200 research outputs found

    Evolutionary Approaches to Optimization Problems in Chimera Topologies

    Full text link
    Chimera graphs define the topology of one of the first commercially available quantum computers. A variety of optimization problems have been mapped to this topology to evaluate the behavior of quantum enhanced optimization heuristics in relation to other optimizers, being able to efficiently solve problems classically to use them as benchmarks for quantum machines. In this paper we investigate for the first time the use of Evolutionary Algorithms (EAs) on Ising spin glass instances defined on the Chimera topology. Three genetic algorithms (GAs) and three estimation of distribution algorithms (EDAs) are evaluated over 10001000 hard instances of the Ising spin glass constructed from Sidon sets. We focus on determining whether the information about the topology of the graph can be used to improve the results of EAs and on identifying the characteristics of the Ising instances that influence the success rate of GAs and EDAs.Comment: 8 pages, 5 figures, 3 table

    Low and intermediate energy electron collisions with the C2_2^- molecular anion

    Full text link
    Calculations are presented which use the molecular R-matrix with pseudo-states (MRMPS) method to treat electron impact electron detachment and electronic excitation of the carbon dimer anion. Resonances are found above the ionisation threshold of C2_2^- with 1Σg+^1\Sigma^+_g, 1Πg^1\Pi_g and 3Πg^3\Pi_g symmetry. These are shape resonances trapped by the effect of an attractive polarisation potential competing with a repulsive Coulomb interaction. The Πg\Pi_g resonances are found to give structure in the detachment cross section similar to that observed experimentally. Both excitation and detachment cross sections are found to be dominated by large impact parameter collisions whose contribution is modelled using the Born approximation.Comment: 18 pages, 5 figures constructed from 8 file

    Multiple scattering approach to elastic electron collisions with molecular clusters

    Get PDF
    We revisit our multiple-scattering method to treat low energy elastic electron collisions with (H2O)2. Calculations are performed for different geometries of the water dimer with different dipole moments. The effect of the dipole moment of the cluster is analysed. The elastic cross sections are compared to R-matrix results. Good agreement is found above 1 eV for all geometries. Results conrm the validity of the technique

    Revista de Vertebrados de la Estación Biológica de Doñana

    Get PDF
    Dimorfismo sexual en Microtus cabrerae en base a los caracteres de su pelvis.Notas sobre la distribución y ecología de Microtus cabreae, Thomas, 1906.Alimentación de la culebra bastarda (Malpolon monspessulanus, Ophidia, Colubridae) en el S. O. de España.Selectividad en la predación de la lechuza común (Tyto alba) sobre Rano ridibunda.Variations in the food habits of the european Eagle Owl. (Bubo bubo)Contaminación en huevos de aves silvestres de lSuroeste de España por residuos organoclorados (Insecticidas y bifenilos policlorados)Sobre el status taxonómico del águila imperial ibéricaEstudio filogenético y comparativo de Microtus cabrerae y Microtus brecciensisDescripción de una nueva especie de liebre (Lepus castroviejoi), endémica de la Cordillera CantábricaPeer reviewe

    Modelling the underlying principles of human aesthetic preference in evolutionary art

    Get PDF
    Our understanding of creativity is limited, yet there is substantial research trying to mimic human creativity in artificial systems and in particular to produce systems that automatically evolve art appreciated by humans. We propose here to study human visual preference through observation of nearly 500 user sessions with a simple evolutionary art system. The progress of a set of aesthetic measures throughout each interactive user session is monitored and subsequently mimicked by automatic evolution in an attempt to produce an image to the liking of the human user

    Potential of a multiparametric optical sensor for determining in situ the maturity components of red and white vitis vinifera wine grapes

    Get PDF
    A non-destructive fluorescence-based technique for evaluating Vitis vinifera L. grape maturity using a portable sensor (Multiplex ®) is presented. It provides indices of anthocyanins and chlorophyll in Cabernet Sauvignon, Merlot and Sangiovese red grapes and of flavonols and chlorophyll in Vermentino white grapes. The good exponential relationship between the anthocyanin index and the actual anthocyanin content determined by wet chemistry was used to estimate grape anthocyanins from in field sensor data during ripening. Marked differences were found in the kinetics and the amount of anthocyanins between cultivars and between seasons. A sensor-driven mapping of the anthocyanin content in the grapes, expressed as g/kg fresh weight, was performed on a 7-ha vineyard planted with Sangiovese. In the Vermentino, the flavonol index was favorably correlated to the actual content of berry skin flavonols determined by means of HPLC analysis of skin extracts. It was used to make a non-destructive estimate of the evolution in the flavonol concentration in grape berry samplings. The chlorophyll index was inversely correlated in linear manner to the total soluble solids (°Brix): it could, therefore, be used as a new index of technological maturity. The fluorescence sensor (Multiplex) possesses a high potential for representing an important innovative tool for controlling grape maturity in precision viticulture

    Revista de Vertebrados de la Estación Biológica de Doñana

    Get PDF
    Descripción de una nueva subespecie de lagarto ágil (Lacerta agilis garzoni) de los PirineosDiet of the Montagu's Harrier (Circus pygargus) in southwestern Spain SpainObservaciones ornitológicas en la Guayana francesaDaily feeding rhythm of ducks on the marismas of the Guadalquivir and their responses to birds of preyA note on the emetic technique for obtaining food samples from passerine birds.Distribución de contaminantes organoclorados en tejidos de garza imperial (Ardea purpurea) y pato cuchara (Anas clypeata) de la Reserva Biológica de Doñana.Etograma cuantificado del gamo (Dama dama) en libertad.Peer reviewe

    Changes in smoking prevalence among U.S. adults by state and region: Estimates from the Tobacco Use Supplement to the Current Population Survey, 1992-2007

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Tobacco control policies at the state level have been a critical impetus for reduction in smoking prevalence. We examine the association between recent changes in smoking prevalence and state-specific tobacco control policies and activities in the entire U.S.</p> <p>Methods</p> <p>We analyzed the 1992-93, 1998-99, and 2006-07 Tobacco Use Supplement to the Current Population Survey (TUS-CPS) by state and two indices of state tobacco control policies or activities [initial outcome index (IOI) and the strength of tobacco control (SOTC) index] measured in 1998-1999. The IOI reflects cigarette excise taxes and indoor air legislation, whereas the SOTC reflects tobacco control program resources and capacity. Pearson Correlation coefficient between the proportionate change in smoking prevalence from 1992-93 to 2006-07 and indices of tobacco control activities or programs was the main outcome measure.</p> <p>Results</p> <p>Smoking prevalence decreased from 1992-93 to 2006-07 in both men and women in all states except Wyoming, where no reduction was observed among men, and only a 6.9% relative reduction among women. The percentage reductions in smoking in men and women respectively were the largest in the West (average decrease of 28.5% and 33.3%) and the smallest in the Midwest (18.6% and 20.3%), although there were notable exceptions to this pattern. The decline in smoking prevalence by state was correlated with the state's IOI in both women and men (r = -0.49, p < 0.001; r = -0.31, p = 0.03; respectively) and with state's SOTC index in women(r = -0.30, p = 0.03 0), but not men (r = -0.21, p = 0.14).</p> <p>Conclusion</p> <p>State level policies on cigarette excise taxes and indoor air legislation correlate strongly with reductions in smoking prevalence since 1992. Strengthening and systematically implementing these policies could greatly accelerate further reductions in smoking.</p
    corecore