Search results for "Order theory"
showing 10 items of 150 documents
Bounded approximation properties via integral and nuclear operators
2010
Published version of an article in the journal:Proceedings of the American Mathematical Society. Also available from the publisher, Open Access
An Efficient Immunization Strategy Using Overlapping Nodes and Its Neighborhoods
2018
International audience; When an epidemic occurs, it is often impossible to vaccinate the entire population due to limited amount of resources. Therefore, it is of prime interest to identify the set of influential spreaders to immunize, in order to minimize both the cost of vaccine resource and the disease spreading. While various strategies based on the network topology have been introduced, few works consider the influence of the community structure in the epidemic spreading process. Nowadays, it is clear that many real-world networks exhibit an overlapping community structure, in which nodes are allowed to belong to more than one community. Previous work shows that the numbers of communit…
A fractional order theory of poroelasticity
2019
Abstract We introduce a time memory formalism in the flux-pressure constitutive relation, ruling the fluid diffusion phenomenon occurring in several classes of porous media. The resulting flux-pressure law is adopted into the Biot’s formulation of the poroelasticity problem. The time memory formalism, useful to capture non-Darcy behavior, is modeled by the Caputo’s fractional derivative. We show that the time-evolution of both the degree of settlement and the pressure field is strongly influenced by the order of Caputo’s fractional derivative. Also a numerical experiment aiming at simulating the confined compression test poroelasticity problem of a sand sample is performed. In such a case, …
A quantitative test of the mode-coupling theory of the ideal glass transition for a binary Lennard-Jones system
1996
Using a molecular dynamics computer simulation we determine the temperature dependence of the partial structure factors for a binary Lennard-Jones system. These structure factors are used as input data to solve numerically the wave-vector dependent mode-coupling equations in the long time limit. Using the so determined solutions, we compare the predictions of mode-coupling theory (MCT) with the results of a previously done molecular dynamics computer simulation [Phys. Rev. E 51, 4626 (1995), ibid. 52, 4134 (1995)]. From this comparison we conclude that MCT gives a fair estimate of the critical coupling constant, a good estimate of the exponent parameter, predicts the wave-vector dependence …
Eta-eta' Photoproduction and the axial isoscalar neutral current coupling
1995
We show that coherentη andη′ photoproduction by means of the Primakoff Effect on the proton depends on the strange component of the neutral axial current coupling. We construct polarization asymmetries that are sensitive to this coupling through theγ−Z interference. Theη′ is not a Goldstone boson of a spontaneously broken chiral symmetry, but a phenomenological analysis of theη andη′ production through chiral perturbation theory allows to calculate the observables of interest. The polarized proton or polarized photon asymmetries are predicted to be close to 10−4 for −q 2∼0.1−0.5 GeV2.
Deformation of the octahedral coordination of the Sb(III) atom in the structure of bis(1,2,4-triazolium) pentachloroantimonate(III) (C2H4N3)2[SbCl5]
2002
In the title compound the [SbCl 6] 3- octahedra show high variations in their Sb-Cl bond lengths and Cl-Sb-Cl angles. There are two crystallographically non-equivalent (C 2H 4N 3) + 1,2,4-triazolium cations in the crystal structure. They are located inside the cavities formed by the [{SbCl 5} 2-] n inorganic structure. The [{SbCl 5} 2-] n chains and (C 2H 4N 3) + cations are connected with each other by the N-H...Cl and C-H...Cl hydrogen bonds. Only two chloride atoms are involved in the N-H...Cl hydrogen bonds. The N-H...Cl interactions are responsible for the changing of geometries of Sb1-Cl2 and Sb1-Cl4 bonds and corresponding Cl-Sb-Cl angles. Their influence on the geometry of [SbCl 6] …
Observable geometric phase induced by a cyclically evolving dissipative process
2006
In a prevous paper (Phys. Rev. Lett. 96, 150403 (2006)) we have proposed a new way to generate an observable geometric phase on a quantum system by means of a completely incoherent phenomenon. The basic idea was to force the ground state of the system to evolve ciclically by "adiabatically" manipulating the environment with which it interacts. The specific scheme we have previously analyzed, consisting of a multilevel atom interacting with a broad-band squeezed vacuum bosonic bath whose squeezing parameters are smoothly changed in time along a closed loop, is here solved in a more direct way. This new solution emphasizes how the geometric phase on the ground state of the system is indeed du…
Integral-geometrical consideration of density matrices
1995
The ensemble N-representability problem for the k-th order reduced density matrix (k-RDM) as well as the problem of reconstruction of the N-particle system density matrices (N-DM) from a given k-RDM are studied. The spatial parts of the k-RDM expansion in terms of spin tensorial operators {Theta}{sub {lambda}} are represented using particular values (at specially chosen {Xi} = {Xi}{sub o}) of the Radon transform D{sub N{lambda}} D{sub N{lambda}}({Xi}) of the N-DM spatial parts (or their sums) D{sub N{lambda}}({chi}{prime}{vert_bar}{chi}{double_prime}) (here, {Xi} is a d-plane in the n-space {Re}{double_prime} of {chi} = ({chi}{prime}, {chi}{double_prime}), with n = 6N, d = 3(N - k), {chi}{p…
Fluorinated Heterocyclic Compounds− The First Example of an Irreversible Ring-Degenerate Rearrangement on Five-Membered Heterocycles by Attack of an …
2004
The reactions of 5-perfluoroalkyl-1,2,4-oxadiazoles 3 with hydroxylamine in DMF give the regioisomeric 3-perfluoroalkyl-1,2,4-oxadiazoles 4 in excellent yields. This process is the first example of ring-degenerate rearrangement (RDR) occurring on five-membered heterocycles by attack of an external bidentate nucleophile, which replaces two heteroatoms of the ring. We suggest that an ANRORC-like mechanism occurs in which the addition of the nucleophilic nitrogen atom (NH2OH) on the C(5) atom of 3 is followed by ring opening and irreversible ring-degenerate closure by attack of the nucleophilic oxygen atom (=NOH) on the C(3) atom of the original ring, realizing an elegant and efficient synthes…
Prime Rings Whose Units Satisfy a Group Identity. II
2003
Abstract Let R be a prime ring and 𝒰(R) its group of units. We prove that if 𝒰(R) satisfies a group identity and 𝒰(R) generates R,then either R is a domain or R is isomorphic to the algebra of n × n matrices over a finite field of order d. Moreover the integers n and d depend only on the group identity satisfed by 𝒰(R). This result has been recently proved by C. H. Liu and T. K. Lee (Liu,C. H.; Lee,T. K. Group identities and prime rings generated by units. Comm. Algebra (to appear)) and here we present a new different proof.