954 research outputs found
Sampling variance and distribution of the D' measure of overall gametic disequilibrium between multiallelic loci
No full textThe development of the theory of estimation of gametic disequilibrium for multiallelic systems is particularly necessary, since a large number of the genetic markers available at present are highly polymorphic multiallelic systems. The D' coefficient is one of the most commonly used measures of the extent of overall disequilibrium between all possible pairs of alleles at two multiallelic loci. Nevertheless, the sampling properties of this measure of overall disequilibrium, are to date, unknown. In this work, we have derived explicit expressions by large-sample theory to compute the approximate sampling variance of D^' between pairs of multiallelic loci, when samples of haplotypes are taken from populations. Formulae for calculating the asymptotic sampling variance were checked by Monte Carlo simulation. In addition, the magnitude of the sampling variance of D^' was investigated under different scenarios of disequilibrium between multiallelic loci. Extensive simulations were also carried out for describing the sampling distribution of D^', conditioned on the sample size, number of alleles and their frequencies, and disequilibrium components. It was found that the sampling distribution of D^' generally approaches well the theoretical normal distribution for experimental sample sizes, particularly when loci have many alleles. Disequilibrium data between microsatellite loci of human chromosome 11p are used for illustration. These investigations increase substantially our knowledge about this widely used measure of overall disequilibrium, which is relevant to evaluate disequilibrium between multiallelic loci in populations
Holonomic quantum computation
No full textIn this brief review we describe the idea of holonomic quantum computation. The idea of geometric phase and holonomy is introduced in a general way and we provide few examples that should help the reader understand the issues involve
LCA approach for the C&D waste management system in different countries of the world
No full textThe main problem with the recovery of construction and demolition (C&D) waste
is the huge amount of recycled aggregates that remain unsold, due, maybe, to
the lack of trust by sector operators. Carry on an environmental assessment
would be a useful method to reveal the advantages in the use of the secondary
resources. Through a literature review, this paper will analyze the application of
Life Cycle tools for evaluating circular strategies in C&D waste management to
compare different scenarios, hypotheses, and approaches adopted in life cycle
assessment (LCA). The comparison will be done between four scientific articles
from different countries (Italy, Spain, Denmark, and Brazil), in which an LCA
analysis regarding C&D waste management has been carried out
Life cycle costing della catena di gestione dei rifiuti da costruzione e demolizione
No full textIl seguente lavoro si pone l’obiettivo di valutare i costi della demolizione selettiva e dell’uso degli aggregati riciclati attraverso l'applicazione della metodologia dell’Environmental Life Cycle Costing (eLCC). L'analisi eLCC ha incluso i costi preliminari, di acquisizione macchinari, operativi e di conferimento relativi all'intera catena di gestione dei rifiuti da costruzione e demolizione (C&D). Sulla base dei risultati ottenuti è stato possibile delineare alcuni scenari prevedendo meccanismi di incentivazione a beneficio della demolizione selettiva e dell’uso degli aggregati riciclati per favorire il raggiungimento di un’economia circolare nel settore delle costruzioni
Studio LCA della catena di gestione dei rifiuti da Costruzione e Demolizione (C&D)
No full textL’obiettivo dello studio LCA qui presentato è duplice. Da un lato lo studio si propone di valutare gli impatti ambientali dell'intera catena di gestione dei rifiuti C&D, dall’altro, di realizzare 24 dataset relativi ai processi di gestione, recupero e smaltimento dei rifiuti da costruzione e demolizione, con particolare riferimento alla regione Lombardia, per l’inserimento nella BDI-LCA di Arcadia
Effects of Lévy noise on the dynamics of sine-Gordon solitons in long Josephson junctions
No full textWe numerically investigate the generation of solitons in currentbiased long Josephson junctions in relation to the superconducting lifetime and the voltage drop across the device. The dynamics of the junction is modelled with a sine-Gordon equation driven by an oscillating field and subject to an external non-Gaussian noise. A wide range of α-stable Levy distributions is considered as a noise source, with varying stability index α and asymmetry parameter β. In junctions longer than a critical length, the mean switching time (MST) from the superconductive to the resistive state assumes a value independent of the device length. Here, we demonstrate that this value is directly related to the mean density of solitons which move into or from the washboard potential minimum corresponding to the initial superconductive state. Moreover, we observe: (i) a connection between the total mean soliton density and the mean potential difference across the junction; (ii) an inverse behaviour of the mean voltage in comparison with the MST, with varying the junction length; (iii) evidence of non-monotonic behaviours, such as stochastic resonant activation and noise-enhanced stability, of the MST versus the driving frequency and noise intensity for different values of α and β; (iv) finally, these non-monotonic behaviours are found to be related to the mean density of the solitons formed along the junction
Multiparameter quantum critical metrology
No full textSingle parameter estimation is known to benefit from extreme sensitivity to parameter changes in quantum critical systems. However, the simultaneous estimation of multiple parameters is generally limited due to the incompatibility arising from the quantum nature of the underlying system. A key question is whether quantum criticality may also play a positive role in reducing the incompatibility in the simultaneous estimation of multiple parameters. We argue that this is generally the case and verify this prediction in paradigmatic quantum many-body systems close to first and second order phase transitions. The antiferromagnetic and ferromagnetic 1-D Ising chain with both transverse and longitudinal fields are analysed across different regimes and close to criticality
Self-consistent triaxial de Zeeuw-Carollo models
No full textWe use the standard method of Schwarzschild to construct
self-consistent solutions for the triaxial
de Zeeuw & Carollo (1996) models with central density cusps.
ZC96 models are triaxial generalizations of
spherical γ-models of Dehnen whose densities vary
as near the center and r-4 at large radii
and hence, possess a central density core for and
cusps for .
We consider four triaxial models from ZC96, two prolate
triaxials: with and 1.5, and
two oblate triaxials: with and 1.5.
We compute 4500 orbits in each model for time periods of .
We find that a large fraction of the orbits in each model are stochastic
by means of their nonzero Liapunov exponents. The stochastic orbits in
each model can sustain regular shapes for ~ or longer,
which suggests that they diffuse slowly through their allowed phase-space.
With the exception of the oblate triaxial models with , our attempts to construct
self-consistent solutions employing only the regular orbits fail for the remaining
three models. However, the self-consistent solutions are found to exist
for all models when the stochastic and regular orbits are treated in the same way
because the mixing-time, ~, is shorter than the integration time,
. Moreover, the “fully-mixed” solutions can also be constructed
for all models when the stochastic orbits are fully mixed at 15 lowest energy shells.
Thus, we conclude that the self-consistent solutions exist for our selected
prolate and oblate triaxial models with and 1.5
Self-consistent triaxial de Zeeuw-Carollo models
No full text[[abstract]]We use the standard method of Schwarzschild to construct self-consistent solutions for the triaxial de Zeeuw & Carollo ( 1996) models with central density cusps. ZC96 models are triaxial generalizations of spherical gamma-models of Dehnen whose densities vary as r(-gamma) near the center and r(-4) at large radii and hence, possess a central density core for gamma = 0 and cusps for gamma > 0. We consider four triaxial models from ZC96, two prolate triaxials: ( p, q) = ( 0.65, 0.60) with. = 1.0 and 1.5, and two oblate triaxials: ( p, q) = ( 0.95, 0.60) with. = 1.0 and 1.5. We compute 4500 orbits in each model for time periods of 10(5)T(D). We find that a large fraction of the orbits in each model are stochastic by means of their nonzero Liapunov exponents. The stochastic orbits in each model can sustain regular shapes for similar to 10(3)T(D) or longer, which suggests that they diffuse slowly through their allowed phase-space. With the exception of the oblate triaxial models with. = 1.0, our attempts to construct self-consistent solutions employing only the regular orbits fail for the remaining three models. However, the self-consistent solutions are found to exist for all models when the stochastic and regular orbits are treated in the same way because the mixing-time, similar to 10(4)T(D), is shorter than the integration time, 105TD. Moreover, the "fully-mixed" solutions can also be constructed for all models when the stochastic orbits are fully mixed at 15 lowest energy shells. Thus, we conclude that the self-consistent solutions exist for our selected prolate and oblate triaxial models with. = 1.0 and 1.5.[[fileno]]2010503010003[[department]]天文
Stabilization by dissipation and stochastic resonant activation in quantum metastable systems: Noise induced phenomena in quantum metastable systems
No full textIn this tutorial paper we present a comprehensive review of the escape dynamics from quantum metastable states in dissipative systems and related noise-induced effects. We analyze the role of dissipation and driving in the escape process from quantum metastable states with and without an external driving force, starting from a nonequilibrium initial condition. We use the Caldeira–Leggett model and a non-perturbative theoretical technique within the Feynman–Vernon influence functional approach in strong dissipation regime. In the absence of driving, we find that the escape time from the metastable region has a nonmonotonic behavior versus the system-bath coupling and the temperature, producing a stabilizing effect in the quantum metastable system. In the presence of an external driving, the escape time from the metastable region has a nonmonotonic behavior as a function of the frequency of the driving, the thermal-bath coupling and the temperature. The quantum noise enhanced stability phenomenon is observed in both systems investigated. Finally, we analyze the resonantly activated escape from a quantum metastable state in the spin-boson model. We find quantum stochastic resonant activation, that is the presence of a minimum in the escape time as a function of the driving frequency. Background and introductory material has been added in the first three sections of the paper to make this tutorial review reasonably self-contained and readable for graduate students and non-specialists from related areas
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