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Healthcare organizations are required to provide workers with respiratory protection (RP) to mitigate hazardous airborne inhalation exposures. This study sought to better identify gaps that exist between RP guidance and clinical practice to understand issues that would benefit from additional research or clarification.
High resolution large eddy simulations (LES) are performed to study the interaction of a stationary shock with fully developed turbulent flow. Turbulent statistics downstream of the interaction are provided for a range of weakly compressible upstream turbulent Mach numbers
, shock Mach numbers
and Taylor-based Reynolds numbers
. The LES displays minimal Reynolds number effects once an inertial range has developed for
. The inertial range scales of the turbulence are shown to quickly return to isotropy, and downstream of sufficiently strong shocks this process generates a net transfer of energy from transverse into streamwise velocity fluctuations. The streamwise shock displacements are shown to approximately follow a
decay with wavenumber as predicted by linear analysis. In conjunction with other statistics this suggests that the instantaneous interaction of the shock with the upstream turbulence proceeds in an approximately linear manner, but nonlinear effects immediately downstream of the shock significantly modify the flow even at the lowest considered turbulent Mach numbers.
Oldowan sites in primary geological context are rare in the archaeological record. Here we describe the depositional environment of Oldowan occurrences at Kanjera South, Kenya, based on field descriptions and granulometric analysis. Excavations have recovered a large Oldowan artefact sample as well as the oldest substantial sample of archaeological fauna. The deposits at Kanjera South consist of 30 m of fluvial, colluvial and lacustrine sediments. Magneto- and biostratigraphy indicate the Kanjera South Member of the Kanjera Formation was deposited during 2.3–1.92 Ma, with 2.0 Ma being a likely age for the archaeological occurrences. Oldowan artefacts and associated fauna were deposited in the colluvial and alluvial silts and sands of beds KS1–3, in the margins of a lake basin. Field descriptions and granulometric analysis of the sediment fine fraction indicate that sediments from within the main archaeological horizon were emplaced as a combination of tractional and hyperconcentrated flows with limited evidence of debris-flow deposition. This style of deposition is unlikely to significantly erode or disturb the underlying surface, and therefore promotes preservation of surface archaeological accumulations. Hominins were repeatedly attracted to the site locale, and rapid sedimentation, minimal bone weathering and an absence of bone or artefact rounding further indicate that fossils and artefacts were quickly buried.
A narrow bridge of floating ice that connected the Wilkins Ice Shelf, Antarctica, to two confining islands eventually collapsed in early April 2009. In the month preceding the collapse, we observed deformation of the ice bridge by means of satellite imagery and from an in situ GPS station. TerraSAR-X images (acquired in stripmap mode) were used to compile a time series. The ice bridge bent most strongly in its narrowest part (westerly), while the northern end (near Charcot Island) shifted in a northeasterly direction. In the south, the ice bridge experienced compressive strain parallel to its long axis. GPS position data were acquired a little south of the narrowest part of the ice bridge from 19 January 2009. Analysis of these data showed both cyclic and monotonic components of motion. Meteorological data and re-analysis of the output of weather-prediction models indicated that easterly winds were responsible for the cyclic motion component. In particular, wind stress on the rough ice melange that occupied the area to the east exerted significant pressure on the ice bridge. The collapse of the ice bridge began with crack formation in the southern section parallel to the long axis of the ice bridge and led to shattering of the southern part. Ultimately, the narrowest part, only 900 m wide, ruptured. The formation of many small icebergs released energy of >125 ×106 J.
Experiments on the National Ignition Facility show that multi-dimensional effects currently dominate the implosion performance. Low mode implosion symmetry and hydrodynamic instabilities seeded by capsule mounting features appear to be two key limiting factors for implosion performance. One reason these factors have a large impact on the performance of inertial confinement fusion implosions is the high convergence required to achieve high fusion gains. To tackle these problems, a predictable implosion platform is needed meaning experiments must trade-off high gain for performance. LANL has adopted three main approaches to develop a one-dimensional (1D) implosion platform where 1D means measured yield over the 1D clean calculation. A high adiabat, low convergence platform is being developed using beryllium capsules enabling larger case-to-capsule ratios to improve symmetry. The second approach is liquid fuel layers using wetted foam targets. With liquid fuel layers, the implosion convergence can be controlled via the initial vapor pressure set by the target fielding temperature. The last method is double shell targets. For double shells, the smaller inner shell houses the DT fuel and the convergence of this cavity is relatively small compared to hot spot ignition. However, double shell targets have a different set of trade-off versus advantages. Details for each of these approaches are described.
The development of solar acoustic holography over the past decade has opened a major new diagnostic avenue in local helioseismology (Lindsey & Braun 1990; 1997; 2000b). Its application to SOI-MDI data from SOHO has revealed “acoustic moats” surrounding sunspots, “acoustic glories” surrounding complex activeregions, and “acoustic condensations” suggesting the existence of significant seismic anomalies up to 20 Mm beneath active-region photospheres. It has given us the first seismic images of a solar flare, and has uncovered a remarkable anomaly in the statistical distribution of seismic emission from acoustic glories. A review of these and other accomplishments is given by Braun & Lindsey (2000a).
Local helioseismology encompasses remote observations, data analysis, and theoretical modeling of solar oscillations to infer the three-dimensional structure within localized regions of the solar interior. What defines a region as “local” is relative, however, since targets of interest have included sunspots and convective elements with spatial scales ∼10−2R⊙ as well as large-scale plasma flows spanning much of a solar hemisphere. As a relatively new discipline first explored in the 1980s, local helioseismology has two main components: first, a research component to understand the interaction of solar oscillations (acoustic and surface gravity) with perturbations within the Sun and, second, the design and application of methods to infer the properties of the perturbations by modeling the measurements of those waves. Successful applications require a thorough understanding of the physics of the waves and their interaction with in homogeneities inside the Sun. The research component is particularly critical. For example, the types of perturbations found in the Sun can include magnetic fields for which the wave interactions can be quite complicated. Currently, the types of structures most amenable to modeling using local helioseismic measurements consist of isotropic wave-speed perturbations and the three components of plasma flows. Assessing the subsurface magnetic field directly is a challenging, but largely unrealized, goal of the field. While the status of the field is evolving, the determination of plasma flows in the first few tens of Mm below the solar surface remains one of the primary practical applications.
We outline in this chapter the practical applications of, and resulting measurements made with, common local helioseismic methods. Broadly speaking, local helioseismology can be roughly divided into Fourier methods (which operate in the frequency–wave number domain) and cross-covariance based methods (which operate in the space–time domain). The former (Section 6.3) can be considered in many ways as extensions of the analysis of global oscillations (Chapter 5) to localized regions of the Sun.
Hospital Ebola preparation is underway in the United States and other countries; however, the best approach and resources involved are unknown.
To examine costs and challenges associated with hospital Ebola preparation by means of a survey of Society for Healthcare Epidemiology of America (SHEA) members.
Electronic survey of infection prevention experts.
A total of 257 members completed the survey (221 US, 36 international) representing institutions in 41 US states, the District of Columbia, and 18 countries. The 221 US respondents represented 158 (43.1%) of 367 major medical centers that have SHEA members and included 21 (60%) of 35 institutions recently defined by the US Centers for Disease Control and Prevention as Ebola virus disease treatment centers. From October 13 through October 19, 2014, Ebola consumed 80% of hospital epidemiology time and only 30% of routine infection prevention activities were completed. Routine care was delayed in 27% of hospitals evaluating patients for Ebola.
Convenience sample of SHEA members with a moderate response rate.
Hospital Ebola preparations required extraordinary resources, which were diverted from routine infection prevention activities. Patients being evaluated for Ebola faced delays and potential limitations in management of other diseases that are more common in travelers returning from West Africa.
This paper describes the system architecture of a newly constructed radio telescope – the Boolardy engineering test array, which is a prototype of the Australian square kilometre array pathfinder telescope. Phased array feed technology is used to form multiple simultaneous beams per antenna, providing astronomers with unprecedented survey speed. The test array described here is a six-antenna interferometer, fitted with prototype signal processing hardware capable of forming at least nine dual-polarisation beams simultaneously, allowing several square degrees to be imaged in a single pointed observation. The main purpose of the test array is to develop beamforming and wide-field calibration methods for use with the full telescope, but it will also be capable of limited early science demonstrations.
The future of centimetre and metre-wave astronomy lies with the Square Kilometre Array (SKA), a telescope under development by a consortium of 17 countries that will be 50 times more sensitive than any existing radio facility. Most of the key science for the SKA will be addressed through large-area imaging of the Universe at frequencies from a few hundred MHz to a few GHz. The Australian SKA Pathfinder (ASKAP) is a technology demonstrator aimed in the mid-frequency range, and achieves instantaneous wide-area imaging through the development and deployment of phased-array feed systems on parabolic reflectors. The large field-of-view makes ASKAP an unprecedented synoptic telescope that will make substantial advances in SKA key science. ASKAP will be located at the Murchison Radio Observatory in inland Western Australia, one of the most radio-quiet locations on the Earth and one of two sites selected by the international community as a potential location for the SKA. In this paper, we outline an ambitious science program for ASKAP, examining key science such as understanding the evolution, formation and population of galaxies including our own, understanding the magnetic Universe, revealing the transient radio sky and searching for gravitational waves.
Antenatal corticosteroids are used to augment fetal lung maturity in human pregnancy. Dexamethasone (DEX) is also used to treat congenital adrenal hyperplasia of the fetus in early pregnancy. We previously reported effects of synthetic corticosteroids given to sheep in early or late gestation on pregnancy length and fetal cortisol levels and glucocorticoids alter plasma insulin-like growth factor (IGF) and insulin-like growth factor binding protein (IGFBP) concentrations in late pregnancy and reduce fetal weight. The effects of administering DEX in early pregnancy on fetal organ weights and betamethasone (BET) given in late gestation on weights of fetal brain regions or organ development have not been reported. We hypothesized that BET or DEX administration at either stage of pregnancy would have deleterious effects on fetal development and associated hormones. In early pregnancy, DEX was administered as four injections at 12-hourly intervals over 48 h commencing at 40–42 days of gestation (dG). There was no consistent effect on fetal weight, or individual fetal organ weights, except in females at 7 months postnatal age. When BET was administered at 104, 111 and 118 dG, the previously reported reduction in total fetal weight was associated with significant reductions in weights of fetal brain, cerebellum, heart, kidney and liver. Fetal plasma insulin, leptin and triiodothyronine were also reduced at different times in fetal and postnatal life. We conclude that at the amounts given, the sheep fetus is sensitive to maternal administration of synthetic glucocorticoid in late gestation, with effects on growth and metabolic hormones that may persist into postnatal life.
We report in this communication on the photoelectrochemical (PEC) performances of copper tungstate (CuWO4) material class. This study was performed on 2-micron thick samples fabricated using a low-cost co-sputtering deposition process, followed by an 8-hour long annealing at 500°C in argon. Microstructural analysis pointed out that the post-deposition treatment was critical to achieve photocatalytic activity. Subsequent characterizations revealed that polycrystalline CuWO4 photoanodes owned promising characteristics for solar-assisted water splitting, i.e (i) an optical band-gap of 2.2 eV, (ii) a flat-band potential of -0.35 V vs. SCE and (iii) conduction and valence band-edges that straddle water splitting redox potentials. CuWO4 photoanodes generated 400 μA.cm-2 at 1.6V vs. SCE under simulated AM1.5G illumination in 0.33M H3PO4 with virtually no dark current up to this potential. Impedance analysis pointed out that large charge transfer resistances (2,500 Ω.cm2) could be the main weakness of this material class. Current research activity is focused on solving this issue to achieve higher PEC performances.
A Web-based training course with embedded video clips for reducing central line-associated bloodstream infections (CLABSIs) was evaluated and shown to improve clinician knowledge and retention of knowledge over time. To our knowledge, this is the first study to evaluate Web-based CLABSI training as a stand-alone intervention.
This paper deals with new neural networks based harmonics detection approaches to minimize hardware resources needed for FPGA implementation. A simple type of neural network called Adaline is used to build an intelligent Active Power Filter control unit for harmonics current elimination and reactive power compensation. For this purpose, two different approaches called Improved Three-Monophase (ITM) and Two-Phase Flow (TPF) methods are proposed. The ITM method corresponds to a simplified structure of the three-monophase method whereas the TPF method derives from the Synchronous Reference Frame method. Indeed, for both proposed methods, only 50% of Adalines with regard to the original methods is used. The corresponding designs were implemented on a FPGA Stratix II platform through Altera DSP Builder® development tool. After analyzing those two methods with respect to performance and size criteria, a comparative study with the popular p-q and also the direct method is reported. From there, one can notice that the p-q is still the most powerful method for three-phase compensation but the TPF method is the fastest and the most compact in terms of size. An experimental result is shown to validate the feasibility of FPGA implementation of ANN-based harmonics extraction algorithms.
The damage of reactive ion etching to shallow junctions is an important consideration in advanced technology.In this paper, the damage incurred during contact etch is studied, with emphasis on those defects responsible for junction leakage of shallow junctions.Shallow p+/n and n+/p junctions have been prepared with depths of 160 nm.Junction leakage measurements have been made for various amounts of silicon loss up to within 20 nm of the junctions by using a CHF3 + CO2 plasma.The degree of chemical and structural damage has been characterized by using photoluminescence, SIMS, and spreading carrier profiling.
The leakage current density was found to depend strongly on contact area and increase rapidly with junction etch depth after the etched surface has extended to within 80 nm of the junction boundary.The concentration and depth of damage increases with increasing plasma exposure until saturation.Etching induced defects are observed in photoluminescence, and one such defect is identified as a carbon interstitialcy.Enhanced diffusion effects were observed for both chemical contamination from the etch gas and the junction dopants.The spatial distribution of the chemical and structural damage has been found to correlate with the junction leakages.The annealing behavior of damage has also been investigated.
Al-based intermetallic coatings are widely used as bond coats and for oxidation protection of turbine blades and engine components. Here we present and discuss the structural and thermal properties of novel unbalanced-magnetron sputtered Al-based coatings (single-phase intermetallic Al2Au, binary Al-Zr, and nano-structured Al-Zr-Y) developed to protect gamma-TiAl from environmental attack at elevated temperatures. Al-Zr films exhibit a coarse-grained dual-phase Al3Zr2-Al2Zr structure and are nano-structured by alloying with ~5, 10, and 14 at% Y.
Combined dynamic differential-scanning calorimetry and thermogravimetric analyses up to a temperature of 1150 °C reveal that the Al2Au film is very stable with only marginal mass gain from oxidation found between 800 and 1000 °C. High temperature X-ray diffraction shows that this coating retains its (311) texture up to 900 °C where Al2O3 formation leads to the depletion of Al in Al2Au and subsequently the precipitation of intermetallic AlAu. When gamma-TiAl is coated with Al2Au and exposed to cyclic oxidation tests at 750 and 850 °C good oxidation resistance is obtained as a protective oxide layer is formed.
Dual-phase Al3Zr2-Al2Zr coatings form ZrO2 and Al2O3 in oxidizing atmosphere. However, the phase transition from monoclinic (m-)ZrO2 to tetragonal (t-)ZrO2 with the accompanying volume change causes flaking of the oxide. Yttrium addition to the Al-Zr films stabilizes the cubic (c-) and t-ZrO2 and hence avoids the fatal tetragonal-monocline transformation. The thermally grown c-ZrO2 based oxides allow good adhesion to thermal barrier coatings which are themselves based on c-ZrO2.
Two-dimensional passive photodiode matrices are hardly useful for image sensing due to the crosstalk between pixels. This crosstalk makes it difficult to recover information from individual pixels. A switching unit attached to each sensing unit has been the common solution in image sensors (such as in CMOS sensors and in TFT-PiN a-Si photosensors). A novel organic photodiode with voltage-switchable photosensitivity was developed recently. Passive photodiode matrices made with such organic photodiodes can be used for image sensing applications. This circuit simulation study demonstrates an effective scheme to extract images from passive photodiode matrices, concluding that individual photodiode parameters determine the contrast and resolution of N by M image sensors.
In order to find the next generation thermoelectric (TE) material, we are focussing on the parameter Nv, the degeneracy of the band extrema in semiconductors near the Fermi energy. We attempt to synthesize ‘multivalley’ semiconductors by incorporating tetrahedral anions to introduce structural complexity while maintaining high crystallographic symmetry.
The synthesis and crystal structures of two new compounds that partially fulfill our requirements for potential TE materials are reported. Pb3(PS4)Br3 is monoclinic, space group P21/m with a=9.1531(1)Å, b=10.9508(3)Å, c=12.7953(1)Å and β=111.024(2)°. Pb3(PS4)I1.75Te0.625 crystallizes in the space group R 3 with a=9.4876(4)Å, c=46.189(3)Å. Both structures are built from alternating layers of lead halide and the thiophosphate ion (PS4)3-.