Biomedical subjects

M L De Castro

Publications and source records attributed to M L De Castro.

3 recordsLinked to original sources

PubMed2001

Stability in a metapopulation model with density-dependent dispersal.

A spatially explicit metapopulation model with positive density-dependent migration is analysed. We obtained conditions under which a previously stable system can be driven to instability caused by a density-dependent migration mechanism. The stability boundary depends on the rate of increase of the number of migrants on each site at local equilibrium, on the intrinsic rate of increase at local level, on the number of patches, and on topological aspects regarding the connectivity between patches. A concrete example is presented illustrating the dynamics on the dispersal-induced unstable regime.

Animals↗

PubMed2000

Synchronism in a metapopulation model.

We consider a spatially explicit meta-population model with interaction among the two nearest neighbors to relate, with a simple mathematical expression, chaos in the local, uncoupled, populations, the degree of interaction among patches, size of the meta-population, and the stability of the synchronized attractor. Since synchronism is strongly correlated with extinction, our results can provide useful information on factors leading to population extinction.

Animals↗

PubMed1998

A prospective trial of self-expanding metal coated stents in the palliation of malignant dysphagia.

OBJECTIVE: To analyze the use of self-expanding metal coated esophageal stents a palliative therapy of malignant dysphagia. METHOD: We performed a one year prospective study placing 12 stents in 10 patients with malignant dysphagia. RESULTS: The insertion mean time was lower than 25 min, and most of our patients (70%) reported a good tolerance. Dysphagia score improved immediately and it lasted until death with no occlusions. Complications appeared early, 17% at the time of placement, with one patient having a life-threatening complication. The probability for these patients not to develop any complications after the three first weeks will be about 60%. CONCLUSIONS: Self-expanding metal coated esophageal stents provide a fast and lasting relief in malignant dysphagia, with a good tolerance.

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