Strategy for minimizing the uncertainty on concentration-dependent diffusivity as identified by two inverse methods

Models of mass transport in foods do require a large number of parameters, many of which are not available for food materials. Although data on effective diffusivity are abundant in literature, "true" diffusivities applying to the case of molecular diffusion are father scarce. In fact, measurements of molecular diffusivity (D) are not easy in foods and require dedicated devices with multiple cautions. Surprisingly, little concern has been paid to uncertainty accompanying diffusivity coefficients, although crucial. Classically, the unknown D function is identified by minimizing iteratively a merit function that assesses the closeness of the experimental concentration profiles to the simulated ones (method A). A different method compares the mass fluxes to the concentration gradients which bath can be estimated locally from concentration profiles (method B). Advantageously, knowledge about the concentration at the interface and the function linking D to concentration is not a requirement in the method B. The objective of the present study was to identify the requirements for the set of data so to reach a given level of uncertainty on D for both methods (A and B). The number of profiles (time resolution), the number of points per profile (space resolution) and the uncertainty on concentration were basic characteristics of the set of data. Virtual desorption/sorption kinetics were designed in order to compare the estimated value of D with a known reference. The probability density function of D was accessed numerically through the production of m virtual sets of data and applying m times the optimisation procedure. Thus, when the uncertainty on concentration was weak (< 5 %), both methods led to the same accuracy of D. For uncertainties on concentration higher than 5 %, the method B decreased accuracy of D. To increase the accurateness, it was necessary to increase the time and temporal resolution (e.g. error on D was close to the noise intensity if the numbers of concentration profiles or concentration data per profile were higher than 20). If these results were to the advantage of the method A, the weakness of it, was the assessment of the concentration at the interface. (Texte intégral

Foreign direct investment as engine of economic development in peripheral economies. What can we learn from the study of two different cases: the maquiladora subsidiary (Nicaragua) and a textile manufacturing subsidiary in (Albania)

Using the analysis of two apparently very different cases, a Taiwanese maquiladora subsidiary of the garment industry (Nien Hsing Textile Co.) in Nicaragua and an Italian subsidiary in Albania, we try to verify the existence of the benefits attributed by many host governments to inward manufacturing foreign direct investment as engine of development in peripheral economies. In each case, we study three specific questions: (1) the technological transfer from the subsidiary, (2) the mobility potential of the manufacturing activities of the subsidiary, and (3) the evolution of the quality of the subsidiary (integration in the territory and complexity of the activities realised) in time. In answering our questions we conduct fieldwork in the two countries. We interacted directly with stakeholders involved in the operations of each subsidiary including interviews with corporate managers and employees, data collection on subsidiary operations, and visits on production sites. We analyze the main channels of technology transfer focusing on the quality of linkages each subsidiary established in the local economy, on the level of additional formal and informal knowledge benefiting the local labor force, and on the support offered to local suppliers in strengthening production activities. We continue by identifying the main factors affecting the mobility of each subsidiary by differentiating between impeding and facilitating factors. Among impeding factors we concentrate on: (a) the resources (generic vs. specific) utilized by each subsidiary in the two countries, (b) market access opportunities in the local economy, (c) the nature of assets owned and engaged in realizing production activities, and (d) other factors constraining the mobility potential (exit costs and the level of integration of each subsidiary with other units of the multinational enterprise). With regard to facilitating factors we particularly consider the existence of substitute plants. In responding to our third question, we look into the nature of linkages (developmental vs. dependent) established by each subsidiary with local suppliers. Furthermore, we examine not only the change in the level of complexity of functions and duties occurring during the operational life of the subsidiaries but also the specific factors that trigger such a change. Among the factors considered in our research are the decisions made by headquarters on allocation of responsibilities, actions taken by the managers supervising each subsidiary, and on the dynamics occurring in the local business environment. The similarities and differences found in the two cases cast doubts upon the contribution of this investment to the development potential of the economy of the host territory.Postprint (published version

Sign Language Fingerspelling Classification from Depth and Color Images using a Deep Belief Network

Automatic sign language recognition is an open problem that has received a lot of attention recently, not only because of its usefulness to signers, but also due to the numerous applications a sign classifier can have. In this article, we present a new feature extraction technique for hand pose recognition using depth and intensity images captured from a Microsoft Kinect sensor. We applied our technique to American Sign Language fingerspelling classification using a Deep Belief Network, for which our feature extraction technique is tailored. We evaluated our results on a multi-user data set with two scenarios: one with all known users and one with an unseen user. We achieved 99% recall and precision on the first, and 77% recall and 79% precision on the second. Our method is also capable of real-time sign classification and is adaptive to any environment or lightning intensity.Comment: Published in 2014 Canadian Conference on Computer and Robot Visio

On the Convergence of Population Protocols When Population Goes to Infinity

Population protocols have been introduced as a model of sensor networks consisting of very limited mobile agents with no control over their own movement. A population protocol corresponds to a collection of anonymous agents, modeled by finite automata, that interact with one another to carry out computations, by updating their states, using some rules. Their computational power has been investigated under several hypotheses but always when restricted to finite size populations. In particular, predicates stably computable in the original model have been characterized as those definable in Presburger arithmetic. We study mathematically the convergence of population protocols when the size of the population goes to infinity. We do so by giving general results, that we illustrate through the example of a particular population protocol for which we even obtain an asymptotic development. This example shows in particular that these protocols seem to have a rather different computational power when a huge population hypothesis is considered.Comment: Submitted to Applied Mathematics and Computation. 200

JUMPSAT: Qualifying three equipments in one Cubesat mission

We work on a student 3U Cubesat mission, called JUMPSAT, expected for 2017. This is a collaborative project involving both institutions (CNES, ONERA) and schools (ISAE, TELECOM Bretagne). The different equipments to qualify are the Supaero Star Tracker, which measures stars’ luminosity to infer the satellite’s attitude, a detector for particles trapped in the Earth magnetic field designed by the ONERA, and the AOCS. Uplink and Downlink communications will be provided during the mission by the HETE Primary Ground Stations. JUMPSAT is the first Cubesat which needs a three axis attitude control, which involves an innovative mission analysis, to overcome all these constraints. The mission analysis deals with the orbit’s determination, the Cubesat’s structure, the power strategy, and the visibility balance. The particles detector is the only constraint for the altitude of the satellite: we can get meaningful data only at altitudes higher than 700 km. Moreover, the most interesting zones are South Atlantic and poles. But a circular orbit with this altitude does not respect the LOS (French space act).The structure of the Cubesat is also hard to define. To get information from the satellite, we need an antenna, and an attitude and orbital control system to point the antenna at the ground station and the Star Tracker at the stars. Solar Panels cannot be opened out because of the micro elements that could be settled on the particles detector. However, fixed solar panels are not very efficient to recharge batteries. The power balance shows critical problems: both attitude control system and the Star Tracker consume a lot, and cannot work at the same time during the whole orbit. However, all the components are linked: the Star Tracker is not efficient if the satellite attitude is not stabilized; the antenna functioning must be synchronized with visibilities by the ground station. Anyway, the visibility balance stresses the point that a ground station at Toulouse would be particularly welcome. We need also to take into account phenomena of eclipse and satellite drift. To conclude, our mission analysis is deeply constrained by the equipments we want to qualify. Our task is to find the optimal orbit, suggest a power strategy considering the orbital constraints and components’ physical parameters, and to study the visibility balance. It is a real challenge in terms of power consumption, architecture, orbital strategy for such a small satellite

A carboxylesterase, Esterase-6, modulates sensory physiological and behavioral response dynamics to pheromone in Drosophila

Conclusions: Our study presents evidence that Est-6 plays a role in the physiological and behavioral dynamics of sex pheromone response in Drosophila males and supports a role of Est-6 as an odorant-degrading enzyme (ODE) in male antennae. Our results also expand the role of Est-6 in Drosophila biology, from reproduction to olfaction, and highlight the role of ODEs in insect olfaction

Lower deforestation rates in the Brazilian Amazon. Supporting farm forestry

Since 2004, thanks to a monitoring and repression policy, deforestation in the Brazilian Amazon has decreased substantially. If this trend is to continue, smallholder farmers need support to enable them to take advantage of their forest resources and to develop ecologically intensive agricultural systems