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排序方式: 共有169条查询结果,搜索用时 21 毫秒
71.
Manuel Escabias Ana M. Aguilera M. Carmen Aguilera-Morillo 《Journal of Classification》2014,31(3):296-324
In many statistical applications data are curves measured as functions of a continuous parameter as time. Despite of their functional nature and due to discrete-time observation, these type of data are usually analyzed with multivariate statistical methods that do not take into account the high correlation between observations of a single curve at nearby time points. Functional data analysis methodologies have been developed to solve these type of problems. In order to predict the class membership (multi-category response variable) associated to an observed curve (functional data), a functional generalized logit model is proposed. Base-line category logit formulations will be considered and their estimation based on basis expansions of the sample curves of the functional predictor and parameters. Functional principal component analysis will be used to get an accurate estimation of the functional parameters and to classify sample curves in the categories of the response variable. The good performance of the proposed methodology will be studied by developing an experimental study with simulated and real data. 相似文献
72.
73.
Finlayson C Pacheco FG Rodríguez-Vidal J Fa DA Gutierrez López JM Santiago Pérez A Finlayson G Allue E Baena Preysler J Cáceres I Carrión JS Fernández Jalvo Y Gleed-Owen CP Jimenez Espejo FJ López P López Sáez JA Riquelme Cantal JA Sánchez Marco A Guzman FG Brown K Fuentes N Valarino CA Villalpando A Stringer CB Martinez Ruiz F Sakamoto T 《Nature》2006,443(7113):850-853
The late survival of archaic hominin populations and their long contemporaneity with modern humans is now clear for southeast Asia. In Europe the extinction of the Neanderthals, firmly associated with Mousterian technology, has received much attention, and evidence of their survival after 35 kyr bp has recently been put in doubt. Here we present data, based on a high-resolution record of human occupation from Gorham's Cave, Gibraltar, that establish the survival of a population of Neanderthals to 28 kyr bp. These Neanderthals survived in the southernmost point of Europe, within a particular physiographic context, and are the last currently recorded anywhere. Our results show that the Neanderthals survived in isolated refuges well after the arrival of modern humans in Europe. 相似文献
74.
Fabiane Carvalho Ballotin Mayra Nascimento Sara Silveira Vieira Alexandre Carvalho Bertoli Ottávio Carmignano Ana Paula de Carvalho Teixeira Rochel Montero Lago 《矿物冶金与材料学报》2020,27(1):46-54
In this work, different magnesium silicate mineral samples based on antigorite, lizardite, chrysotile (which have the same general formula Mg3Si2O5(OH)4), and talc (Mg3Si4O10(OH)2) were reacted with KOH to prepare catalysts for biodiesel production. Simple impregnation with 20wt% K and treatment at 700–900°C led to a solid-state reaction to mainly form the K2MgSiO4 phase in all samples. These results indicate that the K ion can diffuse into the different Mg silicate structures and textures, likely through intercalation in the interlayer space of the different mineral samples followed by dehydroxylation and K2MgSiO4 formation. All the materials showed catalytic activity for the transesterification of soybean oil (1:6 of oil : methanol molar ratio, 5wt% of catalyst, 60°C). However, the best results were obtained for the antigorite and chrysotile precursors, which are discussed in terms of mineral structure and the more efficient formation of the active phase K2MgSiO4. 相似文献
75.
A Ramirez H Vial J Barailler H Pacheco 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1978,187(1):53-56
These drugs, except centrophenoxine, inhibit in vitro in a competitive manner, norepinephrin uptake in Rat hypothalamus and cortex, and dopamine uptake in corpus striatum and cortex, at higher concentrations than d.l. amphetamine; this alone inhibits serotonin uptake in hypothalamus. 相似文献
76.
We have discovered an expansive photoreceptive 'net' in the mouse inner retina, visualized by using an antiserum against melanopsin, a likely photopigment. This immunoreactivity is evident in a subset of retinal ganglion cells that morphologically resemble those that project to the suprachiasmatic nucleus (SCN), the site of the primary circadian pacemaker. Our results indicate that this bilayered photoreceptive net is anatomically distinct from the rod and cone photoreceptors of the outer retina, and suggest that it may mediate non-visual photoreceptive tasks such as the regulation of circadian rhythms. 相似文献
77.
Disruption of CREB function in brain leads to neurodegeneration 总被引:24,自引:0,他引:24
Mantamadiotis T Lemberger T Bleckmann SC Kern H Kretz O Martin Villalba A Tronche F Kellendonk C Gau D Kapfhammer J Otto C Schmid W Schütz G 《Nature genetics》2002,31(1):47-54
Control of cellular survival and proliferation is dependent on extracellular signals and is a prerequisite for ordered tissue development and maintenance. Activation of the cAMP responsive element binding protein (CREB) by phosphorylation has been implicated in the survival of mammalian cells. To define its roles in the mouse central nervous system, we disrupted Creb1 in brain of developing and adult mice using the Cre/loxP system. Mice with a Crem(-/-) background and lacking Creb in the central nervous system during development show extensive apoptosis of postmitotic neurons. By contrast, mice in which both Creb1 and Crem are disrupted in the postnatal forebrain show progressive neurodegeneration in the hippocampus and in the dorsolateral striatum. The striatal phenotype is reminiscent of Huntington disease and is consistent with the postulated role of CREB-mediated signaling in polyglutamine-triggered diseases. 相似文献
78.
Strässer K Masuda S Mason P Pfannstiel J Oppizzi M Rodriguez-Navarro S Rondón AG Aguilera A Struhl K Reed R Hurt E 《Nature》2002,417(6886):304-308
79.
Verjovski-Almeida S DeMarco R Martins EA Guimarães PE Ojopi EP Paquola AC Piazza JP Nishiyama MY Kitajima JP Adamson RE Ashton PD Bonaldo MF Coulson PS Dillon GP Farias LP Gregorio SP Ho PL Leite RA Malaquias LC Marques RC Miyasato PA Nascimento AL Ohlweiler FP Reis EM Ribeiro MA Sá RG Stukart GC Soares MB Gargioni C Kawano T Rodrigues V Madeira AM Wilson RA Menck CF Setubal JC Leite LC Dias-Neto E 《Nature genetics》2003,35(2):148-157
Schistosoma mansoni is the primary causative agent of schistosomiasis, which affects 200 million individuals in 74 countries. We generated 163,000 expressed-sequence tags (ESTs) from normalized cDNA libraries from six selected developmental stages of the parasite, resulting in 31,000 assembled sequences and 92% sampling of an estimated 14,000 gene complement. By analyzing automated Gene Ontology assignments, we provide a detailed view of important S. mansoni biological systems, including characterization of metazoa-specific and eukarya-conserved genes. Phylogenetic analysis suggests an early divergence from other metazoa. The data set provides insights into the molecular mechanisms of tissue organization, development, signaling, sexual dimorphism, host interactions and immune evasion and identifies novel proteins to be investigated as vaccine candidates and potential drug targets. 相似文献
80.
Pacheco YM Abia R Olivera A Spiegel S Ruiz-Gutierrez V Muriana FJ 《Cellular and molecular life sciences : CMLS》2003,60(12):2757-2766
Proof for the role of triacylglycerol-rich lipoproteins (TRLs) in the development of cardiovascular events is accumulating. We recently reported that postprandial TRLs bind to and internalize into human aortic vascular smooth muscle cells (HA-VSMCs) by a lipid-dependent mechanism. We now show that postprandial TRLs triggered hydrolysis of sphingomyelin and stimulation of the sphingosine kinase producing sphingosine 1-phosphate (S1P). In addition, postprandial TRLs exhibited survival and mitogenic effects. Interestingly, the signals were modulated by the nature of the fatty acids located at the sn-2 position in the triacylglycerol molecules of TRL. This lipid-stereospecific regulation of S1P cellular levels in HA-VSMCs provides a novel insight into the intrinsic role of dietary fatty acids and the mechanism mediated by triacylglycerol-containing postprandial lipoproteins in the pathogenesis of atherosclerosis.Received 14 August 2003; received after revision 8 October 2003; accepted 15 October 2003 相似文献