4 research outputs found
The I-Imas Project: End-Users Driven Specifications for the Design of a Novel Digital Medical Imaging System
No full textThe sloan digital sky survey reverberation mapping project : ensemble spectroscopic variability of quasar broad emission lines
No full textM.Y.S. acknowledges support from the China Scholarship Council (No. [2013]3009). J.R.T. and Y.S. acknowledge support from NASA through Hubble Fellowship grants #51330 and #51314, respectively, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA under contract NAS 5-26555. W.N.B. acknowledges support from NSF grant AST-1108604 and the V. M. Willaman Endowment. KDD is supported by an NSF AAPF fellowship awarded under NSF grant AST-1302093.We explore the variability of quasars in the Mg ii and Hβ broad emission lines and ultraviolet/optical continuum emission using the Sloan Digital Sky Survey Reverberation Mapping project (SDSS-RM). This is the largest spectroscopic study of quasar variability to date: our study includes 29 spectroscopic epochs from SDSS-RM over 6 months, containing 357 quasars with Mg ii and 41 quasars with Hβ . On longer timescales, the study is also supplemented with two-epoch data from SDSS-I/II. The SDSS-I/II data include an additional 2854 quasars with Mg ii and 572 quasars with Hβ . The Mg ii emission line is significantly variable (Δƒ/ƒ ~ 10% on ~100-day timescales), a necessary prerequisite for its use for reverberation mapping studies. The data also confirm that continuum variability increases with timescale and decreases with luminosity, and the continuum light curves are consistent with a damped random-walk model on rest-frame timescales of ≳5 days. We compare the emission-line and continuum variability to investigate the structure of the broad-line region. Broad-line variability shows a shallower increase with timescale compared to the continuum emission, demonstrating that the broad-line transfer function is not a δ-function. Hβ is more variable than Mg ii (roughly by a factor of ~1.5), suggesting different excitation mechanisms, optical depths and/or geometrical configuration for each emission line. The ensemble spectroscopic variability measurements enabled by the SDSS-RM project have important consequences for future studies of reverberation mapping and black hole mass estimation of 1<픃<2 quasars.Peer reviewe
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Large-Scale Genome-Wide Association Studies and Meta-Analyses of Longitudinal Change in Adult Lung Function
No full textBackground: Genome-wide association studies (GWAS) have identified numerous loci influencing cross-sectional lung function, but less is known about genes influencing longitudinal change in lung function. Methods: We performed GWAS of the rate of change in forced expiratory volume in the first second (FEV1) in 14 longitudinal, population-based cohort studies comprising 27,249 adults of European ancestry using linear mixed effects model and combined cohort-specific results using fixed effect meta-analysis to identify novel genetic loci associated with longitudinal change in lung function. Gene expression analyses were subsequently performed for identified genetic loci. As a secondary aim, we estimated the mean rate of decline in FEV1 by smoking pattern, irrespective of genotypes, across these 14 studies using meta-analysis. Results: The overall meta-analysis produced suggestive evidence for association at the novel IL16/STARD5/TMC3 locus on chromosome 15 (P = 5.71 × 10-7). In addition, meta-analysis using the five cohorts with ≥3 FEV1 measurements per participant identified the novel ME3 locus on chromosome 11 (P = 2.18 × 10-8) at genome-wide significance. Neither locus was associated with FEV1 decline in two additional cohort studies. We confirmed gene expression of IL16, STARD5, and ME3 in multiple lung tissues. Publicly available microarray data confirmed differential expression of all three genes in lung samples from COPD patients compared with controls. Irrespective of genotypes, the combined estimate for FEV1 decline was 26.9, 29.2 and 35.7 mL/year in never, former, and persistent smokers, respectively. Conclusions: In this large-scale GWAS, we identified two novel genetic loci in association with the rate of change in FEV1 that harbor candidate genes with biologically plausible functional links to lung function.Version of Recor
Tratamento de imprecisão em sistemas especialistas
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Produção, Florianópolis, 1991.Esta dissertação apresenta um levantamento do estado da arte no Tratamento de Imprecisão em Sistemas Especialistas. Aborda-se o Raciocínio Humano na Resolução de Problemas e as principais técnicas existentes em tratamento de imprecisão em Inteligência Artificial: Método Bayesiano, Fatores de Certeza, Teoria da Evidência de Dempster e Shafer e Teoria dos Conjuntos Difusos. Para cada uma das técnicas estudadas são apresentados seus fundamentos teóricos, exemplos práticos e uma discussão sobre a performance entre as técnicas em relação aos principais requerimentos a uma técnica ideal no tratamento de imprecisão em Sistemas Especialistas
