevância na Pesquisa
26.01%
Giant unilamellar vesicles (GUVs) composed of different phospholipid binary mixtures were studied at different temperatures, by a method combining the sectioning capability of the two-photon excitation fluorescence microscope and the partition and spectral properties of 6-dodecanoyl-2-dimethylamino-naphthalene (Laurdan) and Lissamine rhodamine B 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (N-Rh-DPPE). We analyzed and compared fluorescence images of GUVs composed of 1,2-dilauroyl-sn-glycero-3-phosphocholine/1, 2-dipalmitoyl-sn-glycero-3-phosphocholine (DLPC/DPPC), 1, 2-dilauroyl-sn-glycero-3-phosphocholine/1, 2-distearoyl-sn-glycero-3-phosphocholine (DLPC/DSPC), 1, 2-dilauroyl-sn-glycero-3-phosphocholine/1, 2-diarachidoyl-sn-glycero-3-phosphocholine (DLPC/DAPC), 1, 2-dimyristoyl-sn-glycero-3-phosphocholine/1, 2-distearoyl-sn-glycero-3-phosphocholine (DMPC/DSPC) (1:1 mol/mol in all cases), and 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine/1, 2-dimyristoyl-sn-glycero-3-phosphocholine (DMPE/DMPC) (7:3 mol/mol) at temperatures corresponding to the fluid phase and the fluid-solid phase coexistence. In addition, we studied the solid-solid temperature regime for the DMPC/DSPC and DMPE/DMPC mixtures. From the Laurdan intensity images the generalized polarization function (GP) was calculated at different temperatures to characterize the phase state of the lipid domains. We found a homogeneous fluorescence distribution in the GUV images at temperatures corresponding to the fluid region for all of the lipid mixtures. At temperatures corresponding to phase coexistence we observed concurrent fluid and solid domains in the GUVs independent of the lipid mixture. In all cases the lipid solid domains expanded and migrated around the vesicle surface as we decreased the temperature. The migration of the solid domains decreased dramatically at temperatures close to the solid-fluid-->solid phase transition. For the DLPC-containing mixtures...

Serial binary interval ratios improve rhythm reproduction

Wu, Xiang; Westanmo, Anders; Zhou, Liang; Pan, Junhao
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 06/08/2013 EN
Relevância na Pesquisa
25.99%
Musical rhythm perception is a natural human ability that involves complex cognitive processes. Rhythm refers to the organization of events in time, and musical rhythms have an underlying hierarchical metrical structure. The metrical structure induces the feeling of a beat and the extent to which a rhythm induces the feeling of a beat is referred to as its metrical strength. Binary ratios are the most frequent interval ratio in musical rhythms. Rhythms with hierarchical binary ratios are better discriminated and reproduced than rhythms with hierarchical non-binary ratios. However, it remains unclear whether a superiority of serial binary over non-binary ratios in rhythm perception and reproduction exists. In addition, how different types of serial ratios influence the metrical strength of rhythms remains to be elucidated. The present study investigated serial binary vs. non-binary ratios in a reproduction task. Rhythms formed with exclusively binary (1:2:4:8), non-binary integer (1:3:5:6), and non-integer (1:2.3:5.3:6.4) ratios were examined within a constant meter. The results showed that the 1:2:4:8 rhythm type was more accurately reproduced than the 1:3:5:6 and 1:2.3:5.3:6.4 rhythm types, and the 1:2.3:5.3:6.4 rhythm type was more accurately reproduced than the 1:3:5:6 rhythm type. Further analyses showed that reproduction performance was better predicted by the distribution pattern of event occurrences within an inter-beat interval...

Temporale und spektrale Untersuchungen des Röntgendoppelsternsystems Her X-1/HZ Herculis; A Study of Temporal and Spectral Behavior of the X-ray Binary System Her X-1/HZ Herculis

Risse, Marc Patrick
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
Relevância na Pesquisa
35.94%
30 Jahre sind seit der Entdeckung des Röntgendoppelsternsystems Her X-1/HZ Herculis durch den Satelliten UHURU vergangen. Mittlerweile gehört dieses Objekt neben Cyg X-1 zu den best untersuchten Objekten der Röntgenastronomie. Doch auch nach so vielen Jahren der Erforschung dieser Objekte gibt es immer noch zahlreiche Phänomene, die der Erklärung bedürfen. Zunächst werden in dieser Arbeit die Grundlagen der Astronomie im Allgemeinen und der Röntgendoppelsternsysteme im Speziellen erläutert (Kapitel 1). Anschließend wende ich mich der Beschreibung des Röntgendoppelsternsystems Her X-1/ HZ Her zu und fasse zusammen, was unser derzeitiger Stand des Wissens über dieses Objekt ist (Kapitel 2). In dieser Arbeit werden sowohl Beobachtungen von Röntgensatelliten als auch erdgebundene optische Beobachtungsdaten ausgewertet. Die aus dem Röntgenbereich analysierten Daten stammen von dem amerikanischen Röntgensatelliten RXTE (Rossi-X-Ray-Timing-Experiment). Die optischen Beobachtungsdaten wurden von unterschiedlichsten Arbeitsgruppen auf der ganzen Welt im Verlauf der letzten 27 Jahre gemacht. Diese enorme Datenbasis von fast 17000 Datenpunkten verteilt über vier Spektralbänder werden unter verschiedenen Gesichtspunkten in dieser Arbeit analysiert. Mittels der Röntgendaten wurden Untersuchungen über die Form des Pulses von Her X-1 vorgenommen. Dabei stellte ich eine Abweichung der Pulsform von der ansonsten bekannten fest. Nähere Untersuchungen ergaben...

"Uma aplicação industrial de regressão binária com erros na variável explicativa" ; "An industrial application of binary regression with errors-in-variable explanatory"

Favari, Daniel Fernando de
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 22/06/2006 PT
Relevância na Pesquisa
35.84%
Neste trabalho, aplicamos um modelo de regressão binária com erros de medição na variável explicativa para analisar sistemas de medição do tipo atributo. Para isto, utilizamos o modelo logístico com erros na variável, para o qual obtemos as estimativas de máxima verossimilhança via o algoritmo EM e a matriz de informação de Fisher observada. Além disso, fizemos um estudo de simulação para compararmos o método analítico e os modelos logístico sem erros na variável (ingênuo) e logístico com erros na variável. Finalmente, aplicamos nossa metodologia para avaliarmos um sistema de medição passa/não passa da maior montadora de motores Diesel (MWM International).; In this work, we apply a study of binary regression model with errors-in-variable to analyze attributive measurement systems. For this, we use the logistic model with errors-in-variable to obtain parameter estimates of maximum likelihood through EM algorithm and the observed Fisher information matrix. In addition we do a simulation study to compare analytic method and the logistic model with and without measurement errors-in-variable. Finally, we apply our methodology to evaluate a attributive measurement system for the largest Diesel motor company of the world (MWM International).

Comparison of lattice-fluid binary parameters for mixtures and block copolymers

Riccardi, Carmen Cristina; Schroeder, Walter Fabian; Serrano, Elena; Mondragon, Iñaki
Fonte: Taylor Publicador: Taylor
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
Relevância na Pesquisa
35.94%
The aim of this report is to discuss the method of determination of lattice-fluid binary interaction parameters by comparing well characterized immiscible blends and block copolymers of poly(methyl methacrylate) (PMMA) and poly(ε−caprolactone) (PCL). Experimental pressure-volume-temperature (PVT) data in the liquid state were correlated with the Sanchez-Lacombe (SL) equation of state with the scaling parameters for mixtures and copolymers obtained through combination rules of the characteristic parameters for the pure homopolymers. The lattice-fluid binary parameters for energy and volume were higher than those of block copolymers implying that the copolymers were more compatible due to the chemical links between the blocks. Therefore, a common parameter cannot account for both homopolymer blend and block copolymer phase behaviors based on current theory. As we were able to adjust all data of the mixtures with a single set of lattice-binary parameters and all data of the block copolymers with another single set we can conclude that both parameters did not depend on the composition for this system. This characteristic, plus the fact that the additivity law of specific volumes can be suitably applied for this system, allowed us to model the behavior of the immiscible blend with the SL equation of state. In addition...

The Matlab Vectorization Paradigm

Gaspar, Miguel; Martins-Ferreira, N.
Fonte: CDRSP-IPLeiria Publicador: CDRSP-IPLeiria
Tipo: Artigo de Revista Científica
Publicado em //2014 ENG
Relevância na Pesquisa
45.85%
We give two examples of application of a vectorized programming paradigm: binary addition and cycle decomposition of directed graphs.

Rotation Periods of Binary Asteroids with Large Separations - Confronting the Escaping Ejecta Binaries Model with Observations

Polishook, D.; Brosch, N.; Prialnik, D.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 21/12/2010
Relevância na Pesquisa
26.01%
Durda et al. (2004), using numerical models, suggested that binary asteroids with large separation, called Escaping Ejecta Binaries (EEBs), can be created by fragments ejected from a disruptive impact event. It is thought that six binary asteroids recently discovered might be EEBs because of the high separation between their components (~100 > a/Rp > ~20). However, the rotation periods of four out of the six objects measured by our group and others and presented here show that these suspected EEBs have fast rotation rates of 2.5 to 4 hours. Because of the small size of the components of these binary asteroids, linked with this fast spinning, we conclude that the rotational-fission mechanism, which is a result of the thermal YORP effect, is the most likely formation scenario. Moreover, scaling the YORP effect for these objects shows that its timescale is shorter than the estimated ages of the three relevant Hirayama families hosting these binary asteroids. Therefore, only the largest (D~19 km) suspected asteroid, (317) Roxane, could be, in fact, the only known EEB. In addition, our results confirm the triple nature of (3749) Balam by measuring mutual events on its lightcurve that match the orbital period of a nearby satellite in addition to its distant companion. Measurements of (1509) Esclangona at different apparitions show a unique shape of the lightcurve that might be explained by color variations.; Comment: 23 pages...

Evolution of the Binary Fraction in Dense Stellar Systems

Fregeau, J. M.; Ivanova, N.; Rasio, F. A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26%
Using our recently improved Monte Carlo evolution code, we study the evolution of the binary fraction in globular clusters. In agreement with previous N-body simulations, we find generally that the hard binary fraction in the core tends to increase with time over a range of initial cluster central densities for initial binary fractions <~ 90%. The dominant processes driving the evolution of the core binary fraction are mass segregation of binaries into the cluster core and preferential destruction of binaries there. On a global scale, these effects and the preferential tidal stripping of single stars tend to roughly balance, leading to overall cluster binary fractions that are roughly constant with time. Our findings suggest that the current hard binary fraction near the half-mass radius is a good indicator of the hard primordial binary fraction. However, the relationship between the true binary fraction and the fraction of main-sequence stars in binaries (which is typically what observers measure) is non-linear and rather complicated. We also consider the importance of soft binaries, which not only modify the evolution of the binary fraction, but can drastically change the evolution of the cluster as a whole. Finally, we describe in some detail the recent addition of single and binary stellar evolution to our cluster evolution code.; Comment: 8 pages...

Potential Importance of Binary Evolution in UV-Optical Spectral Fitting of Early-Type Galaxies

Li, Zhongmu; Mao, Caiyan; Chen, Li; Zhang, Qian; Li, Maocai
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 04/02/2013
Relevância na Pesquisa
25.99%
Binaries are very common in galaxies, and more than half of Galactic hot subdwarf stars, which are thought as a possible origin of UV-upturn of old stellar populations, are found in binaries. Previous works showed that binary evolution can make the spectra of binary star populations significantly different from those of single star populations. However, the effect of binary evolution has not been taken into account in most works of spectral fitting of galaxies. This paper studies the role of binary evolution in spectral fitting of early-type galaxies, via a stellar population synthesis model including both single and binary star populations. Spectra from ultraviolet to optical band are fitted to determine a few parameters of galaxies. The results show that the inclusion of binaries in stellar population models may lead to obvious change in the determination of some galaxy parameters and therefore it is potentially important for spectral studies. In particular, the ages of young components of composite stellar populations become much older when using binary star population models instead of single star population models. This implies that binary star population models will measure significantly different star formation histories (SFHs) for galaxies compared to single star population models. In addition...

On the Astrometric Behavior of Binary Microlensing Events

Han, Cheongho
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.06%
Despite the suspected binarity for a significant fraction of Galactic lenses, the current photometric surveys detected binary microlensing events only for a small fraction of the total events. The detection efficiency is especially low for non-caustic crossing events, which comprise majority of the binary lensing events, due to the absence of distinctive features in their light curves combined with small deviations from the standard light curve of a single point-mass event. In addition, even they are detected, it will be difficult to determine the solution of the binary lens parameters due to the severe degeneracy problem. In this paper, we investigate the properties of binary lensing events expected when they are astrometrically observed by using high precision interferometers. For this, we construct vector field maps of excess centroid shifts, which represent the deviations of the binary lensing centroid shifts from those of a single lensing events as a function of source position. From the analysis of the maps, we find that the excess centroid shifts are substantial in a considerably large area around caustics. In addition, they have characteristic sizes and directions depending strongly on the source positions with respect to the caustics and the resulting trajectories of the light centroid (astrometric trajectories) have distinctive features...

VLTI/AMBER observations of the binary B[e] supergiant HD 327083

Wheelwright, H. E.; de Wit, W. J.; Oudmaijer, R. D.; Vink, J. S.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.03%
HD 327083 is a luminous B type star which exhibits emission lines and an infrared excess and is therefore classified as a supergiant B[e] star. In addition, the star is the primary of a close binary system. It is not clear whether the B[e] behaviour of HD 327083 is related to its binarity or its evolutionary state. Here we address this issue by studying its circumstellar environment with high spatial resolution. To this end, we have observed HD 327083 with the VLTI and AMBER in the medium resolution K-band setting. 13CO bandhead emission is detected, confirming HD 327083 is a post-main sequence object. The observations spatially resolve the source of the NIR continuum and the Br-gamma and CO line emission. In addition, differential phase measurements allow us to probe the origin of the observed Br-gamma emission with sub-mas precision. Using geometrical models, we find that the visibilities and closure phases suggest that the close binary system is surrounded by a circum-binary disk. We also find that in the case of the binary HD 327083, the relative sizes of the continuum and Br-gamma emitting regions are different to those of a single supergiant B[e] star where the standard dual outflow scenario is thought to apply. These findings are consistent with the hypothesis that the mass loss of HD 327083 is related to its binary nature.; Comment: Accepted in A&A

Reduction from cost-sensitive ordinal ranking to weighted binary classification

Lin, Hsuan-Tien; Li, Ling
Fonte: Massachusetts Institute of Technology Press Publicador: Massachusetts Institute of Technology Press
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em /05/2012
Relevância na Pesquisa
26.06%
We present a reduction framework from ordinal ranking to binary classification. The framework consists of three steps: extracting extended examples from the original examples, learning a binary classifier on the extended examples with any binary classification algorithm, and constructing a ranker from the binary classifier. Based on the framework, we show that a weighted 0/1 loss of the binary classifier upper-bounds the mislabeling cost of the ranker, both error-wise and regret-wise. Our framework allows not only the design of good ordinal ranking algorithms based on well-tuned binary classification approaches, but also the derivation of new generalization bounds for ordinal ranking from known bounds for binary classification. In addition, our framework unifies many existing ordinal ranking algorithms, such as perceptron ranking and support vector ordinal regression. When compared empirically on benchmark data sets, some of our newly designed algorithms enjoy advantages in terms of both training speed and generalization performance over existing algorithms. In addition, the newly designed algorithms lead to better cost-sensitive ordinal ranking performance, as well as improved listwise ranking performance.

The Habitability and Stability of Earth-Like Planets in Binary Star Systems

Troup, Nicholas
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.01%
John E. Gizis; In 2011, NASA's Kepler spacecraft observed the first planet to be detected in a known binary star system, Kepler 16-b. Its discovery has sparked new discussion on the potential of binary systems supporting habitable Earth-like planets. In this study, by using relatively simple computation models, we are able to shed new light and place new limitations on this discussion. Habitable Zone geometry in binary systems is discussed as a part of this study, in which we are able to classify binary habitable zones into two major classes of merged and unmerged, with important special cases of each class presented. We were able to learn a good deal about the behavior of planets in S-type binary orbits, and the possibility of life on those planets. The effect of the orbit of the planet on the climate as well as how the planet experiences day and night are discussed, and we also present a lower limit for the binary separation at which a binary system would fail to have a habitable S-type orbit. In addition, we explore the possibility that a planet could remain habitable in a transfer orbit between the system's two stars or in orbit around one of the system's Lagrange Points. In this endeavor, we derive an analytical expression for the surface temperature of an Earth-like planet at a binary system's stable L4 and L5 Lagrange Points...

Application of the palladium[0]-catalysed Ullmann cross-coupling reaction in a total synthesis of (±)-aspidospermidine and thus representing an approach to the lower hemisphere of the binary indole-indoline alkaloid vinblastine

Banwell, Martin; Lupton, David; Willis, Anthony
Fonte: CSIRO Publishing Publicador: CSIRO Publishing
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.77%
As part of ongoing studies directed towards the construction of the anti-cancer agent vinblastine (1), the related but structurally less complex natural product aspidospermidine (3) has been synthesized. Two approaches to target 3 were pursued. In the first, which was unsuccessful, the amine-tethered enone 6 was prepared but this failed to engage in the pivotal intramolecular conjugate addition reaction to give the bicyclic system 5. In contrast, the related compound 46, incorporating tethered enone and azide moieties, engaged in an intramolecular 1,3-dipolar cycloaddition reaction to give, presumably via an intermediate triazoline, the isolable and ring-fused aziridine 47. This was then converted, over two steps, into the previously reported tetrahydrocarbazole 4. Application of established protocols to this last compound allowed for the installation of the E-ring of the title alkaloid 3 and completion of the total synthesis.