Science & Mathematics

At the IPAS Conference in 2008, we described in our presentation the idea of a construction kit for micro assembly based on a standardised interface for automatic exchange of (those times mainly) different grippers. In the meantime the construction kit has been developed further and completed purposively. So now automation of a wide range of tasks in the field of micro technology is carried out. At the actual state, the kit is including a miniature modular robot arm, two changing systems, various grippers, suitable storage racks, and additional tools such as cameras and dispensing tips. However the kit is open for everybody to adapt further elements and indeed this is done.

To better understand the hydrodynamics in a Dynamic Filtration module (DF), a local investigation within a complex and confined module named Rotating and Vibrating Filtration (RVF) was scrutinized under laminar flow with viscous Newtonian fluid (Re-mixing = 45). RVF consists of two filtration cells in series, in which a three-blade impeller rotates between two membranes. Particle Image Velocimetry (PIV) measurements were conducted in different operating conditions and synchronized with an optical trigger. In parallel, a simulation approach by Computational Fluid Dynamics (CFD) was developed and compared to PIV. On one hand, PIV measurements indicated that velocity fields and profiles were highly organized and stable within the filtration cell, and mainly governed by the impeller shape. Different feeding flowrate had no significant influence on velocity profile. Considering velocity magnitude, the angular velocity was the dominant contribution compared to radial velocity. However, a particular oscillation of radial velocity component was demonstrated. On the other hand, CFD simulation was in good agreement with PIV regarding on velocity fields and profiles. Results showed that maximum velocity and shear stress appeared at the leading edge of the impeller. A dead-zone (around the surrounding wall of the filtration cell) and a short-cut (close to the central shaft) were confirmed by CFD streamlines under different operating conditions. Moreover, velocity coefficient of the RVF module was 0.31 (mean value) from PIV while 0.35 from CFD, and it was compared to the similar devices in the literature.

It is expected that the agricultural intensification occurred in recent decades in the Argentine Rolling Pampa significantly alters the SOM reserves. Therefore, it is necessary to identify soil organic carbon (C) and nitrogen (N) fractions to understand the functionality and stabilization of these reserves. Our objectives were to study the NT effect in two crop rotations, corn-double cropped wheat/soybean (MWS) and double cropped wheat/soybean (WS) on: 1) SOM and its particle size and biological fractions contents, 2) C and N stubble biomass and 3) some soil properties in order to explain the SOM differences found. The larger biomass residue remaining on the soil surface under NT promoted higher aggregate stability and lower soil temperature and pH. At 0-5 cm soil depth, NT exhibited higher C and N contents, for both uncomplexed and intimately associated to the mineral components fractions. However, the results indicated variations in the SOM protection according to the rotation: in MWS the high aggregate stability showed better physical protection, while in WS the greater cation exchange capacity and the lower value of N released by anaerobic incubation would indicate the presence of transformed SOM. At 5-20 cm soil depth, only in WS, C microbial biomass was higher with a low metabolic rate, indicating again the presence of highly decomposed SOM. The results obtained in WS under NT would indicate the possibility of achieving slower recycled of the SOM.

The performance and operation of the upgraded Yale MP accelerator are described.

The upgrading program for the MP Van de Graaff accelerator at the University of Rochester has been developed with several novel and unique features. We describe the operating experience of the accelerator with particular emphasis on the performance of the cryogenic terminal pumping, the titanium electrode spiral inclined field acceleration tubes, and the overall accelerator transmission and voltage performance with a variety of high current heavy ion beams. The design features of the acceleration tubes are described, and the performance of the tubes is presented with regard to static voltage-holding ability and conditioning procedures, as well as operation with beam. Dependable operation exceeding 12MV on terminal has been achieved. The transmission of the accelerator has been measured for a variety of ion beams up to 197Au. Several charge states of each beam were momentum-analyzed, and the results are compared with predicted stripper yields. The transmission performance with 197Au in the range of 8-10 MV terminal voltage was 30-50 %.

Issu d'une enquête collective de grande ampleur dans les chambres de la famille des tribunaux de grande instance en France, l'article cherche à comprendre pourquoi le domaine de la famille est le terrain privilégié de l'expression d'un souci culturaliste de la part des professionnel-le-s du droit (juges, avocats et greffières) et quels sont les effets, dans la pratique, de ces processus de différenciation des publics sur le traitement des justiciables appartenant aux minorités ethno-raciales. Le concept de racialisation permet de se défaire, au moins provisoirement, d'une posture dénonciatrice à l'encontre des professionnels du droit, en distinguant la mise en oeuvre d'une pragmatique ethnoraciale, de l'expression de représentations racistes disqualifiantes à l'égard des minorités. Nous montrons que les savoirs-juridiques ou psychiatriques-à la disposition des professionnels du droit pour différencier leurs publics selon leur origine sont en pratique moins utilisés que des catégories ethno-raciales profanes. Dans un contexte de justice de masse, ces catégories offrent un moyen rapide de catégoriser les affaires, en appréhendant des situations familiales perçues comme « complexes » dans une opposition binaire et évolutionniste : culture « traditionnelle » et « patriarcale » des minorités ethno-raciales vs culture « moderne » et « émancipatrice » de la population majoritaire. Les catégorisations ethno-raciales qu'opèrent explicitement ou implicitement les professionnel-lees de la justice familiale durcissent ainsi des stéréotypes de genre et de classe présents de manière plus générale dans leur appréhension des affaires familiales.

Contexte : L’obésité pédiatrique est un problème de santé publique mondial, avec des conséquences physiques et psychologiques pour les enfants, mais également pour la société. Objectif : Explorer les freins à la prise en charge du surpoids et de l’obésité de l’enfant par des médecins généralistes (MG) de Savoie et d’Isère non adhérents à un réseau tel que le RéPPOP. Méthode : Étude qualitative, menée par deux investigatrices, ayant conduit à quatorze entretiens semi dirigés auprès de MG installés. Les données verbales ont été enregistrées, transcrites, analysées et triangulées selon une méthode inductive. Résultats : Les MG reconnaissaient l’importance de leur rôle dans la prise en charge de cette pathologie, mais décrivaient plusieurs catégories de freins liés au MG, à l’enfant et sa famille, à la pathologie et à la société. Ils évoquaient des lacunes théoriques et pratiques ainsi qu’un manque de formation. Le manque de temps était aussi soulevé. Les représentations de l’obésité engendraient des comportements d’évitement de la part des MG comme des familles. S’y ajoutaient des difficultés dans la relation médecin-patient, liées à la dimension psycho-sociale de cette pathologie. Enfin, les MG évoquaient des freins liés à la politique de santé et à l’organisation des soins avec un manque de fluidité des filières, une offre de soin parfois limitée et une prise en charge trop tardive. Les MG estimaient que l’obésité pédiatrique était un problème complexe face auquel ils pouvaient ressentir un sentiment d’impuissance. Conclusion : Le renforcement des compétences du MG, la prévention précoce, la prise en charge pluridisciplinaire et la mise en place d’actions gouvernementales spécifiques, permettraient de prévenir l’apparition de l’obésité chez l’enfant, et donc de limiter les difficultés et les échecs de sa prise en charge.

The idea motivating their account, Cappelen and Lepore (C&L) say in (2005), is that semantic content is context invariant, and that all colleagues who take, or even consider, different accounts are just on the wrong track. It is the purpose of their book to disprove all alternative accounts by way of an argument 'by elimination'. The conclusion they arrive at is that their own account must be accepted by everyone as "the only game in town at the end of the day". The present paper is intended to examine this conclusion; its more significant findings are these. Firstly, C&L's account is not, as they suggest, strictly minimalist, but in fact just a moderate version of contextualism. Secondly, prematurely associating semantical incompleteness and context sensitivity, they overlook some possible alternatives to their own view, among them at least one that is attractive. Thirdly, their argument 'by elimination' has an inductive structure, but is inexhaustive, and therefore inconclusive. Fourthly, for several different reasons, their attempts to reject arguments in favour of semantical incompleteness do not work. Finally, their contention that arguments in favour of semantical incompleteness employ metaphysical premisses for semantical conclusions rests on a faulty interpretation of these arguments. In the light of these findings, it is concluded that the central argument of fails.

In Mediterranean-type ecosystems, water availability is one of the most significant variables that regulates whole plant leaf area. An equilibrium should exist between climate, soil and leaf area in such water-limited conditions. The aim of this study was to identify the relations between leaf area index (LAI), environment (climate, soil) and fluxes (water, carbon) in Mediterranean evergreen oak (Quercus ilex L.) ecosystems. To achieve this objective, 50-years simulations were performed using the FOREST-BGC model by varying LAI for a reference site and for different climates and soil water holding capacities (SWC). Transpiration, drought stress, net photosynthesis and canopy water use efficiency (WUE) were examined on a yearly basis for the last ten years of the simulation. Similar to other findings, our results show that LAI depends on site water availability, including both climate (precipitation, potential evapotranspiration) and soil factors (e.g. water storage capacity). Low SWC limit the development of the ecosystem. On high SWC soils, development is mainly limited by the climate. When LAI increases under constant SWC and climate conditions, the decrease in annual transpiration per unit of LAI is accompanied by an increase in drought stress. Equilibrium LAI maximizes carbon assimilation. For the reference site, the equilibrium LAI is close to the observed value, 3.25. The corresponding transpiration, assimilation and WUE are 375 mm, 1251 g C m$^{-2}$ and 3.1 mmol CO$_2$ mol$^{-1}$ H$_2$O, respectively. For the different sites, there is an hyperbolic decline of WUE with increasing SWC. This implies that production efficiency per unit leaf area is higher in most water-limited environments. Our study shows that a model such as FOREST-BGC allows inter-relations between water balance, carbon balance and drought stress to be taken into account to better understand ecosystem LAI.

Microclimate and tree age have been suggested to be factors influencing the defense capacity against oxidative stress. Therefore, 5-year-old Fagus sylvatica seedlings were grown on a scaffolding in the sun and shade crown of 55-year-old trees throughout one growing season. Independent of tree age sun leaves had a lower specific leaf area, lower pigment contents and a more capacitive antioxidative system than shade leaves. In addition, in the sun crown leaves of seedlings displayed a higher specific leaf area than leaves of adult trees. Age dependent changes in leaf morphology were related to changes in the defense capacity against oxidative stress, with area based concentrations of antioxidants and pigments increasing with tree age. Thus our results suggest that differences in the response to oxidative stress may be attributed to age and crown position related differences in the specific leaf area, the latter influencing the biochemical and physiological performance of Fagus sylvatica leaves.

Context: While sub-micron- and micron-sized dust grains are generally well mixed with the gas phase in protoplanetary disks, larger grains will be partially decoupled and as a consequence have a different distribution from that of the gas. This has ramifications for predictions of the observability of protoplanetary disks, for which gas-only studies will provide an inaccurate picture. Specifically, criteria for gap opening in the presence of a planet have generally been studied for the gas phase, whereas the situation can be quite different in the dust layer once grains reach mm sizes, which is what will be observed by ALMA. Aims: We aim to investigate the formation and structure of a planetary gap in the dust layer of a protoplanetary disk with an embedded planet. Methods: We perform 3D, gas+dust SPH simulations of a protoplanetary disk with a planet on a fixed circular orbit at 40 AU to study the evolution of both the gas and dust distributions and densities in the disk. We run a series of simulations in which the planet mass and the dust grain size varies. Results: We show that the gap in the dust layer is more striking than in the gas phase and that it is deeper and wider for more massive planets as well as for larger grains. For a massive enough planet, we note that cm-sized grains remain inside the gap in corotation and that their population in the outer disk shows an asymmetric structure, a signature of disk-planet interactions even for a circular planetary orbit, which should be observable with ALMA.

Les acides gras polyinsaturés à longue chaîne (AGPI-LC) de la série n-3 jouent un rôle essentiel dans le fonctionnement cérébral, notamment dans le maintien des processus de plasticité synaptique et de mémoire au cours du vieillissement. Il est maintenant bien admis que ces acides gras peuvent moduler la transcription de gènes impliqués dans les processus de plasticité synaptique sous-tendant les performances mnésiques via leur liaison à des récepteurs nucléaires tels que les PPAR (peroxisome proliferator-activated receptor) et les RXR (retinoid X receptor). Les RXR sont les partenaires communs d’hétérodimérisation de nombreux autres récepteurs, dont le récepteur nucléaire de l’acide rétinoïque (AR), RAR (retinoic acid receptor), métabolite actif de la vitamine A. Ainsi, les RXR jouent un rôle majeur dans la régulation des voies de signalisation des AGPI n-3 et des rétinoïdes.Dans ce contexte, l’objectif de notre travail était de mieux comprendre les mécanismes mis en jeu dans l’action des AGPI-LC n-3 sur les processus neurobiologiques qui sous-tendent les performances mnésiques au cours du vieillissement, notamment en abordant de manière spécifique les mécanismes mis en jeu dans les interactions entre les voies de signalisation des AGPI-LC n-3 et des rétinoïdes. Les approches expérimentales mises en place ont consisté notamment à évaluer chez le rat âgé les effets de supplémentations nutritionnelles en AGPI-LC n-3 et/ou vitamine A sur les performances de mémoire, ainsi que l’action du DHA administré seul sur différents types de mémoire dépendants de l’hippocampe.Nos principaux résultats montrent une altération du métabolisme des acides gras et de la vitamine A au cours du vieillissement. Ces changements métaboliques sont associés à une hypoexpression des voies de signalisation des AGPI n-3 et des rétinoïdes, accompagnée de déficits mnésiques. Nous montrons par ailleurs un effet synergique d’une supplémentation nutritionnelle en AGPI-LC n-3 et en vitamine A sur le maintien des performances de mémoire chez l’animal âgé. De plus, cette supplémentation permet de prévenir, dans l’hippocampe, les changements de composition en AGPI n-3 ainsi que l’hypoexpression des ARNm de RXRγ et de kinases régulées par l’AR et les AGPI n-3.Ces résultats plaident en faveur d’une action synergique des AGPI-LC n-3 et de la vitamine A sur le maintien des performances mnésiques au cours du vieillissement, via une action combinée sur leurs voies de signalisation, lesquelles participeraient ainsi au maintien de certains processus de plasticité synaptique sous-tendant la mémoire et qui se trouvent être altérés avec l’âge.