A global geometric framework for nonlinear dimensionality reduction   总被引：14，自引：0，他引：14  

Tenenbaum JB  de Silva V  Langford JC 《Science (New York, N.Y.)》2000,290(5500):2319-2323

Scientists working with large volumes of high-dimensional data, such as global climate patterns, stellar spectra, or human gene distributions, regularly confront the problem of dimensionality reduction: finding meaningful low-dimensional structures hidden in their high-dimensional observations. The human brain confronts the same problem in everyday perception, extracting from its high-dimensional sensory inputs-30,000 auditory nerve fibers or 10(6) optic nerve fibers-a manageably small number of perceptually relevant features. Here we describe an approach to solving dimensionality reduction problems that uses easily measured local metric information to learn the underlying global geometry of a data set. Unlike classical techniques such as principal component analysis (PCA) and multidimensional scaling (MDS), our approach is capable of discovering the nonlinear degrees of freedom that underlie complex natural observations, such as human handwriting or images of a face under different viewing conditions. In contrast to previous algorithms for nonlinear dimensionality reduction, ours efficiently computes a globally optimal solution, and, for an important class of data manifolds, is guaranteed to converge asymptotically to the true structure.  相似文献   

Research in latin america     

da Silva CG 《Science (New York, N.Y.)》1995,268(5207):14-15

  相似文献   

Hill to hill variations in tuber yield of potatoes in Alberta     

George H. Silva  William T. Andrew 《American Journal of Potato Research》1985,62(3):119-127

The hill to hill variation in tuber yield and mainstem number was studied on 18 potato farms. There were up to 14-fold differences in the tuber yield per hill among plants of Norland, Russet Burbank, Norchip, Carlton and Alaska Red. The mainstem number was more variable than tuber weight per hill in Norland, Russet Burbank and Alaska Red. However, the opposite was true in Norchip and Carlton. In nearly all comparisons, the number of tubers per hill was less variable than tuber weight and mainstem number per hill. The total variation in tuber weight found in about 50% of the samples could be explained by the variance of hills within rows. Even in samples where an added variance component due to differences among rows was present, relatively more variation occurred within than among rows. The correlation coefficients between the number of mainstems and tuber weight per hill were positive but significant (P&< 0.05) only in Norland and Norchip. The correlation coefficients between the number of mainstems and number of tubers per hill were also positive but slightly higher and significant (P<0.01) in all 5 cultivars. The coefficient of determination values indicated that variation in cut seed piece weight explained only about 10% of the total variation in tuber weight harvested per hill. At a spacing of 30 cm within the row, a major proportion of hill to hill variation in tuber yield had to be explained by factors other than the seed piece weight.  相似文献   

Bactericidal activity of zinc oxide particles embedded in poly(vinyl pyrrolidone) electrospun fibers     

Fernando A. G. da Silva Jr.  Rafael C. Libório  Mateus M. da Costa  Helinando P. de Oliveira 《Fibers and Polymers》2014,15(9):1793-1796

Composites of metal oxide nanoparticles incorporated into poly(vinyl pyrrolidone) electrospun fibers can be considered potential and low cost bactericidal agents. Homogeneous distribution of nanoparticles in the core of fibers and minimal aggregation induced by strong interaction with polymeric template are factors that contribute with diffusion of metal oxide nanoparticles from bulk to the fiber surface and subsequent release of nanoparticles to bacterial culture. Hybrid electrospun fibers were successfully applied against bacteria as a result of reasonable degree of interaction between zinc oxide and fibers as detected from FTIR analysis, DSC curves and SEM images.  相似文献   

Quince (Cydonia oblonga miller) fruit characterization using principal component analysis     

Silva BM  Andrade PB  Martins RC  Valentão P  Ferreres F  Seabra RM  Ferreira MA 《Journal of agricultural and food chemistry》2005,53(1):111-122

This paper presents a large amount of data on the composition of quince fruit with regard to phenolic compounds, organic acids, and free amino acids. Subsequently, principal component analysis (PCA) is carried out to characterize this fruit. The main purposes of this study were (i) the clarification of the interactions among three factors-quince fruit part, geographical origin of the fruits, and harvesting year-and the phenolic, organic acid, and free amino acid profiles; (ii) the classification of the possible differences; and (iii) the possible correlation among the contents of phenolics, organic acids, and free amino acids in quince fruit. With these aims, quince pulp and peel from nine geographical origins of Portugal, harvested in three consecutive years, for a total of 48 samples, were studied. PCA was performed to assess the relationship among the different components of quince fruit phenolics, organic acids, and free amino acids. Phenolics determination was the most interesting. The difference between pulp and peel phenolic profiles was more apparent during PCA. Two PCs accounted for 81.29% of the total variability, PC1 (74.14%) and PC2 (7.15%). PC1 described the difference between the contents of caffeoylquinic acids (3-O-, 4-O-, and 5-O-caffeoylquinic acids and 3,5-O-dicaffeoylquinic acid) and flavonoids (quercetin 3-galactoside, rutin, kaempferol glycoside, kaempferol 3-glucoside, kaempferol 3-rutinoside, quercetin glycosides acylated with p-coumaric acid, and kaempferol glycosides acylated with p-coumaric acid). PC2 related the content of 4-O-caffeoylquinic acid with the contents of 5-O-caffeoylquinic and 3,5-O-dicaffeoylquinic acids. PCA of phenolic compounds enables a clear distinction between the two parts of the fruit. The data presented herein may serve as a database for the detection of adulteration in quince derivatives.  相似文献   

Comparison of volatile acid number test with enzymatic acetic acid assay for assessment of seafood quality     

H T McCarthy  P C Ellis  M L Silva  B Mills 《Journal of the Association of Official Analytical Chemists》1989,72(5):828-834

Volatile acid number, an official AOAC method for assessing seafood quality, was compared with an enzymatic method for measuring acetic acid. Thirty-eight samples of fresh fish and 23 samples of canned fish were evaluated. The data showed high positive correlations between volatile acid number and enzymatic acetic acid methods; the correlation coefficient was 0.98 for fresh fish and 0.95 for canned fish. Positive correlation coefficients of 0.93 and 0.96 were also associated with samples of fish divided into 2 groups on the basis of acceptable or unacceptable quality, respectively. There was no significant difference between the means for the volatile acid number and enzymatic acetic acid procedures at the 5% level of significance. Decomposition studies on cod and mackerel, representing a lean and fatty fish, respectively, were monitored over 9 days by using the following analyses: volatile acid number, acetic acid, total volatile bases, and thiobarbituric acid. Results of the decomposition studies showed that enzymatic acetic acid levels closely paralleled volatile acid number values in both lean and fatty fish. Total volatile bases was a reliable supplemental measure for evaluating lean seafood quality, whereas thiobarbituric acid was more appropriate for further assessment of fatty fish quality.  相似文献   

Factor analysis applied in genomic selection studies in the breeding of Coffea canephora     

Paixão  Pedro Thiago Medeiros  Nascimento  Ana Carolina Campana  Nascimento  Moysés  Azevedo  Camila Ferreira  Oliveira  Gabriela França  da Silva  Felipe Lopes  Caixeta  Eveline Teixeira 《Euphytica》2022,218(4):1-9

Euphytica - Head splitting is a major physiological disease in cabbage. The most effective approach for controlling head splitting is to deploy genetic resistance by breeding cabbage cultivars with...  相似文献   

Orchid bees respond to landscape composition differently depending on the multiscale approach     

da Silva Carneiro  Lázaro  Ribeiro  Milton Cezar  Aguiar  Willian Moura de  de Fátima Priante  Camila  Frantine-Silva  Wilson  Gaglianone  Maria Cristina 《Landscape Ecology》2022,37(6):1587-1601

Landscape Ecology - Multiscale approaches are essential for understanding ecological processes and detecting the scale of effect. However, nested multiscale approaches retain the effect of the...  相似文献   

Impact of fungicide application volume on ASIAN rust control and soybean crop yield     

de Souza  Diego Miranda  Raetano  Carlos Gilberto  Negrisoli  Matheus Mereb  Bernardes  Laryssa Moreira  Junior  Luciano Del Bem  Rodrigues  Danilo Morilha  da Silva  Flávio Nunes  Dario  Gustavo 《European journal of plant pathology / European Foundation for Plant Pathology》2022,163(4):853-864

European Journal of Plant Pathology - Multisite fungicides are an anti-resistance strategy to control Phakopsora pachyrhizi. Among the protective fungicides, mancozeb is a fungicide that has been...  相似文献   

Grapevine anthracnose in berries causes biochemical and enzymatic alterations     

Modesto  Lenon Romano  de Almeida  Anna Flávia Neri  Steiner  Daniel Ricardo Maass  Ribeiro  César Freitas  Nodari  Rubens Onofre  Welter  Leocir José  da Silva  Aparecido Lima 《European journal of plant pathology / European Foundation for Plant Pathology》2022,163(3):695-706

European Journal of Plant Pathology - Anthracnose (Elsinöe ampelina) is a major fungal disease in humid regions, causing damage to grapevine berries and decreasing fruit quality. Studies...  相似文献