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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.
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
74.
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
75.
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
76.
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
77.
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
78.
RGM is a repulsive guidance molecule for retinal axons 总被引:15,自引:0,他引:15
Monnier PP Sierra A Macchi P Deitinghoff L Andersen JS Mann M Flad M Hornberger MR Stahl B Bonhoeffer F Mueller BK 《Nature》2002,419(6905):392-395
Axons rely on guidance cues to reach remote targets during nervous system development. A well-studied model system for axon guidance is the retinotectal projection. The retina can be divided into halves; the nasal half, next to the nose, and the temporal half. A subset of retinal axons, those from the temporal half, is guided by repulsive cues expressed in a graded fashion in the optic tectum, part of the midbrain. Here we report the cloning and functional characterization of a membrane-associated glycoprotein, which we call RGM (repulsive guidance molecule). This molecule shares no sequence homology with known guidance cues, and its messenger RNA is distributed in a gradient with increasing concentration from the anterior to posterior pole of the embryonic tectum. Recombinant RGM at low nanomolar concentration induces collapse of temporal but not of nasal growth cones and guides temporal retinal axons in vitro, demonstrating its repulsive and axon-specific guiding activity. 相似文献
79.
Jinks RN Markley TL Taylor EE Perovich G Dittel AI Epifanio CE Cronin TW 《Nature》2002,420(6911):68-70
Hydrothermal vents along the mid-ocean ridges host ephemeral ecosystems of diverse endemic fauna including several crustacean species, some of which undergo planktonic development as larvae up to 1,000 m above and 100 km away from the vents. Little is known about the role of vision in the life history of vent fauna. Here we report that planktonic zoea larvae of the vent crab Bythograea thermydron possess image-forming compound eyes with a visual pigment sensitive to the blue light of mesopelagic waters. As they metamorphose and begin to descend to and settle at the vents, they lose their image-forming optics and develop high-sensitivity naked-retina eyes. The spectral absorbance of the visual pigment in these eyes shifts towards longer wavelengths from larva to postlarva to adult. This progressive visual metamorphosis trades imaging for increased sensitivity, and changes spectral sensitivity from the blue wavelengths of the larval environment towards the dim, longer wavelengths produced in the deeper bathypelagic vent environment of the adults. As hydrothermal vents produce light, vision may supplement thermal and chemical senses to orient postlarval settlement at vent sites. 相似文献
80.