3,658 research outputs found
Effect of Iodine on Mercury Concentrations in Dental-unit Wastewater
Dental amalgam is a mixture of mercury, silver, tin, and copper. Mercury typically makes up about 50% of it. The amalgam is used to provide the dental patient with a strong durable filling. Some of the dental amalgam may end up in the dental wastewater along with the water used for rinsing. Iodine is often used to control bacteria in dental-unit fresh waterlines. Could Iodine effect mercury concentrations in the wastewater?ISTC partnered with researchers at the Naval Institute for Dental and Biomedical Research to answer that question. Full results appear in Stone, Mark E., et al (2006). "Effect of Iodine on Mercury Concentrations in Dental-unit Wastewater." Dental Materials 22(2), 119-124. https://doi.org/10.1016/j.dental.2005.04.009.Ope
Chemistry and radiative shielding in star forming galactic disks
To understand the conditions under which dense, molecular gas is able to form
within a galaxy, we post-process a series of three-dimensional
galactic-disk-scale simulations with ray-tracing based radiative transfer and
chemical network integration to compute the equilibrium chemical and thermal
state of the gas. In performing these simulations we vary a number of
parameters, such as the ISRF strength, vertical scale height of stellar
sources, cosmic ray flux, to gauge the sensitivity of our results to these
variations. Self-shielding permits significant molecular hydrogen (H2)
abundances in dense filaments around the disk midplane, accounting for
approximately ~10-15% of the total gas mass. Significant CO fractions only form
in the densest, n>~10^3 cm^-3, gas where a combination of dust, H2, and
self-shielding attenuate the FUV background. We additionally compare these
ray-tracing based solutions to photochemistry with complementary models where
photo-shielding is accounted for with locally computed prescriptions. With some
exceptions, these local models for the radiative shielding length perform
reasonably well at reproducing the distribution and amount of molecular gas as
compared with a detailed, global ray tracing calculation. Specifically, an
approach based on the Jeans Length with a T=40K temperature cap performs the
best in regards to a number of different quantitative measures based on the H2
and CO abundances.Comment: 21 Pages, 15 figures. Submitted to MNRAS. Comments welcom
Translating Research Into Practice: Speeding the Adoption of Innovative Health Care Programs
Looks at case studies of four innovative clinical programs to determine key factors influencing the diffusion and adoption of innovations in health care
System and Method for Automated Rendezvous, Docking and Capture of Autonomous Underwater Vehicles
A system for automated rendezvous, docking, and capture of autonomous underwater vehicles at the conclusion of a mission comprising of comprised of a docking rod having lighted, pulsating (in both frequency and light intensity) series of LED light strips thereon, with the LEDs at a known spacing, and the autonomous underwater vehicle specially designed to detect and capture the docking rod and then be lifted structurally by a spherical end strop about which the vehicle can be pivoted and hoisted up (e.g., onto a ship). The method of recovery allows for very routine and reliable automated recovery of an unmanned underwater asset
Concentrated Flow Erodibility for Physically Based Erosion Models: Temporal Variability in Disturbed and Undisturbed Rangelands
Current physically based overland flow erosion models for rangeland application do not separate disturbed and undisturbed conditions in modeling concentrated flow erosion. In this study, concentrated flow simulations on disturbed and undisturbed rangelands were used to estimate the erodibility and to evaluate the performance of linear and power law equations that describe the relationship between erosion rate and several hydraulic parameters. None of the hydraulic parameters consistently predicted the detachment capacity well for all sites, however, stream power performed better than most of other hydraulic parameters. Using power law functions did not improve the detachment relation with respect to that of the linear function. Concentrated flow erodibility increased significantly when a site was exposed to a disturbance such as fire or tree encroachment into sagebrush steppe. This study showed that burning increases erosion by amplifying the erosive power of overland flow through removing obstacles and by changing the soil properties affecting erodibility itself. However, the magnitude of fire impact varied among sites due to inherent differences in site characteristics and variability in burn severity. In most cases we observed concentrated flow erodibility had a high value at overland flow initiation and then started to decline with time due to reduction of sediment availability. Thus we developed an empirical function to predict erodibility variation within a runoff event as a function of cumulative unit discharge. Empirical equations were also developed to predict erodibility variation with time postdisturbance as a function of readily available vegetation cover and surface soil texture data
The microstructure and hardness of Ni-Co-Al-Ti-Cr quinary alloys
The effects of Ni:Co and Al:Ti ratios on the room temperature microstructure, hardness and lattice parameter of twenty-seven quinary Ni-Co-Al-Ti-Cr alloys have been evaluated. All of the alloys exhibited a uniform - microstructure. Differential scanning calorimetry (DSC) showed that the liquidus and solidus temperatures of the alloys increased with greater Al:Ti ratios, decreased with Cr concentration and remained largely unchanged with respect to the Ni:Co ratio. Neutron diffraction measurements of the and lattice parameters revealed that the lattice misfit in all of the alloys was positive and increased with Ti concentration (i.e. lower Al:Ti ratio) regardless of the concentration of Cr, or the ratio of Ni:Co. Importantly, alloys with a Ni:Co ratio of 1:1, were found to have consistently greater lattice misfits than alloys with Ni:Co ratios of either 1:3 or 3:1. The measured lattice misfits were found to be strongly correlated with the Vickers hardness of the alloys, suggesting that lattice misfit plays a key role in the strengthening of - alloys of this type.Rolls-Royce/EPSRC Strategic Partnership (Grant IDs: EP/H022309/1, EP/H500375/1 and EP/ M005607/1)This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.jallcom.2016.07.15
Simulating Radiating and Magnetized Flows in Multi-Dimensions with ZEUS-MP
This paper describes ZEUS-MP, a multi-physics, massively parallel, message-
passing implementation of the ZEUS code. ZEUS-MP differs significantly from the
ZEUS-2D code, the ZEUS-3D code, and an early "version 1" of ZEUS-MP distributed
publicly in 1999. ZEUS-MP offers an MHD algorithm better suited for
multidimensional flows than the ZEUS-2D module by virtue of modifications to
the Method of Characteristics scheme first suggested by Hawley and Stone
(1995), and is shown to compare quite favorably to the TVD scheme described by
Ryu et. al (1998). ZEUS-MP is the first publicly-available ZEUS code to allow
the advection of multiple chemical (or nuclear) species. Radiation hydrodynamic
simulations are enabled via an implicit flux-limited radiation diffusion (FLD)
module. The hydrodynamic, MHD, and FLD modules may be used in one, two, or
three space dimensions. Self gravity may be included either through the
assumption of a GM/r potential or a solution of Poisson's equation using one of
three linear solver packages (conjugate-gradient, multigrid, and FFT) provided
for that purpose. Point-mass potentials are also supported. Because ZEUS-MP is
designed for simulations on parallel computing platforms, considerable
attention is paid to the parallel performance characteristics of each module.
Strong-scaling tests involving pure hydrodynamics (with and without
self-gravity), MHD, and RHD are performed in which large problems (256^3 zones)
are distributed among as many as 1024 processors of an IBM SP3. Parallel
efficiency is a strong function of the amount of communication required between
processors in a given algorithm, but all modules are shown to scale well on up
to 1024 processors for the chosen fixed problem size.Comment: Accepted for publication in the ApJ Supplement. 42 pages with 29
inlined figures; uses emulateapj.sty. Discussions in sections 2 - 4 improved
per referee comments; several figures modified to illustrate grid resolution.
ZEUS-MP source code and documentation available from the Laboratory for
Computational Astrophysics at http://lca.ucsd.edu/codes/currentcodes/zeusmp2
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Mapping and validating predictions of soil bacterial biodiversity using European and national scale datasets
Recent research has highlighted strong correlations between soil edaphic parameters and bacterial biodiversity. Here we seek to explore these relationships across the European Union member states with respect to mapping bacterial biodiversity at the continental scale. As part of the EU FP7 EcoFINDERs project, bacterial communities from 76 soil samples taken across Europe were assessed from eleven countries encompassing Arctic to Southern Mediterranean climes, representing a diverse range of soil types and land uses (grassland, forest and arable land). We found predictable relationships between community biodiversity (ordination site scores) and land use factors as well as soil properties such as pH. Based on the modelled relationship between soil pH and bacterial biodiversity found for the surveyed soils, we were able to predict biodiversity in ∼1000 soils for which soil pH data had been collected as part of national scale monitoring. We then performed interpolative mapping utilising existing EU wide soil pH data to present the first map of bacterial biodiversity across the EU member states. The predictive accuracy of the map was assessed again using the national scale data, but this time contrasting the EU wide spatial predictions with point data on bacterial communities. Generally the maps were useful at predicting broad extremes of biodiversity reflective of low or high pH soils, though predictive accuracy was limited for Britain particularly for organic/acidic soil communities. Spatial accuracy could however be increased by utilising published maps of soil pH calculated using geostatistical approaches at both global and national scales. These findings will contribute to wider efforts to predict and understand the spatial distribution of soil biodiversity at global scales. Further work should focus on enhancing the predictive power of such maps, by harmonising global datasets on soil conditioning parameters, soil properties and biodiversity; and the continued efforts to advance the geostatistical modelling of specific components of soil biodiversity at local to global scales
Survey of Barbell Trajectory and Kinematics of the Snatch Lift from the 2015 World and 2017 Pan-American Weightlifting Championships
Analysis of elite performances is important to elucidate the characteristics of effective weightlifting technique contributing to the highest level of achievement. The general technique of the weightlifting movements is well established. However, it is also apparent that weightlifting technique can differ based on athlete characteristics. Thus, existing technical models may not accurately reflect current technique of top performers or be applied generically to athletes of different skill, size, sex, or ability. Therefore, the purpose of this descriptive study was to update the scientific knowledge of snatch technique of top international weightlifters. This study used video analysis to determine barbell trajectory and kinematics of 319 successful snatch attempts from two major international competitions. Relative frequencies of barbell trajectory types differed based on competition, sex, category, and ranking. No statistical differences were observed among the top-three performers for either sex for most kinematic variables, and there were no overall discernible patterns of effect size differences for individual or clusters of kinematic variables. The results of this study indicate that weightlifting success can be achieved with a variety of technique profiles
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