Página 14 dos resultados de 3305 itens digitais encontrados em 0.008 segundos

## Improving the Performance of maxRPC

Balafoutis, Thanasis; Paparrizou, Anastasia; Stergiou, Kostas; Walsh, Toby
Tipo: Artigo de Revista Científica
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Max Restricted Path Consistency (maxRPC) is a local consistency for binary constraints that can achieve considerably stronger pruning than arc consistency. However, existing maxRRC algorithms suffer from overheads and redundancies as they can repeatedly perform many constraint checks without triggering any value deletions. In this paper we propose techniques that can boost the performance of maxRPC algorithms. These include the combined use of two data structures to avoid many redundant constraint checks, and heuristics for the efficient ordering and execution of certain operations. Based on these, we propose two closely related algorithms. The first one which is a maxRPC algorithm with optimal O(end^3) time complexity, displays good performance when used stand-alone, but is expensive to apply during search. The second one approximates maxRPC and has O(en^2d^4) time complexity, but a restricted version with O(end^4) complexity can be very efficient when used during search. Both algorithms have O(ed) space complexity. Experimental results demonstrate that the resulting methods constantly outperform previous algorithms for maxRPC, often by large margins, and constitute a more than viable alternative to arc consistency on many problems.

## A computed line list for the H2D+ molecular ion

Sochi, Taha; Tennyson, Jonathan
Tipo: Artigo de Revista Científica
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A comprehensive, calculated line list of frequencies and transition probabilities for the singly deuterated isotopologue of H3+, H2D+, is presented. The line list, called ST1, contains over 22 million rotational-vibrational transitions occurring between more than 33 thousand energy levels; it covers frequencies up to 18500 cm-1. All energy levels with rotational quantum number, J, up to 20 are considered, making the line list useful for temperatures up to at least 3000 K. About 15% of these levels are fully assigned with approximate rotational and vibrational quantum numbers. The list is calculated using a previously proposed, high accuracy, ab initio model and consistency checks are carried out to test and validate the results. These checks confirm the accuracy of the list. A temperature-dependent partition function, valid over a more extended temperature range than those previously published, and cooling function are presented. Temperature-dependent synthetic spectra in the frequency range 0 - 10000 cm-1 are also given.; Comment: 7 pages, 3 figures, 5 tables

## Super Mario's prison break -- a proposal of object-intelligent-feedback-based classical Zeno and anti-Zeno effects

Gu, Shi-Jian
Tipo: Artigo de Revista Científica
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Super Mario is imprisoned by a demon in a finite potential well. He can escape from the well with the help of a flight of magic stairs floating in the space. However, the hateful demon may occasionally check his status. At that time, he has to make a judgement of either jumping to the inside ground immediately in order to avoid the discovery of his escape intention, or speeding up his escape process. Therefore, if the demon checks him too frequently such that there is no probability for him to reach the top of the barrier, he will be always inside the well, then a classical Zeno effect occurs. On the other hand, if the time interval between two subsequent checks is large enough such that he has a higher probability of being beyond the demon's controllable range already, then the demon's check actually speeds up his escape and a classical anti-Zeno effect takes place.; Comment: 4 pages, 4 figures

## Message passing algorithms for non-linear nodes and data compression

Ciliberti, S.; Mezard, M.; Zecchina, R.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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The use of parity-check gates in information theory has proved to be very efficient. In particular, error correcting codes based on parity checks over low-density graphs show excellent performances. Another basic issue of information theory, namely data compression, can be addressed in a similar way by a kind of dual approach. The theoretical performance of such a Parity Source Coder can attain the optimal limit predicted by the general rate-distortion theory. However, in order to turn this approach into an efficient compression code (with fast encoding/decoding algorithms) one must depart from parity checks and use some general random gates. By taking advantage of analytical approaches from the statistical physics of disordered systems and SP-like message passing algorithms, we construct a compressor based on low-density non-linear gates with a very good theoretical and practical performance.; Comment: 13 pages, European Conference on Complex Systems, Paris (Nov 2005)

## Semantic Guidance and Feedback for the Construction of Specifications and Implementations

Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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The problem of writing a specification which accurately reflects the intent of the developer has long been recognized as fundamental. We propose a method and a supporting tool to write and check a specification and an implementation using a set of use cases, \ie input-output pairs that the developer supplies. These are instances of both good (correct) and bad (incorrect) behavior. We assume that the use cases are accurate, as it is easier to generate use cases than to write an accurate specification. We incrementally construct a specification (precondition and postcondition) based on semantic feedback generated from these use cases. We check the accuracy of the constructed specification using two proposed algorithms. The first algorithm checks the accuracy of the specification against an automatically generated specification from a supplied finite domain of use cases. The second checks the accuracy of the specification via reducing its domain to a finite yet equally satisfiable domain if possible. When the specification is mature, we start to also construct a program that satisfies the specification. However, our method makes provision for the continued modification of the specification, if needed. We illustrate our method with two examples; linear search and text justify.

## Interprocedural Type Specialization of JavaScript Programs Without Type Analysis

Chevalier-Boisvert, Maxime; Feeley, Marc
Tipo: Artigo de Revista Científica
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Dynamically typed programming languages such as Python and JavaScript defer type checking to run time. VM implementations can improve performance by eliminating redundant dynamic type checks. However, type inference analyses are often costly and involve tradeoffs between compilation time and resulting precision. This has lead to the creation of increasingly complex multi-tiered VM architectures. Lazy basic block versioning is a simple JIT compilation technique which effectively removes redundant type checks from critical code paths. This novel approach lazily generates type-specialized versions of basic blocks on-the-fly while propagating context-dependent type information. This approach does not require the use of costly program analyses, is not restricted by the precision limitations of traditional type analyses. This paper extends lazy basic block versioning to propagate type information interprocedurally, across function call boundaries. Our implementation in a JavaScript JIT compiler shows that across 26 benchmarks, interprocedural basic block versioning eliminates more type tag tests on average than what is achievable with static type analysis without resorting to code transformations. On average, 94.3% of type tag tests are eliminated...

## Orbital roulette: a new method of gravity estimation from observed motions

Beloborodov, Andrei M.; levin, Yuri
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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The traditional way of estimating the gravitational field from observed motions of test objects is based on the virial relation between their kinetic and potential energy. We find a more efficient method. It is based on the natural presumption that the objects are observed at a random moment of time and therefore have random orbital time phases. The proposed estimator, which we call "orbital roulette", checks the randomness of the phases. The method has the following advantages: (1) It estimates accurately Keplerian (point-mass) potentials as well as non-Keplerian potentials where the unknown gravitating mass is distributed in space. (2) It is a complete statistical estimator: it checks a trial potential and accepts it or rules it out with a certain significance level; the best-fit measurement is thus supplemented with error bars at any confidence level. (3) It needs no a priori assumptions about the distribution of orbital parameters of the test bodies. We test our estimator with Monte-Carlo-generated motions and demonstrate its efficiency. Useful applications include the Galactic Center, dark-matter halo of the Galaxy, and clusters of stars or galaxies.; Comment: 30 pages, accepted to ApJ

## Coset conformal blocks and N=2 gauge theories

Wyllard, Niclas
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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It was recently suggested that the su(N)_k+su(N)_p/su(N)_{k+p} coset conformal field theories should be related to N=2 SU(N) gauge theories on R^4/Z_p. In this paper we study various aspects of this proposal. We perform explicit checks of the relation for (N,p)=(2,4), where the symmetry algebra of the coset is the so called S_3 parafermion algebra. Even though the symmetry algebra of the coset is unknown for generic (N,p) models, we manage to perform non-trivial checks in the general case by using knowledge of the Kac determinant of the coset CFT. We also find evidence that the conformal blocks of the (N,p) model should factorise into a certain product of p (N,1) conformal blocks. Precisely this structure is present in the instanton partition function on R^4/Z_p.; Comment: 24 pages

## Consistency tests of AMPCALCULATOR and chiral amplitudes in SU(3) Chiral Perturbation Theory: A tutorial based approach

Ananthanarayan, B.; Das, Diganta; Imsong, I. Sentitemsu
Tipo: Artigo de Revista Científica
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Ampcalculator is a Mathematica based program that was made publicly available some time ago by Unterdorfer and Ecker. It enables the user to compute several processes at one-loop (upto $O(p^4)$) in SU(3) chiral perturbation theory. They include computing matrix elements and form factors for strong and non-leptonic weak processes with at most six external states. It was used to compute some novel processes and was tested against well-known results by the original authors. Here we present the results of several thorough checks of the package. Exhaustive checks performed by the original authors are not publicly available, and hence the present effort. Some new results are obtained from the software especially in the kaon odd-intrinsic parity non-leptonic decay sector involving the coupling $G_{27}$. Another illustrative set of amplitudes at tree level we provide is in the context of $\tau$-decays with several mesons including quark mass effects, of use to the BELLE experiment. All eight meson-meson scattering amplitudes have been checked. Kaon-Compton amplitude has been checked and a minor error in published results has been pointed out. This exercise is a tutorial based one, wherein several input and output notebooks are also being made available as ancillary files on the arXiv. Some of the additional notebooks we provide contain explicit expressions that we have used for comparison with established results. The purpose is to encourage users to apply the software to suit their specific needs. An automatic amplitude generator of this type can provide error-free outputs that could be used as inputs for further simplification...

## Estrutura interna de testes de cohecimento em Física : um exemplo em mecânica

da Silveira, F. Lang; Moreira, Marco Antonio; Axt, R.
Tipo: Artigo de Revista Científica Formato: application/pdf
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Research findings are presented concerning the internal structure analysis of a multiple choice test constructed to detect whether or not the student has the Newtonian conception of the interrelationship between force and motion. These findings show that the test has two different but related factors: one subset of items checks students' ability to identify forces in certain physical situations according to the Newtonian view while another subset checks whether or not they relate the resultant force with acceleration. In addition, the analysis also shows that the two subsets have slightly different predicting power concerning student performance in mechanics. This kind of analysis might be very relevant for teacher's work regarding learning evaluation.

## A Hierarchical Design Rule Checker

Whitney, Telle
Fonte: California Institute of Technology Publicador: California Institute of Technology
Tipo: Report or Paper; PeerReviewed Formato: other; application/postscript
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This thesis describes a new approach to the problem of Geometrical Design Rule Checking (DRC). Previous DRC implementations have dealt with fully instantiated geometrical artwork. As the complexity of VLSI increases, it becomes infeasible to analyze the vast amounts of information present in a fully instantiated design. The DRC algorithm presented here introduces an approach that exploits the structural hierarchy of a design in order to reduce the computational complexity of the geometrical tests that need to be made. The technique described is also app1icable to other types of design checking such as circuit extraction, functional verification and electrical rule verification. A new DRC algorithm has been developed that, by making use of the structure inherent in a hierarchical design, eliminates many redundant design rule checks. In this approach there are two places where possible design rule violations may occur. The first is within a symbol definition. The second is the area where two symbols interact. The algorithm checks a given definition only once, and then examines how interactions within each new environment where the definition is placed modify the original definition. A note is made after each interaction has been scrutinized...

## Studies of response to earthquake ground motion

Fonte: California Institute of Technology Publicador: California Institute of Technology
Tipo: Report or Paper; PeerReviewed Formato: application/pdf
Relevância na Pesquisa
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A study is made of the accuracy of electronic digital computer calculations of ground displacement and response spectra from strong-motion earthquake accelerograms. This involves an investigation of methods of the preparatory reduction of accelerograms into a form useful for the digital computations and of the accuracy of subsequent digital calculations. Various checks are made for both the ground displacement and response spectra results, and it is concluded that the main errors are those involved in digitizing the original record. Differences resulting from various investigators digitizing the same experimental record may become as large as 100% of the maximum computed ground displacements. The spread of the results of ground displacement calculations is greater than that of the response spectra calculations. Standardized methods of adjustment and calculation are recommended, to minimize such errors. Studies are made of the spread of response spectral values about their mean. The distribution is investigated experimentally by Monte Carlo techniques using an electric analog system with white noise excitation, and histograms are presented indicating the dependence of the distribution on the damping and period of the structure. Approximate distributions are obtained analytically by confirming and extending existing results with accurate digital computer calculations. A comparison of the experimental and analytical approaches indicates good agreement for low damping values where the approximations are valid. A family of distribution curves to be used in conjunction with existing average spectra is presented. The combination of analog and digital computations used with Monte Carlo techniques is a promising approach to the statistical problems of earthquake engineering. Methods of analysis of very small earthquake ground motion records obtained simultaneously at different sites are discussed. The advantages of Fourier spectrum analysis for certain types of studies and methods of calculation of Fourier spectra are presented. The digitizing and analysis of several earthquake records is described and checks are made of the dependence of results on digitizing procedure...

## If Selma Were Heaven: Economic Transformation and Black Freedom Struggles in the Alabama Black Belt, 1901 - 2000

Forner, Karlyn
Tipo: Dissertação
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In Selma, Alabama in 1965, local African Americans partnered with civil rights organizations to stage a movement for voting rights. The beating of peaceful black marchers by white state troopers on the Edmund Pettus Bridge that March catapulted the city and black demands for the ballot into the national spotlight. When the Voting Rights Act of 1965 was passed five months later, it cemented Selma as a symbol of voting rights. Since then, Selma has become a triumphal moment in the grand narrative of American democracy and citizenship. However, the years after the voting rights movement failed to bring economic opportunities and justice for black citizens in Selma. At the end of the twentieth century, numbing unemployment, gutted houses, and government transfer payments attested to barriers left unbroken by the passage of the 1965 Voting Rights Act. How, then, did Selma become the site of a nationally-geared campaign for voting rights, and why was the right to vote not enough to bring economic justice for African Americans?

This dissertation is a local study that spans the course of century, one that looks at Selma and Dallas County as a place with a long history shaped by white supremacy and agricultural transformation, as well as local relationships and national developments. It begins in 1901...

## Internações sensíveis na atenção primária como indicador de avaliação da Estratégia Saúde da Família; Internaciones sensibles en la atención primaria como indicador de evaluación de la Estrategia Salud de la Familia; Hospitalizations sensitive to primary care as an evaluation indicator for the Family Health Strategy

Fernandes, Viviane Braga Lima; Caldeira, Antônio Prates; Faria, Anderson Antônio de; Rodrigues Neto, João Felício
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf; application/pdf
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## Acilaçúcares presentes em folíolos de tomateiro conferem resistência à traça do tomateiro, Tuta absoluta Meyr; Acylsugars in tomato leaflets confer resistance to the South American tomato pinworm, Tuta absoluta Meyr

Resende, Juliano Tadeu Vilela de; Maluf, Wilson Roberto; Faria, Marcos Ventura; Pfann, Alessandra Zawadzki; Nascimento, Ildon Rodrigues do
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
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Os acilaçúcares presentes no acesso 'LA716' de Lycopersicon pennellii exercem um papel importante na resistência a Tuta absoluta. Foi avaliada a associação entre níveis de resistência à T. absoluta e o nível de acilaçúcares em plantas das gerações F2 e F2RC1 do cruzamento interespecífico L. esculentum 'TOM-584' ;´; L. pennellii 'LA-716'. Na população F2 foram selecionados 4 genótipos com alto teor de acilaçúcares e um com baixo teor. Esses genótipos seleccionados, juntamente com as linhagens parentais e as testemunhas TOM-600 (linhagem com alto teor de 2-tridecanona e resistente a T. absoluta) e TOM-556 (linhagem com baixo teor de acilaçúcares) foram submetidos à infestação natural da traça no campo e avaliados quanto a danos na planta, lesões nos folíolos e porcentagem de folíolos atacados. Na população F2RC1 [=(Lycopersicon esculentum 'TOM-584' ;´; F2)] foram selecionados 4 genótipos com altos teores de acilaçúcares nos folíolos e dois genótipos com baixos teores. Esses genótipos, juntamente com as linhagens parentais e as testemunhas, foram submetidos à infestação em gaiolas, em casa de vegetação. Avaliou-se a ovoposição da traça, os danos na planta e lesões1nos folíolos. Os genótipos F2 BPX-370Bpl#25...

## Genetic progress after cycles of upland rice recurrent selection

Morais Júnior, Odilon Peixoto de; Melo, Patrícia Guimarães Santos; Morais, Orlando Peixoto de; Castro, Adriano Pereira de; Breseghello, Flávio; Utumi, Marley Marico; Pereira, José Almeida; Wruck, Flávio Jesus; Colombari Filho, José Manoel
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
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Periodic assessment of the genetic progress made in recurrent selection programs is essential for assessing the evolution of the programs and identifying the main factors that have contributed to this progress. This study aimed to estimate genetic progress in grain yield, plant height and days-to-flowering achieved in the CNA6 population of upland rice (Oryza sativa L.), after four cycles of recurrent selection; and evaluate the genetic potential of this population to generate superior inbred lines after each selection cycle. The experimental data were obtained from progeny yield trials of each recurrent selection cycle. These trials were carried out in two or three locations per cycle, and consisted of S0:2 progenies and at least three checks. Federer’s augmented block design, with one replication on location (the environment), was adopted. Results revealed genetic progress for grain yield and plant height, with total genetic gains of 375.87 kg ha−1 and -3.90 cm, respectively, during the four selection cycles. The annual relative gain observed for grain yield was 1.54 %. The genetic potential of the population was analysed by the expected proportion of superior inbred lines. The standard adopted as the limit for obtaining superior inbred lines was the average of the checks for each trait. The genetic potential for grain yield and plant height increased during the study period. For days-to-flowering...

## Do we trust the data?: on the validity and reliability of cross-national environmental surveys

Neumayer, Eric
Fonte: Blackwell Publishing on behalf of the Southwestern Social Science Association Publicador: Blackwell Publishing on behalf of the Southwestern Social Science Association
Tipo: Article; PeerReviewed Formato: application/pdf
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This article provides evidence on the validity and reliability of cross-national environmental surveys, an aspect that has not found much attention so far. Methods. Validity can be checked in examining whether cross-national differences in environmental attitudes are in accordance with theoretical hypotheses. For example, a study can claim some validity if concern about inadequate sanitation is strongly negatively correlated with the actual extent of access to sanitation in a country. Results. Several validity checks were undertaken for the Gallup, Gallup, and Dunlap (1993) survey, all of which tend to support its validity. Next, the reliability of cross-national environmental surveys was checked. Both Pearson and Spearman rank correlations were run for similar questions from differing studies. Most correlations were low and statistically insignificant, however, thus putting some doubt on the reliability of cross-national environmental surveys, at least with respect to the questions examined. Conclusions. The findings support the validity of cross-national environmental surveys, but not their reliability. Future surveys should be designed such that validity and reliability checks become easier to undertake.

## The limits of delegation : veto players, central bank independence, and the credibility of monetary policy

Stasavage, David; Keefer, Philip
Fonte: London School of Economics and Political Science Research Publicador: London School of Economics and Political Science Research
Tipo: Article; PeerReviewed Formato: application/pdf
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Governments unable to make credible promises hinder economic development and effective policy making. Scholars have focused considerable attention on checks and balances and the delegation of authority to independent agencies as institutional solutions to this problem. The political conditions under which these institutions enhance credibility, rather than policy stability, are still unclear, however. We show that checks – multiple veto players – enhance credibility, depending on the extent of uncertainty about the location of the status quo, on how agenda control is allocated among the veto players, and on whether veto players have delegated policy making authority to independent agencies. In the context of monetary policy and independent central banks, we find evidence supporting the following predictions: delegation is more likely to enhance credibility and political replacements of central bank governors are less likely in the presence of multiple political veto players; this effect increases with the polarization of veto players.

## Private investment and political institutions

Stasavage, David
Fonte: London School of Economics and Political Science Research Publicador: London School of Economics and Political Science Research
Tipo: Article; PeerReviewed Formato: application/pdf