On the κ\kappa-Dirac Oscillator revisited

This Letter is based on the $\kappa$-Dirac equation, derived from the $\kappa$-Poincar\'{e}-Hopf algebra. It is shown that the $\kappa$-Dirac equation preserves parity while breaks charge conjugation and time reversal symmetries. Introducing the Dirac oscillator prescription, $\mathbf{p}\to\mathbf{p}-im\omega\beta\mathbf{r}$, in the $\kappa$-Dirac equation, one obtains the $\kappa$-Dirac oscillator. Using a decomposition in terms of spin angular functions, one achieves the deformed radial equations, with the associated deformed energy eigenvalues and eigenfunctions. The deformation parameter breaks the infinite degeneracy of the Dirac oscillator. In the case where $\varepsilon=0$, one recovers the energy eigenvalues and eigenfunctions of the Dirac oscillator.Comment: 5 pages, no figures, accepted for publication in Physics Letters

Exchange coupling between magnetic layers across non-magnetic superlattices

The oscillation periods of the interlayer exchange coupling are investigated when two magnetic layers are separated by a metallic superlattice of two distinct non-magnetic materials. In spite of the conventional behaviour of the coupling as a function of the spacer thickness, new periods arise when the coupling is looked upon as a function of the number of cells of the superlattice. The new periodicity results from the deformation of the corresponding Fermi surface, which is explicitly related to a few controllable parameters, allowing the oscillation periods to be tuned.Comment: 13 pages; 5 figures; To appear in J. Phys.: Cond. Matte

Analytical BPS Maxwell-Higgs vortices

We have established a prescription for the calculation of analytical vortex solutions in the context of generalized Maxwell-Higgs models whose overall dynamics is controlled by two positive functions of the scalar field. We have also determined a natural constraint between these functions and the Higgs potential allowing the existence of axially symmetric Bogomol'nyi-Prasad-Sommerfield (BPS) solutions possessing finite energy. Furthermore, when the generalizing functions are chosen suitably, the nonstandard BPS equations can be solved exactly. We have studied some examples, comparing them with the usual Abrikosov-Nielsen-Olesen (ANO) solution. The overall conclusion is that the analytical self-dual vortices are well-behaved in all relevant sectors, strongly supporting the generalized models they belong themselves. In particular, our results mimic well-known properties of the usual (numerical) configurations, as localized energy density, while contributing to the understanding of topological solitons and their description by means of analytical methods.Comment: 8 pages, 4 figure

Dilatonic, Current-Carrying Cosmic String

We study the implications of a scalar-tensorial gravity for the metric of an isolated self-gravitating superconducting cosmic string. These modifications are induced by an arbitrary coupling of a massless scalar field to the usual tensorial field in the gravitational Lagrangian. We derive the metric in the weak-field approximation and we analyse the behaviour of light in this spacetime. We end with some discussions.Comment: 12 pp, Latex, no figures, based on a talk given by M. E. X. Guimaraes at the COSMO 99, 27/9 to 02/10/99, ICTP, Trieste, I

Exponential behavior of the interlayer exchange coupling across non-magnetic metallic superlattices

It is shown that the coupling between magnetic layers separated by non-magnetic metallic superlattices can decay exponentially as a function of the spacer thickness $N$, as opposed to the usual $N^{-2}$ decay. This effect is due to the lack of constructive contributions to the coupling from extended states across the spacer. The exponential behavior is obtained by properly choosing the distinct metals and the superlattice unit cell composition.Comment: To appear in Phys. Rev.

Editorial: Special Issue contributed by the 10th International Chemical and Biological Engineering Conference - CHEMPOR 2008

The 10th International Chemical and Biological Engineering Conference - CHEMPOR 2008, was held in Braga, Portugal, from the 4th to the 6th of September, 2008. The conference was jointly organized by the University of Minho, the “Ordem dos Engenheiros,” and the Institute for Biotechnology and Bioengineeing, with the support of “Sociedade Portuguesa de Qu´ımica” and “Sociedade Portuguesa de Biotecnologia”. The CHEMPOR series traditionally brings together both young and established researchers and end users to discuss recent developments in different areas of Chemical Engineering. The scope of this edition was extended to Biological Engineering research. One of the major core areas of the conference program was life quality, due to the importance that Chemical and Biological Engineering plays in this area. “Integration of Life Sciences & Engineering” and “Sustainable Process-Product Development through Green Chemistry” were two of the leading themes with papers addressing such important issues. This was complemented with additional leading themes including “Advancing the Chemical and Biological Engineering Fundamentals,” “Multi-Scale and/or Multi-Disciplinary Approach to Process-Product Innovation”, “Systematic Methods and Tools for Managing the Complexity”, and “Educating Chemical and Biological Engineers for Coming Challenges.” Papers contributed for this special issue represent a good sample of the important themes that were addressed. This special issue presents a set of fifteen selected research papers, which have undergone the peer-review process of Chemical Product and Process Modeling journal. We wish to thank the authors who have contributed to yield a high scientific standard to this special issue. We also extend our gratefulness to all reviewers, through their dedicated efforts, having assisted us in this task.Uminho -Universidade do Minh

Application of image analysis techniques in biotechnology

Image analysis is commonly used nowadays in a wide range of applications due to the development of faster computers, advanced frame grabbers, and sophisticated software. Although the availability of commercial sophisticated software some efforts have been made at CEB-IBQF in software development using MATLAB programming environment. This programming approach permits to tailor the software to our specific needs. In-house software currently in use and development include: automatic differentiation of flocs and granules through fractal dimension; monitoring methanogenic auto-fluorescence; determination of the reduction in mobility of ciliates exposed to toxics; automatic quantification of filamentous bacteria; automatic counting of viable/non-viable yeasts by epifluorescence microscopy with acridine orange as dying agent. Other developments cover automatic determination of the number of yeast flocs and their size distribution, dynamics of bacterial adhesion, estimation of the tortuosity of porous media, and automatic detection, counting of ink spots in recycled paper simultaneous and monitoring of lactic acid bacteria and yeast during Vinho Verde fermentation using phase contrast microscopy coupled to image analysis