7,933 research outputs found

    Word Up! Directed motor action improves word learning [Abstract]

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    Can simple motor actions help people expand their vocabulary? Here we show that word learning depends on where students place their flash cards after studying them. In Experiment 1, participants learned the definitions of ”alien words” with positive or negative emotional valence. After studying each card, they placed it in one of two boxes (top or bottom), according to its valence. Participants who were instructed to place positive cards in the top box, consistent with Good is Up metaphors, scored about 10

    The Brauer-Manin Obstruction and Sha[2].

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    We discuss the Brauer-Manin obstruction on del Pezzo surfaces of degree 4. We outline a detailed algorithm for computing the obstruction and provide associated programs in magma. This is illustrated with the computation of an example with an irreducible cubic factor in the singular locus of the defining pencil of quadrics (in contrast to previous examples, which had at worst quadratic irreducible factors). We exploit the relationship with the Tate-Shafarevich group to give new types of examples of Sha[2], for families of curves of genus 2 of the form y^2 = f(x), where f(x) is a quintic containing an irreducible cubic factor

    Finding a Feasible Solution for a Simple LP Problem using Agents

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    In this paper we will describe a Multi-Agent System which is capable of finding a feasible solution of a specially structured linear programming problem. Emphasis is given to correctness issues and termination detection.multi-agent systems;linear programming

    Complex maps without invariant densities

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    We consider complex polynomials f(z)=zℓ+c1f(z) = z^\ell+c_1 for ℓ∈2N\ell \in 2\N and c1∈Rc_1 \in \R, and find some combinatorial types and values of ℓ\ell such that there is no invariant probability measure equivalent to conformal measure on the Julia set. This holds for particular Fibonacci-like and Feigenbaum combinatorial types when ℓ\ell sufficiently large and also for a class of `long-branched' maps of any critical order.Comment: Typos corrected, minor changes, principally to Section

    On the Lebesgue measure of Li-Yorke pairs for interval maps

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    We investigate the prevalence of Li-Yorke pairs for C2C^2 and C3C^3 multimodal maps ff with non-flat critical points. We show that every measurable scrambled set has zero Lebesgue measure and that all strongly wandering sets have zero Lebesgue measure, as does the set of pairs of asymptotic (but not asymptotically periodic) points. If ff is topologically mixing and has no Cantor attractor, then typical (w.r.t. two-dimensional Lebesgue measure) pairs are Li-Yorke; if additionally ff admits an absolutely continuous invariant probability measure (acip), then typical pairs have a dense orbit for f×ff \times f. These results make use of so-called nice neighborhoods of the critical set of general multimodal maps, and hence uniformly expanding Markov induced maps, the existence of either is proved in this paper as well. For the setting where ff has a Cantor attractor, we present a trichotomy explaining when the set of Li-Yorke pairs and distal pairs have positive two-dimensional Lebesgue measure.Comment: 41 pages, 3 figure

    Natural equilibrium states for multimodal maps

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    This paper is devoted to the study of the thermodynamic formalism for a class of real multimodal maps. This class contains, but it is larger than, Collet-Eckmann. For a map in this class, we prove existence and uniqueness of equilibrium states for the geometric potentials −tlog⁡∣Df∣-t \log|Df|, for the largest possible interval of parameters tt. We also study the regularity and convexity properties of the pressure function, completely characterising the first order phase transitions. Results concerning the existence of absolutely continuous invariant measures with respect to the Lebesgue measure are also obtained

    GAOS: Spatial optimisation of crop and nature within agricultural fields

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    This paper proposes and demonstrates a spatial optimiser that allocates areas of inefficient machine manoeuvring to field margins thus improving the use of available space and supporting map-based Controlled Traffic Farming. A prototype web service (GAOS) allows farmers to optimise tracks within their fields and explore planning alternatives prior to downloading the plans to their RTK GPS-guided steering system. GAOS retrieves accurate data on field geometry from a geo-database. Via a web interface, the farmer sets options regarding operation properties, potential locations for field margins and headlands, etc. Next, an optimisation script that employs an open source geospatial library (osgeo.ogr) is called. The objective function considers costs involved with un-cropped areas, turning at headlands and subsidies received for field margins. Optimisation results are stored in a database and are available for (1) viewing via the web interface, (2) downloading to the GPS-guided steering system and (3) communication to third parties

    Endoscopic Camera Control by Head Movements for Thoracic Surgery

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    In current video-assisted thoracic surgery, the endoscopic camera is operated by an assistant of the surgeon, which has several disadvantages. This paper describes a system which enables the surgeon to control the endoscopic camera without the help of an assistant. The system is controlled using head movements, so the surgeon can use his/her hands to oper- ate the instruments. The system is based on a flexible endoscope, which leaves more space for the surgeon to operate his/her instruments compared to a rigid endoscope. The endoscopic image is shown either on a monitor or by means of a head- mounted display. Several trial sessions were performed with an anatomical model. Results indicate that the developed concept may provide a solution to some of the problems currently encountered in video-assisted thoracic surgery. The use of a head-mounted display turned out to be a valuable addition since it ensures the image is always in front of the surgeon’s eyes

    Volatile aldehydes in libraries and archives

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    Volatile aldehydes are produced during degradation of paper-based materials. This may result in their accumulation in archival and library repositories. However, no systematic study has been performed so far. In the frame of this study, passive sampling was carried out at ten locations in four libraries and archives. Despite the very variable sampling locations, no major differences were found, although air-filtered repositories were found to have lower concentrations while a non-ventilated newspaper repository exhibited the highest concentrations of volatile aldehydes (formaldehyde, acetaldehyde, furfural and hexanal). Five employees in one institution were also provided with personal passive samplers to investigate employees’ exposure to volatile aldehydes. All values were lower than the presently valid exposure limits. The concentration of volatile aldehydes, acetic acid, and volatile organic compounds (VOCs) in general was also compared with that of outdoor-generated pollutants. It was evident that inside the repository and particularly inside archival boxes, the concentration of VOCs and acetic acid was much higher than the concentration of outdoor-generated pollutants, which are otherwise more routinely studied in connection with heritage materials. This indicates that further work on the pro-degradative effect of VOCs on heritage materials is necessary and that monitoring of VOCs in heritage institutions should become more widespread
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