1,034 research outputs found

    Northern Range Extensions for Caprella scaura Templeton, 1836 (Crustacea: Amphipoda: Caprellidae) on the Florida Gulf Coast and in South Carolina

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    Previous northwestern Atlantic records for the caprellid amphipod Caprella scaura Templeton, 1836 were confined to St. Croix (US Virgin Islands), St. Barthélemy, and Puerto Rico, islands bordering the northern Caribbean Sea. Based on recent collections, C. scaura is now reported from the Gulf of Mexico (St. Andrew Bay, Florida) and the US east coast (Charleston Harbor, South Carolina). These constitute the first records for this apparently non-indigenous species in waters of the continental eastern United States, establishing considerable northern range extensions for C. scaura in the northwest Atlantic

    Aphid Feeding Behavior: Relationship to Barley Yellow Dwarf Virus Resistance in \u3ci\u3eAgropyron\u3c/i\u3e Species

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    The infectibility of various Agropyron species (wheatgrasses) was examined with respect to three isotates of barley yellow dwarf virus (BYDV) by infesting them with appropriate vector aphids, followed by testing by enzyme-linked immunosorbent assay. Feeding behavior of the vetors Rhopalosiphum padi and Sitobion avenae was also electronically monitored to determine their ability to inoculate phloem. The results indicated that resistance to BYDV infection occurs in several Agropyron species. For most species tested. resistance seemed due to failure in virus increase. but in some species a major constraint on infection \\\u27as the inability of vectors to locate phloem. Two potential approaches to breeding for reduced BYDV in wheat by crossing with Agropyron species may thus be: incorporating factors reducing or preventing virus production and incorporating factors reducing the ability of vectors to inoculate plants successfully

    Aircraft Loss of Control: Problem Analysis for the Development and Validation of Technology Solutions

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    Aircraft loss of control (LOC) is a leading cause of fatal accidents across all transport airplane and operational classes. LOC can result from a wide spectrum of precursors (or hazards), often occurring in combination. Technologies developed for LOC prevention and recovery must therefore be effective under a wide variety of conditions and uncertainties, including multiple hazards, and the validation process must provide a means of assessing system effectiveness and coverage of these hazards. This paper provides a detailed description of a methodology for analyzing LOC as a dynamics and control problem for the purpose of developing effective technology solutions. The paper includes a definition of LOC based on several recent publications, a detailed description of a refined LOC accident analysis process that is illustrated via selected example cases, and a description of planned follow-on activities for identifying future potential LOC risks and the development of LOC test scenarios. Some preliminary considerations for LOC of Unmanned Aircraft Systems (UAS) and for their safe integration into the National Airspace System (NAS) are also discussed

    Preliminary Analysis of Aircraft Loss of Control Accidents: Worst Case Precursor Combinations and Temporal Sequencing

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    Aircraft loss of control (LOC) is a leading cause of fatal accidents across all transport airplane and operational classes, and can result from a wide spectrum of hazards, often occurring in combination. Technologies developed for LOC prevention and recovery must therefore be effective under a wide variety of conditions and uncertainties, including multiple hazards, and their validation must provide a means of assessing system effectiveness and coverage of these hazards. This requires the definition of a comprehensive set of LOC test scenarios based on accident and incident data as well as future risks. This paper defines a comprehensive set of accidents and incidents over a recent 15 year period, and presents preliminary analysis results to identify worst-case combinations of causal and contributing factors (i.e., accident precursors) and how they sequence in time. Such analyses can provide insight in developing effective solutions for LOC, and form the basis for developing test scenarios that can be used in evaluating them. Preliminary findings based on the results of this paper indicate that system failures or malfunctions, crew actions or inactions, vehicle impairment conditions, and vehicle upsets contributed the most to accidents and fatalities, followed by inclement weather or atmospheric disturbances and poor visibility. Follow-on research will include finalizing the analysis through a team consensus process, defining future risks, and developing a comprehensive set of test scenarios with correlation to the accidents, incidents, and future risks. Since enhanced engineering simulations are required for batch and piloted evaluations under realistic LOC precursor conditions, these test scenarios can also serve as a high-level requirement for defining the engineering simulation enhancements needed for generating them

    Uniqueness Typing for Resource Management in Message-Passing Concurrency

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    We view channels as the main form of resources in a message-passing programming paradigm. These channels need to be carefully managed in settings where resources are scarce. To study this problem, we extend the pi-calculus with primitives for channel allocation and deallocation and allow channels to be reused to communicate values of different types. Inevitably, the added expressiveness increases the possibilities for runtime errors. We define a substructural type system which combines uniqueness typing and affine typing to reject these ill-behaved programs

    The Aussie, 1918-1931: cartoons, digger remembrance and First World War identity

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    Feelings of community, cultural definition and memory were kept alive through the soldiers’ mass circulation tabloid, the Aussie, examined here in the light of theorization of memory and representation, applied to both text and cartoons. The publication’s aim for veterans’ values to become shared national values is analysed in the light of its high profile usage of soft cartoon humour and also of nostalgia – highlighting the limitations as well as the effectiveness in terms of Australia’s evolving national identity. When the post-war economic situation worsened, deeper issues of national tension were glossed over by the use of scapegoats such as ‘profiteers’ and ‘lazy workers’. The armed forces were obliged to take on a political role of lobbying for their cause, but the Aussie as ‘cheerful friend’ experienced its own identity crisis that proved to be terminal
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