Browsing by Subject "STORAGE"

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  • Seppä, Laila Elisabet; Tahvonen, Risto; Tuorila, Hely Margareetta (2016)
  • Abbott, Benjamin W.; Jones, Jeremy B.; Schuur, Edward A. G.; Chapin, F. Stuart; Bowden, William B.; Bret-Harte, M. Syndonia; Epstein, Howard E.; Flannigan, Michael D.; Harms, Tamara K.; Hollingsworth, Teresa N.; Mack, Michelle C.; McGuire, A. David; Natali, Susan M.; Rocha, Adrian V.; Tank, Suzanne E.; Turetsky, Merritt R.; Vonk, Jorien E.; Wickland, Kimberly P.; Aiken, George R.; Alexander, Heather D.; Amon, Rainer M. W.; Benscoter, Brian W.; Bergeron, Yves; Bishop, Kevin; Blarquez, Olivier; Bond-Lamberty, Ben; Breen, Amy L.; Buffam, Ishi; Cai, Yihua; Carcaillet, Christopher; Carey, Sean K.; Chen, Jing M.; Chen, Han Y. H.; Christensen, Torben R.; Cooper, Lee W.; Cornelissen, J. Hans C.; de Groot, William J.; DeLuca, Thomas H.; Dorrepaal, Ellen; Fetcher, Ned; Finlay, Jacques C.; Forbes, Bruce C.; French, Nancy H. F.; Gauthier, Sylvie; Girardin, Martin P.; Goetz, Scott J.; Goldammer, Johann G.; Gough, Laura; Grogan, Paul; Guo, Laodong; Higuera, Philip E.; Hinzman, Larry; Hu, Feng Sheng; Hugelius, Gustaf; Jafarov, Elchin E.; Jandt, Randi; Johnstone, Jill F.; Karlsson, Jan; Kasischke, Eric S.; Kattner, Gerhard; Kelly, Ryan; Keuper, Frida; Kling, George W.; Kortelainen, Pirkko; Kouki, Jari; Kuhry, Peter; Laudon, Hjalmar; Laurion, Isabelle; Macdonald, Robie W.; Mann, Paul J.; Martikainen, Pertti J.; McClelland, James W.; Molau, Ulf; Oberbauer, Steven F.; Olefeldt, David; Pare, David; Parisien, Marc-Andre; Payette, Serge; Peng, Changhui; Pokrovsky, Oleg S.; Rastetter, Edward B.; Raymond, Peter A.; Raynolds, Martha K.; Rein, Guillermo; Reynolds, James F.; Robards, Martin; Rogers, Brendan M.; Schaedel, Christina; Schaefer, Kevin; Schmidt, Inger K.; Shvidenko, Anatoly; Sky, Jasper; Spencer, Robert G. M.; Starr, Gregory; Striegl, Robert G.; Teisserenc, Roman; Tranvik, Lars J.; Virtanen, Tarmo; Welker, Jeffrey M.; Zimov, Sergei (2016)
    As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%-85% of permafrost carbon release can still be avoided if human emissions are actively reduced.
  • Gora, Evan M.; Kneale, Riley C.; Larjavaara, Markku; Muller-Landau, Helene C. (2019)
    Woody debris (WD) stocks and fluxes are important components of forest carbon budgets and yet remain understudied, particularly in tropical forests. Here we present the most comprehensive assessment of WD stocks and fluxes yet conducted in a tropical forest, including one of the first tropical estimates of suspended WD. We rely on data collected over 8 years in an old-growth moist tropical forest in Panama to quantify spatiotemporal variability and estimate minimum sample sizes for different components. Downed WD constituted the majority of total WD mass (78%), standing WD contributed a substantial minority (21%), and suspended WD was the smallest component (1%). However, when considering sections of downed WD that are elevated above the soil, the majority of WD inputs and approximately 50% of WD stocks were disconnected from the forest floor. Branchfall and liana wood accounted for 17 and 2% of downed WD, respectively. Residence times averaged 1.9 years for standing coarse WD (CWD; > 20 cm diameter) and 3.6 years for downed CWD. WD stocks and inputs were highly spatially variable, such that the sampling efforts necessary to estimate true values within 10% with 95% confidence were > 130 km of transects for downed CWD and > 550 ha area for standing CWD. The vast majority of studies involve much lower sampling efforts, suggesting that considerably more data are required to precisely quantify tropical forest WD pools and fluxes. The demonstrated importance of elevated WD in our study indicates a need to understand how elevation above the ground alters decomposition rates and incorporate this understanding into models of forest carbon cycling.
  • Maarala, Altti Ilari; Arasalo, Ossi; Valenzuela, Daniel; Mäkinen, Veli; Heljanko, Keijo (2021)
    Computational pan-genomics utilizes information from multiple individual genomes in large-scale comparative analysis. Genetic variation between case-controls, ethnic groups, or species can be discovered thoroughly using pan-genomes of such subpopulations. Whole-genome sequencing (WGS) data volumes are growing rapidly, making genomic data compression and indexing methods very important. Despite current space-efficient repetitive sequence compression and indexing methods, the deployed compression methods are often sequential, computationally time-consuming, and do not provide efficient sequence alignment performance on vast collections of genomes such as pan-genomes. For performing rapid analytics with the ever-growing genomics data, data compression and indexing methods have to exploit distributed and parallel computing more efficiently. Instead of strict genome data compression methods, we will focus on the efficient construction of a compressed index for pan-genomes. Compressed hybrid-index enables fast sequence alignments to several genomes at once while shrinking the index size significantly compared to traditional indexes. We propose a scalable distributed compressed hybrid-indexing method for large genomic data sets enabling pan-genome-based sequence search and read alignment capabilities. We show the scalability of our tool, DHPGIndex, by executing experiments in a distributed Apache Spark-based computing cluster comprising 448 cores distributed over 26 nodes. The experiments have been performed both with human and bacterial genomes. DHPGIndex built a BLAST index for n = 250 human pan-genome with an 870:1 compression ratio (CR) in 342 minutes and a Bowtie2 index with 157:1 CR in 397 minutes. For n = 1,000 human pan-genome, the BLAST index was built in 1520 minutes with 532:1 CR and the Bowtie2 index in 1938 minutes with 76:1 CR. Bowtie2 aligned 14.6 GB of paired-end reads to the compressed (n = 1,000) index in 31.7 minutes on a single node. Compressing n = 13,375,031 (488 GB) GenBank database to BLAST index resulted in CR of 62:1 in 575 minutes. BLASTing 189,864 Crispr-Cas9 gRNA target sequences (23 MB in total) to the compressed index of human pan-genome (n = 1,000) finished in 45 minutes on a single node. 30 MB mixed bacterial sequences were (n = 599) were blasted to the compressed index of 488 GB GenBank database (n = 13,375,031) in 26 minutes on 25 nodes. 78 MB mixed sequences (n = 4,167) were blasted to the compressed index of 18 GB E. coli sequence database (n = 745,409) in 5.4 minutes on a single node.
  • Kemppinen, Julia; Niittynen, Pekka; Virkkala, Anna-Maria; Happonen, Konsta; Riihimäki, Henri; Aalto, Juha; Luoto, Miska (2021)
    In the tundra, woody plants are dispersing towards higher latitudes and altitudes due to increasingly favourable climatic conditions. The coverage and height of woody plants are increasing, which may influence the soils of the tundra ecosystem. Here, we use structural equation modelling to analyse 171 study plots and to examine if the coverage and height of woody plants affect the growing-season topsoil moisture and temperature (< 10 cm) as well as soil organic carbon stocks (< 80 cm). In our study setting, we consider the hierarchy of the ecosystem by controlling for other factors, such as topography, wintertime snow depth and the overall plant coverage that potentially influence woody plants and soil properties in this dwarf shrub-dominated landscape in northern Fennoscandia. We found strong links from topography to both vegetation and soil. Further, we found that woody plants influence multiple soil properties: the dominance of woody plants inversely correlated with soil moisture, soil temperature, and soil organic carbon stocks (standardised regression coefficients = - 0.39; - 0.22; - 0.34, respectively), even when controlling for other landscape features. Our results indicate that the dominance of dwarf shrubs may lead to soils that are drier, colder, and contain less organic carbon. Thus, there are multiple mechanisms through which woody plants may influence tundra soils.
  • Loisel, J.; Loisel, J.; Amesbury, Matthew J.; Magnan, G.; Anshari, G.; Beilman, D. W.; Benavides, J. C.; Blewett, J.; Camill, P.; Charman, D. J.; Chawchai, S.; Hedgpeth, A.; Kleinen, T.; Korhola, Atte; Large, D.; Mansilla, C. A.; Muller, J.; van Bellen, S.; West, J. B.; Yu, Z.; Bubier, J. L.; Garneau, M.; Moore, T.; Sannel, A. B. K.; Page, S.; Väliranta, Minna; Bechtold, M.; Brovkin, Victor; Cole, L. E. S.; Chanton, J. P.; Christensen, T. R.; Davies, M. A.; De Vleeschouwer, F.; Finkelstein, S. A.; Frolking, S.; Galka, M.; Gandois, L.; Girkin, N.; Harris, L.; Heinemeyer, A.; Hoyt, A. M.; Jones, M. C.; Joos, F.; Juutinen, Sari; Kaiser, K.; Lacourse, T.; Lamentowicz, M.; Larmola, T.; Leifeld, J.; Lohila, Annalea Katriina; Milner, A. M.; Minkkinen, Kari; Moss, P.; Naafs, B. D. A.; Nichols, J.; O'Donnell, J.; Payne, R.; Philben, M.; Piilo, Sanna; Quillet, A.; Ratnayake, A. S.; Roland, T. P.; Sjogersten, S.; Sonnentag, O.; Swindles, G. T.; Swinnen, W.; Talbot, J.; Treat, C.; Valach, A. C.; Wu, J. (2021)
    Peatlands are impacted by climate and land-use changes, with feedback to warming by acting as either sources or sinks of carbon. Expert elicitation combined with literature review reveals key drivers of change that alter peatland carbon dynamics, with implications for improving models. The carbon balance of peatlands is predicted to shift from a sink to a source this century. However, peatland ecosystems are still omitted from the main Earth system models that are used for future climate change projections, and they are not considered in integrated assessment models that are used in impact and mitigation studies. By using evidence synthesized from the literature and an expert elicitation, we define and quantify the leading drivers of change that have impacted peatland carbon stocks during the Holocene and predict their effect during this century and in the far future. We also identify uncertainties and knowledge gaps in the scientific community and provide insight towards better integration of peatlands into modelling frameworks. Given the importance of the contribution by peatlands to the global carbon cycle, this study shows that peatland science is a critical research area and that we still have a long way to go to fully understand the peatland-carbon-climate nexus.
  • Cuni-Sanchez, Aida; Sullivan, Martin J. P.; Platts, Philip J.; Lewis, Simon L.; Marchant, Rob; Imani, Gerard; Hubau, Wannes; Abiem, Iveren; Adhikari, Hari; Albrecht, Tomas; Altman, Jan; Amani, Christian; Aneseyee, Abreham B.; Avitabile, Valerio; Banin, Lindsay; Batumike, Rodrigue; Bauters, Marijn; Beeckman, Hans; Begne, Serge K.; Bennett, Amy C.; Bitariho, Robert; Boeckx, Pascal; Bogaert, Jan; Braeuning, Achim; Bulonvu, Franklin; Burgess, Neil D.; Calders, Kim; Chapman, Colin; Chapman, Hazel; Comiskey, James; de Haulleville, Thales; Decuyper, Mathieu; DeVries, Ben; Dolezal, Jiri; Droissart, Vincent; Ewango, Corneille; Feyera, Senbeta; Gebrekirstos, Aster; Gereau, Roy; Gilpin, Martin; Hakizimana, Dismas; Hall, Jefferson; Hamilton, Alan; Hardy, Olivier; Hart, Terese; Heiskanen, Janne; Hemp, Andreas; Herold, Martin; Hiltner, Ulrike; Horak, David; Kamdem, Marie-Noel; Kayijamahe, Charles; Kenfack, David; Kinyanjui, Mwangi J.; Klein, Julia; Lisingo, Janvier; Lovett, Jon; Lung, Mark; Makana, Jean-Remy; Malhi, Yadvinder; Martin, Emanuel H.; Mitchard, Edward T. A.; Morel, Alexandra; Mukendi, John T.; Muller, Tom; Nchu, Felix; Nyirambangutse, Brigitte; Okello, Joseph; Peh, Kelvin S. -H.; Pellikka, Petri; Phillips, Oliver L.; Plumptre, Andrew; Qie, Lan; Rovero, Francesco; Sainge, Moses N.; Schmitt, Christine B.; Sedlacek, Ondrej; Ngute, Alain S. K.; Sheil, Douglas; Sheleme, Demisse; Simegn, Tibebu Y.; Simo-Droissart, Murielle; Sonke, Bonaventure; Soromessa, Teshome; Sunderland, Terry; Svoboda, Miroslav; Taedoumg, Hermann; Taplin, James; Thomas, Sean C.; Timberlake, Jonathan; Tuagben, Darlington; Umunay, Peter; Uzabaho, Eustrate; Verbeeck, Hans; Vleminckx, Jason; Wallin, Goran; Wheeler, Charlotte; Willcock, Simon; Woods, John T.; Zibera, Etienne (2021)
    Tropical forests store 40-50 per cent of terrestrial vegetation carbon(1). However, spatial variations in aboveground live tree biomass carbon (AGC) stocks remain poorly understood, in particular in tropical montane forests(2). Owing to climatic and soil changes with increasing elevation(3), AGC stocks are lower in tropical montane forests compared with lowland forests(2). Here we assemble and analyse a dataset of structurally intact old-growth forests (AfriMont) spanning 44 montane sites in 12 African countries. We find that montane sites in the AfriMont plot network have a mean AGC stock of 149.4 megagrams of carbon per hectare (95% confidence interval 137.1-164.2), which is comparable to lowland forests in the African Tropical Rainforest Observation Network(4) and about 70 per cent and 32 per cent higher than averages from plot networks in montane(2,5,6) and lowland(7) forests in the Neotropics, respectively. Notably, our results are two-thirds higher than the Intergovernmental Panel on Climate Change default values for these forests in Africa(8). We find that the low stem density and high abundance of large trees of African lowland forests(4) is mirrored in the montane forests sampled. This carbon store is endangered: we estimate that 0.8 million hectares of old-growth African montane forest have been lost since 2000. We provide country-specific montane forest AGC stock estimates modelled from our plot network to help to guide forest conservation and reforestation interventions. Our findings highlight the need for conserving these biodiverse(9,10) and carbon-rich ecosystems. The aboveground carbon stock of a montane African forest network is comparable to that of a lowland African forest network and two-thirds higher than default values for these montane forests.
  • Kittler, Fanny; Burjack, Ina; Corradi, Chiara A. R.; Heimann, Martin; Kolle, Olaf; Merbold, Lutz; Zimov, Nikita; Zimov, Sergey; Gockede, Mathias (2016)
    Hydrologic conditions are a major controlling factor for carbon exchange processes in high-latitude ecosystems. The presence or absence of water-logged conditions can lead to significant shifts in ecosystem structure and carbon cycle processes. In this study, we compared growing season CO2 fluxes of a wet tussock tundra ecosystem from an area affected by decadal drainage to an undisturbed area on the Kolyma floodplain in northeastern Siberia. For this comparison we found the sink strength for CO2 in recent years (2013-2015) to be systematically reduced within the drained area, with a minor increase in photosynthetic uptake due to a higher abundance of shrubs outweighed by a more pronounced increase in respiration due to warmer near-surface soil layers. Still, in comparison to the strong reduction of fluxes immediately following the drainage disturbance in 2005, recent CO2 exchange with the atmosphere over this disturbed part of the tundra indicate a higher carbon turnover, and a seasonal amplitude that is comparable again to that within the control section. This indicates that the local permafrost ecosystem is capable of adapting to significantly different hydrologic conditions without losing its capacity to act as a net sink for CO2 over the growing season. The comparison of undisturbed CO2 flux rates from 2013-2015 to the period of 2002-2004 indicates that CO2 exchange with the atmosphere was intensified, with increased component fluxes (ecosystem respiration and gross primary production) over the past decade. Net changes in CO2 fluxes are dominated by a major increase in photosynthetic uptake, resulting in a stronger CO2 sink in 2013-2015. Application of a MODIS-based classification scheme to separate the growing season into four sub-seasons improved the interpretation of interannual variability by illustrating the systematic shifts in CO2 uptake patterns that have occurred in this ecosystem over the past 10 years and highlighting the important role of the late growing season for net CO2 flux budgets.
  • Tuderman, Anna-Kaisa; Strachan, Clare J.; Juppo, Anne M. (2018)
    The purpose of this research was to study isomalt as a protein-stabilizing excipient with lactate dehydrogenase (LDH) during freeze-drying and subsequent storage and compare it to sucrose, a standard freeze-drying excipient. Four different diastereomer mixtures of isomalt were studied. The stability of the protein was studied with a spectrophotometric enzyme activity test and circular dichroism after freeze-drying and after 21 days of storage at 16% RH. Physical stability was analyzed with differential scanning calorimetry and Karl Fischer titration. Statistical analysis was utilized in result analysis. LDH activity was almost completely retained after freeze-drying with sucrose; whereas samples stabilized with isomalt diastereomer mixtures had a considerably lower protein activity. During storage the sucrose-containing samples lost most of their enzymatic activity, while the isomalt mixtures retained the protein activity better. In all cases changes to protein secondary structure were observed. Isomalt diastereomer mixtures have some potential as protein-stabilizing excipients during freeze-drying and subsequent storage. Isomalt stabilized LDH moderately during freeze-drying; however it performed better during storage. Future studies with other proteins are required to evaluate more generally whether isomalt would be a suitable excipient for pharmaceutical freeze-dried protein formulations.
  • Li, Tong; Braud, Tristan; Li, Yong; Hui, Pan (2021)
    The current explosion of video traffic compels service providers to deploy caches at edge networks. Nowadays, most caching systems store data with a high programming voltage corresponding to the largest possible ‘expiry date’, typically on the order of years, which maximizes the cache damage. However, popular videos rarely exhibit lifecycles longer than a couple of months. Consequently, the programming voltage can instead be adapted to fit the lifecycle and mitigate the cache damage accordingly. In this paper, we propose LiA-cache, a Lifecycle-Aware caching policy for online videos. LiA-cache finds both near-optimal caching retention times and cache eviction policies by optimizing traffic delivery cost and cache damage cost conjointly. We first investigate temporal patterns of video access from a real-world dataset covering 10 million online videos collected by one of the largest mobile network operators in the world. We next cluster the videos based on their access lifecycles and integrate the clustering into a general model of the caching system. Specifically, LiA-cache analyzes videos and caches them depending on their cluster label. Compared to other popular policies in real-world scenarios, LiA-cache can reduce cache damage up to 90%, while keeping a cache hit ratio close to a policy purely relying on video popularity.
  • Norri, Tuukka; Cazaux, Bastien; Kosolobov, Dmitry; Mäkinen, Veli (2019)
    Background: We study a preprocessing routine relevant in pan-genomic analyses: consider a set of aligned haplotype sequences of complete human chromosomes. Due to the enormous size of such data, one would like to represent this input set with a few founder sequences that retain as well as possible the contiguities of the original sequences. Such a smaller set gives a scalable way to exploit pan-genomic information in further analyses (e.g. read alignment and variant calling). Optimizing the founder set is an NP-hard problem, but there is a segmentation formulation that can be solved in polynomial time, defined as follows. Given a threshold L and a set R={R1,...,Rm} of m strings (haplotype sequences), each having length n, the minimum segmentation problem for founder reconstruction is to partition [1,n] into set P of disjoint segments such that each segment [a,b]P has length at least L and the number d(a,b)=|{Ri[a,b]:1im}| of distinct substrings at segment [a,b] is minimized over [a,b]P. The distinct substrings in the segments represent founder blocks that can be concatenated to form max{d(a,b):[a,b]P} founder sequences representing the original R such that crossovers happen only at segment boundaries. Results: We give an O(mn) time (i.e. linear time in the input size) algorithm to solve the minimum segmentation problem for founder reconstruction, improving over an earlier O(mn2). Conclusions: Our improvement enables to apply the formulation on an input of thousands of complete human chromosomes. We implemented the new algorithm and give experimental evidence on its practicality. The implementation is available in
  • Belazzougui, Djamal; Cunial, Fabio; Karkkainen, Juha; Makinen, Veli (2020)
    The field of succinct data structures has flourished over the past 16 years. Starting from the compressed suffix array by Grossi and Vitter (STOC 2000) and the FM-index by Ferragina and Manzini (FOCS 2000), a number of generalizations and applications of string indexes based on the Burrows-Wheeler transform (BWT) have been developed, all taking an amount of space that is close to the input size in bits. In many large-scale applications, the construction of the index and its usage need to be considered as one unit of computation. For example, one can compare two genomes by building a common index for their concatenation and by detecting common substructures by querying the index. Efficient string indexing and analysis in small space lies also at the core of a number of primitives in the data-intensive field of high-throughput DNA sequencing. We report the following advances in string indexing and analysis: We show that the BWT of a string T is an element of {1, . . . , sigma}(n) can be built in deterministic O(n) time using just O(n log sigma) bits of space, where sigma We also show how to build many of the existing indexes based on the BWT, such as the compressed suffix array, the compressed suffix tree, and the bidirectional BWT index, in randomized O(n) time and in O(n log sigma) bits of space. The previously fastest construction algorithms for BWT, compressed suffix array and compressed suffix tree, which used O(n log sigma) bits of space, took O(n log log sigma) time for the first two structures and O(n log(epsilon) n) time for the third, where. is any positive constant smaller than one. Alternatively, the BWT could be previously built in linear time if one was willing to spend O(n log sigma log log(sigma) n) bits of space. Contrary to the state-of-the-art, our bidirectional BWT index supports every operation in constant time per element in its output.
  • Yang, Zhen; Piironen, Vieno Irene; Lampi, Anna-Maija (2017)
    The aim was to study lipase, lipoxygenase (LOX) and peroxygenase (PDX) activities in oat and faba bean samples to be able to evaluate their potential in formation of lipid-derived off-flavours. Lipase and LOX activities were measured by spectroscopy, and PDX activities via the formation of epoxides. An ultra-high performance liquid chromatography method was developed to study the formation of fatty acid epoxides. The epoxides of esters were measured by gas chromatography. Mass spectroscopy was used to verify the identity of the epoxides. Both oat and faba bean possessed high lipase activities. In faba bean, LOX catalysed the formation of hydroperoxides, whose break-down products are the likely cause of off-flavours. Since oat had low LOX activity, autoxidation is needed to initiate lipid oxidation. Oat had high PDX activity, which is able to convert hydroperoxides to epoxy and hydroxy fatty acids that could contribute significantly to off-flavours. PDX activity in the faba bean was low. Thus, in faba bean volatile lipid oxidation products could rapidly be formed by LOX, whereas in oat reactions are slower due to the need of autoxidation prior to further reactions.
  • Vesakoski, Jenni-Mari; Alho, Petteri; Hyyppa, Juha; Holopainen, Markus; Flener, Claude; Hyyppa, Hannu (2014)
  • Zhang, Yuemei; Ertbjerg, Per (2019)
    The role of protein denaturation in formation of thaw loss is currently not well understood. This study investigated denaturation of myofibrillar and sarcoplasmic proteins of pork loins caused by freezing-thawing in relation to freezing rate. Compared to fast freezing, slow freezing caused 28% larger thaw loss, decreased water-holding capacity of myofibrils and increased surface hydrophobicity, indicating more pronounced denaturation of myofibrillar proteins. We here propose a model: In slow freezing protons are concentrated in the unfrozen water resulting in reduced pH in proximity of structural proteins causing protein denaturation. In parallel, large ice crystals are formed outside of muscle fibers resulting in transversal shrinkage. In fast freezing small ice crystals trap protons and cause less severe protein denaturation and reduced thaw loss. Differential scanning calorimetry and tryptophan fluorescence spectra indicated sarcoplasmic protein denaturation in drip due to freezing-thawing. However, sarcoplasmic protein denaturation was independent of freezing rate.
  • Muster, Sina; Roth, Kurt; Langer, Moritz; Lange, Stephan; Aleina, Fabio Cresto; Bartsch, Annett; Morgenstern, Anne; Grosse, Guido; Jones, Benjamin; Sannel, A. Britta K.; Sjoberg, Ylva; Guenther, Frank; Andresen, Christian; Veremeeva, Alexandra; Lindgren, Prajna R.; Bouchard, Frederic; Lara, Mark J.; Fortier, Daniel; Charbonneau, Simon; Virtanen, Tarmo A.; Hugelius, Gustaf; Palmtag, Juri; Siewert, Matthias B.; Riley, William J.; Koven, Charles D.; Boike, Julia (2017)
    Ponds and lakes are abundant in Arctic permafrost lowlands. They play an important role in Arctic wetland ecosystems by regulating carbon, water, and energy fluxes and providing freshwater habitats. However, ponds, i. e., waterbodies with surface areas smaller than 1.0 x 10(4) m(2), have not been inventoried on global and regional scales. The Permafrost Region Pond and Lake (PeRL) database presents the results of a circum-Arctic effort to map ponds and lakes from modern (2002-2013) high-resolution aerial and satellite imagery with a resolution of 5m or better. The database also includes historical imagery from 1948 to 1965 with a resolution of 6m or better. PeRL includes 69 maps covering a wide range of environmental conditions from tundra to boreal regions and from continuous to discontinuous permafrost zones. Waterbody maps are linked to regional permafrost landscape maps which provide information on permafrost extent, ground ice volume, geology, and lithology. This paper describes waterbody classification and accuracy, and presents statistics of waterbody distribution for each site. Maps of permafrost landscapes in Alaska, Canada, and Russia are used to extrapolate waterbody statistics from the site level to regional landscape units. PeRL presents pond and lake estimates for a total area of 1.4 x 10(6) km(2) across the Arctic, about 17% of the Arctic lowland (
  • Adamczyk, Bartosz; Sietio, Outi-Maaria; Strakova, Petra; Prommer, Judith; Wild, Birgit; Hagner, Marleena; Pihlatie, Mari; Fritze, Hannu; Richter, Andreas; Heinonsalo, Jussi (2019)
    Boreal forests are ecosystems with low nitrogen (N) availability that store globally significant amounts of carbon (C), mainly in plant biomass and soil organic matter (SOM). Although crucial for future climate change predictions, the mechanisms controlling boreal C and N pools are not well understood. Here, using a three-year field experiment, we compare SOM decomposition and stabilization in the presence of roots, with exclusion of roots but presence of fungal hyphae and with exclusion of both roots and fungal hyphae. Roots accelerate SOM decomposition compared to the root exclusion treatments, but also promote a different soil N economy with higher concentrations of organic soil N compared to inorganic soil N accompanied with the build-up of stable SOM-N. In contrast, root exclusion leads to an inorganic soil N economy (i.e., high level of inorganic N) with reduced stable SOM-N buildup. Based on our findings, we provide a framework on how plant roots affect SOM decomposition and stabilization.
  • Räsänen, Tuomas; Juutinen, Sari; Aurela, Mika; Virtanen, Tarmo (2019)
    Remote sensing based biomass estimates in Arctic areas are usually produced using coarse spatial resolution satellite imagery, which is incapable of capturing the fragmented nature of tundra vegetation communities. We mapped aboveground biomass using field sampling and very high spatial resolution (VHSR) satellite images (QuickBird, WorldView-2 and WorldView-3) in four different Arctic tundra or peatland sites with low vegetation located in Russia, Canada, and Finland. We compared site-specific and cross-site empirical regressions. First, we classified species into plant functional types and estimated biomass using easy, non-destructive field measurements (cover, height). Second, we used the cover/height-based biomass as the response variable and used combinations of single bands and vegetation indices in predicting total biomass. We found that plant functional type biomass could be predicted reasonably well in most cases using cover and height as the explanatory variables (adjusted R-2 0.21-0.92), and there was considerable variation in the model fit when the total biomass was predicted with satellite spectra (adjusted R-2 0.33-0.75). There were dissimilarities between cross-site and site-specific regression estimates in satellite spectra based regressions suggesting that the same regression should be used only in areas with similar kinds of vegetation. We discuss the considerable variation in biomass and plant functional type composition within and between different Arctic landscapes and how well this variation can be reproduced using VHSR satellite images. Overall, the usage of VHSR images creates new possibilities but to utilize them to full potential requires similarly more detailed in-situ data related to biomass inventories and other ecosystem change studies and modelling.
  • Göbüz, Göker; Liu, Chang; Jiang, Zhong-qing; Pulkkinen, Marjo; Piironen, Vieno; Sontag-Strohm, Tuula; Heinonen, Marina (2018)
    The course of protein-lipid co-oxidation was investigated in oil-in-water emulsions stabilized with proteins extracted from microwave-treated (MWT) and conventional thermal-treated (CTT) faba beans stored at 37 degrees C for 7days. Emulsions prepared with proteins from untreated (UT) faba beans and soy protein isolate (SP) were monitored for comparison. Lipid oxidation was detected through formation of primary and secondary oxidation products while protein oxidation was examined via tryptophan fluorescence degradation in interface and aqueous phase. Oxidation of proteins was more emphasized in the interfacial layers of MWT, CTT, and SP emulsions than in UT emulsions due to the prominence of radical chain-driven co-oxidation mechanism while lipoxygenase (LOX) activity in UT and MWT emulsions resulted in high amounts of hydroperoxides and abundance in lipid oxidation volatiles. Conventional thermal treatment provided better oxidative stability than microwave treatment reflected in lower levels of hydroperoxides and relative lack of diversity in lipid volatiles. Among detected volatiles, formation of ketones was more distinguished in MWT, CTT, and SP emulsions while UT emulsions contained a more diverse range of alkenals and alkanals. Ketones are known to form mainly through radical recombination reactions which combined with the results of protein oxidation supports that radical transfer reactions between proteins and lipids were the driving force behind oxidation in MWT, CTT, and SP emulsions. Treatments of faba beans resulted in increased oxidative stability of emulsified lipids and lower degradation of aqueous phase proteins.
  • Tamene, Aynadis; Kariluoto, Susanna; Baye, Kaleab; Humblot, Christele (2019)
    Injera is an Ethiopian fermented flatbread preferably made from whole grain cereal (tef). Tef it is increasingly used to produce gluten-free pasta and bread, but the folate content of teff and products made from it remains unknown. Given that folate deficiencies lead to several health disorders, the aim of this study was to quantify folate in each of the three main steps of traditional processing of tef injera. Total folate contents of tef flour, fermented batter and injera were determined through microbiological assays using Lactobacillus rhamnosus (ATCC 7469). Folate content of tef flour was 8.7 mu g/100 g of dry matter content, which is in the same range as the richest cereals like oats. The increase in folate content due to fermentation was highly variable (60-148%). Cooking always led to folate losses, with a maximum of 52.8%. Altogether, injera processing increased folate retention between 38.0 and 121.8%. Folate content of injera was 14.3 mu g/100 g on fresh weight-basis. Tef injera can contribute up to 10% of the recommended nutrient intake of folate for children aged 1-3 and women of reproductive age. Although the folate content of teff is already high, future studies should focus on optimizing the folate content of injera.