870 resultados para Regular tessellations
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A family of quadratic programming problems whose optimal values are upper bounds on the independence number of a graph is introduced. Among this family, the quadratic programming problem which gives the best upper bound is identified. Also the proof that the upper bound introduced by Hoffman and Lovász for regular graphs is a particular case of this family is given. In addition, some new results characterizing the class of graphs for which the independence number attains the optimal value of the above best upper bound are given. Finally a polynomial-time algorithm for approximating the size of the maximum independent set of an arbitrary graph is described and the computational experiments carried out on 36 DIMACS clique benchmark instances are reported.
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Let G be a finite graph with an eigenvalue μ of multiplicity m. A set X of m vertices in G is called a star set for μ in G if μ is not an eigenvalue of the star complement G\X which is the subgraph of G induced by vertices not in X. A vertex subset of a graph is (k ,t)-regular if it induces a k -regular subgraph and every vertex not in the subset has t neighbors in it. We investigate the graphs having a (k,t)-regular set which induces a star complement for some eigenvalue. A survey of known results is provided and new properties for these graphs are deduced. Several particular graphs where these properties stand out are presented as examples.
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In spectral graph theory a graph with least eigenvalue 2 is exceptional if it is connected, has least eigenvalue greater than or equal to 2, and it is not a generalized line graph. A ðk; tÞ-regular set S of a graph is a vertex subset, inducing a k-regular subgraph such that every vertex not in S has t neighbors in S. We present a recursive construction of all regular exceptional graphs as successive extensions by regular sets.
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In this paper, relevant results about the determination of (k,t)-regular sets, using the main eigenvalues of a graph, are reviewed and some results about the determination of (0,2)-regular sets are introduced. An algorithm for that purpose is also described. As an illustration, this algorithm is applied to the determination of maximum matchings in arbitrary graphs.
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Rationale Electronic cigarettes are becoming increasingly popular among smokers worldwide. Commonly reported reasons for use include the following: to quit smoking, to avoid relapse, to reduce urge to smoke, or as a perceived lower-risk alternative to smoking. Few studies, however, have explored whether electronic cigarettes (e-cigarettes) deliver measurable levels of nicotine to the blood. Objective This study aims to explore in experienced users the effect of using an 18-mg/ml nicotine first-generation e-cigarette on blood nicotine, tobacco withdrawal symptoms, and urge to smoke. Methods Fourteen regular e-cigarette users (three females), who are abstinent from smoking and e-cigarette use for 12 h, each completed a 2.5 h testing session. Blood was sampled, and questionnaires were completed (tobacco-related withdrawal symptoms, urge to smoke, positive and negative subjective effects) at four stages: baseline, 10 puffs, 60 min of ad lib use and a 60-min rest period. Results Complete sets of blood were obtained from seven participants. Plasma nicotine concentration rose significantly from a mean of 0.74 ng/ml at baseline to 6.77 ng/ml 10 min after 10 puffs, reaching a mean maximum of 13.91 ng/ml by the end of the ad lib puffing period. Tobacco-related withdrawal symptoms and urge to smoke were significantly reduced; direct positive effects were strongly endorsed, and there was very low reporting of adverse effects. Conclusions These findings demonstrate reliable blood nicotine delivery after the acute use of this brand/model of e-cigarette in a sample of regular users. Future studies might usefully quantify nicotine delivery in relation to inhalation technique and the relationship with successful smoking cessation/harm reduction.
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Dissertação de Mestrado, Educação Especial – Domínio Cognitivo e Motor, Escola Superior de Educação e Comunicação, Universidade do Algarve, 2015
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Dissertação de mestrado, Educação Especial - Domínios Cognitivo e Motor, Escola Superior de Educação e Comunicação, Universidade do Algarve, 2015
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Governor Moses calls on South Carolinians to endeavor to become a respected member of the United States following the U.S. Civil War. His message addresses the status of the national debt, South Carolina public education, the South Carolina Orphan Asylum, the South Carolina Lunatic Asylum, the state penitentiary, the state’s quarantine of small pox, the revenue-generating phosphate deposits in the state, immigration to the state, the state’s flagship university, current state legislation, and the state militia.
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This speech was delivered to by the Governor to give the general assembly information of the condition of the state and give them recommendations to consider measures that the Governor deems necessary or expedient. He provides the information regarding the state debt, taxes, and bonded debt. He describes the financial agent of the state as well as the expenditures of the state government.
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Research and practice regarding LO students usually has focussed upon defining and supplementing deficiencies rather than seeking unique talents and capability patterns for learning and expression. This study examined nine dimensions that may constitute artistic or creative talent and compared LDs with "regular-class" students, pair-wise and as groups, for levels and distributions of the dimensions. For 14 LO and 9 "regular-class" elementary-school subjects, both genders, data were taken by direct observation, from a standardized test and assessments by two practicing artists. Assessments by artists were in concord. LOs improved more in "Composition". No other significant class, age or gender-related differences were found.
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Each of the forty Toronto Board of Education behavioural teachers was matched as closely as possible .with a regular cIassroom teacher from the same schooI, 0f the same sex, and teaching approxiately the same age group of chiIdren. A II of these teachers were sent a questionnaire (based on Herzberg's model) whose content reflected various aspects of job satisfaction or dissatisfaction. Demographic data was also gathered to be used in the study for examining correlations between satisfaction and various factors . T 10 additional questions were asked regarding factors that IOU Id influence the i r staying or Ieaving and one question was asked about lIerit pay . Chi Square tests and t-tests were conducted on the results. The majority of each group of teachers was very satisfied with their job while the behavioural teachers were significantly more satisfied than the regular teachers. Intrinsic factors played a more signi ficant role than did extrinsic ones. The demographic factors couId be found to be predictors of job satisfaction or dissatisfaction.
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Tesis (Maestría en Psicología con orientación en Psicología Laboral y Organizacional) UANL, 2013.
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Tesis (Maestría en Psicología con orientación en Psicología Laboral y Organizacional) UANL, 2013.