Search results for "statistical"
showing 10 items of 4960 documents
GAUSSIAN EFFECTIVE POTENTIAL AND ANTIFERROMAGNETISM IN THE HUBBARD MODEL
2012
The Gaussian Effective Potential (GEP) is shown to be a useful variational tool for the study of the magnetic properties of strongly correlated electronic systems. The GEP is derived for a single band Hubbard model on a two-dimensional bi-partite square lattice in the strong coupling regime. At half-filling the antiferromagnetic order parameter emerges as the minimum of the effective potential with an accuracy which improves over RPA calculations and is very close to that achieved by Monte Carlo simulations. Extensions to other magnetic systems are discussed.
Rayleigh and Rice Channels
2011
This chapter contains sections titled: System Theoretical Description of Multipath Channels Formal Description of Rayleigh and Rice Channels Elementary Properties of Rayleigh and Rice Channels Statistical Properties of Rayleigh and Rice Channels Further Reading Appendix 3.A Derivation of the Jakes Power Spectral Density and the Corresponding Autocorrelation Function Appendix 3.B Derivation of the Autocorrelation Function of the Envelope Appendix 3.C Derivation of the Autocovariance Spectrum of the Envelope Under Isotropic Scattering Conditions Appendix 3.D Derivation of the Level‐Crossing Rate of Rice Processes with Different Spectral Shapes of the Underlying Gaussian Random Processes
Teleportation of squeezing: optimization using non-Gaussian resources
2010
We study the continuous-variable quantum teleportation of states, statistical moments of observables, and scale parameters such as squeezing. We investigate the problem both in ideal and imperfect Vaidman-Braunstein-Kimble protocol setups. We show how the teleportation fidelity is maximized and the difference between output and input variances is minimized by using suitably optimized entangled resources. Specifically, we consider the teleportation of coherent squeezed states, exploiting squeezed Bell states as entangled resources. This class of non-Gaussian states includes photon-added and photon-subtracted squeezed states as special cases. At variance with the case of entangled Gaussian re…
Ancestry and demography and descendants of Iron Age nomads of the Eurasian Steppe
2017
During the 1st millennium before the Common Era (BCE), nomadic tribes associated with the Iron Age Scythian culture spread over the Eurasian Steppe, covering a territory of more than 3,500 km in breadth. To understand the demographic processes behind the spread of the Scythian culture, we analysed genomic data from eight individuals and a mitochondrial dataset of 96 individuals originating in eastern and western parts of the Eurasian Steppe. Genomic inference reveals that Scythians in the east and the west of the steppe zone can best be described as a mixture of Yamnaya-related ancestry and an East Asian component. Demographic modelling suggests independent origins for eastern and western g…
A multivariate statistical test for differential expression analysis
2022
AbstractStatistical tests of differential expression usually suffer from two problems. Firstly, their statistical power is often limited when applied to small and skewed data sets. Secondly, gene expression data are usually discretized by applying arbitrary criteria to limit the number of false positives. In this work, a new statistical test obtained from a convolution of multivariate hypergeometric distributions, the Hy-test, is proposed to address these issues. Hy-test has been carried out on transcriptomic data from breast and kidney cancer tissues, and it has been compared with other differential expression analysis methods. Hy-test allows implicit discretization of the expression profi…
THE GOLDMAN CONSTANT FIELD ASSUMPTION - SIGNIFICANCE AND APPLICABILITY CONDITIONS
1986
Ionic transport phenomena in simple, porous membranes can be approximately represented by the Nernst-Planck flux equations and Poisson's equation. In order to solve this set of equations for each particular case, the Goldman constant field assumption is one of the most widely used. In the present paper the significance and the applicability conditions of the above hypothesis is critically examined. and the particular situations where it is exact are shown. These conditions are later verified by solving numerically the electrodiffusion equations. The analysis carried out shows that some of the earlier studies based on asymptotic expansions and numerical solutions should be partially revised.
A critical review on the implementation of static data sampling techniques to detect network attacks
2021
International audience; Given that the Internet traffic speed and volume are growing at a rapid pace, monitoring the network in a real-time manner has introduced several issues in terms of computing and storage capabilities. Fast processing of traffic data and early warnings on the detected attacks are required while maintaining a single pass over the traffic measurements. To palliate these problems, one can reduce the amount of traffic to be processed by using a sampling technique and detect the attacks based on the sampled traffic. Different parameters have an impact on the efficiency of this process, mainly, the applied sampling policy and sampling ratio. In this paper, we investigate th…
A Machine Learning Approach for Fall Detection Based on the Instantaneous Doppler Frequency
2019
Modern societies are facing an ageing problem that is accompanied by increasing healthcare costs. A major share of this ever-increasing cost is due to fall-related injuries, which urges the development of fall detection systems. In this context, this paper paves the way for the development of radio-frequency-based fall detection systems, which do not require the user to wear any device and can detect falls without compromising the user's privacy. For the design of such systems, we present an activity simulator that generates the complex path gain of indoor channels in the presence of one person performing three different activities: slow fall, fast fall, and walking. We have developed a mac…
An optimization approach for efficient management of EV parking lots with batteries recharging facilities
2013
In this paper an optimization approach to devise efficient management strategies for Electric Vehicles parking lots is proposed. A Monte Carlo approach is used to evaluate the load consumption profile for groups of Electric Vehicles showing different features. The Monte Carlo approach allows to combine the different social and economical features affecting the commercial penetration of Electric Vehicles with the technical aspects. The basic feature to be assessed is the initial State Of Charge, which in turn depends on the distance travelled by the vehicle since the last recharge and thus by the usage of the vehicle (private, professional). The model is then used to optimize some objective …
Content quality assessment and acceptance testing in location‐based services
2006
In this paper, we develop and evaluate an approach to assessing the content quality in a location‐based service (LBS). The proposed approach, instead of assessing the quality in absolute terms such as completeness or accuracy, measures the effect that the imperfection of the content is having on the reliability of that specific LBS. We apply the basic ideas from Software Reliability Engineering (SRE), but develop a modification of SRE, 2‐Branch, in order to separate content quality from other factors, such as positioning imprecision, and to reduce the measurement error. In our experimental study, we first compare 2‐Branch to the standard SRE, after which we experimentally analyze some prope…