Search results for "Pere"

Random time-changes and asymptotic results for a class of continuous-time Markov chains on integers with alternating rates

2021

We consider continuous-time Markov chains on integers which allow transitions to adjacent states only, with alternating rates. We give explicit formulas for probability generating functions, and also for means, variances and state probabilities of the random variables of the process. Moreover we study independent random time-changes with the inverse of the stable subordinator, the stable subordinator and the tempered stable subodinator. We also present some asymptotic results in the fashion of large deviations. These results give some generalizations of those presented in Di Crescenzo A., Macci C., Martinucci B. (2014).

Magnetic properties of vanadium(IV)-based extended systems: [(VO)3(μ-PO4)2(2,2′-bpy)(μ-OH2)]*1/3H2O and (VO)2H4P2O9

2013

International audience; The magnetic properties of [(VO)3(μ-PO4)2(2,2′-bpy)(μ-OH2)]1/3H2O (1) and (VO)2H4P2O9 (2), a tubular and a layered vanadium(IV) phosphates containing triply oxido bridged VIV dimers, are analyzed considering the Bleaney-Bowers S = 1/2 dimer model. In compound 1 the presence of an additional VIV connected with the VIV dimers through μ1,2-PO43− bridges is described with a Curie-Weiss type correction. This model reproduces the magnetic properties of compound 1 with g = 1.956, Jdim = −102.1 cm−1, θ = −0.4 cm−1 and Nα = 278 × 10−6 emu mol−1. In compound 2, the presence of a small percentage of paramagnetic impurity has to be considered to account for the divergence of χm …

Superexchange-mediated electronic energy transfer in a model dyad

2010

On the basis of time-dependent density functional theory (TD-DFT) calculations coupled to the polarizable continuum model (PCM) and single molecule spectroscopic studies, we provide a detailed investigation of excitation energy transfer within a model bi-chromophoric system where a perylene monoimide (PMI) donor is bridged to a terrylene diimide (TDI) acceptor through a ladder-type pentaphenylene (pPh) spacer. We find that the electronic excitation on the PMI donor significantly extends over the bridge giving rise to a partial charge transfer character and inducing a approximately 3-fold increase in the electronic interaction between the chromophores, which explains the failure of the Först…

Unveiling the Ionic Diels-Alder Reactions within the Molecular Electron Density Theory

2021

The ionic Diels–Alder (I-DA) reactions of a series of six iminium cations with cyclopentadiene have been studied within the Molecular Electron Density Theory (MEDT). The superelectrophilic character of iminium cations, ω &gt

Les limites de la “rhétorique” de Perelman de point de vue réthorique-pragmatique

2013

Analisi storico-filosofica delle origini e dei limiti della "retorica" di Perelman Historical-philosophical survey upon origins and limits of Perelman's rhetoric

Managing soil nitrate with cover crops and buffer strips in Sicilian vineyards

2013

When soil nitrate levels are low, plants suffer nitrogen (N) deficiency but when the levels are excessive, soil nitrates can pollute surface and subsurface waters. Strategies to reduce the nitrate pollution are necessary to reach a sustainable use of resources such as soil, water and plant. Buffer strips and cover crops can contribute to the management of soil nitrates, but little is known of their effectiveness in semiarid vineyards plantations. The research was carried out in the south coast of Sicily (Italy) to evaluate nitrate trends in a vineyard managed both conventionally and using two different cover crops (Triticum durum and Vicia sativa cover crop). A 10 m-wide buffer strip was se…

Bertel Strömmer ja Tampereen kaupunginarkkitehdin toimi vuosina 1918-1939

1997

G1-Blend between a Differentiable Superquadric of Revolution and a Plane or a Sphere Using Dupin Cyclides

2008

In this article, we present a method to perform G1-continuous blends between a differentiable superquadric of revolution and a plane or a sphere using Dupin cyclides. These blends are patches delimited by four lines of curvature. They allow to avoid parameterization problems that may occur when parametric surfaces are used. Rational quadratic Bezier curves are used to approximate the principal circles of the Dupin cyclide blends and thus a complex 3D problem is now reduced to a simpler 2D problem. We present the necessary conditions to be satisfied to create the blending patches and illustrate our approach by a number of superellipsoid/plane and superellipsoid/sphere blending examples.

New construction of algebro-geometric solutions to the Camassa-Holm equation and their numerical evaluation

2011

An independent derivation of solutions to the Camassa-Holm equation in terms of multi-dimensional theta functions is presented using an approach based on Fay's identities. Reality and smoothness conditions are studied for these solutions from the point of view of the topology of the underlying real hyperelliptic surface. The solutions are studied numerically for concrete examples, also in the limit where the surface degenerates to the Riemann sphere, and where solitons and cuspons appear.

Characterization of Leaf Essential Oil Composition of Homozygous and HeterozygousCitrus clementinaHort. Extan. and its Ancestors

2013

Clementine is a natural tangor, resulting from an interspecific cross between mandarin and sweet orange. Gametic embryogenesis, allowing the single-step development of complete homozygous line from the heterozygous parents, increases the efficiency of perennial crop breeding programs. Tri-haploids have been regenerated through pollen embryogenesis (specifically, by anther culture) of Citrus clementina Hort. ex Tan., cv. Nules. Two of them (HOMO1 and HOMO2) have been acclimatized and grafted in vivo in 2000. Research regarding the chemical characteristics of plant regenerated by pollen embryogenesis or gynogenesis are useful to study the “gametoclonal variation”, as well as for further appli…