1,720,976 research outputs found
Biological Effects of Low-Intensity Electromagnetic Radiation Exposure and the MUOS Case
No full textRecent and very recent scientific literature shows that both biological and sanitary effects of EMF radiations - from the extremely low frequency magnetic fields (ELF/EMF) to the high and very high radiofrequencies (RF/EMF) - are clearly established and occur even at very low exposure levels. Overall, there are now almost 4.000 experimental studies that report a variety of short and medium-term effects of EMF, which support the biological plausibility of the increased risks of their long-term genotoxic, carcinogenic and neurodegenerative consequences on exposed human populations. For instance, EMF exposures of cultured mammaliant cells, experimental animals and human subjects may induce genetic and epigenetic effects, such as single and double strand DNA damages, chromosomal aberrations, micronuclei, sister-chromatid exchanges, alteration or loss of the DNA damage repair processes, abnormal DNA transcription and protein functions, etc.; stimulation of heat-shock protein synthesis; inhibition of apoptosis (programmed cell death); damages to cellular macromolecules due to the impairment of the inactivation of free radicals and the consequent oxidative stress on account of the inhibition of melatonin syntesis and the stimulation of the Fenton's reaction; modification of the cell membrane permeability and the consequent alteration of the flow of biologically important ions such as Calcium; alteration of the function of the immune system; serious impacts on sperm morphology and functional with consequent effects on the offspring; alterations of the brain functions as a consequence of the interference of a EMF on cerebral frequencies, etc. Many of these bioeffects can reasonably be presumed to result in adverse health effects if the exposures are prolonged or chronic. This is because they interfere with normal body processes (disrupt homeostasis), prevent the body from healing damaged DNA, produce immune system imbalances, metabolic disruption and lower resilience to disease across multiple pathways. Essential body processes can eventually be disabled by incessant external stresses (from system-wide electrophysiological interference) and lead to pervasive impairment of behavioural metabolic and reproductive functions. There is good evidence to suggest that many toxic exposures to the fetus and very young child have especially detrimental consequences depending on when they occur during critical phases of growth and development (time windows of critical development), or where such exposures may lay the seeds of health harm that develops even decades later. Existing FCC and ICNIRP public safety limits are not sufficiently protective of public health, in particular for the young subjects - embryos, fetuses, neonates, very young childs - and for those which are exposed to extremely high ELF and RF/EMF levels. Sufficient evidence comes from epidemiological studies of an increased risk from exposure to EMF of adverse acute effects and even long-term carcinogenic effects that cannot be attributed to chance, bias or confounding. Therefore, according to the rules of IARC, such exposures can be classified at least as Group 2 "probable carcinogenic agents for humans". The MUOS (Mobile User Objective System) is a military radio-transmission system that is proposed for installation close to the small village of Niscemi (Sicily, Italy). Ours study presents the results of electromagnetic radiation models in that area and documents the scientific sanitary reasons why the MUOS system should not be installed in Niscem
Statistical descriptions of nonlinear systems at the onset of chaos
No full textEnsemble of initial conditions for nonlinear maps can be described in terms of entropy. This ensemble entropy shows an
asymptotic linear growth with rate K. The rate K matches the logarithm of the corresponding asymptotic sensitivity to
initial conditions l. The statistical formalism and the equality K 1⁄4 l can be extended to weakly chaotic systems by suitable
and corresponding generalizations of the logarithm and of the entropy. Using the logistic map as a test case we consider a
wide class of deformed statistical description which includes Tsallis, Abe and Kaniadakis proposals. The physical criterion
of finite-entropy growth K strongly restricts the suitable entropies. We study how large is the region in parameter space
where the generalized description is useful
Biological and Sanitary Effects of the Exposures to Non Ionizing Electromagnetic Fields (EMF) and the MUOS Case
No full textRecent and very recent scientific literature shows that both biological and sanitary effects of EMF radiations – from the extremely low frequency magnetic fields (ELF/EMF) to the high and very high radiofrequencies (RF/EMF) – are clearly established and occur even at very low exposure levels. Overall, there are now almost 4.000 experimental studies that report a variety of short and medium-term effects of EMF, which support the biological plausibility of the increased risks of their long-term genotoxic, carcinogenic and neurodegenerative consequences on exposed human populations. For instance, EMF exposures of cultured mammaliant cells, experimental animals and human subjects may induce genetic and epigenetic effects, such as single and double strand DNA damages, chromosomal aberrations, micronuclei, sister-chromatid exchanges, alteration or loss of the DNA damage repair processes, abnormal DNA transcription and protein functions, etc.; stimulation of heat-shock protein synthesis; inhibition of apoptosis (programmed cell death); damages to cellular macromolecules due to the impairment of the inactivation of free radicals and the consequent oxidative stress on account of the inhibition of melatonin syntesis and the stimulation of the Fenton’s reaction; modification of the cell membrane permeability and the consequent alteration of the flow of biologically important ions such as Calcium; alteration of the function of the immune system; serious impacts on sperm morphology and functional with consequent effects on the offspring; alterations of the brain functions as a consequence of the interference of a EMF on cerebral frequencies, etc. Many of these bioeffects can reasonably be presumed to result in adverse health effects if the exposures are prolonged or chronic. This is because they interfere with normal body processes (disrupt homeostasis), prevent the body from healing damaged DNA, produce immune system imbalances, metabolic disruption and lower resilience to disease across multiple pathways
Numerical study of the oscillatory convergence to the attractor at the edge of chaos
No full textThis paper compares three different types of “onset of chaos” in the logistic and generalized logistic map: the Feigenbaum attractor at the end of the period doubling bifurcations; the tangent bifurcation at the border of the period three window; the transition to chaos in the generalized logistic with inflection 1/2 (x n+1 =1-μx n 1/2 ), in which the main bifurcation cascade, as well as the bifurcations generated by the periodic windows in the chaotic region, collapse in a single point. The occupation number and the Tsallis entropy are studied. The different regimes of convergence to the attractor, starting from two kinds of far-from-equilibrium initial conditions, are distinguished by the presence or absence of log-log oscillations, by different power-law scalings and by a gap in the saturation levels. We show that the escort distribution implicit in the Tsallis entropy may tune the log-log oscillations or the crossover times. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 200605.10.-a Computational methods in statistical physics and nonlinear dynamics, 05.45.-a Nonlinear dynamics and nonlinear dynamical systems, 05.45.Pq Numerical simulations of chaotic systems ,
Entropy production and pesin-like identity at the onset of chaos
No full textAsymptotically entropy of chaotic systems increases linearly and the sensitivity to initial condi- tions is exponential with time: these two behaviors are related. Such relationship is the analogous of and under specific conditions has been shown to coincide with the Pesin identity. Numerical evi- dences support the proposal that the statistical formalism can be extended to the edge of chaos by using a specific generalization of the exponential and of the Boltzmann-Gibbs entropy. We extend this picture and a Pesin-like identity to a wide class of deformed entropies and exponentials using the logistic map as a test case. The physical criterion of finite-entropy growth strongly restricts the suitable entropies. The nature and characteristics of this generalization are clarified
Weak insensitivity to initial conditions at the edge of chaos in the logistic map
No full textWe extend existing studies of weakly sensitive points within the framework of Tsallis non-extensive thermodynamics to include weakly insensitive points at the edge of chaos. Analyzing tangent points of the logistic map we have verified that the generalized entropy with suitable entropic index q correctly describes the approach to the attractor. © 2004 Elsevier B.V. All rights reserved
Thermal distributions in stellar plasmas, nuclear reactions and solar neutrinos
No full textThe physics of nuclear reactions in stellar plasma is reviewed with special emphasis on the importance of the velocity distribution of ions. Then the properties (density and temperature) of the weak-coupled solar plasma are analysed, showing that the ion velocities should deviate from the Maxwellian distribution and could be better described by a weakly-nonextensive (|q-1| < 0.02) Tsallis' distribution. We discuss concrete physical frameworks for calculating this deviation: the introduction of higher-order corrections to the diffusion and friction coefficients in the Fokker-Planck equation, the influence of the electric-microfield stochastic distribution on the particle dynamics, a velocity correlation function with long-time memory arising from the coupling of the collective and individual degrees of freedom. Finally, we study the effects of such deviations on stellar nuclear rates, on the solar neutrino fluxes, and on the pp neutrino energy spectrum, and analyse the consequences for the solar neutrino problem
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