Beyond Stemming and Lemmatization: Ultra-stemming to Improve Automatic Text Summarization

In Automatic Text Summarization, preprocessing is an important phase to reduce the space of textual representation. Classically, stemming and lemmatization have been widely used for normalizing words. However, even using normalization on large texts, the curse of dimensionality can disturb the performance of summarizers. This paper describes a new method for normalization of words to further reduce the space of representation. We propose to reduce each word to its initial letters, as a form of Ultra-stemming. The results show that Ultra-stemming not only preserve the content of summaries produced by this representation, but often the performances of the systems can be dramatically improved. Summaries on trilingual corpora were evaluated automatically with Fresa. Results confirm an increase in the performance, regardless of summarizer system used.Comment: 22 pages, 12 figures, 9 table

Stretchable electronics for artificial skin

Postprint (published version

Discrimination in the Private Sphere. A subjective Right or a Legal Abuse. An European North American Legal Comparative Study

En el presente trabajo se estudian los límites de la autonomía privada desde la perspectiva del derecho a la igualdad y del principio de no discriminación tanto en el derecho norteamericano como en el europeo, con especial incidencia a la doctrina española. Por un lado se plantea si la piedra angular a la hora de establecer límites a la autonomía privada debe ser el concepto de dignidad o el de igualdad, por otro superando dicho debate se propone un acercamiento al problema entendido como una colisión entre derechos fundamentales en la que en cada concreto supuesto ha de estudiarse cual debe prevalecer. Finalmente se estima conveniente seguir el modelo de la Constitución de Sudáfrica y entender que los derechos fundamentales afectan directamente tanto a las relaciones horizontales como verticales, es decir tanto al ámbito público como privado.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Chiral transport equation from the quantum Dirac Hamiltonian and the on-shell effective field theory

We derive the relativistic chiral transport equation for massless fermions and antifermions by performing a semiclassical Foldy-Wouthuysen diagonalization of the quantum Dirac Hamiltonian. The Berry connection naturally emerges in the diagonalization process to modify the classical equations of motion of a fermion in an electromagnetic field. We also see that the fermion and antifermion dispersion relations are corrected at first order in the Planck constant by the Berry curvature, as previously derived by Son and Yamamoto for the particular case of vanishing temperature. Our approach does not require knowledge of the state of the system, and thus it can also be applied at high temperature. We provide support for our result by an alternative computation using an effective field theory for fermions and antifermions: the on-shell effective field theory. In this formalism, the off-shell fermionic modes are integrated out to generate an effective Lagrangian for the quasi-on-shell fermions/antifermions. The dispersion relation at leading order exactly matches the result from the semiclassical diagonalization. From the transport equation, we explicitly show how the axial and gauge anomalies are not modified at finite temperature and density despite the incorporation of the new dispersion relation into the distribution function.Comment: 9 pages, no figures. v2: Some comments and more details added, typos fixed and reference list updated. Final version matching the published articl

Perturbative quantum analysis and classical limit of the electron scattering by a solenoidal magnetic field

A well known example in quantum electrodynamics (QED) shows that Coulomb scattering of unpolarized electrons, calculated to lowest order in perturbation theory, yields a results that exactly coincides (in the non-relativistic limit) with the Rutherford formula. We examine an analogous example, the classical and perturbative quantum scattering of an electron by a magnetic field confined in an infinite solenoid of finite radius. The results obtained for the classical and the quantum differential cross sections display marked differences. While this may not be a complete surprise, one should expect to recover the classical expression by applying the classical limit to the quantum result. This turn not to be the case. Surprisingly enough, it is shown that the classical result can not be recuperated even if higher order corrections are included. To recover the classic correspondence of the quantum scattering problem a suitable non-perturbative methodology should be applied.Comment: To appear in the proceedings of 13th Mexican School of Particles and Fields (MSPF 2008), San Carlos, Sonora, Mexico, 2-11 Oct 2008. 6 pages, 2 Postscript figure