453 research outputs found

    Climatic Impact on Small Grain Production in the Subarctic Region of the United States

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    The Subarctic comprises the higher mid-latitudinal regions with short, cool, moist summers and long, cold, dry winters. Indeed, the short, cool growing season is often thought of as a barrier to crop growth and diversity in these regions. Little is known, however, concerning the impact of the Subarctic climate on crop production. This study aimed to identify the climatic factors that are most important to the production of small grains in the Subarctic region of Alaska. The impact of climate on 'Galt' and 'Weal' barley (Hordeum vulgare L.), 'Nip' and 'Toral' oat (Avena sativa L.), and 'Gasser' and 'Park' wheat (Triticum aestivum L.) was assessed using climate and grain yield data collected from 1972 to 1989 at Fairbanks. Multiple regression analysis was used to identify the climatic factors that most influence yield. Different factors accounted for the largest proportion of variability in yield across years for the different grains. 1) For barley, variations in precipitation deficit (pan evaporation minus precipitation) and distribution of precipitation events within a growing season accounted for 41% of the variability across years in yield of Galt and Weal cultivars. 2) For oat, variations in the precipitation deficit ratio (ratio between precipitation deficit and pan evaporation) accounted for 44% of the variability across years in yield of Nip and 58% in yield of Toral oat. 3) For wheat, variations in number of days between precipitation events within a growing season, precipitation deficit, and temperature explained 70% of the variability across years in yield of Gasser and Park wheat. Results from our analysis further indicated that small grain production was bolstered in seasons with greater precipitation, more frequent precipitation, or lower evaporative demand (pan evaporation). Only wheat production appeared to be favored by higher minimum air temperatures. This study suggests that, despite the cool growing season in interior Alaska, the primary climatic limitation to crop production is water stress, associated with low precipitation or high evaporative demand. Therefore, land management practices aimed at conserving soil water will likely bolster crop production in the Subarctic.Le Subarctique comprend l'extrême nord des latitudes moyennes où les étés sont courts, frais et humides et les hivers longs, froids et secs. En fait, on pense souvent que la brièveté et la fraîcheur de la saison de croissance sont des obstacles au développement et à la diversité des cultures dans ces régions. En revanche, on sait très peu de choses sur l'impact qu'a le climat subarctique sur la production végétale. Cette étude vise à déterminer les facteurs climatiques les plus importants pour la production des petites céréales dans la zone subarctique de l'Alaska. On a mesuré l'incidence du climat sur l'orge (Hordeum vulgare L.) "Galt" et "Weal", l'avoine (Avena sativa L.) "Nip" et "Toral" et le blé (Triticum aestivum L.) "Gasser" et "Park" en se servant de données sur le climat et le rendement recueillies à Fairbanks de 1972 à 1989. On a eu recours à l'analyse de régression multiple pour mettre en évidence les facteurs climatiques qui ont la plus grande influence sur le rendement. Au cours de toutes les années, la majeure partie de la variabilité dans le rendement des différentes céréales s'expliquait par plusieurs facteurs: 1) Pour l'orge, les variations dans le déficit de précipitations (évaporation du bac moins les précipitations) et la distribution des événements hyétométriques durant une saison de croissance comptaient pour 41 % de la variabilité au cours des années dans le rendement des cultivars Galt et Weal; 2) Pour l'avoine, les variations dans le rapport du déficit de précipitations (rapport entre le déficit de précipitations et l'évaporation du bac) comptaient pour 44 % de la variabilité au cours des années dans le rendement de l'avoine Nip et 58 % dans celui de l'avoine Toral; 3) Pour le blé, les variations du nombre de jours entre les événements hyétométriques dans le cadre d'une saison de croissance, du déficit de précipitations et de la température expliquaient 70 % de la variabilité au cours des années dans le rendement du blé Gasser et Park. Les résultats de notre analyse indiquent en outre que la production des petites céréales a été favorisée durant les saisons où les précipitations étaient plus abondantes, plus fréquentes, ou encore où la demande d'évaporation (évaporation du bac) était plus faible. Seule la production de blé semblait bénéficier de températures ambiantes minimales plus élevées. Cette étude suggère que, malgré la fraîcheur et la brièveté de la saison de croissance dans l'intérieur de l'Alaska, le facteur climatique primaire qui limite la production végétale est le stress hydrique, joint à de faibles précipitations ou à une forte demande d'évaporation. Par conséquent, les pratiques de gestion des terres qui visent à conserver l'eau du sol favoriseront très probablement la production végétale dans le Subarctique

    A Proposal for an Environmental Decision Support System at the Regional Level: Concepts, Support Methodology, Tools and their Terminology

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    One of the goals of IIASA's research activities in the area of environmental quality modeling is the integration of data and models in a unified framework to assist decision makers with the management of complex environmental systems. Building on IIASA's work undertaken within the WELMM (Water, Energy, Land, Materials and Manpower) project of the former Resources and Environment Area and the work on Decision Support Systems of the former Management and Technology Area, a conceptual framework for an environmental decision support system (EDSS) has been developed and is presented in this paper. The proposed EDSS has been developed with the interest and the financial support of the CSI, the Center for Information Systems of the Regional Government of Piemonte, Italy. The main issue addressed by this paper is to devise a system assisting decision makers in tackling environmental problems at the regional level. These decisions are typically characterized by a combination of both structured (formalizable, described in a quantitative model) and unstructured elements (incomplete information, undefined cause-effect relationships, influence of political objectives, public perception, consideration of aesthetics, etc.). The proposed EDSS enables the user to use models and data, of relevance to a particular task, which are embedded in the EDSS in the form of a process information system. The specific feature of this process information system is that it contains processes of anthropogenic nature (the socio-economic activities being the cause of environmental impacts like power plants, industrial production units, etc.) as well as natural processes determining the spatial/temporal distribution and the extent of environmental quality changes (like the dispersion and deposition of air pollutants and their effect on human population, vegetation and wildlife). The system ensures that the data and models, which have been developed in the context of specific EDSS applications are documented right from the outset and become thus equally available for further use. This becomes especially important in view of the long-term effort to be put into the development of data and models dealing with the large number of environmental problems that governments, industry and academic institutions are confronted with at the regional level

    SOFAR float trajectories from an experiment to measure the Atlantic cross equatorial flow (1989-1990)

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    Neutrally buoyant SOFAR floats at nominal depths of 800, 1800, and 3300 m were tracked for 21 months in the vicinity of western boundary currents near 6N and at several sites in the Atlantic near 11N and along the equator. Trajectories at 1800 m show a swift (>50 cm/sec), narrow (100 km wide) southward-flowing Deep Western Boundary Current (DWBC) extending from 7N to the equator. At times (February-March 1989) DWBC water turned eastward and flowed along the equator and at other times (August-September 1990) the DWBC crossed the equator and continued southward. The mean velocity near the equator was eastward from February 1989 to February 1990 and westward from March 1990 to November 1990. Thus the cross-equatorial flow in the DWBC appeared to be linked to the direction of equatorial currents which varied over periods of more than a year. No obvious DWBC nor swift equatorial current was observed by 3300 m floats. Eight-hundred-meter floats revealed a northwestward intermediate level western boundary current although flow patterns were complicated. Three floats that significantly contributed to the northwestward flow looped in anticyclonic eddies that translated up the coast at 8 cm/sec. Six 800 m floats drifted eastward along the equator between 5S and 6N at a mean velocity of 11 cm/sec; one reached 5W in the Gulf of Guinea, suggesting that the equatorial current extended at least 35-40° along the equator. Three of these floats reversed direction near the end of the tracking period, implying low frequency fluctuations.Funding was provided by the National Science Foundation through Grant Nos. OCE-8521082, OCE-8517375, and OCE-9114656

    Shearmeter floats in the area of the WHOI Brazil Basin Tracer Release Experiment : technical and oceanographic data

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    Six drifting floats designed to measure shear were deployed in the vicinity of the Brazil Basin Tracer Release Experiment. The one-year long time series of oceanographic conditions obtained by the floats are for direct comparison with long-term tracer dispersion. The purpose of the tracer dispersion experiment was to study mixing of Antarctic Bottom Water at approximately 4000 m depth with less dense water above. Two of the floats returned shear records, one from about 1660 m depth and one from about 2800 m depth. Mean shear at 1660 m was 2.2 x 10 -3 s-1 with N = 1.1 cph, about 1.9 times the Garrett-Munk model amount. Mean shear at 2800 m was 1.1 x 10-3 with N = 0.5 cph, about 2.2 times Garrett-Munk. There was no apparent depth structure to the shear recorded by the near-bottom float moving over the mountainous seafloor. The two shear time series and the local tidal velocities were not strongly correlated, but the tide and shear series did have some similarities. Some variability in the 1660-m shear may be due to atmospheric forcing. Three floats deeper than 2800 m returned one-year long trajectories. Two trajectories were persistently eastward.Funding was provided by the National Science Foundation under Grant Nos. OCE-9416014 and OCE-9906685

    Dynamics of precipitation pattern formation at geothermal hot springs

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    We formulate and model the dynamics of spatial patterns arising during the precipitation of calcium carbonate from a supersaturated shallow water flow. The model describes the formation of travertine deposits at geothermal hot springs and rimstone dams of calcite in caves. We find explicit solutions for travertine domes at low flow rates, identify the linear instabilities which generate dam and pond formation on sloped substrates, and present simulations of statistical landscape evolution

    Identification of polymorphisms and balancing selection in the male infertility candidate gene, ornithine decarboxylase antizyme 3

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    Abstract Background The antizyme family is a group of small proteins that play a role in cell growth and division by regulating the biosynthesis of polyamines (putrescine, spermidine, spermine). Antizymes regulate polyamine levels primarily through binding ornithine decarboxylase (ODC), an enzyme key to polyamine production, and targeting ODC for destruction by the 26S proteosome. Ornithine decarboxylase antizyme 3 (OAZ3) is a testis-specific antizyme paralog and the only antizyme expressed in the mid to late stages of spermatogenesis. Methods To see if mutations in the OAZ3 gene are responsible for some cases of male infertility, we sequenced and evaluated the genomic DNA of 192 infertile men, 48 men of known paternity, and 34 African aborigines from the Mbuti tribe in the Democratic Republic of the Congo. The coding sequence of OAZ3 was further screened for polymorphisms by SSCP analysis in the infertile group and an additional 250 general population controls. Identified polymorphisms in the OAZ3 gene were further subjected to a haplotype analysis using PHASE 2.02 and Arlequin 2.0 software programs. Results A total of 23 polymorphisms were identified in the promoter, exons or intronic regions of OAZ3. The majority of these fell within a region of less than two kilobases. Two of the polymorphisms, -239 A/G in the promoter and 4280 C/T, a missense polymorphism in exon 5, may show evidence of association with male infertility. Haplotype analysis identified 15 different haplotypes, which can be separated into two divergent clusters. Conclusion Mutations in the OAZ3 gene are not a common cause of male infertility. However, the presence of the two divergent haplotypes at high frequencies in all three of our subsamples (infertile, control, African) suggests that they have been maintained in the genome by balancing selection, which was supported by a test of Tajima's D statistic. Evidence for natural selection in this region implies that these haplotypes may be associated with a trait other than infertility. This trait may be related to another function of OAZ3 or a region in tight linkage disequilibrium to the gene.</p

    Digitally Enlightened or Still in the Dark? Establishing a Sector-Wide Approach to Enhancing Data Synthesis and Research Potential in British Environmental Archaeology and Beyond

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    In a 2019 Internet Archaeology article, Elizabeth Pearson posed the question 'are we back in the Dark Ages?'. This question was made in reference to a developer-funded archaeology sector that was generating vast quantities of evidence and, particularly, in recent years, specialist environmental data, but was failing to mobilise this in a theoretical framework that generated meaningful advancement in terms of research. The introduction to the 2021 Internet Archaeology special issue on Digital Archiving in Archaeology (Richards et al. 2021) went on to address 'a digital resource that is now in jeopardy' – not only because of the risk of technical obsolescence, but also because of crucial limitations to its interoperability and discoverability. This article builds on these arguments and complements vital work underway on high-level, internationally focused data infrastructure initiatives (e.g. Wright and Richards 2018). We emphasise here the importance of parallel discussions at a community level, particularly with the people who routinely produce archaeological data, as key to enhancing data synthesis and research potential. Specifically, we report on two surveys conducted by the 'Rewilding' Later Prehistory project at Oxford Archaeology, in collaboration with Historic England and Bournemouth University, which originated in the 'Rewilding' project's concern with improving access to palaeoenvironmental data produced within Britain. Substantial amounts of zooarchaeological and archaeobotanical data remain buried in grey literature, limited-access publications and archive reports (not to mention floppy disks, CDs and microfiche), with no integrative means of searching for particular periods or categories of evidence. This lack of accessibility inhibits specialists from contextualising their findings, and was exemplified recently by the Archaeology on Furlough project tripling the known number of aurochs finds in Britain by trawling online records, journals and museum records (Wiseman 2020). The results of the surveys presented here, which targeted both environmental archaeologists specifically and the wider sector, demonstrate a significant appetite amongst archaeologists to improve data networks and for their work to contribute meaningfully to research agendas. Contextualised within a disciplinary landscape that is increasingly dynamic in its approach to tackling the openness and connectivity of 'big data', we argue that better data synthesis in environmental archaeology, and the developer-funded sector more broadly, can be more than just a mirage on the horizon, particularly once the people who produce the data are given an active voice in the matter
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