The Unresolved Land Reform Debate: Beyond State-Led or Market-Led Models

Land Reform; Debate; State-Led; Market-Led; Model

A Bootstrapping architecture for time expression recognition in unlabelled corpora via syntactic-semantic patterns

In this paper we describe a semi-supervised approach to the extraction of time expression mentions in large unlabelled corpora based on bootstrapping. Bootstrapping techniques rely on a relatively small amount of initial human-supplied examples (termed “seeds”) of the type of entity or concept to be learned, in order to capture an initial set of patterns or rules from the unlabelled text that extract the supplied data. In turn, the learned patterns are employed to find new potential examples, and the process is repeated to grow the set of patterns and (optionally) the set of examples. In order to prevent the learned pattern set from producing spurious results, it becomes essential to implement a ranking and selection procedure to filter out “bad” patterns and, depending on the case, new candidate examples. Therefore, the type of patterns employed (knowledge representation) as well as the ranking and selection procedure are paramount to the quality of the results. We present a complete bootstrapping algorithm for recognition of time expressions, with a special emphasis on the type of patterns used (a combination of semantic and morpho- syntantic elements) and the ranking and selection criteria. Bootstrap- ping techniques have been previously employed with limited success for several NLP problems, both of recognition and classification, but their application to time expression recognition is, to the best of our knowledge, novel. As of this writing, the described architecture is in the final stages of implementation, with experimention and evalution being already underway.Postprint (published version

Topic modeling for entity linking using keyphrase

This paper proposes an Entity Linking system that applies a topic modeling ranking. We apply a novel approach in order to provide new relevant elements to the model. These elements are keyphrases related to the queries and gathered from a huge Wikipedia-based knowledge resourcePeer ReviewedPostprint (author’s final draft

Detecting entanglement of two electron spin qubits with witness operators

We propose a scheme for detecting entanglement between two electron spin qubits in a double quantum dot using an entanglement witness operator. We first calculate the optimal configuration of the two electron spins, defined as the position in the energy level spectrum where, averaged over the nuclear spin distribution, 1) the probability to have two separated electrons, and 2) the degree of entanglement of the quantum state quantified by the concurrence are both large. Using a density matrix approach, we then calculate the evolution of the expectation value of the witness operator for the two-spin singlet state, taking into account the effect of decoherence due to quantum charge fluctuations modeled as a boson bath. We find that, for large interdot coupling, it is possible to obtain a highly entangled and robust ground state.Comment: 4 pages, 3 figure

Collisional and thermal dissociation of J/ψJ/\psi and Υ\Upsilon states at the LHC

We present new results for the suppression of high transverse momentum charmonium [$J/\psi, \psi(2S)$] and bottomonium [$\Upsilon(1S),\Upsilon(2S),\Upsilon(3S)$] states in Pb+Pb collisions at the Large Hadron Collider. Our theoretical formalism combines the collisional dissociation of quarkonia, as they propagate in the quark-gluon plasma, with the thermal wavefunction effects due to the screening of the $Q\bar{Q}$ attractive potential in the medium. We find that a good description of the relative suppression of the ground and higher excited quarkonium states, transverse momentum and centrality distributions is achieved, when comparison to measurements at a center-of-mass energy of 2.76 TeV is performed. Theoretical predictions for the highest Pb+Pb center-of-mass energy of 5.02 TeV at the LHC, where new experimental results are being finalized, are also presented.Comment: 8 pages, 8 eps figures; 2 figures and references added, introduction restructured; version to appear in PL

Mesure du Bs0B_{s}^{0} de plus court temps de vie dans le cadre de l'expérience LHCb

L'expérience LHCb est une expérience de seconde génération dédiée à l'étude de la violation de la symétrie CP dans les systèmes des hadrons beaux. La symétrie CP est la combinaison de la symétrie de conjugaison de charge (C) qui échange particule et anti-particule et de la symétrie de parité (P) qui inverse les directions d'espace. L'ensemble des hadrons beaux est produit. Son détecteur sera l'un des quatre devant être installé sur le grand collisionneur de protons (LHC). Dans l'objectif de tester la validité du modèle standard dans ce domaine, il sera nécessaire d'effectuer une série de mesures de précision concernant les paramètres qui définissent la violation de CP et les grandeurs physiques caractérisant le mélange et la désintégration des hadrons beaux. Ce document décrit la probabilité de mesure de la différence relative de largeur de désintégration dans le système du méson $B_{s}^{0}$ ($\frac{\Delta{\Gamma_s}}{\Gamma_s}$) à travers l'étude du canal $B_{s}^{0}\rightarrow\,D_{s}^{+}\,D_{s}^{-}

Entanglement and the Quantum Brachistochrone Problem

Entanglement is closely related to some fundamental features of the dynamics of composite quantum systems: quantum entanglement enhances the "speed" of evolution of certain quantum states, as measured by the time required to reach an orthogonal state. The concept of "speed" of quantum evolution constitutes an important ingredient in any attempt to determine the fundamental limits that basic physical laws impose on how fast a physical system can process or transmit information. Here we explore the relationship between entanglement and the speed of quantum evolution in the context of the quantum brachistochrone problem. Given an initial and a final state of a composite system we consider the amount of entanglement associated with the brachistochrone evolution between those states, showing that entanglement is an essential resource to achieve the alluded time-optimal quantum evolution.Comment: 6 pages, 3 figures. Corrected typos in Eqs. 1 and