Science & Mathematics

Anomalies in climatic behavior is threatening various aspects of life including environmental degradation, food insecurity, and widespread of diseases. The continual build-up of atmospheric carbon dioxide (CO2) and other malpractices are among the factors responsible for ecosystem degradation. Field experimentation was conducted, where stratified random sampling was employed to delineate point were Phoenix dactylifera and Mangifera indica was sampled. Experimental point was replicated twice where moist soil was examined for its organic matter and organic carbon content, before and after the experiment. The textural class of the area using USDA textural model after laboratory analysis indicated soils of University of Abuja, Federal Capital Territory of Nigeria ranging from loam to sandy-loam soils. Laboratory fractionalization indicated that the soils of the area has coarse sand value (1.8 g kg-1), fine sand content ranging from (4.5 – 5.2 g kg-1), silt content at (4.5 – 5.2g kg-1) and clay content at (72 g kg-1). Estimation analysis revealed that the organic matter and organic carbon content of the area is low to moderately low. Results of the study revealed that Phoenix dactylifera and Mangifera indica was able to sequester carbon in the form of CO2 which was audited in the form of soil organic carbon (SOC). The study thereby encourages the cultivation of Phoenix dactylifera and Mangifera indica which is not onlyeconomic trees that produce food or fuelwood, but as a climate change tool that could be used to regulate climate change in the form of CO2 sequestration.

The identification and evaluation of trigger mechanisms for volcano flank instabilities and/or collapse represent a key issue for risk assessment in densely populated volcanic areas, as well as in long-distance settings, particularly in case of island or coastal volcanoes. Here we address quantitatively the effects of external (seismic) and inner (magmatic) forcing on the stress-strain state associated to flank instabilities at Mount Etna (Sicily, southern Italy) by means of a 2-D finite difference method numerical modeling. Modeled seismic actions include strong near-field, strong far-field, and low-magnitude near-field earthquakes. Magmatic actions consider the inner pressure changes induced by energetic lava fountains in the summit crater area and subvertical and oblique dike ascent below the summit area. Model results are validated in light of available monitoring data and recent eruptive activity. Numerical results show that the main strain effects are produced by high-magnitude near-field earthquakes (expected return time of ~103 yrs) and by vertical uprise of a magma dike below the volcano summit area. Maximum displacements in the order of tens of centimeters may involve the summit area, up to some 106 m3/m over some kilometers laterally. Stress releases up to 107 Pa may affect a limited portion of the magmatic conduit, thus favoring major effusive flank eruptions. Major catastrophic events, such as volcano flank collapse, should not be expected by applying, either individually or combined, the aforementioned actions.

Cette thèse a pour objet de répondre à la question suivante : un choix de service public est-il compatible avec un choix d’ordre financier, car faisant intervenir des critères financiers, parmi lesquels celui de rentabilité financière ? Elle se situe dans un contexte de profondes mutations du secteur public. Prenant comme cadre théorique le New Public Management, constatant une appropriation par le droit administratif des notions d’intérêt financier et de rentabilité, cette recherche exploratoire se poursuit par des entretiens auprès d’élus et d’administratifs de 26 communes. Elle montre un poids des critères financiers proche de celui des critères de service public et un net intérêt porté à un outil de calcul de rentabilité financière, répondant là positivement à la question. Elle démontre également que les administratifs jouent un véritable rôle d’experts financiers. Enfin elle laisse entrevoir qu’élus et administratifs pourraient exercer un micro-pouvoir sur les spécialistes français du management public et les personnalités politiques, adhérant plutôt à l’idée d’incompatibilité d’un choix de service public et de la notion de rentabilité financière.

In the present study, the heterogeneous conversion of nitrogen oxide (NO) and nitrogen dioxide (NO2) was studied at atmospheric humidity levels on flame soot surfaces treated with gaseous nitric acid (HNO3). In addition, the heterogeneous reaction of HNO3 on soot was investigated at atmospheric humidity. For the treatment of soot by pure HNO3 only reversible uptake with a surface coverage of ~1-2x1014 HNO3 cm-2 was observed for HNO3 mixing ratios in the range 250-800ppbv. Only for higher HNO3 mixing ratios of >800ppbv the formation of NO and NO2 was observed. The results were not affected by the addition of NO. In none of the experiments with HNO3 the formation of nitrous acid (HONO) was observed. For HNO3 mixing ratios

This article aims at showing how consideration of architectural and hydraulic features of root systems can help in the understanding of water uptake by plants. Relevant data on architecture and hydraulics of roots can be brought together in the ’Hydraulic Tree Model’ of the root system, a model that couples a root system architecture model and laws for water flow to and into roots. In this way, a detailed portrait of water absorption is given, from the single root to the whole root system. Two contrasting plants, maize and peach tree, illustrate model applications and results. These plants not only differ in architectural features, but also in the distribution of hydraulic conductance in the root system. Maize uptake pattern is highly heterogeneous, showing patches of high absorption rates distributed throughout the root system. In contrast, the peach tree is characterized by a localized uptake in the upper, proximal part of the root system. (© Inra/Elsevier, Paris.)

Background: Daily activities have been associated with neurocognitive performance. However, much of this research has used in-person neuropsychological testing that requires participants to travel to a laboratory or clinic, which may not always be feasible and does not allow for the examination of real-time relationships between cognition and behavior. Thus, there is a need to understand the real-time relationship between activities in the real world and neurocognitive functioning to improve tracking of symptoms or disease states and aid in the early identification of neurocognitive deficits among at-risk individuals. Objective: We used a smartphone-based ecological momentary cognitive assessment (EMCA) platform to examine real-time relationships between daily activities and neurocognitive performance (executive functioning and verbal learning) in the everyday environment of middle-aged and older adults with and without HIV. Methods: A total of 103 adults aged 50-74 years (67 persons with HIV; mean age 59 years, SD 6.4) were recruited from the University of California, San Diego HIV Neurobehavioral Research Program and the San Diego community. Participants completed our EMCA protocol for 14 days. Participants reported their current daily activities 4 times per day; following 2 of the 4 daily ecological momentary assessment (EMA) surveys, participants were administered the mobile Color-Word Interference Test (mCWIT) and mobile Verbal Learning Test (mVLT), each once per day. Activities were categorized into cognitively stimulating activities, passive leisure activities, and instrumental activities of daily living (IADLs). We used multilevel modeling to examine the same-survey and lagged within-person and between-person effects of each activity type on mobile cognitive performance. Results: On average, participants completed 91% of the EMA surveys, 85% of the mCWIT trials, and 80% of the mVLT trials, and they reported engaging in cognitively stimulating activities on 17% of surveys, passive leisure activities on 33% of surveys, and IADLs on 20% of surveys. Adherence and activity percentages did not differ by HIV status. Within-persons, engagement in cognitively stimulating activities was associated with better mCWIT performance (β=-1.12; P=.007), whereas engagement in passive leisure activities was associated with worse mCWIT performance (β=.94; P=.005). There were no lagged associations. At the aggregate between-person level, a greater percentage of time spent in cognitively stimulating activities was associated with better mean mVLT performance (β=.07; P=.02), whereas a greater percentage of time spent in passive leisure activities was associated with worse mean mVLT performance (β=-.07; P=.01). IADLs were not associated with mCWIT or mVLT performance. Conclusions: Smartphones present unique opportunities for assessing neurocognitive performance and behavior in middle-aged and older adults' own environment. Measurement of cognition and daily functioning outside of clinical settings may generate novel insights on the dynamic association of daily behaviors and neurocognitive performance and may add new dimensions to understanding the complexity of human behavior.

This paper shows that most of the so far identified constituents of the tropospheric organic particulate matter belong to a semivolatile fraction for which gas phase diffusion in the lower troposphere is sufficiently fast to establish thermodynamic equilibrium between aerosol particles. For the first time analytical expressions for this process are derived. Inspection of vapor pressure data of a series of organic substances allows a rough estimate for which substances this mixing process must be considered. As general benchmarks we conclude that for typical aerosol radii between 0.1 and 1 µm this mixing process is efficient at 25°C for polar species with molecular weights up to 200 and for non-polar species up to 320. At ?10°C, these values are shifted to 150 for polar and to 270 for non-polar substances. The extent of mixing of this semivolatile fraction is governed by equilibrium thermodynamics, leading to a selectively, though not completely, internally mixed aerosol. The internal mixing leads to a systematic depression of melting and deliquescence points of organic and mixed organic/inorganic aerosols, thus leading to an aerosol population in the lower troposphere which is predominantly liquid.

Algeria is seeking to achieve sustainable agricultural development due to its increasing effects in providing the growing food needs of the population and providing job opportunities for current and future generations. .The agricultural sector is the main source of food and also contributes to providing inputs for many industries that depend mainly on agricultural products. It is also a source of hard currency through its ability to achieve a surplus for export, in addition to creating new job opportunities through various projects.The aim of this study is to introduce the state of Oued Souf is rich in natural, human and water resources. It is especially known for producing some agricultural crops such as potatoes, wheat, barley, peanuts and more. It also aims at identifying the most important challenges it faces so that we can suggest a number of recommendations that contribute to addressing these challenges.

Le gaspillage alimentaire est un phénomène important puisque 1/3 de la production mondiale est gaspillé chaque année. Même si de plus en plus de campagnes de sensibilisation se développent autour de cette thématique, les aliments non consommés finissent généralement dans nos poubelles en tant que biodéchets. Les politiques actuelles tentent de mettre en place des moyens pour les limiter et améliorer leur utilisation. En effet, devant l’augmentation du volume de nos poubelles, il devient important de séparer à la source et de valoriser ces déchets organiques possédant encore un potentiel important. Ainsi, des voies de valorisation ont été étudiées à travers le monde puis adaptées et mises en place à l’échelle d’un des maillons de la chaîne alimentaire : les grandes surfaces, ceci au niveau du bassin rennais. Ce qui caractérise ce gisement particulier c’est les volumes importants, la présence de beaucoup d’emballages plastiques et la variabilité en type de produits. L’étude d’initiatives innovantes utilisées dans différents pays a permis de dégager différentes voies de valorisation possible : pour l’alimentation humaine (grâce à la transformation), pour l’alimentation animale, puis pour générer des matières premières (molécules d’intérêt, compostage) et de l’énergie (biofuels, méthanisation). Leur adaptation au gisement de produits invendus des supermarchés a permis de soulever des difficultés de mises en place concrètes et des besoins de connaissances sur lesquels il faut agir pour permettre le développement de telles voies de valorisation. Une meilleure connaissance des volumes et des types de gisements, l’importance de mettre en relation les différents acteurs du territoire, le rôle de la réglementation, ou encore la sensibilisation des ménages, sont autant de critères à prendre en compte pour améliorer l’utilisation des produits issus du gaspillage.

In order to accurately examine structures surfaces, it is interesting to use surface SAW (Surface Acoustic Wave). Such waves are well suited for example to detect early emerging cracks or to test the quality of a coating. In addition, when coatings are thin or when emergent cracks are precocious, it is necessary to excite surface waves beyond 10MHz. Finally, when structures are not flat, it makes sense to have flexible or conformable sensors for their characterization. To address this problem, we propose to develop SAW type of interdigital sensors (or IDT for InterDigital Transducer), based on flexible piezoelectric plates. Initially, in order to optimize these sensors, we modeled the behavior of these sensors and identified the optimum characteristic sizes. In particular, the thickness of the piezoelectric plate and the width of the interdigital electrodes have been studied. Secondly, we made composites based on barium titanate foams in order to have flexible piezoelectric plates and to carry out thereafter sensors. Then, we studied several techniques in order to optimize the interdigitated electrodes deposition on this type of material. One of the difficulties concerns the fineness of these electrodes because the ratio between the length (typically several millimeters) and the width (a few tens of micrometers) of electrodes is very high. Finally, mechanical, electrical and acoustical characterizations of the sensors deposited on aluminum substrates were able to show the quality of our achievement.