Search results for " Operator"
showing 10 items of 931 documents
La produzione biologica in Italia: un'analisi di scenario ed aspetti legislativi
2010
Gli AA. effettuano un’analisi dello scenario relativo alla produzione bio a livello mondiale, europeo e nazionale. In particolare indagano se in Italia l’evoluzione del numero degli operatori del settore risulta in linea con la ritrovata richiesta dei consumatori di poter disporre di un numero crescente di detti prodotti. Tale analisi è stata ulteriormente approfondita al fine di cogliere le eventuali diversità di diffusione del biologico sul territorio italiano, distinto nelle tre macro-aree geografiche Nord, Centro e Sud negli 2000-2007. Per analizzare tali fenomeni sono stati presi in esame le serie storiche dei dati ufficiali disponibili, aggiornati al 2008, provenienti dal Ministero de…
Local spectral theory for Drazin invertible operators
2016
Abstract In this paper we investigate the transmission of some local spectral properties from a bounded linear operator R, as SVEP, Dunford property (C), and property (β), to its Drazin inverse S, when this does exist.
Property (w) under compact or Riesz perturbations
2010
Si studia la permanenza della proprietà (w), una variante del Teorema di Weyl, nel caso che un operatore sia perturbato da un operatore compatto oppure di Riesz
Pseudo-Bosons from Landau Levels
2010
We construct examples of pseudo-bosons in two dimensions arising from the Hamiltonian for the Landau levels. We also prove a no-go result showing that non-linear combinations of bosonic creation and annihilation operators cannot give rise to pseudo-bosons.
Finite-dimensional pseudo-bosons: a non-Hermitian version of the truncated harmonic oscillator
2018
We propose a deformed version of the commutation rule introduced in 1967 by Buchdahl to describe a particular model of the truncated harmonic oscillator. The rule we consider is defined on a $N$-dimensional Hilbert space $\Hil_N$, and produces two biorhogonal bases of $\Hil_N$ which are eigenstates of the Hamiltonians $h=\frac{1}{2}(q^2+p^2)$, and of its adjoint $h^\dagger$. Here $q$ and $p$ are non-Hermitian operators obeying $[q,p]=i(\1-Nk)$, where $k$ is a suitable orthogonal projection operator. These eigenstates are connected by ladder operators constructed out of $q$, $p$, $q^\dagger$ and $p^\dagger$. Some examples are discussed.
A no-go result for the quantum damped harmonic oscillator
2019
Abstract In this letter we show that it is not possible to set up a canonical quantization for the damped harmonic oscillator using the Bateman Lagrangian. In particular, we prove that no square integrable vacuum exists for the natural ladder operators of the system, and that the only vacua can be found as distributions. This implies that the procedure proposed by some authors is only formally correct, and requires a much deeper analysis to be made rigorous.
Ergonomiskie un psihosociālie riski būvtehnikas ekskavatoru operatoriem un preventīvo pasākumu izstrāde
2015
Ergonomiskie un psihosociālie riski būvtehnikas ekskavatoru operatoriem un preventīvo pasākumu izstrāde. J.Vītoliņš, zinātniskais vadītājs asoc. prof. Dr.chem. Andris Alfreds Spricis. Maģistra darbs 71 lappuse,11 attēli, 27 tabulas, 36 literatūras avoti, 3 pielikumi. Latviešu valodā. Maģistru darbā veikta darba apstākļu analīze ekskavatoru operatoriem, nosakot kaitīgos darba vides riska faktorus un to negatīvo ietekmi uz nodarbinātajiem. Maģistra darba mērķis ir kompleksi novērtēt kaitīgos darba vides riska faktorus un noteikt atbilstošus preventīvos pasākumus riska mazināšanai. Darbs sastāv no ievada, četrām nodaļām, secinājumiem, praktiskām rekomendācijām un pielikumiem. Maģistra darba ga…
A note on faithful traces on a von Neumann algebra
2009
In this short note we give some techniques for constructing, starting from a {\it sufficient} family $\mc F$ of semifinite or finite traces on a von Neumann algebra $\M$, a new trace which is faithful.
Relative cohomology spaces for some osp($n|2$)-modules
2018
International audience; In this work, we describe the H-invariant, so(n)-relative cohomology of a natural class of osp(n|2)-modules M, for n ≠ 2. The Lie superalgebra osp(n|2) can be realized as a superalgebra of vector fields on the superline R1|n. This yields canonical actions on spaces of densities and differential operators on the superline. The above result gives the zero, first, and second cohomology spaces for these modules of densities and differential operators.
A constructive approach of invariants of behavior laws with respect to an infinite symmetry group – Application to a biological anisotropic hyperelas…
2014
Abstract In this paper, six new invariants associated with an anisotropic material made of one fiber family are calculated by presenting a systematic constructive and original approach. This approach is based on the development of mathematical techniques from the theory of invariants: • Definition of the material symmetry group. • Definition of the generalized Reynolds Operator. • Calculation of an integrity basis for invariant polynomials. • Comparison between the new (constructed) invariants and the classical ones.