504 research outputs found

    Climate Change and Water Resources in Ireland: Initial investigations using downscaled GCMS and hydrological modelling techniques.

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    Predictions are made of changes in effective runoff at a high spatial resolution for the island of Ireland under different climate change scenarios. Although previous studies have examined the response of selected Irish catchments to future climate scenarios this is the first time that the whole area of the island has been considered. This paper discusses the initial investigation that has been carried out and outlines research currently in progress. Polynomial regression techniques are used to derive a baseline climatology for Ireland. Downscaled precipitation and evaporation data from the United Kingdom Climate Program (UKCIP)for the Medium-low 2080 scenario is used together with the baseline data for the initial investigation. The precipitation and potential evaporation (PE) data are converted to a suitable form for input to HYSIM. Two sets of simulations are carried out for 825 JO x JO km grid squares covering the land area of the island of Ireland for the baseline period and the 2080 scenario. The hydrological parameters for each of these squares are considered to be identical for this initial investigation. The results of this investigation are presented. Future work is considered, focusing on the parameterisation of HYSIM for individual grid cells. The initial investigation demonstrates that the representation of storage is of particular importance. Parameter values are derived for each square using data from the Soil Survey of Ireland, the CORINE land use database and information on major aquifers provided by the Geological Survey of Ireland. The flexible data requirements of HYSIM allow some representation of the diverse hydrological conditions found within Ireland. For example, approximately 40% of Ireland is underlain by limestones, many of which are karstified. These karst aquifers are an important water resource and can respond very rapidly to precipitation inputs. There are also extensive areas of lakes and wetlands. The land area is divided into broad hydrological zones to provide some representation of this variability

    A theoretical explanation for the Central Molecular Zone asymmetry

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    It has been known for more than thirty years that the distribution of molecular gas in the innermost 300 parsecs of the Milky Way, the Central Molecular Zone, is strongly asymmetric. Indeed, approximately three quarters of molecular emission comes from positive longitudes, and only one quarter from negative longitudes. However, despite much theoretical effort, the origin of this asymmetry has remained a mystery. Here we show that the asymmetry can be neatly explained by unsteady flow of gas in a barred potential. We use high-resolution 3D hydrodynamical simulations coupled to a state-of-the-art chemical network. Despite the initial conditions and the bar potential being point-symmetric with respect to the Galactic Centre, asymmetries develop spontaneously due to the combination of a hydrodynamical instability known as the "wiggle instability" and the thermal instability. The observed asymmetry must be transient: observations made tens of megayears in the past or in the future would often show an asymmetry in the opposite sense. Fluctuations of amplitude comparable to the observed asymmetry occur for a large fraction of the time in our simulations, and suggest that the present is not an exceptional moment in the life of our Galaxy.Comment: Accepted for publication in MNRAS. Videos of the simulations are available at http://www.ita.uni-heidelberg.de/~mattia/download.htm

    HST ultraviolet spectral energy distributions for three ultraluminous infrared galaxies

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    We present HST Faint Object Camera ultraviolet (230 nm and 140 nm) images of three ultraluminous infrared galaxies (ULIG: L_ir > 10^12 L_sun) selected from the IRAS Revised Bright Galaxy Sample. The purpose is to estimate spectral energy distributions (SEDs) to facilitate the identification of similar objects at high redshift in deep optical, infrared, and submm surveys. All three galaxies (VII Zw031 = IRAS F12112+0305, and IRAS F22491-1808) were well detected at 230 nm. Two of the three were marginally detected at 140 nm. The fluxes, together with ground-based optical and infrared photometry, are used to compute SEDs over a wide wavelength range. The measured SEDs drop from the optical to the ultraviolet, but the magnitude of the drop ranges from a factor of ~3 in IRAS F22491-1808 to a factor of ~100 in VIIZw031. This is most likely due to different internal extinctions. Such an interpretation is also suggested by extrapolating to ultraviolet wavelengths the optical internal extinction measured in VIIZw031. K-corrections are calculated to determine the colors of the sample galaxies as seen at high redshifts. Galaxies like VIIZw031 have very low observed rest-frame UV fluxes which means that such galaxies at high redshift will be extremely red or even missing in optical surveys. On the other hand, galaxies like IRAS F12112+0305 and IRAS F22491-1808, if seen at high redshift, would be sufficiently blue that they would not easily be distinguished from normal field galaxies, and therefore, identified as ULIGs. The implication is then that submillimeter surveys may be the only means of properly identifying the majority of ULIGs at high redshift.Comment: AJ in press, TeX, 23 pages, 7 tab, 17 figs available also (at higher resolution) from http://www.ast.cam.ac.uk~trentham/ufigs.htm

    Evaluating the spatial transferability and temporal repeatability of remote sensing-based lake water quality retrieval algorithms at the European scale:a meta-analysis approach

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    Many studies have shown the considerable potential for the application of remote-sensing-based methods for deriving estimates of lake water quality. However, the reliable application of these methods across time and space is complicated by the diversity of lake types, sensor configuration, and the multitude of different algorithms proposed. This study tested one operational and 46 empirical algorithms sourced from the peer-reviewed literature that have individually shown potential for estimating lake water quality properties in the form of chlorophyll-a (algal biomass) and Secchi disc depth (SDD) (water transparency) in independent studies. Nearly half (19) of the algorithms were unsuitable for use with the remote-sensing data available for this study. The remaining 28 were assessed using the Terra/Aqua satellite archive to identify the best performing algorithms in terms of accuracy and transferability within the period 2001–2004 in four test lakes, namely Vänern, Vättern, Geneva, and Balaton. These lakes represent the broad continuum of large European lake types, varying in terms of eco-region (latitude/longitude and altitude), morphology, mixing regime, and trophic status. All algorithms were tested for each lake separately and combined to assess the degree of their applicability in ecologically different sites. None of the algorithms assessed in this study exhibited promise when all four lakes were combined into a single data set and most algorithms performed poorly even for specific lake types. A chlorophyll-a retrieval algorithm originally developed for eutrophic lakes showed the most promising results (R2 = 0.59) in oligotrophic lakes. Two SDD retrieval algorithms, one originally developed for turbid lakes and the other for lakes with various characteristics, exhibited promising results in relatively less turbid lakes (R2 = 0.62 and 0.76, respectively). The results presented here highlight the complexity associated with remotely sensed lake water quality estimates and the high degree of uncertainty due to various limitations, including the lake water optical properties and the choice of methods

    Proteinase-activated receptor 2 modulates OA-related pain, cartilage and bone pathology

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    Objective Proteinase-activated receptor 2 (PAR2) deficiency protects against cartilage degradation in experimental osteoarthritis (OA). The wider impact of this pathway upon OA-associated pathologies such as osteophyte formation and pain is unknown. Herein, we investigated early temporal bone and cartilage changes in experimental OA in order to further elucidate the role of PAR2 in OA pathogenesis. Methods OA was induced in wild-type (WT) and PAR2-deficient (PAR2−/−) mice by destabilisation of the medial meniscus (DMM). Inflammation, cartilage degradation and bone changes were monitored using histology and microCT. In gene rescue experiments, PAR2−/− mice were intra-articularly injected with human PAR2 (hPAR2)-expressing adenovirus. Dynamic weight bearing was used as a surrogate of OA-related pain. Results Osteophytes formed within 7 days post-DMM in WT mice but osteosclerosis was only evident from 14 days post induction. Importantly, PAR2 was expressed in the proliferative/hypertrophic chondrocytes present within osteophytes. In PAR2−/− mice, osteophytes developed significantly less frequently but, when present, were smaller and of greater density; no osteosclerosis was observed in these mice up to day 28. The pattern of weight bearing was altered in PAR2−/− mice, suggesting reduced pain perception. The expression of hPAR2 in PAR2−/− mice recapitulated osteophyte formation and cartilage damage similar to that observed in WT mice. However, osteosclerosis was absent, consistent with lack of hPAR2 expression in subchondral bone. Conclusions This study clearly demonstrates PAR2 plays a critical role, via chondrocytes, in osteophyte development and subchondral bone changes, which occur prior to PAR2-mediated cartilage damage. The latter likely occurs independently of OA-related bone changes

    Project Vestia: Future of Martian Habitats

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    Project Vestia’s main goal is to design and test a floor for inflatable habitat modules (IHM) in Martian or Lunar environments. Currently, there is no method for creating a stable floor in an IHM that does not inhibit the benefits of using that module, as there is for a hard shell habitat. The scope of this project is to: design and simulate three designs; manufacture and test scale models of the top two performing models; design, manufacture, and test different hinge constructions. Each final scale model must withstand 1668.2 N of downwardly applied force, a scaled down representation of what could be typical use modified to account for difference in gravitational pull. Three folding designs were created with Fusion 360 computer modeling software, and simulation was performed using ANSYS software. The hinges used in each model are all of one design but multiple different construction methods. Hinges were manufactured using each method, and then were subsequently tested to determine each method’s tensile strength and flexibility. The parts are all manufactured and tested by the student researchers in house, with materials obtained externally. Preliminary results show that with current design methodology, all models have a minimum factor of safety of 1.5 at the weakest point, compared to at least 5 across the rest of each design. The end goal of this project is to confirm a design and create a scale model of the best design with the best hinge construction method and publish the findings to encourage further research and apply this technology in future IHMs

    Identifying robust response options to manage environmental change using an ecosystem approach:a stress-testing case study for the UK

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    A diverse range of response options was evaluated in terms of their utility for sustaining ecosystem services in the UK. Robustness of response options was investigated by applying a ‘stress-testing’ method which evaluated expected performance against combined scenarios of socioeconomic and climate change. Based upon stakeholder feedback, a reference scenario representing current trends in climate and socioeconomic drivers (‘business-as-usual’) was used as a dynamic baseline against which to compare results of other scenarios. The robustness of response options was evaluated by their utility in different environmental and social contexts as represented by the scenarios, and linked to their adaptability to adjust to changing conditions. Key findings demonstrate that adaptability becomes increasingly valuable as the magnitude and rate of future change diverges from current trends. Stress-testing also revealed that individual responses in isolation are unlikely to be robust meaning there are advantages from integrating cohesive combinations (bundles) of response options to maximise their individual strengths and compensate for weaknesses. This identifies a role for both top-down and bottom-up responses, including regulation, spatial targeting, incentives and partnership initiatives, and their use in combination through integrated assessment and planning consistent with the adoption of an Ecosystem Approach. Stress-testing approaches can have an important role in future-proofing policy appraisals but important knowledge gaps remain, especially for cultural and supporting ecosystem services. Finally, barriers and enablers to the implementation of more integrated long-term adaptive responses were identified drawing on the ‘4 Is’ (Institutions, Information, Incentives, Identity) conceptual framework. This highlighted the crucial but usually understated role of identity in promoting ownership and uptake of responses

    Trophic rewilding presents regionally specific opportunities for mitigating climate change

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    Large-bodied mammalian herbivores can influence processes that exacerbate or mitigate climate change. Herbivore impacts are, in turn, influenced by predators that place top-down forcing on prey species within a given body size range. Here, we explore how the functional composition of terrestrial large herbivore and carnivore guilds vary between three mammal distribution scenarios: Present-Natural, Current-Day, and Extant-Native Trophic (ENT) Rewilding. Considering the effects of herbivore species weakly influenced by top-down forcing, we quantify the relative influence keystone large herbivore guilds have on methane emissions, woody vegetation expansion, fire dynamics, large-seed dispersal, and nitrogen and phosphorous transport potential. We find strong regional differences in the number of herbivores under weak top-down regulation between our three scenarios with important implications for how they will influence climate change relevant processes. Under the Present-Natural non-ruminant, megaherbivore, browsers were a particularly important guild across much of the world. Megaherbivore extinction and range contraction and the arrival of livestock means large, ruminant, grazers have become more dominant. ENT Rewilding can restore the Afrotropics and Indo-Malay to the Present-Natural benchmark, but causes top-down forcing of the largest herbivores to become common place elsewhere. ENT Rewilding will reduce methane emissions, but does not maximise Natural Climate Solution potential

    Individual patient data meta-analysis of organ failure in acute pancreatitis : protocol of the PANCREA II study

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    Context Organ failure is a major determinant of mortality in patients with acute pancreatitis. These patients usually requireadmission to high dependency or intensive care units and consume considerable health care resources. Given a low incidence rate of organ failure and a lack of large non-interventional studies in the field of acute pancreatitis, the characteristics of organ failure that influence outcomes of patients with acute pancreatitis remain largely unknown. Therefore, the Pancreatitis Across Nations Clinical Research and Education Alliance (PANCREA) aims to conduct a meta-analysis of individual patient data from prospective non-interventional studies to determine the influence of timing, duration, sequence, and combination of different organ failures on mortality in patients with acute pancreatitis. Methods Pancreatologists currently active with acute pancreatitis clinical research will be invited to contribute. To be eligible for inclusion patients will have to meet the criteria of acute pancreatitis, develop at least one organ failure during the first week of hospitalization, and not be enrolled into an intervention study. Raw data will then be collated and checked. Individual patient data analysis based on a logistic regression model with adjustment for confounding variables will be done. For all analyses, corresponding 95% confidence intervals and P values will be reported. Conclusion This collaborative individual patient data meta-analysis will answer important clinical questions regarding patients with acute pancreatitis that develop organ failure. Information derived from this study will be used to optimize routine clinical management and improve care strategies. It can also help validate outcome definitions, allow comparability of results and form a more accurate basis for patient allocation in further clinical studies

    Dexamethasone impairs the expression of antimicrobial mediators in lipopolysaccharide-activated primary macrophages by inhibiting both expression and function of interferon β

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    Glucocorticoids potently inhibit expression of many inflammatory mediators, and have been widely used to treat both acute and chronic inflammatory diseases for more than seventy years. However, they can have several unwanted effects, amongst which immunosuppression is one of the most common. Here we used microarrays and proteomic approaches to characterise the effect of dexamethasone (a synthetic glucocorticoid) on the responses of primary mouse macrophages to a potent pro-inflammatory agonist, lipopolysaccharide (LPS). Gene ontology analysis revealed that dexamethasone strongly impaired the lipopolysaccharide-induced antimicrobial response, which is thought to be driven by an autocrine feedback loop involving the type I interferon IFNβ. Indeed, dexamethasone strongly and dose-dependently inhibited the expression of IFNβ by LPS-activated macrophages. Unbiased proteomic data also revealed an inhibitory effect of dexamethasone on the IFNβ-dependent program of gene expression, with strong down-regulation of several interferon-induced antimicrobial factors. Surprisingly, dexamethasone also inhibited the expression of several antimicrobial genes in response to direct stimulation of macrophages with IFNβ. We tested a number of hypotheses based on previous publications, but found that no single mechanism could account for more than a small fraction of the broad suppressive impact of dexamethasone on macrophage type I interferon signaling, underlining the complexity of this pathway. Preliminary experiments indicated that dexamethasone exerted similar inhibitory effects on primary human monocyte-derived or alveolar macrophages.</p
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