189 research outputs found

    Potential of multi-species livestock farming to improve the sustainability of livestock farms: A review.

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    Diversified farming systems are proposed as a major mechanism to address the many sustainability issues of today's agriculture. Multi-species livestock farming, i.e. keeping two or more animal species simultaneously on the same farm, is an option that has received little attention to date. Moreover, most studies of multi-species livestock farming are limited, usually focusing on selected dimensions of farm sustainability and addressing lower organizational levels (i.e. within the farm) and rather limited time horizons (e.g. a few weeks in a grazing season). Thus, a comprehensive assessment of multi-species livestock farming in terms of farm sustainability is lacking. In this context, we outline and discuss potential benefits and limitations of multi-species livestock farming for livestock farm sustainability from existing literature and list issues on multi-species livestock farming requiring further research. We show that multi-species livestock farming has the potential to improve the three dimensions of sustainability reviewed - economic viability for farmers, environmental soundness and social acceptability by being respectful of animals and humans - as long as locally relevant farming practices are implemented, especially an appropriate stocking rate during grazing. If relevant practices are not observed, multi-species livestock farming may produce undesirable effects, such as competition for resource acquisition during grazing, parasitic cross-infection and more intense work peaks. Therefore, we identify four focal research areas for multi-species livestock farming. First, characterizing the management of multi-species livestock farms. To do this, we suggest considering the integration of production enterprises (e.g. cattle and sheep enterprises) within the farm from three perspectives: farming practices (e.g. grazing management), work organization and sales. Second, exploring the complementarity of livestock species on multi-species livestock farms. This is especially true for species combinations that have been largely ignored (e.g. ruminants and monogastrics), even though they may have potential due to complementary diet compositions and resource-acquisition strategies. Third, assessing the sustainability of multi-species livestock farm scenarios (current or alternative) according to the management practices and production conditions, which requires adapting existing methods/models or developing new ones. Fourth, characterizing conditions for success and obstacles for multi-species livestock farming along the value chain from production to consumption, considering stakeholders' objectives, work habits and constraints. Increasing understanding should help prioritize actions and organize them to scale up multi-species livestock farming

    Photometric Properties of Ceres from Telescopic Observations using Dawn Framing Camera Color Filters

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    The dwarf planet Ceres is likely differentiated similar to the terrestrial planets but with a water/ice dominated mantle and an aqueously altered crust. Detailed modeling of Ceres' phase function has never been performed to understand its surface properties. The Dawn spacecraft began orbital science operations at the dwarf planet in April 2015. We observed Ceres with flight spares of the seven Dawn Framing Camera color filters mounted on ground-based telescopes over the course of three years to model its phase function versus wavelength. Our analysis shows that the modeled geometric albedos derived from both the IAU HG model and the Hapke model are consistent with a flat and featureless spectrum of Ceres, although the values are ~10% higher than previous measurements. Our models also suggest a wavelength dependence of Ceres' phase function. The IAU G-parameter and the Hapke single-particle phase function parameter, g, are both consistent with decreasing (shallower) phase slope with increasing wavelength. Such a wavelength dependence of phase function is consistent with reddening of spectral slope with increasing phase angle, or phase-reddening. This phase reddening is consistent with previous spectra of Ceres obtained at various phase angles archived in the literature, and consistent with the fact that the modeled geometric albedo spectrum of Ceres is the bluest of all spectra because it represents the spectrum at 0 degree phase angle. Ground-based FC color filter lightcurve data are consistent with HST albedo maps confirming that Ceres' lightcurve is dominated by albedo and not shape. We detected a positive correlation between 1.1-micron absorption band depth and geometric albedo suggesting brighter areas on Ceres have absorption bands that are deeper.Comment: 40 pages, 9 figures, 5 tables. Accepted for publication in Icaru

    Quantifying and valuing carbon flows and stores in coastal and shelf ecosystems in the UK

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    Evidence shows that habitats with potential to mitigate against greenhouse gases emissions, by taking up and storing CO2, are being lost due to the effects of on-going human activities and climate change. The carbon storage by terrestrial habitats (e.g. tropical forests) and the role of coastal habitats (‘Blue Carbon’) as carbon storage sinks is well recognised. Offshore shelf sediments are also a manageable carbon store, covering ∌9% of global marine area, but not currently protected by international agreements to enable their conservation. Through a scenario analysis, we explore the economic value of the damage of human activities and climate change can inflict on UK marine habitats, including shelf sea sediments. In a scenario of increased human and climate pressures over a 25-year period, we estimate damage costs up to US$12.5 billion from carbon release linked to disturbance of coastal and shelf sea sediment carbon stores. It may be possible to manage socio-economic pressure to maintain sedimentary carbon storage, but the trade-offs with other global social welfare benefits such as food security will have to be taken into account. To develop effective incentive mechanisms to preserve these valuable coastal and marine ecosystems within a sustainability governance framework, robust evidence is required

    Olivine-rich exposures at Bellicia and Arruntia craters on (4) Vesta from Dawn FC

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    We present an analysis of the olivine-rich exposures at Bellicia and Arruntia craters using Dawn Framing Camera (FC) color data. Our results confirm the existence of olivine-rich materials at these localities as described by Ammannito et al. (2013a) using Visual Infrared Spectrometer (VIR) data. Analyzing laboratory spectra of various Howardite-Eucrite-Diogenite meteorites, high-Ca pyroxenes, olivines and olivine-orthopyroxene mixtures, we derive three FC spectral band parameters that are indicators of olivine-rich materials. Combining the three band parameters allows us, for the first time, to reliably identify sites showing modal olivine contents >40%. The olivine-rich exposures at Bellicia and Arruntia are mapped using higher spatial resolution FC data. The exposures are located on the slopes of outer/inner crater walls, on the floor of Arruntia, in the ejecta, as well as in nearby fresh small impact craters. The spatial extent of the exposures ranges from a few hundred meters to few kilometers. The olivine-rich exposures are in accordance with both the magma ocean and the serial magmatism model (e.g., Righter and Drake 1997; Yamaguchi et al. 1997). However, it remains unsolved why the olivine-rich materials are mainly concentrated in the northern hemisphere (~36-42{\deg} N, 46-74{\deg} E) and are almost absent in the Rheasilvia basin.Comment: Accepted for publication in Meteoritics and Planetary Scienc

    Global Photometric Properties of Asteroid (4) Vesta Observed with Dawn Framing Camera

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    Dawn spacecraft orbited Vesta for more than one year and collected a huge volume of multispectral, high-resolution data in the visible wavelengths with the Framing Camera. We present a detailed disk-integrated and disk-resolved photometric analysis using the Framing Camera images with the Minnaert model and the Hapke model, and report our results about the global photometric properties of Vesta. The photometric properties of Vesta show weak or no dependence on wavelengths, except for the albedo. At 554 nm, the global average geometric albedo of Vesta is 0.38+/-0.04, and the Bond albedo range is 0.20+/-0.02. The bolometric Bond albedo is 0.18+/-0.01. The phase function of Vesta is similar to those of S-type asteroids. Vesta's surface shows a single-peaked albedo distribution with a full-width-half-max ~17% relative to the global average. This width is much smaller than the full range of albedos (from ~0.55x to >2x global average) in localized bright and dark areas of a few tens of km in sizes, and is probably a consequence of significant regolith mixing on the global scale. Rheasilvia basin is about 10% brighter than the global average. The phase reddening of Vesta measured from Dawn Framing Camera images is comparable or slightly stronger than that of Eros as measured by the Near Earth Asteroid Rendezvous mission, but weaker than previous measurements based on ground-based observations of Vesta and laboratory measurements of HED meteorites. The photometric behaviors of Vesta are best described by the Hapke model and the Akimov disk- function, when compared with the Minnaert model, Lommel-Seeliger model, and Lommel- Seeliger-Lambertian model. The traditional approach for photometric correction is validated for Vesta for >99% of its surface where reflectance is within +/-30% of global average.Comment: 94 pages (double-spaced), 6 tables, 19 figure

    The HADES mission concept - astrobiological survey of Jupiter's icy moon Europa

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    The HADES Europa mission concept aims to provide a framework for an astrobiological in-depth investigation of the Jupiter moon Europa, relying on existing technologies and feasibility. This mission study proposes a system consisting of an orbiter, lander and cryobot as a platform for detailed exploration of Europa. While the orbiter will investigate the presence of a liquid ocean and characterize Europa's internal structure, the lander will survey local dynamics of the ice layer and the surface environment. The lander releases a cryobot, that melts into the ice, will sample the pristine subsurface and is expected to provide data on organic and gaseous content and putative bio-signatures. In summary, we present the scientific objectives for an astrobiological investigation of Europa, resulting in a mission concept with a detailed evaluation of scientific instrumentation, mission sequences, basic design of the spacecraft, technology needs and cost estimation

    Asteroid Ryugu before the Hayabusa2 encounter

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    Asteroid (162173) Ryugu is the target object of Hayabusa2, an asteroid exploration and sample return mission led by Japan Aerospace Exploration Agency (JAXA). Ground-based observations indicate that Ryugu is a C-type near-Earth asteroid with a diameter of less than 1 km, but the knowledge of its detailed properties is very limited prior to Hayabusa2 observation. This paper summarizes our best understanding of the physical and dynamical properties of Ryugu based on ground-based remote sensing and theoretical modeling before the Hayabusa2’s arrival at the asteroid. This information is used to construct a design reference model of the asteroid that is used for the formulation of mission operation plans in advance of asteroid arrival. Particular attention is given to the surface properties of Ryugu that are relevant to sample acquisition. This reference model helps readers to appropriately interpret the data that will be directly obtained by Hayabusa2 and promotes scientific studies not only for Ryugu itself and other small bodies but also for the solar system evolution that small bodies shed light on.Additional co-authors: Guy Libourel, Roy Lichtenheldt, Alessandro Maturilli, Scott R. Messenger, Tatsuhiro Michikami, Hideaki Miyamoto, Stefano Mottola, Thomas MĂŒller, Akiko M. Nakamura, Larry R. Nittler, Kazunori Ogawa, Tatsuaki Okada, Ernesto Palomba, Naoya Sakatani, Stefan E. Schröder, Hiroki Senshu, Driss Takir, Michael E. Zolensky and International Regolith Science Group (IRSG) in Hayabusa2 projec

    The HADES mission concept – Astrobiological survey of Jupiter's icy moon Europa

    Get PDF
    The HADES Europa mission concept aims to provide a framework for an astrobiological in-depth investigation of the Jupiter moon Europa, relying on existing technologies and feasibility. This mission study proposes a system consisting of an orbiter, lander and cryobot as a platform for detailed exploration of Europa. While the orbiter will investigate the presence of a liquid ocean and characterize Europa's internal structure, the lander will survey local dynamics of the ice layer and the surface environment. The lander releases a cryobot, that melts into the ice, will sample the pristine subsurface and is expected to provide data on organic and gaseous content and putative bio-signatures. In summary, we present the scientific objectives for an astrobiological investigation of Europa, resulting in a mission concept with a detailed evaluation of scientific instrumentation, mission sequences, basic design of the spacecraft, technology needs and cost estimations
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