6974 research outputs found
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A place-based assessment of biodiversity intactness in sub-Saharan Africa
Full text linkMaintaining biodiversity is central to the sustainable development agenda1. However, a lack of context-specific biodiversity information at policy-relevant scales has posed major limitations to decision-makers2,3. To address this challenge, we undertook a comprehensive assessment of the biodiversity intactness of sub-Saharan Africa4 using place-based knowledge of 200 African biodiversity experts5. We estimate that the region has on average lost 24% of its pre-colonial and pre-industrial faunal and floral population abundances, ranging from losses of <20% for disturbance-adapted herbaceous plants to 80% for some large mammals. Rwanda and Nigeria are the least intact (<55%), whereas Namibia and Botswana are the most intact (>85%). Notably, most remaining organisms occur in unprotected, relatively untransformed rangelands and natural forests. Losses in biodiversity intactness in the worst-affected biomes are driven by land transformation into cropland in grasslands and fynbos (Mediterranean-type ecosystems), by non-agricultural degradation in forests and by a combination of the two drivers in savannas. This assessment provides decision-makers with multifaceted, contextually appropriate and policy-relevant information on the state of biodiversity in an understudied region of the world. Our approach could be used in other regions, including better-studied localities, to integrate contextual, place-based knowledge into multiscale assessments of biodiversity status and impacts.</p
Drought Response in Miscanthus:Breeding Increases Radiation and Water Use Efficiency Over Three Contrasting Years in Central Germany
No full textMore and new sources of biomass are needed for renewable energy and renewable products for the bioeconomy. A leading new source of biomass is the highly sustainable perennial grass crop Miscanthus. The majority of the Miscanthus crop comprises a clone of Miscanthus × giganteus (M × g) of limited genetic variation and poor yield under dry growth conditions. The parental species of M × g, M. sacchariflorus and M. sinensis , are distributed over a large geographical range in Eastern Asia and may be used to improve on M × g. From breeding trials, we selected seven novel hybrids and two control genotypes including M × g. We grew these in a field experiment on drought‐prone soil in Germany with and without irrigation. To identify superior Miscanthus types, we estimated radiation use efficiency (RUE), yield and water use efficiency (WUE) from within‐season measurements made over three contrasting growing seasons. Temporal variations in RUE and WUE for different genotypes varied significantly and two novel hybrids, WAT6 and WAT8, achieved the highest yields. To achieve goodness of fit to yield measurements, genotype‐specific parameters for process descriptions in the model MiscanFor were adjusted for the two superior genotypes. These parameters included earlier shooting and an increased threshold of overheating. When the model was run over ten years, despite generating the highest yield values, WAT8 accumulated less biomass than WAT6 over the longer term. The response of WUE to variation in soil capillary pressure and vapour pressure deficit was examined. WUE of M × g increased with the severity of water stress then declined again. The superior yielding genotypes were more able to sustain biomass accumulation and/or water use under the highest stress. We believe that combining physiology with crop modelling is a powerful way to inform genetic and agronomic improvements needed to secure the future supply of biomass for the bioeconomy
Identifying a cell wall ideotype for increased soil carbon contents associated with Miscanthus cultivation.
No full textDedicated biomass crops are widely accepted as an important part of decarbonising economies. Miscanthus is a leading dedicated biomass crop that embodies high yield with many co-benefits including soil carbon sequestration plus the benefits of perennial agronomy. Breeding programmes for Miscanthus are in their infancy but it is apposite to consider the potential for breeding improved soil carbon sequestration. We focussed on gross biomass inputs from leaf, roots and rhizome and examined both dry weight and cell wall composition as key factors that influence soil carbon sequestration. We measured lignin, cellulose, hemicellulose, carbon and nitrogen from all three tissues in different Miscanthus genotypes that had been grown in field plots and compared for soil carbon. There was a significant genotypic effect on most compositional traits from all three tissue types and composition also varied between tissue types. When combined with soil C data from field grown plants, lignin and lignin:N were shown to be useful predictive factors (along with soil depth) for total soil organic C and this combination of factors explained 86% of the model variance for Miscanthus derived soil C. Examples of trade-offs were observed but a high sequestering plant includes low root lignin and high belowground biomas
Nonthermal Pressures:Key to Energy Balance and Structure Formation near Sgr A* in the Milky Way
No full textThe circumnuclear region of the Galactic center offers a unique laboratory to study energy balance and structure formation around Sgr A⋆. This work investigates thermal and nonthermal processes within a 7 pc distance from Sgr A⋆. Using MeerKAT 1.3 GHz radio continuum data and Atacama Large Millimeter/submillimeter Array H40α radio recombination line emission from the ACES survey, we separate free–free and synchrotron components at ∼0.2 pc resolution. With a thermal fraction of ≃13%, the 1.3 GHz emission shows tight correlations with the Herschel PACS IR data. The correlation between the equipartition magnetic field and molecular gas traced by JCMT 12CO (J = 3 → 2) observations reveals a balance between the magnetic field, cosmic rays, and molecular gas pressures south of the circumnuclear disk on ∼0.7 pc scales. Unlike the magnetic field and ionized gas, the molecular gas density declines in the cavity (R ≤ 2 pc) toward the center, likely due to feedback from Sgr A⋆. We find that nonthermal pressure from turbulent gas nearly balances magnetic and cosmic-ray pressures and exceeds the thermal pressure by 2 orders of magnitude. The medium surrounding Sgr A⋆ is filled by a low-β (thermal-to-magnetic energy ratio), supersonic plasma, with an Alfvén Mach number ≃ 4 (assuming equipartition). Analysis of the mass-to-magnetic flux ratio suggests that the circumnuclear region is mostly subcritical and, therefore, the magnetic field can help stabilize gas clouds against gravitational collapse
Valorisation of spent mushroom substrate by secondary microbial fermentation
No full textGlobal mushroom production exceeds 45 million tonnes, involving growth on a lignocellulosic substrate. More than 70% of these mushrooms are considered wild mushrooms that are grown on a lignocellulose substrate. At the end of the growth cycle, the remaining spent mushroom substrate (SMS) is considered waste with little value and is often discarded. The limited information available on the fibre content remaining in SMS indicates that different white-rot fungi can result in significant differences in the hemicellulose and lignin content, which in turn may impact the second fermentation step. Secondary fermentation has found uses in the production of biofuels, as a preserved ruminant feed, for enzyme production, in the formation of microbial compounds, and as an amended fertiliser. Finally, achieving secondary fermentation of SMS could involve the development and use of larger-scale solid-state fermentation. This review article has shown that research into secondary fermentation of SMS has been a relatively new field occurring over the past 14 years. Graphical abstract
Uniformity of heating across sample holders during luminescence measurements
No full textFor luminescence research, samples are often heated prior to and/or during measurement to measure the thermoluminescence (TL) signal or to remove charge from shallow traps. The reproducibility and repeatability of luminescence measurements will be influenced by how consistently and uniformly the samples are heated, both within a single aliquot and between different readers or sample positions. While the effects of temperature lag during heating have been intensively studied, the spatial uniformity of temperature across samples has received less attention. This study presents spatially-resolved measurements of the temperature of the heating strip, a steel cup and an aluminium single grain disc in a Risø TL/OSL DA20 reader. Temperature is calculated using black body emissions from the three materials, detected with an Electron Multiplying Charge Coupled Device (EMCCD). The results show that temperature is not spatially uniform across any of the three materials, although the degree of variation differs between them. The largest temperature variation is observed across the steel cup (∼18 % at a temperature of 500 °C), followed by the heating strip (∼8 % at a temperature of 500 °C), and then the single grain disc (∼2 % at a temperature of 250 °C). The steel cup also has greater anisotropy in temperature compared to the single grain disc. This study suggests that spatial variation in temperature can be minimised by using sample holders made of materials with high thermal conductivity (e.g. aluminium or silver), and that the impact of thermal variation can be reduced by restricting samples to the central portion of a sample holder (e.g. the central 2 mm of a sample holder (i.e. ‘small aliquots’)).</p
Self-supervised multimodal change detection based on difference contrast learning for remote sensing imagery
No full textMost existing change detection (CD) methods target homogeneous images. However, in real-world scenarios like disaster management, where CD is urgent and pre-changed and post-changed images are typical of different modalities, significant challenges arise for multimodal change detection (MCD). One challenge is that bi-temporal image pairs, sourced from distinct sensors, may cause an image domain gap. Another issue surfaces when multimodal bi-temporal image pairs require collaborative input from domain experts who are specialised among different image fields for pixel-level annotation, resulting in scarce annotated samples. To address these challenges, this paper proposes a novel self-supervised difference contrast learning framework (Self-DCF). This framework facilitates networks training without labelled samples by automatically exploiting the feature information inherent in bi-temporal imagery to supervise each other mutually. Additionally, a Unified Mapping Unit reduces the domain gap between different modal images. The efficiency and robustness of Self-DCF are validated on five popular datasets, outperforming state-of-the-art algorithms.</p
Brenda Dervin's Sense-Making Methodology:What Has Been Achieved and Why It Matters Now?
No full textBrenda Dervin made a tremendous contribution to both the fields of communication and information science through her Sense-Making Methodology. She was one of the first to advocate for a user-centered perspective in the field and had a tremendous impact on generations of researchers across various disciplines. Almost three years after her passing in December 2022, this panel brings together a diverse range of speakers to celebrate Dervin's contribution to ASIS&T and to information science. This highly interactive panel will cover various topics ranging from interactions with Dervin to the use of Dervin's SMM in theory, research, practice, human interaction, and artificial intelligence tools. The panel members have either engaged with Dervin the person, with her Sense-Making Methodology, or both. The session hopes to inspire the audience to use Dervin's Sense-Making Methodology (SMM) in their research and practice.</p