27,041 research outputs found
Generalized Onsager-Machlup's theory of thermal fluctuations for non-equilibrium systems
In this work a generalization of Onsager-Machlup's theory of time-dependent
thermal fluctuations of equilibrium systems is proposed, to the case in which
the system relaxes irreversibly along a non-equilibrium trajectory that can be
approximated as a sequence of stationary states. This generalization is
summarized by a canonical description of the dependence of the two-time
correlation function C(t+\tau,t), and of the equal-time correlation function
\sigma(t)= C(t,t) (the covariance of the fluctuations), on the non-equilibrium
relaxation time t
An Axiomatic Characterization of Steenrod's cup- Products
We introduce new formulae for the cup- products on the cochains of spaces.
We prove that any set of choices for the cup- products is isomorphic to the
one defined by our formulae if it is natural, minimal, non-degenerate, and
free. We also show that Steenrod's original set of choices, as well as all of
those induced from operadic and prop theoretic constructions known to the
author satisfy these axioms
Persistence Steenrod modules
We develop the theory of persistence modules equipped with an action of the
Steenrod algebra and effectively incorporate part of the added information into
the persistence computational pipeline
Functional Analysis of Variance for Hilbert-Valued Multivariate Fixed Effect Models
This paper presents new results on Functional Analysis of Variance for fixed
effect models with correlated Hilbert-valued Gaussian error components. The
geometry of the Reproducing Kernel Hilbert Space (RKHS) of the error term is
considered in the computation of the total sum of squares, the residual sum of
squares, and the sum of squares due to the regression. Under suitable linear
transformation of the correlated functional data, the distributional
characteristics of these statistics, their moment generating and characteristic
functions, are derived. Fixed effect linear hypothesis testing is finally
formulated in the Hilbert-valued multivariate Gaussian context considered
Spectral analysis of long range dependence functional time series
Long Range Dependence (LRD) in functional sequences is characterized in the
spectral domain under suitable conditions. Particularly, multifractionally
integrated functional autoregressive moving averages processes can be
introduced in this framework. The convergence to zero in the Hilbert-Schmidt
operator norm of the integrated bias of the periodogram operator is proved.
Under a Gaussian scenario, a weak--consistent parametric estimator of the
long--memory operator is then obtained by minimizing, in the norm of bounded
linear operators, a divergence information functional loss.Comment: 36 page
A finitely presented -prop II: cellular context
We construct, using finitely many generating cell and relations, props in the
category of CW-complexes with the property that their associated operads are
models of the -operad. We use one of these to construct a cellular
-bialgebra structure on the interval and derive from it natural
cellular -coalgebra structures on the geometric realization of
simplicial sets. We use another, a quotient of the first, to relate our
constructions to earlier work of Kaufmann and prove a conjecture of his. This
is the second of two papers in a series, the first investigates analogue
constructions in the category of differential graded modules.Comment: Removed the application to cubical sets. The E-infinity coalgebra
associated to cubical chains can be found in a separate notebook in the
authors webpag
`Tight Binding' methods in quantum transport through molecules and small devices: From the coherent to the decoherent description
We discuss the steady-state electronic transport in solid-state and molecular
devices in the quantum regime. The decimation technique allows a comprehensive
description of the electronic structure. Such a method is used, in conjunction
with the generalizations of Landauer's tunneling formalism, to describe a wide
range of transport regimes. We analize mesoscopic and semiclassical metallic
transport, the metal-insulator transition, and the resonant tunneling regime.
The effects of decoherence on transport is discussed in terms of the
D'Amato-Pastawski model. A brief presentation of the time dependent phenomena
is also included.Comment: 25 pages 20 figure
Sampling basis in reproducing kernel Banach spaces
We present necessary and sufficient conditions to hold true a Kramer type
sampling theorem over semi-inner product reproducing kernel Banach spaces.
Under some sampling-type hypotheses over a sequence of functions on these
Banach spaces it results necessary that such sequence must be a -Riesz
basis and a sampling basis for the space. These results are a generalization of
some already known sampling theorems over reproducing kernel Hilbert spaces
Symplectic or contact structures on Lie Groups
We study left invariant contact forms and left invariant symplectic forms on
Lie groups. We give the classification of all symplectic structures on
nilpotent Lie algebras up the dimension 6.Comment: 18 page
The effect of the spatial domain in FANOVA models with ARH(1) error term
Functional Analysis of Variance (FANOVA) from Hilbert-valued correlated data
with spatial rectangular or circular supports is analyzed, when Dirichlet
conditions are assumed on the boundary. Specifically, a Hilbert-valued fixed
effect model with error term defined from an Autoregressive Hilbertian process
of order one (ARH(1) process) is considered, extending the formulation given in
Ruiz-Medina (2016). A new statistical test is also derived to contrast the
significance of the functional fixed effect parameters. The Dirichlet
conditions established at the boundary affect the dependence range of the
correlated error term. While the rate of convergence to zero of the eigenvalues
of the covariance kernels, characterizing the Gaussian functional error
components, directly affects the stability of the generalized least-squares
parameter estimation problem. A simulation study and a real-data application
related to fMRI analysis are undertaken to illustrate the performance of the
parameter estimator and statistical test derived.Comment: 56 pages (with 11 figures). Supplementary material is also include
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