3,844 research outputs found
BFFT quantization with nonlinear constraints
We consider the method due to Batalin, Fradkin, Fradkina, and Tyutin (BFFT)
that makes the conversion of second-class constraints into first-class ones for
the case of nonlinear theories. We first present a general analysis of an
attempt to simplify the method, showing the conditions that must be fulfilled
in order to have first-class constraints for nonlinear theories but that are
linear in the auxiliary variables. There are cases where this simplification
cannot be done and the full BFFT method has to be used. However, in the way the
method is formulated, we show with details that it is not practicable to be
done. Finally, we speculate on a solution for these problems.Comment: 19 pages, Late
Hamiltonian embedding of the massive noncommutative U(1) theory
We show that the massive noncommutative U(1) can be embedded in a gauge
theory by using the BFFT Hamiltonian formalism. By virtue of the peculiar
non-Abelian algebraic structure of the noncommutative massive U(1) theory,
several specific identities involving Moyal commutators had to be used in order
to make the embedding possible. This leads to an infinite number of steps in
the iterative process of obtaining first-class constraints. We also shown that
the involutive Hamiltonian can be constructed.Comment: 8 pages, Revtex (multicol
Thermodynamics of quantum crystalline membranes
We investigate the thermodynamic properties and the lattice stability of
two-dimensional crystalline membranes, such as graphene and related compounds,
in the low temperature quantum regime . A key role is played by
the anharmonic coupling between in-plane and out-of plane lattice modes that,
in the quantum limit, has very different consequences than in the classical
regime. The role of retardation, namely of the frequency dependence, in the
effective anharmonic interactions turns out to be crucial in the quantum
regime. We identify a crossover temperature, , between classical and
quantum regimes, which is K for graphene. Below , the
heat capacity and thermal expansion coefficient decrease as power laws with
decreasing temperature, tending to zero for as required by the
third law of thermodynamics.Comment: 13 pages, 1 figur
Hamiltonian Embedding of SU(2) Higgs Model in the Unitary Gauge
Following systematically the generalized Hamiltonian approach of Batalin,
Fradkin and Tyutin (BFT), we embed the second-class non-abelian SU(2) Higgs
model in the unitary gauge into a gauge invariant theory. The strongly
involutive Hamiltonian and constraints are obtained as an infinite power series
in the auxiliary fields. Furthermore, comparing these results with those
obtained from the gauged second class Lagrangian, we arrive at a simple
interpretation for the first class Hamiltonian, constraints and observables.Comment: 13 pages, Latex, no figure
Leukemia cutis resembling a flare-up of psoriasis
Abstract
Leukemia cutis represents a skin infiltration by leukemic cells. Clinically it can mimic a wide variety of dermatoses. We describe the case of a 64-year-old man with psoriasis who presented with a 4-day history of erythematous, slightly scaly, asymptomatic plaques distributed on the trunk and upper-extremities, and associated asthenia, myalgias, and anorexia. A skin biopsy revealed a leukemic infiltrate. Studies of peripheral blood and bone marrow provided a diagnosis of acute monocytic leukemia. This case report shows the importance of the clinical suspicion for the diagnosis of leukemia
DHT-based functionalities using hypercubes
Decoupling the permanent identifi er of a node from the node's topology-dependent address is a promising approach toward completely scalable self-organizing networks. Existing solutions use a logical tree-like structure that, although allowing for simple address assignment and management, lead to low route selection flexibility. This clearly results in low routing performance and poor resilience to failures. In this paper, we propose to increase the number of candidate paths by using incomplete hypercubes. We will see that this solution can cover a wide range of applications by adapting to the dynamics of the network1st IFIP International Conference on Ad-Hoc NetWorkingRed de Universidades con Carreras en Informática (RedUNCI
Tensor Coordinates in Noncommutative Mechanics
A consistent classical mechanics formulation is presented in such a way that,
under quantization, it gives a noncommutative quantum theory with interesting
new features. The Dirac formalism for constrained Hamiltonian systems is
strongly used, and the object of noncommutativity plays
a fundamental rule as an independent quantity. The presented classical theory,
as its quantum counterpart, is naturally invariant under the rotation group
.Comment: 12 pages, Late
Anaerobic decolorization of an azo dye by a mixed culture
Wool dyeing wastewater contains xenobiotic compounds that can be removed by biotechnological processes. Studies on various dyes showed that anaerobic processes are suitable to alter azo dyes as a first step of the biodegradation process. These compounds are reduced by anaerobic consortia to aromatic amines and its ultimate degradation can be achieved by a further aerobic treatment. Studies on degradation rate of an wool acid dye were performed in batch systems inoculated with anaerobic biomass. A commercial diazo dye, Acid Red 73, was added to the synthetic medium in which glucose was used as sole carbon source. Results indicated that the Acid Red 73 was partially degraded by a mixed culture of anaerobic bacteria and a decolorization of 90% was obtained. Kinetics studies on removal of the colour showed that the decolorization rate was several times faster than the degradation rate of glucose for a range of dye concentrations between 60 mg/L and 400 mg/L. A first order kinetic model was used for dye concentrations up to 200 mg/L. For higher concentrations a model similar to the Michaelis-Menten equation was better fitted to the experimental data.(undefined
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A dramatic case of Behçet disease successfully treated with infliximab
Behçet disease is a chronic relapsing systemic disease with possible life-threatening presentations. Management of this disease can be challenging and reports of the off-label use of anti-TNFα agents for the treatment of severe manifestations are increasing, with good results. The authors report a case of Behçet disease with a sudden and severe multi-systemic onset successfully treated with infliximab
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