Nitrogen deficiency impacts on leaf cell and tissue structure with consequences for senescence associated processes in Brassica napus

International audienceImprovement of nutrient use efficiency is a major goal for several crop plants, especially Brassica napus. Indeed, the low nitrogen use efficiency (NUE) in this crop results in negative economic and ecological consequences. The low NUE of oilseed rape is mainly due to low remobilization of nitrogen from vegetative parts to growing organs. Remobilization of leaf nitrogen takes place during senescence, a process known to strongly modify cell and tissue structure. This study focused on the impact of moderate N depletion, expected to induce 30% reduction of seed yield, on these structural modifications. Two genotypes (Aviso and Express) were studied, with different tolerance of nitrogen depletion, evaluated through seed yield and dry mass production. Structural modifications of leaf cells and tissues were investigated through NMR relaxometry and light microscopy. Lower tolerance of N depletion was associated with higher impact on senescence associated structural modification pattern. The link between leaf structure modifications and nutrient remobilization is discussed. It is proposed that leaf structure monitoring during senescence through NMR device could be developed to select genotypes with high NUE

Baseline data of four insecticides with different modes of action for Anastrepha fraterculus and Ceratitis capitata (Diptera: Tephritidae)

La mosca de la fruta del Mediterráneo, Ceratitis capitata (Wiedemann), y la mosca sudamericana de los frutos, Anastrepha fraterculus (Wiedemann) son plagas de gran importancia económica en Argentina y el mundo. Una de las formas de control es el uso de insecticidas en pulverizaciones totales o en cebos. El uso reiterado de un determinado producto ejerce una fuerte presión de selección, pudiendo ocasionar la aparición de resistencia. El objetivo de este trabajo fue determinar el dato de nivel básico de cuatro insecticidas con diferentes mecanismos de acción mediante bioensayos en laboratorio. Los productos utilizados fueron formulaciones comerciales de ciantraniliprol, clorpirifos, lambdacialotrina y spinosad. La concentración letal media se estimó mediante un análisis de la curva dosis-respuesta. Para ciantraniliprol y clorpirifós los machos y las hembras de ambas especies fueron igualmente susceptibles. Para lambdacialotrina se detectaron diferencias entre las dos especies; la CL50 de A. fraterculus (0,058 y 0,074 para machos y hembras respectivamente) fue menor que la de C. capitata (0,523 y 0,624 para machos y hembras respectivamente). Para spinosad, los machos de A. fraterculus fueron igualmente susceptibles que los machos y las hembras de C. capitata. Estos resultados generan valores de referencia para Argentina y evidencian la necesidad de completar este tipo de estudios con evaluaciones de poblaciones naturales sobre las cuales se ejerce control químico así como con ensayos en campo y semi-campo. Asimismo muestran la necesidad de completar este tipo de estudios con evaluaciones de los niveles de ingesta en las distintas concentraciones.The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), and the South American fruit fly, Anastrepha fraterculus (Wiedemann) are pests of major economic importance in Argentina and worldwide. One way to control them is the use of insecticide in sprays or baits. The repeated use of a particular product exerts a strong selection pressure and can lead to development of resistance. The aim of this study was to determine baseline data of four insecticides with different mechanisms of action through laboratory bioassays. The products used were commercial formulations of cyantraniliprole, chlorpyrifos, lambdacyalothrin and spinosad. The mean lethal concentration was estimated by a dose-response curve analysis. Cyantraniliprole and chlorpyrifos were equally susceptible for males and females of both species. For lambdacyalothrin differences between the two species were detected; LC50 of A. fraterculus (0.058 and 0.074 for males and females respectively) was lower than that of C. capitata (0.523 and 0.624 for males and females respectively). For spinosad, A. fraterculus males were equally susceptible than males and females of C. capitata. These results generate reference values for Argentina and demonstrate the need to complete these studies with field evaluations of natural populations on which chemical control is exercised as well as with field and semi-field trials. It also shows the need to complete these studies in which the intake at different concentrations is measured.Fil: Paez Jerez, P. G.. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia. Cátedra. Terapéutica Vegetal; ArgentinaFil: Carrizo, B. N.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Tucumán-Santiago del Estero. Estación Experimental Agropecuaria Famaillá; ArgentinaFil: Musse, R.. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia. Cátedra. Terapéutica Vegetal; ArgentinaFil: Varela, E.. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia. Cátedra. Terapéutica Vegetal; ArgentinaFil: Armiñana, A.. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia. Cátedra. Terapéutica Vegetal; ArgentinaFil: Milla, F.. Instituto Nacional de Tecnología Agropecuaria. Centro Nacional de Investigaciones Agropecuarias. Centro de Investigación de Ciencias Veterinarias y Agronómicas. Instituto de Genética; ArgentinaFil: Vera, Maria Teresa. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia. Cátedra. Terapéutica Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: de la Vega, M. H.. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia. Cátedra. Terapéutica Vegetal; Argentin

Modeling, Evaluation, and Scale on Artificial Pedestrians: A Literature Review

Modeling pedestrian dynamics and their implementation in a computer are challenging and important issues in the knowledge areas of transportation and computer simulation. The aim of this article is to provide a bibliographic outlook so that the reader may have quick access to the most relevant works related to this problem. We have used three main axes to organize the article's contents: pedestrian models, validation techniques, and multiscale approaches. The backbone of this work is the classification of existing pedestrian models; we have organized the works in the literature under five categories, according to the techniques used for implementing the operational level in each pedestrian model. Then the main existing validation methods, oriented to evaluate the behavioral quality of the simulation systems, are reviewed. Furthermore, we review the key issues that arise when facing multiscale pedestrian modeling, where we first focus on the behavioral scale (combinations of micro and macro pedestrian models) and second on the scale size (from individuals to crowds). The article begins by introducing the main characteristics of walking dynamics and its analysis tools and concludes with a discussion about the contributions that different knowledge fields can make in the near future to this exciting area

New consumer load prototype for electricity theft monitoring

Illegal connection which is direct connection to the distribution feeder and tampering of energy meter has been identified as a major process through which nefarious consumers steal electricity on low voltage distribution system. This has contributed enormously to the revenue losses incurred by the power and energy providers. A Consumer Load Prototype (CLP) is constructed and proposed in this study in order to understand the best possible pattern through which the stealing process is effected in real life power consumption. The construction of consumer load prototype will facilitate real time simulation and data collection for the monitoring and detection of electricity theft on low voltage distribution system. The prototype involves electrical design and construction of consumer loads with application of various standard regulations from Institution of Engineering and Technology (IET), formerly known as Institution of Electrical Engineers (IEE). LABVIEW platform was used for data acquisition and the data shows a good representation of the connected loads. The prototype will assist researchers and power utilities, currently facing challenges in getting real time data for the study and monitoring of electricity theft. The simulation of electricity theft in real time is one of the contributions of this prototype. Similarly, the power and energy community including students will appreciate the practical approach which the prototype provides for real time information rather than software simulation which has hitherto been used in the study of electricity theft

Traffic aware wireless sensor networks MAC protocol for smart grid applications using spiral backoff mechanism

Smart grid is an innovative electrical power delivery networks which integrate distributed renewable energy sources and electric vehicles with the main power grid. Smart grid employs communication network to automate the generation, transmission and distribution and collect metering information from different parts of the grid and the customers to optimize energy distribution and consumption. Moreover, Distribution automation, Demand-Response (DR) and Direct Load Control (DLC) are applied to reduce the consumption of electricity during peak hours. However, it requires a robust, reliable communication network to facilitate real time data exchange between the utility gateway and smart meters of the customer premises. IEEE 802.15.4 standard provides a low cost, low power WSNs solution for smart grid communication networks. The IEEE 802.15.4 standard uses slotted Carrier Sense Multiple Access-Collision Avoidance (CSMA-CA) with binary exponential backoff algorithm (BEB) to avoid collision between the sensor nodes. However, BEB does not consider the s requirement which degrade the smart grid network performance. In this paper, a traffic aware spiral backoff mechanism is proposed to improve the network performance. Simulation results show that proposed spiral backoff algorithm reduces the end-to-end delay and increase packet delivery ratio (PDR) for real time data

Recuperação Avançada de Petróleo

Um dos objetivos desse trabalho é analisar as potencialidades, características e evolução das competências tecnológicas, traduzidas através de dados estatísticos de patentes, no que se refere aos métodos de recuperação avançada de petróleo (“Enhanced Oil Recovery” - EOR). Para tanto, serão apresentados os resultados empíricos obtidos relacionando, sempre que possível, com aspectos econômicos, políticos, e tecnológicos da indústria do petróleo