Search results for " Simulation"
showing 10 items of 4034 documents
Genetic structure in the Mediterranean seagrass Posidonia oceanica: disentangling past vicariance events from contemporary patterns of gene flow
2010
The Mediterranean Sea is a two-basin system, with the boundary zone restricted to the Strait of Sicily and the narrow Strait of Messina. Two main population groups are recognized in the Mediterranean endemic seagrass Posidonia oceanica, corresponding to the Western and the Eastern basins. To address the nature of the East-West cleavage in P. oceanica, the main aims of this study were: (i) to define the genetic structure within the potential contact zone (i.e. the Strait of Sicily) and clarify the extent of gene flow between the two population groups, and (ii) to investigate the role of present water circulation patterns vs. past evolutionary events on the observed genetic pattern. To achiev…
Environmental Conditions along Tuna Larval Dispersion: Insights on the Spawning Habitat and Impact on Their Development Stages
2022
Estimated larval backward trajectories of three Tuna species, namely, Atlantic Bluefin Tuna (Thunnus thynnus, Linnaeus, 1758), Bullet Tuna (Auxis Rochei, Risso, 1801) and Albacore Tuna (Thunnus alalunga, Bonnaterre, 1788) in the central Mediterranean Sea, were used to characterize their spawning habitats, and to assess the impact of changes due to the major environmental parameters (i.e., sea surface temperature and chlorophyll-a concentration) on larval development during their advection by surface currents. We assumed that the environmental variability experienced by larvae along their paths may have influenced their development, also affecting their survival. Our results showed that the …
Copy Number Variants and microRNAs in Autism Spectrum Disorders: a whole-genome analysis
2014
In recent years, there has been an increased interest by the scientific community on Autism Spectrum Disorders (ASDs), neurodevelopmental disorders of childhood with an incidence of about 1/160 children [1]. Different studies have indicated a strong genetic basis for autism susceptibility, also supported by the presence of autistic features in several monogenic disorders (e.g.,Fragile X syndrome, Tuberous sclerosis). Since 2007 Copy Number Variants (CNVs) were recognized as important genetic factors in ASD [2]. Studies performed so far have highlighted the pathogenic role of CNVs in terms of dosage change for protein-coding genes and few works have suggested the potential involvement of miR…
Characterization of the terminal column of TRIGA Mark II reactor of Mainz through of alanine pellets.
2017
We have studied the ESR response of alanine pellets with and without gadolinium exposed to the thermal column of the TRIGA Mark II research reactor at the University of Mainz (Germany). The choice of Gd as additive nucleus is due to its very high capture cross section to thermal neutrons and to the possibility for secondary particles produced after interaction with thermal neutrons of releasing their energy in the neighborhood of the reaction site. In particular, it was found that low concentration (5% by weight) of Gd brings about a neutron sensitivity enhancement of more than 10 times without heavily reducing tissue equivalence. Monte Carlo (MC) simulations of both response of alanine and…
An order-adaptive compact approximation Taylor method for systems of conservation laws
2021
Abstract We present a new family of high-order shock-capturing finite difference numerical methods for systems of conservation laws. These methods, called Adaptive Compact Approximation Taylor (ACAT) schemes, use centered ( 2 p + 1 ) -point stencils, where p may take values in { 1 , 2 , … , P } according to a new family of smoothness indicators in the stencils. The methods are based on a combination of a robust first order scheme and the Compact Approximate Taylor (CAT) methods of order 2p-order, p = 1 , 2 , … , P so that they are first order accurate near discontinuities and have order 2p in smooth regions, where ( 2 p + 1 ) is the size of the biggest stencil in which large gradients are n…
Data-driven numerical simulations of the Parker Spiral and interplanetary propagation of solar transients
2023
The accurate reconstruction of the plasma and magnetic field parameters in the ambient interplanetary medium is fundamental to reproduce the interplanetary propagation of solar disturbances such as solar energetic particles (SEPs), stream and corotating interaction regions (SIRs and CIRs), and coronal mass ejections (CMEs), both for understanding the physics of these phenomena and for applications in space weather forecasting. The small-scale features of the ambient solar wind, in fact, affect the evolution, arrival times, and geo-effectiveness of solar transients. The Reverse In situ and MHD Approach (RIMAP) is a hybrid analytical-numerical method to reconstruct the heliosphere on the ecli…
The Boltzmann factor through experiments and simulations
2009
The Boltzmann factor is at the basis of a great amount of thermodynamic and statistical physics, both classical and quantum. It describes the behaviour of natural systems that are exchanging energy with the environment. However, why does the expression have this specific form? The Feynman Lectures on Physics justifies it heuristically by reference to the “exponential atmosphere” example. Thermodynamics textbooks usually give a more or less complete explanation that mainly involves the mathematical analysis, where it is hard to see the logic flow. Moreover, the necessary mathematics is not at the level of high school or college students’ preparation. Here we present an experiments and a simu…
A computational study of point defects and diffusion in enstatite
2009
In order to contribute to the understanding of diffusion processes in enstatite (Mg2Si2O6), we have used atomistic simulation techniques to study point defects in this mineral. We present results for a variety of Scottky and Frenkel defects of all atomic species present in it. We have furthermore calculated the activation energy for magnesium diffusion. We break diffusion down into a succession of hops between neighboring sites. Each hop is associated with a migration energy barrier. By making a series of hops, the diffusing ion may cross the unit cell. The maximum migration energy necessary to attain movement in a direction is the activation energy for diffusion in that direction. The defe…
Computational study of defects in ideal phengite
2009
Phengite is the name of a series designating the “potassic dioctahedral micas between, or close to, the joins muscovite-aluminoceladonite and muscovite-celadonite” (Rieder et al. 1998). These micas play a important role in most petrogenetic reactions occurring in high-pressure (HP) metamorphic environments; they are useful geothermobarometers and participate in reactions as H2O carriers in the subduction zone. In this work we have employed atomistic simulations techniques to model defects, evaluate the most stable defect species and determine the most likely diffusion mechanism in crystals. We have calculated the defect formation energies for vacancies, impurities and interstitials, Frenkel…
Global sensitivity analysis for micropollutant modeling by means of an urban integrated approach
2015
The paper presents the sensitivity analysis of an integrated urban water quality system by means of the global sensitivity analysis (GSA). Specifically, an home-made integrated model developed in previous studies has been modified in order to include the micropollutant assessment (namely, sulfamethoxazole - SMX). The model is able to estimate also the interactions between the three components of the system: sewer system (SS), wastewater treatment plant (WWTP) and the receiving water body (RWB). The analysis has been applied to an experimental catchment nearby Palermo (Italy): the Nocella catchment. Five scenarios each characterized by different combinations of sub-systems (i.e., SS, WWTP an…