101 research outputs found
Surface energy exchange in pristine and managed boreal peatlands
Surface-atmosphere energy exchange is strongly ecosystem-specific. At the same time, as the energy balance constitutes responses of an ecosystem to environmental stressors including precipitation, humidity and solar radiation, it results in feedbacks of potential importance for the regional climate. Northern peatlands represent a diverse class of ecosystems that cover nearly 6 x 10(6) km(2) in the Boreal region, which makes the inter-comparison of their energy balances an important objective. With this in mind we studied energy exchange across a broad spectrum of peatlands from pristine fens and bogs to forested and agriculturally managed peatlands, which represent a large fraction of the landscape in Finland and Sweden. The effects of management activities on the energy balance were extensively examined from the micrometeorological point of view, using eddy covariance data from eight sites in these two countries (56 degrees 12'-62 degrees 11' N, 13 degrees 03'-30 degrees 05' E). It appears that the surface energy balance varies widely amongst the different peatland types. Generally, energy exchange features including the Bowen ratio, surface conductance, coupling to the atmosphere, responses to water table fluctuations and vapour pressure deficit could be associated directly with the peatland type. The relative constancy of the Bowen ratio in natural open mires contrasted with its variation in tree-covered and agricultural peatlands. We conclude that the impacts of management and the consequences of land-use change in peatlands for the local and regional climate might be substantial.Peer reviewe
Opportunities for an African greenhouse gas observation system
Global population projections foresee the biggest increase to occur in Africa with most of the available uncultivated land to ensure food security remaining on the continent. Simultaneously, greenhouse gas emissions are expected to rise due to ongoing land use change, industrialisation, and transport amongst other reasons with Africa becoming a major emitter of greenhouse gases globally. However, distinct knowledge on greenhouse gas emissions sources and sinks as well as their variability remains largely unknown caused by its vast size and diversity and an according lack of observations across the continent. Thus, an environmental research infrastructureâas being setup in other regionsâis more needed than ever. Here, we present the results of a design study that developed a blueprint for establishing such an environmental research infrastructure in Africa. The blueprint comprises an inventory of already existing observations, the spatial disaggregation of locations that will enable to reduce the uncertainty in climate forcingâs in Africa and globally as well as an overall estimated cost for such an endeavour of about 550 M⏠over the next 30 years. We further highlight the importance of the development of an e-infrastructure, the necessity for capacity development and the inclusion of all stakeholders to ensure African ownership
The Liganding of Glycolipid Transfer Protein Is Controlled by Glycolipid Acyl Structure
Glycosphingolipids (GSLs) play major roles in cellular growth and development. Mammalian glycolipid transfer proteins (GLTPs) are potential regulators of cell processes mediated by GSLs and display a unique architecture among lipid binding/transfer proteins. The GLTP fold represents a novel membrane targeting/interaction domain among peripheral proteins. Here we report crystal structures of human GLTP bound to GSLs of diverse acyl chain length, unsaturation, and sugar composition. Structural comparisons show a highly conserved anchoring of galactosyl- and lactosyl-amide headgroups by the GLTP recognition center. By contrast, acyl chain chemical structure and occupancy of the hydrophobic tunnel dictate partitioning between sphingosine-in and newly-observed sphingosine-out ligand-binding modes. The structural insights, combined with computed interaction propensity distributions, suggest a concerted sequence of events mediated by GLTP conformational changes during GSL transfer to and/or from membranes, as well as during GSL presentation and/or transfer to other proteins
Teaching introductory programming: a quantitative evaluation of different approaches
© ACM, 2014. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in ACM Transactions on Computing Education, 2014, Vol. 14, No. 4, Article 26, DOI: http://dx.doi.org/10.1145/266241
Molecular biological effects and toxicity of combustion aerosol emissions on air/liquid-interface exposed human and murine lung cells
Interactions between the atmosphere, cryosphere, and ecosystems at northern high latitudes
The Nordic Centre of Excellence CRAICC (CryosphereâAtmosphere Interactions
in a Changing Arctic Climate), funded by NordForsk in the years 2011â2016,
is the largest joint Nordic research and innovation initiative to date,
aiming to strengthen research and innovation regarding climate change issues
in the Nordic region. CRAICC gathered more than 100Â scientists from all
Nordic countries in a virtual centre with the objectives of identifying and
quantifying the major processes controlling Arctic warming and related feedback
mechanisms, outlining strategies to mitigate Arctic warming, and developing
Nordic Earth system modelling with a focus on short-lived climate
forcers (SLCFs), including natural and anthropogenic aerosols.
The outcome of CRAICC is reflected in more than 150Â peer-reviewed scientific
publications, most of which are in the CRAICC special issue of the journal
Atmospheric Chemistry and Physics. This paper presents an overview
of the main scientific topics investigated in the centre and provides the
reader with a state-of-the-art comprehensive summary of what has been achieved in
CRAICC with links to the particular publications for further detail. Faced
with a vast amount of scientific discovery, we do not claim to completely
summarize the results from CRAICC within this paper, but rather
concentrate here on the main results which are related to feedback loops in
climate changeâcryosphere interactions that affect Arctic amplification.</p
The production and turnover of extramatrical mycelium of ectomycorrhizal fungi in forest soils: role in carbon cycling
Mycorrhizal colonisation of highbush blueberry and its native relatives in central Finland
Transmission electromicroscopy, trypan blue staining in combination with stereomicroscope analysis and biochemical ergosterol assay were used to study the mycorrhizal symbionts in wild bilberry (Vaccinium myrtillus), bog whortleberry (Vaccinium uliginosum) and highbush blueberry (Vaccinium corymbosum) roots. TEM-analysis showed that in all species ericoid mycorrhizas formed hyphae coil inside the epidermal root cells. In stereomicroscopic viewing the highest mycorrhizal colonisation was observed in the roots of wild bilberries (51%), whereas according to the ergosterol assay the highest total fungal biomass of roots was found in bog whortleberries (209 mg g-1 of root d. wt). Both ergosterol and microscopical method showed that the mycorrhizal associations in blueberry cultivars and their wild relatives growing on natural soil medium are frequent, although ericoid mycorrhiza formation of highbush blueberries was somewhat weaker than that of wild bilberries and bog whortleberries.Viljellyn pensasmustikan (Vaccinium corymbosum) sekÀ luonnonvaraisten mustikan (Vaccinium myrtillus) ja juolukan (Vaccinium uliginosum) sienijuuria tutkittiin transmissioelektronimikroskoopilla (TEM), stereomikroskooppisesti trypaanisinisellÀ vÀrjÀtyistÀ juurista ja biokemiallisella ergosterolianalyysillÀ. Kaikilta tutkituilta lajeilta löytyi erikoidimykoritsoille tyypillisiÀ rihmastokiehkuroita juuren pintakerroksen soluista TEM-analyysissÀ. Stereomikroskooppianalyysin perusteella luonnonvaraisilla mustikoilla oli korkeimmat mykoritsainfektiot juurissaan (hiusjuurista 51 % infektoitunut), kun taas suurimmat ergosterolipitoisuudet olivat juolukoilla (ergosterolia 209 mg/g juurta). NÀiden tulosten perusteella voidaan sanoa, ettÀ mykoritsasymbioosit juurissa ovat yleisiÀ kaikilla tutkituilla Vaccinium-lajeilla, tosin viljellyillÀ pensasmustikoilla mykoritsainfektioiden mÀÀrÀ on luonnonvaraisia sukulaisiaan jonkin verran alempi
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