Drones: Innovative Technology for Use in Precision Pest Management.

Arthropod pest outbreaks are unpredictable and not uniformly distributed within fields. Early outbreak detection and treatment application are inherent to effective pest management, allowing management decisions to be implemented before pests are well-established and crop losses accrue. Pest monitoring is time-consuming and may be hampered by lack of reliable or cost-effective sampling techniques. Thus, we argue that an important research challenge associated with enhanced sustainability of pest management in modern agriculture is developing and promoting improved crop monitoring procedures. Biotic stress, such as herbivory by arthropod pests, elicits physiological defense responses in plants, leading to changes in leaf reflectance. Advanced imaging technologies can detect such changes, and can, therefore, be used as noninvasive crop monitoring methods. Furthermore, novel methods of treatment precision application are required. Both sensing and actuation technologies can be mounted on equipment moving through fields (e.g., irrigation equipment), on (un)manned driving vehicles, and on small drones. In this review, we focus specifically on use of small unmanned aerial robots, or small drones, in agricultural systems. Acquired and processed canopy reflectance data obtained with sensing drones could potentially be transmitted as a digital map to guide a second type of drone, actuation drones, to deliver solutions to the identified pest hotspots, such as precision releases of natural enemies and/or precision-sprays of pesticides. We emphasize how sustainable pest management in 21st-century agriculture will depend heavily on novel technologies, and how this trend will lead to a growing need for multi-disciplinary research collaborations between agronomists, ecologists, software programmers, and engineers

Mechanical characterization of elastoplastic materials - use of axisymetric indenters

Dans cet article, nous présentons une expression de la courbe d'indentation instrumentée d'un matériau élastoplastique pouvant s'écrouir. Cette expression nécessite d'expliciter la pression moyenne de contact entre l'indenteur et le matériau, ainsi que de tenir compte de la forme que prend la surface du matériau sous l'indenteur. Le cas d'un indenteur conique est d'abord étudié ; puis l'expression est généralisée aux indenteurs d'autres formes (supposés axisymétriques). Les résultats sont comparés aux modèles déjà existants.In this article, an expression of the depth-sensing indentation curve for strain-hardening materials is introduced. This expression requires to formulate the mean contact pressure between the indenter and the material and to account for the shape of the material surface under the indenter. The case of a conical indenter is first studied, and extended to other axisymetric indenters. Results are compared to previous models

Mechanical characterization of elastoplastic materials - use of axisymetric indenters

Dans cet article, nous présentons une expression de la courbe d'indentation instrumentée d'un matériau élastoplastique pouvant s'écrouir. Cette expression nécessite d'expliciter la pression moyenne de contact entre l'indenteur et le matériau, ainsi que de tenir compte de la forme que prend la surface du matériau sous l'indenteur. Le cas d'un indenteur conique est d'abord étudié ; puis l'expression est généralisée aux indenteurs d'autres formes (supposés axisymétriques). Les résultats sont comparés aux modèles déjà existants.In this article, an expression of the depth-sensing indentation curve for strain-hardening materials is introduced. This expression requires to formulate the mean contact pressure between the indenter and the material and to account for the shape of the material surface under the indenter. The case of a conical indenter is first studied, and extended to other axisymetric indenters. Results are compared to previous models

Influence de la teneur de nickel sur le comportement tribologique et électrochimique de l’alliage TiNi.

Parmi les matériaux métalliques, les alliages de TiNi sont employés principalement pour des applications biomédicales et/ou dentaires dues à leur meilleure compatibilité mécanique avec les tissus, leur module de Young proche de celui de l’os et une résistance élevée à la corrosion dans les fluides du corps et une bonne biocompatibilité. Pour cette raison, le comportement à la corrosion et à l’usure de l’alliage TiNi avec des teneurs en Ni varie de 40 à 60% en poids, ont été étudiés afin de vérifier l’effet du Ni sur la biocompatibilité de cet alliage pour des applications dentaires

Hardness Evaluation of Porous Hydroxyapatite Coating

The extensive use of appropriate coatings to improve wear resistance, friction coefficient, electrical properties, corrosion resistance and biomedical application has stimulated a growing interest in their mechanical properties and especially hardness testing that is routinely used for coating evaluation. In this study Jönsson and Hogmark model is applied for the porous hydroxyapatite produced by plasma spraying on Ti6A14V substrate. Firstly, the effect of indentation load on hardness values of coating and substrate are studied. The modified Jönsson and Hogmark model is used to explain the composite hardness behavior and the effect of coating porosity

Requirements for translation re-initiation in Escherichia coli: roles of initiator tRNA and initiation factors IF2 and IF3

Despite its importance in post-transcriptional regulation of polycistronic operons in Escherichia coli, little is known about the mechanism of translation re-initiation, which occurs when the same ribosome used to translate an upstream open reading frame (ORF) also translates a downstream ORF. To investigate translation re-initiation in Escherichia coli, we constructed a di-cistronic reporter in which a firefly luciferase gene was linked to a chloramphenicol acetyltransferase gene using a segment of the translationally coupled geneV–geneVII intercistronic region from M13 phage. With this reporter and mutant initiator tRNAs, we show that two of the unique properties of E. coli initiator tRNA – formylation of the amino acid attached to the tRNA and binding of the tRNA to the ribosomal P-site – are as important for re-initiation as for de novo initiation. Overexpression of IF2 or increasing the affinity of mutant initiator tRNA for IF2 enhanced re-initiation efficiency, suggesting that IF2 is required for efficient re-initiation. In contrast, overexpression of IF3 led to a marked decrease in re-initiation efficiency, suggesting that a 30S ribosome and not a 70S ribosome is used for translation re-initiation. Strikingly, overexpression of IF3 also blocked E. coli from acting as a host for propagation of M13 phage