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Search Results: 1 - 10 of 397901 matches for " J. F. Hunter "
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Develop mono-block tooth implants using automate design and FEM analysis
R. Hunter,F. Alister,J. Moller,,J.P. Alister
Archives of Materials Science and Engineering , 2007,
Abstract: Purpose: Purpose of this paper is present a new approach to modelling and design the low cost mono-block dental implants based on the integration of the computer aided techniques. This approach provides the automation of the design process of the mono-block dental implants.Design/methodology/approach: The approach used to develop the modelling and design of the mono-block dental implants are based on the parametrization of the main geometric features of the implants. This approach allows to generate several designs of the implant with different configurations respect to the dimensions, forms and tolerances.Findings: The findings are focused on two main topics. The first one is the minimization of the manufacturing cost and time based on the manufacture process automation. The second one is the integration, in the same informatics platform, of the design, analysis and manufacturing environment.Research limitations/implications: The implications are focused on the development of a new design of mono-block dental implants. One of the main features of this design is associated to the reduction of the surgical stage and their simplification respect to other commercial implants. Practical implications: The main outcomes and implications of this research is the design of a low cost dental implant. This solution is implemented to assist the social programs of oral health.Originality/value: The originality of this research is the design of a new model of mono-block dental implant. The structure of this implant improves the mechanical properties; reduce the manufacturing cost and the surgical complications.
A new approach to modelling and designing mono-block dental implants
R. Hunter,F. Alister,J. M?ller,J. Alister
Journal of Achievements in Materials and Manufacturing Engineering , 2007,
Abstract: Purpose: of this paper is present a new approach to modelling and design the low cost mono-block dental implants based on the integration of the computer aided techniques. This approach provides the automation of the design process of the mono-block dental implants.Design/methodology/approach: The approach used to develop the modelling and design of the mono-block dental implants are based on the parametrization of the main geometric features of the implants. This approach allows to generate several designs of the implant with different configurations respect to the dimensions, forms and tolerances.Findings: The findings are focused on two main topics. The first one is the minimization of the manufacturing cost and time based on the manufacture process automation. The second one is the integration, in the same informatics platform, of the design, analysis and manufacturing environment.Research limitations/implications: The implications are focused on the development of a new design of mono-block dental implants. One of the main features of this design is associated to the reduction of the surgical stage and their simplification respect to other commercial implants.Practical implications: The main outcomes and implications of this research is the design of a low cost dental implant. This solution is implemented to assist the social programs of oral health.Originality/value: The originality of this research is the design of a new model of mono-block dental implant. The structure of this implant improves the mechanical properties; reduce the manufacturing cost and the surgical complications.
GroESL protects superoxide dismutase (SOD)— Deficient cells against oxidative stress and is a chaperone for SOD  [PDF]
Gary J. Hunter, Thérèse Hunter
Health (Health) , 2013, DOI: 10.4236/health.2013.510232
Abstract:

Superoxide dismutase (SOD)-deficient Escherichia coli OX326Acells are protected against chemically-induced oxidative stress by expression of the chaperonin GroESL. This protection is equivalent to expression of superoxide dismutase even though GroESL has no inherent SOD activity. Co-overexpression of GroESL and SOD in the same cells results in higher protein yields of SOD and greater metallation of SOD when compared with expression of SOD alone. Greater metallation results in the higher specific activity of SOD that is observed in heat shock, and is not due to increased synthesis of SOD mRNA or protein.

Elemental analysis of aerosol organic nitrates with electron ionization high-resolution mass spectrometry
A. W. Rollins,J. L. Fry,J. F. Hunter,J. H. Kroll
Atmospheric Measurement Techniques (AMT) & Discussions (AMTD) , 2010,
Abstract: Four hydroxynitrates (R(OH)R'ONO2) representative of atmospheric volatile organic compound (VOC) oxidation products were synthesized, nebulized and sampled into an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS). The resulting mass spectrum was used to evaluate calibration factors for elemental analysis of organic nitrates by AMS, and to determine the distribution of nitrogen in the detected fragments in a search for an AMS signature of organic nitrates. We found that 30% of the detected nitrogen mass is in the NO+ and NO2+ fragments, 12% at NHx+ fragments, 5% at CxHyOzN+ fragments, and 53% at various CxHyN+ fragments. Elemental analysis indicated that nitrogen was detected with higher efficiency than carbon and hydrogen, but oxygen was detected with reduced efficiency compared to previously reported results for a suite of organics which did not include organic nitrates. The results are used to suggest the maximum corrections to ambient O:C and N:C ratios based on AMS measurements.
Elemental analysis of aerosol organic nitrates with electron ionization high-resolution mass spectrometry
A. W. Rollins,J. L. Fry,J. F. Hunter,J. H. Kroll
Atmospheric Measurement Techniques Discussions , 2009,
Abstract: Four hydroxynitrates (R(OH)R'ONO2) representative of atmospheric volatile organic compound (VOC) oxidation products were synthesized, nebulized and sampled into an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS). The resulting mass spectrum was used to evaluate calibration factors for elemental analysis of organic nitrates by AMS, and to determine the distribution of nitrogen in the detected fragments in a search for an AMS signature of organic nitrates. We find that 30% of the detected nitrogen mass is in the NO+ and NO2+ fragments, 12% at NHx+ fragments, 5% at CxHyOzN+ fragments, and 53% at various CxHyN+ fragments. Elemental analysis indicated that nitrogen was detected with higher efficiency than carbon and hydrogen, but oxygen was detected with reduced efficiency compared to previously reported results for a suite of organics which did not include organic nitrates. The results are used to suggest the maximum corrections to ambient O:C and N:C ratios based on AMS measurements.
Online measurements of the emissions of intermediate-volatility and semi-volatile organic compounds from aircraft
E. S. Cross,J. F. Hunter,A. J. Carrasquillo,J. P. Franklin
Atmospheric Chemistry and Physics Discussions , 2013, DOI: 10.5194/acpd-13-8065-2013
Abstract: A detailed understanding of the climate and air quality impacts of aviation requires detailed measurements of the emissions of intermediate-volatility and semi-volatile organic compounds (I/SVOCs) from aircraft. Currently both the amount and chemical composition of aircraft I/SVOC emissions remain poorly characterized. Here we characterize I/SVOC emissions from aircraft, using a novel instrument for the online, quantitative measurement of the mass loading and composition of low-volatility organic vapors. Emissions from the NASA DC8 aircraft were sampled on the ground, 143 m downwind of the engines and characterized as a function of engine power from ground idle (~4% maximum rated thrust) through 85% power. Results show that I/SVOC emissions are highest during engine-idle operating conditions, with decreasing but non-zero I/SVOC emissions at higher engine powers. Comparison of I/SVOC emissions with total hydrocarbon (THC) measurements, VOC measurements, and an established emissions profile indicates that I/SVOCs comprise 10–20% of the total organic gas phase emissions at idle, and an increasing fraction of the total gas phase organic emissions at higher powers. Positive matrix factorization of online mass spectra is used to identify three distinct types of I/SVOC emissions: aliphatic, aromatic and oxygenated. The volatility and chemical composition of the emissions suggest that unburned fuel is the dominant source of I/SVOCs at idle, while pyrolysis products make up an increasing fraction of the I/SVOCs at higher powers. Oxygenated I/SVOC emissions were detected at lower engine powers (≤30%) and may be linked to cracked, partially oxidized or unburned fuel components.
Risk Factors for HIV-1 Seroprevalence Among Family Planning Clients in Dar Es Salaam, Tanzania
Saidi H. Kapiga, Eligius F. Lyamuya, Bea Vuylsteke, Donna Spiegelman, Ulla Larsen, David J. Hunter
African Journal of Reproductive Health , 2000,
Abstract: Between March and September of 1995, women receiving family planning (FP) services in three large clinics in Dar es Salaam, Tanzania were invited to participate in a cross-sectional study. Consenting women were interviewed to obtain information about HIV risk factors, and blood for HIV testing was collected. The prevalence of HIV was 16.9% (95% CI: 14.4%–19.3%). The risk of HIV increased significantly with age. Compared with married women, the risk of HIV was significantly higher among cohabiting women (age-adjusted OR = 2.3; 95% CI = 1.5–3.5) and among women who were single, divorced or widowed (age-adjusted OR = 2.3; 95% CI = 1.2–4.4). The risk of HIV was also significantly higher among hotel workers (age-adjusted OR = 4.3; 95% CI = 1.4–12.9). Women with laboratory evidence of sexually transmitted diseases were at increased risk of HIV. This study shows that HIV is a major public health problem among FP clients in Tanzania. Innovative HIV interventions are needed to reduce further spread of HIV infection. (Afr J Reprod Health 2000; 4 [1]: 88-99) Key Words: HIV, women, family planning, prevalence, risk factors, Tanzania, Africa
Diffuse Ionized Gas in Spiral Galaxies: Probing Photon Leakage from HII Regions?
Annette M. N. Ferguson,Rosemary F. G. Wyse,J. S. Gallagher,Deidre A. Hunter
Physics , 1996,
Abstract: As part of a large study to map the distribution of star formation across galactic disks, we have obtained deep Halpha images of the nearby Sculptor Group spirals NGC 247 and NGC 7793. These images are of sufficiently high quality that they allow identification and analysis of diffuse Halpha emission at surface brightness levels ranging from those of extremely low density HII regions to those of the local Galactic disk diffuse emission. This paper presents a study of the large scale distribution and global energetics of diffuse ionized gas (DIG) in these galaxies and investigates the association between DIG and discrete HII regions. Our results support the hypothesis that the DIG is photoionized by Lyc photons which leak out of traditional HII regions, and suggest that the local HI column density plays a role in regulating the amount of leakage which can occur. This interpretation has profound implications for the derivation of star-formation rates based on Halpha emission--line fluxes since HII region counts alone will lead to significant underestimates of the true rate. The contribution of the diffuse Halpha component to the total Halpha emission, ie. the diffuse fraction, in these galaxies is found to be similar to values found in other disk galaxies with differing Hubble types and star formation rates. The constancy of the diffuse fraction is rather unexpected and implies that the overall fraction of photons which can leak out of HII regions and ionize the ISM over large scales is relatively invariant from one galaxy to another.
The Origin of Cosmic Rays and the Diffuse Galactic Gamma-Ray Emission
S. W. Digel,S. D. Hunter,I. V. Moskalenko,J. F. Ormes,M. Pohl
Physics , 2001, DOI: 10.1063/1.1419446
Abstract: Cosmic-ray interactions with interstellar gas and photons produce diffuse gamma-ray emission. In this talk we will review the current understanding of this diffuse emission and its relationship to the problem of the origin of cosmic rays. We will discuss the open issues and what progress might be possible with GLAST, which is planned for launch in 2006.
Assessing the performance of eight real-time updating models and procedures for the Brosna River
N. M. Hunter, P. D. Bates, M. S. Horritt, A. P. J. De Roo,M. G. F. Werner
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2005,
Abstract: To translate a point hydrograph forecast into products for use by environmental agencies and civil protection authorities, a hydraulic model is necessary. Typical one- and two-dimensional hydraulic models are able to predict dynamically varying inundation extent, water depth and velocity for river and floodplain reaches up to 100 km in length. However, because of uncertainties over appropriate surface friction parameters, calibration of hydraulic models against observed data is a necessity. The value of different types of data is explored in constraining the predictions of a simple two-dimensional hydraulic model, LISFLOOD-FP. For the January 1995 flooding on the River Meuse, The Netherlands, a flow observation data set has been assembled for the 35-km reach between Borgharen and Maaseik, consisting of Synthetic Aperture Radar and air photo images of inundation extent, downstream stage and discharge hydrographs, two stage hydrographs internal to the model domain and 84 point observations of maximum free surface elevation. The data set thus contains examples of all the types of data that potentially can be used to calibrate flood inundation models. 500 realisations of the model have been conducted with different friction parameterisations and the performance of each realisation has been evaluated against each observed data set. Implementation of the Generalised Likelihood Uncertainty Estimation (GLUE) methodology is then used to determine the value of each data set in constraining the model predictions as well as the reduction in parameter uncertainty resulting from the updating of generalised likelihoods based on multiple data sources.
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