972 resultados para recent advances


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Choroideremia is a complex and rare disease that is frequently misdiagnosed due to its similar appearance to classic retinitis pigmentosa. Recent advances in genetic testing have identified specific genetic mutations in many retinal dystrophies, and the identification of the mutation of the CHM gene on the X chromosome 25 years ago has paved the way for gene replacement therapy with the first human trials now underway. This article reviews the epidemiological and pathological features of choroideremia and new prospects in imaging to monitor disease progression, as well as potential treatment approaches for choroideremia.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Monte Carlo integration is firmly established as the basis for most practical realistic image synthesis algorithms because of its flexibility and generality. However, the visual quality of rendered images often suffers from estimator variance, which appears as visually distracting noise. Adaptive sampling and reconstruction algorithms reduce variance by controlling the sampling density and aggregating samples in a reconstruction step, possibly over large image regions. In this paper we survey recent advances in this area. We distinguish between “a priori” methods that analyze the light transport equations and derive sampling rates and reconstruction filters from this analysis, and “a posteriori” methods that apply statistical techniques to sets of samples to drive the adaptive sampling and reconstruction process. They typically estimate the errors of several reconstruction filters, and select the best filter locally to minimize error. We discuss advantages and disadvantages of recent state-of-the-art techniques, and provide visual and quantitative comparisons. Some of these techniques are proving useful in real-world applications, and we aim to provide an overview for practitioners and researchers to assess these approaches. In addition, we discuss directions for potential further improvements.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

With the ongoing shift in the computer graphics industry toward Monte Carlo rendering, there is a need for effective, practical noise-reduction techniques that are applicable to a wide range of rendering effects and easily integrated into existing production pipelines. This course surveys recent advances in image-space adaptive sampling and reconstruction algorithms for noise reduction, which have proven very effective at reducing the computational cost of Monte Carlo techniques in practice. These approaches leverage advanced image-filtering techniques with statistical methods for error estimation. They are attractive because they can be integrated easily into conventional Monte Carlo rendering frameworks, they are applicable to most rendering effects, and their computational overhead is modest.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Estudios dendroecológicos para el análisis de regímentes torrenciales y avenidas

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The cleavage of RNA can be accelerated by a number of factors. These factors include an acidic group (Lewis acid) or a basic group that aids in the deprotonation of the attacking nucleophile, in effect enhancing the nucleophilicity of the nucleophile; an acidic group that can neutralize and stabilize the leaving group; and any environment that can stabilize the pentavalent species that is either a transition state or a short-lived intermediate. The catalytic properties of ribozymes are due to factors that are derived from the complicated and specific structure of the ribozyme–substrate complex. It was postulated initially that nature had adopted a rather narrowly defined mechanism for the cleavage of RNA. However, recent findings have clearly demonstrated the diversity of the mechanisms of ribozyme-catalyzed reactions. Such mechanisms include the metal-independent cleavage that occurs in reactions catalyzed by hairpin ribozymes and the general double-metal-ion mechanism of catalysis in reactions catalyzed by the Tetrahymena group I ribozyme. Furthermore, the architecture of the complex between the substrate and the hepatitis delta virus ribozyme allows perturbation of the pKa of ring nitrogens of cytosine and adenine. The resultant perturbed ring nitrogens appear to be directly involved in acid/base catalysis. Moreover, while high concentrations of monovalent metal ions or polyamines can facilitate cleavage by hammerhead ribozymes, divalent metal ions are the most effective acid/base catalysts under physiological conditions.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This paper reviews the present state of the catalytic enantioselective Reformatsky reaction. Advancements in asymmetric versions of this reaction have recently led to a considerable extension of its scope and applicability, principally due to the use of highly active chiral ligands and very specific reaction conditions.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Co-sponsored in cooperation with the Dept. of Fisheries and Wildlife, Oregon State University.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Includes bibliography.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

v.1. The house, its plan, decoration and care / by Isabel Bevier. -- v.2. Household bacteriology / by S. Maria Elliott. -- v.3. Household hygiene / by S. Maria Elliott. -- v.4. Chemistry of the household / by Margaret E. Dodd. -- v.5. Principles of cookery / by Anna Barrows. -- v.6. Food and dietetics / by Alice P. Norton. -- v.7. Household management by Bertha M. Terrill. -- v.8. Personal hygiene / ed. by M. Le Bosquet. -- v.9. Home care of the sick / by Amy E. Pope. -- v.10. Textiles and clothing / by Kate H. Watson. -- v.11. Study of child life / by Marion F. Washburne. -- v.12. Care of children / by A.C. Cotton.