990 resultados para Differentiation Strategies


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Methods for generating a new population are a fundamental component of estimation of distribution algorithms (EDAs). They serve to transfer the information contained in the probabilistic model to the new generated population. In EDAs based on Markov networks, methods for generating new populations usually discard information contained in the model to gain in efficiency. Other methods like Gibbs sampling use information about all interactions in the model but are computationally very costly. In this paper we propose new methods for generating new solutions in EDAs based on Markov networks. We introduce approaches based on inference methods for computing the most probable configurations and model-based template recombination. We show that the application of different variants of inference methods can increase the EDAs’ convergence rate and reduce the number of function evaluations needed to find the optimum of binary and non-binary discrete functions.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

New methods of surface modification of transparent silicone substrate were developed, and a new set of cell culture devices that provide homogeneous substrate strain was designed. Using the new device, effects of cyclic substrate strain on bone marrow mesenchymal stem cells(MSCs) were studied. It was found that cyclic strain influenced proliferation and differentiation of bone marrow MSCs in different ways.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This study provides guidance on statewide organization for the commercial hard clam culture industry in Florida. The study characterizes the structure of and identifies strategies for successful agricultural and aquacultural organizations designed to provide the resources needed to solve current and projected industry problems. Objectives were to 1) characterize the structure of successful and relevant organizations, 2) identify successful revenue generating strategies, 3) provide the hard clam culture industry with options to help facilitate their organizational decisions, and 4) assist clam growers in Florida in developing an umbrella organizational strategy that will meet their future industry needs. (PDF has 60 pages.)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This research is part of the Socioeconomic Research & Monitoring Program for the Florida Keys National Marine Sanctuary (FKNMS), which was initiated in 1998. In 1995-96, a baseline study on the knowledge, attitudes and perceptions of proposed FKNMS management strategies and regulations of commercial fishers, dive operators and on selected environmental group members was conducted by researchers at the University of Florida and the University of Miami’s Rosenstiel School of Atmospheric and Marine Science (RSMAS). The baseline study was funded by the U.S. Man and the Biosphere Program, and components of the study were published by Florida Sea Grant and in several peer reviewed journals. The study was accepted into the Socioeconomic Research & Monitoring Program at a workshop to design the program in 1998, and workshop participants recommended that the study be replicated every ten years. The 10-year replication was conducted in 2004-05 (commercial fishers) 2006 (dive operators) and 2007 (environmental group members) by the same researchers at RSMAS, while the University of Florida researchers were replaced by Thomas J. Murray & Associates, Inc., which conducted the commercial fishing panels in the FKNMS. The 10-year replication study was funded by NOAA’s Coral Reef Conservation Program. The study not only makes 10-year comparisons in the knowledge, attitudes and perceptions of FKNMS management strategies and regulations, but it also establishes new baselines for future monitoring efforts. Things change, and following the principles of “adaptive management”, management has responded with changes in the management plan strategies and regulations. Some of the management strategies and regulations that were being proposed at the time of the baseline 1995-96 study were changed before the management plan and regulations went into effect in July 1997. This was especially true for the main focus of the study which was the various types of marine zones in the draft and final zoning action plan. Some of the zones proposed were changed significantly and subsequently new zones have been created. This study includes 10-year comparisons of socioeconomic/demographic profiles of each user group; sources and usefulness of information; knowledge of purposes of FKNMS zones; perceived beneficiaries of the FKNMS zones; views on FKNMS processes to develop management strategies and regulations; views on FKNMS zone outcomes; views on FKNMS performance; and general support for FKNMS. In addition to new baseline information on FKNMS zones, new baseline information was developed for spatial use, investment and costs-and-earnings for commercial fishers and dive operators, and views on resource conditions for all three user groups. Statistical tests were done to detect significant changes in both the distribution of responses to questions and changes in mean scores for items replicated over the 10-year period. (PDF has 143 pages.)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Background: The ability to recreate an optimal cellular microenvironment is critical to understand neuronal behavior and functionality in vitro. An organized neural extracellular matrix (nECM) promotes neural cell adhesion, proliferation and differentiation. Here, we expanded previous observations on the ability of nECM to support in vitro neuronal differentiation, with the following goals: (i) to recreate complex neuronal networks of embryonic rat hippocampal cells, and (ii) to achieve improved levels of dopaminergic differentiation of subventricular zone (SVZ) neural progenitor cells. Methods: Hippocampal cells from E18 rat embryos were seeded on PLL- and nECM-coated substrates. Neurosphere cultures were prepared from the SVZ of P4-P7 rat pups, and differentiation of neurospheres assayed on PLL- and nECM-coated substrates. Results: When seeded on nECM-coated substrates, both hippocampal cells and SVZ progenitor cells showed neural expression patterns that were similar to their poly-L-lysine-seeded counterparts. However, nECM-based cultures of both hippocampal neurons and SVZ progenitor cells could be maintained for longer times as compared to poly-L-lysine-based cultures. As a result, nECM-based cultures gave rise to a more branched neurite arborization of hippocampal neurons. Interestingly, the prolonged differentiation time of SVZ progenitor cells in nECM allowed us to obtain a purer population of dopaminergic neurons. Conclusions: We conclude that nECM-based coating is an efficient substrate to culture neural cells at different stages of differentiation. In addition, neural ECM-coated substrates increased neuronal survival and neuronal differentiation efficiency as compared to cationic polymers such as poly-L-lysine.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

We used multipotent stem cells (MSCs) derived from the young rat subventricular zone (SVZ) to study the effects of glutamate in oligodendrocyte maturation. Glutamate stimulated oligodendrocyte differentiation from SVZ-derived MSCs through the activation of specific N-methyl-D-aspartate (NMDA) receptor subunits. The effect of glutamate and NMDA on oligodendrocyte differentiation was evident in both the number of newly generated oligodendrocytes and their morphology. In addition, the levels of NMDAR1 and NMDAR2A protein increased during differentiation, whereas NMDAR2B and NMDAR3 protein levels decreased, suggesting differential expression of NMDA receptor subunits during maturation. Microfluorimetry showed that the activation of NMDA receptors during oligodendrocyte differentiation elevated cytosolic calcium levels and promoted myelination in cocultures with neurons. Moreover, we observed that stimulation of MSCs by NMDA receptors induced the generation of reactive oxygen species (ROS), which were negatively modulated by the NADPH inhibitor apocynin, and that the levels of ROS correlated with the degree of differentiation. Taken together, these findings suggest that ROS generated by NADPH oxidase by the activation of NMDA receptors promotes the maturation of oligodendrocytes and favors myelination

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Sources of fish and fishery products in Nigeria were reviewed. The problems of various agencies involved in freshwater fish production in Nigeria were also analysed, such problems included shortage of manpower, inadequate training for personnel, shortage of funds, lack of infrastructures, among others

Relevância:

20.00% 20.00%

Publicador:

Resumo:

There is increasing awareness of aquaculture in Nigeria today for a number of reasons namely: water pollution, declining catch and the awareness of the attractiveness of aquaculture as an investment area and a pivotal point for national development. The development of aquaculture in Nigeria, requires the building up of institutions at the grassroot level and the formulation of policies and programmes for the small fishfarmer. This of course would be backed up by a sound technology generation, verification and packaging, dissemination and use programme

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Cost projections for the establishment of a fish farm in Nigeria was conducted. It is shown that fish farming should be a lucrative venture. However, many private fish farms are not making the desired profits because of a variety of problems. Besides managerial incompetence, availability of fingerlings for stocking in the ponds is shown to be a serious handicap to the success of investments in a fish farm. It is suggested that where the funds are available, each farm should be equipped with facilities for raising its needs of fingerlings. Since useful capital would be involved and knowledgeable experts to run the hatcheries are few, it is recommended that fish farms within a state or adjacent states should combine to establish viable cooperative hatcheries