383 research outputs found
Undecidability as solution to the problem of measurement: fundamental criterion for the production of events
In recent papers we put forth a new interpretation of quantum mechanics,
colloquially known as ``the Montevideo interpretation''. This interpretation is
based on taking into account fundamental limits that gravity imposes on the
measurement process. As a consequence one has that situations develop where a
reduction process is undecidable from an evolution operator. When such a
situation is achieved, an event has taken place. In this paper we sharpen the
definition of when and how events occur, more precisely we give sufficient
conditions for the occurrence of events. We probe the new definition in an
example. In particular we show that the concept of undecidability used is not
``FAPP'' (for all practical purposes), but fundamental.Comment: 10 pages, contributed to the Castagnino Festschrif
Computing option pricing models under transaction costs
AbstractThis paper deals with the Barles–Soner model arising in the hedging of portfolios for option pricing with transaction costs. This model is based on a correction volatility function Ψ solution of a nonlinear ordinary differential equation. In this paper we obtain relevant properties of the function Ψ which are crucial in the numerical analysis and computing of the underlying nonlinear Black–Scholes equation. Consistency and stability of the proposed numerical method are detailed and illustrative examples are given
Quantum Systems Equilibrate Rapidly for Most Observables
Considering any Hamiltonian, any initial state, and measurements with a small
number of possible outcomes compared to the dimension, we show that most
measurements are already equilibrated. To investigate non-trivial equilibration
we therefore consider a restricted set of measurements. When the initial state
is spread over many energy levels, and we consider the set of observables for
which this state is an eigenstate, most observables are initially out of
equilibrium yet equilibrate rapidly. Moreover, all two-outcome measurements,
where one of the projectors is of low rank, equilibrate rapidly.Comment: Main Text: 5 pages, 1 figure. Appendices: 7 pages, 1 figur
The OTELO survey. A case study of [O III]4959,5007 emitters at <z> = 0.83
The OTELO survey is a very deep, blind exploration of a selected region of
the Extended Groth Strip and is designed for finding emission-line sources
(ELSs). The survey design, observations, data reduction, astrometry, and
photometry, as well as the correlation with ancillary data used to obtain a
final catalogue, including photo-z estimates and a preliminary selection of
ELS, were described in a previous contribution. Here, we aim to determine the
main properties and luminosity function (LF) of the [O III] ELS sample of OTELO
as a scientific demonstration of its capabilities, advantages, and
complementarity with respect to other surveys. The selection and analysis
procedures of ELS candidates obtained using tunable filter (TF) pseudo-spectra
are described. We performed simulations in the parameter space of the survey to
obtain emission-line detection probabilities. Relevant characteristics of [O
III] emitters and the LF([O III]), including the main selection biases and
uncertainties, are presented. A total of 184 sources were confirmed as [O III]
emitters at a mean redshift z=0.83. The minimum detectable line flux and
equivalent width (EW) in this ELS sample are 5 10 erg
s cm and 6 \AA, respectively. We are able to constrain the
faint-end slope () of the observed LF([O III]) at
z=0.83. This LF reaches values that are approximately ten times lower than
those from other surveys. The vast majority (84\%) of the morphologically
classified [O III] ELSs are disc-like sources, and 87\% of this sample is
comprised of galaxies with stellar masses of M 10
M.Comment: v1: 16 pages, 6 figures. Accepted in Astronomy \& Astrophysics. v2:
Author added in metadat
Galaxy classification: deep learning on the OTELO and COSMOS databases
Context. The accurate classification of hundreds of thousands of galaxies
observed in modern deep surveys is imperative if we want to understand the
universe and its evolution. Aims. Here, we report the use of machine learning
techniques to classify early- and late-type galaxies in the OTELO and COSMOS
databases using optical and infrared photometry and available shape parameters:
either the Sersic index or the concentration index. Methods. We used three
classification methods for the OTELO database: 1) u-r color separation , 2)
linear discriminant analysis using u-r and a shape parameter classification,
and 3) a deep neural network using the r magnitude, several colors, and a shape
parameter. We analyzed the performance of each method by sample bootstrapping
and tested the performance of our neural network architecture using COSMOS
data. Results. The accuracy achieved by the deep neural network is greater than
that of the other classification methods, and it can also operate with missing
data. Our neural network architecture is able to classify both OTELO and COSMOS
datasets regardless of small differences in the photometric bands used in each
catalog. Conclusions. In this study we show that the use of deep neural
networks is a robust method to mine the cataloged dataComment: 20 pages, 10 tables, 14 figures, Astronomy and Astrophysics (in
press
Fasciola hepatica en búfalos de la Provincia de Corrientes, Argentina
Fasciola hepática (Trematoda: Digenea) es el agente etiológico de la fasciolosis de los bóvidos. En la región el parásito causa pérdidas por decomiso de hígados y falta de rendimiento productivo de los animales afectados. La enfermedad está supeditada a la presencia de huéspedes intermediarios, caracoles pulmonados de la familia Lymnaeidae, cuyas poblaciones prosperan en ambientes acuáticos. En la Provincia de Corrientes la enfermedad se conoce desde hace mucho tiempo, afectando a bovinos y ovinos; no se hallaron datos referentes al ganado bubalino (Bubalus bubalis). El objetivo de este ensayo fue determinar la presencia del parásito en búfalos de 41 establecimientos ganaderos de diferentes departamentos de la provincia citada, en los cuales existían antecedentes de la enfermedad en bovinos. Durante los años 2005 a 2008 fueron relevados respectivamente 11, 14 y 16 establecimientos bubalinos (en total 1.200 búfalos de distintos sexos y edades), obteniéndose resultados positivos en once establecimientos (26,8%). Se refrenda que la fasciolosis aparece cuando los búfalos son introducidos en lugares ocupados previamente por bovinos infestados con F. hepatica
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