82 research outputs found
Interannual Variability in Carbon Dioxide Flux from a High Arctic Fen Estimated by Measurements and Modeling
No full textThe response of high arctic ecosystems' carbon dioxide exchange to changing climate is uncertain and may be important from a climate-change perspective. In this study, the net ecosystem carbon dioxide exchange during four growing seasons is examined by combining measurements and modeling from a high arctic fen in northeastern Greenland. The summer-season net ecosystem exchange shows large interannual variations, fluctuating from an uptake of −50 g C m−2 to −123 g C m−2. Through ecosystem modeling, we can observe that leaf area index development and the maximum Rubisco capacity are more important controls on the interannual variability of net ecosystem carbon dioxide exchange than meteorological conditions. Furthermore, we present a hypothesis linking the interannual variability in maximum Rubisco capacity with leaf nitrogen content and leaf area index development. This hypothesis may provide a method to model seasonal net ecosystem carbon dioxide exchange in detail without having to resort to elaborate fitting procedures using measured carbon dioxide flux data.This article was published in Arctic, Antarctic, and Alpine Research (2005), and this Version of Record is archived in RUcore with permission. The published article is available from the Institute of Arctic and Alpine Research (INSTAAR) at: http://instaar.colorado.edu/aaar/journal_issues/abstract.php?id=2353Peer reviewe
Nurturing creativity: A journey of personal transformation
No full textThe ‘idea’ of creativity invariably seems to meet with general approval. In fact, together with ‘innovation’, ‘creativity’ has become a common catchcry of our times. After all, we are told that we are living in the “Creative Age”, and we constantly look to innovation as being the answer to the problems that we perceive to be facing. However, it is one thing to like an ‘idea’, and quite another to be willing to make the journey to discover some of its possible sources - this is the difference between thinking and doing, the difference between theory and reality. Theory could be described as thinking that has been formalised and reality as the whole where living unfolds; so while there can already be considerable difference between thinking and doing, there is a ‘chasm’ between theory and reality.
This thesis is a representation in words of an actual occurrence – a personal transformation, a change in attitude. This could be described in more detail as a conscious opening to perceiving with an attitude of creativity by attending to the nurturing of creativity. A personal journey is unique, yet a human life is as much about relationships and connections as it is about personal growth. I have therefore chosen the company of guides to help me travel this journey. The main three are: Carl Jung for his support on exploring the whole of the ‘self’; David Bohm for his lucidity in expressing a holistic view of reality; and Robert Nash for his encouragement, through the use of scholarly personal narrative, on including lived experience in academic writing. Besides them, many others have been consulted on creativity and the nurturing of creativity, including some through interviews. By delving into creativity, both within and outside the territory of the ‘self’, this thesis also explores how perception is affected by societal concerns, with one of the principal influences discussed being the hierarchical order we live by – patriarchy.
It was my search for creativity that made me realise the need of nurturing my creativity in order to find it. This in turn led me to seek wholeness; thereby it was inherent that I should link the personal with the social and the academic. Thus in the writing of this thesis I have found myself weaving webs of connections, often across sheer windy chasms of dissent, to bridge academic writing with lived experience and the nurturing of creativity, through as holistic a perspective as I could access at the time of writing. The beauty of webs is that they hold, having innumerable points of connection to support them. Even if they are broken they can be built again and be made stronger, with ever expanding clusters of creative interconnections, as in our diverse human community new ways of seeing are constantly emerging and growing through the nurturing of creativity
An underestimated role of precipitation frequency in regulating summer soil moisture
No full textSoil moisture induced droughts are expected to become more frequent under future global climate change. Precipitation has been previously assumed to be mainly responsible for variability in summer soil moisture. However, little is known about the impacts of precipitation frequency on summer soil moisture, either interannually or spatially. To better understand the temporal and spatial drivers of summer drought, 415 site yr measurements observed at 75 flux sites world wide were used to analyze the temporal and spatial relationships between summer soil water content (SWC) and the precipitation frequencies at various temporal scales, i.e., from half-hourly, 3, 6, 12 and 24 h measurements. Summer precipitation was found to be an indicator of interannual SWC variability with r of 0.49 (p < 0.001) for the overall dataset. However, interannual variability in summer SWC was also significantly correlated with the five precipitation frequencies and the sub-daily precipitation frequencies seemed to explain the interannual SWC variability better than the total of precipitation. Spatially, all these precipitation frequencies were better indicators of summer SWC than precipitation totals, but these better performances were only observed in non-forest ecosystems. Our results demonstrate that precipitation frequency may play an important role in regulating both interannual and spatial variations of summer SWC, which has probably been overlooked or underestimated. However, the spatial interpretation should carefully consider other factors, such as the plant functional types and soil characteristics of diverse ecoregions
Detrital zircon geochronology of the Grenville/Llano foreland and basal Sauk Sequence in west Texas, USA
No full textWe thank the University of St. Andrews and Natural Environment Research Council (NERC grant NE/J021822/1) for funding support. The NERC Isotope Geosciences Facilities Steering Committee (IP-1326-0512) provided additional funding support.U-Pb detrital zircon ages from Mesoprotero zoic and Cambrian siliciclastic units in west Texas (USA) constrain the depositional setting, provenance, and tectonic history of the region within a late Mesoproterozoic Grenville foreland basin and the early Paleozoic Sauk transgressive sequence. Two key units, the Hazel and Lanoria Formations, have detrital zircon age spectra dominated by detritus derived from the Grenville orogen (the Llano uplift and eroded equivalents), the ca. 1.4 Ga Granite Rhyolite, and the ca. 1.7-1.6 Ga Yavapai/ Mazatzal provinces. These data, combined with sedimentological data, permit interpreting those formations as the proximal and distal deposits, respectively, of a molasse shed into the Grenvillian foreland basin. Detrital zircons as young as ca. 520 Ma show that the Van Horn Formation, previously considered to be Precambrian in age, is no older than middle Cambrian. Further, the overall detrital zircon age spectrum of the Van Horn Formation is similar to that of the overlying Cambro-Ordovician Bliss Formation: both indicate derivation from sources that included the Colorado- Oklahoma aulacogen, Grenville, Granite- Rhyolite, and Yavapai/Mazatzal provinces. The similarities between the depositional history of the Van Horn and Bliss Formations lead us to conclude that the base of the Sauk Sequence in west Texas occurs at the base of the Van Horn Formation. Base-level rise associated with the Sauk transgression affected drainage patterns and sediment deposition along southwestern Laurentia some 20 m.y. earlier than previously assumed.Peer reviewe
Long-term impact of baseline anaemia on clinical outcomes following percutaneous coronary intervention in stable angina
No full textBACKGROUND: In patients with stable angina (SA), the clinical benefits of percutaneous coronary intervention (PCI) reside almost exclusively within the realm of symptomatic improvement rather than improvement in hard clinical endpoints. The benefits of PCI should always be balanced against its potential short-term and long-term risks. Common among these risks is the presence of anaemia and its interaction with poor clinical outcomes and increased morbidity; this study aims to elucidate the impact of anaemia on long-term clinical outcomes of this patient group.METHODS: From Danish national registries, we identified patients with SA treated with PCI who had a haemoglobin measurement maximum of 90 days prior to PCI procedure. Anaemia was defined as haemoglobin <130 and <120 g/L in men and women, respectively. Follow-up was up to 3 years after PCI, and Cox regression was used to estimate HRs with 95% CIs of hospitalisation due to bleeding, acute coronary syndrome (ACS) and all-cause mortality in patients with anaemia compared with patients without anaemia.RESULTS: Of 2837 included patients, 14.6% had anaemia prior to PCI. During follow-up, 93 patients (3.3%) had a bleeding episode, which was higher in patients with anaemia (5.8%) compared with patients without anaemia (2.8%). A total of 213 patients (7.5%) developed ACS, which was higher in patients with anaemia (10.6%) compared with patients without anaemia (7.0%). Furthermore, 185 patients (6.5%) died, with a mortality rate of 18.1% in patients with anaemia compared with 4.5% in patients without anaemia. In multivariable analyses, anaemia was associated with a significantly increased risk of bleeding (HR 1.69; 95% CI 1.04 to 2.73; P 0.033), ACS (HR 1.47; 95% CI 1.04 to 2.10; P 0.031) and all-cause mortality (HR 2.41; 95% CI 1.73 to 3.30; P <0.001).CONCLUSION: Anaemia in patients with SA was significantly associated with bleeding, ACS and all-cause mortality following PCI.</p
Return to work and maintenance of work after first time hospitalization for atrial fibrillation or flutter
No full textRecalculating Default Values for Palm Oil
No full textOn 05 December 2010, the Renewable Energy Directive (RED) came into force in the EU. Member States are still working to fully transpose the Directive into national law and establish a framework for achieving their legally binding greenhouse gas (GHG) emission reductions. However, governments got off to a slow start as debate continues on the validity of the directives foundations including the default values used to measure the sustainability of biofuels. Only sustainable biofuels can be counted towards Member State targets. This, as a matter of principle, makes sense with respect to the very aim of renewable energy policies. On the other hand, the vague and distortive formulation and values regarding what is to be classified as "sustainable" have negatively impacted the perception of the underlying scientific base and methodologies as well as the reliability in the European biofuels sector. This uncertainty and the ongoing controversial debates are affecting investment and progress in the biofuel sector not just in Europe but all over the world. Producers of soybeans in the US, sugarcane in Brazil and palm oil in Malaysia and Indonesia as well as European importers and end-users of these products have all been sharply critical of the default values, citing significant variations in calculations that undermine the credibility of the values contained in the Directive. Given the remarkable difference between the calculation of carbon reduction performance of palm oil based biofuel by the EU and a range of scientific studies which we documented in an earlier paper (Pehnelt and Vietze 2009), we are re-calculating GHG emissions saving potentials for palm oil biodiesel in order to further assess the carbon footprint of palm oil to overcome the lack of transparency in existing publications on the issue and EU regulations governing the biofuel feed-stocks. The aim of this paper is to calculate realistic and transparent scenario based CO2-emission values for the GHG emission savings of palm oil fuel compared with fossil fuel. Using the calculation scheme proposed by the Renewable Energy Directive (RED), we derive a more realistic overall default value for palm oil diesel by using current input and output data of biofuel production (e.g. in South-East Asia) and documenting every single step in detail. We calculate different scenarios in which reliable data on the production conditions (and the regarding emission values during the production chain) of palm oil diesel are used. Our conservative calculations based on the Joint Research Centre's (JEC 2011) background data and current publications on palm oil production result in GHG emissions saving potentials of palm oil based biodiesel fairly above the 35% threshold. We cannot reproduce the EU's GHG saving values for palm oil. Rather, our results confirm the higher values obtained by other studies mentioned in our last paper (Pehnelt and Vietze 2009) and elsewhere in this study. Our results indicate default values for the GHG emission savings potential of palm oil biodiesel not only way beyond the 19 percent default value published in RED but also beyond the 35 percent threshold. Our findings conclude that the more accurate default value for palm oil feedstock for electricity generation to be 52%, and for transportation biodiesel between 38.5% and 41%, depending on the fossil fuel comparator. Our results confirm the findings by other studies and challenge the official default values published in RED. As indicated by lawsuits filed by environmental NGOs against the Commission for greater transparency related to the assessment of biofuels, the process has been severely lacking in full disclosure of metrics used to achieve the values contained in the Renewable Energy Directive. As a result, the reliability of the Directive to support the EU's low-carbon ambitions is being undermined, exposing the EU and Commission to charges of trade discrimination and limiting the ability of Member States to achieve their legally binding GHG emission reductions. This analysis demonstrates that a full review of the values contained in the Directive should be undertaken and the values revised to ensure their accuracy, and raises questions as to the method that the values were originally established. Were outside parties consulted, including the industries directly affected by the assessments in the Directive? Were these values peer reviewed? In light of grievances expressed by producers throughout the world, including US soybean growers, Brazilian sugarcane farmers, and Malaysian and Indonesian palm growers, ensuring the Directive does not discriminate against imports is critical to the long-term efforts in the EU to reduce GHG emissions.Biofuel, Palm Oil, Biodiesel, RED, Renewable Energy Directive, Default Values, GHG-emissions
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