Grid'5000: a large scale and highly reconfigurable grid experimental testbed

Large scale distributed systems such as Grids are difficult to study from theoretical models and simulators only. Most Grids deployed at large scale are production plat-forms that are inappropriate research tools because of their limited reconfiguration, control and monitoring capa-bilities. In this paper, we present Grid’5000, a 5000 CPU nation-wide infrastructure for research in Grid computing. Grid’5000 is designed to provide a scientific tool for com-puter scientists similar to the large-scale instruments used by physicists, astronomers, and biologists. We describe the motivations, design considerations, architec-ture, control, and monitoring infrastructure of this experi-mental platform. We present configuration examples and performance results for the reconfiguration subsystem

Are returning foreign fighters dangerous? Re-investigating Hegghammer’s assessment of the impact of veteran foreign fighters on the operational effectiveness of domestic terrorism in the West.

This paper looks at the impact of returning foreign fighters on terrorism plot effectiveness in the West by using a modified version of Hegghammer's Jihadi Plots in the West (JPW) datasets. Counter-foreign fighter policies are designed on the assumption that returning foreign fighters increase the operational effectiveness of terrorist cells and plots. Previous research on foreign fighters have provided ambiguous conclusions on the impact of their return on terrorism in the West.  In particular, researchers point to a low probability, high impact scenario where veteran foreign fighters increase the number of casualties for a given terrorist plot. This paper re-investigates these conclusions by using an updated data set. It makes use of logistic and multiple regression analysis using the difference-to-difference approach. It finds that the presence of veteran foreign fighters in terrorist cells do not increase the chances that the plot will be executed and that if the plot is executed, the presence of veteran foreign fighters has no impact on the number of casualties. In the conclusion, it argues that counter-foreign fighter policies are thus designed to prevent a very low threat. In doing so, they create potential issues by preventing the demobilization of foreign fighters. Instead, counter-foreign fighter policies should focus on reintegration in order to utilize foreign fighters to improve intelligence-gathering capabilities and create better de-radicalization programs

Le culte des reliques de Walbert et Bertille

Le culte de Walbert et Bertille, parents d’Aldegonde et de Waudru, apparaît au XIVe siècle dans l’entourage des ducs de Bourgogne grâce au témoignage de Nicolas, frère de Jacques de Guyse signalant que « saint Walbert trépassa à Coussor et y fut inhumé, son tombeau est glorifié par des miracles on voit qu’il est visité par un tel concours de pèlerins étrangers que les nôtres encourent la négligence d’impiété ». La Memoria familiale d’Aldegonde se trouvait dans une crypte de l’église dédiée, à..

A micromechanical cell stretching device compatible with super-resolution microscopy and single protein tracking

Cell mechano-sensing is based on biomolecule deformations and reorganizations, yet the molecular mechanisms are still unclear. Super-resolution microscopy (SRM) and single protein tracking (SPT) techniques reveal the dynamic organization of proteins at the nanoscale. In parallel, stretchable substrates are used to investigate cellular responses to mechanical forces. However, simultaneous combination of SRM/SPT and cell stretching has never been achieved. Here, we present a cell stretching device compatible with SRM and SPT, composed of an ultra-thin Polydimethylsiloxane (PDMS) layer. The PDMS sheet is gliding on a glycerol-lubricated glass cover-slip to ensure flatness during uniaxial stretching, generated with a 3D-printed micromechanical device by a mobile arm connected to a piezoelectric translator. This method enables to obtain super-resolved images of protein reorganization after live stretching, and to monitor single protein deformation and recruitment inside mechanosensitive structures upon stretching. This protocol is related to the publication ‘Cell stretching is amplified by active actin remodeling to deform and recruit proteins in mechanosensitive structures’, in Nature Cell Biology

A micromechanical cell stretching device compatible with super-resolution microscopy and single protein tracking

Cell mechano-sensing is based on biomolecule deformations and reorganizations, yet the molecular mechanisms are still unclear. Super-resolution microscopy (SRM) and single protein tracking (SPT) techniques reveal the dynamic organization of proteins at the nanoscale. In parallel, stretchable substrates are used to investigate cellular responses to mechanical forces. However, simultaneous combination of SRM/SPT and cell stretching has never been achieved. Here, we present a cell stretching device compatible with SRM and SPT, composed of an ultra-thin Polydimethylsiloxane (PDMS) layer. The PDMS sheet is gliding on a glycerol-lubricated glass cover-slip to ensure flatness during uniaxial stretching, generated with a 3D-printed micromechanical device by a mobile arm connected to a piezoelectric translator. This method enables to obtain super-resolved images of protein reorganization after live stretching, and to monitor single protein deformation and recruitment inside mechanosensitive structures upon stretching. This protocol is related to the publication ‘Cell stretching is amplified by active actin remodeling to deform and recruit proteins in mechanosensitive structures’, in Nature Cell Biology

Tolerance of Normal Rabbit Facial Bones and Teeth to Synchrotron X-Ray Microbeam Irradiation

Microbeam radiation therapy, an alternative radiosurgical treatment under preclinical investigation, aims to safely treat muzzle tumors in pet animals. This will require data on the largely unknown radiation toxicity of microbeam arrays for bones and teeth. To this end, the muzzle of six young adult New Zealand rabbits was irradiated by a lateral array of microplanar beamlets with peak entrance doses of 200, 330 or 500 Gy. The muzzles were examined 431 days postirradiation by computed microtomographic imaging (micro-CT) ex vivo, and extensive histopathology. The boundaries of the radiation field were identified histologically by microbeam tracks in cartilage and other tissues. There was no radionecrosis of facial bones in any rabbit. Conversely, normal incisor teeth exposed to peak entrance doses of 330 Gy or 500 Gy developed marked caries-like damage, whereas the incisors of the two rabbits exposed to 200 Gy remained unscathed. A single, unidirectional array of microbeams with a peak entrance dose ≤200 Gy (valley dose14 Gy) did not damage normal bone, teeth and soft tissues of the muzzle of normal rabbits longer than one year after irradiation. Because of that, Microbeam radiation therapy of muzzle tumors in pet animals is unlikely to cause sizeable damage to normal teeth, bone and soft tissues, if a single array as used here delivers a limited entrance dose of 200 Gy and a valley dose of ≤14 Gy

Synchrotron microbeam radiation therapy induces hypoxia in intracerebral gliosarcoma but not in the normal brain

PURPOSE Synchrotron microbeam radiation therapy (MRT) is an innovative irradiation modality based on spatial fractionation of a high-dose X-ray beam into lattices of microbeams. The increase in lifespan of brain tumor-bearing rats is associated with vascular damage but the physiological consequences of MRT on blood vessels have not been described. In this manuscript, we evaluate the oxygenation changes induced by MRT in an intracerebral 9L gliosarcoma model. METHODS Tissue responses to MRT (two orthogonal arrays (2 × 400Gy)) were studied using magnetic resonance-based measurements of local blood oxygen saturation (MR_SO2) and quantitative immunohistology of RECA-1, Type-IV collagen and GLUT-1, marker of hypoxia. RESULTS In tumors, MR_SO2 decreased by a factor of 2 in tumor between day 8 and day 45 after MRT. This correlated with tumor vascular remodeling, i.e. decrease in vessel density, increases in half-vessel distances (×5) and GLUT-1 immunoreactivity. Conversely, MRT did not change normal brain MR_SO2, although vessel inter-distances increased slightly. CONCLUSION We provide new evidence for the differential effect of MRT on tumor vasculature, an effect that leads to tumor hypoxia. As hypothesized formerly, the vasculature of the normal brain exposed to MRT remains sufficiently perfused to prevent any hypoxia

Démocratisation culturelle et numérique

La finalité de la démocratisation de la culture qui avait permis, jusqu’au milieu des années 1990, de mettre en place des objectifs stabilisés proprement culturels, a été remise en cause. Au-delà même de la cohésion sociale, d’autres desseins par la culture, comme le développement économique ou celui des territoires, sont devenus plausibles. Un changement d’échelle s’est opéré. Dans les années 2000, alors que les événements culturels ont constitué un des outils exemplaires de la démocratisation culturelle et que les institutions publiques ont notamment usé de la capacité de rassemblement des expositions et des festivals, la question des publics et de la participation de ces derniers aux grands événements culturels s’est donc posée d’une autre manière, entre individualisation des pratiques et lieux de rassemblement. Les constats sont souvent amers et semblent conduire à une nostalgie où l’écran individuel et le numérique finiraient de parachever ce qui aurait été l’aventure à bout de souffle d’une génération. Le numérique embarqué sur leurs participants interroge à nouveaux frais la réflexivité médiatique de l’événement et celle-là même, identitaire, de ses publics. La culture, l’économie, les territoires voient leur champ investi par le numérique à la fois par la volonté des acteurs et celles des politiques issues de plusieurs ministères. Faut-il pour autant en conclure que le numérique soit une révolution, un instrument sans précédent qui permet de créer des richesses culturelles devenues disponibles pour tous et permettant à tous d’y accéder de fait ? The final objective of cultural democratization which, up until the middle of the 1990s, had allowed for the establishment of stable goals within the cultural field, has now begun to be questioned. Beyond issues of social cohesion, new goals, such as economic and territorial development, have become plausibly attainable for the cultural sector. A change in scale has taken place. In the 2000s, while cultural events were seen as exemplary tools for cultural democratization and institutions took advantage of the capacity of festivals and exhibitions to bring people together, the question of audiences and their participation in such events was posed in new ways, in terms of individualizing both practices and gathering places. Conclusions have often been bittersweet and seem to lead to a sort of nostalgia for a time when a screen and digital technology would be able to tie up the loose ends of the adventure of this previous generation. Digital technology embarked upon by participants questions, in new terms, the media reflexivity of an event and thus that of the identity of audience members. Culture, economics and certain spaces find their area of influence heavily charged with technology both by the will of audiences and that of policies issues by various government ministries. Must we nonetheless conclude that digital technologies are a true revolution, an unprecedented tool capable of creating cultural riches that are available to and within the reach of all