477 research outputs found

    Sustainable development of smallholder crop-livestock farming in developing countries

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    Meeting the growing demand for animal-sourced food, prompted by population growth and increases in average per-capita income in low-income countries, is a major challenge. Yet, it also presents significant potential for agricultural growth, economic development, and reduction of poverty in rural areas. The main constraints to livestock producers taking advantage of growing markets include; lack of forage and feed gaps, communal land tenure, limited access to land and water resources, weak institutions, poor infrastructure and environmental degradation. To improve rural livelihood and food security in smallholder crop-livestock farming systems, concurrent work is required to address issues regarding efficiency of production, risk within systems and development of whole value chain systems. This paper provides a review of several forage basedstudies in tropical and non-tropical dry areas of the developing countries. A central tenet of this paper is that forages have an essential role in agricultural productivity, environmental sustainability and livestock nutrition in smallholder mixed farming systems

    Next Generation Solar Array Technologies for Small Satellites

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    Recent advances in Shape Memory Alloy (SMA), Elastic Memory Composites (EMC), and ultra- light composites along with thin-film Copper-Indium- Diselinide (CIS) photovoltaics have offered the potential to provide solar array systems for small satellites that are significantly lighter than the current state of the practice. The Air Force Research Laboratory (AFRL), National Aeronautics and Space Administration (NASA) Langley, Defense Advanced Research Projects Agency (DARPA), and Lockheed Martin are jointly sponsoring an effort that will develop and, in partnership with AeroAstro, demonstrate advanced technologies for solar array applications. These technologies will result in advances that include cost, weight, risk, reliability, and power. Conventional state-of-the-practice solar arrays utilize rigid honeycomb panels to provide the structural support for the crystalline Silicon (Si) or Gallium Arsenide (GaAs) solar cells. Rigid composite panel structural and manufacturing methods have placed a practical producible limit on the power to weight efficiency of today’s solar panels. This limit is about 60 Watts per kilogram (W/kg). New technologies are needed to break this power to weight barrier and meet future DOD and NASA space power requirements. A potential solution to this problem, are the technologies that are being developed under the Lightweight Flexible Solar Array (LFSA) program. The LFSA will demonstrate key technologies on four space flights. The first space opportunity consisted of a flight experiment of a Shape Memory Alloy (SMA) deployment hinge that was demonstrated on the Space Shuttle Columbia (STS-93) in July 1999. The second flight opportunity consisted of a sub-scale twopanel solar array that was demonstrated on NASA’s Earth Observing-1 spacecraft in November 2000. The third and fourth flight opportunities will transition thin-film solar arrays into SSC02-II-2 Fosness, Eugene 2 16th Annual/USU Conference on Small Satellites operational spacecraft systems, specifically on the AeroAstro/Astronautic Technology Sdn. Bhd. (ATSB) Small Payload ORbit Transfer (SPORT™) vehicle in 2003 and the Team Encounter solar sail in 2004. The synergistic merging of the new, innovative technologies into an advanced lightweight thin- film solar array will meet the requirements of the emerging next generation of small satellites. The implementation of these new techno logies directed at lightweight solar arrays will result in significant weight and volume reductions over current satellite systems. The SMA devices will provide a controlled shock-less deployment of the solar array and improved testability due to mechanism re-set capability. Additionally, the SMA actuators will eliminate or minimize deployment motors, mechanisms, and part count. The LFSA program is a pathfinder for next generation rollout arrays that increase specific power densities to \u3e200 W/kg

    Risk of Climate-Related Impacts on Global Rangelands – A Review and Modelling Study

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    Climate change threatens the ability of global rangelands to provide food, support livelihoods and deliver important ecosystems services. The extent and magnitude of potential impacts are however poorly understood. In this study, we review the risk of climate impacts along the rangeland systems food supply chain. We also present results from biophysical modelling simulations and spatial data analyses to identify where and to what extent rangelands may be at climatic risk. Although a quantification of the net impacts of climate change on rangeland production systems is beyond the reach of our current understanding, there is strong evidence that there will be impacts throughout the supply chain, from feed and animal production to processing, storage, transport, retailing and human consumption. Regarding grazing biomass production, this study finds that mean herbaceous biomass is projected to decrease across global rangelands between 2000 and 2050 under RCP 8.5 (-4.7%), while inter- (year-to-year) and intra- (month-to-month) annual variabilities are projected to increase (+21.3% and +8.2%, respectively). These averaged global estimates mask large spatial heterogeneities, with 74% of global rangeland area projected to experience a decline in mean biomass, 64% an increase in inter-annual variability and 54% an increase in intra-annual variability. The potentially most damaging vegetation trends for livestock production (i.e., simultaneous decreases in mean biomass and increases in inter-annual variability) are projected to occur in rangeland communities that are currently the most vulnerable (here, with the lowest livestock productivities and economic development levels and with the highest projected increases in human population densities). Large uncertainties remain as to climate futures and the exposure and responses of the interlinked human and natural systems to climatic changes over time. Consequently, adaptation choices will need to build on robust methods of designing, implementing and evaluating detailed development pathways, and account for a wide range of possible futures

    How does visual language affect crossmodal plasticity and cochlear implant success?

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    Cochlear implants (CI) are the most successful intervention for ameliorating hearing loss in severely or profoundly deaf children. Despite this, educational performance in children with CI continues to lag behind their hearing peers. From animal models and human neuroimaging studies it has been proposed the integrative functions of auditory cortex are compromised by crossmodal plasticity. This has been argued to result partly from the use of a visual language. Here we argue that 'cochlear implant sensitive periods' comprise both auditory and language sensitive periods, and thus cannot be fully described with animal models. Despite prevailing assumptions, there is no evidence to link the use of a visual language to poorer CI outcome. Crossmodal reorganisation of auditory cortex occurs regardless of compensatory strategies, such as sign language, used by the deaf person. In contrast, language deprivation during early sensitive periods has been repeatedly linked to poor language outcomes. Language sensitive periods have largely been ignored when considering variation in CI outcome, leading to ill-founded recommendations concerning visual language in CI habilitation

    Family unity objectives of parents who teach their children: Ideological and pedagogical orientations to home schooling

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    This article examines parents who teach their children at home. Using the results from two qualitative studies the article suggests, while families have complex motives for teaching their children at home, an important commonality underlies their decision. Regardless of their orientation to home schooling the parents in these two studies felt that establishing a home school would allow them to maintain or further develop unity within the family. The article suggests a family's decision to home school is often made in an attempt to resist the effects on the family unit of urbanization and modernization. The policy implications of this finding are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43875/1/11256_2005_Article_BF01112403.pd

    A look at the other 90 per cent: Investigating British Sign Language vocabulary knowledge in deaf children from different language learning backgrounds

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    In this study we present new data on deaf children's receptive and expressive vocabulary knowledge in British Sign Language (BSL) from a sample consisting of children with deaf parents, children with hearing parents, and children with additional needs. Their performance on three BSL vocabulary tasks was compared with (previously reported findings from) a sample of deaf fluent signers. We use these data to assess the effects of some key demographic/ child variables on deaf signing children's vocabulary and discuss findings in the relation to the meaning of 'normative' data and samples for this heterogeneous population. Findings show no effect of the presence of additional disabilities on participants' scores for any of the three tasks. As expected, chronological age is the most significant factor in performance on all vocabulary tasks while the number of deaf relatives only becomes statistically significant for the form recall task. This study contributes to the field of sign language assessment by seeking to identify key variables in heterogeneity and how these variables affect signed vocabulary acquisition with the long-term objective of informing intervention

    Research specialties as emergent phenomena: Connecting emergence theory and scientometrics

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    This short paper represents an initial effort to connect the emergence theory literature with the bibliometric, informetric, and scientometic literatures. It begins with a prominent definition of emergence, and then connects each of the components of this definition with the relevant insights about the development of new scientific and technical concepts or research specialties. Finally, it concludes with a discussion of the relationship between these two distinct areas of scholarly inquiry and the need for further exploration of this intersection.Intelligence Advanced Research Projects Activity (IARPA) viapublished or submitted for publicationis peer reviewe
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