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The initial classic Fontan utilising a direct right atrial appendage to pulmonary artery anastomosis led to numerous complications. Adults with such complications may benefit from conversion to a total cavo-pulmonary connection, the current standard palliation for children with univentricular hearts.
A single institution, retrospective chart review was conducted for all Fontan conversion procedures performed from July, 1999 through January, 2017. Variables analysed included age, sex, reason for Fontan conversion, age at Fontan conversion, and early mortality or heart transplant within 1 year after Fontan conversion.
A total of 41 Fontan conversion patients were identified. Average age at Fontan conversion was 24.5 ± 9.2 years. Dominant left ventricular physiology was present in 37/41 (90.2%) patients. Right-sided heart failure occurred in 39/41 (95.1%) patients and right atrial dilation was present in 33/41 (80.5%) patients. The most common causes for Fontan conversion included atrial arrhythmia in 37/41 (90.2%), NYHA class II HF or greater in 31/41 (75.6%), ventricular dysfunction in 23/41 (56.1%), and cirrhosis or fibrosis in 7/41 (17.1%) patients. Median post-surgical follow-up was 6.2 ± 4.9 years. Survival rates at 30 days, 1 year, and greater than 1-year post-Fontan conversion were 95.1, 92.7, and 87.8%, respectively. Two patients underwent heart transplant: the first within 1 year of Fontan conversion for heart failure and the second at 5.3 years for liver failure.
Fontan conversion should be considered early when atrial arrhythmias become common rather than waiting for severe heart failure to ensue, and Fontan conversion can be accomplished with an acceptable risk profile.
Develop and implement an effective program for hazard analysis and control of waterborne pathogens at a multicampus hospital with clinics.
A longitudinal study. Several-year study including analysis of results from monitoring and tests of 26 building water systems.
Outpatient and inpatient healthcare facilities network.
The hazard analysis and critical control point (HACCP) process was used to develop a water management program (WMP) for the hospital campuses. The HACCP method systematically addressed 3 questions: (1) What are the potential waterborne hazards in the building water systems of these facilities? (2) How are the hazards being controlled? (3) How do we know that the hazards have been controlled? Microbiological and chemical tests of building water samples were used to validate the performance of the WMP; disease surveillance data further validated effective hazard control.
Hazard analysis showed that waterborne pathogens were generally in good control and that the water quality was good in all facilities. The hospital network has had several legionellosis cases that were identified as presumptive hospital acquired, but none was confirmed or substantiated by water testing in follow-up investigations. Building water system studies unrelated to these cases showed that pressure tanks and electronic automatic faucets required additional hazard control.
Application of the HACCP process for long-term building water systems management was practical and effective. The need for critical control point management of temperature, flow, and oxidant (chlorine) residual concentration was emphasized. The process resulted in discovery of water system components requiring additional hazard control.
Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the southern hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21-cm emission from the EoR in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives.
Previous community surveys of the drop out from mental health treatment have been carried out only in the USA and Canada.
To explore mental health treatment drop out in the World Health Organization World Mental Health Surveys.
Representative face-to-face household surveys were conducted among adults in 24 countries. People who reported mental health treatment in the 12 months before interview (n = 8482) were asked about drop out, defined as stopping treatment before the provider wanted.
Overall, drop out was 31.7%: 26.3% in high-income countries, 45.1% in upper-middle-income countries, and 37.6% in low/ lower/middle-income countries. Drop out from psychiatrists was 21.3% overall and similar across country income groups (high 20.3%, upper-middle 23.6%, low/lower-middle 23.8%) but the pattern of drop out across other sectors differed by country income group. Drop out was more likely early in treatment, particularly after the second visit.
Drop out needs to be reduced to ensure effective treatment.
We describe an investigation of 3 postoperative Gordonia bronchialis sternal infections. A nurse anesthetist was identified as the source of the outbreak, her scrubs likely becoming contaminated by her home washing machine. The outbreak ended after disposal of the implicated washing machine. Domestic laundering of surgical scrubs may need reevaluation.
We present a numerical study on effect of temperature on the performance of a waveguide luminescent solar concentrator (LSC). The purpose is to determine how changes in temperature of the ambient environment of an LSC affect device performance. The thermo-optical coefficient of the polymer waveguide is modeled using the well known Prod’homme formulation and applied in a forward Monte Carlo ray-tracing simulation. We show that the number of collected photons decreases almost linearly as the ambient temperature increases from -50 ºC to +50ºC. This behavior is associated with several competing loss mechanisms in the waveguide. For example, increases in optical confinement due to increased refractive index at low temperature are opposed by increases in cone loss (escape loss) of photons. Other competing mechanisms that exhibit temperature dependence are explained in terms of a detailed balance treatment of the LSC as a function of temperature.
In an effort to better understand the structural changes occurring during hydrogen loading of erbium target materials, we have performed in situ D2 loading of erbium metal (powder) at temperature (450°C) with simultaneous neutron diffraction analysis. This experiment tracked the conversion of Er metal to the α erbium deuteride (solid-solution) phase and then into the β (fluorite) phase. Complete conversion to ErD2.0 was accomplished at 10 Torr D2 pressure with deuterium fully occupying the tetrahedral sites in the fluorite lattice.
The in-situ diffusion experiment was conducted at AECL's Underground Research Laboratory (URL) to improve the understanding of diffusive solute transport in sparsely fractured or intact granitic rock (SFR). The experimental program used a comparative series of laboratory and in-situ field experiments to evaluate the ability of laboratory measurements to estimate in-situ rock properties and to explore issues surrounding the influence of stress relaxation, rock texture, porosity, pore geometry, and anisotropy on derived effective diffusion coefficients (De). In-situ experiments yielded iodide Debetween 1.4 × 10−13 and 1.1 × 10−12 m2/s. Unlike laboratory results, the in-situ De estimates did not exhibit correlation with sample depth or varied stress regime. Laboratory-derived measurements of De, porosity and permeability were found to systematically increase for samples removed from greater depths and higher stress regimes. Laboratory-derived iodide De values consistently trended higher than in-situ values by a factor of 1 to 15, except on the shallowest 240-m Level (σ1 ≍ 30 MPa) where differences were negligible. Laboratory-derived estimates of permeability were consistently higher than in-situ derived values by a factor of 2 to 100. This experimental program provides evidence that laboratory steady-state diffusion experiments are most likely to yield conservative values of De for simulation of diffusive mass transport in SFR.
The evaporation of a range of synthetic pore water solutions representative of the potential high-level-nuclear-waste repository at Yucca Mountain, NV is being investigated. The motivation of this work is to understand and predict the range of brine compositions that may contact the wastecontainers from evaporation of pore waters, because these brines could form corrosive thin films on the containers and impact their long-term integrity. A relatively complex synthetic Topopah Spring Tuff pore water was progressively concentrated by evaporation in a closed vessel, heated to 95°C in a series of sequential experiments. Periodic samples of the evaporating solution were taken to determine the evolving water chemistry. According to chemical divide theory at 25°C and 95°C our starting solution should evolve towards a high pH carbonate brine. Results at 95°C show that this solution evolves towardsa complex brinethat contains about 99 mol% Na+for the cations, and 71 mol% Cl-, 18 mol% ΣCO2(aq), 9 mol% SO42- for the anions. Initial modeling ofthe evaporating solution indicates precipitation of aragonite, halite, silica, sulfate and fluoride phases. The experiments have been used to benchmark the use of the EQ3/6 geochemical code in predicting the evolution of carbonate-rich brines during evaporation.
We present an approach for spectroscopic strain analysis in semiconductor quantum-well devices. This approach is applicable to all types of semiconductor materials, and to spectroscopic techniques which employ the electronic band-structure of the material, such as photoluminescence, photoreflection, photocurrent, and transmittance. The approach is based on two components, namely the theoretical calculation of the strain-sensitivity of the spectral positions of the relevant quantum-confined optical transitions within a particular quantum-well, and the spatially resolved measurement of a substantial part of the optical transition sequence within the quantum-well. The primary experimental technique applied in our approach is photocurrent spectroscopy. InAlGaAs/GaAlAs/GaAs, high-power lasers serve as the model species.
Molecular dynamic simulations were used to identify factors which promote char formation during the thermal degradation of polymers. Computer movies based on these simulations, indicate that cross-linked model polymers tend to undergo further cross-linking when burned, eventually forming a high molecular weight, thermally stable char. This prediction was confirmed by char yield measurements made on γ and e - irradiated polyethylene and chemically cross-linked poly(methyl methacrylate).
The development of power MEMS, such as the Microengine being developed at MIT, requires highly stressed structures to achieve high power densities. Material strength is, therefore, a critical issue for the design of such devices. Due to the stochastic nature of the strength of brittle materials, the length scales of the test specimens should be close to those of the structure in order to avoid excessive extrapolation of the test data. In this paper, strength characterization and supporting analysis of mesoscale biaxial flexure and radiused hub flexure single crystal silicon specimens are presented. The Weibull reference strength' of planar biaxial flexure specimens was found to lie in the range 1.2 to 4.6 GPa, depending on the surface quality. The local strength at stress concentrations was obtained by testing radiused hub flexure specimens. For the case of deep reactive ion etched (DRIE) specimens, the strength at fillet radii was found to be significantly lower than that measured from planar biaxial flexure specimens due to the inferior surface quality in such regions. It was found that strength could be significantly increased by the introduction of an additional isotropic etch after the DRIE step. The test results reported herein have important implications for the development of highly stressed microfabricated structures. The sensitivity of the mechanical strength to surface processing and etching techniques must be accounted for in the design cycle, particular with regard to the selection of the appropriate fabrication route. Furthermore, in the design of highly stressed MEMS devices, it is important to account for the stochastic nature of the material strength.
The redistribution of nitrogen from silicon to the Si-SiO2 interface due to thermal processing is investigated by Secondary Ion Mass Spectroscopy (SIMS) using Metal-Oxide-Semiconductor (MOS) capacitors. SIMS profiles of implanted atomic nitrogen concentration indicate a significant redistribution of the nitrogen, from the silicon to the oxide layer in response to variations of the steady state time and temperature parameters of Rapid Thermal Anneal (RTA) processing. RTA treatment, in N2 ambient, over a temperature range of 750°C - 1100°C, results in a measured increase of the integrated nitrogen peak at the interface. High Frequency Capacitance Voltage (HFCV) measurements of an implanted (N/ 5 × 1014 cm2/s / 26keV) and annealed (900°C / 10s) sample is compared with a control (without N implant) sample to determine the relative nitrogen abundance at the interface. This value corresponds to the increase in fixed oxide charge Q that produces a negative shift in the flat band voltage Vo under negative gate bias conditions.
Nanostructured anodic alumina membranes have been utilized as high-temperature stable supports for 150 nm thick continuous palladium films. The palladium has been deposited by vacuum evaporation onto the rotating substrate. The thermal stability of the resulting compound membranes has been demonstrated for temperatures up to 700ºC under a reducing atmosphere. Hydrogen permeation has been measured up to 280ºC, where the permeability has a value of 2.5·10-7 mol m-2 s-1 Pa-1. At the same time the selectivity factor over carbon dioxide is at least 33.