35,723 research outputs found
Automatic case acquisition from texts for process-oriented case-based reasoning
This paper introduces a method for the automatic acquisition of a rich case
representation from free text for process-oriented case-based reasoning. Case
engineering is among the most complicated and costly tasks in implementing a
case-based reasoning system. This is especially so for process-oriented
case-based reasoning, where more expressive case representations are generally
used and, in our opinion, actually required for satisfactory case adaptation.
In this context, the ability to acquire cases automatically from procedural
texts is a major step forward in order to reason on processes. We therefore
detail a methodology that makes case acquisition from processes described as
free text possible, with special attention given to assembly instruction texts.
This methodology extends the techniques we used to extract actions from cooking
recipes. We argue that techniques taken from natural language processing are
required for this task, and that they give satisfactory results. An evaluation
based on our implemented prototype extracting workflows from recipe texts is
provided.Comment: Sous presse, publication pr\'evue en 201
Spatial and temporal phylogeny of border disease virus in pyrenean chamois (Rupicapra p. Pyrenaica)
Border disease virus (BDV) affects a wide range of ruminants worldwide, mainly domestic sheep and goat. Since 2001 several outbreaks of disease associated to BDV infection have been described in Pyrenean chamois (Rupicapra pyrenaica pyrenaica) in Spain, France and Andorra. In order to reconstruct the most probable places of origin and pathways of dispersion of BDV among Pyrenean chamois, a phylogenetic analysis of 95 BDV 5'untranslated sequences has been performed on chamois and domestic ungulates, including novel sequences and retrieved from public databases, using a Bayesian Markov Chain Monte Carlo method. Discrete and continuous space phylogeography have been applied on chamois sequences dataset, using centroid positions and latitude and longitude coordinates of the animals, respectively.
The estimated mean evolutionary rate of BDV sequences was 2.9x10(-3) subs/site/year (95% HPD: 1.5-4.6x10(-3)). All the Pyrenean chamois isolates clustered in a unique highly significant clade, that originated from BDV-4a ovine clade. The introduction from sheep (dated back to the early 90s) generated a founder effect on the chamois population and the most probable place of origin of Pyrenean chamois BDV was estimated at coordinates 42.42 N and 1.9 E. The pathways of virus dispersion showed two main routes: the first started on the early 90s of the past century with a westward direction and the second arise in Central Pyrenees. The virus spread westward for more than 125 km and southward for about 50km and the estimated epidemic diffusion rate was about 13.1 km/year (95% HPD 5.2-21.4 km/year). The strong spatial structure, with strains from a single locality segregating together in homogeneous groups, and the significant pathways of viral dispersion among the areas, allowed to reconstruct both events of infection in a single area and of migrations, occurring between neighboring areas
Identification of activity peaks in time-tagged data with a scan-statistics driven clustering method and its application to gamma-ray data samples
The investigation of activity periods in time-tagged data-samples is a topic
of large interest. Among Astrophysical samples, gamma-ray sources are widely
studied, due to the huge quasi-continuum data set available today from the
FERMI-LAT and AGILE-GRID gamma-ray telescopes. To reveal flaring episodes of a
given gamma-ray source, researchers make use of binned light-curves. This
method suffers several drawbacks: the results depends on time-binning, the
identification of activity periods is difficult for bins with low signal to
noise ratio. I developed a general temporal-unbinned method to identify flaring
periods in time-tagged data and discriminate statistically-significant flares:
I propose an event clustering method in one-dimension to identify flaring
episodes, and Scan-statistics to evaluate the flare significance within the
whole data sample. This is a photometric algorithm. The comparison of the
photometric results (e.g., photometric flux, gamma-ray spatial distribution)
for the identified peaks with the standard likelihood analysis for the same
period is mandatory to establish if source-confusion is spoiling results. The
procedure can be applied to reveal flares in any time-tagged data sample. The
study of the gamma ray activity of 3C 454.3 and of the fast variability of the
Crab Nebula are shown as examples. The result of the proposed method is similar
to a photometric light curve, but peaks are resolved, they are statistically
significant within the whole period of investigation, and peak detection
capability does not suffer time-binning related issues. The method can be
applied for gamma-ray sources of known celestial position. Furthermore the
method can be used when it is necessary to assess the statistical significance
within the whole period of investigation of a flare from an unknown gamma-ray
source.Comment: 17 pages, 10 figures Accepted for publication in A&
Measuring the Performance of Beat Tracking Algorithms Using a Beat Error Histogram
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Above and Beyond the Landauer Bound: Thermodynamics of Modularity
Information processing typically occurs via the composition of modular units,
such as universal logic gates. The benefit of modular information processing,
in contrast to globally integrated information processing, is that complex
global computations are more easily and flexibly implemented via a series of
simpler, localized information processing operations which only control and
change local degrees of freedom. We show that, despite these benefits, there
are unavoidable thermodynamic costs to modularity---costs that arise directly
from the operation of localized processing and that go beyond Landauer's
dissipation bound for erasing information. Integrated computations can achieve
Landauer's bound, however, when they globally coordinate the control of all of
an information reservoir's degrees of freedom. Unfortunately, global
correlations among the information-bearing degrees of freedom are easily lost
by modular implementations. This is costly since such correlations are a
thermodynamic fuel. We quantify the minimum irretrievable dissipation of
modular computations in terms of the difference between the change in global
nonequilibrium free energy, which captures these global correlations, and the
local (marginal) change in nonequilibrium free energy, which bounds modular
work production. This modularity dissipation is proportional to the amount of
additional work required to perform the computational task modularly. It has
immediate consequences for physically embedded transducers, known as
information ratchets. We show how to circumvent modularity dissipation by
designing internal ratchet states that capture the global correlations and
patterns in the ratchet's information reservoir. Designed in this way,
information ratchets match the optimum thermodynamic efficiency of globally
integrated computations.Comment: 17 pages, 9 figures;
http://csc.ucdavis.edu/~cmg/compmech/pubs/idolip.ht
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