Global adaptation in networks of selfish components: emergent associative memory at the system scale

In some circumstances complex adaptive systems composed of numerous self-interested agents can self-organise into structures that enhance global adaptation, efficiency or function. However, the general conditions for such an outcome are poorly understood and present a fundamental open question for domains as varied as ecology, sociology, economics, organismic biology and technological infrastructure design. In contrast, sufficient conditions for artificial neural networks to form structures that perform collective computational processes such as associative memory/recall, classification, generalisation and optimisation, are well-understood. Such global functions within a single agent or organism are not wholly surprising since the mechanisms (e.g. Hebbian learning) that create these neural organisations may be selected for this purpose, but agents in a multi-agent system have no obvious reason to adhere to such a structuring protocol or produce such global behaviours when acting from individual self-interest. However, Hebbian learning is actually a very simple and fully-distributed habituation or positive feedback principle. Here we show that when self-interested agents can modify how they are affected by other agents (e.g. when they can influence which other agents they interact with) then, in adapting these inter-agent relationships to maximise their own utility, they will necessarily alter them in a manner homologous with Hebbian learning. Multi-agent systems with adaptable relationships will thereby exhibit the same system-level behaviours as neural networks under Hebbian learning. For example, improved global efficiency in multi-agent systems can be explained by the inherent ability of associative memory to generalise by idealising stored patterns and/or creating new combinations of sub-patterns. Thus distributed multi-agent systems can spontaneously exhibit adaptive global behaviours in the same sense, and by the same mechanism, as the organisational principles familiar in connectionist models of organismic learning

Association between different levels of dysglycemia and metabolic syndrome in pregnancy

<p>Abstract</p> <p>Background</p> <p>In this study, we sought to evaluate the prevalence of metabolic syndrome (MS) in a cohort of pregnant women with a wide range of glucose tolerance, prepregnancy risk factors for MS during pregnancy, and the effects of MS in the outcomes in the mother and in the newborn.</p> <p>Methods</p> <p>One hundred and thirty six women with positive screening for gestational diabetes mellitus (GDM) were classified by two diagnostic methods: glycemic profile and 100 g OGTT as normoglycemic, mild gestational hyperglycemic, GDM, and overt GDM. Markers of MS were measured between 2428^thduring the screening.</p> <p>Results</p> <p>The prevalence of MS was: 0%; 20.0%; 23.5% and 36.4% in normoglycemic, mild hyperglycemic, GDM, and overt GDM groups, respectively. Previous history of GDM with or without insulin use, BMI ≥ 25, hypertension, family history of diabetes in first degree relatives, non-Caucasian ethnicity, history of prematurity and polihydramnios were statistically significant prepregnancy predictors for MS in the index pregnancy, that by its turn increased the adverse outcomes in the mother and in the newborn.</p> <p>Conclusion</p> <p>The prevalence of MS increases with the worsening of glucose tolerance; impaired glycemic profile identifies pregnancies with important metabolic abnormalities even in the presence of a normal OGTT, in patients that are not classified as having GDM.</p

Easting plasma glucose is a useful test for the detection of gestational diabetes

OBJECTIVE - To evaluate fasting plasma glucose as a screening lest for states of gestational diabetes.RESEARCH DESIGN and METHODS - Baseline data of a cohort conducted in general prenatal care units in Brazil, enrolling 5,579 women aged greater than or equal to 20 years with gestational ages of 24-28 weeks at the time of testing and no previous diagnosis of diabetes. A standardized 2-h 75-g oral glucose tolerance test was performed in 5,010 women. Gestational diabetes and its subcategories-diabetes and impaired glucose tolerance-were defined according to the 1994 World Health Organization panel recommendations. We evaluated screening properties of calculated sensitivity and specificity for fasting plasma glucose with receiver operator characteristic curves.RESULTS - for detection of the subcategory diabetes, a fasting plasma glucose of 89 mg/dl jointly maximizes sensitivity (88%) and specificity (78%), identifying 22% of the women as test-positive. for detection of impaired glucose tolerance, a value of 85 mg/dl jointly maximizes sensitivity and specificity (68%), identifying as test-positive 35% of the women. lowering the cut point to 81 mg/dl increases sensitivity to 81%, but decreases specificity to 54%, labeling as test-positive 49% of the women.CONCLUSIONS - Fasting plasma glucose is a useful test for the screening of both subcategories of gestational diabetes, a threshold of 85 mg/dl being an acceptable option. Effective screening for the subcategory diabetes can be achieved using a cut point of 89 mg/dl. If greater emphasis is placed on the detection of impaired glucose tolerance, a lower value, 81 mg/dl, may be needed.Univ Fed Rio Grande Sul, Hosp Clin Porto Alegre, BR-90046900 Porto Alegre, RS, BrazilUniv Fed Rio Grande Sul, Sch Med, Dept Social Med, BR-90046900 Porto Alegre, RS, BrazilPontificia Univ Catolica Rio Grande do Sul, Sch Med, Dept Internal Med, Porto Alegre, RS, BrazilUniversidade Federal de São Paulo, Dept Prevent Med, São Paulo, BrazilMinist Hlth, Rio de Janeiro, BrazilUniversidade Federal de São Paulo, Dept Prevent Med, São Paulo, BrazilWeb of Scienc