1,905 research outputs found

    Homogeneity analysis with k sets of variables: An alternating least squares method with optimal scaling features

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    Homogeneity analysis, or multiple correspondence analysis, is usually applied to k separate variables. In this paper, it is applied to sets of variables by using sums within sets. The resulting technique is referred to as OVERALS. It uses the notion of optimal scaling, with transformations that can be multiple or single. The single transformations consist of three types: (1) nominal; (2) ordinal; and (3) numerical. The corresponding OVERALS computer program minimizes a least squares loss function by using an alternating least squares algorithm. Many existing linear and non-linear multivariate analysis techniques are shown to be special cases of OVERALS. Disadvantages of the OVERALS method include the possibility of local minima in some complicated special cases, a lack of information on the stability of results, and its inability to handle incomplete data matrices. Means of dealing with some of these problems are suggested (i.e., an alternating least squares algorithm to solve the minimization problem). An application of the method to data from an epidemiological survey is provided

    All the world's a screen.

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    Charlotte Gould and Paul Sermon developed and presented this collaborative new artwork entitled 'All the World's a Screen', a live interactive telecommunications performance, to link public audiences in Manchester and Barcelona. On the evening of Saturday 28th May 2011 participants at MadLab in Manchester's Northern Quarter and Hangar Artist Studios in Poblenou, Barcelona were joined together on screen for the first time to create their very own interactive generative cinema experience, complete with sets, costumes and props. Employing the scenography techniques of Alfred Hitchcock the artists created a miniature film set in which the remote audiences acted and directed their own movie, transporting participants into animated environments and sets where they created unique personalised narratives

    Interaction Effects on Number Fluctuations in a Bose-Einstein Condensate of Light

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    We investigate the effect of interactions on condensate-number fluctuations in Bose-Einstein condensates. For a contact interaction we variationally obtain the equilibrium probability distribution for the number of particles in the condensate. To facilitate comparison with experiment, we also calculate the zero-time delay autocorrelation function g(2)(0)g^{(2)}(0) for different strengths of the interaction. Finally, we focus on the case of a condensate of photons and discuss possible mechanisms for the interaction.Comment: 13 pages, version 3, 4 figure

    Phase diffusion in a Bose-Einstein condensate of light

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    We study phase diffusion in a Bose-Einstein condensate of light in a dye-filled optical microcavity, i.e., the spreading of the probability distribution for the condensate phase. To observe this phenomenon, we propose an interference experiment between the condensed photons and an external laser. We determine the average interference patterns, considering quantum and thermal fluctuations as well as dissipative effects due to the dye. Moreover, we show that a representative outcome of individual measurements can be obtained from a stochastic equation for the global phase of the condensate

    Theory for Bose-Einstein condensation of light in nano-fabricated semiconductor microcavities

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    We construct a theory for Bose-Einstein condensation of light in nano-fabricated semiconductor microcavities. We model the semiconductor by one conduction and one valence band which consist of electrons and holes that interact via a Coulomb interaction. Moreover, we incorporate screening effects by using a contact interaction with the scattering length for a Yukawa potential and describe in this manner the crossover from exciton gas to electron-hole plasma as we increase the excitation level of the semiconductor. We then show that the dynamics of the light in the microcavities is damped due to the coupling to the semiconductor. Furthermore, we demonstrate that on the electron-hole plasma side of the crossover, which is relevant for the Bose-Einstein condensation of light, this damping can be described by a single dimensionless damping parameter that depends on the external pumping. Hereafter, we propose to probe the superfluidity of light in these nano-fabricated semiconductor microcavities by making use of the differences in the response in the normal or superfluid phase to a sudden rotation of the trap. In particular, we determine frequencies and damping of the scissors modes that are excited in this manner. Moreover, we show that a distinct signature of the dynamical Casimir effect can be observed in the density-density correlations of the excited light fluid

    Modeling match performance in elite volleyball players: importance of jump load and strength training characteristics

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    In this study, we investigated the relationships between training load, perceived wellness and match performance in professional volleyball by applying the machine learning techniques XGBoost, random forest regression and subgroup discovery. Physical load data were obtained by manually logging all physical activities and using wearable sensors. Daily wellness of players was monitored using questionnaires. Match performance was derived from annotated actions by a video scout during matches. We identified conditions of predictor variables that related to attack and pass performance (p < 0.05). Better attack performance is related to heavy weights of lower-body strength training exercises in the preceding four weeks. However, worse attack performance is linked to large variations in weights of full-body strength training exercises, excessively heavy upper-body strength training, low jump heights and small variations in the number of high jumps in the four weeks prior to competition. Lower passing performance was associated with small variations in the number of high jumps in the preceding week and an excessive amount of high jumps performed, on average, in the two weeks prior to competition. Differences in findings with respect to passing and attack performance suggest that elite volleyball players can improve their performance if training schedules are adapted to the position of a player.Algorithms and the Foundations of Software technolog

    Oxidatively drying coating composition

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    coating composition comprising an oxidatively drying coating binder and a chelate comprising at least one group according to the following formula (I): forming a complex with a metal ion, A1 and A2 both being an aromatic residue, R1 and R3 being covalently bonded groups, and R2 being a divalent organic radical, wherein at least one solubilizing group is coivalently bonded to the chelating compound. The solubilizing group is a non-polar group, preferable an aliphatic group having at least four carbon atoms, covalently bonded to A1 and/or A2. The metal ion is a divalent ion of a metal selected from the group of manganese, cobalt, copper, lead, zirconium, iron, lanthanium, cerium, vanadium, and clacium or a trivalent ion of a metal selected from the group of manganese, cobalt, lead, zirconium, iron, lanthanium, cerium, and vanadium, combined with a monovalent counterion

    The Long-Term Evolution of Social Organization

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    This chapter outlines how the ‘innovation innovation’ transformed the world of our distant ancestors into that in which we live today. It focuses on the relationship between people and the material world, as it is the material world that has been most drastically, and measurably, transformed over the last several tens of thousands of years. In view of what we know about such distant periods, and in view of the space allot-ted to us here, it will not surprise the reader that we do so in the form of a narrative that is only partly underpinned by substantive data. We emphasize this because we do not want to hide from the reader the speculative nature of the story that follows. Yet we firmly believe that, in very general terms, this scenario is correct, and that further research will vindicate us.We first give examples of the kinds of abstractions, and the hierarchy of conceptual dimensions necessary for prehistoric human beings and their ancestors, to conquer matter, i.e. to conceptually understand, transmit and apply the operations needed to master the making of a range of objects made out of stone, bone, wood, clay and other materials. Some of the abstractions that had to be conceived in this domain re-semble those that Read et al. (http://www.escholarship.org/uc/item/2798j162) refer to, while others apply to this domain alone, and had to be truly ‘invented’. It is then argued that such ‘identification of conceptual dimensions’ is a process that underlies all human activity, and we look a little closer at how that process relates to invention and innovation.Lastly, we shift our attention to the role of innovation, information processing and communication in the emergence of social institutions, and in the structural transformation of human societies as they grow in size and complexity. In particular, we look at the role that problem solving and invention play in creating more and more complex societies, encompassing increasing numbers of people, more and more diverse institutions, and an – ultimately seemingly all-encompassing – appropriation of the natural environment. To illustrate this development we will focus on the origins and growth of urban systems

    Standard survey methods for estimating colony losses and explanatory risk factors in Apis mellifera

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    This chapter addresses survey methodology and questionnaire design for the collection of data pertaining to estimation of honey bee colony loss rates and identification of risk factors for colony loss. Sources of error in surveys are described. Advantages and disadvantages of different random and non-random sampling strategies and different modes of data collection are presented to enable the researcher to make an informed choice. We discuss survey and questionnaire methodology in some detail, for the purpose of raising awareness of issues to be considered during the survey design stage in order to minimise error and bias in the results. Aspects of survey design are illustrated using surveys in Scotland. Part of a standardized questionnaire is given as a further example, developed by the COLOSS working group for Monitoring and Diagnosis. Approaches to data analysis are described, focussing on estimation of loss rates. Dutch monitoring data from 2012 were used for an example of a statistical analysis with the public domain R software. We demonstrate the estimation of the overall proportion of losses and corresponding confidence interval using a quasi-binomial model to account for extra-binomial variation. We also illustrate generalized linear model fitting when incorporating a single risk factor, and derivation of relevant confidence intervals
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