8,721 research outputs found
Deep Learning for the Generation of Heuristics in Answer Set Programming: A Case Study of Graph Coloring
Answer Set Programming (ASP) is a well-established declarative AI formalism for knowledge representation and reasoning. ASP systems were successfully applied to both industrial and academic problems. Nonetheless, their performance can be improved by embedding domain-specific heuristics into their solving process. However, the development of domain-specific heuristics often requires both a deep knowledge of the domain at hand and a good understanding of the fundamental working principles of the ASP solvers. In this paper, we investigate the use of deep learning techniques to automatically generate domain-specific heuristics for ASP solvers targeting the well-known graph coloring problem. Empirical results show that the idea is promising: the performance of the ASP solver wasp can be improved
The Estimation of the Effective Centre of Mass Energy in q-qbar-gamma Events from DELPHI
The photon radiation in the initial state lowers the energy available for the
ee collisions; this effect is particularly important at LEP2 energies
(above the mass of the Z boson). Being aligned to the beam direction, such
initial state radiation is mostly undetected. This article describes the
procedure used by the DELPHI experiment at LEP to estimate the effective
centre-of-mass energy in hadronic events collected at energies above the Z
peak. Typical resolutions ranging from 2 to 3 GeV on the effective
center-of-mass energy are achieved, depending on the event topology.Comment: 12 pages, 6 figure
The integrability of Lie-invariant geometric objects generated by ideals in the Grassmann algebra
We investigate closed ideals in the Grassmann algebra serving as bases of
Lie-invariant geometric objects studied before by E. Cartan. Especially, the E.
Cartan theory is enlarged for Lax integrable nonlinear dynamical systems to be
treated in the frame work of the Wahlquist Estabrook prolongation structures on
jet-manifolds and Cartan-Ehresmann connection theory on fibered spaces. General
structure of integrable one-forms augmenting the two-forms associated with a
closed ideal in the Grassmann algebra is studied in great detail. An effective
Maurer-Cartan one-forms construction is suggested that is very useful for
applications. As an example of application the developed Lie-invariant
geometric object theory for the Burgers nonlinear dynamical system is
considered having given rise to finding an explicit form of the associated Lax
type representation
The analysis of glutamate and glutamine frequencies in human proteins as marker of tissue oxygenation
relA over-expression reduces tumorigenicity and activates apoptosis in human cancer cells
We previously demonstrated that bcl-2 over-expression increases the malignant behaviour of the MCF7 ADR human breast cancer cell line and enhances nuclear factor-kappa B (NF-k B) transcriptional activity. Here, we investigated the direct effect of increased NF-k B activity on the tumorigenicity of MCF7 ADR cells by over-expressing the NF-k B subunit relA/p65. Surprisingly, our results demonstrated that over-expression of relA determines a considerable reduction of the tumorigenic ability in nude mice as indicated by the tumour take and the median time of tumour appearance. In vitro studies also evidenced a reduced cell proliferation and the activation of the apoptotic programme after relA over-expression. Apoptosis was associated with the production of reactive oxygen species, and the cleavage of the specific substrate Poly-ADP-ribose-polymerrase. Our data indicate that there is no general role for NF-k B in the regulation of apoptosis and tumorigenicity. In fact, even though inhibiting NF-k B activity has been reported to be lethal to tumour cells, our findings clearly suggest that an over-induction of nuclear NF-k B activity may produce the same effect. © 2001 Cancer Research Campaign http://www.bjcancer.co
Combined Theoretical and Experimental Study of the Moiré Dislocation Network at the SrTiO3-(La,Sr)(Al,Ta)O3 Interface.
Recently, a highly ordered Moiré dislocation lattice was identified at the interface between a SrTiO3 (STO) thin film and the (LaAlO3)0.3(Sr2TaAlO6)0.7 (LSAT) substrate. A fundamental understanding of the local ionic and electronic structures around the dislocation cores is crucial to further engineer the properties of these complex multifunctional heterostructures. Here, we combine experimental characterization via analytical scanning transmission electron microscopy with results of molecular dynamics and density functional theory calculations to gain insights into the structure and defect chemistry of these dislocation arrays. Our results show that these dislocations lead to undercoordinated Ta/Al cations at the dislocation core, where oxygen vacancies can easily be formed, further facilitated by the presence of cation vacancies. The reduced Ti3+ observed experimentally at the dislocations by electron energy-loss spectroscopy is a consequence of both the structure of the dislocation itself and of the electron doping due to oxygen vacancy formation. Finally, the experimentally observed Ti diffusion into the LSAT around the dislocation core occurs only together with cation vacancy formation in the LSAT or Ta diffusion into STO
Combined theoretical and experimental study of the Moir\'e dislocation network at the SrTiO-(La,Sr)(Al,Ta)O interface
Recently a highly ordered Moir\'e dislocation lattice was identified at the
interface between a \ce{SrTiO3} (STO) thin film and the
(LaAlO)(SrTaAlO) (LSAT) substrate. A fundamental
understanding of the local ionic and electronic structure around the
dislocation cores is crucial to further engineer the properties of these
complex multifunctional heterostructures. Here we combine experimental
characterization via analytical scanning transmission electron microscopy with
results of molecular dynamics and density functional theory calculations to
gain insights into the structure and defect chemistry of these dislocation
arrays. Our results show that these dislocations lead to undercoordinated Ta/Al
cations at the dislocation core, where oxygen vacancies can easily be formed,
further facilitated by the presence of cation vacancies. The reduced Ti
observed experimentally at the dislocations by electron energy-loss
spectroscopy are a consequence of both the structure of the dislocation itself,
as well as of the electron-doping due to oxygen vacancy formation. Finally, the
experimentally observed Ti diffusion into LSAT around the dislocation core
occurs only together with cation-vacancy formation in LSAT or Ta diffusion into
STO
Evidence for the naphthalene cation in a region of the interstellar medium with anomalous microwave emission
We report high resolution spectroscopy of the moderately reddened (A=3)
early type star Cernis 52 located in a region of the Perseus molecular cloud
complex with anomalous microwave emission. In addition to the presence of the
most common diffuse interstellar bands (DIBs) we detect two new interstellar or
circumstellar bands coincident to within 0.01% in wavelength with the two
strongest bands of the naphthalene cation (CH) as measured in
gas-phase laboratory spectroscopy at low temperatures and find marginal
evidence for the third strongest band.
Assuming these features are caused by the naphthalene cation, from the
measured intensity and available oscillator strengths we find that 0.008 % of
the carbon in the cloud could be in the form of this molecule. We expect
hydrogen additions to cause hydronaphthalene cations to be abundant in the
cloud and to contribute via electric dipole radiation to the anomalous
microwave emission. The identification of new interstellar features consistent
with transitions of the simplest polycyclic aromatic hydrocarbon adds support
to the hypothesis that this type of molecules are the carriers of both diffuse
interstellar bands and anomalous microwave emission.Comment: Accepted for publication in The Astrophysical Journa
Ilustración, Modernidad e Identidad en América latina
El objetivo del presente Proyecto es el de posibilitar un ámbito de investigación, de discusión y de crítica, acerca de las Implicaciones éticas y políticas en el discurso sobre el bicentenario de América Latina, acontecimiento que se conmemorará en buena parte de los países de la región a partir del año 2010. Se considera que el problema sobre el cual recae el Proyecto, a saber, Ilustración, Modernidad e identidad social en América Latina, cumple con el objetivo enunciado, en otras palabras, resulta pertinente y relevante. En efecto, resulta pertinente, según consideramos, pues trabaja una problemática que permite comprender y eventualmente explicar los movimientos independentistas que se dieron en varios países de América Latina en las primeras décadas del siglo 19. También es relevante, dado que suministra elementos necesarios para reflexionar y analizar sobre las consecuencias actuales, éticas y políticas, de aquellos acontecimientos. Se trabajan los siguientes aspectos. En primer lugar, se intenta mostrar la relación histórica entre la gesta independentista, el fenómeno de la Ilustración y el problema de la identidad. En segundo lugar, se incluye a la Ilustración como un aspecto central de la Modernidad y se plantean las relaciones entre Modernidad e Identidad en general y en América Latina, en particular, relevándose los antecedentes bibliográficos sobre la cuestión
Algorithms for Stable Matching and Clustering in a Grid
We study a discrete version of a geometric stable marriage problem originally
proposed in a continuous setting by Hoffman, Holroyd, and Peres, in which
points in the plane are stably matched to cluster centers, as prioritized by
their distances, so that each cluster center is apportioned a set of points of
equal area. We show that, for a discretization of the problem to an
grid of pixels with centers, the problem can be solved in time , and we experiment with two slower but more practical algorithms and
a hybrid method that switches from one of these algorithms to the other to gain
greater efficiency than either algorithm alone. We also show how to combine
geometric stable matchings with a -means clustering algorithm, so as to
provide a geometric political-districting algorithm that views distance in
economic terms, and we experiment with weighted versions of stable -means in
order to improve the connectivity of the resulting clusters.Comment: 23 pages, 12 figures. To appear (without the appendices) at the 18th
International Workshop on Combinatorial Image Analysis, June 19-21, 2017,
Plovdiv, Bulgari
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