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Biomedical subjects

H Giacomini

Publications and source records attributed to H Giacomini.

10 recordsLinked to original sources
PubMed2000

Shape of attractors for three-dimensional dissipative dynamical systems

We introduce a method to bound attractors of dissipative dynamical systems in phase and parameter spaces. The method is based on the determination of families of transversal surfaces (surfaces crossed by the flow in only one direction). This technique yields very restrictive geometric bounds in phase space for the attractors. It also gives ranges of parameters of the system for which no chaotic behavior is possible. We illustrate our method on different three-dimensional dissipative systems.

Journal Article↗
PubMed1997

A statistical analysis of sequences of cardiac interbeat intervals does not support the chaos hypothesis.

Series of cardiac interbeat intervals were recorded in 34 mice and described using an original technique. The different intervals were divided into six classes according to their lengths. The different successions of pairs of intervals were counted with the help of a software programme devoted to lexical analysis. Most of the mice showed a very similar pattern of repeated sequences of interbeat intervals, statistically different from a random distribution. One-, two- or three-dimensional chaotic discrete maps were used to generate series that were then analyzed in the same way. They failed to give a distribution pattern of repeated sequences similar to the biological ones. On the contrary, series generated using a random component, and limited in amplitude by a feed-back correction occurring when the intervals reached a lower or an upper threshold, gave distributions of values very similar to biological ones. Moreover, the natural diversity observed between mice was easily reproduced by fluctuation of these different parameters. It is suggested that a very simple process, not completely deterministic, could better explain interbeat interval regulation in normal mice than did chaotic phenomena, which need complex biological processes.

Animals↗
PubMed1996

Health conditions in Argentina: facing the twenty-first century.

This paper describes the state of health in Argentina. As in other countries in the Latin American region, the public sector and the role of the state in Argentina are in the midst of structural transformation. Public policy has been formulated with the aim of improving economic efficiency in the long term, often at the cost of basic services, such as health, education and safety. Provision of health care services to a population characterized by high levels of poverty and unemployment, which is also rapidly growing and ageing, needs to be addressed when major policies are decided. Otherwise, a large group of inhabitants in Argentina will not be able to reach the universally proposed minimum levels of health by the year 2000.

Adolescent↗
PubMed1995

Epidemic of cholera among the aborigines of northern Argentina.

In February 1992, an epidemic of cholera began in Argentina. The first known case appeared in an aborigine population living by the Pilcomayo river on the Bolivian border. By the end of that year, 551 cases and 15 deaths were reported to the health authorities. Epidemiological analysis helped identify the pattern of transmission of the disease in this region of South America. Polluted watercourses and little pools, formed after the rainy season, were identified as the single source of infection for subsequent cases. Then, the epidemic adopted a person-to-person pattern of transmission and was propagated over a long course with weekly occurrence. Anthropological, cultural, and other factors that contributed to the origin and spread of cholera in northern Argentina are described in this study.

Adult↗