Systèmes d'innovations et dispositifs d'appui pour les agricultures africaines subsahariennes

International audienceLes auteurs analysent les évolutions actuelles des systèmes de production en Afrique, et notamment en zone de savanes d'Afrique de l'Ouest. Ils précisent les caractéristiques de ces innovations en les confrontant avec les théories de l'innovation et présentent les grands déterminants de l'innovation qui marquent ces zones, que ce soit une pression toujours croissante sur les ressources, une ouverture toujours plus marquée vers le marché, ou l'intervention volontaire d'acteurs publics ou privés capables d'impulser des dynamiques de changements. Ils abordent l'évolution des dispositifs d'appui aux producteurs en montrant les limites des approches diffusionnistes et l'émergence de nouvelles manières d'intervenir. Ils proposent une réflexion sur les conditions pour renforcer les processus d'innovation dans un contexte rendu plus difficile qu'autrefois suite au retrait de l'Etat de nombreuses fonctions

Влияние различных агрометеорологических условий на фотосинтез гороха

Рассматривается влияние различных агрометеорологических условий на интенсивность фотосинтеза гороха. Процессы фотосинтеза, дыхания, роста в агрометеорологических расчетах описываются с помощью динамических моделей продукционного процесса растений. Однако все эти модели основаны на аппроксимированных результатах эмпирических исследований, на отдельных территориях по отдельным культурам и предназначены для реализации конкретных целей. Получена количественная оценка влияния солнечной радиации, температуры воздуха, влагообеспеченности, при которых интенсивность фотосинтеза гороха достигает максимальных значений.Розглядається вплив різних агрометеорологічних умов на інтенсивність фотосинтезу гороху. Процеси фотосинтезу, дихання, росту в агрометеорологічних розрахунках описуються за допомогою динамічних моделей продуційного процесу рослин. Проте всі ці моделі засновані на апроксимованих результатах емпіричних досліджень, на окремих територіях по окремих культурах і призначені для реалізації конкретних цілей. Отримана кількісна оцінка впливу сонячної радіації, температури повітря, вологозабезпеченості, при яких інтенсивність фотосинтезу гороху досягає максимальних значень.The influence of the different agro-meteorological conditions on the rate of photosynthesis of pea. Plant development and yield formation - this is a very complex set of a number of physiological processes associated with environmental factors. The processes of photosynthesis, respiration, growth in the agrometeorological calculations are described using dynamic models of the production process of plants. Dynamic models of growth and development of leguminous crops in some way a good description of the specific features of physiological processes in plants. However, all these models are based on the approximate results of empirical research in selected areas for some crops and are designed for specific purposes, so the application of any of them for legume crops need to be very careful . The main processes , which are formed as a result of plant biomass is photosynthesis and respiration. The productivity of photosynthesis is determined by the agrometeorological factors, which are constantly changing during the growing season. At a certain stage of development of the plant photosynthesis productivity per unit area of leaves under given lighting conditions depends on the agro-meteorological conditions, namely the temperature and moisture conditions with the help of numerical experiments determined the effects of different features of agro-meteorological conditions on the rate of photosynthesis . Obtain quantitative estimates of the effect of solar radiation, air temperature, moisture content at which the rate of photosynthesis of pea is highest

Robust error on magnetotelluric impedance estimates

International audienceWe propose here a new, robust, methodology to estimate the errors on a magnetotelluric (MT) impedance tensor. This method is developed with the bounded influence remote-reference processing (BIRRP) code in a single site configuration. The error is estimated by reinjecting an electric field residual obtained after the calculation of an impedance tensor into a tensor function calculation procedure. We show using synthetic examples that the error tensor calculated with our method yields a more reliable error estimate than the one calculated from Jackknife statistics. The modulus of realistic error estimates can be used as a quality control and an accurate inversion constraint of MT surveys. Moreover, reliable error estimates are necessary for new applications of MT to dynamic subsurface processes such as reservoir monitoring

A new era in hydrofluoric acid solution calorimetry: Reduction of required sample size below ten milligrams.

Significant advances have been made in hydrofluoric acid solution calorimetry at Lafayette College in the past 15 years. To determine the degree to which these developments enable the reduction of sample size, calorimetric experiments were performed on hexagonal germanium oxide as a function of sample weight. The resulting calorimetric data indicate that the highest degrees of reproducibility (60.1%) are maintained down to sample sizes of 50 mg, and that precisions of 61%, acceptable for many applications, are observed to sample sizes of 10 mg. Because silicate systems produce weight-based heats of solution that are about twice that of germanium oxide, the required sample size for these will be even less. The new minimum required sample size of 5 to 25 mg (depending on application) is about two orders of magnitude less than that used 20 or 30 years ago. This makes possible many new kinds of projects for HF solution calorimetric investigation, including those on high-pressure materials

The remarkable catalytic activity of the saturated metal organic framework V-MIL-47 in the cyclohexene oxidation

The remarkable catalytic activity of the saturated metal organic framework MIL-47 in the epoxidation of cyclohexene is elucidated by means of both experimental results and theoretical calculations

HardBlare: an efficient hardware-assisted DIFC for non-modified embedded processors

International audienceInformation Flow Control is a security mechanisms that provides security guarantees about information propagation. Other security mechanisms such as access control or cryptography can be used to limit the dissemination of confidential information and the modification of high integrity contents. However, they do not enforce end-to-end properties. They cannot control the dissemination of information once file access is allowed or the data is decrypted. In this context, HardBlare proposes a software/hardware codesign methodology to ensure that security properties are preserved all allong the execution of the system but also during files storage. The general context of HardBlare is to address Dynamic Information Flow Control (DIFC) that generally consists in attaching marks (also known as tags) to denote the type of information that are saved or generated within the system