Temperature effect on (2+1) experimental Kardar-Parisi-Zhang growth

We report on the effect of substrate temperature (T) on both local structure and long-wavelength fluctuations of polycrystalline CdTe thin films deposited on Si(001). A strong T-dependent mound evolution is observed and explained in terms of the energy barrier to inter-grain diffusion at grain boundaries, as corroborated by Monte Carlo simulations. This leads to transitions from uncorrelated growth to a crossover from random-to-correlated growth and transient anomalous scaling as T increases. Due to these finite-time effects, we were not able to determine the universality class of the system through the critical exponents. Nevertheless, we demonstrate that this can be circumvented by analyzing height, roughness and maximal height distributions, which allow us to prove that CdTe grows asymptotically according to the Kardar-Parisi-Zhang (KPZ) equation in a broad range of T. More important, one finds positive (negative) velocity excess in the growth at low (high) T, indicating that it is possible to control the KPZ non-linearity by adjusting the temperature.Comment: 6 pages, 5 figure

Quantum critical point in the spin glass-antiferromagnetism competition in Kondo-lattice systems

A theory is proposed to describe the competition among antiferromagnetism (AF), spin glass (SG) and Kondo effect. The model describes two Kondo sublattices with an intrasite Kondo interaction strength $J_{K}$ and an interlattice quantum Ising interaction in the presence of a transverse field $\Gamma$. The interlattice coupling is a random Gaussian distributed variable (with average $-2J_0/N$ and variance $32 J^{2}/N$) while the $\Gamma$ field is introduced as a quantum mechanism to produce spin flipping. The path integral formalism is used to study this fermionic problem where the spin operators are represented by bilinear combinations of Grassmann fields. The disorder is treated within the framework of the replica trick. The free energy and the order parameters of the problem are obtained by using the static ansatz and by choosing both $J_0/J$ and $\Gamma/J \approx (J_k/J)^2$ to allow, as previously, a better comparison with the experimental findings. The results indicate the presence of a SG solution at low $J_K/J$ and for temperature $T<T_{f}$ ($T_{f}$ is the freezing temperature). When $J_K/J$ is increased, a mixed phase AF+SG appears, then an AF solution and finally a Kondo state is obtained for high values of $J_{K}/J$. Moreover, the behaviors of the freezing and Neel temperatures are also affected by the relationship between $J_{K}$ and the transverse field $\Gamma$. The first one presents a slight decrease while the second one decreases towards a Quantum Critical Point (QCP). The obtained phase diagram has the same sequence as the experimental one for $Ce_{2}Au_{1-x}Co_{x}Si_{3}$, if $J_{K}$ is assumed to increase with $x$, and in addition, it also shows a qualitative agreement concerning the behavior of the freezing and the Neel temperatures.Comment: 11 pages, 3 figures, accepted for publication in J. Phys.

Expert systems within taxation: Competencies for employees

Expert Systems (ES) is increasing its importance, impacting not only personal life but also professional life and its workplace. With ES's growing impact on tax areas, tasks of tax practitioners will change and progress. In addition to financial, legal and tax knowledge, these workers will need to develop and apply technical and analytical knowledge for the use of ES. This research proposal proposes to study the relationship between the presence of ES in taxation and the skills that the labour market imposes. The aim of this study is not only to identify the skills required for technological work within taxation, but also to build and validate a model that contributes to an improvement in the ability to predict workers' ability to adapt to new work demands.info:eu-repo/semantics/publishedVersio

Alternate islands of multiple isochronous chains in wave-particle interactions

We analyze the dynamics of a relativistic particle moving in a uniform magnetic field and perturbed by a standing electrostatic wave. We show that a pulsed wave produces an infinite number of perturbative terms with the same winding number, which may generate islands in the same region of phase space. As a consequence, the number of isochronous island chains varies as a function of the wave parameters. We observe that in all the resonances, the number of chains is related to the amplitude of the various resonant terms. We determine analytically the position of the periodic points and the number of island chains as a function of the wave number and wave period. Such information is very important when one is concerned with regular particle acceleration, since it is necessary to adjust the initial conditions of the particle to obtain the maximum acceleration.Comment: Submitte

Boletim agrometeorológico mensal - dezembro 2000.

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Boletim agrometeorológico mensal - novembro 2000.

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Boletim agrometeorológico mensal - setembro 2000.

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Boletim agrometeorológico mensal - julho 2000.

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Preparing students to apply transversal skills a case study in higher education – 2nd phase

A diverse vocational offer, with a stronger emphasis on key competences, including transversal ones, can provide much needed routes for individuals to improve their qualifications and thus access the labour market. One of the main purposes of the current education and learning efforts is to equip students with competences that are transferable across contexts and that lie beyond approaches to content or areas of knowledge. This study goes through two phases, the first one already published, aimed to devise a profile of transversal skills of the education professional, able to guide the training work in the higher education institutions, support the tasks of evaluation and certification of the said competences and promote the personal and professional development of 1st cycle students A focus group was guide structured based on the objective of this exploratory study (Teaching, learning and evaluation strategies that differentiate the teacher of transversal competences), had five questions and was applied to the traversal skills teachers. The Profile was developed around the following key values and areas of competence: Valuing diversity - difference is considered a resource and a value for education; Working with others - collaboration and teamwork are essential methodologies for all teachers; Professional and personal development - teaching is a learning activity and teachers are responsible for a lifelong learning and Participation - means that all students are involved in learning activities that are meaningful to them. Access to higher education alone is not enough. In this second phase, based on the results previously found, we try to know the perception that the students of transversal competences courses have about this question. To do this, and based on the variables previously identified, we inquired a sample of students, to compare the results obtained with those of the 1st phase and also add to the results of the 1st phase perception about this issue. This study improves the identification and characterization of the requirements to teach transversal competences, and contributes to improve the processes of teacher selection and training.info:eu-repo/semantics/acceptedVersio