35,572 research outputs found

    A redshift survey towards the CMB Cold Spot

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    We have carried out a redshift survey using the VIMOS spectrograph on the VLT towards the Cosmic Microwave Background cold spot. A possible cause of the cold spot is the Integrated Sachs-Wolfe effect imprinted by an extremely large void (hundreds of Mpc in linear dimension) at intermediate or low redshifts. The redshift distribution of over seven hundred z<1 emission-line galaxies drawn from an I-band flux limited sample of galaxies in the direction of the cold spot shows no evidence of a gap on scales of Delta-z> 0.05 as would be expected if such a void existed at 0.35<z<1. There are troughs in the redshift distribution on smaller scales (Delta-z ~0.01) indicating that smaller scale voids may connect regions separated by several degrees towards the cold spot. A comparison of this distribution with that generated from similarly-sized subsamples drawn from widely-spaced pointings of the VVDS survey does not indicate that the redshift distribution towards the cold spot is anomalous or that these small gaps can be uniquely attributed to real voids.Comment: MNRAS in press, 6 page

    The 6C** Sample and the Highest Redshift Radio Galaxies

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    We present a new radio sample, 6C** designed to find radio galaxies at z > 4 and discuss some of its near-infrared imaging follow-up results.Comment: 2 pages, 2 figures, to appear in proceedings of 'Multi-wavelength AGN surveys', Cozumel, 200

    The golden ratio in Schwarzschild-Kottler black holes

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    In this paper we show that the golden ratio is present in the Schwarzschild-Kottler metric. For null geodesics with maximal radial acceleration, the turning points of the orbits are in the golden ratio Ω=(5−1)/2\Phi = (\sqrt{5}-1)/2. This is a general result which is independent of the value and sign of the cosmological constant Λ\Lambda

    Service scheduling in garden maintenance

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    Neoturf is a Portuguese company working in the area of project, building and garden’s maintenance. Neoturf would like to have a procedure for scheduling and routing efficiently the clients from garden maintenance services. The company has two teams available during the whole year and an additional team during summer to handle all the maintenance jobs. Each team consists of two or three employees with a vehicle fully equipped with the tools that allow to carry out every kind of maintenance service. In the beginning of each year, the number and frequency of maintenance interventions to conduct during the year, on each client, are accorded. Each client is assigned to the same team and, usually, time windows are established so that visits to the client should occur only within these periods. As the Neoturf costumers’ are geographically spread over a wide region, the total distance on visiting clients is a factor that has a heavy weight on the costs of the company. Neoturf is concerned with reducing these costs, while satisfying the agreements with the clients

    Behaviour of traditional Portuguese timber roof structures

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    The aim of this paper is to present the results of a structural analysis of common trusses traditionally used in roof construction in Portugal. The study includes the results of a preliminary survey intending to assess the geometry, materials and on site pathologies, as well as a twodimensional linear elastic static and dynamic analysis. The trusses behaviour under symmetric and non-symmetric loads, the king post/tie-beam connection, the stiffness of the joints and the incorrect positioning of the purlins, were some of the structural aspects that have been investigated

    Dactylorhiza elata, Stately Dactylorhiza

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    Mediterranean regional assessment: Near Threatened (NT) The species is found from southwestern Europe and northwestern Africa. In two countries within the Mediterranean distribution (France and Portugal) populations or habitat of this species have declined by more than 30% over three generations. In another two countries (Algeria and Morocco) a similar decline is suspected but cannot yet be confirmed, and in Spain populations appear to be relatively abundant however there is no information on population trends. Elsewhere the species is known only from singlesites in Sardinia and Tunisia. whilst the extent of occurrence is very large, the area of occupancy (AOO) is possibly restricted however distribution data are inadequate to confirm the AOO. Therefore whilst the rate of decline cannot be measured throughout the range of the species, the Mediterranean population decline is confirmed, it is ongoing and is not reversible, consequently this species is close to classification as Vulnerable (A2c and A4c). Further to this, if monitoring data become available to provide an indication of population trends in Spain and these show that it is in decline then it is clear that the species should be considered threatened at both the Mediterranean and global scales. This species is therefore classed as Near Threatened, approaching Vulnerable (A2c+4c)

    Modelling of timber joints in traditional structures

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    Original unstrengthened timber connections and the effects of different strengthening techniques have been evaluated experimentally with tests on full-scale birdsmouth joints. Experimental results show that structural response of traditional timber connections under cyclic loading cannot be represented by common constraint models, like perfect hinges or rigid joints, but should be using semi-rigid and friction based models. A research program has investigated the behaviour of old timber joints and examined strengthening criteria. The main parameters affecting the mechanical behaviour of the connection have been singled out. A synthetic model of cyclic behaviour has been adapted on the basis of experimental results
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