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G Károlyi

Publications and source records attributed to G Károlyi.

At least 19 recordsLinked to original sources
PubMed2006

Coexistence of inertial competitors in chaotic flows.

We investigate the dynamics of inertial particles immersed in open chaotic flows. We consider the generic problem of competition between different species, e.g., phytoplankton populations in oceans. The strong influence from inertial effects is shown to result in the persistence of different species even in cases when the passively advected species cannot coexist. Multispecies coexistence in the ocean can be explained by the fact that the unstable manifold is different for each advected competitor of different size.

Algorithms↗
PubMed2000

Chaotic flow: the physics of species coexistence.

Hydrodynamical phenomena play a keystone role in the population dynamics of passively advected species such as phytoplankton and replicating macromolecules. Recent developments in the field of chaotic advection in hydrodynamical flows encourage us to revisit the population dynamics of species competing for the same resource in an open aquatic system. If this aquatic environment is homogeneous and well-mixed then classical studies predict competitive exclusion of all but the most perfectly adapted species. In fact, this homogeneity is very rare, and the species of the community (at least on an ecological observation time scale) are in nonequilibrium coexistence. We argue that a peculiar small-scale, spatial heterogeneity generated by chaotic advection can lead to coexistence. In open flows this imperfect mixing lets the populations accumulate along fractal filaments, where competition is governed by an "advantage of rarity" principle. The possibility of this generic coexistence sheds light on the enrichment of phytoplankton and the information integration in early macromolecule evolution.

Ecology↗
PubMed1999

[Corneal arcus and life expectancy].

In 1964-66, the authors completed the comprehensive medical screening of 1412 persons. Apart from the indicators of health state they also recorded their social and cultural parameters. The diagnoses they registered included AC, which has been covered in literature in rather contradicting ways. They found no data concerning survival; as analysing such a correlation is only possible within the frame-work of a several-decade follow-up study. By the end of the follow-up stage (31:12:1994), after 30 years, 1375 persons had died. Their death certificates and--if there were any--necropsy records have been processed and thoroughly analysed. They examined the occurrence of AC, life duration and survival probability--all in correlation with age, gender, constitution, certain diseases (hypertonia, ostheoarthrosis) and diagnoses at death (ischaemic heart diseases, acute myocardiac infarction, cerebrovascular diseases). They point it out that the occurrence of AC is significantly higher among males, but it increases in strong correlation with age in both sexes. Those who had AC were found to be older at the time of death, but it doesn't mean that AC correlates with better life expectancy--it means that AC occurs at older age. The survival probability of men over 75 was better than that of women. On the whole, AC is unfavourable concerning life expectancy, but the later it occurs, the less it can be used as an indicator of life expectancy. It was found that greater average weight correlated with longer average life duration, while among females the more a person weighed, the less frequent AC became. It was true for each weight group that those with AC had worse life expectancy. Altogether those with no AC were found to suffer from hypertonia significantly more frequently. The life expectancy of those with both AC and hypertonia, however, was always worse than those with hypertonia only, regardless of age and the type of hypertonia. Generally women are in a more favourable position, but in the 'serious' and 'very serious' hypertonia groups there is practically no difference in the survival of the two sexes. The authors have also found that AC has a significant negative prognostical value concerning survival and correlation with ostheoarthrosis, ischaemic heart diseases and cerebrovascular diseases. The correlation of AC with acute myocardiac infarction could not be proved convincingly.

Aged↗
PubMed1999

Chemical or biological activity in open chaotic flows.

We investigate the evolution of particle ensembles in open chaotic hydrodynamical flows. Active processes of the type A+B-->2B and A+B-->2C are considered in the limit of weak diffusion. As an illustrative advection dynamics we consider a model of the von Kármán vortex street, a time-periodic two-dimensional flow of a viscous fluid around a cylinder. We show that a fractal unstable manifold acts as a catalyst for the process, and the products cover fattened-up copies of this manifold. This may account for the observed filamental intensification of activity in environmental flows. The reaction equations valid in the wake are derived either in the form of dissipative maps or differential equations depending on the regime under consideration. They contain terms that are not present in the traditional reaction equations of the same active process: the decay of the products is slower while the productivity is much faster than in homogeneous flows. Both effects appear as a consequence of underlying fractal structures. In the long time limit, the system locks itself in a dynamic equilibrium state synchronized to the flow for both types of reactions. For particles of finite size an emptying transition might also occur leading to no products left in the wake.

Journal Article↗
PubMed1993

[Longitudinal socio-gerontologic geronto-epidemiologic study in Hajdúszoboszló (SZOLOVI, 1964-1991)].

The tendencies of the demographic changes in Hungary, the trend and pace of the expected development of the age distribution and social stratification anticipated even in the early sixties that the problem of the ageing population (of the agriculture) would raise to national level and a considerable part of its consequent tasks will be the share of the national health care. So began in 1964 in Hajdúszoboszló a social gerontological-geroepidemiological study of those who were 60 and over and had agricultural profession. This study was developed into a longitudinal one (in the years 1986, 1990, 1991 and 1993), and is being continued even today.

Aged↗
PubMed1991

Value of mortality data and necropsy records in monitoring morbidity in a population.

STUDY OBJECTIVE: The aim was to compare the value of four sources of data in assessing morbidity in a population: (1) data from a screening programme including follow up records, (2) death certifications by attending physicians, (3) death certifications by doctor-coroners, and (4) necropsy reports. DESIGN: The study was a cohort analysis of health and mortality in a sample of agricultural workers first examined in 1964-66 when they were aged 60 years or older. Follow up examinations enabled morbidity assessment to be made and ICD diagnostic categories to be compared with data available on persons in the cohort who had died. SETTING: Hajdúszoboszló, a small town in eastern Hungary. PARTICIPANTS: 1412 persons (96.1% of those aged greater than or equal to 60 years) were examined in 1964-6. Those still alive and available in 1989 were examined again. Necropsy records were available for 144 persons from the cohort in 1989 and were extensively reviewed in comparison with data available from other sources. MEASUREMENTS AND MAIN RESULTS: Comparison of causes of death established at necropsy showed marked differences from those registered by attending physicians and doctor-coroners, deviations ranging from -91.6% to +74.8%; 19.4% of underlying causes of death occurred exclusively in the necropsy group. Major divergencies in diagnostic classification occurred in the three data sources, particularly for diseases of the circulatory system, where hypertensive renal disease, old myocardial infarction, acute cerebrovascular disease, and venous thrombosis were rarely documented by physicians/coroners. When necropsy data were used the number of diagnostic categories increased strikingly over the other sources of information. Necropsy records revealed quantitatively similar information on morbidity to follow up examination though there were qualitative differences, necropsy being less likely to document diagnoses of endocrine disorders, mental and neurological diseases, digestive disorders, and musculosketal disorders. CONCLUSIONS: Necropsy records contain much valuable material not available from other sources, exceeding by ninefold the amount of information reported at present. A way should be found to make use of this large data pool.

Aged↗
PubMed1986

Prevalence of minor congenital anomalies in diabetic children.

The prevalence of 52 minor congenital anomalies (MCAs) was determined in 111 children with insulin dependent diabetes mellitus (IDDM), and in 111 healthy matched control subjects. The average MCA per person was 1.60 in diabetic children and 0.86 in the controls (p less than 0.001). The difference was exclusively due to the significantly higher proportion of subjects with 3 or more MCAs in the diabetic group (27.0 versus 9.9%; p less than 0.001). No specific MCA characteristic of IDDM was found.

Adolescent↗