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A novel fabrication process is presented which allows for three-dimensionally independent features to be etched in silicon using SF6 gas in a deep reactive ion etcher (DRIE) after a single etch step. The mechanism allowing for different feature depths and widths to be produced over a wafer is reactive ion etch lag, where etch rate scales with the exposed feature size in the mask. A modified Langmuir model has been developed relating the geometry of the exposed areas in a specific mask pattern as well as the etch duration to the final depth and width of a channel that is produced after isotropic silicon etching. This fabrication process is tailored for microfluidic network design, but the capabilities of the process can be applied elsewhere. A characterization of an Alcatel DRIE tool is also presented in order to enhance RIE lag by varying etch process parameters, increasing the variety of channel sizes that can be fabricated. High values of flow rate, coil power, and pressure were found to produce this effect. The capability of the modeled process for creating a microchip cooling device for high-heat flux applications was also investigated. Using meander channels, heat flux in excess of 100W/cm2 were cooled using 750µL/s flow rate of water through the chip. This single-mask process reduces risk of damage to the chip and provides the capability to cool high-heat-flux microprocessors for the next 10 years, and for an even longer time once the geometry of the channels is optimized. / Master of Science

Cette thèse présente des développements techniques et méthodologiques visant une alternative viable pour le traitement des cancers digestifs (rectum, œsophage). Par rapport aux méthodes standards de thérapie, les ultrasons de contact de haute intensité sous guidage IRM sont une approche moins invasive. L’IRM offre 2 avantages: bonne résolution spatiale et contrôle en temps réel de la température. Cette méthode de traitement demande efficacité et sécurité. Trois prototypes d’antenne RF intégrées à des transducteurs ultrasonores ont été réalisés afin d’améliorer la résolution spatiale et temporelle des images IRM et la précision de la mesure de température. Les antennes intégrées ont montré une meilleure sensibilité par rapport à une antenne extra corporelle standard. Des images IRM haute résolution, anatomiques (voxel0.4x0.4x5 mm3) et de thermométrie (voxel 0.75x0.75x8 mm3, 2s/image) ont été acquises in-vivo.La température a été mesurée, dans un rayon de 20 mm au-delà du ballon, avec un écart type<1°C. Les artéfacts de flux causés par l’eau circulante à l’intérieur du ballon de refroidissement ont pu être projetés hors de la région d’intérêt. L’évolution de la température a été contrôlée automatiquement, à des profondeurs variables, avec un point de contrôle par faisceau. Le contrôleur a montré une grande précision in-vivo (écart type <5%). Le transducteur ultrasonore matriciel permet d’activer successivement plusieurs faisceaux pendant la même dynamique de tir.Des simulations ont été conduites afin de proposer une planification du traitement optimale pour une tumeur désignée. Un nouveau concept de sonde ultrasonore à 256 éléments avec focalisation géométrique naturelle a été proposé. / This thesis presents technical and methodological developments aiming tooffer a viable alternative for the treatment of digestive cancers (rectum and esophagus). Compared to the standard methods of therapy, the high intensity contact ultrasound guided by MRI is a less invasive approach. MRI offers 2 advantages: good spatial resolution, and real-time temperature control. This treatment method requires efficacy and safety. Three prototypes of RF coil integrated with ultrasound transducers were built in order to increase the spatial and temporal resolution ofthe MR images, and the accuracy of the temperature measurement. The integrated coils showed a better sensitivity compared to a standard extracorporeal coil. Anatomical (voxel 0.4x0.4x5 mm3)and thermometry (voxel 0.75x0.75x8 mm3, 2s/image) high resolution MR images were acquired in-vivo. The temperature was measured, within a radius of 20 mm from the balloon, with a standard deviation <1°C. The flow artifacts caused by the water circulating inside the cooling balloon could be shifted out of the region of interest. The temperature evolution was controlled automatically, at different depths, with one control point per beam. The controller showed a good accuracy during in-vivo experiments (standard deviation less than 5%). The phased-arrayultra sound transducer permits the successive activation of multiple beams during the same dynamic of sonication. Simulations were conducted in order to offer an optimal treatment planning for a defined tumor. A new design of ultrasound transducer with 256 elements with revolution symmetry, based on a natural geometrical focalization, was proposed.

Fusarium oxysporum Schl. var. vanillae (Tucker) Gondon is known to cause root rot in Vanilla planifolia Andrews in most regions where it is grown, including the major plantations in Xishuangbanna, Yunnan Province of China. This is of serious economic concern to the Province since the vanilla flavouring extractable from the beans of the plant is a valuable food product and an important export commodity. There are no fungicides registered for the control of Fusarium root rot and the only available chemical control methods are ineffective and cause serious contamination of the soil. Breeding for resistance is difficult when no dominant gene is known or where little information is available on fungal pathogenicity. Biocontrol is the main alternative for disease control in this crop, an attractive approach because of increasing concerns for environmental protection. The investigation considers two biocontrol strategies: first the introduction of virulent, antagonistic, non-pathogenic strains, closely-related to the pathogen, to overcome pathogenic populations in infected soils; second the use of essential oils with antimicrobial properties when applied to infected soils. Pathogenicity tests have been done on 81 out of 87 F. oxysporum isolates collected in Yunnan Province. Among these, 32 isolates were non-pathogenic and 49 were pathogenic. The pathogenicity results showed the complexity of F. oxysporum in Yunnan. Seventeen isolates were recovered from the Daluo plantation, of which 14 were pathogenic isolates and 3 non-pathogenic isolates; 26 from the Menglun plantation, in which 12 were pathogenic and 14 were non-pathogenic; 18 isolates from the Manjingdai plantation, in which 12 isolates were pathogenic, whilst the other 6 were non-pathogenic and 20 were obtained from the plantation in Hekou i County, of which 11 were pathogenic isolates and 9 were non-pathogenic. Genetic diversity within this population of F. oxysporum has been investigated with respect to vegetative compatibility and to determine the relationship between VCGs and virulence. The VCG results showed that the 87 strains of Fusarium oxysporum f.sp vanillae isolated from Yunnan Province were complex. They could be distributed into 12 different VCGs and that a direct relationship between VCGs group and virulence could not be drawn. Two non-pathogenic strains, ML-5-2 and HK-5b-4-1, have been screened from 87 strains as candidate biocontrol agents by pathogenicity and VCG, which are self-incompatible and closely related to the pathogens. These two strains were effective in vanilla root rot control in controlled environments, but their effects in field experiments were less conclusive. Seven essential oils, which have long been regarded as having inhibitory effects on pathogens in nature, have also been investigated as biocontrol agents. Three oils, cinnamon oil, thyme oil and clove oil, were effective in inhibiting the growth of pathogen in vitro. These oils may develop into useful components of different management strategies with non-pathogenic strains. For the future, consideration will need to be given to the mechanism(s) of the interaction of the antagonistic components with the soil microbe population and host plant and also to appropriate formulation, to take account of soil type, crop status, cultural practices, environmental and economic factors. Biocontrol methods have considerable potential but must be acceptable to farmers as part of an overall crop management programme.

In order for stroke subjects to gain functional recovery of their hemiparetic limbs, facilitation techniques such as the repetitive facilitation exercise, or RFE, have been developed. Currently, there is a lack of understanding of the neural mechanisms associated with these types of facilitation techniques. To better understand the neural mechanisms associated with the RFE a functional magnetic resonance imaging (fMRI) study should be conducted. This thesis presents experimental results testing the feasibility of implementing an fMRI-compatible actuator to facilitate a myotatic reflex in synchronization with the subject’s intention to move their hemiparetic limb. Preliminary data from a healthy individual demonstrated the feasibility of overlapping the long latency component of the afferent myotatic reflex, created by electrical stimulation, with descending nerve impulses, created using transcranial magnetic stimulation, in a time window of 15ms. In addition, a pneumatic actuation time delay due to long transmission line was evaluated. The pneumatic actuator met the timing precision requirement for the rehabilitation device for varying transmission line lengths. Therefore a pneumatic actuation system was chosen for the rehabilitation device. This thesis will also presents on the design of an fMRI-compatible pneumatic actuator device to excite a stretch reflex response. Initial, experimental results with the device demonstrated that the designed pneumatic device can control the timing of the muscle response with a fixed signal within the required 15ms window required for cortical facilitation, which was found in the previous feasibility study. However, the device was unable to create a long latency reflex observable at the muscle. Finally, this thesis presents on the capability of the device in creating subthreshold long latency response with precision to overlap with a subthreshold descending nerve impulse, created using transcranial magnetic stimulation. The overlap of the two responses was evaluated by comparing the amplitude of the muscle response with and without the stretch reflex, created by the fMRI-compatible pneumatic actuator device. Varying time delays were analyzed.

This thesis reports on a new implementation of high quality factor (Q) copper (Cu) inductors on CMOS-grade (10-20ohm.cm) silicon (Si) substrates using a fully CMOS-compatible process. A low-temperature (less than300C) fabrication sequence is employed to reduce the loss of Si wafers at RF frequencies by trenching the Si substrate. The high aspect-ratio (30:1) trenches are subsequently bridged over or refilled with a low-loss material to close the open areas and to create a rigid low-loss island (Trenched Si Island) on which the inductors can be fabricated. The method reported here does not require air suspension of the inductors, resulting in mechanically-robust structures that are compatible with any packaging technology. The metal loss of inductors is reduced by electroplating thick (~20m) Cu layer. Fabricated inductors are characterized and modeled from S-parameter measurement. Measurement results are in good agreement with SONNET electromagnetic simulations. A one-turn 0.8nH Cu inductor fabricated on a Trenched Silicon Island (TSI) exhibits high Q of 71 at 8.75 GHz. Whereas, the identical inductor fabricated on a 20um thick silicon dioxide (SiO2) coated standard Si substrate has a maximum Q of 41 at 1.95GHz. Comparing the Q of inductors on TSI with that of other micromachined Si substrates reveals the significant effect of trenching the Si in reduction of the substrate loss. This thesis outlines the design, fabrication, characterization and modeling of spiral type Cu inductors on the TSIs.

ABSTRACT EFFECTS OF VERTICAL EXCITATION ON SEISMIC PERFORMANCE OF HIGHWAY BRIDGES AND HOLD-DOWN DEVICE REQUIREMENT Domani&ccedil / , Kemal Arman M.S., Department of Civil Engineering Supervisor: Assist. Prof. Dr. Alp Caner February 2008, 152 pages Most bridge specifications ignore the contribution of vertical motion in earthquake analyses. However, vertical excitation can develop significant damage, especially at bearing locations as indeed was the case in the recent 1999 izmit Earthquake. These observations, combined with recent developments in the same direction, supplied the motivation to investigate the effects of vertical component of strong ground motion on standard highway bridges in this study. Reliability checks of hold-down device requirements per AASHTO Bridge Specifications have been conducted in this context. Six spectrum compatible accelerograms were generated and time history analyses were performed to observe the uplift at bearings. Selected case studies included precast pre-stressed I-girders with concrete slab, composite steel I-girders, post-tensioned concrete box section, and composite double steel box section. According to AASHTO specifications, hold-down devices were required in two cases, for which actual forces obtained from time history analyses have been compared with those suggested per AASHTO. The only non-linearity introduced to the analyses was at the bearing level. A discussion of effects on substructure response as well as compressive bearing forces resulting from vertical excitation is also included. The results of the study confirmed that the provisions of AASHTO governing hold-down devices are essential and reasonably accurate. On the other hand, they might be interpreted as well to be suggesting that vertical ground motion components could also be included in the load combinations supplied by AASHTO, especially to be able to estimate pier axial forces and cap beam moments accurately under combined vertical and horizontal excitations.

This thesis discusses brain-based methodology and how educators can use brain-based techniques to impact, support, and advance cognitive growth. Current research on learning and memory is enabling educators to better understand how the brain learns and what environmental factors assist in or detract from student learning. Brain-based learning techniques are considered by brain-based researchers as one way to create a learning environment that fosters student learning at individual academic levels while concurrently challenging each student and promoting academic growth. Teachers can further student academic advancement through the direct manipulation of the classroom environment rather than by purchasing a particular program that promises results.