Decoherence, pointer engineering and quantum state protection

We present a proposal for protecting states against decoherence, based on the engineering of pointer states. We apply this procedure to the vibrational motion of a trapped ion, and show how to protect qubits, squeezed states, approximate phase eigenstates and superpositions of coherent states.Comment: 1 figur

Manutenção e multiplicação de cultivares e sementes genéticas de algodoeiro.

Taxa de cruzamento natural em algodoeiro.bitstream/CNPA/15110/1/CIRTEC45.pd

Hibridação intrespecífica em algodoeiro visando a seleção de cultivares com novas colorações de fibra.

bitstream/CNPA/20779/1/DOC165.pd

Comparing learning objects for effective learning in Mathematics

The too high number of students per class, situation typically found in higher education in Portugal, makes it difficult to adopt an approach were the student work is taken as the center of the learning process. The use of digital contents in this context is helpful for the students to build their own appropriate environment outside the classroom, using all support and learning material built up for that purpose. A fundamental problem we have in Mathematics is that many students are not well prepared in previous concepts. We have been developing and using several kinds of learning objects (LO) for calculus in the recent years, some of them dedicated to recall previous concepts. Among all kinds of contents, students valorize more learning objects that simultaneously challenge them and give them useful feedback. In this paper, we compare the usefulness of different kinds of LO, using computers, in a calculus course for students from several sciences and engineering, with a population of 290 students, based on a survey answered by 40% of them. The learning objects include multiple-choice questions with detailed solutions, quizzes, formative tests, short videos, and others. We present a quantitative analysis comparing different kinds of LO, considering students of several study areas. Together with the quantitative analysis, we add some qualitative considerations based on student’s answers to open questions concerning the learning methodology adopted.publishe

Peroxiredoxins are involved in two independent signalling pathways in the abiotic stress protection in Vitis vinifera

Peroxiredoxins (Prxs) play major roles in preventing oxidative damage and their function is consistent with the presence of Prx isoforms in most, if not all, cellular compartments and their expression is dependent on environmental conditions. The aim of this study was to identify and characterize genes encoding Prxs in Vitis vinifera. Quantitative real time polymerase chain reaction (qRT PCR) was used to determine their response to irradiance, heat, and water stress. We identified seven vvprx genes, two of which were especially responsive to water stress, followed by heat stress, but no major changes were observed after high irradiance. The vvprxIIF targeted to mitochondria was the most responsive to water stress and it might be involved in drought tolerance through H2O2 signalling. The vvprxII-2, a putative PrxII, is targeted to the chloroplasts and was the most responsive to heat stress. It might be related with abscisic acid-dependent thermotoleranc

Distribution of epicenters in the Olami-Feder-Christensen model

We show that the well established Olami-Feder-Christensen (OFC) model for the dynamics of earthquakes is able to reproduce a new striking property of real earthquake data. Recently, it has been pointed out by Abe and Suzuki that the epicenters of earthquakes could be connected in order to generate a graph, with properties of a scale-free network of the Barabasi-Albert type. However, only the non conservative version of the Olami-Feder-Christensen model is able to reproduce this behavior. The conservative version, instead, behaves like a random graph. Besides indicating the robustness of the model to describe earthquake dynamics, those findings reinforce that conservative and non conservative versions of the OFC model are qualitatively different. Also, we propose a completely new dynamical mechanism that, even without an explicit rule of preferential attachment, generates a free scale network. The preferential attachment is in this case a ``by-product'' of the long term correlations associated with the self-organized critical state. The detailed study of the properties of this network can reveal new aspects of the dynamics of the OFC model, contributing to the understanding of self-organized criticality in non conserving models.Comment: 7 pages, 7 figure