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Tree series transformations computed by bottom-up and top-down tree series transducers are called bottom-up and top-down tree series transformations, respectively. (Functional) compositions of such transformations are investigated. It turns out that the class of bottomup tree series transformations over a commutative and complete semiring is closed under left-composition with linear bottom-up tree series transformations and right-composition with boolean deterministic bottom-up tree series transformations. Moreover, it is shown that the class of top-down tree series transformations over a commutative and complete semiring is closed under right-composition with linear, nondeleting top-down tree series transformations. Finally, the composition of a boolean, deterministic, total top-down tree series transformation with a linear top-down tree series transformation is shown to be a top-down tree series transformation.

The goal of this research was to develop acoustic sensors and actuators for microfluidic applications. To this end, capacitive micromachined ultrasonic transducers (cMUTs) were developed which generate guided acoustic waves in fluid half-spaces and microchannels. An interdigital transducer structure and a phased excitation scheme were used to selectively excite guided acoustic modes which propagate in a single lateral direction. Analytical models were developed to predict the geometric dispersion of the acoustic modes and to determine the sensitivity of the modes to changes in material and geometric parameters. Coupled field finite element models were also developed to predict the effect of membrane spacing and phasing on mode generation and directionality. After designing the transducers, a surface micromachining process was developed which has a low processing temperature of 250C and has the potential for monolithically integrating cMUTs with CMOS electronics. The fabrication process makes extensive use of PECVD silicon nitride depositions for membrane formation and sealing. The fabricated interdigital cMUTs were placed in microfluidic channels and demonstrated to sense changes in fluid sound speed and flow rate using Scholte waves and other guided acoustic modes. The minimum detectable change in sound speed was 0.25m/s, and the minimum detectable change in flow rate was 1mL/min. The unique nature of the Scholte wave allowed for the measurement of fluid properties of a semi-infinite fluid using two transducers on a single substrate. Changes in water temperature, and thus sound speed, were measured and the minimum detectable change in temperature was found to be 0.1C. For fluid pumping, interdigital cMUTs were integrated into microchannels and excited with phase-shifted, continuous wave signals. Highly directional guided waves were generated which in turn generated acoustic streaming forces in the fluid. The acoustic streaming forces caused the fluid to be pumped in a single, electronically-controlled direction. For a power consumption of 43mW, a flow rate of 410nL/min was generated against a pressure of 3.4Pa; the thermodynamic efficiency was approximately 5x10-8%. Although the efficiency and pressure head are low, these transducers can be useful for precisely manipulating small amounts of fluid around microfluidic networks.

It is known from the literature that conventional voltage and current transformers measure inaccurate values for voltage and current harmonics which are parts of power quality. Maximum bandwidth of conventional current transformers, which are used in electricity transmission and distribution systems, is 1.5-2 kHz and it is lower for conventional voltage transformers. Also, it is known that / voltages in some frequency spectrum are measured higher and voltages in another frequency spectrum are measured lower by the conventional voltage transformers. Furthermore, because of the phase shift of fundamental component caused by the conventional current and voltage transformers, losses and efficiency can not be calculated accurately. In this work, through the simultaneous measurements taken at the same feeder by both conventional transformers and new technology measurement transformers / amplitude and phase shift errors which are caused by conventional transformers depending on frequency and so harmonics, are examined and evaluated. Amplitude coefficients and phase shifts are determined for different types of conventional transformers to be able to calibrate measurement deviation. Through this work, measured data by conventional transformers will be accurate and realistic in terms of harmonic components. This matter is important to determine whether the accurate limits which will be set in the future possibly concerning with harmonics and interharmonics, are surpassed or not / also for punitive sanction.

This work describes the development of an optical probe for measuring movement of tissue particles deep inside which are loaded by an ultrasound remote palpation device. The principle of the method is that ultrasound force which can be applied inside the tissue makes the tissue particles vibrate and this vibration phase-modulates the light intercepting the insoniified region which results in a modulated speckle intensity on detection outside the object. This speckle intensity modulation detected through the measured intensity autocorrelation is a measure of the vibration amplitude. Since the vibration amplitude is related to the local elastic properties of the medium, the measured modulation depth in intensity autocorrelation can be used to map the elastic property in the insonified region. In this work, first the ultrasound induced force is calculated for both plane and focused ultrasound beams, and converted to amplitude of vibration and refractive index modulation, solving the forward elastography equation. Light propagation inside an insonified object is modelled using Monte Carlo simulation and the amplitude and intensity correlations are computed. The modulation depth on the autocorrelation is estimated and shown that it is inversely correlated to the local elastic modulus and optical absorption coefficient. It is further shown that whereas the variation in modulation depth is linear with respect to absorption coefficient, the same variation with elastic property is nonlinear. These results are verified experimentally in a tissue mimicking phantom. The phantom was constructed out of poly vinyl alcohol(PVA) whose optical, mechanical and acoustic properties are independently controlled. It is also shown that for loading with focused ultrasound beam the displacement is almost along the ultrasound transducer axis and therefore the contribution from refractive index modulation alone can be ascertained by probing the insonified perpendicular to the transducer axis. This helps one to find the contribution to the modulation depth from the ultrasound-induced vibration, which can be used to compute a quantitative estimate of the elastic modulus from the modulation depth.

Thesis (M.S.)--Mississippi State University. Department of Physics and Astronomy. / Title from title screen. Includes bibliographical references.

Activation of the maternal immune system and resultant maternal cytokine expression due to prenatal infection has been implicated as a significant contributor to the pathology of neuropsychiatric and neurodevelopmental disorders such as schizophrenia and Autism Spectrum Disorder (ASD). Increased maternal interleukin-6 (IL-6) expression, observed clinically and in animal models of prenatal infection, and resultant activation of key signaling pathways, has been shown to be a biological indicator of pathology, and a central component of the pathological mechanism. In animal models of prenatal infection and clinically in pregnancy disorders hallmarked by immunological irregularities and increased IL-6 expression, inhibition of IL-6 has been shown to reduce pathological symptoms both maternally and in the exposed offspring. This study aims to demonstrate the ability of IL-6 expression, resulting from prenatal infection, to induce neuropathological and behavioral outcomes that mirror clinical observations seen in disorders such as ASD. More importantly, it shows how flavones luteolin and diosmin, a subclass of the flavonoid family, through inhibition of IL-6 mediated activation of Signal Transducer and Activator of Transcription-3 (Stat3) can reduce these pathologies both in vitro and in vivo. Evidence suggests that flavonoids, a polyphenolic class of naturally occurring plant secondary metabolites, are potent anti-inflammatory agents that can attenuate the expression of cytokines such as IL-6, possibly through the modulation of tyrosine kinase activity. They have been shown to have significant therapeutic potential in disorders hallmarked by increased inflammation or disruptions in immune regulation, such as neurodegenerative disorders and certain cancers. Members such as diosmin have also been shown to be safe during pregnancy, and are currently utilized in the treatment of certain vascular disorders associated with pregnancy. In vitro work undertaken in this study showed that co-administration of luteolin with IL-6 in neural stem cells (NSC) was able to attenuate pathological outcomes induced by IL-6 including aberrant proliferation, over expression of astroglial marker, glial fibrillary acidic protein (GFAP) and changes in cellular morphology. In vivo studies involving luteolin and diosmin further confirmed the therapeutic efficacy of these compounds as similar attenuation of IL-6 mediated maternal and fetal pro-inflammatory cytokine expression and abnormal behaviors in prenatally exposed offspring was observed. Mechanistically, these effects were mediated through inhibition of Stat3 activation although other pathways activated by IL-6 were modulated by flavone co-treatment. Flavonoid treatment during periods of prenatal infection may prove to be a therapeutic intervention for the resultant pathological outcomes seen in offspring through attenuation of the maternal and fetal immune response to infection as well as modulation of signaling pathways in the fetal brain. These compounds may prove therapeutically efficacious for the application in perinatal conditions hallmarked by increased inflammation during pregnancy.

Pressure drop across miniature-scale flow disturbances, including abrupt flow area changes, is an important source of error and confusion in the literature. Such pressure drops are frequently encountered in experiments, where they are often estimated using methods and correlations that have been developed based on experimental data obtained in conventional systems. However, physical arguments as well as the relatively few available experimental observations indicate that such pressure drops in microchannel systems are likely to be different than what is known about similar phenomena in conventional flow systems. Experimental data dealing with pressure drop associated with two-phase flow across abrupt flow area changes in microchannels are scarce, however, and the available data are insufficient for the development of reliable predictive methods. In this investigation, experiments were conducted using a test section consisting of two capillaries, one with 0.84 mm, and the other with 1.6 mm inner diameters. A multitude of pressure transducer ports were installed along the two capillaries, and allowed for the measurement of the pressure gradients over the entire test section. The test section allowed for the measurement of frictional pressure gradients in the two straight channels, as well as pressure drops caused by the flow area expansion and contraction depending on the flow direction, for single-phase as well as two-phase flows. These measurements were performed over a wide range of parameters, using air as the gaseous phase, and room-temperature water as the liquid phase. The single-phase flow data were compared with existing conventional correlations, and with predictions of CFD simulations using the Fluent computer code.

The presented work aims to optimize the performance of piezoresistive cantilevers in cases where the output signal originates either from a static deflection of the cantilever or from the dynamic (resonance) characteristic of the beam. Based on a new stress concentration technique, which utilizes silicon beams and wires embedded in the cantilever, the force sensitivity of the cantilever is increased up to 8 fold with only about a 15% decrease in the cantilever stiffness. Moreover, the developed stress-concentrating cantilevers show almost the same resonance characteristic as conventional cantilevers. The focus of the second part of the present work is to provide guidelines for designing rectangular silicon cantilever beams to achieve maximum quality factors for the fundamental and higher flexural resonance at atmospheric pressure. The applied methodology is based on experimental data acquisition of resonance characteristics of silicon cantilevers, combined with modification of analytical damping models to match the measurement data. To this end, rectangular silicon cantilever beams with thicknesses of 5, 7, 8, 11 and 17 um and lengths and widths ranging from 70 to 1050 um and 80 to 230 um, respectively, have been fabricated and tested. To better describe the experimental data, modified models for air damping have been developed. Moreover, to better understand the damping mechanisms in a resonant cantilever system, analytical models have been developed to describe the cantilever effective mass in any flexural resonance mode. To be able to extract reliable Q-factor data for low signal-to-noise ratios, a new iterative curve fitting technique is developed and implemented. To address the challenge of frequency drift in (mass-sensitive) resonant sensors, and especially cantilever-based devices, the last part of the research deals with a novel compensation technique to cancel the unwanted environmental effects (e.g., temperature and humidity). This technique is based on exploring the resonance frequency difference of two flexural modes. Experimental data show improvements in temperature and humidity coefficients of frequency from -19.5 to 0.2 ppm/˚C and from 0.7 to -0.03 ppm/%RH, respectively. The last part of the work also aims on techniques to enhance or suppress the flexural vibration amplitude in desired overtones.

Virtual three-dimensional auditory displays (V3DADs) use digital signal processing to deliver sounds (typically through headphones) that seem to originate from specific external spatial locations. This set of studies investigates the delivery of V3DADs through bone-conduction transducers (BCTs) in addition to conventional headphones. Although previous research has shown that spatial separation can be induced through BCTs, some additional signal adjustments are required for optimization of V3DADs, due to the difference in hearing pathways. The present studies tested a bone-conduction adjustment function (BAF) derived from equal-loudness judgments on pure tones whose frequencies were spaced one critical band apart. Localization performance was assessed through conventional air-conduction headphones, BCTs with only transducer correction, and BCTs with a BAF. The results showed that in the elevation plane, the BAF was effective in restoring the spectral cues altered by the bone-conduction pathway. No evidence for increased percept variability or decreased lateralization in the bone-conduction conditions was found. These findings indicate that a V3DAD can be implemented on a BCT and that a BAF will improve performance, but that there is an apparent performance cost that cannot be addressed with BAFs measured using the methodology in the present studies.