Comment on ``Validity of Feynman's prescription of disregarding the Pauli principle in intermediate states''

In a recent paper Coutinho, Nogami and Tomio [Phys. Rev. A 59, 2624 (1999); quant-ph/9812073] presented an example in which, they claim, Feynman's prescription of disregarding the Pauli principle in intermediate states of perturbation theory fails. We show that, contrary to their claim, Feynman's prescription is consistent with the exact solution of their example.Comment: 1 pag

Qualitative aspects for the cubic nonlinear Schrödinger equations with localized damping: Exponential and polynomial stabilization

AbstractResults of exponential/polynomial decay rates of the energy in L2-level, related to the cubic nonlinear Schrödinger equation with localized damping posed on the whole real line, will be established in this paper. We use Kato's theory and a priori estimates to obtain the result of global well-posedness and we determine exponential/polynomial stabilization combining the ideas of unique continuation due to Zhang, semigroup property and Komornik's approach

COMPARATIVE ANALYSIS OF THE EFFICIENCY OF THERMAL SYSTEMS BUILT WITH REFLECTIVE INSULATORS WITH AND WITHOUT VACUUM

The use of reflective surfaces functioning as thermal insulators has grown significantly over the years. Reflective thermal insulators are materials that have several characteristics such as low emissivity, low absorptivity and high reflectivity in the infrared spectrum. The use of these materials has grown very much lately, since they contain several important radioactive properties that minimize the heat loss of thermal systems and cooling systems that are used to block the heat on the roof of buildings. A system made of three surfaces of 430 stainless steel mirror was built to analyze the influence of reflective surfaces as a way to reduce the heat loss and thereby conserve the energy of a thermal system. The system was analyzed both with and without the presence of vacuum, and then compared with a system that contained glass wool between the stainless steel mirror walls, since this insulator is considered resistive and also broadly used around the world in thermal systems. The reflectivity and emissivity of the surfaces used were also measured in this experiment. A type K thermocouple was fixed on the wall of the system to obtain the temperature of the stainless steel mirror surfaces and to analyze the thermal behavior of each configuration used. The results showed an efficiency of 13% when the reflective surfaces were used to minimize the heat loss of the thermal system. However, the system with vacuum had the best outcome, a 60% efficiency. Both of these were compared to the system made of glass wool as a thermal insulator

A computational model of gene expression in an inducible synthetic circuit

Synthetic biology aims to the rational design of gene circuits with predictable behaviours. Great efforts have been done so far to introduce in the field mathematical models that could facilitate the design of synthetic networks. Here we present a mathematical model of a synthetic gene-circuit with a negative feedback. The closed loop configuration allows the control of transcription by an inducer molecule (IPTG). Escherichia coli bacterial cells were transformed and expression of a fluorescent reporter (GFP) was measured for different inducer levels. Computer model simulations well reproduced the experimental induction data, using a single fitting parameter. Independent genetic components were used to assemble the synthetic circuit. The mathematical model here presented could be useful to predict how changes in these genetic components affect the behaviour of the synthetic circuit

Anomalous electron trapping by localized magnetic fields

We consider an electron with an anomalous magnetic moment g>2 confined to a plane and interacting with a nonzero magnetic field B perpendicular to the plane. We show that if B has compact support and the magnetic flux in the natural units is F\ge 0, the corresponding Pauli Hamiltonian has at least 1+[F] bound states, without making any assumptions about the field profile. Furthermore, in the zero-flux case there is a pair of bound states with opposite spin orientations. Using a Birman-Schwinger technique, we extend the last claim to a weak rotationally symmetric field with B(r) = O(r^{-2-\delta}) correcting thus a recent result. Finally, we show that under mild regularity assumptions the existence can be proved for non-symmetric fields with tails as well.Comment: A LaTeX file, 12 pages; to appear in J. Phys. A: Math. Ge

Efeito de agentes de controle biológico na indução de resistência em videira.

O objetivo deste trabalho foi avaliar o efeito de agentes comerciais de controle biológico como indutores de resistência em videira para o controle do míldio