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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
321

Multiphase assessment of respiratory function

Fry, Michael W. 16 September 2015 (has links)
<p> The emergence of more sophisticated full body plethysmograph systems has occurred over recent years and called for broader testing of respiratory functions. Specific airway resistance and intrathoracic gas volume or functional residual capacity can provide more accurate measure of lung function utilizing a computerized full body plethysmograph. Clinics or specialized test facilities today could use this type of system for testing, evaluation, and long term monitoring of patients suspected of suffering from pulmonary disease of which there is no cure. A virtual machine was used for pulmonary function test and serialized collaboration of data was demonstrated to offer more access to diagnosis and treatment of respiratory diseases. Another non-invasive method of respiratory function can be indirectly measured from electrocardiogram. In addition patient respiratory rate is routinely measured using acoustic method. This multiphase evaluation of respiratory function examined cloud services, virtual machines, spirometry, plethysmography, indirect, and acoustic assessment of pulmonary function.</p>
322

FEEDBACK SYSTEMS FOR IMAGE ACQUISITION AND PROCESSING

Tamura, Nobuhiko January 1979 (has links)
No description available.
323

Localized fast field-cycling NMR relaxometry

Pine, Kerrin J. January 2014 (has links)
Conventional MRI relies on a strong fixed magnetic field B0 which is stable during the imaging process. By contrast, field-cycling MRI switches the strength of B0 up or down during an experiment. In this way, field-cycling provides access to endogenous information not accessible to standard MRI, such as enhanced T1 relaxation at certain NMR frequencies due to interactions between hydrogen and nitrogen nuclei in proteins. However, biomedical research of T1 dispersion is limited by the unavailability of equipment and rapid software methods. Strategies are presented to address these deficiencies. A removable electromagnet was designed and implemented for use with a 59-mT vertical-field, permanent-magnet based imager. The resistive magnet locally offsets the primary field over a small projected region to enable field-cycling relaxometry on an otherwise-conventional imager. Radiofrequency coils were constructed to suit the electromagnet’s configuration. T1 dispersion measurements were demonstrated for, separately, the finger joints and forearm of a human volunteer. Prior to this work, producing graphs of T1 dispersion from a volume of interest required lengthy T1 mapping at each field strength step. A new pulse sequence combining SR/IR T1 determination with field-cycling and point-resolved spectroscopy localization enables the measurement of dispersion curves of a volume selected from a pilot image. Its advantages include less partial voluming than whole-sample relaxometry, as well as better SNR and faster acquisition times than image-based techniques. The sequence’s sensitivity is sufficient to reveal distinctive ‘quadrupole dips’ in dispersion curves. To the author’s knowledge, it is the first pulse sequence to enable the relationship between T1 and field strength to be examined in times which are feasible for clinical investigations. Used together as presented in this thesis, the hardware and software developed represent a step towards field-cycling being used to reveal useful diagnostic information inaccessible to conventional MRI.
324

Anticipatory Coarticulation and Stability of Speech in Typically Fluent Speakers and People Who Stutter Across the Lifespan| An Ultrasound Study

Belmont, Alissa J. 07 August 2015 (has links)
<p> This study uses ultrasound to image onset velar stop consonant articulation in words. By examining tongue body placement, the extent of velar closure variation across vowel contexts provides for the measurement of anticipatory coarticulation while productions within the same vowel context provide measurement of extent of token-to-token variation. Articulate Assistant Advanced 2.0 software was used to semi-automatically generate midsagittal tongue contours at the initial point of maximum velar closure and was used to fit each contour to a curved spline. Patterns of lingual coarticulation and measures of speech motor stability, based on curve-to-curve distance (Zharkova, Hewlett, &amp; Hardcastle, 2011), are investigated to compare the speech of typically fluent speakers to the speech of people who stutter. Anticipatory coarticulation can be interpreted as a quantitative measure indicating the maturity of the speech motor system and its planning abilities. Token-to-token variability is examined from multiple velar vowel productions within the same vowel context, describing the accuracy of control, or stability, of velar closure gestures. Measures for both speaking groups are examined across the lifespan at stages during speech development, maturation, and aging. Results indicate an overall age effect, interpreted as refinement, with increased speech stability and progressively more segmental (less coarticulated) productions across the lifespan. A tendency toward decreased stability and more coarticulated speech was found for younger people who stutter, but this difference was small and absent among older adults. Outcomes of this study suggest the articulatory maturation trajectories of people who stutter may be delayed, but overall maturation of the speech mechanism is evident by older adulthood for typically fluent speakers and those who stutter. Applications to intervention are discussed in closing. </p>
325

Mobile magnetic resonance imaging system and its application

揚思敏, Yeung, Sze-man. January 2001 (has links)
published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy
326

Diffusion tensor imaging application

Shen, Litao 03 November 2015 (has links)
<p> Central nervous system (CNS) related conditions and diseases like mild traumatic brain injury (mTBI) and multiple sclerosis (MS) affect people&rsquo;s life quality, yet there is no single test for the diagnosis of these diseases or conditions. Patients may need to wait for years until they are diagnosed correctly to get the correct treatment, which is often too late. Thus, there is a strong need to develop some techniques to aid the diagnosis of CNS-related conditions and diseases. The conventional MRI can reveal the structure of the brain but cannot detect the difference between the healthy tissue and the anomalies. Diffusion tensor imaging (DTI) has been used for detecting white matter integrity and demyelination for the past decade in experiments and has been proven to have the ability to depict the problem effectively. In the past decade, many techniques were found based on DTI data, and these techniques improved pre-processing, processing, and post-processing. </p><p> Though there are many software and APIs that can provide functions for DTI file input/output (IO), visualization and other DTI related topics, there is no general software or API that is dedicated to covering the whole processing procedure of DTI that at the same time can be extended easily by the user. This thesis is dedicated to developing a software that can be used to aid in the diagnosis of CNS-related conditions and diseases while at the same time trying to cover as many topics as possible. Another purpose is to make the software highly extensible. </p><p> This thesis work first introduces the background of CNS-related disease and uses MS as an example to introduce the process of demyelination and the white matter integrity problem, which are involved in these CNS-related diseases and conditions. Then the diffusion process and the technique that can detect the diffusion signal (DTI) is presented. After this, concepts and meaning of the secondary metrics are discussed. Then, current existing software and APIs and their advantages and disadvantages are outlined. After these points, the techniques that are discussed in this thesis as well as their advantages are outlined. This part is followed by the charts and code samples which can illustrate the process and structure of this software. Then different modules and their results are explained. </p><p> In this software, the results are represented by images and 3D models. There are color images, pseudo color images with different schemes and gray scale images. Images are mainly included to represent the FA and MD data. In this software, streamlines are generated from the eigenvalue and eigenvector. Then a bundled result for the streamline is also realized in this software. The streamline and bundled results are 3D models. For 3D models, there are mainly two ways to display the real 3D model. One is the naked eye 3D which doesn&rsquo;t require the user to wear glasses but has less stereoscopic characteristics. As the stereoscopic monitors and glasses are more and more popular and easily accessible, this software also provides stereoscopic views for 3D models, and the user can choose red &amp; blue, interlaced techniques with proper glasses. </p><p> This thesis work ends with the discussion of the results and limitations of DTI. Finally, there is a discussion about the future work that can improve the performance of this software and topics that need to be covered.</p>
327

THE THEORY OF IMAGE SAMPLING AND MULTIPLEXING USING PHASE GRATINGS

Shrode, Theodore Edward, 1942- January 1976 (has links)
No description available.
328

Characterization of Combat-Induced PTSD in OEF/OIF Veterans Using MEG-Based Imaging

Rutledge, Omar 17 October 2015 (has links)
<p> <i>Background:</i> Post-traumatic stress disorder (PTSD) is a mental health disorder characterized by symptoms such as insomnia, irritability, issues with memory, difficulty concentrating, and poor decision-making abilities. With symptoms that closely resemble those of other anxiety disorders, it is very difficult to accurately diagnose. More research is needed to identify structural and functional imaging biomarkers to aid in diagnosis.</p><p> <i>Methods:</i> Ten right-handed male subjects (5 combat-exposed veterans, 5 healthy civilian controls) underwent magnetoencephalographic recording for this study. MEG data were acquired with a 275-channel whole-head CTF Omega 2000 system. Resting-state and tasked-based (Stroop Color-Naming Task) data were acquired. Voxel-based time-frequency analysis was subsequently performed using NUTMEG and SPM8.</p><p> <i>Results:</i> Significant differences were found between the two groups at rest (in delta, theta, gamma, and high-gamma neural oscillatory frequency bands) and during the Stroop Color-Naming task (in alpha, beta, and gamma, and high-gamma frequency bands).</p><p> <i>Conclusions:</i> Despite the small sample size, we were able to replicate some aspects of previous MEG research in veterans with PTSD. Not only does this result substantiate the use of MEG for population studies, but it also shows that PTSD is a mental disorder that is physical in nature and can be characterized through passively observing electromagnetic neuronal activity.</p>
329

Thermal monitoring of active volcanoes using portable infrared imagers

Spampinato, Letizia January 2011 (has links)
No description available.
330

Lucky imaging : beyond binary stars

Staley, Timothy January 2013 (has links)
No description available.

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