8,375 research outputs found

    Transhumanism and human enhancement: A postmortem

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    Fil: Vaccari, Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Macquarie University; Australia. Universidad Nacional de Río Negro. Sede Andina. Centro de Estudios en Ciencia, Tecnología, Cultura y Desarrollo; Argentin

    GAIA Galaxy Survey: a multi-colour galaxy survey with GAIA

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    The performance expected from a galaxy survey to be carried out with GAIA, the GAIA Galaxy Survey, is outlined. From a statistical model of galaxy number density, size and surface brightness distribution, and from detailed numerical simulations based on real images, it is conservatively estimated that GAIA would be able to detect and observe about 3 million galaxies brighter than V≃17V \simeq 17 and to provide multi-colour and multi-epoch broad-band photometry of these with an end-of-mission angular resolution of ≃\simeq 0.35 \as and a photometric accuracy of simeqsimeq 0.2 {mag/arcsec2^2} at μV=20\mu_V = 20 {mag/arcsec2^2}. The substantial scientific case for performing such a survey and the additional efforts required in terms of mission preparation, operations and telemetry are also discussed.Comment: 6 pages, 5 figures, to appear in the Proceedings of the Summer School "GAIA: a European Space Project", held on the 13-18 May 2001 at the Ecole de Physique des Houches, Les Houches, France, published in the "Journal de Physique IV", EDP Science

    Artificial Respiration and AHN: Some Similarities and Differences

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    Earthquake scenarios and seismic input for cultural heritage: applications to the cities of Rome and Florence

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    For historical buildings and monuments, i.e. when considering time intervals of about a million year (we do not want to loose cultural heritage), the applicability of standard estimates of seismic hazard is really questionable. A viable alternative is represented by the use of the scenario earthquakes, characterized at least in terms of magnitude, distance and faulting style, and by the treatment of complex source processes. Scenario-based seismic hazard maps are purely based on geophysical and seismotectonic features of a region and take into account the occurrence frequency of earthquakes only for their classification into exceptional (catastrophic), rare (disastrous), sporadic (very strong), occasional (strong) and frequent. Therefore they may provide an upper bound for the ground motion levels to be expected for most regions of the world, more appropriate than probabilities of exceedance in view of the long time scales required for the protection of historical buildings. The neo-deterministic approach naturally supplies realistic time series of ground motion, which represent also reliable estimates of ground displacement readily applicable to seismic isolation techniques, useful to preserve historical monuments and relevant man made structures. This methodology has been successfully applied to many urban areas worldwide for the purpose of seismic microzoning, to strategic buildings, lifelines and cultural heritage sites; we will discuss its application to the cities of Rome and Florence

    Finding bright <i>z</i> ≥ 6.6 Ly <i>α</i> emitters with lensing: prospects for <i>Euclid</i>

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    We model the z≥6.6z \geq 6.6 Lyα\alpha luminosity function to estimate the number of lensed high−z-z Lyα\alpha emitters that may be detected by the Euclid Deep Survey. To span the whole range of possible predictions we exploit two Lyα\alpha luminosity function models and two strong gravitational lensing models from the literature. We show that the planned Euclid Deep Survey observing 40 deg2^2 over the 920-1850 nm wavelength range down to a flux limit of Flim=5×10−17 F_{lim}=5\times10^{-17}\,erg s−1 ^{-1}\,cm−2^{-2} will enable us to find between ∼0.85\sim 0.85 and ∼1.82\sim 1.82 deg−2^{-2} lensed Lyα\alpha emitters at z≥6.6z \geq 6.6 depending on the adopted Lyα\alpha luminosity function and strong gravitational lensing model. The obvious [OII], [OIII] and Hβ\beta contaminants of the Lyα\alpha lensed population will be identified with the help of Euclid's spectral resolving power, while the SKA will enable the identification of the interloper population of Hα\alpha emitters. By combining Euclid and the SKA, we will thus be able to identify, for the first time, a sample of ∼34\sim 34 to ∼73\sim 73 lensed Lyα\alpha emitters at z≥6.6z \geq 6.6.Comment: Accepted for publication in MNRAS on 20 June 2017. (NEW: Amended Latex

    A population of extreme mid-to-near-infrared sources: obscured AGN and dusty starbursts

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    We present a sample of mid-infrared detected sources from the European Large Area ISO Survey (ELAIS) regions characterised by strong mid-IR radiation with faint near-IR and optical counterparts. These extreme mid-to-near-IR objects (EMNOs) are defined here by a flux ratio of f_15um / f_2.2um > 25. This population is not obvious in deeper small area ISO surveys, though it produces more than 20% of the observed cosmic IR background radiation (CIRB) at 15um above 1 mJy. Near-future large area deep mid-IR surveys with the Spitzer Space Telescope, however, are bound to uncover large amounts of these objects, which we argue to most likely be obscured AGN, based on SED shapes and X-ray data. Very strong dusty starbursts at z>1 may also have high mid-to-near-IR flux ratios, but using the MIR/NIR and FIR/MIR ratios these may be separated. Most of our EMNOs appear to be ULIRGs, half are also extremely red objects (ERO). A curious case of a low redshift, less luminous object with a very young stellar population is also found. We predict that the simple broad band selection method makes EMNOs a useful window into high-redshift obscured nuclear activity and its sought after relation to star-formation, in a similar way that EROs have been used to define samples of high-redshift early type galaxies.Comment: 8 pages, 3 figures. A&A accepted version. Results unchanged but discussion is significantly expande

    Variance Allocation and Shapley Value

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    Motivated by the problem of utility allocation in a portfolio under a Markowitz mean-variance choice paradigm, we propose an allocation criterion for the variance of the sum of nn possibly dependent random variables. This criterion, the Shapley value, requires to translate the problem into a cooperative game. The Shapley value has nice properties, but, in general, is computationally demanding. The main result of this paper shows that in our particular case the Shapley value has a very simple form that can be easily computed. The same criterion is used also to allocate the standard deviation of the sum of nn random variables and a conjecture about the relation of the values in the two games is formulated.Comment: 20page
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