Qubit Teleportation and Transfer across Antiferromagnetic Spin Chains

We explore the capability of spin-1/2 chains to act as quantum channels for both teleportation and transfer of qubits. Exploiting the emergence of long-distance entanglement in low-dimensional systems [Phys. Rev. Lett. 96, 247206 (2006)], here we show how to obtain high communication fidelities between distant parties. An investigation of protocols of teleportation and state transfer is presented, in the realistic situation where temperature is included. Basing our setup on antiferromagnetic rotationally invariant systems, both protocols are represented by pure depolarizing channels. We propose a scheme where channel fidelity close to one can be achieved on very long chains at moderately small temperature.Comment: 5 pages, 4 .eps figure

Creating agent platforms to host agent-mediated services that share resources

After a period where the Internet was exclusively filled with content, the present efforts are moving towards services, which handle the raw information to create value from it. Therefore labors to create a wide collection of agent-based services are being perfomed in several projects, such as Agentcities does. In this work we present an architecture for agent platforms named a-Buildings. The aim of the proposed architecture is to ease the creation, installation, search and management of agent-mediated services and the share of resources among services. To do so the a-Buildings architecture creates a new level of abstraction on top of the standard FIPA agent platform specification. Basically, an a-Building is a service-oriented platform which offers a set of low level services to the agents it hosts. We define low level services as those required services that are neccesary to create more complex high level composed services.Postprint (published version

Multilevel Preconditioning of Discontinuous-Galerkin Spectral Element Methods, Part I: Geometrically Conforming Meshes

This paper is concerned with the design, analysis and implementation of preconditioning concepts for spectral Discontinuous Galerkin discretizations of elliptic boundary value problems. While presently known techniques realize a growth of the condition numbers that is logarithmic in the polynomial degrees when all degrees are equal and quadratic otherwise, our main objective is to realize full robustness with respect to arbitrarily large locally varying polynomial degrees degrees, i.e., under mild grading constraints condition numbers stay uniformly bounded with respect to the mesh size and variable degrees. The conceptual foundation of the envisaged preconditioners is the auxiliary space method. The main conceptual ingredients that will be shown in this framework to yield "optimal" preconditioners in the above sense are Legendre-Gauss-Lobatto grids in connection with certain associated anisotropic nested dyadic grids as well as specially adapted wavelet preconditioners for the resulting low order auxiliary problems. Moreover, the preconditioners have a modular form that facilitates somewhat simplified partial realizations. One of the components can, for instance, be conveniently combined with domain decomposition, at the expense though of a logarithmic growth of condition numbers. Our analysis is complemented by quantitative experimental studies of the main components.Comment: 41 pages, 11 figures; Major revision: rearrangement of the contents for better readability, part on wavelet preconditioner adde

On generalizations of the series of Taylor, Lagrange, Laurent and Teixeira

The classical theorems of Taylor, Lagrange, Laurent and Teixeira, are extended from the representation of a complex function F(z), to its derivative F(ν)(z) of complex order ν, understood as either a Liouville (1832) or a Rieman (1847) differintegration (Campos 1984, 1985); these results are distinct from, and alternative to, other extensions of Taylor's series using differintegrations (Osler 1972, Lavoie & Osler & Tremblay 1976). We consider a complex function F(z), which is analytic (has an isolated singularity) at ζ, and expand its derivative of complex order F(ν)(z), in an ascending (ascending-descending) series of powers of an auxiliary function f(z), yielding the generalized Teixeira (Lagrange) series, which includes, for f(z)=z−ζ, the generalized Taylor (Laurent) series. The generalized series involve non-integral powers and/or coefficients evaluated by fractional derivatives or integrals, except in the case ν=0, when the classical theorems of Taylor (1715), Lagrange (1770), Laurent (1843) and Teixeira (1900) are regained. As an application, these generalized series can be used to generate special functions with complex parameters (Campos 1986), e.g., the Hermite and Bessel types

Diversidade de Scarabaeoidea (Insecta: Coleoptera) coletados com armadilha de interceptação de voo no Distrito Federal.

Os representantes da superfamília Scarabaeoidea formam um grupo diverso de organismos que apresentam diferentes hábitos alimentares e comportamento. Esses insetos são normalmente coletados utilizando-se armadilhas de queda ou armadilha luminosa. Entretanto, o uso de armadilha de interceptação de voo pode revelar diferenças na diversidade em Scarabaeoidea, principalmente no Distrito Federal, onde o seu uso é pouco comum. O objetivo desse trabalho foi avaliar a diversidade (riqueza e abundância) de Scarabaeoidea coletados com armadilha de interceptação de voo no Distrito Federal. O estudo foi conduzido em uma área de Cerrado (cerradão) (Planaltina/DF) onde foi instalada uma armadilha de interceptação de voo, composta por uma tela de sombrite preto (1 x 2 m), esticada em posição perpendicular ao solo deixando-se um espaço de ≈10 cm em relação ao solo onde foram encaixadas cinco bandejas plásticas contendo água e detergente. Semanalmente, entre outubro/2013 e abril/2014, os Scarabaeoidea foram coletados e identificados em nível de gênero. Foram coletados 504 espécimes de Scarabaeoidea pertencentes a 3 famílias (Scarabaeidae, Melolonthidae e Geotrupidae) e 24 gêneros (Anomiopus, Anthicheira, Ataenius, Athyreus, Bolbapium, Canthidium, Canthon, Coprophanaeus, Deltochillum, Dendropaemon, Dichotomius, Eurysternus, Eutrichillum, Isonychus, Leucothyreus, Lobogeniates, Lyogenis, Neoathyreus, Ontherus, Oxysternon, Paranomala, Phyllophaga, Plectris e Trizogeniates). Coprophanaeus (n=85) e Oxysternon (n=80) foram os gêneros mais abundantes e juntamente com Deltochillum, Neoathyreus, Eurysternus, Eutrichillum e Dichotomius representaram 84,3% do total coletado. A família Scarabaeidae apresentou maior abundância (n=410) e riqueza (12 gêneros). A maior abundância de Scarabaeoidea foi observada entre novembro e dezembro/2013 (68,8% do total coletado). A armadilha de interceptação de voo se mostrou adequada para coleta de Scarabaeoidea revelando alta diversidade coletada

Current trends regarding protective ileostomy after restorative proctocolectomy

AbstractThe decision to perform a protective ileostomy after ileoanal-pouch anastomosis is con- troversial, and most of the discussion is based on its advantages and disadvantages. Al- though a temporary intestinal diversion has been routinely indicated in most patients, this choice is also associated with complications. The present work aims to review the outcomes after restorative proctocolectomy with or without a protective ileostomy in the treatment of ulcerative colitis and polyposis syndromes. Most papers emphasize that di- version protects against anastomosis leaks; consequently, it may prevent pelvic sepsis and pouch failure. Otherwise, a defunctioning ileostomy may cause morbidity such as dehydra- tion, electrolyte imbalance, psychological problems, skin irritation, anastomosis strictures and intestinal obstruction, among others. There are those who believe that the omission of an ileostomy after the confection of ileal pouches should be reserved for selected patients, with quite acceptable results. The selection criteria should include surgeon, patient and procedure features to ensure a good outcome