1,720,987 research outputs found
FKG inequality for Brownian Motion and stochastic differential equations.
No full textThe purpose of this work is to study some possible application of FKG inequality to the Brownian motion and to Stochastic Differential Equations. We introduce a special ordering on the Wiener space and prove the FKG inequality with respect to this ordering. Then we apply this result on the solutions X t of a stochastic differential equation with a positive coefficient σ, we prove that these solutions Xt are increasing with respect to the ordering, and finally we deduce a correlation inequality between the solution of different stochastic equations
Positive and non-positive solutions for an inviscid dyadic model: well-posedness and regularity
No full textWe improve regularity and uniqueness results from the literature for the inviscid dyadic model. We show that positive dyadic is globally well-posed for every rate of growth β of the scaling coefficients kn =2βn . Some regularity results are proved for positive solutions, namely
sup_n n^{−α} k_n^{1/3} X_n (t) < ∞ for a.e. t and sup_n k_n^{1/3-1/3β} Xn (t) ≤ Ct^{−1/3} for all t. Moreover it is shown that under very general hypothesis, solutions become positive after a finite time
The compositional dependence of the saturation surface of H2O+CO2 fluids in silicate melts
No full textThe volatile saturation surface in H2O-CO2-silicate melt systems is modeled by applying thermodynamic equilibrium between gaseous and liquid volatile components. The whole database of existing saturation data in the C-O-H-silicate liquid systems has allowed us to re-calibrate a previously developed fully multicomponent H2O-CO2 saturation model [Papale, P., 1999. Modeling of the solubility of a two-component H2O + CO2 fluid in silicate liquid. Am. Mineral., 84, 477-492]. The new database nearly doubles the previous one, greatly improving the performances of the whole model, which now adopts a significantly lower number of model parameters with respect to the previous calibration. The multicomponent H2O + CO2 saturation model is fully non-ideal, the only assumption being that the excess Gibbs free energy of the silicate mixture can be represented by an expansion of first-order symmetric interaction terms. No a-priori assumption is made on the P-T dependence of the volatile-oxide interaction terms, meaning that no assumption is made on the partial molar volume and enthalpy of the dissolved volatiles. The whole treatment is evaluated by restrictive statistical algorithms, which confirm the model validity on an extended database. The model allows to investigate extensively the dependence of the complex volatile saturation surface on composition. In order to explore the non-linear behaviors implicit in the physics of the dissolution process, the model is employed in a series of calculations aimed at illustrating some of the compositional features of the volatile saturation surface in both one-component and two-component volatile conditions. The results show compositional-dependent minima and maxima, some of which are known from the experiments. Non-ideal behavior is enhanced in two-component fluid phase conditions and pressures above a few hundreds MPa, where calculated isobaric H2O-CO2 saturation curves reveal the possible existence of a maximum in CO2 saturation at non-zero H2O contents. Due to the compositional dependence of the volatile saturation surface, it is outlined the important role played by redox conditions, especially in iron-rich melt systems like basalts
Stochastic inviscid shell models: well-posedness and anomalous dissipation
No full textIn this paper we study a stochastic version of an inviscid shell model of turbulence with multiplicative noise. The deterministic counterpart of this model is quite general and includes inviscid GOY and Sabra shell models of turbulence. We prove global weak existence and uniqueness of solutions for any finite energy initial condition. Moreover energy dissipation of the system is proved in spite of its formal energy conservation
Global regularity for a slightly supercritical hyperdissipative Navier-Stokes system
Full text linkWe prove global existence of smooth solutions for a slightly supercritical hyperdissipative Navier–Stokes
under the optimal condition on the correction to the dissipation. This proves a conjecture formulated
by Tao
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Analytical and numerical results for the Rational Large Eddy simulation model
No full textIn this paper we analyze the Rational Large Eddy Simulation model. We start by introducing the system of partial differential equations we shall consider, together with its derivation. Then, we prove a result of full regularity for strong solutions in the space periodic setting. We also construct some exact solutions useful for the numerical benchmarking and finally we provide the results of some numerical experiments we performed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Strong existence and uniqueness of the stationary distribution for a stochastic inviscid dyadic model
Full text linkWe consider an inviscid stochastically forced dyadic model, where the additive noise acts only on the first component. We prove that a strong solution for this problem exists and is unique by means of uniform energy estimates. Moreover, we exploit these results to establish strong existence and uniqueness of the stationary distribution
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