What entropy at the edge of chaos?

Numerical experiments support the interesting conjecture that statistical methods be applicable not only to fully-chaotic systems, but also at the edge of chaos by using Tsallis' generalizations of the standard exponential and entropy. In particular, the entropy increases linearly and the sensitivity to initial conditions grows as a generalized exponential. We show that this conjecture has actually a broader validity by using a large class of deformed entropies and exponentials and the logistic map as test cases.Comment: 6 pages, 6 figures, uses ws-procs975x65.cls. Proceedings of the Workshop "Complexity, Metastability and Nonextensivity" held in Erice 20-26 July 2004. New version: minor changes (one reference added, typos corrected, positions of figures changed, some comments added

Ultra high energy photon showers in magnetic field:angular distribution of produced particles

Ultra high energy (UHE) photons can initiate electromagnetic showers in magnetic field. We analyze the two processes that determine the development of the shower, $e^+ e^-$ pair creation and synchrotron radiation, and derive formulae for the angular distribution of the produced particles. These formulae are necessary to study the three-dimensional development of the shower.Comment: RevTex, 13 pages, 4 figure

Fusion reactions in plasmas as probe of the high-momentum tail of particle distributions

In fusion reactions, the Coulomb barrier selects particles from the high-momentum part of the distribution. Therefore, small variations of the high-momentum tail of the velocity distribution can produce strong effects on fusion rates. In plasmas several potential mechanisms exist that can produce deviations from the standard Maxwell-Boltzmann distribution. Quantum broadening of the energy-momentum dispersion relation of the plasma quasi-particles modifies the high-momentum tail and could explain the fusion-rate enhancement observed in low-energy nuclear reaction experiments.Comment: 9 pages in ReVTeX preprint format, 3 figures, to appear in EPJ

Super-Kamiokande hep neutrino best fit: a possible signal of nonmaxwellian solar plasma

The Super-Kamiokande best global fit, which includes data from SNO, Gallium and Chlorine experiments, results in a hep neutrino contribution to the signals that, even after oscillation, is greater than the SSM prediction. The solar hep neutrino flux that would yield this contribution is four times larger than the one predicted by the SSM. Recent detailed calculations exclude that the astrophysical factor S_{hep}(0) could be wrong by such a large factor. Given the reliability of the temperature and densities profiles inside the Sun, this experimental result indicates that plasma effects are important for this reaction. We show that a slight enhancement of the high-energy tail, enhancement that is of the order of the deviations from the Maxwell-Boltzmann distribution expected in the solar core plasma, produces an increment of the hep rate of the magnitude required. We verified that the other neutrino fluxes remain compatible with experimental signals and SSM predictions. Better measurements of the high-energy tail of the neutrino spectrum would improve our understanding of reaction rates in the solar plasma.Comment: 10 pages, ReVTeX4, no figure

Distribuzioni statistiche e reazioni nucleari nei plasmi stellari: conseguenze della non estensivita' sulla produzione dei neutrini solari

Dottorato di ricerca in fisica. 12. ciclo. A.a. 1996-99. Relatori G. Mezzorani e M. Lissia. Coordinatore F. CasulaConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Environmental pollution and health effects in the Quirra area, Sardinia (Italy)

Quirra is a village located in the Italian island of Sardinia, close to a big military base where ballistic missiles and weapons are tested. In the past years and recently, the zone has been called to the attention of the media due to the so-called "Quirra syndrome", an apparently off-normal incidence of illnesses in that zone. The media indicated a possible cause of the above situation in the military use of Depleted Uranium. The paper carries out a statistical assessment to verify if the "Quirra syndrome" exists, in order to evaluate health effects. Moreover, one of the causes of possible pollution - electromagnetic fields due to military warfare use - is addressed, by means also of experimental measurements carried out on site. The results show that, on one side, the so-called "Quirra syndrome" has epidemiological relevance, and, on the other, the measured levels of electromagnetic fields show artificial pollution and require more investigation

Numerical investigation on ship energy efficiency by Monte Carlo simulation

In this article, the authors present a procedure to predict the energy efficiency operational indicator by Monte Carlo simulations, estimating the total ship fuel consumption as a function of displacement and speed considered as random variables. To characterize the probability density function of displacement and speed, a complete series of operating data concerning 2 years of navigation, of a RoPax engaged in a commercial trade in the Mediterranean Sea, were collected and used. </jats:p

Biological Effects of Low-Intensity Electromagnetic Radiation Exposure and the MUOS Case

Recent 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 Niscemi

A New Trend on Electromagnetic Fields (EMF) Risk Assessment

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. 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 children – 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”

Parametric investigation and optimal selection of the hybrid turbocharger system for a large marine four-stroke dual-fuel engine

Hybrid turbochargers can become an attractive solution for new built and retrofitted ship power plants, as their use can result in increasing the plant efficiency and reducing emissions. This study aims at computationally investigating the hybrid turbocharger effects on a large marine dual-fuel four-stroke engine performance and emissions characteristics as well as determining its electrical generator optimal size for the case of a ship power plant considering an actual operating profile. An existing model of a large marine four-stroke dual-fuel engine of the zero/one-dimensional type, which was developed in the commercial software GT-Power, is extended to include the hybrid turbocharger sub-model. This model is subsequently employed to carry out a parametric investigation considering a wide range for the hybrid turbocharger electric motor power. The derived results are analysed to identify the variations of the investigated dual fuel engine performance and emissions parameters in the whole engine operating envelope at both the diesel and gas modes, whilst taking into account the engine and its components operational limits. For the considered annual load profile, the results demonstrate that the optimal nominal size of the hybrid turbocharger electric motor power is 300 kW and leads to an annual energy surplus between 2 to 3% of the annually delivered engine mechanical energy. This study benefits the quantification of the hybrid turbocharger impact on large marine dual fuel four-stroke engines as well as the ship energy efficiency, thus providing useful decision support to facilitate the shipboard implementation of this technology