We investigated an emerging brain-computer interface (BCI) modality, namely, transcranial Doppler ultrasonography (TCD), which measures cerebral blood flow velocity. We hypothesized that a bilateral TCD-driven online BCI would be able to dichotomously classify a user’s intentions with at least 70% accuracy. To test this hypothesis, we had three objectives: (1) to develop a signal classifier that yielded high (>80%) offline accuracies; (2) to develop an online TCD-BCI system with an onscreen keyboard; and, (3) to determine the achievable online accuracy with able-bodied participants. With a weighted, forward feature selection and a Naïve Bayes classifier, sensitivity and specificity of 81.44 ± 8.35% and 82.30 ± 7.39%, respectively, were achieved in the online differentiation of two mental tasks. The average information transfer rate and throughput of the system were 0.87 bits/min and 0.35 ± 0.18 characters/min, respectively. These promising online results encourage future testing of TCD-BCI systems with the target population.

<p>Prostate cancer (PCa) is the most common non-cutaneous cancer in men with an estimated almost 30,000 deaths occurring in the United States in 2014. Currently, the most widely utilized methods for screening men for prostate cancer include the digital rectal exam and prostate specific antigen analysis; however, these methods lack either high sensitivity or specificity, requiring needle biopsy to confirm the presence of cancer. The biopsies are conventionally performed with only B-mode ultrasound visualization of the organ and no targeting of specific regions of the prostate, although recently, multi-parametric magnetic resonance imaging has shown promise for targeting biopsies. Earlier work has demonstrated the feasibility of acoustic radiation force impulse (ARFI) imaging and shear wave elasticity imaging (SWEI) to visualize cancer in the prostate, however multiple challenges with both methods have been identified.</p><p>The aim of this thesis is to contribute to both the technical development and clinical applications of ARFI and SWEI imaging using the latest advancements in ultrasound imaging technology.</p><p>The introduction of the Siemens Acuson SC2000 provided multiple technological improvements over previous generations of ultrasound scanners, including: an improved power supply, arbitrary waveform generator, and additional parallel receive beamforming. In this thesis, these capabilities were utilized to improve both ARFI and SWEI imaging and reduce acoustic exposure and acquisition duration. However, the SC2000 did not originally have radiation force imaging capabilities; therefore, a new tool set for prototyping these sequences was developed along with rapid data processing and display code. These tools leveraged the increasing availability of general purpose computing on graphics processing units (GPUs) to significantly reduce the data processing time, facilitating real-time display for ultrasonic research systems.</p><p>These technical developments for both acquisition and processing were applied to investigate new methods for ARFI and SWEI imaging. Specifically, the power supply on the SC2000 allowed for a new type of multi-focal zone ARFI images to be acquired, which are shown to provide improved image quality over an extended depth of field. Additionally, a new algorithm for SWEI image processing was developed using an adaptive filter based on a maximum a posteriori estimator, demonstrating increases in the contrast to noise ratio of lesion targets upwards of 50%.</p><p>Finally, the optimized ARFI imaging methods were integrated with a transrectal ultrasound transducer to acquire volumetric in vivo data in patients undergoing robotic radical prostatectomy procedures in an ongoing study. When the study was initiated, it was recognized that the technological improvements of Siemens Acuson SC2000 allowed for the off-axis response to the radiation force excitation to be concurrently recorded without impacting ARFI image quality. This volumetric SWEI data was reconstructed retrospectively using the approaches developed in this thesis, but the images were low quality. A further investigation identified multiple challenges with the SWEI sequence, which should be addressed in future studies. The ARFI image volumes were very high quality and are currently being analyzed to assess the accuracy of ARFI to visualize prostate anatomy and clinically significant prostate cancer tumors. After a blinded evaluation of the ARFI image volumes for suspicion of prostate cancer, three readers correctly identified 63% of all clinically significant tumors and 74% of clinically significant tumors in the posterior region, showing great promise for using ARFI in the context of prostate cancer visualization for targeting biopsies, focal therapy, and watchful waiting.</p> / Dissertation

This research investigates the properties of flours of different wheat varieties, belonging to the Canadian Western Red Spring (CWRS) and Canadian Prairie Spring Red (CPSR) wheat classes, for their suitability in making yellow alkaline noodles (YAN), a staple of Asian diets. Maximum cutting stress (MCS), Stress-Relaxation and Kieffer rig tests are traditional methods that were used to evaluate cooked YAN firmness. Ultrasound at 50 kHz was used to measure the rheological properties of raw YAN made from the various wheat classes/varieties. In general, higher protein CWRS wheat class flours produced firmer YAN, but some CPSR wheat varieties produced comparable if not firmer YAN despite being significantly lower in flour protein content. These differences were also evident from ultrasonic tests. My research demonstrates the suitability of Canadian wheat for YAN production as well as ultrasound’s ability to discriminate raw YAN rheological properties.

Tiriamajame darbe nagrinėjamas ultragarso pritaikymas ultragarsinei levitacijai ore sukelti. Nagrinėjama ultragarsinės levitacijos taikymas medicinoje ir įvairių gabaritų įrenginiuose , taip pat didelių pramoninių agregatų veikime. Apžvelgiant tokių sistemų konstrukciją, galima rasti įvairių trūkumų, kuriuos ateityje galima tobulinti. Vienas iš didžiausių pastebėtų trūkumų - tai sistemos gabaritiniai matmenys. Todėl baigiamojo darbo metu buvo ieškota įvairių sprendimų kaip šį trūkumą išspręsti, ir buvo iškelti tikslai : 1. Optimizuoti Laboratorijoje turimą išilginių – lenkimo ultragarsinių virpesių T – tipo sistemą. 2. Sukurti ir ištirti naują radialinę lenkimo virpesių sistemą. Darbo uždaviniai : Išanalizuoti galingos ultragarsinių virpesių stovinčios bangos dideliame plote sukėlimo ypatybes. Susipažinti su Laboratorijoje esama T- tipo sistema, išanalizuoti jos darbą. Atlikti ultragarsinių sistemų kompiuterinį modeliavimą . Optimizuoti diskinio rezonatoriaus lenkimo virpesių rezonatoriaus skerspjūvį. Suprojektuoti, pagaminti ir suderinti optimizuotas sistemas. Iš elektrinės ir mechaninės pusės ištirti ultragarsines sistemas: nustatyti impedanso – dažninę ir fazinę bei amplitudines – dažnines charakteristikas prie įvairių elektrinių galių. Nustatyti levitacijos keliamos jėgos priklausomybę nuo paduodamos į pjezokeitiklį galios. Tiriamojo darbo metu nagrinėjamos jau sukurtos ir laboratorijoje... [toliau žr. visą tekstą] / The research is focused on the adaptation of ultrasound for creating airborne ultrasonic levitation. The study investigates the application of ultrasonic levitation for medical purposes and in the equipment of different dimensions, also in the operation of large industrial units. A closer look at the structure of such systems allows to detect multiple defects that could be eliminated in the future. One of the most evident defects is the size of the system. Thus, the purpose of this paper is the search of various solutions with the following objectives set forth: 1. Optimisation of longitudinal-bending ultrasonic vibration T type system used in the lab. 2. Creation and investigation of a new radial bending vibration system. Tasks of the study: To analyse the specifics of generating a powerful ultrasonic vibration standing wave in a big area. To get acquainted with T type system used in the lab, to analyse the operation of the system. To perform computer modeling of ultrasonic systems. Optimise the cross-section of disc type bending-mode resonator. To plan, build and fine-tune the optimised systems. To perform electrical and mechanical investigation of ultrasonic systems: to set frequency/phase and amplitude/frequency characteristics of impedance at different electrical voltages. To set the dependance of levitation power on the piezo converter input voltage. The study contains the analysis of the already created and used in the lab T type systems, their characteristics and... [to full text]

It is well known that liquid coupling agents, which are commonly used in conventional ultrasonic testing to couple an ultrasonic transducer to a solid specimen, cause a number of problems including inconsistency in results and slowness of the inspection. This is especially true when the specimen surface is rough, such as those in field concrete structures; here the solution involves time-consuming surface preparation to polish every single point of inspection, making it impractical to inspect field structures with conventional, contact methods. To address this issue, this thesis proposes a new, fully non-contact, air-coupled measurement setup in the mid to high ultrasonic frequencies (50-150 kHz). This advanced setup and measurement technique is evaluated by calculating the signal to noise ratio for different numbers of signal averages. In addition, the effect of the lift-off distance of the transducer over the sample is also investigated. Ultrasonic waves are generated and detected in this frequency range with a sufficiently high signal to noise ratio (SNR), which enables performing a fast scan with a small number of signal averages. Using this setup, phase velocity and attenuation of Rayleigh surface waves in a concrete specimen are first measured. Then, the air coupled ultrasound technique is used to detect dicontinuities such as cracks at a concrete joint and reinforcement bars in a concrete block. Also, the capability of the proposed technique for measuring depths of surface-breaking cracks using air-coupled generated Rayleigh waves is demonstrated. Since this measurement setup directly generates Rayleigh waves, most of the disadvantages in the techniques based on the impact-echo method can be avoided and thus data processing is much simpler than that in the impact-echo based techniques. The results of the measurements show that this setup is highly promising and a big advancement towards the rapid ultrasonic nondestructive testing on large-scale field concrete structures.

This thesis is based on observations of the physical properties of wheat flour dough using ultrasonic measurements. Three frequency ranges were used in the study, low frequencies (near 40 kHz), intermediate frequencies (1 to 5 MHz, where bubble resonance effects are apparent), and high frequencies (near 20 MHz). Doughs mixed under different head space air pressures, from vacuum to atmospheric pressure, as well as under nitrogen, were studied at low frequency to investigate their relaxation behavior. Subsamples from ambient dough and vacuum dough displayed differences in the dependence of velocity and attenuation on time after compression, but no post mixing relaxation effect was apparent. A critical headspace pressure of approximately 0.16 atmospheres determined whether vacuum-like or ambient-like relaxation was observed. A peak in attenuation and changes in ultrasonic velocity were observed around the bubble resonance frequency, and these ultrasonic parameters changed substantially as a function of time. A bubble resonance model was used to interpret the results around the bubble resonance frequency, and bubble size distributions were estimated for ambient and vacuum dough from the ultrasonic data. For the high frequency range, a molecular relaxation model was used to interpret the results. Different fast relaxation times were observed for ambient dough (5 ns) and vacuum dough (1 ns). This relaxation time may be associated with conformational rearrangements in glutenin inside the dough matrix. These experiments have enabled dough relaxation to be probed over a very wide range of time scales (from ns to hours), and will lead to a better understanding of the role of dough matrix and gas cell effects on the physical properties of wheat flour doughs.

Crude gliadins were extracted from Canada Western Red Spring (CWRS) wheat flour with 70% (v/v) aqueous ethanol solutions and then lyophilized. Lyophilized crude gliadins were dissolved in 70% (v/v) aqueous ethanol (EtOH) or 4 mM acetic acid (HAc) and the density and ultrasound properties were measured at 20 °C. Good linear relationships of density, ultrasound velocity and ultrasound attenuation with solution concentrations were found. Solvent and sonication effects on the crude gliadins were discussed in terms of the values of the partial specific volume and the partial specific adiabatic compressibility coefficient for crude gliadins. The ethanol soluble crude gliadins had a larger partial specific volume and larger partial specific adiabatic compressibility coefficient than those for acidic soluble crude gliadins. These large values for the physical properties of ethanol soluble crude gliadins were thought to be evidence for the existence of complexes formed by some proteins (ethanol soluble LMW-glutenins and gliadins) and lipids in ethanol solutions and it was also found that the protein-lipid complexes were not destroyed by sonication treatment. Besides, there was no evidence showing that gliadins change with different wheat flours and cause different volume and compressibility properties of crude gliadins.

The production of highly aerated foods remains a challenge that requires skill to obtain desired appearance and texture. Since foams are fragile and inherently unstable, evaluation of structure changes with time requires a delicate approach. Non-invasive but informative evaluation of changes in aerated food properties is a desired goal to be achieved in this thesis. I studied the aging of egg white foams of different void fraction using two noninvasive techniques - ultrasonic spectroscopy and electrical resistivity - with a view to understanding aging mechanisms that would affect the quality of the final product. To help in interpretation of the results, a commercial high void fraction foam, Gillette (Sensitive), was also analyzed. As a support technique for ultrasound results I used image analysis in order quantitatively evaluate the size of bubbles in the foams. Large increases in attenuation were observed with increasing aging time and frequency. Results were modeled using an effective medium theory originated by Foldy (1945) in order to understand the factors governing foam lifetime and texture. From electrical resistance measurements, liquid fraction changes in an egg white foam column were evaluated quantitatively and qualitatively by using a generalized free drainage model. Although egg-white foams were more prone to changes due to drainage, I observed that for all foams the ultrasonic scaling parameter alfa*lambda/freq was proportional to the square of average bubble size (indicative of a diffusively driven aging process due to disproportionation of bubbles). Slopes of alfa*lambda/freq versus aging time were 6*10-8 and 11*10-8 for egg white foams of void fraction 0.65 and 0.78, respectively, indicating that disproportionation progressed approximately twice as fast in the high void fraction foam. The slopes of alfa*lambda/freq versus aging time were similar for both Gillette foam void fractions (0.93 and 0.91) at a value of 1.5*10–8 s-1, attributable to a lower solubility of isobutane compared to air. By combining ultrasound and electrical resistivity, this thesis has provided novel insights into understanding instability processes occurring in foams. Potentially, ultrasound techniques could be used instead of imaging for foam aging studies, since non-invasive and non-destructive measurements of attenuation and phase velocity permit interrogation of opaque foam structures.

The addition of pea fibre to wheat bread supports the growing trend of improving health through diet. Various evaluation tools (bread scoring, C-cell, texture profile analysis, and ultrasound) were used to monitor the sensory and mechanical quality of air bubbles in bread. Different pea fibre particle sizes (250, 125, 180, 90 μm) were added at 0, 2, 4, 6, 8 g/serving into a bread formulation. Improvements in specific loaf volume were observed when water absorption was optimized. Adequate water absorption mitigated the high dough viscosity effect of pea fibre. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay was used to measure antioxidant activity of pea fibre. All particle sizes of pea fibres had substantially greater antioxidant scavenging ability compared to wheat flour. The DPPH scavenging activity of pea fibre approached that of ascorbic acid by the end of the assay. Fibre-enriched bread had higher antioxidant activity compared to that of the control bread.

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