767 research outputs found

    SEM-EDS and water chemistry characteristics at the early stages of glacier recession reveal biogeochemical coupling between proglacial sediments and meltwater

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    Most glaciers worldwide are undergoing climate-forced recession, but the impact of glacier changes on biogeochemical cycles is unclear. This study examines the influence of proglacial sediment weathering on meltwater chemistry at the early stages of glacier recession in the High Arctic of Svalbard. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) in combination with a wide range of geochemical analyses were used in this study. The SEM-EDS analyses of sediments collected in front of Werenskioldbreen show general degradation of pyrite and carbonate grains with age. The outer parts of pyrite grains have a gradual decrease in sulphur and gradual increase in iron oxides due to pyrite oxidation. This process was less advanced in the proglacial zone younger than 100 years compared to older sites such as the terminal moraine from the Little Ice Age. In both the proglacial zone and the terminal moraine, physical weathering of mineral grains, including formation of microcracks and microfractures, clearly enhanced pyrite oxidation. A consequence of proglacial sediment weathering is that the river chemistry is strongly affected by carbonate dissolution driven by sulphuric acid from sulphide oxidation. Also, reactive iron oxides, a product of sulphide oxidation, are mobilized in the proglacial zone. The results of this study show that proglacial weathering in the High Arctic of Svalbard is strongly coupled to river geochemistry, especially during the early stages of proglacial exposure after glacier recession

    Effets du remplacement de la farine de poisson par les termites (Macrotermes Sp.) sur l’evolution ponderale et les caracteristiques de carcasse de la volaille locale au Burkina Faso

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    The high cost and the accessibility of animal protein sources is a major issue in poultry farming in Burkina Faso. The present study aimed to assess the suitability of two termite species as feed for traditional chicken (Gallus domesticus) and guinea fowl (Numida meleagris), comparatively to commercial fishmeal available in this country. The study was carried out during eight weeks in Burkina Faso on ninety chickens and ninety guinea fowls, sixteen weeks old. Two termite species (dry Macrotermes subhyalinus and fresh Macrotermes bellicosus) and commercial fishmeal for poultry feed formulation that is available in the country were used as animal protein ingredients in three feeding management regimes. The birds were allocated to the three feeding treatments, with two replicates per treatment: i) treatment 1 (R1) with a diet including 2.5% of dried termites; ii) treatment 2 (R2) diet with no animal protein ingredient included, but with fresh termites given separately and the amount was depending on the daily capture; iii) treatment 3 (R3) diet including 2.5% of fishmeal. The results showed an average daily feed consumption of 65.5 g per bird. Average daily gain (ADG) for chickens was 7.7 g, 7.8 g and 7.5 g for treatment R1, R2 and R3, respectively. ADG for guinea fowl was 5.64g, 5.34 g and 5.35 g for R1, R2 and R3, respectively. Carcass characteristics studied on male guinea fowl showed a mean carcass percentage of 66.4%. Data on the taste and tenderness showed that R1 and R2 gave a better taste to guinea fowl meat, while R3 and R2 gave more tender meat. Average dry matter contents of the thighs were 42.4%, 41.8% and 40.6% for the groups R1, R2 and R3, respectively. No significant difference (p>0.05) was observed between treatments for all the parameters. Thus, dry and fresh Macrotermes spp. can be suitable animal protein ingredients that can substitute fishmeal in traditional chickens and guinea fowl feeding in rural area.Keywords: termites, fishmeal, feeding, local poultry, live weight performances, Burkina Fas

    Underperforming policy networks : the biopesticides network in the United Kingdom

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    Loosely integrated and incomplete policy networks have been neglected in the literature. They are important to consider in terms of understanding network underperformance. The effective delivery and formulation of policy requires networks that are not incomplete or underperforming. The biopesticides policy network in the United Kingdom is considered and its components identified with an emphasis on the lack of integration of retailers and environmental groups. The nature of the network constrains the actions of its agents and frustrates the achievement of policy goals. A study of this relatively immature policy network also allows for a focus on network formation. The state, via an external central government department, has been a key factor in the development of the network. Therefore, it is important to incorporate such factors more systematically into understandings of network formation. Feedback efforts from policy have increased interactions between productionist actors but the sphere of consumption remains insufficiently articulated

    Jatropha growth and oilseed production in Africa

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    Security governance and networks: New theoretical perspectives in transatlantic security

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    The end of the Cold War has not only witnessed the rise of new transnational threats such as terrorism, crime, proliferation and civil war; it has also seen the growing role of non-state actors in the provision of security in Europe and North America. Two concepts in particular have been used to describe these transformations: security governance and networks. However, the differences and potential theoretical utility of these two concepts for the study of contemporary security have so far been under-examined. This article seeks to address this gap. It proposes that security governance can help to explain the transformation of Cold War security structures, whereas network analysis is particularly useful for understanding the relations and interactions between public and private actors in the making and implementation of national and international security policies

    Epigenetic regulation of adult neural stem cells: implications for Alzheimer's disease.

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    Published onlineJournal ArticleResearch Support, Non-U.S. Gov'tReviewExperimental evidence has demonstrated that several aspects of adult neural stem cells (NSCs), including their quiescence, proliferation, fate specification and differentiation, are regulated by epigenetic mechanisms. These control the expression of specific sets of genes, often including those encoding for small non-coding RNAs, indicating a complex interplay between various epigenetic factors and cellular functions.Previous studies had indicated that in addition to the neuropathology in Alzheimer's disease (AD), plasticity-related changes are observed in brain areas with ongoing neurogenesis, like the hippocampus and subventricular zone. Given the role of stem cells e.g. in hippocampal functions like cognition, and given their potential for brain repair, we here review the epigenetic mechanisms relevant for NSCs and AD etiology. Understanding the molecular mechanisms involved in the epigenetic regulation of adult NSCs will advance our knowledge on the role of adult neurogenesis in degeneration and possibly regeneration in the AD brain.Internationale Stichting Alzheimer Onderzoek (ISAO)Netherlands Organization for Scientific Research (NWO)Maastricht University Medical Centre 

    Finding the Area of Origin of the Horse-Chestnut Leaf Miner : a Challenge

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    CABI Bioscience Switzerland centreTechnological Educational Institution of KavalaInstitute of Animal EcologyUniversity pf Natural Resources and Applied Life Sciences, Institute of Plant ProtectionUniversity of SopronInstitute of ZoologyInstitute of Organic Chemistry and BiochemistryUniversity of ForestryProceedings : IUFRO Kanazawa 2003 "Forest Insect Population Dynamics and Host Influences"., Scedule:1419 September 2003, Vemue: Kanazawa Citymonde Hotel, Kanazawa, Japan, Joint metting of IUFRO working groups : 7.01.02 Tree resistance to Insects | 7.03.06 Integrated management of forset defoloating insects | 7.03.07 Population dynamics of forest insects, Sponsored by: IUFRO-J | Ishikawa Prefecture | Kanazawa City | 21st-COE Program of Kanazawa University, Editors: Kamata, Naoto | Liebhold, Nadrew M. | Quiring, Dan T. | Clancy, Karen M

    Essential versus accessory aspects of cell death: recommendations of the NCCD 2015

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    Cells exposed to extreme physicochemical or mechanical stimuli die in an uncontrollable manner, as a result of their immediate structural breakdown. Such an unavoidable variant of cellular demise is generally referred to as ‘accidental cell death’ (ACD). In most settings, however, cell death is initiated by a genetically encoded apparatus, correlating with the fact that its course can be altered by pharmacologic or genetic interventions. ‘Regulated cell death’ (RCD) can occur as part of physiologic programs or can be activated once adaptive responses to perturbations of the extracellular or intracellular microenvironment fail. The biochemical phenomena that accompany RCD may be harnessed to classify it into a few subtypes, which often (but not always) exhibit stereotyped morphologic features. Nonetheless, efficiently inhibiting the processes that are commonly thought to cause RCD, such as the activation of executioner caspases in the course of apoptosis, does not exert true cytoprotective effects in the mammalian system, but simply alters the kinetics of cellular demise as it shifts its morphologic and biochemical correlates. Conversely, bona fide cytoprotection can be achieved by inhibiting the transduction of lethal signals in the early phases of the process, when adaptive responses are still operational. Thus, the mechanisms that truly execute RCD may be less understood, less inhibitable and perhaps more homogeneous than previously thought. Here, the Nomenclature Committee on Cell Death formulates a set of recommendations to help scientists and researchers to discriminate between essential and accessory aspects of cell death

    Frontiers, Opportunities, and Challenges in Biochemical and Chemical Catalysis of CO_2 Fixation

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    Two major energy-related problems confront the world in the next 50 years. First, increased worldwide competition for gradually depleting fossil fuel reserves (derived from past photosynthesis) will lead to higher costs, both monetarily and politically. Second, atmospheric CO_2 levels are at their highest recorded level since records began. Further increases are predicted to produce large and uncontrollable impacts on the world climate. These projected impacts extend beyond climate to ocean acidification, because the ocean is a major sink for atmospheric CO2.1 Providing a future energy supply that is secure and CO_2-neutral will require switching to nonfossil energy sources such as wind, solar, nuclear, and geothermal energy and developing methods for transforming the energy produced by these new sources into forms that can be stored, transported, and used upon demand
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