Controlling front-end electronics boards using commercial solutions

LHCb is a dedicated B-physics experiment under construction at CERN's large hadron collider (LHC) accelerator. This paper will describe the novel approach LHCb is taking toward controlling and monitoring of electronics boards. Instead of using the bus in a crate to exercise control over the boards, we use credit-card sized personal computers (CCPCs) connected via Ethernet to cheap control PCs. The CCPCs will provide a simple parallel, I2C, and JTAG buses toward the electronics board. Each board will be equipped with a CCPC and, hence, will be completely independently controlled. The advantages of this scheme versus the traditional bus-based scheme will be described. Also, the integration of the controls of the electronics boards into a commercial supervisory control and data acquisition (SCADA) system will be shown. (5 refs)

Paper-based enzymatic microfluidic fuel cell: From a two-stream flow device to a single-stream lateral flow strip

This work presents a first approach towards the development of a cost-effective enzymatic paper-based glucose/O2 microfluidic fuel cell in which fluid transport is based on capillary action. A first fuel cell configuration consists of a Y-shaped paper device with the fuel and the oxidant flowing in parallel over carbon paper electrodes modified with bioelectrocatalytic enzymes. The anode consists of a ferrocenium-based polyethyleneimine polymer linked to glucose oxidase (GOx/Fc-C6-LPEI), while the cathode contains a mixture of laccase, anthracene-modified multiwall carbon nanotubes, and tetrabutylammonium bromide-modified Nafion (MWCNTs/laccase/TBAB-Nafion). Subsequently, the Y-shaped configuration is improved to use a single solution containing both, the anolyte and the catholyte. Thus, the electrolytes pHs of the fuel and the oxidant solutions are adapted to an intermediate pH of 5.5. Finally, the fuel cell is run with this single solution obtaining a maximum open circuit of 0.55 ± 0.04 V and a maximum current and power density of 225 ± 17 μA cm−2 and 24 ± 5 μW cm−2, respectively. Hence, a power source closer to a commercial application (similar to conventional lateral flow test strips) is developed and successfully operated. This system can be used to supply the energy required to power microelectronics demanding low power consumption.F. Javier del Campo acknowledges funding from the Spanish Ministry of Economy through the DADDi2 project (TEC2013-48506-C3). Juan Pablo Esquivel would like to thank the support from Marie Curie International Outgoing Fellowship (APPOCS-328144) within the 7th European Community Framework Programme. Shelley D. Minteer and Fabien Giroud would like to thank the National Science Foundation (CHE-1057597) for funding. Neus Sabaté acknowledges funding from the European H2020 Framework Programme (Grant Agreement 648518 - SUPERCELL - ERC 2014 CoG).Peer reviewe

Planck pre-launch status : The Planck mission

Peer reviewe

Confining Trypanosoma brucei in emulsion droplets reveals population variabilities in division rates and improves in vitro cultivation

Trypanosome parasites are infecting mammals in Sub-Saharan Africa and are transmitted between hosts through bites of the tsetse fly. The transmission from the insect vector to the mammal host causes a number of metabolic and physiological changes. A fraction of the population continuously adapt to the immune system of the host, indicating heterogeneity at the population level. Yet, the cell to cell variability in populations is mostly unknown. We develop here an analytical method for quantitative measurements at the single cell level based on encapsulation and cultivation of single-cell Trypanosoma brucei in emulsion droplets. We first show that mammalian stage trypanosomes survive for several hours to days in droplets, with an influence of droplet size on both survival and growth. We unravel various growth patterns within a population and find that droplet cultivation of trypanosomes results in 10-fold higher cell densities of the highest dividing cell variants compared to standard cultivation techniques. Some variants reach final cell titers in droplets closer to what is observed in nature than standard culture, of practical interest for cell production. Droplet microfluidics is therefore a promising tool for trypanosome cultivation and analysis with further potential for high-throughput single cell trypanosome analysis

Directed evolution and enzymatic biofuel cells,study of CotA laccase and its optimization by directed evolution using droplet based microfluidic

Les biopiles enzymatiques ont vu le jour pour développer des sources miniatures d'électricité renouvelable. Cette technologie naissante est cependant encore limitée en termes de puissance ou de durée de vie. Bien qu encore peu employée, une stratégie pourEnzymatic biofuel cells have been recently developed to create miniature renewable electricity sources. However, this new technology is still limited in terms of power and lifetime compared to classical fuel cells. Although it has been rarely used yet, o

Etudes des désintégrations de mésons beaux avec photons convertis dans l'expérience LHCbLHC_b

The LHCb experiment studies CP violation in B meson decays and will take data in 2007. Analysis strategy are studied on simulations. In this development, I worked on many fields, and essentially in: - converted photons reconstruction: the charge deposited by electrons and positrons produced by converted photons can be seen and allow to detect them. The low rate of conversion is of course to consider and the use of converted photons is advantageous only because of their good momentum measurements. - decay channels with converted photon selection: the good momentum resolution allows to select different channels, among which: B0 -> K* gamma, B0 -> pi- pi+ pi0 and B0 -> pi0 pi0. Despite low branching ratios, I show that these modes can be studied. The classical method with photons detected by the electromagnetical calorimeter being difficult, the use of converted photons will be an advantage for LHCb

Etude comportementale et de neuroimagerie fonctionnelle des signaux d'intégration du mouvement au sein de la hiérarchie corticale visuelle

Models of motion integration are ideal candidates for reviewing functional hierarchy in early visual cortex. Motion integration has been extensively studied and constitutes an influential model originally represented as a two-stage feedforward process where FB signals played no apparent role in motion perception. Within this model, low-level visual areas are proposed to linearly detect and encode one-dimensional (or “component”) motion (e.g., a single grating moving orthogonally to its orientation), while the higher-level motion detectors compute non-linear integration of more complex (or “pattern”) motion signals (e.g., two superimposed moving gratings integrated as one moving plaid). According to this view, low-level visual areas (primary and secondary visual areas, V1 and V2) and higher-level ones (e.g., MT/V5, middle temporal area) represent motion information differently. However, more recent data from single-cell responses and cortical imaging in macaque indicate that pattern motion signals can be recorded as early as area V1. My thesis addresses whether such signals can be detected in early visual areas in human cortex and considers whether they might arise from feedback processes. Given the large hierarchical distance between them, V1 and MT/V5 have the particularity to be relatively strongly anatomically interconnected. This suggests that V1-MT/V5 coupling might play an important role in motion perception. This idea is supported by a number of studies indicating that MT-to-V1 FB connectivity might play a key role in generating mental representations of perceived motion based on incomplete or illusory sensory input. Interestingly, the relation between these two areas can be investigated through a well-known paradigm of bistable motion which consists of superimposed moving gratings of different orientations that can generate multiple perceptual states over time. These perceptual states appear as spontaneous shifts between the perception of a coherent plaid pattern moving in a single direction and that of a pair of component gratings, transparently sliding over each other in two different directions. Several neurocomputational models have been proposed to explain the neural mechanisms underlying bistable motion perception. In general, they propose that the perception of ambiguous motion signals can be explained by a competition between neural populations that support distinct representations of motion. For example, one hypothesis states that these neural populations are composed of both excitatory and inhibitory units that are involved in both competitive and adaptative mechanisms over time. In my thesis, after designing an efficient bistable moving plaid illusion, we used an event-related fMRI paradigm to study bistable perception dynamics. In preliminary measures, we were able to identify direction-selective voxels in early visuals areas V1, V2 and the hMT+ complex (human motion complex, hMT+, equivalent to MT/V5 in non-human primate and adjacent motion-selective areas). We went on to engineer conditions that would trigger spontaneous perceptual switches while maintaining a constant visual stimulation. The two competitive perceptual states are proposed to consist of two equiprobable and mutually exclusive representations of motion information. While subjects fixated a central cross, to minimize eye movements, they were asked to report their perceptual state. Analyses of the hemodynamic activity in these areas demonstrated that the direction-selective voxels preferentially responded to the perceptual state in accordance with the matching direction. In subsequent analyses, we argue that the results represent neural activity related to the perceptual switching, and are not reflecting eye movement phenomena.Les modèles d'intégration du mouvement sont des candidats idéaux pour examiner la hiérarchie fonctionnelle dans le cortex visuel précoce. L'intégration du mouvement a été largement étudiée et constitue un modèle influent, à l'origine représenté comme un modèle hiérarchique à deux niveaux de type ascendant (ou "feedforward", FF), où les signaux descendants (ou "feedback", FB) ne jouaient aucun rôle apparent dans la perception du mouvement. Dans ce modèle, il est proposé que les aires visuelles de bas niveau détectent et encodent linéairement un mouvement unidimensionnel (ou "composant", par exemple, une alternance simple de bandes noires et blanches se déplaçant orthogonalement à son orientation), tandis que les détecteurs de mouvement de niveau supérieur calculent l'intégration non-linéaire de signaux de mouvement plus complexes (ou "pattern", dans l'exemple précédent, deux composants mobiles superposés et intégrés en un mouvement global). Selon ce point de vue, les aires visuelles de bas niveau (aires visuelles primaires et secondaires, V1 et V2) et celles de plus haut niveau (par exemple, MT/V5, aire temporale médiane) représentent différemment les informations relatives au mouvement. Cependant, des données plus récentes provenant de réponses unicellulaires et d'imagerie corticale chez le macaque indiquent que les signaux de mouvements complexes peuvent être enregistrés dès l'aire V1. Ma thèse vise à déterminer si de tels signaux peuvent être détectés dans les aires visuelles précoces du cortex humain et à examiner s'ils peuvent provenir de processus hiérarchiques de type FB. Compte tenu de la grande distance hiérarchique qui les sépare, V1 et MT/V5 ont la particularité d'être relativement fortement interconnectés anatomiquement. Cela suggère que le couplage V1-MT/V5 pourrait jouer un rôle important dans la perception du mouvement. Cette idée est soutenue par un certain nombre d'études indiquant que la connectivité FB entre MT/V5 et V1 pourrait jouer un rôle clé dans la génération de représentations mentales du mouvement perçu sur la base d'une entrée sensorielle incomplète ou illusoire. Il est intéressant de noter que la relation entre ces deux zones peut être étudiée par le biais d'un paradigme bien connu de mouvement bistable, qui consiste à superposer des grilles composantes mobiles d'orientations différentes pouvant générer plusieurs états perceptifs dans le temps. Ces états perceptifs apparaissent comme des changements spontanés entre la perception d'un motif "plaid" cohérent se déplaçant dans une seule direction et celle d'une paire de grilles composantes, glissant de manière transparente l'une sur l'autre dans deux directions différentes. Plusieurs modèles neurocomputationnels ont été proposés pour expliquer les mécanismes neuronaux qui sous-tendent la perception des mouvements bistables. En général, ils proposent que la perception de signaux de mouvement ambigus puisse être expliquée par une compétition entre des populations neuronales qui supportent des représentations distinctes du mouvement. Par exemple, une hypothèse stipule que ces populations neuronales sont composées d'unités excitatrices et inhibitrices qui sont impliquées dans des mécanismes de compétition et d'adaptation dans le temps. Nous avons ensuite mis au point des conditions permettant de déclencher des transitions de perception spontanées tout en maintenant une stimulation visuelle constante. En théorie, les deux états perceptifs en compétition sont équiprobables et consistent en des représentations mutuellement exclusives du mouvement. Pendant que les sujets fixaient une croix centrale, afin de minimiser les mouvements oculaires, la consigne était d'indiquer leur état perceptif. Les analyses de l'activité hémodynamique dans le cortex visual précoce ont démontré que les voxels sélectifs de la direction répondaient de manière préférentielle à l'état perceptif en fonction de la direction correspondante

Etude des désintégrations de mésons beaux avec photons convertis dans l'expérience LHCb

san