149 research outputs found

    Synergy of debris mitigation and removal

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    At the beginning of the twenty-first century there was considerable effort made using evolutionary models to assess the effectiveness of post-mission disposal (PMD) and other mitigation measures to stabilise the growth of the debris population in low Earth orbit (LEO). Subsequently, this activity led to the recommendation of a “25-year rule” for the post-mission disposal of spacecraft and orbital stages intersecting the LEO region. At the time, it was anticipated that the 25-year rule, together with passivation and suppression of mission-related debris, would be sufficient to prevent the continued growth of the LEO debris population. However, in the last decade both the LEO debris environment and the debris modelling capability have seen significant changes. In particular, recent population growth has been driven by a number of major break-ups, including the intentional destruction of the Fengyun-1C spacecraft and the collision between Iridium 33 and Cosmos 2251. State-of-the-art evolutionary models now indicate that mitigation measures alone are insufficient to stabilise the LEO debris population. Consequently, this has led to considerable interest in the remediation of the debris environment and, especially, in debris removal. Yet there is a reluctance to revisit the role of PMD within the wider goal of remediation even though it does not provide the solution that was expected. Thus, there is a risk that the approach to remediation will follow a sequential, “over-the-fence” philosophy, which tends to deliver costly, and less than optimal solutions. In this paper, we present a new and large study of debris mitigation and removal using the University of Southampton’s evolutionary model, DAMAGE, together with the latest MASTER model population of objects > 10 cm in LEO. Here, we have employed a concurrent approach to remediation, whereby changes to the PMD rule and the inclusion of other mitigation measures have been considered alongside multiple removal strategies. In this way, we have been able to demonstrate the synergy of these measures and to identify aggregate solutions to the space debris problem. The results suggest that reducing the PMD decay rule offers benefits that include an increase in the effectiveness of debris removal and a corresponding increase in the confidence that these combined measures will lead to the stabilisation of the LEO debris population

    Degradation and forgone removals increase the carbon impact of intact forest loss by 626%

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    Intact tropical forests, free from substantial anthropogenic influence, store and sequester large amounts of atmospheric carbon but are currently neglected in international climate policy. We show that between 2000 and 2013, direct clearance of intact tropical forest areas accounted for 3.2% of gross carbon emissions from all deforestation across the pantropics. However, full carbon accounting requires the consideration of forgone carbon sequestration, selective logging, edge effects, and defaunation. When these factors were considered, the net carbon impact resulting from intact tropical forest loss between 2000 and 2013 increased by a factor of 6 (626%), from 0.34 (0.37 to 0.21) to 2.12 (2.85 to 1.00) petagrams of carbon (equivalent to approximately 2 years of global land use change emissions). The climate mitigation value of conserving the 549 million ha of tropical forest that remains intact is therefore significant but will soon dwindle if their rate of loss continues to accelerate

    Assessing the genetic diversity of rice originating from Bangladesh, Assam and West Bengal

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    Acknowledgements This work was funded by BBSRC research project BB/J00336/1. FS and a part of the proportion of the cost of the Illumina genotyping was funded by a Beachell-Borlag International Fellowship. The authors would like to acknowledge the help of Dr MK Sarmah in collecting seed samples of the landraces and improved cultivars from Assam used in this study and Dr. Ma. Elizabeth B. Naredo and Ms. Sheila Mae Q. Mercado for handling of IRGC accessions and preparation of DNAs for genotyping. All rice seeds used here were obtained with MTA agreements and seed and dry leaves imported into the UK under import licence IMP⁄SOIL⁄18⁄2009 issued by Science and Advice for Scottish Agriculture.Peer reviewedPublisher PD

    Threatened ecosystems of Myanmar. An IUCN Red List of ecosystems assessment. Version 1.0.

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    [Excerpt:] Myanmar's Red List of Ecosystems is a tool to understand our threats and plan for conservation and sustainable management. Forests constitute the dominant ecosystems in Myanmar, and we are blessed with high forest cover (42.92%) and diversity, with 36 of our 64 ecosystems identified as forest and mangrove. These forests and biodiversity underpin a range of ecosystem services which are central to Myanmar’s sustainable development, supporting human and resource needs, and contributing to a more stable climate. The loss of forests and our biodiversity leads to degradation and deterioration of ecosystem services and threatens Myanmar’s irreplaceable ecological heritage. We often discuss ecosystem services but this study documents Myanmar’s terrestrial ecosystem typology and spatial distribution for the first time. This is one of the first ecosystem red lists developed within ASEAN and this will inform our implementation for decades to come to inform legislation, land-use planning, protected area expansion, monitoring and reporting, and ecosystem management. To sustain our forests and our biodiversity we need to sustainably manage all of these incredible ecosystems

    Optical Remote Sensing of Submerged Aquatic Vegetation: Opportunities for Shallow Clearwater Streams

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    Remote sensing has rarely been used as a tool to map and monitor submerged aquatic vegetation (SAV) in rivers, due to a combination of insufficient spatial resolution of available image data and strong attenuation of light in water through absorption and scattering. The latter process reduces the possibility to use spectral reflectance information to accurately classify submerged species. However, increasing availability of very high resolution (VHR) image data may enable the use of shape and texture features to help discriminate between species by taking an object based image analysis (OBIA) approach, and overcome some of the present limitations. This study aimed to investigate the possibility of using optical remote sensing for the detection and mapping of SAV. It firstly looked at the possibilities to discriminate submerged macrophyte species based on spectral information only. Reflectance spectra of three macrophyte species were measured in situ across a range of submergence depths. The results showed that water depth will be a limiting factor for the classification of species from remote sensing images. Only Spiked Water Milfoil (Myriophyllum spicatum) was indicated as spectrally distinct through ANOVA analysis, but subsequent Jeffries–Matusita distance analysis did not confirm this. In particular Water Crowfoot (Ranunculus fluitans) and Pondweed (Potamogeton pectinatus) could not be discriminated at 95% significance level. Spectral separability of these two species was also not possible without the effect of an overlying water column. Secondly, the possibility to improve species discrimination, using spatial and textural information was investigated for the same SAV species. VHR image data was acquired with a Near Infrared (NIR) sensitive DSLR camera from four different heights including a telescopic pole and a Helikite UAS. The results show that shape and texture information can improve the detection of the spectrally similar Pondweed and Water Crowfoot from VHR image data. The best performing feature ‘length/width ratio of sub-objects’ was obtained through expert knowledge. All of the shape and texture based features performed better at species differentiation than the spectrally based features. In conclusion this study has shown that there is considerable potential for the combination of VHR data and OBIA to map SAV in shallow stream environments, which can benefit species monitoring and management

    Development and Evaluation of Sensor Concepts for Ageless Aerospace Vehicles: Report 5 - Phase 2 Implementation of the Concept Demonstrator

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    This report describes the second phase of the implementation of the Concept Demonstrator experimental test-bed system containing sensors and processing hardware distributed throughout the structure, which uses multi-agent algorithms to characterize impacts and determine a suitable response to these impacts. This report expands and adds to the report of the first phase implementation. The current status of the system hardware is that all 192 physical cells (32 on each of the 6 hexagonal prism faces) have been constructed, although only four of these presently contain data-acquisition sub-modules to allow them to acquire sensor data. Impact detection.. location and severity have been successfully demonstrated. The software modules for simulating cells and controlling the test-bed are fully operational. although additional functionality will be added over time. The visualization workstation displays additional diagnostic information about the array of cells (both real and simulated) and additional damage information. Local agent algorithms have been developed that demonstrate emergent behavior of the complex multi-agent system, through the formation of impact damage boundaries and impact networks. The system has been shown to operate well for multiple impacts. and to demonstrate robust reconfiguration in the presence of damage to numbers of cells

    Development and Evaluation of Sensor Concepts for Ageless Aerospace Vehicles: Report 4 - Phase 1 Implementation of the Concept Demonstrator

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    This report describes the first phase of the implementation of the Concept Demonstrator. The Concept Demonstrator system is a powerful and flexible experimental test-bed platform for developing sensors, communications systems, and multi-agent based algorithms for an intelligent vehicle health monitoring system for deployment in aerospace vehicles. The Concept Demonstrator contains sensors and processing hardware distributed throughout the structure, and uses multi-agent algorithms to characterize impacts and determine an appropriate response to these impacts

    MYC regulates fatty acid metabolism through a multigenic program in claudin-low triple negative breast cancer

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    Background: Recent studies have suggested that fatty acid oxidation (FAO) is a key metabolic pathway for the growth of triple negative breast cancers (TNBCs), particularly those that have high expression of MYC. However, the underlying mechanism by which MYC promotes FAO remains poorly understood. Methods: We used a combination of metabolomics, transcriptomics, bioinformatics, and microscopy to elucidate a potential mechanism by which MYC regulates FAO in TNBC. Results: We propose that MYC induces a multigenic program that involves changes in intracellular calcium signalling and fatty acid metabolism. We determined key roles for fatty acid transporters (CD36), lipases (LPL), and kinases (PDGFRB, CAMKK2, and AMPK) that each contribute to promoting FAO in human mammary epithelial cells that express oncogenic levels of MYC. Bioinformatic analysis further showed that this multigenic program is highly expressed and predicts poor survival in the claudin-low molecular subtype of TNBC, but not other subtypes of TNBCs, suggesting that efforts to target FAO in the clinic may best serve claudin-low TNBC patients. Conclusion: We identified critical pieces of the FAO machinery that have the potential to be targeted for improved treatment of patients with TNBC, especially the claudin-low molecular subtype
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