travis knight - Academia.edu (original) (raw)

Papers by travis knight

2005 Annual Conference Proceedings

and Implications Genetic control of fatty acid composition in grain-fed beef calves was evaluated... more and Implications Genetic control of fatty acid composition in grain-fed beef calves was evaluated when the fatty acids are measured on a percentage of lipid basis and on a mg of fatty acid / g of beef basis. Fatty acids of concern for human health (e.g. 14:0, 16:0, 16:1, 18:0, and 18:1) show evidence of having genetic control. Heritability estimates for these five fatty acids indicate stronger genetic control when fatty acid concentrations are expressed on a percentage of lipid basis (h 2 = 0.20 to 0.49) than when expressed on a mg of fatty acid / g of beef basis (h 2 = 0.12 to 0.27). However, there may be some concern that selection for a healthier fatty acid composition may come through an overall decrease of lipid within the beef. This would have significant consequences for production of high quality beef in the U.S. Our goal was to identify tools which will allow for selection of a healthier fatty acid profile with similar or increased lipid within beef. The results of this study indicate that a selection scheme based on fatty acids expressed on a percentage of lipid basis with maintenance of lipid concentration as a selection goal would be the most likely selection scheme to utilize for improving the healthfulness of U.S. beef.

We propose to improve the fatty acid composition of beef by capitalizing on the natural genetic d... more We propose to improve the fatty acid composition of beef by capitalizing on the natural genetic differences among animals. It is our thought that improvements in the healthfulness of the fatty acid composition of beef can be made while maintaining other positive attributes. Stearoyl-CoA desaturase is responsible for the conversion of 16:0 and 18:0 to 16:1 and 18:1, respectively, the two major monounsaturated fatty acids of bovine lipids.

The current prototype for the front-most car contains cameras, LED lighting, two lasers for local... more The current prototype for the front-most car contains cameras, LED lighting, two lasers for localization, and EMATs.

AIP Conference Proceedings

Very low specific-mass power generation in space is possible using Vapor Core Reactors with Magne... more Very low specific-mass power generation in space is possible using Vapor Core Reactors with Magnetohydrodynamic (VCR/MHD) generator. These advanced reactors at the conceptual design level have potential for the generation of tens to hundreds of megawatts of power in space with specific mass of about 1 kg/kWe. Power for nuclear electric propulsion (NEP) is possible with almost direct power conditioning and coupling of the VCR/MHD power output to the VASIMR engine, MPD, and a whole host of electric thrusters. The VCR/MHD based NEP system is designed to power space transportation systems that dramatically reduce the mission time for human exploration of the entire solar system or for aggressive long-term robotic missions. There are more than 40 years of experience in the evaluation of the scientific and technical feasibility of gas and vapor core reactor concepts. The proposed VCR is based on the concept of a cavity reactor made critical through the use of a reflector such as beryllium or beryllium oxide. Vapor fueled cavity reactors that are considered for NEP applications operate at maximum core center and wall temperatures of 4000 K and 1500K, respectively. A recent investigation has resulted in the conceptual design of a uranium tetrafluoride fueled vapor core reactor coupled to a MHD generator. Detailed neutronic design and cycle analyses have been performed to establish the operating design parameters for 10 to 200 MWe NEP systems. An integral system engineering-simulation code is developed to perform parametric analysis and design optimization studies for the VCR/MHD power system. Total system weight and size calculated based on existing technology has proven the feasibility of achieving exceptionally low specific mass (alpha ~1 kg/kWe) with a VCR/MHD powered system.

AIP Conference Proceedings

Current work modeling high temperature compact heat exchangers may demonstrate the design feasibi... more Current work modeling high temperature compact heat exchangers may demonstrate the design feasibility of a Vapor Core Reactor (VCR) driven combined cycle power plant. For solid nuclear fuel designs, the cycle efficiency is typically limited by a metallurgical temperature limit which is dictated by fuel and structural melting points. In a vapor core, the gas/vapor phase nuclear fuel is uniformly mixed with the topping cycle working fluid. Heat is generated homogeneously throughout the working fluid thus extending the metallurgical temperature limit. Because of the high temperature, magnetohydrodynamic (MHD) generation is employed for topping cycle power extraction. MHD rejected heat is transported via compact heat exchanger to a conventional Brayton gas turbine bottoming cycle. High bottoming cycle mass flow rates are required to remove the waste heat because of low heat capacities for the bottoming cycle gas. High mass flow is also necessary to balance the high Uranium Tetrafluoride (UF) mass flow rate in the topping cycle. Heat exchanger design is critical due to the high temperatures and corrosive influence of fluoride compounds and fission products existing in VCR/MHD exhaust. Working fluid compositions for the topping cycle include variations of Uranium Tetrafluoride, Helium and various electrical conductivity seeds for the MHD. Bottoming cycle working fluid compositions include variations of Helium and Xenon. Some thought has been given to include liquid metal vapor in the bottoming cycle for a Cheng or evaporative cooled design enhancement. The NASA Glenn Lewis Research Center code Chemical Equilibrium with Applications (CEA) is utilized for evaluating chemical species existing in the gas stream. Work being conducted demonstrates the compact heat exchanger design, utilization of the CEA code, and assessment of different topping and bottoming working fluid compositions. (authors)

The purpose of this study is to modify adipose cells genetically in culture to produce cells that... more The purpose of this study is to modify adipose cells genetically in culture to produce cells that contain less saturated fat. To accomplish this objective, a fatty acid desaturase gene from castor beans will be transferred into adipose cells. Using cultured liver cells as a test system, the gene was successfully transferred into 12 different cultures of liver cells. We are currently studying the production of the corresponding RNA from the incorporated gene and the fatty acid composition of the transformed cells. Our next goal is to conduct similar activities using cultured adipose cells. Saturated fatty acids make up 40 to 55% of the total fat associated with meat. It has been demonstrated in animal and human studies that dietary saturated fatty acids (excluding C18:0) are hypercholesterolemic when compared with polyunsaturated fatty acids. Therefore, nutritional scientists must seek with urgency nutritional, managerial, and genetic protocols for decreasing the fat content and the proportion of saturated fatty acids in animal-derived foods.

Transactions of the American Nuclear Society, 2007

Life Sciences, May 1, 1996

The hypothesis was tested that resveratrol, a compound in red wine, would inhibit atherosclerotic... more The hypothesis was tested that resveratrol, a compound in red wine, would inhibit atherosclerotic development in rabbits fed 0.5% cholesterol for 60 days. Rabbits were supplemented with or without oral resveratrol. During the study, body weights and food consumption were similar for the two groups. The lack of differences between liver weights and a series of serum parameters indicative of liver disease suggest that liver function was similar in the two groups. The diet produced hypercholesterolemia in both groups, but no differences in lipoprotein-cholesterol concentrations. The electrophoretic mobility of plasma low-density lipoprotein (LDL) and plasma LDL after induced oxidation also was not different between the groups. Staining of atherosclerotic lesions in the control and resveratrol-treated groups revealed that the resveratrol-treated rabbits had significantly more aortic surface area covered by atherosclerotic lesions (P < 0.02). Therefore, resveratrol promoted atherosclerotic development, rather than protect against it, by a mechanism that is independent of observed differences in gross animal health, liver function, plasma cholesterol concentrations, or LDL oxidative status.

The Journal of neuroscience : the official journal of the Society for Neuroscience, 1988

When stimuli with larger forms (global) containing smaller forms (local) are presented to subject... more When stimuli with larger forms (global) containing smaller forms (local) are presented to subjects with large lesions in the right hemisphere, they are more likely to miss the global form than the local form, whereas subjects with large lesions in the left are more likely to miss the local than the global form. The present study tested whether the global/local impairment in subjects with posterior lesions was due to deficits in controlled attentional processes, passive perceptual processes, or both. Attentional control was examined by measuring reaction time changes when the probability of a target appearing at either the global or local level was varied. Patients with unilateral right or left lesions centered in temporal-parietal regions and age-matched controls served as subjects. Because neurophysiological and neuropsychological evidence have implicated temporal regions in visual discrimination and inferior parietal regions in the allocation of attention to locations in the visua...

Zirconium carbide is being considered as a candidate for inert matrix material in composite nucle... more Zirconium carbide is being considered as a candidate for inert matrix material in composite nuclear fuel for Gas fast reactors due to its favorable characteristics. ZrC can be produced by the direct reaction of pure zirconium and graphite powders. Such a reaction is exothermic in nature. The reaction is self sustaining once initial ignition has been achieved. The heat released

Progress in Nuclear Energy, 2009

Progress in Nuclear Energy, 2010

Progress in Nuclear Energy, 2011

Significant research is currently being performed whereby fast reactor cores have been designed t... more Significant research is currently being performed whereby fast reactor cores have been designed to burn transuranic materials reducing the volume and long-term radiotoxicity of spent nuclear fuel. These core and depletion models depend on various computer codes. This research used MCNPX 2.6.0 and ERANOS 2.1 to model a standard 250 MW Advanced Burner Test Reactor (ABTR) core. The intent was to benchmark criticality and burnup results from a stochastic Monte Carlo code and a deterministic depletion code using a standard ABTR model created by Argonne National Laboratory. Because each of these codes solves the transport and burnup problem differently, there is a need to benchmark the core models in order to verify results and identify root causes for significant differences in results between codes. Flux calculations in ERANOS were performed using diffusion theory, Legendre polynomial approximations (using the VARIANT module) and discrete ordinates methods. The k-effective for the higher order transport models remained within 1000 pcm of the MCNPX model. The difference between the total heavy nuclide mass balance in ERANOS using the various flux calculations and the MCNPX depletion model was less than 0.4% out to a burnup of 1095 days (67.45 GWd/MTHM). The percent delta between the codes as a fraction of the fissioned mass was 1.34%. For the isotopes with large concentrations, such as 238 U and 239 Pu, the mass differences were 0.38% and 0.01% respectively. The mass difference for 241 Am was also small at 0.42%. Notable isotopes in small quantities with larger mass differences were 242 Am, 242 Cm, 243 Cm and 246 Cm where differences ranged from 0.1 to 0.2% after 26 days and increased to 11e136% at 1095 days.

2005 Annual Conference Proceedings

and Implications Genetic control of fatty acid composition in grain-fed beef calves was evaluated... more and Implications Genetic control of fatty acid composition in grain-fed beef calves was evaluated when the fatty acids are measured on a percentage of lipid basis and on a mg of fatty acid / g of beef basis. Fatty acids of concern for human health (e.g. 14:0, 16:0, 16:1, 18:0, and 18:1) show evidence of having genetic control. Heritability estimates for these five fatty acids indicate stronger genetic control when fatty acid concentrations are expressed on a percentage of lipid basis (h 2 = 0.20 to 0.49) than when expressed on a mg of fatty acid / g of beef basis (h 2 = 0.12 to 0.27). However, there may be some concern that selection for a healthier fatty acid composition may come through an overall decrease of lipid within the beef. This would have significant consequences for production of high quality beef in the U.S. Our goal was to identify tools which will allow for selection of a healthier fatty acid profile with similar or increased lipid within beef. The results of this study indicate that a selection scheme based on fatty acids expressed on a percentage of lipid basis with maintenance of lipid concentration as a selection goal would be the most likely selection scheme to utilize for improving the healthfulness of U.S. beef.

We propose to improve the fatty acid composition of beef by capitalizing on the natural genetic d... more We propose to improve the fatty acid composition of beef by capitalizing on the natural genetic differences among animals. It is our thought that improvements in the healthfulness of the fatty acid composition of beef can be made while maintaining other positive attributes. Stearoyl-CoA desaturase is responsible for the conversion of 16:0 and 18:0 to 16:1 and 18:1, respectively, the two major monounsaturated fatty acids of bovine lipids.

The current prototype for the front-most car contains cameras, LED lighting, two lasers for local... more The current prototype for the front-most car contains cameras, LED lighting, two lasers for localization, and EMATs.

AIP Conference Proceedings

Very low specific-mass power generation in space is possible using Vapor Core Reactors with Magne... more Very low specific-mass power generation in space is possible using Vapor Core Reactors with Magnetohydrodynamic (VCR/MHD) generator. These advanced reactors at the conceptual design level have potential for the generation of tens to hundreds of megawatts of power in space with specific mass of about 1 kg/kWe. Power for nuclear electric propulsion (NEP) is possible with almost direct power conditioning and coupling of the VCR/MHD power output to the VASIMR engine, MPD, and a whole host of electric thrusters. The VCR/MHD based NEP system is designed to power space transportation systems that dramatically reduce the mission time for human exploration of the entire solar system or for aggressive long-term robotic missions. There are more than 40 years of experience in the evaluation of the scientific and technical feasibility of gas and vapor core reactor concepts. The proposed VCR is based on the concept of a cavity reactor made critical through the use of a reflector such as beryllium or beryllium oxide. Vapor fueled cavity reactors that are considered for NEP applications operate at maximum core center and wall temperatures of 4000 K and 1500K, respectively. A recent investigation has resulted in the conceptual design of a uranium tetrafluoride fueled vapor core reactor coupled to a MHD generator. Detailed neutronic design and cycle analyses have been performed to establish the operating design parameters for 10 to 200 MWe NEP systems. An integral system engineering-simulation code is developed to perform parametric analysis and design optimization studies for the VCR/MHD power system. Total system weight and size calculated based on existing technology has proven the feasibility of achieving exceptionally low specific mass (alpha ~1 kg/kWe) with a VCR/MHD powered system.

AIP Conference Proceedings

Current work modeling high temperature compact heat exchangers may demonstrate the design feasibi... more Current work modeling high temperature compact heat exchangers may demonstrate the design feasibility of a Vapor Core Reactor (VCR) driven combined cycle power plant. For solid nuclear fuel designs, the cycle efficiency is typically limited by a metallurgical temperature limit which is dictated by fuel and structural melting points. In a vapor core, the gas/vapor phase nuclear fuel is uniformly mixed with the topping cycle working fluid. Heat is generated homogeneously throughout the working fluid thus extending the metallurgical temperature limit. Because of the high temperature, magnetohydrodynamic (MHD) generation is employed for topping cycle power extraction. MHD rejected heat is transported via compact heat exchanger to a conventional Brayton gas turbine bottoming cycle. High bottoming cycle mass flow rates are required to remove the waste heat because of low heat capacities for the bottoming cycle gas. High mass flow is also necessary to balance the high Uranium Tetrafluoride (UF) mass flow rate in the topping cycle. Heat exchanger design is critical due to the high temperatures and corrosive influence of fluoride compounds and fission products existing in VCR/MHD exhaust. Working fluid compositions for the topping cycle include variations of Uranium Tetrafluoride, Helium and various electrical conductivity seeds for the MHD. Bottoming cycle working fluid compositions include variations of Helium and Xenon. Some thought has been given to include liquid metal vapor in the bottoming cycle for a Cheng or evaporative cooled design enhancement. The NASA Glenn Lewis Research Center code Chemical Equilibrium with Applications (CEA) is utilized for evaluating chemical species existing in the gas stream. Work being conducted demonstrates the compact heat exchanger design, utilization of the CEA code, and assessment of different topping and bottoming working fluid compositions. (authors)

The purpose of this study is to modify adipose cells genetically in culture to produce cells that... more The purpose of this study is to modify adipose cells genetically in culture to produce cells that contain less saturated fat. To accomplish this objective, a fatty acid desaturase gene from castor beans will be transferred into adipose cells. Using cultured liver cells as a test system, the gene was successfully transferred into 12 different cultures of liver cells. We are currently studying the production of the corresponding RNA from the incorporated gene and the fatty acid composition of the transformed cells. Our next goal is to conduct similar activities using cultured adipose cells. Saturated fatty acids make up 40 to 55% of the total fat associated with meat. It has been demonstrated in animal and human studies that dietary saturated fatty acids (excluding C18:0) are hypercholesterolemic when compared with polyunsaturated fatty acids. Therefore, nutritional scientists must seek with urgency nutritional, managerial, and genetic protocols for decreasing the fat content and the proportion of saturated fatty acids in animal-derived foods.

Transactions of the American Nuclear Society, 2007

Life Sciences, May 1, 1996

The hypothesis was tested that resveratrol, a compound in red wine, would inhibit atherosclerotic... more The hypothesis was tested that resveratrol, a compound in red wine, would inhibit atherosclerotic development in rabbits fed 0.5% cholesterol for 60 days. Rabbits were supplemented with or without oral resveratrol. During the study, body weights and food consumption were similar for the two groups. The lack of differences between liver weights and a series of serum parameters indicative of liver disease suggest that liver function was similar in the two groups. The diet produced hypercholesterolemia in both groups, but no differences in lipoprotein-cholesterol concentrations. The electrophoretic mobility of plasma low-density lipoprotein (LDL) and plasma LDL after induced oxidation also was not different between the groups. Staining of atherosclerotic lesions in the control and resveratrol-treated groups revealed that the resveratrol-treated rabbits had significantly more aortic surface area covered by atherosclerotic lesions (P < 0.02). Therefore, resveratrol promoted atherosclerotic development, rather than protect against it, by a mechanism that is independent of observed differences in gross animal health, liver function, plasma cholesterol concentrations, or LDL oxidative status.

The Journal of neuroscience : the official journal of the Society for Neuroscience, 1988

When stimuli with larger forms (global) containing smaller forms (local) are presented to subject... more When stimuli with larger forms (global) containing smaller forms (local) are presented to subjects with large lesions in the right hemisphere, they are more likely to miss the global form than the local form, whereas subjects with large lesions in the left are more likely to miss the local than the global form. The present study tested whether the global/local impairment in subjects with posterior lesions was due to deficits in controlled attentional processes, passive perceptual processes, or both. Attentional control was examined by measuring reaction time changes when the probability of a target appearing at either the global or local level was varied. Patients with unilateral right or left lesions centered in temporal-parietal regions and age-matched controls served as subjects. Because neurophysiological and neuropsychological evidence have implicated temporal regions in visual discrimination and inferior parietal regions in the allocation of attention to locations in the visua...

Zirconium carbide is being considered as a candidate for inert matrix material in composite nucle... more Zirconium carbide is being considered as a candidate for inert matrix material in composite nuclear fuel for Gas fast reactors due to its favorable characteristics. ZrC can be produced by the direct reaction of pure zirconium and graphite powders. Such a reaction is exothermic in nature. The reaction is self sustaining once initial ignition has been achieved. The heat released

Progress in Nuclear Energy, 2009

Progress in Nuclear Energy, 2010

Progress in Nuclear Energy, 2011

Significant research is currently being performed whereby fast reactor cores have been designed t... more Significant research is currently being performed whereby fast reactor cores have been designed to burn transuranic materials reducing the volume and long-term radiotoxicity of spent nuclear fuel. These core and depletion models depend on various computer codes. This research used MCNPX 2.6.0 and ERANOS 2.1 to model a standard 250 MW Advanced Burner Test Reactor (ABTR) core. The intent was to benchmark criticality and burnup results from a stochastic Monte Carlo code and a deterministic depletion code using a standard ABTR model created by Argonne National Laboratory. Because each of these codes solves the transport and burnup problem differently, there is a need to benchmark the core models in order to verify results and identify root causes for significant differences in results between codes. Flux calculations in ERANOS were performed using diffusion theory, Legendre polynomial approximations (using the VARIANT module) and discrete ordinates methods. The k-effective for the higher order transport models remained within 1000 pcm of the MCNPX model. The difference between the total heavy nuclide mass balance in ERANOS using the various flux calculations and the MCNPX depletion model was less than 0.4% out to a burnup of 1095 days (67.45 GWd/MTHM). The percent delta between the codes as a fraction of the fissioned mass was 1.34%. For the isotopes with large concentrations, such as 238 U and 239 Pu, the mass differences were 0.38% and 0.01% respectively. The mass difference for 241 Am was also small at 0.42%. Notable isotopes in small quantities with larger mass differences were 242 Am, 242 Cm, 243 Cm and 246 Cm where differences ranged from 0.1 to 0.2% after 26 days and increased to 11e136% at 1095 days.