Baseline design of the filters for the LAD detector on board LOFT

The Large Observatory for X-ray Timing (LOFT) was one of the M3 missions selected for the phase A study in the ESA's Cosmic Vision program. LOFT is designed to perform high-time-resolution X-ray observations of black holes and neutron stars. The main instrument on the LOFT payload is the Large Area Detector (LAD), a collimated experiment with a nominal effective area of ~10 m 2 @ 8 keV, and a spectral resolution of ~240 eV in the energy band 2-30 keV. These performances are achieved covering a large collecting area with more than 2000 large-area Silicon Drift Detectors (SDDs) each one coupled to a collimator based on lead-glass micro-channel plates. In order to reduce the thermal load onto the detectors, which are open to Sky, and to protect them from out of band radiation, optical-thermal filter will be mounted in front of the SDDs. Different options have been considered for the LAD filters for best compromise between high quantum efficiency and high mechanical robustness. We present the baseline design of the optical-thermal filters, show the nominal performances, and present preliminary test results performed during the phase A study.Comment: Proc. SPIE 9144, Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray, 91446

Using reanalysis data to quantify extreme wind power generation statistics: a 33 year case study in Great Britain

With a rapidly increasing fraction of electricity generation being sourced from wind, extreme wind power generation events such as prolonged periods of low (or high) generation and ramps in generation, are a growing concern for the efficient and secure operation of national power systems. As extreme events occur infrequently, long and reliable meteorological records are required to accurately estimate their characteristics. Recent publications have begun to investigate the use of global meteorological “reanalysis” data sets for power system applications, many of which focus on long-term average statistics such as monthly-mean generation. Here we demonstrate that reanalysis data can also be used to estimate the frequency of relatively short-lived extreme events (including ramping on sub-daily time scales). Verification against 328 surface observation stations across the United Kingdom suggests that near-surface wind variability over spatiotemporal scales greater than around 300 km and 6 h can be faithfully reproduced using reanalysis, with no need for costly dynamical downscaling. A case study is presented in which a state-of-the-art, 33 year reanalysis data set (MERRA, from NASA-GMAO), is used to construct an hourly time series of nationally-aggregated wind power generation in Great Britain (GB), assuming a fixed, modern distribution of wind farms. The resultant generation estimates are highly correlated with recorded data from National Grid in the recent period, both for instantaneous hourly values and for variability over time intervals greater than around 6 h. This 33 year time series is then used to quantify the frequency with which different extreme GB-wide wind power generation events occur, as well as their seasonal and inter-annual variability. Several novel insights into the nature of extreme wind power generation events are described, including (i) that the number of prolonged low or high generation events is well approximated by a Poission-like random process, and (ii) whilst in general there is large seasonal variability, the magnitude of the most extreme ramps is similar in both summer and winter. An up-to-date version of the GB case study data as well as the underlying model are freely available for download from our website: http://www.met.reading.ac.uk/~energymet/data/Cannon2014/

Computational Study Of Molecular Hydrogen In Zeolite Na-A. II. Density Of Rotational States And Inelastic Neutron Scattering Spectra

Part I of this series [J. Chem. Phys. 111, 7599 (1999)] describes a simulation of H(2) adsorbed within zeolite Na-A in which a block Lanczos procedure is used to generate the first several (9) rotational eigenstates of H(2), modeled as a rigid rotor, and equilibrated at a given temperature via Monte Carlo sampling. Here, we show that rotational states are strongly perturbed by the electrostatic fields in the solid. Wave functions and densities of rotational energy states are presented. Simulated neutron spectra are compared with inelastic neutron scattering data. Comparisons are made with IR spectra in which rotational levels may appear due to rovibrational coupling. (C) 2001 American Institute of Physics

Computational Study Of Molecular Hydrogen In Zeolite Na-A. I. Potential Energy Surfaces And Thermodynamic Separation Factors For Ortho And Para Hydrogen

We simulate H-2 adsorbed within zeolite Na-A. We use a block Lanczos procedure to generate the first several (9) rotational eigenstates of the molecule, which is modeled as a rigid, quantum rotor with an anisotropic polarizability and quadrupole moment. The rotor interacts with Na cations and O anions; interaction parameters are chosen semiempirically and the truncation of electrostatic fields is handled with a switching function. A Monte Carlo proceedure is used to sample a set of states based on the canonical distribution. Potential energy surfaces, favorable adsorbtion sites, and distributions of barriers to rotation are analyzed. Separation factors for ortho-parahydrogen are calculated; at low temperatures, these are controlled by the ease of rotational tunneling through barriers. (C) 1999 American Institute of Physics

On the Propagation of Slip Fronts at Frictional Interfaces

The dynamic initiation of sliding at planar interfaces between deformable and rigid solids is studied with particular focus on the speed of the slip front. Recent experimental results showed a close relation between this speed and the local ratio of shear to normal stress measured before slip occurs (static stress ratio). Using a two-dimensional finite element model, we demonstrate, however, that fronts propagating in different directions do not have the same dynamics under similar stress conditions. A lack of correlation is also observed between accelerating and decelerating slip fronts. These effects cannot be entirely associated with static local stresses but call for a dynamic description. Considering a dynamic stress ratio (measured in front of the slip tip) instead of a static one reduces the above-mentioned inconsistencies. However, the effects of the direction and acceleration are still present. To overcome this we propose an energetic criterion that uniquely associates, independently on the direction of propagation and its acceleration, the slip front velocity with the relative rise of the energy density at the slip tip.Comment: 15 pages, 6 figure

Massive transfusion protocol optimization

Hemorrhage is the leading cause of mortality in trauma, accounting for up to 80% of intraoperative trauma mortalities and nearly half of the deaths that occur within 24 hours of traumatic injury. The timely and appropriate administration of blood products in hemorrhage control is paramount to adequate resuscitation efforts. Given the need for rapid delivery of products, appropriate product infusion ratios, and adjunctive therapies for control of hemorrhage and anticoagulation reversal, it is essential that facilities have and maintain a Massive Transfusion Protocol. The goal of this project was to create a Massive Transfusion Protocol for our facility that incorporated current literature, involved buy-in from all involved departments, and optimized blood product ordering and delivery in the emergency setting. To this end, a literature search was performed, and a protocol was drafted which focused on single entry point ordering, and automated product delivery until massive transfusion was halted. Elective orders were also incorporated for easy requesting of coagulation reversal agents and pro-clotting factors. The final draft of the protocol was submitted to the hospital transfusion committee for approval and then incorporated into an EHR order set. Staff training was performed in all involved departments before deployment. Outcome measurement is ongoing but it is anticipated that this updated protocol will decrease time between disposition of major bleed and arrival of blood products at the bedside. It is also expected that this protocol will decrease the amount of crystalloid products given to major bleeding patients by increasing efficiency of blood product delivery

Influence of coral cover and structural complexity on the accuracy of visual surveys of coral-reef fish communities

Using manipulated patch reefs with combinations of varying live-coral cover (low, medium and high) and structural complexity (low and high), common community metrics (abundance, diversity, richness and community composition) collected through standard underwater visual census techniques were compared with exhaustive collections using a fish anaesthetic (clove oil). This study showed that reef condition did not influence underwater visual census estimates at a community level, but reef condition can influence the detectability of some small and cryptic species and thismay be exacerbated if surveys are conducted on a larger scale

Exposure to Household Air Pollution from Biomass-Burning Cookstoves and HbA1c and Diabetic Status Among Honduran Women

Household air pollution from biomass cookstoves is estimated to be responsible for more than two and a half million premature deaths annually, primarily in low and middle‐income countries where cardiometabolic disorders, such as Type II Diabetes, are increasing. Growing evidence supports a link between ambient air pollution and diabetes, but evidence for household air pollution is limited. This cross‐sectional study of 142 women (72 with traditional stoves and 70 with cleaner‐burning Justa stoves) in rural Honduras evaluated the association of exposure to household air pollution (stove type, 24‐hour average kitchen and personal fine particulate matter [PM2.5] mass and black carbon) with glycated hemoglobin (HbA1c) levels and diabetic status based on HbA1c levels. The prevalence ratio (PR) per interquartile range increase in pollution concentration indicated higher prevalence of prediabetes/diabetes (vs normal HbA1c) for all pollutant measures (eg, PR per 84 μg/m3 increase in personal PM2.5, 1.49; 95% confidence interval [CI], 1.11‐2.01). Results for HbA1c as a continuous variable were generally in the hypothesized direction. These results provide some evidence linking household air pollution with the prevalence of prediabetes/diabetes, and, if confirmed, suggest that the global public health impact of household air pollution may be broader than currently estimated