8,376 research outputs found
Transhumanism and human enhancement: A postmortem
Fil: Vaccari, Andrés. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - Patagonia Norte; Argentina. Macquarie University; Australia. Universidad Nacional de RÃo Negro. Sede Andina. Centro de Estudios en Ciencia, TecnologÃa, Cultura y Desarrollo; Argentin
GAIA Galaxy Survey: a multi-colour galaxy survey with GAIA
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 and to provide multi-colour and multi-epoch broad-band photometry of
these with an end-of-mission angular resolution of 0.35 \as and a
photometric accuracy of 0.2 {mag/arcsec} at
{mag/arcsec}. 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
Earthquake scenarios and seismic input for cultural heritage: applications to the cities of Rome and Florence
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>
We model the Ly luminosity function to estimate the
number of lensed high Ly emitters that may be detected by the
Euclid Deep Survey. To span the whole range of possible predictions we exploit
two Ly luminosity function models and two strong gravitational lensing
models from the literature. We show that the planned Euclid Deep Survey
observing 40 deg over the 920-1850 nm wavelength range down to a flux limit
of erg scm will enable us to find
between and deg lensed Ly emitters at depending on the adopted Ly luminosity function and strong
gravitational lensing model. The obvious [OII], [OIII] and H
contaminants of the Ly 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 H emitters. By combining
Euclid and the SKA, we will thus be able to identify, for the first time, a
sample of to lensed Ly emitters at .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
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
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 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 random variables and a conjecture about the relation of the
values in the two games is formulated.Comment: 20page
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