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University of Texas – Austin
1.
Wang, Andrew Peter.
Wireless power transmission and communication system for implantable devices in rodents.
Degree: MSin Engineering, Electrical Engineering, 2014, University of Texas – Austin
URL: http://hdl.handle.net/2152/39139 
► Measuring physiological changes in rodents helps determine drug safety and efficacy in the pharmaceutical industry. This has led to the miniaturization of implantable devices for…
(more)
▼ Measuring physiological changes in rodents helps determine drug safety and efficacy in the pharmaceutical industry. This has led to the miniaturization of implantable devices for rodents to reduce the physical stress on the animals. The most common power source for implantable devices are batteries, which are heavy, take up space, and need to be replaced. In this thesis, an inductive power and communication link system has been designed to eliminate the need of a battery and reduce the size of the implantable device for rodents. Power is transmitted by inductive coupling from a Helmholtz primary coil, which is wrapped vertically along the rodent’s cage, to the implant secondary coil. Communication from the implant to the base station is achieved by impedance modulation of the implant transmitter coil back to the base station primary coil. This method of communication eliminates the need for a bulky antenna and reduces power consumption. The proposed design can successfully power the implant in a 5350cc cage while it sends temperature data to the base station at 10Hz. The implant is 1.32cc in size and consumes 10.25mW of power while taking and transmitting temperature data.
Advisors/Committee Members: Valvano, Jonathan W., 1953- (advisor), Pearce, John A., 1946- (advisor).
Subjects/Keywords: Wireless power transmission; Implantable devices
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APA (6th Edition):
Wang, A. P. (2014). Wireless power transmission and communication system for implantable devices in rodents. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/39139
Chicago Manual of Style (16th Edition):
Wang, Andrew Peter. “Wireless power transmission and communication system for implantable devices in rodents.” 2014. Masters Thesis, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/39139.
MLA Handbook (7th Edition):
Wang, Andrew Peter. “Wireless power transmission and communication system for implantable devices in rodents.” 2014. Web. 23 Jan 2021.
Vancouver:
Wang AP. Wireless power transmission and communication system for implantable devices in rodents. [Internet] [Masters thesis]. University of Texas – Austin; 2014. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/39139.
Council of Science Editors:
Wang AP. Wireless power transmission and communication system for implantable devices in rodents. [Masters Thesis]. University of Texas – Austin; 2014. Available from: http://hdl.handle.net/2152/39139
University of Texas – Austin
2.
Gopinath, Ajay, 1980-.
Feature modeling and tomographic reconstruction of electron microscopy images.
Degree: PhD, Electrical and Computer Engineering, 2012, University of Texas – Austin
URL: http://hdl.handle.net/2152/ETD-UT-2012-05-4972
► This work introduces a combination of image processing and analysis methods that perform feature extraction, shape analysis and tomographic reconstruction of Electron Microscopy images. These…
(more)
▼ This work introduces a combination of image processing and analysis
methods that perform feature extraction, shape analysis and tomographic reconstruction of Electron Microscopy images. These have been implemented on
images of the AIDS virus interacting with neutralizing molecules. The AIDS
virus spike is the primary target of drug design as it is directly involved in
infecting host cells. First, a fully automated technique is introduced that can
extract sub-volumes of the AIDS virus spike and be used to build a statistical
model without the need for any user supervision. Such an automatic feature
extraction method can significantly enhance the overall process of shape analysis
of the AIDS virus spike imaged through the electron microscope. Accurate
models of the virus spike will help in the development of better drug design
strategies.
Secondly, a tomographic reconstruction method implemented using a
shape based regularization technique is introduced. Spatial models of known
features in the structure being reconstructed are integrated into the reconstruction
process as regularizers. This regularization scheme is driven locally
through shape information obtained from segmentation and compared with a
known spatial model. This method shows reduced blurring, and an improvement
in the resolution of the reconstructed volume was also measured. It performs better than popular current techniques and can be extended to other tomographic modalities. Improved Electron Tomography reconstructions will provide better structure elucidation and improved feature visualization, which can aid in solving key biological issues.
Advisors/Committee Members: Bovik, Alan C. (Alan Conrad), 1958- (advisor), Ress, David Bruce (advisor), Xu, Guoliang (committee member), Pearce, John (committee member), Ghosh, Joydeep (committee member).
Subjects/Keywords: Electron microscopy; AIDS virus; GP 120 spike; Feature modeling; Tomographic reconstruction; Image processing; Inverse problems
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APA (6th Edition):
Gopinath, Ajay, 1. (2012). Feature modeling and tomographic reconstruction of electron microscopy images. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2012-05-4972
Chicago Manual of Style (16th Edition):
Gopinath, Ajay, 1980-. “Feature modeling and tomographic reconstruction of electron microscopy images.” 2012. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/ETD-UT-2012-05-4972.
MLA Handbook (7th Edition):
Gopinath, Ajay, 1980-. “Feature modeling and tomographic reconstruction of electron microscopy images.” 2012. Web. 23 Jan 2021.
Vancouver:
Gopinath, Ajay 1. Feature modeling and tomographic reconstruction of electron microscopy images. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2012. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/ETD-UT-2012-05-4972.
Council of Science Editors:
Gopinath, Ajay 1. Feature modeling and tomographic reconstruction of electron microscopy images. [Doctoral Dissertation]. University of Texas – Austin; 2012. Available from: http://hdl.handle.net/2152/ETD-UT-2012-05-4972
University of Texas – Austin
3.
-4867-0460.
Radio-frequency metamaterials for cloaking, absorption and wave control.
Degree: PhD, Electrical and Computer Engineering, 2015, University of Texas – Austin
URL: http://hdl.handle.net/2152/46766
► Metamaterial technology has provided us with new tools to explore fascinating applications and physical phenomena. Metamaterials have also inspired many scientists and engineers to think…
(more)
▼ Metamaterial technology has provided us with new tools to explore fascinating applications and physical phenomena. Metamaterials have also inspired many scientists and engineers to think about concepts and ideas under a new light. In this work, we look at ways to use metamaterial technologies to solve modern-day challenges. In particular, we have realized covers enabled by metamaterials and metasurfaces that strongly suppress scattering at all angles, still allowing for field penetration inside the “cloaked” region. This important property opens great opportunities across a multitude of sensor applications. There are many current and forward-looking applications where a sensor with control over its presence to a given environment is of great interest. Advantages of our approach are simplicity of fabrication, resiliency to loss and manufacturing imperfections, extraordinarily low and conformal profile, and natural integration with electronics. In this work, we explore practical applications of our cloaking techniques including: low observability, interference reduction from closely spaced co-located antennas, and reduction or modulation of the scattering of receiving dipole antennas, while maintaining any desired level of received power. With such designs, high-performance sensing and measurement techniques, as well as commercial antenna applications, such as co-site antenna platforms and side-lobe level reduction can be envisioned.
Advisors/Committee Members: Alù, Andrea (advisor), Kerkhoff, Aaron (committee member), Ling, Hao (committee member), Pearce, John (committee member), Yilmaz, Ali (committee member).
Subjects/Keywords: Metamaterials; Metasurfaces; FSS; Active surface; Cloaking; Non-foster; ENZ; Microwave lens; Extraordinary transmission; Low observable antenna; Fundamental bounds; Scattering and absorption of antennas; Receiving antennas; Huygens source; Antenna blockage reduction
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APA (6th Edition):
-4867-0460. (2015). Radio-frequency metamaterials for cloaking, absorption and wave control. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/46766
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Chicago Manual of Style (16th Edition):
-4867-0460. “Radio-frequency metamaterials for cloaking, absorption and wave control.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/46766.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
MLA Handbook (7th Edition):
-4867-0460. “Radio-frequency metamaterials for cloaking, absorption and wave control.” 2015. Web. 23 Jan 2021.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Vancouver:
-4867-0460. Radio-frequency metamaterials for cloaking, absorption and wave control. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/46766.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Council of Science Editors:
-4867-0460. Radio-frequency metamaterials for cloaking, absorption and wave control. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/46766
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
University of Texas – Austin
4.
Davis, Mitchell Alan.
Three dimensional simulation of functional neuro-vascular imaging.
Degree: PhD, Electrical and Computer Engineering, 2014, University of Texas – Austin
URL: http://hdl.handle.net/2152/38225
► Functional optical imaging has become a powerful tool for measuring physiological parameters in the brain without disrupting normal physiology. Fluorescence lifetime imaging (FLIM) has been…
(more)
▼ Functional optical imaging has become a powerful tool for measuring physiological parameters in the brain without disrupting normal physiology. Fluorescence lifetime imaging (FLIM) has been shown to allow near real time mapping of oxygen tension in plasma (pO2), and Laser Speckle Contrast Imaging (LSCI) has been demonstrated to provide qualitative assessments of blood flow in the cortex. However, as both of these methods provide physiological parameters based on the spatial sampling of photons arriving at a detector, it is crucially important to understand either where the photons originated, in the case of FLIM, or which moving particles the photons have sampled, in the case of LSCI. Traditionally, these questions have been difficult to solve because of the heterogeneity of the distribution of particles which contribute to the measured signal. In both FLIM and LSCI, for example, only the light which samples the intravascular space will contribute to the signal. While analytical methods have proven to be successful at predicting the imaging depth of homogeneous materials, they are not able to predict imaging depth when measuring a fluorophore or a moving particle that is only present inside blood vessels. Unlike analytical methods, numerical methods can be used to approximate light propagation in an arbitrary geometry. While both deterministic and stochastic models of light propagation can, and have been, successfully employed to determine light fluence in an arbitrary geometry, deterministic methods are not well suited to the task of simulating light propagation in large volumes of turbid media. For this reason, three dimensional Monte Carlo simulations of light propagation combined with high resolution vascular anatomy were used to directly simulate FLIM and LSCI in the brain. Using these simulations, the imaging depth, degree of multiple scattering, and sensitivity of LSCI and FLIM to physiological changes were determined.
Advisors/Committee Members: Dunn, Andrew Kenneth, 1970- (advisor), Pearce, John (committee member), Thomas, Robert (committee member), Tunnell, James (committee member), Ling, Hao (committee member).
Subjects/Keywords: Laser-tissue interactions; Vascular fluorescence imaging; Speckle contrast imaging; Dynamic light scattering; Blood flow imaging
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APA (6th Edition):
Davis, M. A. (2014). Three dimensional simulation of functional neuro-vascular imaging. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/38225
Chicago Manual of Style (16th Edition):
Davis, Mitchell Alan. “Three dimensional simulation of functional neuro-vascular imaging.” 2014. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/38225.
MLA Handbook (7th Edition):
Davis, Mitchell Alan. “Three dimensional simulation of functional neuro-vascular imaging.” 2014. Web. 23 Jan 2021.
Vancouver:
Davis MA. Three dimensional simulation of functional neuro-vascular imaging. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2014. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/38225.
Council of Science Editors:
Davis MA. Three dimensional simulation of functional neuro-vascular imaging. [Doctoral Dissertation]. University of Texas – Austin; 2014. Available from: http://hdl.handle.net/2152/38225
University of Texas – Austin
5.
Nam, Seung Yun.
Ultrasound and photoacoustic imaging to monitor stem cells for tissue regeneration.
Degree: PhD, Electrical and Computer Engineering, 2014, University of Texas – Austin
URL: http://hdl.handle.net/2152/30945
► Regenerative medicine is an interdisciplinary field which has advanced with the use of biotechnologies related to biomaterials, growth factors, and stem cells to replace or…
(more)
▼ Regenerative medicine is an interdisciplinary field which has advanced with the use of biotechnologies related to biomaterials, growth factors, and stem cells to replace or restore damaged cells, tissues, and organs. Among various therapeutic approaches, cell-based therapy is most challenging and exciting for both scientists and clinicians pursuing regenerative medicine. Specifically, stem cells, including mesenchymal stem cells and adipose-derived stem cells, are promising candidate cell types for cell-based therapy because they can differentiate into multiple cell types for tissue regeneration and stimulate other cells through neovascularization or paracrine signaling. Also, for effective treatment using stem cells, the tissue engineered constructs, such as bioactive degradable scaffolds, that provide the physical and chemical cues to guide their differentiation are incorporated with stem cells before implantation. Also, it was previously demonstrated that tissue-engineered matrices can promote tubulogenesis and differentiation of stem cells to vascular cell phenotypes.
Hence, during tissue regeneration after stem cell therapy, there are numerous factors that need to be monitored. As a result, imaging-based stem cell tracking is essential to evaluate the distribution of stem cells as well as to monitor proliferation, differentiation, and interaction with the microenvironment. Therefore, there is a need for a stem cell imaging technique that is not only noninvasive, sensitive, and easy to operate, but also capable of quantitatively assessing stem cell behaviors in the long term with high spatial resolution.
Therefore, the overall goal of this research is to demonstrate a novel imaging method capable of continuous in vitro assessment of stem cells as prepared with tissue engineered constructs and noninvasive longitudinal in vivo monitoring of stem cell behaviors and tissue regeneration after stem cell implantation. In order to accomplish this, gold nanoparticles are demonstrated as photoacoustic imaging contrasts to label stem cells. In addition, ultrasound and photoacoustic imaging was utilized to monitor stem cells and neovascularization in the injured rat tissue. Therefore, using these methods, tissue regeneration can be promoted and noninvasively monitored, resulting in a better understanding of the tissue repair mechanisms following tissue injury.
Advisors/Committee Members: Emelianov, Stanislav Y. (advisor), Suggs, Laura J (committee member), Pearce, John A (committee member), Dunn, Andrew K (committee member), Hall, Neal A (committee member).
Subjects/Keywords: Photoacoustic imaging; Ultrasound imaging; Stem cell; Tissue engineering; Tissue regeneration
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APA (6th Edition):
Nam, S. Y. (2014). Ultrasound and photoacoustic imaging to monitor stem cells for tissue regeneration. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/30945
Chicago Manual of Style (16th Edition):
Nam, Seung Yun. “Ultrasound and photoacoustic imaging to monitor stem cells for tissue regeneration.” 2014. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/30945.
MLA Handbook (7th Edition):
Nam, Seung Yun. “Ultrasound and photoacoustic imaging to monitor stem cells for tissue regeneration.” 2014. Web. 23 Jan 2021.
Vancouver:
Nam SY. Ultrasound and photoacoustic imaging to monitor stem cells for tissue regeneration. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2014. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/30945.
Council of Science Editors:
Nam SY. Ultrasound and photoacoustic imaging to monitor stem cells for tissue regeneration. [Doctoral Dissertation]. University of Texas – Austin; 2014. Available from: http://hdl.handle.net/2152/30945
6.
Larson, Erik Rist.
Admittance measurement for assessment of cardiac hemodynamics in clinical and research applications.
Degree: PhD, Electrical and Computer Engineering, 2012, University of Texas – Austin
URL: http://hdl.handle.net/2152/25100
► The admittance method is an important tool for the indirect determination of cardiac hemodynamics in animal research and has clinical potential as a hemodynamic monitor…
(more)
▼ The admittance method is an important tool for the indirect determination of cardiac hemodynamics in animal research and has clinical potential as a hemodynamic monitor for implantable cardioverter-defibrillators (ICDs). Animal studies use a conductance catheter to determine left-ventricular (LV) volume, but ICDs must make use of existing pacing leads to perform an admittance measurement. This work aims to further the use of the admittance method by extending its use to multi-segment conductance catheters, determining parasitic circuit element's effects on electric property measurements, using biventricular pacing leads to determine cardiac hemodynamics, and analysis of spatial sensitivity using finite element models in various configurations. Experimental results show the admittance method can be used to determine LV stroke volume with biventricular pacing leads. Modeling results show removal of the muscle component focuses the measurement's spatial sensitivity towards the left-ventricular blood pool.
Advisors/Committee Members: Pearce, John A., 1946- (advisor).
Subjects/Keywords: Impedance; Admittance; Biomedical; Instrumentation
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APA (6th Edition):
Larson, E. R. (2012). Admittance measurement for assessment of cardiac hemodynamics in clinical and research applications. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/25100
Chicago Manual of Style (16th Edition):
Larson, Erik Rist. “Admittance measurement for assessment of cardiac hemodynamics in clinical and research applications.” 2012. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/25100.
MLA Handbook (7th Edition):
Larson, Erik Rist. “Admittance measurement for assessment of cardiac hemodynamics in clinical and research applications.” 2012. Web. 23 Jan 2021.
Vancouver:
Larson ER. Admittance measurement for assessment of cardiac hemodynamics in clinical and research applications. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2012. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/25100.
Council of Science Editors:
Larson ER. Admittance measurement for assessment of cardiac hemodynamics in clinical and research applications. [Doctoral Dissertation]. University of Texas – Austin; 2012. Available from: http://hdl.handle.net/2152/25100
7.
Raghavan, Karthik, 1981-.
Design of a wireless bio-telemetric device for measurement of left ventricular pressure-volume loops using the admittance technique in conscious, ambulatory rats.
Degree: PhD, Electrical and Computer Engineering, 2009, University of Texas – Austin
URL: http://hdl.handle.net/2152/18383
► Left ventricular (LV) volume analysis in small animals has proven difficult because of the small size of the hearts and the rapid heart rate. Furthermore,…
(more)
▼ Left ventricular (LV) volume analysis in small animals has proven difficult because of the small size of the hearts and the rapid heart rate. Furthermore, there is a substantial contribution to the signal from both the blood as well as the muscle. Admittance - based measurement techniques has been proven effective in eliminating the muscular component and estimating the blood component accurately. The key factor that makes this measurement effective is the fact that the measurement is made in the complex plane, which measures both the magnitude as well as the phase of the complex phasor. This dissertation presents the design of a wireless telemetric device that measures impedance magnitude and phase measurements along with pressure from conscious, ambulatory rats. Using this impedance data along with other calibration data such as blood resistivity, stroke volume etc., volume is determined.
Advisors/Committee Members: Pearce, John A., 1946- (advisor).
Subjects/Keywords: Heart – Left ventricle – Measurement
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APA (6th Edition):
Raghavan, Karthik, 1. (2009). Design of a wireless bio-telemetric device for measurement of left ventricular pressure-volume loops using the admittance technique in conscious, ambulatory rats. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/18383
Chicago Manual of Style (16th Edition):
Raghavan, Karthik, 1981-. “Design of a wireless bio-telemetric device for measurement of left ventricular pressure-volume loops using the admittance technique in conscious, ambulatory rats.” 2009. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/18383.
MLA Handbook (7th Edition):
Raghavan, Karthik, 1981-. “Design of a wireless bio-telemetric device for measurement of left ventricular pressure-volume loops using the admittance technique in conscious, ambulatory rats.” 2009. Web. 23 Jan 2021.
Vancouver:
Raghavan, Karthik 1. Design of a wireless bio-telemetric device for measurement of left ventricular pressure-volume loops using the admittance technique in conscious, ambulatory rats. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2009. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/18383.
Council of Science Editors:
Raghavan, Karthik 1. Design of a wireless bio-telemetric device for measurement of left ventricular pressure-volume loops using the admittance technique in conscious, ambulatory rats. [Doctoral Dissertation]. University of Texas – Austin; 2009. Available from: http://hdl.handle.net/2152/18383
8.
Davis, Mitchell Alan.
Monte Carlo simulation of fluorescence imaging of microvasculature.
Degree: MSin Engineering, Electrical and Computer Engineering, 2011, University of Texas – Austin
URL: http://hdl.handle.net/2152/ETD-UT-2011-08-4191
► Little numerical analysis has been done on fluorescence lifetime imaging \emph{in-vivo}. Here, a 3D fluorescence Monte Carlo model is used to evaluate a microvasculature geometry…
(more)
▼ Little numerical analysis has been done on fluorescence lifetime imaging \emph{in-vivo}. Here, a 3D fluorescence Monte Carlo model is used to evaluate a microvasculature geometry obtained via two-photon microscopy. I found that a bulk-vascularization assumption does not provide an accurate picture of penetration depth of the collected fluorescence signal. Instead the degree of absorption difference between extravascular and intravascular space, as well as the absorption difference between excitation and emission wavelengths must be taken into account to determine the depth distribution. Additionally, I found that using targeted illumination can provide for superior surface vessel sensitivity over wide-field illumination, with small area detection offering an even greater amount of sensitivity to surface vasculature. Depth sensitivity can be enhanced by either increasing the detector area or increasing the illumination area. Finally, it is shown that the excitation wavelength and vessel size can affect intra-vessel sampling distribution, as well as the amount of signal that originates from inside the vessel under targeted illumination conditions.
Advisors/Committee Members: Dunn, Andrew Kenneth, 1970- (advisor), Pearce, John A., 1946- (advisor).
Subjects/Keywords: Light propagation in tissues
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APA (6th Edition):
Davis, M. A. (2011). Monte Carlo simulation of fluorescence imaging of microvasculature. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-08-4191
Chicago Manual of Style (16th Edition):
Davis, Mitchell Alan. “Monte Carlo simulation of fluorescence imaging of microvasculature.” 2011. Masters Thesis, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/ETD-UT-2011-08-4191.
MLA Handbook (7th Edition):
Davis, Mitchell Alan. “Monte Carlo simulation of fluorescence imaging of microvasculature.” 2011. Web. 23 Jan 2021.
Vancouver:
Davis MA. Monte Carlo simulation of fluorescence imaging of microvasculature. [Internet] [Masters thesis]. University of Texas – Austin; 2011. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-4191.
Council of Science Editors:
Davis MA. Monte Carlo simulation of fluorescence imaging of microvasculature. [Masters Thesis]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-4191
9.
Tatarchuk, John Jacob.
Comparison of soft magnetic materials response to sinusoidal voltage and current excitation.
Degree: MSin Engineering, Electrical and Computer Engineering, 2011, University of Texas – Austin
URL: http://hdl.handle.net/2152/ETD-UT-2011-08-4333
► A pulse hysteresisgraph system was constructed capable outputting current source and voltages source waveforms. MATLAB scripts were created to analyze the collected data. Three toroidal…
(more)
▼ A pulse hysteresisgraph system was constructed capable outputting current source and voltages source waveforms. MATLAB scripts were created to analyze the collected data.
Three toroidal samples of soft magnetic materials were prepared. Theoretical modeling was done to predict the variation of effective applied magnetic fields inside the toroids from ideal assumptions due to three effects: wire spacing, cylindrical spreading, and eddy current generated fields.
Data was collected under sinusoidal voltage source and sinusoidal current source excitation at 1 kHz. Large differences in core loss were noted especially at higher field excitations. Core loss under sinusoidal current source excitation was found to always be greater than or equal to core loss under sinusoidal voltage source. Normal magnetization curves under sinusoidal current and voltage source excitation were also compared. Significant differences were apparent in the magnetization curves of one sample toroid, and slight differences noted in the curves of the other two samples. Eddy currents were offered as a primary mechanism for the difference in core loss between sinusoidal current source and sinusoidal voltage source. A formula to predict the relative eddy current losses to be expected from an arbitrary, periodic voltage waveform shape is given.
Advisors/Committee Members: Wilder, Aleta T. (advisor), Pearce, John A., 1946- (advisor).
Subjects/Keywords: Sinusoidal current source; Sinusoidal voltage source; Soft magnetic materials; Hysteresisgraph; Core loss; Dynamic hysteresis loop; Normal magnetization curve
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APA (6th Edition):
Tatarchuk, J. J. (2011). Comparison of soft magnetic materials response to sinusoidal voltage and current excitation. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-08-4333
Chicago Manual of Style (16th Edition):
Tatarchuk, John Jacob. “Comparison of soft magnetic materials response to sinusoidal voltage and current excitation.” 2011. Masters Thesis, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/ETD-UT-2011-08-4333.
MLA Handbook (7th Edition):
Tatarchuk, John Jacob. “Comparison of soft magnetic materials response to sinusoidal voltage and current excitation.” 2011. Web. 23 Jan 2021.
Vancouver:
Tatarchuk JJ. Comparison of soft magnetic materials response to sinusoidal voltage and current excitation. [Internet] [Masters thesis]. University of Texas – Austin; 2011. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-4333.
Council of Science Editors:
Tatarchuk JJ. Comparison of soft magnetic materials response to sinusoidal voltage and current excitation. [Masters Thesis]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-4333
10.
Shuhatovich, Lev Michael.
Design and implementation of a low-power implantable cardiac monitoring device.
Degree: MSin Engineering, Electrical and Computer Engineering (Circuit Design), 2010, University of Texas – Austin
URL: http://hdl.handle.net/2152/ETD-UT-2010-12-2588
► The conductance catheter technique is commonly used in research to assess cardiac hemodynamics through measurement of ventricular pressure and volume. In order to perform chronic…
(more)
▼ The conductance catheter technique is commonly used in research to assess cardiac hemodynamics through measurement of ventricular pressure and volume. In order to perform chronic cardiac studies in murine rodents, a small low-power device capable of performing these measurements is necessary. This thesis presents the design, implementation, and test of such a device, coupled with a radio that allows for the telemetry to be transmitted to a base station. Multiple low-power design techniques were employed in this device, which is surgically embedded in the animal. The total mass of the device with battery is 4 grams, and the device volume is 10cm3. Results show that it is capable of periodic monitoring of pressure volume loops for up to 60 days on a single charge.
Advisors/Committee Members: Valvano, Jonathan W., 1953- (advisor), Pearce, John A. (committee member).
Subjects/Keywords: Heart; Telemetry; Murine; Cardiology; Rat
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APA (6th Edition):
Shuhatovich, L. M. (2010). Design and implementation of a low-power implantable cardiac monitoring device. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2010-12-2588
Chicago Manual of Style (16th Edition):
Shuhatovich, Lev Michael. “Design and implementation of a low-power implantable cardiac monitoring device.” 2010. Masters Thesis, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/ETD-UT-2010-12-2588.
MLA Handbook (7th Edition):
Shuhatovich, Lev Michael. “Design and implementation of a low-power implantable cardiac monitoring device.” 2010. Web. 23 Jan 2021.
Vancouver:
Shuhatovich LM. Design and implementation of a low-power implantable cardiac monitoring device. [Internet] [Masters thesis]. University of Texas – Austin; 2010. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/ETD-UT-2010-12-2588.
Council of Science Editors:
Shuhatovich LM. Design and implementation of a low-power implantable cardiac monitoring device. [Masters Thesis]. University of Texas – Austin; 2010. Available from: http://hdl.handle.net/2152/ETD-UT-2010-12-2588
11.
Loeffler, Kathryn Rose.
Development of an implantable system to measure the pressure-volume relationship in ambulatory rodent hearts.
Degree: MSin Engineering, Electrical and Computer Engineering, 2012, University of Texas – Austin
URL: http://hdl.handle.net/2152/20018
► The design, fabrication, and in-vivo testing of an implantable device to measure the pressure-volume (PV) relationship in the hearts of conscious, untethered rats is presented.…
(more)
▼ The design, fabrication, and in-vivo testing of an implantable device to measure the pressure-volume (PV) relationship in the hearts of conscious, untethered rats is presented. Volume is measured using a tetrapolar catheter positioned in the left-ventricle which emits a 20kHz current field across the LV blood pool and parallel heart tissue and measures the resulting voltage. The admittance method is used to instantaneously remove the contribution of the parallel heart muscle and Wei’s non-linear blood conductance-to-volume equation is used to calculate volume. Pressure is measured with a strain gauge sensor at the tip of the catheter. The implant was designed to be small, light, and low-power. An average implant occupies 5 cm3, weighs 8g, and on a single charge collects data for 2 months taking 43 samples per day. Collected data is transmitted wirelessly via RF to a base station where it is recorded. The functionality of the implant and measurement system was verified in six rat experiments. In all experiments, ambulatory PV loops were measured on implantation day. Viable pressure data was recorded for 11 days in one rat; in another rat viable admittance data was collected for 10 days. Changing catheter position and non-constant blood resistivity are considered as sources of error in the volume measurement. Pressure drift due to changing atmospheric pressure is considered as a source of error in the pressure measurement. Lastly, alternative uses for the implant and directions for future improvement are considered.
Advisors/Committee Members: Valvano, Jonathan W., 1953- (advisor), Pearce, John A., 1946- (advisor).
Subjects/Keywords: Implant; Low power; Admittance catheter; Conductance catheter; Pressure-volume loop
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APA (6th Edition):
Loeffler, K. R. (2012). Development of an implantable system to measure the pressure-volume relationship in ambulatory rodent hearts. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/20018
Chicago Manual of Style (16th Edition):
Loeffler, Kathryn Rose. “Development of an implantable system to measure the pressure-volume relationship in ambulatory rodent hearts.” 2012. Masters Thesis, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/20018.
MLA Handbook (7th Edition):
Loeffler, Kathryn Rose. “Development of an implantable system to measure the pressure-volume relationship in ambulatory rodent hearts.” 2012. Web. 23 Jan 2021.
Vancouver:
Loeffler KR. Development of an implantable system to measure the pressure-volume relationship in ambulatory rodent hearts. [Internet] [Masters thesis]. University of Texas – Austin; 2012. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/20018.
Council of Science Editors:
Loeffler KR. Development of an implantable system to measure the pressure-volume relationship in ambulatory rodent hearts. [Masters Thesis]. University of Texas – Austin; 2012. Available from: http://hdl.handle.net/2152/20018
12.
Cook, Jason Ray.
Photoacoustic microscopy of nanoparticles in cells and tissues.
Degree: PhD, Biomedical Engineering, 2013, University of Texas – Austin
URL: http://hdl.handle.net/2152/21882
► Molecular photoacoustic imaging is an exciting new field that promises to visualize molecular indicators of disease. The objective of this dissertation is to progress molecular…
(more)
▼ Molecular photoacoustic imaging is an exciting new field that promises to visualize molecular indicators of disease. The objective of this dissertation is to progress molecular imaging by providing a photoacoustic microscopy platform to better validate in vivo molecular photoacoustic imaging, diagnose disease, and study fundamental photoacoustic processes. Initially, a custom photoacoustic microscope was developed to provide high-sensitivity and high-resolution of both endogenous and exogenous contrast agents in thin cell or tissue samples. After characterization, the photoacoustc microscope was first used to image the hemoglobin distribution in the spleen and liver. The photoacoustic microscope was then used to image nanoparticles in injured and diseased cell and tissues samples. These images can be used for in vivo photoacoustic image validation or, independently, as a diagnostic tool for disease. To enhance the utility of photoacoustic microscopy, a quantitation technique was developed for nanoparticles in cells and tissues. Quantitative photoacoustic imaging has the potential to replace mass spectrometry and histology for a wide array of molecular imaging and targeting studies. Finally, photoacoustic microscopy was used to study the nonlinear dependence of the photoacoustic pressure with laser fluence of nanoparticle-loaded cells. New discoveries about the nonlinear dependence with nanoparticle concentration and cell type are presented. These new discoveries may provide the framework for a new type of photoacoustic imaging with contrast that is cell-type specific. Overall, the work described in this dissertation can be used to improve diagnosis and accelerate clinical translation of new and emerging molecular imaging techniques.
Advisors/Committee Members: Emelianov, Stanislav Y. (advisor), Pearce, John A., 1946- (advisor).
Subjects/Keywords: Photoacoustic imaging; Nanoparticles; Quantitative; Histology; Molecular imaging; Microscopy; Nonlinear
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APA (6th Edition):
Cook, J. R. (2013). Photoacoustic microscopy of nanoparticles in cells and tissues. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/21882
Chicago Manual of Style (16th Edition):
Cook, Jason Ray. “Photoacoustic microscopy of nanoparticles in cells and tissues.” 2013. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/21882.
MLA Handbook (7th Edition):
Cook, Jason Ray. “Photoacoustic microscopy of nanoparticles in cells and tissues.” 2013. Web. 23 Jan 2021.
Vancouver:
Cook JR. Photoacoustic microscopy of nanoparticles in cells and tissues. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2013. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/21882.
Council of Science Editors:
Cook JR. Photoacoustic microscopy of nanoparticles in cells and tissues. [Doctoral Dissertation]. University of Texas – Austin; 2013. Available from: http://hdl.handle.net/2152/21882
13.
Gavornik, Jeffrey Peter.
Learning temporal representations in cortical networks through reward dependent expression of synaptic plasticity.
Degree: PhD, Electrical and Computer Engineering, 2009, University of Texas – Austin
URL: http://hdl.handle.net/2152/18394
► The neural basis of the brain's ability to represent time, which is an essential component of cognition, is unknown. Despite extensive behavioral and electrophysiological studies,…
(more)
▼ The neural basis of the brain's ability to represent time, which is an essential component of cognition, is unknown. Despite extensive behavioral and electrophysiological studies, a theoretical framework capable of describing the elementary neural mechanisms used by biological neural networks to learn temporal representations does not exist. It is commonly believed that the underlying cellular mechanisms reside in high order cortical regions and there is an ongoing debate about the neural structures required for temporal processing. Recent experimental studies report sustained neural activity that can represent the timing of expected reward in low-level primary sensory cortices, suggesting that temporal representation may form locally in sensory areas of the cortex. This thesis proposes a theoretical framework that explains how temporal representations of the type seen experimentally can be encoded in local cortical networks and how specific temporal instantiations can be learned through reward modulated synaptic plasticity. The proposed framework asserts that the mechanism responsible for encoding the observed temporal intervals is long-term synaptic potentiation between neurons in a recurrent network. Analytical and numerical techniques are used to demonstrate that the model is sufficient to allow näive networks of both linear and non-linear neurons to encode and reliably represent durations specified by external cues during a training period. Analysis of a non-linear spiking neuron model is accomplished using a mean-field approach. The form of temporal learning described has specific implications that can be confirmed experimentally and these predictions are highlighted. Experimental support for a central component of the model is presented and all of the the results are discussed in relation to current experimental and computational work.
Advisors/Committee Members: Pearce, John A., 1946- (advisor), Shouval, Harel (advisor).
Subjects/Keywords: Brain – Research; Time perception; Neuroplasticity
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APA (6th Edition):
Gavornik, J. P. (2009). Learning temporal representations in cortical networks through reward dependent expression of synaptic plasticity. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/18394
Chicago Manual of Style (16th Edition):
Gavornik, Jeffrey Peter. “Learning temporal representations in cortical networks through reward dependent expression of synaptic plasticity.” 2009. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/18394.
MLA Handbook (7th Edition):
Gavornik, Jeffrey Peter. “Learning temporal representations in cortical networks through reward dependent expression of synaptic plasticity.” 2009. Web. 23 Jan 2021.
Vancouver:
Gavornik JP. Learning temporal representations in cortical networks through reward dependent expression of synaptic plasticity. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2009. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/18394.
Council of Science Editors:
Gavornik JP. Learning temporal representations in cortical networks through reward dependent expression of synaptic plasticity. [Doctoral Dissertation]. University of Texas – Austin; 2009. Available from: http://hdl.handle.net/2152/18394
14.
Yoon, Soon Joon.
Photoacoustic imaging using nanoclusters.
Degree: PhD, Electrical and Computer Engineering, 2017, University of Texas – Austin
URL: http://hdl.handle.net/2152/62064
► Advances in novel imaging techniques and molecular probes are now extending the opportunity of visualizing molecular targets of disease. Molecular imaging provides anatomic as well…
(more)
▼ Advances in novel imaging techniques and molecular probes are now extending the opportunity of visualizing molecular targets of disease. Molecular imaging provides anatomic as well as functional and pathological information to sense the expression of molecular biological events. In general, molecular imaging aims to target a specific cell type or tissue and visualize biological events in vivo at the molecular or cellular levels through specific probes. Molecular imaging is usually performed in conjunction with probes for specific targets. The objective of this dissertation is to explore molecular imaging by providing highly efficient photoacoustic nanocluster contrast agents to further validate in vivo molecular imaging, improve the therapeutic procedure, and study fundamental photoacoustic signal processes from cluster of nanoparticles. Initially, a photothermal stimuli-responsive photoacoustic nanocluster was designed and synthesized to provide highly sensitive dynamic contrast within tissue samples. The photoacoustic signal enhancement from clustering of nanoparticles was demonstrated by characterizing the photoacoustic signal from photothermal stimuli-responsive nanoclusters. After characterization, photothermal stimuli-responsive nanoclusters were injected into a mouse tissue and the dynamic photoacoustic response from the nanoclusters activated by an external laser source was observed. This activation can be repeatedly turned on by modulating input laser signals, suggesting a new route for dynamic photoacoustic contrast imaging that will further improve the imaging contrast and more accurately guide the drug release process. Despite tremendous advantages of using these nanoparticles, their safety in a biological environment could be a major hurdle for their in vivo utilization. In order to avoid accumulation and long-term toxicity of nanoparticles, biodegradable nanoclusters consisting of sub-5 nm primary gold particles stabilized by a weakly adsorbed biodegradable polymer were introduced. The photoacoustic signal from biodegradable nanoclusters was quantitatively characterized. In addition, photothermal stability of different sizes of biodegradable nanoclusters was investigated. These nanoclusters were then intravenously injected into mice and biodistribution of nanoparticles was observed. Finally, in vivo spectroscopic photoacoustic imaging was performed on tumor-bearing mice with antibody conjugated biodegradable nanoclusters. This research may provide a new opportunity for molecular imaging to help diagnose tumors at an early stage and promote clinical translation of these techniques.
Advisors/Committee Members: Emelianov, Stanislav Y. (advisor), Sokolov, Konstantin (committee member), Johnston, Keith (committee member), Pearce, John (committee member), Yu, Edward (committee member).
Subjects/Keywords: Photoacoustic; Nanoparticles; Nanoclusters; Photothermal; Biodegradable
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APA (6th Edition):
Yoon, S. J. (2017). Photoacoustic imaging using nanoclusters. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/62064
Chicago Manual of Style (16th Edition):
Yoon, Soon Joon. “Photoacoustic imaging using nanoclusters.” 2017. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/62064.
MLA Handbook (7th Edition):
Yoon, Soon Joon. “Photoacoustic imaging using nanoclusters.” 2017. Web. 23 Jan 2021.
Vancouver:
Yoon SJ. Photoacoustic imaging using nanoclusters. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2017. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/62064.
Council of Science Editors:
Yoon SJ. Photoacoustic imaging using nanoclusters. [Doctoral Dissertation]. University of Texas – Austin; 2017. Available from: http://hdl.handle.net/2152/62064
15.
Wu, Mingfeng.
Multiple-grid adaptive integral method for general multi-region problems.
Degree: PhD, Electrical and Computer Engineering, 2011, University of Texas – Austin
URL: http://hdl.handle.net/2152/ETD-UT-2011-08-378
► Efficient electromagnetic solvers based on surface integral equations (SIEs) are developed for the analysis of scattering from large-scale and complex composite structures that consist of…
(more)
▼ Efficient electromagnetic solvers based on surface integral equations (SIEs) are developed for the analysis of scattering from large-scale and complex composite structures that consist of piecewise homogeneous magnetodielectric and perfect electrically/magnetically conducting (PEC/PMC) regions. First, a multiple-grid extension of the adaptive integral method (AIM) is presented for multi-region problems. The proposed method accelerates the iterative method-of-moments solution of the pertinent SIEs by employing multiple auxiliary Cartesian grids: If the structure of interest is composed of K homogeneous regions, it introduces K different auxiliary grids. It uses the k
th auxiliary grid first to determine near-zones for the basis functions and then to execute AIM projection/anterpolation, propagation, interpolation, and near-zone pre-correction stages in the k
th region. Thus, the AIM stages are executed a total of K times using different grids and different groups of basis functions. The proposed multiple-grid AIM scheme requires a total of O(N
nz,near+sum({N
k}
Clog{N
k}
C)) operations per iteration, where N
nz,near denotes the total number of near-zone interactions in all regions and {N
k}
C denotes the number of nodes of the k
th Cartesian grid. Numerical results validate the method’s accuracy and reduced complexity for large-scale canonical structures with large numbers of regions (up to 10
6 degrees of freedom and 10
3 regions). Then, a Green function modification approach and a scheme of Hankel- to Teoplitz-matrix conversions are efficiently incorporated to the multiple-grid AIM method to account for a PEC/PMC plane. Theoretical analysis and numerical examples show that, compared to a brute-force imaging scheme, the Green function modification approach reduces the simulation time and memory requirement by a factor of (almost) two or larger if the structure of interest is terminated on or resides above the plane, respectively. In addition, the SIEs are extended to cover structures composed of metamaterial regions, PEC regions, and PEC-material junctions. Moreover, recently introduced well-conditioned SIEs are adopted to achieve faster iterative solver convergence. Comprehensive numerical tests are performed to evaluate the accuracy, computational complexity, and convergence of the novel formulation which is shown to significantly reduce the number of iterations and the overall computational work. Lastly, the efficiency and capabilities of the proposed solvers are demonstrated by solving complex scattering problems, specifically those pertinent to analysis of wave propagation in natural forested environments, the design of metamaterials, and the application of metamaterials to radar cross section reduction.
Advisors/Committee Members: Yilmaz, Ali E. (advisor), Ling, Hao (committee member), Pearce, John (committee member), Alu, Andrea (committee member), Ying, Lexing (committee member).
Subjects/Keywords: Computational electromagnetics; Surface integral equations; Method of moments; Adaptive integral method; Composite structure; Wave propagation; Wave scattering; Metamaterial
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APA (6th Edition):
Wu, M. (2011). Multiple-grid adaptive integral method for general multi-region problems. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-08-378
Chicago Manual of Style (16th Edition):
Wu, Mingfeng. “Multiple-grid adaptive integral method for general multi-region problems.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/ETD-UT-2011-08-378.
MLA Handbook (7th Edition):
Wu, Mingfeng. “Multiple-grid adaptive integral method for general multi-region problems.” 2011. Web. 23 Jan 2021.
Vancouver:
Wu M. Multiple-grid adaptive integral method for general multi-region problems. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-378.
Council of Science Editors:
Wu M. Multiple-grid adaptive integral method for general multi-region problems. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-378
University of Texas – Austin
16.
Protsenko, Dmitriy Evgenievich.
Electrosurgical tissue resection: a numerical study.
Degree: PhD, Biomedical Engineering, 2002, University of Texas – Austin
URL: http://hdl.handle.net/2152/852
► The nature of the electrical, thermal mechanical and chemical phenomena associated with an electrosurgical resection of biological tissues is an important aspect of general surgery…
(more)
▼ The nature of the electrical, thermal mechanical and chemical phenomena
associated with an electrosurgical resection of biological tissues is an important
aspect of general surgery and other specialized medical treatments. A better
understanding of the phenomena and the ability to model them are indispensable if
advancements in the state of the art are to be achieved. This study particularly
emphasizes two of the phenomena that have significant influence on the outcome of
the electrosurgical procedure. These are the nature of the electric contact between
tissue and electrosurgical scalpel and the mechanism of tissue water vaporization and
subsequent mechanical damage to the tissue due to interstitial formation of the vapor
micro bubbles and vacuoles.
A numerical model of the interaction between tissue and electrosurgical
scalpel was used to study the vaporization process at a number of power settings and
for different scalpel geometries. An electric discharge striking between tissue and
electrode was investigated and incorporated into an analytical model used for
numerical simulation. For the water vaporization effect, surface evaporation at the
tissue scalpel contact area and bulk vapor nucleation are introduced to facilitate the
modeling of the change in tissue thermal and electric properties and tissue mechanical
and thermal damage. A number of physical experiments were performed on beef
muscle and saline and water samples to establish experimental values for the
numerical model and observe electric circuit parameters, temperature variations and
thermal damage cause by the electrosurgical current. These results are compared to
those obtained from the simulations performed for the tissue-scalpel electric contact
achieved by means of electric sparks, pure mechanical and mixed spark-mechanical
contact. The simulation results for the contact through sparks alone are in least
agreement and for the pure mechanical contact are in reasonably good agreement with
those observed experimentally. It is reasonable to conclude that the sparks do not
dominate the process of electrosurgical tissue resection though they contribute to
formation of tissue thermal damage.
Advisors/Committee Members: Pearce, John A., 1946- (advisor).
Subjects/Keywords: Electrosurgery; Tissues – Thermal properties; Tissues – Electric properties
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APA (6th Edition):
Protsenko, D. E. (2002). Electrosurgical tissue resection: a numerical study. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/852
Chicago Manual of Style (16th Edition):
Protsenko, Dmitriy Evgenievich. “Electrosurgical tissue resection: a numerical study.” 2002. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/852.
MLA Handbook (7th Edition):
Protsenko, Dmitriy Evgenievich. “Electrosurgical tissue resection: a numerical study.” 2002. Web. 23 Jan 2021.
Vancouver:
Protsenko DE. Electrosurgical tissue resection: a numerical study. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2002. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/852.
Council of Science Editors:
Protsenko DE. Electrosurgical tissue resection: a numerical study. [Doctoral Dissertation]. University of Texas – Austin; 2002. Available from: http://hdl.handle.net/2152/852
University of Texas – Austin
17.
Kottam, Anil Tharian George, 1979-.
Measurement of electrical admittance to study the onset and progression of myocardial ischemia.
Degree: PhD, Biomedical Engineering, 2007, University of Texas – Austin
URL: http://hdl.handle.net/2152/3726
► The electrical admittance of myocardium can be used to distinguish between stunned, ischemic and necrotic myocardial tissue. Myocardial stunning is the reversible contractile dysfunction following…
(more)
▼ The electrical admittance of myocardium can be used to distinguish between stunned, ischemic and necrotic myocardial tissue. Myocardial stunning is the reversible contractile dysfunction following a brief ischemic episode. This reversible nature is clinically significant and is in contrast to the irreversible myocardial dysfunction that occurs with necrosis. This dissertation aims at developing an instrument to measure myocardial admittance during ischemia and subsequent reperfusion and to study the underlying mechanisms governing the onset and progression of ischemia and stunning. The instrument was tested on Langendorff models of the isolated rat heart that has been subjected to varying durations of global no flow ischemia and subsequent reperfusion. The relative permittivity and conductivity of the myocardium was determined and this could be correlated to the state of the tissue.
Advisors/Committee Members: Pearce, John A., 1946- (advisor).
Subjects/Keywords: Coronary heart disease; Myocardial stunning
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APA (6th Edition):
Kottam, Anil Tharian George, 1. (2007). Measurement of electrical admittance to study the onset and progression of myocardial ischemia. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/3726
Chicago Manual of Style (16th Edition):
Kottam, Anil Tharian George, 1979-. “Measurement of electrical admittance to study the onset and progression of myocardial ischemia.” 2007. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/3726.
MLA Handbook (7th Edition):
Kottam, Anil Tharian George, 1979-. “Measurement of electrical admittance to study the onset and progression of myocardial ischemia.” 2007. Web. 23 Jan 2021.
Vancouver:
Kottam, Anil Tharian George 1. Measurement of electrical admittance to study the onset and progression of myocardial ischemia. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2007. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/3726.
Council of Science Editors:
Kottam, Anil Tharian George 1. Measurement of electrical admittance to study the onset and progression of myocardial ischemia. [Doctoral Dissertation]. University of Texas – Austin; 2007. Available from: http://hdl.handle.net/2152/3726
18.
Holt, Lucas.
Admittance derived stroke volume for determination of hemodynamic stability during atrial and ventricular arrhythmias.
Degree: PhD, Electrical and Computer Engineering, 2018, University of Texas – Austin
URL: http://hdl.handle.net/2152/63812
► Implantable cardioverter defibrillators (ICDs) are medical devices proven to prevent sudden cardiac death due to ventricular arrhythmias. Their decisions are based upon intra-cardiac electrograms (IEGM).…
(more)
▼ Implantable cardioverter defibrillators (ICDs) are medical devices proven to prevent sudden cardiac death due to ventricular arrhythmias. Their decisions are based upon intra-cardiac electrograms (IEGM). This is incomplete information since up to 5% of implantable cardioverter defibrillator (ICD) shocks are inappropriate. Receiving a shock is associated with increased mortality as well as emotional trauma. In contrast, physicians determine whether to shock a patient out of a rapid rhythm by determining if the arrhythmia is hemodynamically unstable or stable. An unstable arrhythmia is identified by decreased forward stroke volume (SV) and resultant low blood pressure (BP). It would be ideal to have beat-by-beat SV available to the ICD to assist in the delivery of therapies. A system that utilizes the right ventricular (RV) shocking lead of an ICD to measure the electrical admittance in the RV is proposed for measuring continuous SV. For this method to work, a signal processing technique to remove noise artifacts related to lead motion and respiration must be developed.
Advisors/Committee Members: Valvano, Jonathan W., 1953- (advisor), Feldman, Marc D. (committee member), Pearce, John A. (committee member), Rylander, Henry G. (committee member), Swartzlander, Earl E. (committee member).
Subjects/Keywords: ICD; Hemodyanmics; FFT; DSP; Signal processing; Arrhythmia
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Manager
APA (6th Edition):
Holt, L. (2018). Admittance derived stroke volume for determination of hemodynamic stability during atrial and ventricular arrhythmias. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/63812
Chicago Manual of Style (16th Edition):
Holt, Lucas. “Admittance derived stroke volume for determination of hemodynamic stability during atrial and ventricular arrhythmias.” 2018. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/63812.
MLA Handbook (7th Edition):
Holt, Lucas. “Admittance derived stroke volume for determination of hemodynamic stability during atrial and ventricular arrhythmias.” 2018. Web. 23 Jan 2021.
Vancouver:
Holt L. Admittance derived stroke volume for determination of hemodynamic stability during atrial and ventricular arrhythmias. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2018. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/63812.
Council of Science Editors:
Holt L. Admittance derived stroke volume for determination of hemodynamic stability during atrial and ventricular arrhythmias. [Doctoral Dissertation]. University of Texas – Austin; 2018. Available from: http://hdl.handle.net/2152/63812
19.
Li, Yang, 1982-.
Investigation of wave propagation and antenna radiation in forested environments.
Degree: PhD, Electrical and Computer Engineering, 2011, University of Texas – Austin
URL: http://hdl.handle.net/2152/ETD-UT-2011-05-3092
► Recently, there is emerging interests in deploying wireless sensor networks in forests for applications such as forest fire detection, environmental monitoring and remote surveillance. One…
(more)
▼ Recently, there is emerging interests in deploying wireless sensor networks in forests for applications such as forest fire detection, environmental monitoring and remote surveillance. One challenge in the design of such networks is to ensure reliable communication between sensors located near the ground and over short distances. However, the propagation mechanisms in this type of scenario are complex and not well understood. Furthermore, the design of antennas that can exploit the resulting propagation mechanisms for optimal power transfer remains an open question.
The objective of this dissertation is to understand wave propagation and antenna radiation in forested environments in the HF/VHF frequency range. To achieve this objective, several forest scaled models are introduced. The first scaled forest model is a periodic metal cut-wire array. The transmission data inside the cut-wire array are simulated and measured. The propagation mechanisms inside the array are extracted. Several interesting propagation phenomena associated with surface waves and leaky waves are observed and explained.
Next, a dielectric rod array consisting of water-filled straws is investigated as a more realistic forest model. Water is chosen since its dielectric constant in the microwave range is close to that of tree trunks in the HF/VHF frequencies. The propagation mechanisms in the water rod array are investigated through scaled model measurements in the laboratory, numerical simulations and an effective medium theory. Randomization effects due to rod spacing and rod height on the propagation mechanisms are also studied.
Finally, the transmission data in a real forest are collected in the HF/VHF frequency range to corroborate the findings from the models. The measurement site is located at Bastrop,
Texas. For comparison, the transmission data are also measured in an open field. The transmission data are processed and the resulting propagation mechanisms are extracted and compared with the model predictions.
As an extension of the propagation study, the potential to achieve directive antenna radiations in a forest is explored. A simple metal cut-wire array environment is considered for ease in modeling. For the case when both the transmit antenna and the receive antenna are embedded inside the array, two design ideas are presented. The first design tries to couple the antenna radiation into the dominant propagation mechanism through phase matching and the second design uses a closely spaced Yagi array to decouple the antenna from its surrounding medium. For the case when the transmit antenna is embedded inside the array and the receive antenna is located outside the array, the leaky wave mechanism is explored to achieve directive radiation. These designs are verified through theoretical predictions, numerical simulations and prototype measurements.
Advisors/Committee Members: Ling, Hao (advisor), Pearce, John (committee member), Yilmaz, Ali (committee member), Alu, Andrea (committee member), Torres-Verdin, Carlos (committee member), Shvets, Gennady (committee member).
Subjects/Keywords: Wave propagation; Antenna radiation; Forested environments; Metal cut-wire array; Dielectric rod array
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APA (6th Edition):
Li, Yang, 1. (2011). Investigation of wave propagation and antenna radiation in forested environments. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-05-3092
Chicago Manual of Style (16th Edition):
Li, Yang, 1982-. “Investigation of wave propagation and antenna radiation in forested environments.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/ETD-UT-2011-05-3092.
MLA Handbook (7th Edition):
Li, Yang, 1982-. “Investigation of wave propagation and antenna radiation in forested environments.” 2011. Web. 23 Jan 2021.
Vancouver:
Li, Yang 1. Investigation of wave propagation and antenna radiation in forested environments. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-3092.
Council of Science Editors:
Li, Yang 1. Investigation of wave propagation and antenna radiation in forested environments. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-3092
20.
Ayazianmavi, Sahar.
Photovoltaic (PV) and fully-integrated implantable CMOS ICs.
Degree: PhD, Electrical and Computer Engineering, 2012, University of Texas – Austin
URL: http://hdl.handle.net/2152/ETD-UT-2012-05-5527
► Today, there is an ever-growing demand for compact, and energy autonomous, implantable biomedical sensors. These devices, which continuously collect in vivo physiological data, are imperative…
(more)
▼ Today, there is an ever-growing demand for compact, and energy autonomous, implantable biomedical sensors. These devices, which continuously collect in vivo physiological data, are imperative in the next generation patient monitoring systems. One of the fundamental challenges in their implementation, besides the obvious size constraints and the tissue-to-electronics biocompatibility impediments, is the efficient means to wirelessly deliver power to them. This work addresses this challenge by demonstrating an energy-autonomous and fully-integrated implantable sensor chip which takes advantage of the existing on-chip photodiodes of a standard CMOS process as photovoltaic (PV) energy-harvesting cells. This 2.5 mm × 2.5 mm chip is capable of harvesting [mu]W’s of power from the ambient light passing through the tissue and performing real-time sensing. This system is also MRI compatible as it includes no magnetic material and requires no RF coil or antennae. In this dissertation, the optical properties of tissue and the capabilities of the CMOS integrated PV cells are studied first. Next, the implementation of an implantable sensor using such PV devices is discussed. The sensor characterizing and the in vitro measurement results using this system, demonstrate the feasibility of monolithically integrated CMOS PV-driven implantable sensors. In addition, they offer an alternative method to create low-cost and mass-deployable energy autonomous ICs in biomedical applications and beyond.
Advisors/Committee Members: Hassibi, Arjang (advisor), Pearce, John A. (committee member), Banerjee, Sanjay K. (committee member), Aziz, Adnan (committee member), Soenen, Eric (committee member).
Subjects/Keywords: Energy harvesting; CMOS; Photovoltaic cell; Neuromorphic; Implantable device; Sub-threshold
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APA (6th Edition):
Ayazianmavi, S. (2012). Photovoltaic (PV) and fully-integrated implantable CMOS ICs. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2012-05-5527
Chicago Manual of Style (16th Edition):
Ayazianmavi, Sahar. “Photovoltaic (PV) and fully-integrated implantable CMOS ICs.” 2012. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/ETD-UT-2012-05-5527.
MLA Handbook (7th Edition):
Ayazianmavi, Sahar. “Photovoltaic (PV) and fully-integrated implantable CMOS ICs.” 2012. Web. 23 Jan 2021.
Vancouver:
Ayazianmavi S. Photovoltaic (PV) and fully-integrated implantable CMOS ICs. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2012. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/ETD-UT-2012-05-5527.
Council of Science Editors:
Ayazianmavi S. Photovoltaic (PV) and fully-integrated implantable CMOS ICs. [Doctoral Dissertation]. University of Texas – Austin; 2012. Available from: http://hdl.handle.net/2152/ETD-UT-2012-05-5527
21.
Kim, Seungsoo.
Ultrasound and photoacoustic imaging for cancer detection and therapy guidance.
Degree: PhD, Biomedical Engineering, 2011, University of Texas – Austin
URL: http://hdl.handle.net/2152/ETD-UT-2011-08-4024
► Cancer has been one of main causes of human deaths for many years. Early detection of cancer is essential to provide definitive treatment. Among many…
(more)
▼ Cancer has been one of main causes of human deaths for many years. Early detection of cancer is essential to provide definitive treatment. Among many cancer treatment methods, nanoparticle-mediated photothermal therapy is considered as one of the promising cancer treatment methods because of its non-invasiveness and cancer-specific therapy. Ultrasound and photoacoustic imaging can be utilized for both cancer detection and photothermal therapy guidance. Ultrasound elasticity imaging can detect cancer using tissue elastic properties. Once cancer is diagnosed, spectroscopic photoacoustic imaging can be used to monitor nanoparticle delivery before photothermal therapy. When nanoparticles are well accumulated at the tumor, ultrasound and photoacoustic-based thermal imaging can be utilized for estimating temperature distribution during photothermal therapy to guide therapeutic procedure.
In this dissertation, ultrasound beamforming, elasticity imaging, and spectroscopic photoacoustic imaging methods were developed to improve cancer detection and therapy guidance. Firstly, a display pixel based synthetic aperture focusing method was developed to fundamentally improve ultrasound image qualities. Secondly, an autocorrelation based sub-pixel displacement estimation method was developed to enhance signal-to-noise ratio of elasticity images. The developed elasticity imaging method was utilized to clinically evaluate the feasibility of using ultrasound elasticity imaging for prostate cancer detection. Lastly, a minimum mean square error based spectral separation method was developed to robustly utilize spectroscopic photoacoustic imaging. The developed spectroscopic photoacoustic imaging method was utilized to demonstrate ultrasound and photoacoustic image-guided photothermal cancer therapy using in-vivo tumor-bearing mouse models. The results of these studies suggest that ultrasound and photoacoustic imaging can assist both cancer detection and therapy guidance.
Advisors/Committee Members: Emelianov, Stanislav Y. (advisor), Aglyamov, Salavat R. (committee member), Sokolov, Konstantin V. (committee member), Hamilton, Mark F. (committee member), Pearce, John A. (committee member).
Subjects/Keywords: Ultrasound; Photoacoustic; Spectroscopic photoacoustic imaging; Elasticity imaging; Thermal imaging; Nanoparticle
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APA (6th Edition):
Kim, S. (2011). Ultrasound and photoacoustic imaging for cancer detection and therapy guidance. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-08-4024
Chicago Manual of Style (16th Edition):
Kim, Seungsoo. “Ultrasound and photoacoustic imaging for cancer detection and therapy guidance.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/ETD-UT-2011-08-4024.
MLA Handbook (7th Edition):
Kim, Seungsoo. “Ultrasound and photoacoustic imaging for cancer detection and therapy guidance.” 2011. Web. 23 Jan 2021.
Vancouver:
Kim S. Ultrasound and photoacoustic imaging for cancer detection and therapy guidance. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-4024.
Council of Science Editors:
Kim S. Ultrasound and photoacoustic imaging for cancer detection and therapy guidance. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-4024
University of Texas – Austin
22.
Cook, Jason Ray.
RF/microwave absorbing nanoparticles and hyperthermia.
Degree: MSin Engineering, Biomedical Engineering, 2009, University of Texas – Austin
URL: http://hdl.handle.net/2152/ETD-UT-2009-12-399
► The primary purpose of this work was to evaluate the capability of nanoparticles to transform electromagnetic energy at microwave frequencies into therapeutic heating. Targeted nanoparticles,…
(more)
▼ The primary purpose of this work was to evaluate the capability of nanoparticles to transform electromagnetic energy at microwave frequencies into therapeutic heating. Targeted nanoparticles, in conjunction with microwave irradiation, can increase the temperatures of the targeted area over the peripheral region. Therefore, to become clinically viable, microwave absorbing nanoparticles must first be identified, and a system to monitor the treatment must be developed.
In this study, ultrasound temperature imaging was used to monitor the temperature of deep lying structures. First, a material-dependent quantity to correlate the temperature induced changes in ultrasound images (i.e. apparent time shifts) to differential temperatures was gathered for a tissue-mimicking phantom, porcine longissimus dorsi muscle, and porcine fat. Then microwave nanoabsorbers were identified using an infrared radiometer. The determined nanoabsorbers were then injected into ex-vivo porcine longissimus dorsi muscle tissue. Ultrasound imaging frames were gathered during microwave treatment of the inoculated tissue. Finally, the ultrasound frames were analyzed using the correlation between temperature and apparent shifts in ultrasound for porcine muscle tissue. The outcome was depth-resolved temperature profiles of the ex-vivo porcine muscle during treatment.
The results of this study show that magnetite is a microwave nanoabsorber that increases the targeted temperature of microwave hyperthermia treatments. Overall, there is clinical potential to use microwave nanoabsorbers to increase the efficiency of microwave hyperthermia treatments.
Advisors/Committee Members: Emelianov, Stanislav Y. (advisor), Pearce, John A. (committee member).
Subjects/Keywords: Hyperthermia; Cancer; Ablation; RF; Radiofrequency; Microwave; Nanoparticle; Diathermy; Ultrasound Imaging; Thermoacoustic; Bioheat Transfer; Tissue Damage Models
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APA (6th Edition):
Cook, J. R. (2009). RF/microwave absorbing nanoparticles and hyperthermia. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2009-12-399
Chicago Manual of Style (16th Edition):
Cook, Jason Ray. “RF/microwave absorbing nanoparticles and hyperthermia.” 2009. Masters Thesis, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/ETD-UT-2009-12-399.
MLA Handbook (7th Edition):
Cook, Jason Ray. “RF/microwave absorbing nanoparticles and hyperthermia.” 2009. Web. 23 Jan 2021.
Vancouver:
Cook JR. RF/microwave absorbing nanoparticles and hyperthermia. [Internet] [Masters thesis]. University of Texas – Austin; 2009. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/ETD-UT-2009-12-399.
Council of Science Editors:
Cook JR. RF/microwave absorbing nanoparticles and hyperthermia. [Masters Thesis]. University of Texas – Austin; 2009. Available from: http://hdl.handle.net/2152/ETD-UT-2009-12-399
University of Texas – Austin
23.
Wei, Chia-ling.
Improvements in the accuracy of estimation of left ventricular volume from measurements of complex admittance using a tetrapolar catheter.
Degree: PhD, Electrical and Computer Engineering, 2004, University of Texas – Austin
URL: http://hdl.handle.net/2152/2177
► Cardiac volume has been estimated using conductance technology that generates an instantaneous volume-dependant conductance signal. Unfortunately, the measured conductance is a combination of blood and…
(more)
▼ Cardiac volume has been estimated using conductance technology that
generates an instantaneous volume-dependant conductance signal. Unfortunately,
the measured conductance is a combination of blood and myocardium, but only
the blood conductance is desired. Hence, the instantaneous parallel myocardial
contribution must be determined and removed from the total measured
conductance signal in order to accurately measure cardiac volume. The currently
adopted method assumes that the conductance-volume relationship is linear and
the myocardial contribution to the total measured conductance is constant during
a cardiac cycle. It also ignores either myocardial conductance or capacitance
when estimating the myocardial contribution. This dissertation deals with these
issues, and derives and validates a nonlinear conductance-to-volume conversion
equation. It also proves that myocardial contribution varies during the cardiac
cycle and develops a new method to calculate myocardial contribution using the
fact that myocardium is both conductive and capacitive.
Advisors/Committee Members: Pearce, John A., 1946- (advisor), Valvano, Jonathan W., 1953- (advisor).
Subjects/Keywords: Heart – Left ventricle; Myocardium; Catheters
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APA (6th Edition):
Wei, C. (2004). Improvements in the accuracy of estimation of left ventricular volume from measurements of complex admittance using a tetrapolar catheter. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/2177
Chicago Manual of Style (16th Edition):
Wei, Chia-ling. “Improvements in the accuracy of estimation of left ventricular volume from measurements of complex admittance using a tetrapolar catheter.” 2004. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/2177.
MLA Handbook (7th Edition):
Wei, Chia-ling. “Improvements in the accuracy of estimation of left ventricular volume from measurements of complex admittance using a tetrapolar catheter.” 2004. Web. 23 Jan 2021.
Vancouver:
Wei C. Improvements in the accuracy of estimation of left ventricular volume from measurements of complex admittance using a tetrapolar catheter. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2004. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/2177.
Council of Science Editors:
Wei C. Improvements in the accuracy of estimation of left ventricular volume from measurements of complex admittance using a tetrapolar catheter. [Doctoral Dissertation]. University of Texas – Austin; 2004. Available from: http://hdl.handle.net/2152/2177
University of Texas – Austin
24.
Porterfield, John Edward.
Admittance measurement for early detection of congestive heart failure.
Degree: PhD, Electrical and Computer Engineering, 2010, University of Texas – Austin
URL: http://hdl.handle.net/2152/ETD-UT-2010-05-858
► Impedance has been used as a tool for cardiac research since the early 1940’s. Recently there have been many advances in this field in the…
(more)
▼ Impedance has been used as a tool for cardiac research since the early 1940’s. Recently there have been many advances in this field in the diagnosis of human heart failure through the measurement of pacemaker and ICD coupled impedance detection to determine the state of pulmonary edema in patients through drops in lung impedance. These new detection methods are far downstream of the initial changes in physiology, which signify heart failure risk, namely, an increased left ventricular (LV) end-diastolic volume (also known as preload). This dissertation presents the first formal validation of the complex admittance technique for more accurate blood volume measurement in vivo in mice. It aims to determine a new configuration of admittance measurement in a large scale animal model (pigs). It also aims to prove that “piggybacking” an admittance measurement system onto previously implanted AICD and bi-ventricular pacemakers is a feasible and practical measurement that will serve as an early warning system for impending heart failure through the measurement of LV preload, which appears before the currently measured drop in lung impedance using previous techniques.
Advisors/Committee Members: Pearce, John A., 1946- (advisor), Valvano, Jonathan W. (committee member), Yilmaz, Ali (committee member), Rylander, Henry G. (committee member), Feldman, Marc D. (committee member).
Subjects/Keywords: Admittance; Heart failure; Diagnosis; Impedance; Blood volume; Biomedical engineering
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APA (6th Edition):
Porterfield, J. E. (2010). Admittance measurement for early detection of congestive heart failure. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2010-05-858
Chicago Manual of Style (16th Edition):
Porterfield, John Edward. “Admittance measurement for early detection of congestive heart failure.” 2010. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/ETD-UT-2010-05-858.
MLA Handbook (7th Edition):
Porterfield, John Edward. “Admittance measurement for early detection of congestive heart failure.” 2010. Web. 23 Jan 2021.
Vancouver:
Porterfield JE. Admittance measurement for early detection of congestive heart failure. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2010. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/ETD-UT-2010-05-858.
Council of Science Editors:
Porterfield JE. Admittance measurement for early detection of congestive heart failure. [Doctoral Dissertation]. University of Texas – Austin; 2010. Available from: http://hdl.handle.net/2152/ETD-UT-2010-05-858
University of Texas – Austin
25.
Starosta, Matthew Samuel, 1981-.
Three-dimensional computation of light scattering by multiple biological cells.
Degree: PhD, Electrical and Computer Engineering, 2010, University of Texas – Austin
URL: http://hdl.handle.net/2152/ETD-UT-2010-05-941
► This work presents an investigation into the optical scattering of heterogeneous cells with an application to two-photon imaging, optical scattering measurements and STED imaging. Using…
(more)
▼ This work presents an investigation into the optical scattering of heterogeneous cells with an application to two-photon imaging, optical scattering measurements and STED imaging. Using the finite difference time-domain (FDTD) method, the full-wave scattering by many cells containing multiple organelles with varying indices of refraction is computed. These simulations were previously limited to single cells for reasons of computational cost. A superposition approximation that uses the coherent linear superposition of FDTD-determined farfield scattering patterns of small numbers of cells to estimate the scattering from a larger tissue was developed and investigated. It was found that for the approximation to be accurate, the scattering sub-problems must at minimum extend along the incident field propagation axis for the full depth of the tissue, preserving the scattering that takes place in the direction of propagation. The FDTD method was used to
study the scattering effects of multiple inhomogeneous cells on the propagation of a focused Gaussian beam with an application to two-photon imaging. It was found that scattering is mostly responsible for the reduction in two-photon fluorescence signal as depth is increased. It was also determined that for the chosen beam parameters and the cell and organelle configurations used, the nuclei are the dominant scatterers. FDTD was also utilized in an investigation of cellular scattering effects on the propagation of a common depletion beam used in STED microscopy and how scattering impacts the image obtained with a STED microscope. An axial doughnut beam was formulated and implemented in FDTD simulations, along with a corresponding focused Gaussian beam to simulate a fluorescence excitation beam. It was determined that the depletion beam will maintain a well-defined axial null in spite of scattering, although scattering will reduce the resulting fluorescence signal with focal
depth.
Advisors/Committee Members: Pearce, John A., 1946- (advisor), Dunn, Andrew Kenneth, 1970- (advisor), Thomas, Robert J. (committee member), Milner, Thomas E. (committee member), Wilson, Preston S. (committee member), Ling, Hao (committee member).
Subjects/Keywords: Tissue optics; Optical propagation; Computational electromagnetics; Finite-difference time-domain
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APA (6th Edition):
Starosta, Matthew Samuel, 1. (2010). Three-dimensional computation of light scattering by multiple biological cells. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2010-05-941
Chicago Manual of Style (16th Edition):
Starosta, Matthew Samuel, 1981-. “Three-dimensional computation of light scattering by multiple biological cells.” 2010. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021.
http://hdl.handle.net/2152/ETD-UT-2010-05-941.
MLA Handbook (7th Edition):
Starosta, Matthew Samuel, 1981-. “Three-dimensional computation of light scattering by multiple biological cells.” 2010. Web. 23 Jan 2021.
Vancouver:
Starosta, Matthew Samuel 1. Three-dimensional computation of light scattering by multiple biological cells. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2010. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/2152/ETD-UT-2010-05-941.
Council of Science Editors:
Starosta, Matthew Samuel 1. Three-dimensional computation of light scattering by multiple biological cells. [Doctoral Dissertation]. University of Texas – Austin; 2010. Available from: http://hdl.handle.net/2152/ETD-UT-2010-05-941
. 
Open Access Theses and Dissertations
