3,445 research outputs found

    Autonomous integrated GPS/INS navigation experiment for OMV. Phase 1: Feasibility study

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    The phase 1 research focused on the experiment definition. A tightly integrated Global Positioning System/Inertial Navigation System (GPS/INS) navigation filter design was analyzed and was shown, via detailed computer simulation, to provide precise position, velocity, and attitude (alignment) data to support navigation and attitude control requirements of future NASA missions. The application of the integrated filter was also shown to provide the opportunity to calibrate inertial instrument errors which is particularly useful in reducing INS error growth during times of GPS outages. While the Orbital Maneuvering Vehicle (OMV) provides a good target platform for demonstration and for possible flight implementation to provide improved capability, a successful proof-of-concept ground demonstration can be obtained using any simulated mission scenario data, such as Space Transfer Vehicle, Shuttle-C, Space Station

    Participatory crop improvement: the challenges of and opportunities for institutionalisation in the Indian public research sector

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    This thesis considers Participatory Crop Improvement (PCI) methodologies and examines the reasons behind their continued contestation and limited mainstreaming in conventional modes of crop improvement research within National Agricultural Research Systems (NARS). In particular, it traces the experiences of a long-established research network with over 20 years of experience in developing and implementing PCI methods across South Asia, and specifically considers its engagement with the Indian NARS and associated state-level agricultural research systems. In order to address the issues surrounding PCI institutionalisation processes, a novel conceptual framework was derived from a synthesis of the literatures on Strategic Niche Management (SNM) and Learning-based Development Approaches (LBDA) to analyse the socio-technical processes and structures which constitute the PCI ‘niche’ and NARS ‘regime’. In examining the niche and regime according to their socio-technical characteristics, the framework provides explanatory power for understanding the nature of their interactions and the opportunities and barriers that exist with respect to the translation of lessons and ideas between niche and regime organisations. The research shows that in trying to institutionalise PCI methods and principles within NARS in the Indian context, PCI proponents have encountered a number of constraints related to the rigid and hierarchical structure of the regime organisations; the contractual mode of most conventional research, which inhibits collaboration with a wider group of stakeholders; and the time-limited nature of PCI projects themselves, which limits investment and hinders scaling up of the innovations. It also reveals that while the niche projects may be able to induce a ‘weak’ form of PCI institutionalisation within the Indian NARS by helping to alter their institutional culture to be more supportive of participatory plant breeding approaches and future collaboration with PCI researchers, a ‘strong’ form of PCI institutionalisation, in which NARS organisations adopt participatory methodologies to address all their crop improvement agenda, is likely to remain outside of the capacity of PCI development projects to deliver

    Predicting ecosystem shifts requires new approaches that integrate the effects of climate change across entire systems.

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    Most studies that forecast the ecological consequences of climate change target a single species and a single life stage. Depending on climatic impacts on other life stages and on interacting species, however, the results from simple experiments may not translate into accurate predictions of future ecological change. Research needs to move beyond simple experimental studies and environmental envelope projections for single species towards identifying where ecosystem change is likely to occur and the drivers for this change. For this to happen, we advocate research directions that (i) identify the critical species within the target ecosystem, and the life stage(s) most susceptible to changing conditions and (ii) the key interactions between these species and components of their broader ecosystem. A combined approach using macroecology, experimentally derived data and modelling that incorporates energy budgets in life cycle models may identify critical abiotic conditions that disproportionately alter important ecological processes under forecasted climates

    27 - Effects of temperature during non-breeding months on size of three species of sparrow

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    Earth’s climate has warmed at an average rate of 0.17°C (0.31°F) per decade since 1970, and many scientists question how birds might adapt to this temperature change. Vertebrate body size likely has been associated with temperature based on two prominent hypotheses. Bergmann’s rule states that body size is larger in cooler climates because larger-bodied animals are better able to maintain stable internal temperatures. Allen’s rule states that appendages are smaller in cooler climates to decrease the amount surface area to lose heat. We hypothesize that as temperatures increase, body mass will decrease and wing chord will increase. We captured 932 swamp sparrows, 794 song sparrows, and 373 field sparrows at Panola Mountain State Park, in Stockbridge, GA between 2007-2017. We recorded the hatch year by back-calculating from age at capture, body mass, and wing chord length. We compared these measurements to the average temperature during non-breeding months at Panola Mountain, obtained from the National Oceanic and Atmospheric Administration database. Swamp sparrows born in warmer years were smaller in eight out of the nine years, as predicted by Bergmann’s rule. Similarly, Swamp sparrows born in warmer years had larger wing chords in eight out of nine years, as predicted by Allen’s rule. Neither Song sparrow nor Field sparrow mass or wing chord length were associated with temperature in any years. Our study shows that Swamp sparrow size may be affected by the temperature during their first winter and may be more susceptible to climate changes than other sparrow species

    Comparative population genetics of the German shepherd dog in South Africa

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    Modern breeding practices strive to achieve distinctive phenotypic uniformity in breeds of dogs, but these strategies are associated with the inevitable loss of genetic diversity. Thus, in parallel with the morphological variation displayed by breeds, purebred dogs commonly express genetic defects as a result of the inbreeding associated with artificial selection and the reduction of selection against disease phenotypes. Microsatellite marker analyses of 15 polymorphic canine loci were used to investigate measures of genetic diversity and population differentiation within and between German-bred and South African-bred German shepherd dogs. These data were quantified by comparison with typically outbred mongrel or crossbred dogs. Both the imported and locally-bred German shepherd dogs exhibited similar levels of genetic diversity. The breed is characterised by only a moderate loss of genetic diversity relative to outbred dogs, despite originating from a single founding sire and experiencing extensive levels of inbreeding throughout the history of the breed. Non-significant population differentiation between the ancestral German and derived South African populations indicates sufficient contemporary gene flow between these populations, suggesting that migration resulting from the importation of breeding stock has mitigated the effects of random genetic drift and a population bottleneck caused by the original founder event in South Africa. Significant differentiation between the combined German shepherd dog population and the outbred dogs illustrates the effects of selection and genetic drift on the breed since its establishment just over 100 years ago

    Prevalence of clinical autistic traits within a homeless population: barriers to accessing homeless services

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    Recent research suggests a high prevalence rate of Autism Spectrum Conditions (ASC) amongst the homeless population. Although, it is well-documented that autistic people experienced many barriers to accessing health services, little is known about their challenges in accessing homeless services. Thus, the present study aimed to measure prevalence of high levels of autistic traits, and to identify barriers that prevent autistic people accessing homeless services. Participants recruited from homeless services (n = 65) completed the Autism Quotient-10 (AQ-10) alongside a questionnaire regarding perceived accessibility of homeless services. Results revealed that 18.5% of participants scored Above the Clinical Threshold of the AQ-10 (ACT-AQ). Moreover, the ACT-AQ group reported that encountering big groups in shared accommodation represent a significant barrier to engaging with homeless services. Further research is needed to identify the full degree of ASC representation and the factors that might prevent autistic homeless people accessing homeless services, and thus overcoming homelessness

    Monitoring water-chemistry evolution in the bentonite buffer using magnets: Effects of corrosion on buffer stability

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    Bentonite has been chosen as a buffer material by several national nuclear-waste management companies because of its swelling capacity and low water permeability, and because it retards the transport of radionuclides and corrosion products toward the geosphere. The aim of the present study was to develop a magnetic material that has the ability to detect changes in groundwater compositions in an underground nucleardeposit facility through variation in its magnetic properties with time. The present study has investigated the effect of the corrosion of NdFeB magnets on the Na-bentonite buffer under different environmental conditions. Seven different aqueous solutions were used for long-time exposure tests (708C, 5 months) with fragments of NdFeB magnets and powdered Na-bentonite. The corrosion of NdFeB alloy had no detectable effect on the mineralogy of the clay minerals, and any change on the bentonite matrix, measured through X-ray diffraction analysis, was related to the different initial chemistry of the solutions.© 2016 by the authors. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC-BY) license (http://creativecommons.org/licenses/by/4.0/)
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