InfoRede: Atendimento Online das Unidades de Informação da Embrapa.

O objetivo deste trabalho foi apresentar uma proposta de sistema em rede, capaz de relacionar todas as bibliotecas do Sistema Embrapa de Bibliotecas (SEB) e outras instituições ligadas à pesquisa em ciências agrárias, para prestação do serviço de referência de forma on line, com o uso de diversas ferramentas da web 2.0 e 3.0

Milheto: Planta para cobertura de solo no sistema de plantio direto em cerrado de Roraima.

bitstream/item/95761/1/052008-milheto-smiderle.pd

Sequential piezoresponse force microscopy and the 'small-data' problem

The term big-data in the context of materials science not only stands for the volume, but also for the heterogeneous nature of the characterization data-sets. This is a common problem in combinatorial searches in materials science, as well as chemistry. However, these data-sets may well be 'small' in terms of limited step-size of the measurement variables. Due to this limitation, application of higher-order statistics is not effective, and the choice of a suitable unsupervised learning method is restricted to those utilizing lower-order statistics. As an interesting case study, we present here variable magnetic-field Piezoresponse Force Microscopy (PFM) study of composite multiferroics, where due to experimental limitations the magnetic field dependence of piezoresponse is registered with a coarse step-size. An efficient extraction of this dependence, which corresponds to the local magnetoelectric effect, forms the central problem of this work. We evaluate the performance of Principal Component Analysis (PCA) as a simple unsupervised learning technique, by pre-labeling possible patterns in the data using Density Based Clustering (DBSCAN). Based on this combinational analysis, we highlight how PCA using non-central second-moment can be useful in such cases for extracting information about the local material response and the corresponding spatial distribution

Non-Linear Relativity in Position Space

We propose two methods for obtaining the dual of non-linear relativity as previously formulated in momentum space. In the first we allow for the (dual) position space to acquire a non-linear representation of the Lorentz group independently of the chosen representation in momentum space. This requires a non-linear definition for the invariant contraction between momentum and position spaces. The second approach, instead, respects the linearity of the invariant contraction. This fully fixes the dual of momentum space and dictates a set of energy-dependent space-time Lorentz transformations. We discuss a variety of physical implications that would distinguish these two strategies. We also show how they point to two rather distinct formulations of theories of gravity with an invariant energy and/or length scale.Comment: 7 pages, revised versio

Maximal Sharing in the Lambda Calculus with letrec

Increasing sharing in programs is desirable to compactify the code, and to avoid duplication of reduction work at run-time, thereby speeding up execution. We show how a maximal degree of sharing can be obtained for programs expressed as terms in the lambda calculus with letrec. We introduce a notion of `maximal compactness' for lambda-letrec-terms among all terms with the same infinite unfolding. Instead of defined purely syntactically, this notion is based on a graph semantics. lambda-letrec-terms are interpreted as first-order term graphs so that unfolding equivalence between terms is preserved and reflected through bisimilarity of the term graph interpretations. Compactness of the term graphs can then be compared via functional bisimulation. We describe practical and efficient methods for the following two problems: transforming a lambda-letrec-term into a maximally compact form; and deciding whether two lambda-letrec-terms are unfolding-equivalent. The transformation of a lambda-letrec-term $L$ into maximally compact form $L_0$ proceeds in three steps: (i) translate L into its term graph $G = [[ L ]]$; (ii) compute the maximally shared form of $G$ as its bisimulation collapse $G_0$; (iii) read back a lambda-letrec-term $L_0$ from the term graph $G_0$ with the property $[[ L_0 ]] = G_0$. This guarantees that $L_0$ and $L$ have the same unfolding, and that $L_0$ exhibits maximal sharing. The procedure for deciding whether two given lambda-letrec-terms $L_1$ and $L_2$ are unfolding-equivalent computes their term graph interpretations $[[ L_1 ]]$ and $[[ L_2 ]]$, and checks whether these term graphs are bisimilar. For illustration, we also provide a readily usable implementation.Comment: 18 pages, plus 19 pages appendi

Vitrines tecnológicas: a informação facilitada sobre patentes na web.

Vitrines tecnológicas ou portfólios de tecnologias são, em geral, websites ou páginas web elaborados por instituições de ensino e pesquisa para disponibilizar informações sobre patentes disponíveis para licenciamento. São produtos alternativos às tradicionais bases de patentes na web. Diante da escassez de relatos de pesquisas a respeito da prática, este estudo tem como objetivos quantificar a ocorrência destes websites sobre tecnologias nas instituições públicas de ensino e pesquisa brasileiras, bem como identificar termos e expressões utilizados na organização da informação.Para tanto, foi criado um instrumento para coleta, registro e análise sistemática dos termos e expressões utilizados nos websites. O método adotado foi de natureza comparativa, para ressaltar diferenças e similaridades entre os produtos. Os dados indicam que 75% das instituições analisadas desenvolveram websites desta natureza,não se tratando, portanto, de um fenômeno isolado. Além disso, falta de padrão foi um aspecto marcante verificado no uso de conceitos para apresentar atributos das tecnologias, bem como para classificá-las. É possível supor que a falta de padrão tenda a dificultar o uso direto, por parte dos usuários, e ainda a oferecer obstáculos à mineração de dados com processamento computacional