34 research outputs found
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Global forecasting of thermal health hazards: the skill of probabilistic predictions of the Universal Thermal Climate Index (UTCI)
Although over a hundred thermal indices can be used for assessing thermal health hazards, many ignore the human heat budget, physiology and clothing. The Universal Thermal Climate Index (UTCI) addresses these shortcomings by using an advanced thermo-physiological model. This paper assesses the potential of using the UTCI for forecasting thermal health hazards. Traditionally, such hazard forecasting has had two further limitations: it has been narrowly focused on a particular region or nation and has relied on the use of single ‘deterministic’ forecasts. Here, the UTCI is computed on a global scale,which is essential for international health-hazard warnings and disaster preparedness, and it is provided as a probabilistic forecast. It is shown that probabilistic UTCI forecasts are superior in skill to deterministic forecasts and that despite global variations, the UTCI forecast is skilful for lead times up to 10 days. The paper also demonstrates the utility of probabilistic UTCI forecasts on the example of the 2010 heat wave in Russia
Magnesia-Based Cements: A Journey of 150 Years, and Cements for the Future?
This review examines the detailed chemical insights that have been generated through 150 years of work worldwide on magnesium-based inorganic cements, with a focus on both scientific and patent literature. Magnesium carbonate, phosphate, silicate-hydrate, and oxysalt (both chloride and sulfate) cements are all assessed. Many such cements are ideally suited to specialist applications in precast construction, road repair, and other fields including nuclear waste immobilization. The majority of MgO-based cements are more costly to produce than Portland cement because of the relatively high cost of reactive sources of MgO and do not have a sufficiently high internal pH to passivate mild steel reinforcing bars. This precludes MgO-based cements from providing a large-scale replacement for Portland cement in the production of steel-reinforced concretes for civil engineering applications, despite the potential for CO2 emissions reductions offered by some such systems. Nonetheless, in uses that do not require steel reinforcement, and in locations where the MgO can be sourced at a competitive price, a detailed understanding of these systems enables their specification, design, and selection as advanced engineering materials with a strongly defined chemical basis
Pump-probe X-ray holographic imaging of laser-induced cavitation bubbles with femtosecond FEL pulses
Cavitation bubbles show many nonlinear characteristics of liquid and gas phase. Here the authors demonstrate coherent diffractive imaging of cavitation bubble using infrared pump and XFEL probe and discuss the formation and evolution of the bubbles
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AGN Host Galaxies At Redshift Z Approximate To 0.7: Peculiar Or Not?
Aims. We perform a quantitative morphological comparison between the hosts of active galactic nuclei (AGN) and quiescent galaxies at intermediate redshifts (z approximate to 0.7). The imaging data are taken from the large HST/ACS mosaics of the GEMS and STAGES surveys. Our main aim is to test whether nuclear activity at this cosmic epoch is triggered by major mergers. Methods. Using images of quiescent galaxies and stars, we created synthetic AGN images to investigate the impact of an optical nucleus on the morphological analysis of AGN hosts. Galaxy morphologies are parameterized using the asymmetry index A, the concentration index C, the Gini coefficient G, and the M-20 index. A sample of similar to 200 synthetic AGN was matched to 21 real AGN in terms of redshift, host brightness, and host-to-nucleus ratio to ensure a reliable comparison between active and quiescent galaxies. Results. The optical nuclei strongly affect the morphological parameters of the underlying host galaxy. Taking these effects into account, we find that the morphologies of the AGN hosts are clearly distinct from galaxies undergoing violent gravitational interactions. Indeed, the host galaxy distributions in morphological descriptor space are more similar to undisturbed galaxies than to major mergers. Conclusions. Intermediate-luminosity (L-X less than or similar to 10(44) erg/s) AGN hosts at z approximate to 0.7 show morphologies similar to the general population of massive galaxies with significant bulges at the same redshifts. If major mergers are the driver of nuclear activity at this epoch, the signatures of gravitational interactions fade rapidly before the optical AGN phase starts, making them undetectable on single-orbit HST images, at least with usual morphological descriptors. This could be investigated in future synthetic observations created from numerical simulations of galaxy-galaxy interactions.Deutsches Zentrum fur Luft- und Raumfahrt 50 OR 0404Austrian Science Foundation FWF P19300-N16, P23946-N16FWF P18416STFCEuropean Commission MOIF-CT-2006-21891CITAScience and Technology Facilities Council (STFC)Deutsche ForschungsgemeinschaftNASA under LTSA NAG5-13063,
NAG5-13102NSF AST-0607748HST from STScI GO-11082STScINRC-HIASpanish MEC AYA2005-09413-C02-02NASA through STScI GO-10395, NAS5-26555Astronom