The role of the pod in seed development: strategies for manipulating yield

Pods play a key role in encapsulating the developing seeds and protecting them from pests and pathogens. In addition to this protective function, it has been shown that the photosynthetically active pod wall contributes assimilates and nutrients to fuel seed growth. Recent work has revealed that signals originating from the pod may also act to coordinate grain filling and regulate the reallocation of reserves from damaged seeds to those that have retained viability. In this review we consider the evidence that pods can regulate seed growth and maturation, particularly in members of the Brassicaceae family, and explore how the timing and duration of pod development might be manipulated to enhance either the quantity of crop yield or its nutritional properties

Coordinated Path Following for Time-Critical Missions of Multiple UAVs via L1 Adaptive Output Feedback Controllers

This paper develops a complete framework for coordinated control of multiple unmanned air vehicles (UAVs) that are tasked to execute collision-free maneuvers under strict spatial and temporal constraints in restricted airspace. The framework proposed includes strategies for deconflicted real-time path generation, nonlinear path following, and multiple vehicle coordination. Path following relies on the augmentation of existing autopilots with L1 adaptive output feedback control laws to obtain inner-outer loop control structures with guaranteed performance. Multiple vehicle coordination is achieved by enforcing temporal constraints on the speed pro les of the vehicles along their paths in response to information exchanged over a communication network. Again, L1 adaptive control is used to yield an inner-outer loop structure for vehicle coordination. A rigorous proof of stability and performance bounds of the combined path following and coordination strategies is given. Flight test results obtained at Camp Roberts, CA in 2007 demonstrate the benefits of using L1 adaptive control for path following of a single vehicle. Hardware-in-the-loop simulations for two vehicles are discussed and provide a proof of concept for time-critical coordination of multiple vehicles over communication networks with fixed topologies.USSOCOMONR under Contract N00014-05-1-0828AFOSR under Contract No. FA9550-05-1-0157ARO under Contract No. W911NF-06-1-0330EC under Contract 035223-GREX / CECIS

Coordinated Path Following for Time-Critical Missions of Multiple UAVs via L1 Adaptive Output Feedback Controllers

This paper develops a complete framework for coordinated control of multiple unmanned air vehicles (UAVs) that are tasked to execute collision-free maneuvers under strict spatial and temporal constraints in restricted airspace. The framework proposed includes strategies for deconflicted real-time path generation, nonlinear path following, and multiple vehicle coordination. Path following relies on the augmentation of existing autopilots with L1 adaptive output feedback control laws to obtain inner-outer loop control structures with guaranteed performance. Multiple vehicle coordination is achieved by enforcing temporal constraints on the speed pro les of the vehicles along their paths in response to information exchanged over a communication network. Again, L1 adaptive control is used to yield an inner-outer loop structure for vehicle coordination. A rigorous proof of stability and performance bounds of the combined path following and coordination strategies is given. Flight test results obtained at Camp Roberts, CA in 2007 demonstrate the benefits of using L1 adaptive control for path following of a single vehicle. Hardware-in-the-loop simulations for two vehicles are discussed and provide a proof of concept for time-critical coordination of multiple vehicles over communication networks with fixed topologies.USSOCOMONR under Contract N00014-05-1-0828AFOSR under Contract No. FA9550-05-1-0157ARO under Contract No. W911NF-06-1-0330EC under Contract 035223-GREX / CECIS

Tools of the ethylene trade : a chemical kit to influence ethylene responses in plants and its use in agriculture

The simplest unsaturated hydrocarbon, ethylene or ethene, is one of the most widely produced organic chemicals worldwide. It serves as a building block for various materials and chemicals, including plastics, ethanol, detergents, and many more. Strikingly, it also acts as a signaling molecule in virtually all physiological processes and during all developmental stages in plant life. Plant biologists consider ethylene to have a tripartite role in plant development; this gaseous molecule can serve as a plant growth regulator, an aging hormone, and as a stress controller, aiding in defense against both biotic and abiotic stressors. Therefore, the regulation of the ethylene status is indispensable in both agricultural and horticultural practices. Since its discovery as a phytohormone, many chemicals have been developed that are able to affect ethylene responses in plants. Here, an extensive overview of the current toolbox of ethylene regulators, their discovery, function, and applications in both the agri- and horticultural field is presented. Furthermore, possibilities and considerations related to novel small molecules, such as those emerging from the chemical genetics field, are discussed