557 research outputs found
Statistical Mechanics Analysis of the Continuous Number Partitioning Problem
The number partitioning problem consists of partitioning a sequence of
positive numbers into two disjoint sets, and
, such that the absolute value of the difference of the sums of
over the two sets is minimized. We use statistical mechanics tools to study
analytically the Linear Programming relaxation of this NP-complete integer
programming. In particular, we calculate the probability distribution of the
difference between the cardinalities of and and show that
this difference is not self-averaging.Comment: 9 pages, 1 figur
Cognitive approaches and optical multispectral data for semi-automated classification of landforms in a rugged mountainous area
This paper introduces a new open source, knowledge-based framework for automatic interpretation of remote sensing images, called InterIMAGE. This framework owns a flexible modular architecture, in which image processing operators can be associated to both root and leaf nodes of the semantic network, which constitutes a differential strategy in comparison to other object-based image analysis platforms currently available. The architecture, main features as well as an overview on the interpretation strategy implemented in InterIMAGE is presented. The paper also reports an experiment on the classification of landforms. Different geomorphometric and textural attributes obtained from ASTER/Terra images were combined with fuzzy logic and drove the interpretation semantic network. Object-based statistical agreement indices, estimated from a comparison between the classified scene and a reference map, were used to assess the classification accuracy. The InterIMAGE interpretation strategy yielded a classification result with strong agreement and proved to be effective for the extraction of landforms
Local dimension and finite time prediction in spatiotemporal chaotic systems
We show how a recently introduced statistics [Patil et al, Phys. Rev. Lett.
81 5878 (2001)] provides a direct relationship between dimension and
predictability in spatiotemporal chaotic systems. Regions of low dimension are
identified as having high predictability and vice-versa. This conclusion is
reached by using methods from dynamical systems theory and Bayesian modelling.
We emphasize in this work the consequences for short time forecasting and
examine the relevance for factor analysis. Although we concentrate on coupled
map lattices and coupled nonlinear oscillators for convenience, any other
spatially distributed system could be used instead, such as turbulent fluid
flows.Comment: 5 pagers, 7 EPS figure
IgY-Technology Applied to Studies of Toxoplasma gondii Infection
In this chapter, we describe relevant aspects of immunoglobulin Y (IgY) technology for Toxoplasma gondii applications, including comparison of avian IgY antibody with mammalian IgG antibody, egg yolk IgY production and isolation procedures, important applications for IgY antibody, and state of the art and perspectives for IgYâtechnology in T. gondii studies. T. gondii is a worldwide public health problem. IgYâtechnology provides an alternative antibody (IgY) to mammalian Immunoglobulin G (IgG) antibody. IgYâtechnology involves the chicken immunization, yolk IgY isolation, antibody characterization, and purified IgY application to several kinds of methods. Immunized chicken transfers a specific IgY from blood to egg yolk. Phylogenetic distance between chickens and mammals influences the generation of antibody repertoires recognizing an antigen profile. IgY is not bound to rheumatoid factor or mammalian complement protein and thus avoids the falseâpositive results. Yolk IgY isolation is carried out by simple procedures that are accessible for any laboratory and, also, for IgY isolation at largeâscale production. IgYâtechnology provides antibodies for proteomic studies, diagnostic assays, and immunotherapy. Although IgYâtechnology is promising, there is a reduced number of investigations with IgY and T. gondii. Future perspectives involve the use of IgYâtechnology for the screening of new T. gondii antigens for diagnostics, therapy, or vaccine, development of innovative techniques for toxoplasmosis diagnostics and may be an immunotherapy for toxoplasmosis
Analytical characterization of the aroma of Tinta Negra Mole red wine: Identification of the main odorants compounds
A method for the simultaneous determination of major and minor volatiles composition in different types (dry, medium dry, sweet and medium sweet) of a young Tinta Negra Mole (TNM) monovarietal red wine from 2003 harvest has been validated. Wine samples preparation includes a dichloromethane liquidâliquid extraction followed by concentration under a nitrogen atmosphere. The extracted fraction was analysed by gas chromatographyâmass spectrometry and give quantitative information for more than 86 analytes whose concentration range from few ÎŒg lâ1 to 259.1 mg lâ1. The method enables high recovery of volatile compounds in wine good linearity with (r2) values higher than 0.980 and good sensitivity. The limits of detection range from 0.003 to 0.534 mg lâ1 and limits of quantification from 0.009 to 1.170 mg lâ1.
The method allows satisfactory determination of more than 80 compounds in the TNM red wines. These wines are characterized by a high content of higher alcohols, ethyl esters, fatty acids and lactones. The levels of sulphur compounds in Tinta Negra Mole medium sweet wines are very low, but they have the highest concentration of carbonyl compounds. Quantitative analysis of the main odorants followed by the determination of aroma index allow us elucidate the aroma of these varieties. On the basis of their odour description and odour threshold, the most powerful odorants of Tinta Negra Mole wines were tentatively established
Intraband transitions in quantum dot-superlattice heterostructures
8 pages, 10 figuresWe present a scheme of adjusting the mid-infrared absorption properties to desired energy transitions in quantum dot-based photodetectors by combining band gap engineering with the self-organized growth of quantum dots. Embedding the self-organized InAs quantum dots into an AlAs/GaAs superlattice enables us to tune the optical transition energy by changing the superlattice period as well as by changing the growth conditions of the dots. Using a one-band envelope function framework, we are able, in a three-dimensional calculation, to predict the absorption spectra of these devices as well as their polarization properties. These calculations further predict a strong impact of the dots on the superlattice minibands. By comparing aligned, periodic dot stacks with nonperiodic dot arrangements within the superlattice, we can experimentally confirm this prediction
SeroprevalĂȘncia para VIH-1 e associação com sĂfilis no COAS (Centro de Orientação e Apoio SorolĂłgico)
Mixing Bandt-Pompe and Lempel-Ziv approaches: another way to analyze the complexity of continuous-states sequences
In this paper, we propose to mix the approach underlying Bandt-Pompe
permutation entropy with Lempel-Ziv complexity, to design what we call
Lempel-Ziv permutation complexity. The principle consists of two steps: (i)
transformation of a continuous-state series that is intrinsically multivariate
or arises from embedding into a sequence of permutation vectors, where the
components are the positions of the components of the initial vector when
re-arranged; (ii) performing the Lempel-Ziv complexity for this series of
`symbols', as part of a discrete finite-size alphabet. On the one hand, the
permutation entropy of Bandt-Pompe aims at the study of the entropy of such a
sequence; i.e., the entropy of patterns in a sequence (e.g., local increases or
decreases). On the other hand, the Lempel-Ziv complexity of a discrete-state
sequence aims at the study of the temporal organization of the symbols (i.e.,
the rate of compressibility of the sequence). Thus, the Lempel-Ziv permutation
complexity aims to take advantage of both of these methods. The potential from
such a combined approach - of a permutation procedure and a complexity analysis
- is evaluated through the illustration of some simulated data and some real
data. In both cases, we compare the individual approaches and the combined
approach.Comment: 30 pages, 4 figure
Forage mass production and grazing loss of sorghum hybrid in response to the density of the sowing and the spacing between planting lines
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