Search results for "Statistical"
showing 10 items of 4960 documents
Predicting gully occurrence at watershed scale: Comparing topographic indices and multivariate statistical models
2020
In this study, the ability of five topographic indices to predict the gully trajectories observed in two adjacent watersheds located in Sicily (Italy) was evaluated. Two of these indices, named MSPI and MTWI, as far as we know, have never been employed to this aim. They were obtained by multiplying the stream power index (SPI) and the topographic wetness index (TWI), respectively, by the convergence index (CI). The predictive ability of the topographic indices was measured by using both cut-off independent (AUC: area under the receiver operating characteristic curve) and dependent statistics (Cohen's kappa index κ, sensitivity, specificity). These statistics were calculated also for 100 MAR…
Lévy flights in confining potentials.
2009
We analyze confining mechanisms for L\'{e}vy flights. When they evolve in suitable external potentials their variance may exist and show signatures of a superdiffusive transport. Two classes of stochastic jump - type processes are considered: those driven by Langevin equation with L\'{e}vy noise and those, named by us topological L\'{e}vy processes (occurring in systems with topological complexity like folded polymers or complex networks and generically in inhomogeneous media), whose Langevin representation is unknown and possibly nonexistent. Our major finding is that both above classes of processes stay in affinity and may share common stationary (eventually asymptotic) probability densit…
Comments on an article of Slinn
1989
The discussion of the relationship between concentration fluctuations and residence times is certainly highly welcomed, because it can spread the news of how a simple analytical equation eases the often needed estimate of residence times for trace substances, gases and aerosols in size ranges. However, the treatment by Slinn (1988a) might confuse potential users. To ease the following clarification, I will use Slinn’s notation with C being a concentration and C the mean concentration, whether averaged over the exponentially decaying concentration in time or in distance downwind of a finite-area source. DOI: 10.1111/j.1600-0889.1989.tb00142.x
TWO-LANE TRAFFIC WITH PLACES OF OBSTRUCTION TO TRAFFIC
2004
As the Nagel–Schreckenberg model (NaSch model) became known as a realistic approach to describe traffic flow on single-lane streets, this model was extended to two-lane traffic by several groups. On the base of our two-lane model, we will now investigate the impact of a place of obstruction, e.g., because of road works, on partial fractions, densities and mean velocities.
Response: platelet transcriptome and proteome—relation rather than correlation
2013
We have demonstrated by a detailed statistical analysis of proteome and transcriptome data of human platelets and human cell lines that protein and transcript abundance in platelets, if at all, are only weakly correlated.[1][1] This analysis appears to be in contradiction to previous claims made
Non-wandering sets with non-empty interiors
2003
We study diffeomorphisms of a closed connected manifold whose non-wandering set has a non-empty interior and conjecture that C1-generic diffeomorphisms whose non-wandering set has a non-empty interior are transitive. We prove this conjecture in three cases: hyperbolic diffeomorphisms, partially hyperbolic diffeomorphisms with two hyperbolic bundles, and tame diffeomorphisms (in the first case, the conjecture is folklore; in the second one, it follows by adapting the proof in Brin (1975 Topological transitivity of a certain class of dynamical systems, and flows of frames on manifolds of negative curvature Funct. Anal. Appl. 9 9–19)).We study this conjecture without global assumptions and pro…
THE IMPACT OF ELECTION RESULTS ON THE MEMBER NUMBERS OF THE LARGE PARTIES IN BAVARIA AND GERMANY
2005
In this paper, we investigate the relations between the numbers of members of various parties and their results in the elections in Bavaria and in Germany. Deriving from the finding that there is a strong time-delayed correlation between these data-sets for the two largest parties in Bavaria, we show in a simulation based on the Sznajd model that such a correlation leads to very stable majorities, just as in Bavaria.
A mathematical model of the self-averaging Pitot tube
2005
Abstract Flowmeters with self-averaging Pitot tubes are more and more often applied in practice. Their advantages are practically no additional flow losses, usability in the case of high temperature of fluids and simplicity of fitting. A mathematical model of a self-averaging Pitot tube including the influence of the probe shape, selected constructional features and flow conditions on the quantity of differential pressure gained has been given in this paper. The values and ranges of variations of the coefficients established for the model have been assessed on the basis of the numerically computed velocity and pressure fields around and inside the probe. Velocity and pressure fields were ca…
The predictive power of power-laws: An empirical time-arrow based investigation
2022
The efficient market hypothesis forbids any predictability towards future, but there is no such restriction in the case of reversed-looking approaches. We analyze if this asymmetry in non-predictability is reflected in the statistical features of financial time series. Our study is based on the analysis of the length-distribution of periods with high variability, and introduces time-asymmetric modifications of the method which are capable of revealing differences of the time series in forward and reversed time. We show that the future and reversed-looking time-series possess very similar properties, with some features being distinguishable with our method. Our findings give also evidence of…
A bounded version of bosonic creation and annihilation operators and their related quasi-coherent states
2007
Coherent states are usually defined as eigenstates of an unbounded operator, the so-called annihilation operator. We propose here possible constructions of {\em quasi-coherent states}, which turn out to be {\em quasi} eigenstate of a \underline{bounded} operator related to an annihilation-like operator. We use this bounded operator to construct a sort of modified harmonic oscillator and we analyze the dynamics of this oscillator from an algebraic point of view.