Ultra High Energy neutrinos with the Pierre Auger Observatory

texte intégral disponible sur http://proc.sf2a.asso.fr/2006/2006sf2a.conf..0115B.pdfInternational audienceThe Pierre Auger Observatory was designed to observe cosmic rays of ultra-high energy. It has also the capability to observe rare neutrino-induced showers. An evaluation of the sensitivity of the Surface Detector is presented and a procedure to discriminate them from the background is described

Tierra, fuego, agua y aire: la escultura en Raku

La incorporación al Espacio Europeo de Educación Superior, ha traído consigo cambios metodológicos docentes. Los departamentos de Escultura y Pintura de la Facultad de Bellas Artes no han querido ser ajenos a ellos y desde los mismos varios profesores hemos diseñado y llevado a cabo una actividad docente común centrada en los alumnos a través de la técnica del aprendizaje activo. Estudiantes de tercero, cuarto y quinto curso de licenciatura y grado han ejercitado diferentes competencias profesionales partiendo de un problema común propuesto: el diseño y construcción de un horno artesanal y la ideación y realización de esculturas cociéndolas en el mismo con la técnica del raku. El objetivo no era únicamente la resolución del problema sino que el alumno fuera capaz de adquirir y aplicar todo un conjunto de conocimientos tanto teóricos como prácticos de la disciplina convirtiéndose en protagonista de su propio aprendizaje. Los resultados se plasmaron posteriormente en la exposición de las obras y en la publicación del desarrollo del proceso en el campus virtualPeer Reviewe

Calculation of Raman optical activity spectra for vibrational analysis

By looking back on the history of Raman Optical Activity (ROA), the present article shows that the success of this analytical technique was for a long time hindered, paradoxically, by the deep level of detail and wealth of structural information it can provide. Basic principles of the underlying theory are discussed, to illustrate the technique's sensitivity due to its physical origins in the delicate response of molecular vibrations to electromagnetic properties. Following a short review of significant advances in the application of ROA by UK researchers, we dedicate two extensive sections to the technical and theoretical difficulties that were overcome to eventually provide predictive power to computational simulations in terms of ROA spectral calculation. In the last sections, we focus on a new modelling strategy that has been successful in coping with the dramatic impact of solvent effects on ROA analyses. This work emphasises the role of complementarity between experiment and theory for analysing the conformations and dynamics of biomolecules, so providing new perspectives for methodological improvements and molecular modelling development. For the latter, an example of a next-generation force-field for more accurate simulations and analysis of molecular behaviour is presented. By improving the accuracy of computational modelling, the analytical capabilities of ROA spectroscopy will be further developed so generating new insights into the complex behaviour of molecules

The Raman optical activity of β-D-xylose: where experiment and theory meet

Besides its applications in bioenergy and biosynthesis, β-D-xylose is a very simple monosaccharide that exhibits relatively high rigidity. As such, it provides the best basis to study the impact of different solvation shell radii on the computation of its Raman optical activity (ROA) spectrum. Indeed, this chiroptical spectroscopic technique provides exquisite sensitivity to stereochemistry, and benefits much from theoretical support for interpretation. Our simulation approach combines density functional theory (DFT) and molecular dynamics (MD) in order to efficiently account for the crucial hydration effects in the simulation of carbohydrates and their spectroscopic response predictions. Excellent agreement between the simulated spectrum and the experiment was obtained with a solvation radius of 10 Å. Vibrational bands have been resolved from the computed ROA data, and compared with previous results on different monosaccharides in order to identify specific structure–spectrum relationships and to investigate the effect of the solvation environment on the conformational dynamics of small sugars. From the comparison with ROA analytical results, a shortcoming of the classical force field used for the MD simulations has been identified and overcome, again highlighting the complementary role of experiment and theory in the structural characterisation of complex biomolecules. Indeed, due to unphysical puckering, a spurious ring conformation initially led to erroneous conformer ratios, which are used as weights for the averaging of the spectral average, and only by removing this contribution was near perfect comparison between theory and experiment achieved

Distinguishing epimers through raman optical activity

The Raman optical activity spectra of the epimers β-d-glucose and β-d-galactose, two monosaccharides of biological importance, have been calculated using molecular dynamics combined with a quantum mechanics/molecular mechanics approach. Good agreement between theoretical and experimental spectra is observed for both monosaccharides. Full band assignments have been carried out, which has not previously been possible for carbohydrate epimers. For the regions where the spectral features are opposite in sign, the differences in the vibrational modes have been noted and ascribed to the band sign changes

EFFECTS OF BALANCING HAMSTRING AND QUADRICEPS MUSCLE TORQUE ON RUNNING TECHNIQUE

It has been suggested that balancing the isokinetic strength of quadriceps (Q) and hamstring (H) muscles can reduce hamstring injuries during running (Croisier et al 2008). The efficacy of this type of intervention has been previously explored. To further the knowledge of the H: Q relationship we have examined the intervention’s affect on running technique as presented here

Different tissue type categories of overuse injuries to cricket fast bowlers have different severity and incidence which varies with age

Background. Cricket fast bowlers have a high incidence of injury and have been the subject of previous research investigating the effects of previous injury, workload and technique. Bone stress injuries are of particular concern as they lead to prolonged absences from the game, with younger bowlers appearing to be at particular risk. Objectives. To investigate the variation in severity and incidence of injury to different tissue types in fast bowlers and ascertain whether age is a significant risk factor for these injuries. Methods. A retrospective analysis of match bowling exposure in 215 separate fast bowlers over a 14-year period was undertaken. This information was amalgamated with injury surveillance data providing information on the incidence, location, tissue type and severity of injury. Age of the bowler was determined and the bowlers were stratified into five age groups to determine the influence of age on the injury variables. Results. Younger bowlers (less than 22 years old) were 3.7-6.7 times more likely to suffer a bony injury than all the other age groups. Older bowlers (greater than 31 years old) were 2.2-2.7 times more likely to suffer a tendon injury than the 3 youngest groups. Conclusion. This study has demonstrated that younger age is a considerable risk factor in the development of bone stress injuries in cricket fast bowlers. In addition there appears to be a higher incidence of tendon injuries in older fast bowlers although this may be explained by the current classification system of joint impingement as a tendon injury. Keywords. Bone, tendon, sports injurie

Tau energy losses at ultra-high energy: continuous versus stochastic treatment

We study the energy losses of the tau lepton in matter through electromagnetic processes at ultra-high energy (UHE). We use both a stochastic and a continuous framework to treat these interactions and compare the flux of tau leptons propagated after some amount of matter. We discuss the accuracy of the approximation of continuous energy losses by studying the propagation in standard rock of taus with both mono-energetic and power law injection spectra.Comment: 7 pages, 8 figure

SHORT-TERM PLYOMETRIC TRAINING IMPROVES ALTERED NEUROMOTOR CONTROL DURING RUNNING AFTER CYCLING IN TRIATHLETES

Cycling has a direct negative effect on some highly-trained triathletes’ ability to execute optimal neuromotor strategies specific to running (Chapman et al., 2008). The presence of altered neuromotor control when running off-the-bike has been associated with exercise-related leg pain (Chapman et al., 2010). Accordingly, identification of training interventions that could minimise this interference may aid in prevention of injury and augmentation of performance during running following cycling. Plyometric training is a specific form of strength training that has been reported to improve running economy by enhancing neuromuscular function (Paavolainen et al., 1999). The primary aim of this study was to examine the effect of plyometric training on triathletes neuromotor control and running economy in those in which neuromotor control is aberrant during running after cycling