Ensemble prediction for nowcasting with a convection-permitting model - II: forecast error statistics

A 24-member ensemble of 1-h high-resolution forecasts over the Southern United Kingdom is used to study short-range forecast error statistics. The initial conditions are found from perturbations from an ensemble transform Kalman filter. Forecasts from this system are assumed to lie within the bounds of forecast error of an operational forecast system. Although noisy, this system is capable of producing physically reasonable statistics which are analysed and compared to statistics implied from a variational assimilation system. The variances for temperature errors for instance show structures that reflect convective activity. Some variables, notably potential temperature and specific humidity perturbations, have autocorrelation functions that deviate from 3-D isotropy at the convective-scale (horizontal scales less than 10 km). Other variables, notably the velocity potential for horizontal divergence perturbations, maintain 3-D isotropy at all scales. Geostrophic and hydrostatic balances are studied by examining correlations between terms in the divergence and vertical momentum equations respectively. Both balances are found to decay as the horizontal scale decreases. It is estimated that geostrophic balance becomes less important at scales smaller than 75 km, and hydrostatic balance becomes less important at scales smaller than 35 km, although more work is required to validate these findings. The implications of these results for high-resolution data assimilation are discussed

Measurement of the angle, temperature and flux of fast electrons emitted from intense laser-solid interactions

High-intensity laser-solid interactions generate relativistic electrons, as well as high-energy (multi-MeV) ions and X-rays. The directionality, spectra and total number of electrons that escape atarget-foil is dependent on the absorption, transport and rear-side sheath conditions. Measuring the electrons escaping the target will aid in improving our understanding of these absorption processes and the rear-surface sheath fields that retard the escaping electrons and accelerate ions via the target normal sheath acceleration (TNSA) mechanism. A comprehensive Geant4 study was performed to help analyse measurements made with a wrap-around diagnostic that surrounds the target and uses differential filtering with a FUJI-film image plate detector. The contribution of secondary sources such as X-rays and protons to the measured signal have been taken into account to aid in the retrieval of the electron signal. Angular and spectral data from a high-intensity laser-solid interaction are presented and accompanied by simulations. The total number of emitted electrons has been measured as 2.6 × 1013 with an estimated total energy of 12 ± 1 J from a 100 mu;m Cu target with140 J of incident laser energy during a 4 × 1020 W cm-2 interaction

A methodology to objectively assess the performance of sound field amplification systems demonstrated using fifty physical simulations of classrooms

Introduction: The effect of a sound reinforcement system, in terms of speech intelligibility, has been systematically determined under realistic conditions. Different combinations of ambient and reverberant conditions representative of a classroom environment have been investigated. Materials and Methods: By comparing the measured speech transmission index metric with and without the system in the same space under different room acoustics conditions, it was possible to determine when the system was most effective. A new simple criterion, equivalent noise reduction (ENR), was introduced to determine the effectiveness of the sound reinforcement system which can be used to predict the speech transmission index based on the ambient sound pressure and reverberation time with and without amplification. Results: This criterion had a correlation, R2>0.97. It was found that sound reinforcement provided no benefit if the competing noise level was less than 40 dBA. However, the maximum benefit of such a system was equivalent to a 7.7 dBA noise reduction. Conclusion: Using the ENR model, it would be possible to determine the suitability of implementing sound reinforcement systems in any room, thus providing a tool to determine if natural acoustic treatment or sound field amplification would be of most benefit to the occupants of any particular room

On discretization in time in simulations of particulate flows

We propose a time discretization scheme for a class of ordinary differential equations arising in simulations of fluid/particle flows. The scheme is intended to work robustly in the lubrication regime when the distance between two particles immersed in the fluid or between a particle and the wall tends to zero. The idea consists in introducing a small threshold for the particle-wall distance below which the real trajectory of the particle is replaced by an approximated one where the distance is kept equal to the threshold value. The error of this approximation is estimated both theoretically and by numerical experiments. Our time marching scheme can be easily incorporated into a full simulation method where the velocity of the fluid is obtained by a numerical solution to Stokes or Navier-Stokes equations. We also provide a derivation of the asymptotic expansion for the lubrication force (used in our numerical experiments) acting on a disk immersed in a Newtonian fluid and approaching the wall. The method of this derivation is new and can be easily adapted to other cases

Adaptive Evolution of the Myo6 Gene in Old World Fruit Bats (Family: Pteropodidae)

PMCID: PMC3631194This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Adjunctive granulocyte colony-stimulating factor for treatment of septic shock due to melioidosis

1427 E 60TH ST, CHICAGO, USA, IL, 60637-295

Unfinished Business: Water, Sanitation and Hygiene in Remote Indigenous Communities in Australia's Northern Territory

Improving water, sanitation and hygiene (WASH) outcomes for the ~60,000 Indigenous people living in remote communities in Australia's Northern Territory (NT) remains an important but unresolved policy challenge. Despite major national reforms aimed at bolstering Australia's water security over the last decade, the WASH situation in remote Indigenous communities (RICs) has attracted little attention. This study sheds new light on this issue by assessing the status of WASH indicators (access, behaviours, health outcomes) and identifying obstacles that constrain progress. Up-to-date information on access to WASH services in RICs in NT is scant. We piece together historical data to deduce that there is now almost universal access to improved water sources and sanitation facilities. At least 90% of dwellings currently have a piped water supply and a private sanitation facility. In the 72 largest communities, the quantity of water used by households is far greater than the Australian average, and regular testing reveals the water supplied is of good microbiological quality. The main infrastructure shortfalls - in terms of access, reliability and safety - can be found in the more than 400 small homeland communities, most of which have a population of less than 50. Notwithstanding nearly universal access to services, the burden of WASH-related diseases remains substantial. Indigenous children in remote communities are twice as likely to be hospitalised for intestinal infection as non-Indigenous children. Environmental enteropathy and prevalence of intestinal parasitic infestation (e.g. Strongyloides) provide further markers of excreta-related disease transmission. Trachoma remains endemic in many RICs despite repeated mass drug administrations. Skin infections are also prevalent, and these are thought to underlie disproportionately high rates of acute glomerulonephritis and acute rheumatic fever, both of which lead to chronic and life-threatening kidney and heart diseases. The WASH landscape in RICs therefore presents a paradox: widespread access to WASH infrastructure but a continued high burden of WASHrelated diseases. The underlying reasons for the situation are complex and inseparable from the entrenched socio-economic disadvantage that characterise many households in RICs. However, evidence points to several proximate causes that contribute to the high burden of WASH-related diseases: (i) problematic hygiene practices; (ii) non-functional health hardware within the home (taps, toilets); and (iii) high household occupancy rates. We conclude that past and current service delivery investments have helped to reduce WASH access disparities between Indigenous and non-Indigenous Australians, but they have failed to close the WASH-related disease gap. If future WASH investments in RICs are to yield optimal health dividends, the broader ecosystem must also be tackled, namely hygiene practices, maintenance of household-level hardware, and overcrowding

Laboratory measurements of resistivity in warm dense plasmas relevant to the microphysics of brown dwarfs

Since the observation of the first brown dwarf in 1995, numerous studies have led to a better understanding of the structures of these objects. Here we present a method for studying material resistivity in warm dense plasmas in the laboratory, which we relate to the microphysics of brown dwarfs through viscosity and electron collisions. Here we use X-ray polarimetry to determine the resistivity of a sulphur-doped plastic target heated to Brown Dwarf conditions by an ultra-intense laser. The resistivity is determined by matching the plasma physics model to the atomic physics calculations of the measured large, positive, polarization. The inferred resistivity is larger than predicted using standard resistivity models, suggesting that these commonly used models will not adequately describe the resistivity of warm dense plasma related to the viscosity of brown dwarfs