11,599 research outputs found
Using a Logic Programming Framework to Control Database Query Dialogues in Natural Language
We present a natural language question/answering system to interface the University of Évora databases that uses clarification dialogs in order to clarify user questions. It was developed in an integrated logic programming framework, based on constraint logic programming using the GnuProlog(-cx) language [2,11] and the ISCO framework [1]. The use of this LP framework allows the integration of Prolog-like inference mechanisms with classes and inheritance, constraint solving algorithms and provides the connection with relational databases, such as PostgreSQL. This system focus on the questions’ pragmatic analysis, to handle ambiguity, and on an efficient dialogue mechanism, which is able to place relevant questions to clarify the user intentions in a straightforward manner. Proper Nouns resolution and the pp-attachment problem are also handled.
This paper briefly presents this innovative system focusing on its ability to correctly determine the user intention through its dialogue capability
Gauge Fluctuations in Superconducting Films
In this paper we consider a superconducting film modeled by the
Ginzburg-Landau model, confined between two parallel planes a distance
apart from one another. Our approach is based on the Gaussian effective
potential in the transverse unitarity gauge, which allows to treat gauge
contributions in a compact form. Using techniques from dimensional and
-function regularizations, modified by the confinement conditions, we
investigate the critical temperature as a function of the film thickness .
The contributions from the scalar self-interaction and from the gauge
fluctuations are clearly identified. The model suggests the existence of a
minimal critical thickness below which superconductivity is suppressed.Comment: 6 pages Revtex, no figure
Bar pattern speed evolution over the last 7 Gyr
The tumbling pattern of a bar is the main parameter characterising its
dynamics. From numerical simulations, its evolution since bar formation is
tightly linked to the dark halo in which the bar is formed through dynamical
friction and angular momentum exchange. Observational measurements of the bar
pattern speed with redshift can restrict models of galaxy formation and bar
evolution. We aim to determine, for the first time, the bar pattern speed
evolution with redshift based on morphological measurements. We have selected a
sample of 44 low inclination ringed galaxies from the SDSS and COSMOS surveys
covering the redshift range 0 <z< 0.8 to investigate the evolution of the bar
pattern speed. We have derived morphological ratios between the deprojected
outer ring radius (R_{ring}) and the bar size (R_{bar}). This quantity is
related to the parameter {\cal R}=R_{CR}/R_{bar} used for classifiying bars in
slow and fast rotators, and allow us to investigate possible differences with
redshift. We obtain a similar distribution of at all redshifts. We do not
find any systematic effect that could be forcing this result. The results
obtained here are compatible with both, the bulk of the bar population (~70%)
being fast-rotators and no evolution of the pattern speed with redshift. We
argue that if bars are long-lasting structures, the results presented here
imply that there has not been a substantial angular momentum exchange between
the bar and halo, as predicted by numerical simulations. In consequence, this
might imply that the discs of these high surface-brightness galaxies are
maximal.Comment: Accepted for publication in A&
Energy dependence of ratios of multiplicities and their slopes for gluon and quark jets
The difference between the ratio of multiplicities and the ratio of their
derivatives on energy for gluon and quark jets is calculated up to
next-to-next-to leading order of perturbative QCD. Its non-zero value is
uniquely defined by the running property of the QCD coupling constant. It is
shown that this difference is rather small compared to values which can be
obtained from experimental data. This disagreement can be ascribed either to
strong non-perturbative terms or to experimental problems with a scale choice,
jets separation and inadequate assignement of soft particles to jets.Comment: 5 pages, LATEX, no Figs; submitted to JETP Let
An Inverse Problem for Localization Operators
A classical result of time-frequency analysis, obtained by I. Daubechies in
1988, states that the eigenfunctions of a time-frequency localization operator
with circular localization domain and Gaussian analysis window are the Hermite
functions. In this contribution, a converse of Daubechies' theorem is proved.
More precisely, it is shown that, for simply connected localization domains, if
one of the eigenfunctions of a time-frequency localization operator with
Gaussian window is a Hermite function, then its localization domain is a disc.
The general problem of obtaining, from some knowledge of its eigenfunctions,
information about the symbol of a time-frequency localization operator, is
denoted as the inverse problem, and the problem studied by Daubechies as the
direct problem of time-frequency analysis. Here, we also solve the
corresponding problem for wavelet localization, providing the inverse problem
analogue of the direct problem studied by Daubechies and Paul.Comment: 18 pages, 1 figur
NEW RECORDS OF INSECTS AND MITES FOR PUERTO RICO
NEW RECORDS OF INSECTS AND MITES FOR PUERTO RIC
Short term effects of irradiance on the growth of Pterocladiella capillacea (Gelidiales, Rhodophyta)
Pterocladiella capillacea has been economically exploited for agar extraction in the Azores for many years. Harvesting dropped to a full stop in the early 1990s due to a population collapse, but restarted in 2013. Since then it has been intensively harvested and overexploitation must be prevented, with both sustainable harvesting and effective cultivation practices. This study represents the first attempt to determine optimal conditions for P. capillacea production in the Azores, and evaluates its vegetative growth in two experiments using von Stosch’s medium designed to test entire thallus and tips portions response to different irradiances (30, 70 and 150 μmol photons m¯² s¯¹). The best relative growth rate (RGR) was recorded at 150 μmol photons m¯² s¯¹ for the entire thalli and tips after two-weeks and three-weeks, respectively, indicating that an acclimation period is necessary to assure the growth of this alga under experimental conditions. Higher RGR was obtained at higher irradiance (3.98 ± 2.10% fm day¯¹), but overall, growth rates were low or negative. Epiphytes were a serious problem towards the end of the entire thallus experiments, where Feldmannia irregularis proliferate at all irradiances. Future cultivation approaches complemented with other relevant environmental factors (e.g. pH, photoperiod, salinity), are recommended.FCT – Fundação para a Ciência e Tecnologia projects UID/BIA/00329/2013, 2015 - 2018 and UID/BIA/00329/2019, CIRN (Centro de Investigação de Recursos Naturais, University of the Azores), and CIIMAR (Interdisciplinary Centre of Marine and Environmental Research, Porto, Portugal). RFP was supported by a doctoral grant M3.1.2/F/024/2011, Fundo Regional para a Ciência e Tecnologia.info:eu-repo/semantics/publishedVersio
Triplectic Gauge Fixing for N=1 Super Yang-Mills Theory
The Sp(2)-gauge fixing of N = 1 super-Yang-Mills theory is considered here.
We thereby apply the triplectic scheme, where two classes of gauge-fixing
bosons are introduced. The first one depends only on the gauge field, whereas
the second boson depends on this gauge field and also on a pair of Majorana
fermions. In this sense, we build up the BRST extended (BRST plus antiBRST)
algebras for the model, for which the nilpotency relations,
s^2_1=s^2_2=s_1s_2+s_2s_1=0, hold.Comment: 10 pages, no figures, latex forma
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