Porto Oscillation Code (POSC)

The Porto Oscillation Code (POSC) has been developed in 1995 and improved over the years, with the main goal of calculating linear adiabatic oscillations for models of solar-type stars. It has also been used to estimate the frequencies and eigenfunctions of stars from the pre-main sequence up to the sub-giant phase, having a mass between 0.8 and 4 solar masses. The code solves the linearised perturbation equations of adiabatic pulsations for an equilibrium model using a second order numerical integration method. The possibility of using Richardson extrapolation is implemented. Several options for the surface boundary condition can be used. In this work we briefly review the key ingredients of the calculations, namely the equations, the numerical scheme and the output.Comment: Accepted for publication in Astrophysics and Space Science

Aerosol-assisted metallo-organic chemical vapour deposition of Bi2Se3 films using single-molecule precursors: the crystal structure of bismuth(m) dibutyldiselenocarbamate

The complexes [Bi{Se2CN(C2H5)2}3], [Bi{Se2CN(C4H9)2}3], [Bi{Se2CN(CH3)(C4H9)}3] and [Bi{Se2CN(CH3)(C6H13)}3] have been synthesized and characterized structurally using IR, 1H and 13C NMR. In addition, the crystal structure of [Bi{Se2CN(C4H9)2}3] was determined by single-crystal X-ray diffraction, showing the bismuth centre coordinated to three dialkyldiselenocarbamate ligands through the selenium donor atoms. The Bi(III) compounds were used as precursors for the deposition of Bi2Se3 films on glass substrates through aerosol-assisted metallo-organic chemical vapour deposition (AA-MOCVD)

Representation of Nelson Algebras by Rough Sets Determined by Quasiorders

In this paper, we show that every quasiorder $R$ induces a Nelson algebra $\mathbb{RS}$ such that the underlying rough set lattice $RS$ is algebraic. We note that $\mathbb{RS}$ is a three-valued {\L}ukasiewicz algebra if and only if $R$ is an equivalence. Our main result says that if $\mathbb{A}$ is a Nelson algebra defined on an algebraic lattice, then there exists a set $U$ and a quasiorder $R$ on $U$ such that $\mathbb{A} \cong \mathbb{RS}$.Comment: 16 page

Deutsche Fachsprachen : alte und neue Erfahrungen mit dem Begriff 'Kultur' in den Geisteswissenschaften und im Bereich Deutsch als Fremdsprache

In the last few years, the areas of study of German as Foreign Language and German for Specific Purposes have evidently made an inflationary, and sometimes even inadequate use of concepts related to the adjectives 'cultural' and 'intercultural'. The concepts have often been used so as to serve only to instigate the increase, permanency and dissemination of stereotypes and pre-conceptions. In the Winter 2006/07 Semester, a course called "Fachsprachen und Kultur" was offered on the way the concepts of culture are approached in different fields of study. This paper presents the conclusions of some of the participants on the use of the concept in their primary or secondary areas. The results show that it is urgent and necessary to examine the concepts of culture used in our field of study so that stereotypes do not become the basis for a didactics of German as a Foreign Language.Nas áreas de estudos Alemão como Língua Estrangeira e Alemão para Fins Específicos é evidente, nos últimos anos, o uso inflacionário e até, às vezes, impróprio, de conceitos relacionados aos adjetivos cultural e intercultural. Freqüentemente, os conceitos são usados de tal forma que apenas servem para fomentar o crescimento, a fixação e a difusão de estereótipos e preconceitos. No semestre de inverno 2006/07 foi oferecido um curso denominado "Fachsprachen und Kultur" (Magisterstudiengang Deutsch als Fremdsprache), no qual deveriam ser estudados os conceitos de cultura usados nas diferentes disciplinas. Aqui são apresentadas as conclusões de alguns participantes sobre o uso do conceito nas suas áreas principais ou secundárias. Os resultados mostram que se faz urgente e necessário ocupar-se com os conceitos de cultura que vigoram em nossa disciplina, para que estereótipos não se tornem a base de uma didática do Alemão como Língua Estrangeira

Cavity cooling a single charged nanoparticle

The development of laser cooling coupled with the ability to trap atoms and ions in electromagnetic fields, has revolutionised atomic and optical physics, leading to the development of atomic clocks, high-resolution spectroscopy and applications in quantum simulation and processing. However, complex systems, such as large molecules and nanoparticles, lack the simple internal resonances required for laser cooling. Here we report on a hybrid scheme that uses the external resonance of an optical cavity, combined with radio frequency (RF) fields, to trap and cool a single charged nanoparticle. An RF Paul trap allows confinement in vacuum, avoiding instabilities that arise from optical fields alone, and crucially actively participates in the cooling process. This system offers great promise for cooling and trapping a wide range of complex charged particles with applications in precision force sensing, mass spectrometry, exploration of quantum mechanics at large mass scales and the possibility of creating large quantum superpositions.Comment: 8 pages, 5 figures Updated version includes additional references, new title, and supplementary information include

Fractional ℏ\hbar-scaling for quantum kicked rotors without cantori

Previous studies of quantum delta-kicked rotors have found momentum probability distributions with a typical width (localization length $L$) characterized by fractional $\hbar$-scaling, ie $L \sim \hbar^{2/3}$ in regimes and phase-space regions close to `golden-ratio' cantori. In contrast, in typical chaotic regimes, the scaling is integer, $L \sim \hbar^{-1}$. Here we consider a generic variant of the kicked rotor, the random-pair-kicked particle (RP-KP), obtained by randomizing the phases every second kick; it has no KAM mixed phase-space structures, like golden-ratio cantori, at all. Our unexpected finding is that, over comparable phase-space regions, it also has fractional scaling, but $L \sim \hbar^{-2/3}$. A semiclassical analysis indicates that the $\hbar^{2/3}$ scaling here is of quantum origin and is not a signature of classical cantori.Comment: 5 pages, 4 figures, Revtex, typos removed, further analysis added, authors adjuste