Systèmes de détection digitaux par traitement numérique des impulsions X-dur pour des applications spatiales

Pour préparer les futures missions d'astronomie haute énergie, nous avons développé, à l'Institut de Recherche en Astrophysique et Planétologie de Toulouse, un système de détection pour l'imagerie et la spectroscopie des rayons X-durs. Celui-ci est basé sur un détecteur en Germanium haute pureté en configuration planaire, avec des électrodes segmentées par pistes, et vise une couverture en énergie allant de quelques keV jusqu'à quelques centaines de keV. En plus d'une réflexion très poussée au niveau de la conception du détecteur, ce projet se montre également innovant par l'utilisation extensive d'algorithmes de traitement numérique pour l'analyse des impulsions. C'est ce point qui constitue le sujet principal de cette thèse. L'astrophysique dans le domaine des rayons X-dur voit s'ouvrir une ère de grande évolution pour les années à venir. Des progrès technologiques dans la fabrication de miroirs permettent maintenant de focaliser les photons au delà de 10 keV, ce qui était une limite technique depuis de nombreuses années. L'observatoire NuSTAR de la NASA, lancé en 2012, et Astro-H (JAXA), qui sera lancé en 2015, sont les premières missions à exploiter ces nouveaux miroirs pour des énergies allant jusqu'à 80 keV. Cependant, des recherches récentes montrent que des optiques capables de focaliser au-delà de cette limite sont sur le point d'être réalisées. Avec cette nouvelle génération d'optiques, apparaît le besoin de nouveaux détecteurs capables de les exploiter pleinement. Une des principales caractéristiques du détecteur proposé à l'IRAP est la possibilité d'obtenir une localisation du point d'interaction des photons en volume, avec application immédiate pour la réduction de bruit de fond et le suivi des événements Compton permettant des mesures polarisation. À ce propos, nous avons implémenté un algorithme pour déterminer la position des interactions, ainsi que des méthodes pour réaliser la calibration du détecteur, gérer les déclenchements, réaliser la mise en forme et mesurer l'énergie. Afin d'obtenir une simulation complète du système, nous avons adapté MGS, un code Matlab déjà existant, pour la simulation de la collection de charge et de la réponse de notre détecteur, et nous avons utilisé Pspice pour modéliser l'électronique de lecture. Ces deux outils nous ont permis de générer des signaux réalistes pour tester les performances des algorithmes de traitement du signal pour la mesure d'énergie et la localisation de l'interaction. Finalement, nous présentons les premières mesures réalisées avec PheniX, prototype d'un système de détection conçu et réalisé dans le cadre d'une action de Recherche et Développement à l'IRAP, avec un financement CNES.Anticipating future mission opportunities in high-energy astronomy, the development of a hard X-ray detection system for imaging and spectrometry is in progress at the Institut de Recherche en Astrophysique et Planétologie of Toulouse. The system is based on a High-purity Germanium double sided strip detector and aims at energy coverage from a few keV to a few hundred keV. Besides the sophisticated detector design, the extensive use of digital signal processing algorithms for the analysis of the impulsion is another innovation in this project, and constitutes the main topic of this thesis. Astrophysics in the hard X-ray domain expect an era of major evolution in the upcoming years. Technological progress in mirror manufacturing allows now the focusing of photons well above 10 keV, which for many years had been the upper limit allowed by the technology. NASA's Nustar observatory, launched in 2012, and JAXA's Astro-H, to be launched in 2015, are the first missions to exploit the new mirrors for energies up to 80 keV. However, last research shows that focusing optics beyond this limit are to be expected soon. With this new generation of optics, a need for new detectors capable of exploiting the focusing capabilities is currently developing. One of the main features of the studied detector is the possibility to obtain a three dimensional location of the interaction of the photons in its volume, with immediate applications in background reduction and tracking of Compton events for polarimetry measurements. For this purpose, we implemented an estimator of the interaction position, which is presented in this work, together with the methods used for calibration, triggering, pulse shaping and energy measurement purposes. In order to develop a full simulation of the system, we have adapted to our particular case the MGS tool, an already existing Matlab code for the simulation of the charge collection processes and signal response provided by the detector, and we have used Pspice to model the analogue readout stage prior to the digitizer. Both tools have allowed us to generate realistic input signals for the testing of the performances of the signal processing algorithms in charge of the energy measurements and the location of the interaction position. Finally, we have completed the study with the first measurements obtained from PheniX, a laboratory prototype of the detection system which has been designed and manufactured in the framework of a Research and Technology action at IRAP, funded by the CNES

Is experience a useful resource for business model innovation?

[EN] Business model innovation has been proposed as a powerful strategic tool, able to offer competitive advantage, create markets and even reshape industries. Despite these powerful effects, little research has been conducted into studying and improving business model generation methods, and even less study has gone into analysing how to define new business models that can exert a disruptive effect on markets and industries. Our work tries to fill this gap, analysing whether experience encourages or discourages the generation of disruptive business models. An empirical analysis was carried out using an experimental methodology. The results seem to contradict the currently dominant Resource-Based View, but can be explained by the theory on inertia in organisations.Mateu Céspedes, JM.; March-Chorda, I. (2016). Is experience a useful resource for business model innovation?. Technology Analysis and Strategic Management. 28(10):1195-1209. doi:10.1080/09537325.2016.1182630S11951209281

Searching for better business models assessment methods

[EN] Purpose The purpose of this paper is to provide a more useful business models assessment method than the traditional intuitive one. The paper also compares both methods, in order to display what does the intuitive assessment method really assess. Design/methodology/approach An experimental approach allows the authors to generate a set of business models, in order to assess them and to compare alternative assessment methods in a quantitative manner. Findings The work proposes a scale for ex ante business models assessment consisting on eight indicators. This provides an ex ante assessment that takes into consideration a wider range of factors than the traditional intuitive assessment. The comparison between both methods shows which factors are intuitively taken into account and which are not. Research limitations/implications The research contributes to expand the business model creation framework. Practical implications A more accurate assessment will show the most promising business models that will result in higher chances of success of new business ventures. Social implications As companies and entrepreneurs hardly have the possibility to implement more than one business model, to choose the best option becomes essential. This selection could mark the threshold between success and failure, and between wealth creation and destruction. Originality/value Little research has been conducted in a field that might be really fruitful, the field of business model ex ante assessment. The work faces the challenge using an experimental methodology that allows to broaden the range of situations to study.Mateu Céspedes, JM.; March Chordà, I. (2016). Searching for better business models assessment methods. Management Decision. 54(10):2433-2446. doi:10.1108/MD-07-2015-0325S24332446541

A novel experimental approach to characterize neutron fields at high- and low-energy particle accelerators.

The characterization of particle accelerator induced neutron fields is challenging but fundamental for research and industrial activities, including radiation protection, neutron metrology, developments of neutron detectors for nuclear and high-energy physics, decommissioning of nuclear facilities, and studies of neutron damage on materials and electronic components. This work reports on the study of a novel approach to the experimental characterization of neutron spectra at two complex accelerator environments, namely the CERF, a high-energy mixed reference field at CERN in Geneva, and the Bern medical cyclotron laboratory, a facility used for multi-disciplinary research activities, and for commercial radioisotope production for nuclear medicine. Measurements were performed through an innovative active neutron spectrometer called DIAMON, a device developed to provide in real time neutron energy spectra without the need of guess distributions. The intercomparison of DIAMON measurements with reference data, Monte Carlo simulations, and with the well-established neutron monitor Berthold LB 6411, has been found to be highly satisfactory in all conditions. It was demonstrated that DIAMON is an almost unique device able to characterize neutron fields induced by hadrons at 120 GeV/c as well as by protons at 18 MeV colliding with different materials. The accurate measurement of neutron spectra at medical cyclotrons during routine radionuclide production for nuclear medicine applications is of paramount importance for the facility decommissioning. The findings of this work are the basis for establishing a methodology for producing controlled proton-induced neutron beams with medical cyclotrons

A Pathogenic Mechanism in Huntington's Disease Involves Small CAG-Repeated RNAs with Neurotoxic Activity

Huntington's disease (HD) is an autosomal dominantly inherited disorder caused by the expansion of CAG repeats in the Huntingtin (HTT) gene. The abnormally extended polyglutamine in the HTT protein encoded by the CAG repeats has toxic effects. Here, we provide evidence to support that the mutant HTT CAG repeats interfere with cell viability at the RNA level. In human neuronal cells, expanded HTT exon-1 mRNA with CAG repeat lengths above the threshold for complete penetrance (40 or greater) induced cell death and increased levels of small CAG-repeated RNAs (sCAGs), of ≈21 nucleotides in a Dicer-dependent manner. The severity of the toxic effect of HTT mRNA and sCAG generation correlated with CAG expansion length. Small RNAs obtained from cells expressing mutant HTT and from HD human brains significantly decreased neuronal viability, in an Ago2-dependent mechanism. In both cases, the use of anti-miRs specific for sCAGs efficiently blocked the toxic effect, supporting a key role of sCAGs in HTT-mediated toxicity. Luciferase-reporter assays showed that expanded HTT silences the expression of CTG-containing genes that are down-regulated in HD. These results suggest a possible link between HD and sCAG expression with an aberrant activation of the siRNA/miRNA gene silencing machinery, which may trigger a detrimental response. The identification of the specific cellular processes affected by sCAGs may provide insights into the pathogenic mechanisms underlying HD, offering opportunities to develop new therapeutic approaches

Desenvolupament d'una eina d'anàlisi de senyals de sistemes GNSS

Realitzat en col·laboració amb el centre o empresa: CNES (Toulouse

Desenvolupament d'una eina d'anàlisi de senyals de sistemes GNSS

Realitzat en col·laboració amb el centre o empresa: CNES (Toulouse

Desenvolupament d'una eina d'anàlisi de senyals de sistemes GNSS

Realitzat en col·laboració amb el centre o empresa: CNES (Toulouse

Alternative routes for 64Cu production using an 18 MeV medical cyclotron in view of theranostic applications.

Radiometals play a fundamental role in the development of personalized nuclear medicine. In particular, copper radioisotopes are attracting increasing interest since they offer a varying range of decay modes and half-lives and can be used for imaging (60Cu, 61Cu, 62Cu and 64Cu) and targeted radionuclide therapy (64Cu and 67Cu), providing two of the most promising true theranostic pairs, namely 61Cu/67Cu and 64Cu/67Cu. Currently, the most widely used in clinical applications is 64Cu, which has a unique decay scheme featuring β+-, β--decay and electron capture. These characteristics allow its exploitation in both diagnostic and therapeutic fields. However, although 64Cu has extensively been investigated in academic research and preclinical settings, it is still scarcely used in routine clinical practice due to its insufficient availability at an affordable price. In fact, the most commonly used production method involves proton irradiation of enriched 64Ni, which has a very low isotopic abundance and is therefore extremely expensive. In this paper, we report on the study of two alternative production routes, namely the 65Cu(p,pn)64Cu and 67Zn(p, α)64Cu reactions, which enable low and high 64Cu specific activities, respectively. To optimize the 64Cu production, while minimizing the mass of copper used as a target in the first case, or the co-production of other copper radioisotopes in the second case, an accurate knowledge of the production cross sections is of paramount importance. For this reason, the involved nuclear reaction cross sections were measured at the Bern medical cyclotron laboratory by irradiating enriched 65CuO and enriched 67ZnO targets. On the basis of the obtained results, the production yield and purity were calculated to assess the optimal irradiation conditions. Several production tests were performed to confirm these findings

47Sc and 46Sc cross-section measurement for an optimized 47Sc production with an 18 MeV medical PET cyclotron.

The availability of novel radionuclides plays a fundamental role in the development of personalized nuclear medicine. In particular, there is growing interest in pairs formed by two radioisotopes of the same element, the so-called true theranostic pairs, such as 61,64Cu/67Cu, 43,44Sc/47Sc and 155Tb/149,161Tb. In this case, the two radionuclides have identical kinetics and chemical reactivity, allowing to predict whether the patient will benefit from a therapeutic treatment on the basis of nuclear imaging data. 47Sc [t1/2 = 3.349 d, E [Formula: see text] = 440.9 keV (68.4%); 600.3 keV (31.6%), Eγ = 159.4 keV (68.3%)] is a promising radionuclide for theranostic applications in nuclear medicine. Its physical characteristics make it suitable for radionuclide therapy and allow SPECT imaging during treatment. Moreover, 47Sc is foreseen as the therapeutic partner of the β+-emitters 43Sc and 44Sc, both under study for PET imaging, opening new avenues towards the true theranostics concept. 47Sc can be produced by proton irradiation of an enriched 50Ti oxide target with a medical cyclotron equipped with a solid target station. To optimize the production yield and the radionuclidic purity, an accurate knowledge of the production cross sections is necessary. In this paper, we report on measurements of the production cross section of 47Sc and 46Sc using enriched 50Ti titanium oxide targets, performed at the Bern University Hospital cyclotron laboratory. On the basis of the obtained results, a study of the production yield and purity was performed to assess the optimal irradiation conditions. A production test was also carried out to confirm these findings