249 research outputs found
Frequency Response of the Swim Bladder and Weberian Ossicles of Zebrafish (Danio Rerio)
No full textIn recent years, the use of zebrafish as human disease models has been expanded to include several forms of human deafness. Zebrafish provide convenient hosts for genetic and developmental investigation. However, knowledge of the physical mechanism of zebrafish ���hearing��� is limited compared to other current models and human physiology. Examining the frequency response of the swim bladder and Weberian ossicles would allow the development of a mechanical understanding of the ear and comparison to the human middle ear. The swim bladder and Weberian ossicles are believed to transmit sound stimuli and give zebrafish the ability to determine an extended frequency range, as ���hearing specialists,��� among fish species. In order to understand the ability of the structures to function as a sound transducer, the frequency response of the structures was measured through phase-sensitive OCT. The anterior swim bladder and Weberian ossicles were visualized via magnitude OCT and data collected along a line through the surface and ROIs. The displacement of the structures in the presence of a sound stimulus suggested coupling of the acoustic energy through the tissue to the anterior swim bladder and to the fourth Weberian ossicle. A tuning response on the anterior swim bladder revealed an increase in vibration magnitude with decreasing frequency stimuli and increasing sound intensity. Danio rerio hears over a range of 100-4000 kHz. However owing to limitations in the current experimental system, we were only able to investigate in the range of 2500-4000 kHz
Application of Multi-Tonal Complex with Optical Coherence Tomography Imaging System for Vibrometric Analysis of Inner-Ear Structures
No full textCurrently, research is being conducted on single tone sound transduction within the auditory portion of the inner ear, the cochlea [1]. The study of cochlear mechanics in large rodents has provided important insight into cochlear function [1]. Additionally, multi-tone stimuli can provide a new perspective in vibrometric analyses that could be used in audiometry as a measure of hearing loss for patients in terms of both magnitude and their unique frequency envelope. Therefore, the proposed study was aimed to test the recent implementation of multitone calibration into an existing python program, PyVib2, which was used during Optical Coherence Tomography (OCT) imaging experiments for vibrometric analysis of the structures in the inner-ear. Within PyVib2, the multi-tone stimulus program will be executed in conjunction with the OCT M-scan program for full vibrometric analysis. This research resulted in the further development of the PyVib2 program, the acquisition of insightful image data of structures of the human inner-ear, which was collected using the OCT imaging system, and the verification of extracting the vibratory response of these structures when subjected to a multi-tone stimuli
A Recording Project Featuring Five Newly Commissioned Works for Clarinet by James Patrick Applegate
No full textabstract: ABSTRACT
This project features five new pieces for clarinet commissioned from three different composers including:
1. Rasa by Jeffrey Ouper
2. Faerie Tale Dances by Jeffrey Ouper
3. Amalgamated Widget by Tavia Sullens
4. Faerie Suite by Theresa Martin
5. Time Lapse by Theresa Martin
Faerie Suite and Amalgamated Widget are for unaccompanied clarinet; Time Lapse is a trio for clarinet, bass clarinet, and piano; Faerie Tale Dances is a trio for E-flat clarinet, sopranino recorder, and toy piano; and Rasa is a quartet for E-flat clarinet, two A clarinets, and bass clarinet. These pieces challenge the performer in various ways, including complex rhythm, use of extended techniques such as glissando, flutter tongue, and circular breathing, and synthetic and non-traditional scales. The composers were given guidelines prior to the compositional process to create works with a thematic connection to mythology, folklore, or fairy tales, and inspired by dance and non-western or traditional harmonies and idioms. This document offers background information about the composers and the works, and a performance guide is included for each. This guide provides recommendations and suggestions for each piece. Also included are interviews with each of the composers. Accompanying this document are recordings of each of the five pieces, performed by the author.Dissertation/ThesisRasa AudioAmalgamated Widget AudioFaerie Tale Dances- I. The Stroke of Midnight AudioFaerie Tale Dances- II. Mirror, Mirror AudioFaerie Tale Dances- III. Pixie Dust AudioFaerie Suite- I. Titania AudioFaerie Suite- II. Eurydice AudioFaerie Suite- III. LoreleiFaeie Suite- IV. Lugh's DanceTime LapseDoctoral Dissertation Music 201
Barium Titanate Nanoparticles as Exogenous Contrast Agents in Second Harmonic Optical Coherence Tomography
No full textI propose and demonstrate a method by which barium titanate nanoparticle clusters can be used as exogenous contrast agents in Second Harmonic Optical Coherence Tomography imaging systems to localize and highlight desired regions of tissue. SH-OCT has previously been used to identify collagen within OCT images. However, SH-OCT signals from collagen are highly susceptible to inferior reflector artifacts because most of the second harmonic generated light is forward scattered. Second harmonic generating nanoparticle clusters exhibit high scattering properties, which can give them the advantage of backscattering a large quantity of second harmonic light while attenuating the forward scattered light. In this research project, a mathematical model is proposed in which the backward to forward scattering ratio of second harmonic generated light from nanoparticle layers is exponentially proportional to the thickness of the layer. This model was supported by measurements of the backward to forward scattering ratio of second harmonic light in barium titanate nanoparticles layers. This indicates that nanoparticle clusters can be designed and manufactured with the proper thickness so that they generate a large second harmonic signal without creating inferior reflector artifacts
Integrating OCT into Surgical Systems and Monitoring Vibrations
No full textImaging of the hearing structures can yield information regarding their function as well as insight into the abnormalities and adverse conditions that affect them. Improvements in the acquisition techniques and the quality of imaging systems can contribute to the understanding and treatment of these conditions. Optical coherence tomography (OCT) imaging technology has evolved to the point where systems can deliver 2D cross-sectional images, 3D structural volumes, and functional information regarding the motion of the sample. The information is valuable, but while research systems continue to evolve and become more advanced there is a disconnect between the researcher and the clinician. Translation of research based imaging systems into the clinical field is an important step in future development and adaptation. This thesis is focused on the development of a packaged optical coherence tomography system and the design of a phase-stable surgical microscope OCT system that can easily be introduced into the clinical field
JAHN-TELLER ANALYSIS OF THE VIBRONIC STRUCTURE OF THE STATE IN THE CYCLOPENTADIENYL RADICAL
No full textNelson H. H.: Pasternack L.: Mc Donald J.R. Chem. Phys. 1983, 74, 227. Applegate B.E.: Barekholtz T. A.: Miller T.A. to be publishedAuthor Institution: Dept. of Chemistry Laser Spectroscopy Facility, The Ohio State University; Dept. of Chemistry Laser Spectroscopy Facility, The Ohio State University, Dept. of Chemistry, Laser Spectroscopy Facility, 120 W. 18th Avenue, Columbus, Ohio 43210;; JILA, National Institute of Standards and Technology and The Department of Chemistry and Biochemistry, University of Colorado BoulderWhile room temperature wavelength resolved emission spectra of the transition have existed for nearly 20 , the vibrational assignment of these spectra has remained elusive. The major difficulty with the vibrational analysis is attributable to complications arising from the dynamic Jahn-Teller effect in the state. Newly obtained jet-cooled laser excited wavelength resolved fluorescence emmision spectra, in conjunction with calculations aimed at predicting the relevant Jahn-Teller constants have now made the complete analysis of the available spectral data possible. The transitions involving the Jahn-Teller active vibrations have been analyzed in terms of the three lowest energy harmonic vibrations of the appropriate symmetry(), assuming only linear Jahn-Teller interactions. Additional features of the spectrum may be described in terms of the fundamentals, overtones, and combination bands of the non-John-Teller active vibrations as well as combinations involving the Jahn-Teller active modes
Investigation of Nanoparticles for Use in Microwave Systems in Biomedicine
No full textThis research focuses on the microwave properties of nanoparticles for use as contrast and hyperthermia agents. Currently, visible light is used for irradiation of nanoparticles as hyperthermia agents. Additionally, visible/Near-infrared light is used for photoacoustic tomography (PAT) imaging. Compared to optical wavelengths, frequencies in microwave range transmit through tissue with high penetration depth . Thus, deep cancerous cells and malignant tissue may be treated and imaged. These nanoparticles could enable the use of a hybrid microwave/acoustic technique known as thermoacoustic tomography.
Here, quantitative measurements of the heat generation in super paramagnetic iron oxide nanoparticle (SPIONs), gold nanoparticles (AuNPs), and gold nanoclusters (AuNCs) induced by microwave energy at 3 GHz, are presented and compared. Based on our experiments, SPIONs are the most efficient nanoparticles for microwave heating. Very high concentrations of SPIONs are able to convert microwave energy into heat about 22�� C more than DI-water. AuNPs, which support plasmon resonances, do not provide heat under microwave irradiation as predicted by our computational analysis based on Mie Theory. AuNCs are a new form of ultra-small (<2.5 nm) AuNPs which do not support plasmonic resonances and have supra-molecular properties such as sub-conduction band transitions. Interestingly, AuNCs have the potential to absorb microwave energy and may provide an alternative to SPIONs. These nanoparticles had not yet been studied before in this frequency region. In addition, the absorption coefficient of nanoparticles were calculated using complex permittivity data from a dip probe kit and a Vector Network Analyzer (VNA) in a broad band range from 500 MHZ to 10 GHz. This method allows identification of best frequency region with highest penetration depth. In the last step, the nanoparticles with different concentrations were tested as exogenous contrast agents in a Thermoacoustic Tomography (TAT) system. TAT utilizes the penetration depth of microwave energy while producing high resolution images through acoustic waves. The addition of an exogenous contrast agent improves image quality by more effectively converting microwave energy to heat. The experiment reveals that the time resolved thermoacoustic signal (TA) from SPIONs is stronger than AuNPs and AuNCs and thus, the image contrast produced by SPIONs is stronger than the two other aforementioned nanoparticles
VIBRONIC SFECTROSCOPY OF TRANSITION
No full textR. Rubino, J. Williamson, and T. A. Miller, J. Chem. Phys. 103 (14 (1995)Author Institution: Laser Spectroscopy Facility, Department of Chemistry, The Ohio State UniversityWe report the laser excitation and dispensed fluorescence spectra of the transition. Improvements to the experiment have allowed the observation of important vibronic features not previously observed. The radical was produced in a free jet expansion from the simultaneous photolysis of and the laser vaporization of solid Mg. The use of as a precursor substancially improves production of the radical. A resolution laser was used to obtain the partially rotationally resolved LIF spectra of the , and transitions. Analysis of these spectra, along with the previously band yield structural parameters which provide information about the radical’s state. Besides the usual rotational constants, we have obtained information about the Jahn-Teller effect, which is dynamic and relatively weak. We have also obtained the values of the Coriolis coupling and the spin-orbit coupling constants. The fluorescence lifetime was found to be 60(7) ns for the vibrationless level of the state and less than 15 ns for transitions involving vibrational excitation. The dispersed fluorescence spectra of the jet-cooled was analyzed, and all observed state vibrational features were assigned
Design and Optimize a Two Color Fourier Domain Pump Probe Optical Coherence Tomography System
No full textMolecular imaging using fluorescence spectroscopy-based techniques is
generally inefficient due to the low quantum yield of most naturally occurring
biomolecules. Current fluorescence imaging techniques tag these biomolecules
chemically or through genetic manipulation, increasing the complexity of the system. A
technique capable of imaging these biomolecules without modifying the chromophore
and/or its environment could provide vital biometric parameters and unique insights into
various biological processes at a molecular level.
Pump probe spectroscopy has been used extensively to study the molecular
properties of poorly fluorescing biomolecules, because it utilizes the known absorption
spectrum of these chromophores. Optical Coherence Tomography (OCT) is an optical
imaging modality that harnesses the power of low coherence interferometry to measure
the 3-D spatially resolved reflectivity of a tissue sample. We plan to develop a new
molecular imaging modality that combines these techniques to provide 3-D, highresolution
molecular images of various important biomolecules. The system uses a Fourier domain OCT setup with a modified sample arm that
combines the "pump" and "probe" beams. The pump beam drives the molecules from
the ground state to excited state and the probe interrogates the population change due to
the pump and is detected interferometrically. The pump and the probe beam
wavelengths are optimized to maximize absorption at the pump wavelength and
maximize the penetration depth at the probe wavelength. The pump-probe delay can be
varied to measure the rate at which the excited state repopulates the ground state, i.e., the
ground state recovery time. The ground state recovery time varies for different
chromophores and can potentially be used to identify different biomolecules.
The system was designed and optimized to increase the SNR of the PPOCT
signals. It was tested by imaging hemoglobin and melanin samples and yielded
encouraging results. Potential applications of imaging hemoglobin using this technique
include the mapping of tissue microvasculature and measuring blood-oxygen saturation
levels. These applications could be used to identify hypoxic areas in tissue. Melanin
imaging can provide means of demarcation of melanoma in various organs such as skin,
eye and intestines
Modeling Aspects and Computational Methods for Some Recent Problems of Tomographic Imaging
No full textIn this dissertation, two recent problems from tomographic imaging are studied, and results from numerical simulations with synthetic data are presented.
The first part deals with ultrasound modulated optical tomography, a method for imaging interior optical properties of partially translucent media that combines optical contrast with ultrasound resolution. The primary application is the optical imaging of soft tissue, for which scattering and absorption rates contain important functional and structural information about the physiological state of tissue cells. We developed a mathematical model based on the diffusion approximation for photon propagation in highly scattering media. Simple reconstruction schemes for recovering optical absorption rates from boundary measurements with focused ultrasound are presented. We show numerical reconstructions from synthetic data generated for mathematical absorption phantoms. The results indicate that high resolution imaging with quantitatively correct values of absorption is possible. Synthetic focusing techniques are suggested that allow reconstruction from measurements with certain types of non-focused ultrasound signals. A preliminary stability analysis for a linearized model is given that provides an initial explanation for the observed stability of reconstruction.
In the second part, backprojection schemes are proposed for the detection of small amounts of highly enriched nuclear material inside 3D volumes. These schemes rely on the geometrically singular structure that small radioactive sources represent, compared to natural background radiation. The details of the detection problem are explained, and two types of measurements, collimated and Compton-type measurements, are discussed. Computationally, we implemented backprojection by counting the number of particle trajectories intersecting each voxel of a regular rectangular grid covering the domain of detection. For collimated measurements, we derived confidence estimates indicating when voxel trajectory counts are deviating significantly from what is expected from background radiation. Monte Carlo simulations of random background radiation confirm the estimated confidence values. Numerical results for backprojection applied to synthetic measurements are shown that indicate that small sources can be detected for signal-to-noise ratios as low as 0.1%
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