Translationally-invariant coupled-cluster method for finite systems

The translational invariant formulation of the coupled-cluster method is presented here at the complete SUB(2) level for a system of nucleons treated as bosons. The correlation amplitudes are solution of a non-linear coupled system of equations. These equations have been solved for light and medium systems, considering the central but still semi-realistic nucleon-nucleon S3 interaction.Comment: 16 pages, 2 Postscript figures, to be published in Nucl. Phys.

DC-Prophet: Predicting Catastrophic Machine Failures in DataCenters

When will a server fail catastrophically in an industrial datacenter? Is it possible to forecast these failures so preventive actions can be taken to increase the reliability of a datacenter? To answer these questions, we have studied what are probably the largest, publicly available datacenter traces, containing more than 104 million events from 12,500 machines. Among these samples, we observe and categorize three types of machine failures, all of which are catastrophic and may lead to information loss, or even worse, reliability degradation of a datacenter. We further propose a two-stage framework-DC-Prophet-based on One-Class Support Vector Machine and Random Forest. DC-Prophet extracts surprising patterns and accurately predicts the next failure of a machine. Experimental results show that DC-Prophet achieves an AUC of 0.93 in predicting the next machine failure, and a F3-score of 0.88 (out of 1). On average, DC-Prophet outperforms other classical machine learning methods by 39.45% in F3-score.Comment: 13 pages, 5 figures, accepted by 2017 ECML PKD

The Concept of Culture in Critical Mathematics Education

© Springer International Publishing AG, part of Springer Nature 2018. This is a post-peer-review, pre-copyedit version of a chapter published in The Philosophy of Mathematics Education Today. The final authenticated version is available online at: http://dx.doi.org/10.1007/978-3-319-77760-3A well-known critique in the research literature of critical mathematics education suggests that framing educational questions in cultural terms can encourage ethnic-cultural essentialism, obscure conflicts within cultures and promote an ethnographic or anthropological stance towards learners. Nevertheless, we believe that some of the obstacles to learning mathematics are cultural. ‘Stereotype threat’, for example, has a basis in culture. Consequently, the aims of critical mathematics education cannot be seriously pursued without including a cultural approach in educational research. We argue that an adequate conception of culture is available and should include normative/descriptive and material/ideal dyads as dialectical moments

Le fabuliste, le professeur de FLE et les méthodologies

Nous nous proposons d’examiner la place tenue par les Fables de La Fontaine dans les différentes méthodologies d’enseignement-apprentissage du FLE (français langue étrangère). Pour mener cette étude, nous avons examiné une sélection représentative de méthodes de FLE destinées à des publics d’enfants, d’adolescents et d\u27adultes, manuels généralistes de langue, mais aussi manuels plus spécifiques consacrés à la découverte de la littérature (type anthologies). Nous avons complété cette étude par celle du Français dans le monde, revue pédagogique à destination des enseignants de FLE. Les questions posées à partir du corpus retenu concernent la sélection des Fables présentées, leurs modalités de présence et d’exploitation. Nous avons choisi d’envisager la question d’un point de vue diachronique et de nous intéresser à la manière dont la place des Fables varie au gré des méthodologies. Pendant la période envisagée (des années 1950 à aujourd’hui), le texte littéraire a été tout d’abord « sacralisé », puis « désacralisé » (Gruca, 1993) ; depuis une quinzaine d’années, on observe un regain d’intérêt à son endroit, même si de nombreux freins subsistent. Notre étude montre que les Fables sont passées du statut de classique pour les apprenants de FLE à celui d’échantillon du patrimoine culturel français, et nous permet, chemin faisant, d’interroger la place de la littérature et la notion de patrimoine littéraire dans le domaine spécifique du FLE

Video-based biomechanical analysis of an unexpected Achilles tendon rupture in an Olympic sprinter

We used image-processing techniques to determine the moment (i.e., image frame) of the Achilles tendon (AT) rupture in an Olympic sprinter. This report may be unique due to the difficulty in conducting motion capture analyses during injury events. Our report includes one female Olympic sprinter, 29 years old (body mass: 56 kg, height: 1.68 m, and body mass index: 19.8 kg/m2) with a high-competitive profile history (2008 and 2012 Olympic Games participation; South American record holder in 100- and 200-m; Pan-American gold medalist in 200-m and 4 x 100-m relay) who suffered a complete AT rupture in the left leg while exercising in the final phase of rehabilitation following an Achilles tendinopathy in the contralateral limb. The greater dorsiflexion found at the moment of the injury and the delayed control of heel position indicated the presence of uncontrolled dorsiflexion, which potentially generated excessive eccentric stress over the tendon and, thus, the AT rupture. Here we discuss the relevance of lower leg alignment, the movements’ characteristics, and the history of Achilles tendinopathy in the contralateral leg on the occurrence of the AT rupture

Phenomenological High Precision Neutron-Proton Delta-Shell Potential

We provide a successful fit for proton-neutron scattering below pion production threshold up to LAB energies of 350 MeV. We use seven high-quality fits based on potentials with different forms as a measure of the systematic uncertainty. We represent the interaction as a sum of delta-shells in configuration space below the 3fm and a charge dependent one pion exchange potential above 3fm together with magnetic and vacuum polarization effects. Special attention is paid to estimate the errors of the phenomenological interaction.Comment: 5 pages, 2 figures. Comments and one figure with differential observables adde

First application of the Trojan Horse Method with a Radioactive Ion Beam: study of the 18^{18}F(p,αp,{\alpha})15^{15}O}} reaction at astrophysical energies

Measurement of nuclear cross sections at astrophysical energies involving unstable species is one of the most challenging tasks in experimental nuclear physics. The use of indirect methods is often unavoidable in this scenario. In this paper the Trojan Horse Method is applied for the first time to a radioactive ion beam induced reaction studying the $^{18}$F($p,{\alpha}$)$^{15}$O process at low energies relevant to astrophysics via the three body reaction $^{2}$H($^{18}$F,${\alpha}^{15}$O)n. The knowledge of the $^{18}$F($p, {\alpha}$)$^{15}$O reaction rate is crucial to understand the nova explosion phenomena. The cross section of this reaction is characterized by the presence of several resonances in $^{19}$Ne and possibly interference effects among them. The results reported in Literature are not satisfactory and new investigations of the $^{18}$F($p,{\alpha}$)$^{15}$O reaction cross section will be useful. In the present work the spin-parity assignments of relevant levels have been discussed and the astrophysical S-factor has been extracted considering also interference effectsComment: 7 pages, 4 figure

Welsh Primary Schoolchildren's Perceptions of Electronic Cigarettes: A Mixed Methods Study.

There are concerns that the growing popularity of e-cigarettes promotes experimentation among children. Given the influence of the early years on attitude and habit formation, better understanding of how younger children perceive vaping before experimentation begins is needed, to prevent uptake and inform tobacco control strategies. We explored Welsh primary schoolchildren's (aged 7-11) awareness of e-cigarettes relative to tobacco smoking, their understanding of the perceived risks and benefits and their intentions and beliefs about vaping. Data was collected using a mix of methods in June and July 2017 from 8 purposively selected primary schools across Wales. Four hundred and ninety-five children (52% female) aged 7 years (n = 165), 9 years (n = 185) and 11 years (n = 145) completed a class-administered booklet encompassing a draw and write exercise and survey. Ninety-six children participated in 24 peer discussion groups comprised of 2 boys and 2 girls from each year group. Data were analysed independently and findings triangulated. Survey analyses used frequencies, descriptive statistics and chi-squared tests. Content analysis was undertaken on the draw and write data and peer discussion groups were analysed thematically. Study findings highlight that primary schoolchildren have general awareness of e-cigarettes. Vaping was perceived to be healthier than smoking and there was some recognition that e-cigarettes were used for smoking cessation. Understanding of any health harms was limited. Few children intended to smoke or vape in the future but almost half thought it was okay for grownups. Children's perceptions were influenced by exposure through family and friends. Findings suggest a need for e-cigarette education in primary schools, to highlight the associated risks of e-cigarette experimentation including the potential for tobacco initiation

Characteristic Evolution and Matching

I review the development of numerical evolution codes for general relativity based upon the characteristic initial value problem. Progress in characteristic evolution is traced from the early stage of 1D feasibility studies to 2D axisymmetric codes that accurately simulate the oscillations and gravitational collapse of relativistic stars and to current 3D codes that provide pieces of a binary black hole spacetime. Cauchy codes have now been successful at simulating all aspects of the binary black hole problem inside an artificially constructed outer boundary. A prime application of characteristic evolution is to extend such simulations to null infinity where the waveform from the binary inspiral and merger can be unambiguously computed. This has now been accomplished by Cauchy-characteristic extraction, where data for the characteristic evolution is supplied by Cauchy data on an extraction worldtube inside the artificial outer boundary. The ultimate application of characteristic evolution is to eliminate the role of this outer boundary by constructing a global solution via Cauchy-characteristic matching. Progress in this direction is discussed.Comment: New version to appear in Living Reviews 2012. arXiv admin note: updated version of arXiv:gr-qc/050809