691 research outputs found

    Towards revised physically based parameter estimation methods for the Pitman monthly rainfall-runoff model

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    This paper presents a preliminary stage in the development of an alternative parameterisation procedure for the Pitman monthly rainfall runoff model which enjoys popular use in water resource assessment in Southern Africa. The estimation procedures are based on the premise that it is possible to use physical basin properties directly in the quantification of the soil moisture accounting, runoff, and recharge and infiltration parameters. The results for selected basins show that the revised parameters are at least as good as current regionalised sets or give satisfactory results in areas where no regionalised parameters exist

    Bath's law Derived from the Gutenberg-Richter law and from Aftershock Properties

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    The empirical Bath's law states that the average difference in magnitude between a mainshock and its largest aftershock is 1.2, regardless of the mainshock magnitude. Following Vere-Jones [1969] and Console et al. [2003], we show that the origin of Bath's law is to be found in the selection procedure used to define mainshocks and aftershocks rather than in any difference in the mechanisms controlling the magnitude of the mainshock and of the aftershocks. We use the ETAS model of seismicity, which provides a more realistic model of aftershocks, based on (i) a universal Gutenberg-Richter (GR) law for all earthquakes, and on (ii) the increase of the number of aftershocks with the mainshock magnitude. Using numerical simulations of the ETAS model, we show that this model is in good agreement with Bath's law in a certain range of the model parameters.Comment: major revisions, in press in Geophys. Res. Let

    ‘Sons of athelings given to the earth’: Infant Mortality within Anglo-Saxon Mortuary Geography

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    FOR 20 OR MORE YEARS early Anglo-Saxon archaeologists have believed children are underrepresented in the cemetery evidence. They conclude that excavation misses small bones, that previous attitudes to reporting overlook the very young, or that infants and children were buried elsewhere. This is all well and good, but we must be careful of oversimplifying compound social and cultural responses to childhood and infant mortality. Previous approaches have offered methodological quandaries in the face of this under-representation. However, proportionally more infants were placed in large cemeteries and sometimes in specific zones. This trend is statistically significant and is therefore unlikely to result entirely from preservation or excavation problems. Early medieval cemeteries were part of regional mortuary geographies and provided places to stage events that promoted social cohesion across kinship systems extending over tribal territories. This paper argues that patterns in early Anglo-Saxon infant burial were the result of female mobility. Many women probably travelled locally to marry in a union which reinforced existing social networks. For an expectant mother, however, the safest place to give birth was with experience women in her maternal home. Infant identities were affected by personal and legal association with their mother’s parental kindred, so when an infant died in childbirth or months and years later, it was their mother’s identity which dictated burial location. As a result, cemeteries central to tribal identities became places to bury the sons and daughters of a regional tribal aristocracy

    MASS TIMBER CONSTRUCTION IN AUSTRALIA AND NEW ZEALAND—STATUS, AND ECONOMIC AND ENVIRONMENTAL INFLUENCES ON ADOPTION

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    Mass timber construction in Australia and New Zealand uses three main materials—laminated veneer lumber, glue laminated timber and cross-laminated timber (CLT). This article focuses on the use of mass timber in nonresidential construction—the use in single-family homes and apartments is not considered. In Australia and New Zealand, mass timber building technology has moved from being technologically possible to being a feasible alternative to reinforced concrete and steel construction. It has not taken over a large market share in either market and, as such, has not been a disruptive technology. The major changes in this market in the past 5-10 yr in Australia and New Zealand have been the development of new industrial capacity in CLT and the acquisition of computer controlled machining equipment to facilitate prefabrication of wooden building components. The development of new codes and standards and design guides is underway. The drivers of future growth in market share are expected to include more clients putting a higher weight on the various environmental benefits of building in wood, reduction in the real and perceived professional risk for builders and architects specifying mass timber construction, and fuller participation in the supply chain for timber buildings (from design to construction) by timber building specialists. Government policies to encourage the use of timber may also be helpful. Engineers and architects will continue to learn—through experience—how to optimize building construction methods to take advantage of the specific features and qualities of timber as a construction method. 

    Mental health in hospital emergency departments: cross-sectional analysis of attendances in England 2013/2014

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    Objective: To describe the population of patients who attend emergency departments (ED) in England for mental health reasons. / Methods: Cross-sectional observational study of 6 262 602 ED attendances at NHS (National Health Service) hospitals in England between 1 April 2013 and 31 March 2014. We assessed the proportion of attendances due to psychiatric conditions. We compared patient sociodemographic and attendance characteristics for mental health and non-mental health attendances using logistic regression. / Results: 4.2% of ED attendances were attributable to mental health conditions (median 3.2%, IQR 2.6% to 4.1%). Those attending for mental health reasons were typically younger (76.3% were aged less than 50 years), of White British ethnicity (73.2% White British), and resident in more deprived areas (59.9% from the two most deprived Index of Multiple Deprivation quintiles (4 and 5)). Mental health attendances were more likely to occur ‘out of hours’ (68.0%) and at the weekend (31.3%). Almost two-thirds were brought in by ambulance. A third required admission, but around a half were discharged home. / Conclusions: This is the first national study of mental health attendances at EDs in England. We provide information for those planning and providing care, to ensure that clinical resources meet the needs of this patient group, who comprise 4.2% of attendances. In particular, we highlight the need to strengthen the availability of hospital and community care ‘out of hours.

    Modelling of the effect of ELMs on fuel retention at the bulk W divertor of JET

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    Effect of ELMs on fuel retention at the bulk W target of JET ITER-Like Wall was studied with multi-scale calculations. Plasma input parameters were taken from ELMy H-mode plasma experiment. The energetic intra-ELM fuel particles get implanted and create near-surface defects up to depths of few tens of nm, which act as the main fuel trapping sites during ELMs. Clustering of implantation-induced vacancies were found to take place. The incoming flux of inter-ELM plasma particles increases the different filling levels of trapped fuel in defects. The temperature increase of the W target during the pulse increases the fuel detrapping rate. The inter-ELM fuel particle flux refills the partially emptied trapping sites and fills new sites. This leads to a competing effect on the retention and release rates of the implanted particles. At high temperatures the main retention appeared in larger vacancy clusters due to increased clustering rate

    Unsafe building: documenting heritage at risk through robotic and semi-autonomous survey

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    The National Trust cares for many places where access to heritage is restricted, for safety or other reasons, limiting the opportunity for monitoring, recording and visitor engagement. The remains of the Atomic Weapons Research Establishment (AWRE) testing facility, built between 1954 and 1962 at Orford Ness on the Suffolk coast of England, represent such a case. The AWRE structures are a Scheduled Monument and sit within a wider landscape of twentieth century defence heritage. The buildings have attained a mythical status in popular culture and attract substantial visitor interest. However, they are unsafe to enter, and their long-term conservation strategy is to allow their gradual decline to a point where significant evidence is lost, with their ultimate loss to coastal erosion anticipated. Recognising these challenges, our work has sought to develop and assess a prototype use of robotic and semi-autonomous survey technology for heritage at risk in challenging environments. A suite of complementary technologies, including Boston Dynamics quadruped robots, caged and conventional drones combining laser scanning and digital photogrammetry were used. This paper provides an account of practicalities, benefits and limitations of robotic and semi-autonomous survey for documenting heritage assets
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