237 research outputs found
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The Beagle landing site in Isidis Planitia
The Mars probe Beagle 2 will land in Isidis Planitia. This region satisfies the engineering constraints and has evidence for particularly volatile-rich subsoil. Isidis provides a suitable place for the lander to search for H2O and organic matter
A service oriented architecture for decision making in engineering design
Decision making in engineering design can be effectively addressed by using genetic algorithms to solve multi-objective problems. These multi-objective genetic algorithms (MOGAs) are well suited to implementation in a Service Oriented Architecture. Often the evaluation process of the MOGA is compute-intensive due to the use of a complex computer model to represent the real-world system. The emerging paradigm of Grid Computing offers a potential solution to the compute-intensive nature of this objective function evaluation, by allowing access to large amounts of compute resources in a distributed manner. This paper presents a grid-enabled framework for multi-objective optimisation using genetic algorithms (MOGA-G) to aid decision making in engineering design
Active Amplification of the Terrestrial Albedo to Mitigate Climate Change: An Exploratory Study
This study explores the potential to enhance the reflectance of solar
insolation by the human settlement and grassland components of the Earth's
terrestrial surface as a climate change mitigation measure. Preliminary
estimates derived using a static radiative transfer model indicate that such
efforts could amplify the planetary albedo enough to offset the current global
annual average level of radiative forcing caused by anthropogenic greenhouse
gases by as much as 30 percent or 0.76 W/m2. Terrestrial albedo amplification
may thus extend, by about 25 years, the time available to advance the
development and use of low-emission energy conversion technologies which
ultimately remain essential to mitigate long-term climate change. However,
additional study is needed to confirm the estimates reported here and to assess
the economic and environmental impacts of active land-surface albedo
amplification as a climate change mitigation measure.Comment: 21 pages, 3 figures. In press with Mitigation and Adaptation
Strategies for Global Change, Springer, N
Potential of MODIS ocean bands for estimating CO2 flux from terrestrial vegetation: A novel approach
[1] A physiologically-driven spectral index using two ocean-color bands of MODIS satellite sensor showed great potential to track seasonally changing photosynthetic light use efficiency (LUE) and stress-induced reduction in net primary productivity (NPP) of terrestrial vegetation. Based on these findings, we developed a simple ‘‘continuous field’’ model solely based on remotely sensed spectral data that could explain 88% of variability in flux-tower based daily NPP. For the first time, such a procedure is successfully tested at landscape level using satellite imagery. These findings highlight the unexplored potential of narrow-band satellite sensors to improve estimates of spatial and temporal distribution in terrestrial carbon flux. INDEX TERMS: 1615 Global Change: Biogeochemical processes (4805); 1640 Global Change: Remote sensing; 1694 Global Change: Instruments and techniques; 4806 Oceanography: Biological and Chemical: Carbon cycling
Spatio-temporal genetic tagging of a cosmopolitan planktivorous shark provides insight to gene flow, temporal variation and site-specific re-encounters
Migratory movements in response to seasonal resources often influence population structure and dynamics. Yet in mobile marine predators, population genetic consequences of such repetitious behaviour remain inaccessible without comprehensive sampling strategies. Temporal genetic sampling of seasonally recurring aggregations of planktivorous basking sharks, Cetorhinus maximus, in the Northeast Atlantic (NEA) affords an opportunity to resolve individual re-encounters at key sites with population connectivity and patterns of relatedness. Genetic tagging (19 microsatellites) revealed 18% of re-sampled individuals in the NEA demonstrated inter/multi-annual site-specific re-encounters. High genetic connectivity and migration between aggregation sites indicate the Irish Sea as an important movement corridor, with a contemporary effective population estimate (Ne) of 382 (CI = 241–830). We contrast the prevailing view of high gene flow across oceanic regions with evidence of population structure within the NEA, with early-season sharks off southwest Ireland possibly representing genetically distinct migrants. Finally, we found basking sharks surfacing together in the NEA are on average more related than expected by chance, suggesting a genetic consequence of, or a potential mechanism maintaining, site-specific re-encounters. Long-term temporal genetic monitoring is paramount in determining future viability of cosmopolitan marine species, identifying genetic units for conservation management, and for understanding aggregation structure and dynamics
The effectiveness of neighborhood watch
Background: Neighborhood watch (also known as block watch, apartment watch, home watch and
community watch) grew out of a movement in the US during the late 1960s that promoted
greater involvement of citizens in the prevention of crime. Since then, interest in
neighborhood watch has grown considerably and recent estimates suggest that over a quarter
of the UK population and over forty per cent of the US population live in areas covered by
neighborhood watch schemes.
Objectives: The primary aim of this review is to assess the effectiveness of neighborhood watch in
reducing crime
A comparative analysis of foliar chemical composition and leaf construction costs of beech (Fagus sylvatica L.), sycamore maple (Acer pseudoplatanus L.) and ash (Fraxinus excelsior L.) saplings along a light gradient
• Construction cost (g glucose g−1), chemical composition and morphology of
leaves of beech (Fagus sylvatica L.) and two co-occurring valuable
broadleaved species (sycamore maple – Acer pseudoplatanus L. – and ash –
Fraxinus excelsior L.) were investigated along a horizontal light
gradient (3–60% of above canopy radiation) and from top to bottom within the crowns in a
fairly even-aged mixed-species thicket established by natural regeneration beneath a
patchy shelterwood canopy.
• Construction cost and carbon concentration increased with irradiance in ash and
sycamore maple and were independent of irradiance in beech. Leaf traits expressed on an
area basis, like construction cost, nitrogen content and leaf mass (LMA) increased
significantly with irradiance in all three species and decreased from top to bottom within
crowns.
• The shade tolerant beech invested more glucose to produce a unit foliar biomass, but
less to build a unit foliar area due to lower LMA. Thereby beech was able to display a
greater total leaf area, what at least in parts counterbalanced the lower values of
Na as compared to ash and sycamore maple
Diving into the vertical dimension of elasmobranch movement ecology
Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements
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