Scaling properties of the Penna model

We investigate the scaling properties of the Penna model, which has become a popular tool for the study of population dynamics and evolutionary problems in recent years. We find that the model generates a normalised age distribution for which a simple scaling rule is proposed, that is able to reproduce qualitative features for all genome sizes.Comment: 4 pages, 4 figure

P-248 Futility and utility of two-stage hepatectomy

Meeting abstract in the European-Society-for-Medical-Oncology (ESMO) 21st World Congress on Gastrointestinal Cancer.info:eu-repo/semantics/publishedVersio

Sharp gene pool transition in a population affected by phenotype-based selective hunting

We use a microscopic model of population dynamics, a modified version of the well known Penna model, to study some aspects of microevolution. This research is motivated by recent reports on the effect of selective hunting on the gene pool of bighorn sheep living in the Ram Mountain region, in Canada. Our model finds a sharp transition in the structure of the gene pool as some threshold for the number of animals hunted is reached.Comment: 5 pages, 4 figure

Transport properties of a two impurity system: a theoretical approach

A system of two interacting cobalt atoms, at varying distances, was studied in a recent scanning tunneling microscope experiment by Bork et. al.[Nature Phys. 7, 901 (2011)]. We propose a microscopic model that explains, for all experimentally analyzed interatomic distances, the physics observed in these experiments. Our proposal is based on the two-impurity Anderson model, with the inclusion of a two-path geometry for charge transport. This many-body system is treated in the finite-U slave boson mean-field approximation and the logarithmic-discretization embedded-cluster approximation. We physically characterize the different charge transport regimes of this system at various interatomic distances and show that, as in the experiments, the features observed in the transport properties depend on the presence of two impurities but also on the existence of two conducting channels for electron transport. We interpret the splitting observed in the conductance as the result of the hybridization of the two Kondo resonances associated with each impurity.Comment: 5 pages, 5 figure

Increased risk for obesity and diabetes with neurodegeneration in developing countries

The incidence of global obesity and Type 2 diabetes has increased and is predicted to rise to 30% of the global population. Diet and lifestyle factors are incapable to resolve the increased incidence for obesity and diabetes in various populations of the world. Developing countries have come to the forefront because of the higher diabetic epidemic. The urbanization may possibly provide an explanation for the global diabetic epidemic. In Western countries the metabolic syndrome and non alcoholic fatty liver disease (NAFLD) have reached 30 % of the population and now at present NAFLD afflicts 20% of developing populations. Western diets and sedentary lifestyles cause metabolic disorders in developing countries which may increase neurodegenerative diseases by the disrupted metabolism of xenobiotics in urban populations. In developing countries access to high calorie diets in urban areas down regulate liver nuclear receptors that are responsible for glucose, lipid and toxicological sensing and interrupt the metabolism of xenobiotics that become toxic to various tissues such as the pancreas, heart, kidney, brain and liver. Xenobiotics in urban areas induce epigenetic changes that involve chromatin remodelling by alterations in transcriptional regulators with modification of histones. Dysfunction of nuclear receptors such as the calorie sensitive sirtuin 1 (Sirt 1) gene involves abnormal nutrient metabolism with insulin resistance, NAFLD, energy balance and circadian rhythm disorders. In obesity and diabetes insulin resistance has been connected to poor xenobiotic metabolism with the toxic affects of increased xenobiotic transport to the brain associated with neurodegeneration. Dietary interventions to increase xenobiotic metabolism are likely to reduce oxidative stress and neuroendocrine disease in developing countries. Prevention programs are an important goal of international health organizations and in developing countries the plans to adapt a healthy diet, active lifestyle and reduced exposure to xenobiotics are important to manage the global epidemic for obesity and diabetes

Caffeine consumption with relevance to Type 3 diabetes and accelerated brain aging

Major interests in caffeine consumption has increased with the alarming increase in the global NAFLD epidemic relevant to increased transport of caffeine to the brain with the induction of Type 3 diabetes. Specific nutritional diets are essential to maintain hepatic caffeine metabolism to facilitate rapid Aβ clearance in the periphery and to maintain the effects of drugs such as statins to reduce toxic Aβ formation not only in Type 3 diabetes but to various neurological diseases. Anti-aging gene Sirt 1 is responsible for brain Aβ and caffeine metabolism and inactivation of Sirt 1 by unhealthy diets is now relevant to Type 3 diabetes and premature brain aging. In the current global NAFLD epidemic caffeine consumption should be carefully controlled to maintain its role as a Sirt 1 modulator with relevance to caffeine regulation of neuron calcium signaling important to circadian glucose and Aβ regulation in Type 3 diabetes