The study of the in vitro circadian oscillator of the cyanobacterium Synechococcus elongatus has uncovered a complex interplay of its three protein components. Synchronization of the clock's central oscillatory component, KaiC, has been thought to be achieved through subunit shuffling at specific intervals during the clock's period. By utilizing an established fluorescence-based analysis on completely phosphorylated and dephosphorylated mutants as well as wild-type KaiC, this study has shown that shuffling rates are largely unaffected by phosphorylation state. These findings conflict with previous reports and hence revise our understanding of this oscillator.

The highly c-axis oriented ZnO films were deposited on silicon substrates by reactive RF magnetron sputtering in this study. The optimal two-step deposition parameters for ZnO films, which are oxygen concentrations of 70 % (1st step) and 50 % (2nd step), RF power of 100 W and sputtering pressure of 25 mTorr, are obtained by means of XRD, SEM and AFM analysis. Al films are deposited under optimal deposition parameters, which are DC power of 100 W and sputtering pressure of 4 mTorr, to form IDT electrodes with low sheet resistances. Therefore, Al/ZnO/Si layered SAW devices were fabricated under these optimized manufacturing parameters. An oscillator based on a Al/ZnO/Si layered SAW device was fabricated for the application of UV detection and then investigating the acoustoelectric effect between surface acoustic wave and ultraviolet light illumination. Due to the fact that the sensor sensitivity is directly proportional to the resonance frequency, in this study the SAW device with high resonance frequency of Sezawa mode is adopted to form SAW oscillator for high sensitivity. The resonance frequency of SAW oscillator is 751.41 MHz. The optimal detecting zone for UV light is the center of IDT electrode with maximum sensitivity of 8.12 ppm/(£gW/cm2).

This thesis is composed of three parts. In the first part, various kinds of theory to account for injection locking and pulling in the available literature are studied and compared. In the second part, this thesis proposes an experimental setup with self-made hybrid VCO and commercially available equipments and components to measure the characteristics of injection locking and pulling. This thesis also performs simulation to verify the measured results. The simulation mainly relies on the circuit envelope technique that has been developed in our laboratory. Comparison between measurement and simulation shows good agreement in the injection-locking characteristic curves and the injection-pulling spectrum characteristics. In the third part, this thesis carries out an RFIC design for a fractional-N frequency synthesizer with special features on quantization-noise cancellation and PLL nonlinearity reduction using TSMC 0.13£gm CMOS process.

Broadband voltage-controlled oscillators are critical to the design of millimeter wave frequency synthesizers. This thesis proposes a design technique that can be used to significantly extend the achievable frequency span of an oscillator. A dual-band oscillator topology is described that can be configured to operate in one of two modes, by an electrical reconfiguration of the negative resistance core around the resonant tank, without switching passive elements within the tank itself. The configuration helps to minimize the difference in phase noise performance between the two modes, while achieving a wide tuning range. To verify the concept, a mm-wave VCO that operates at 30-GHz is designed in a commercial 0.18-um CMOS technology, with an approximate simulated tuning range of 20%. A dual-mode oscillator is also designed in a 0.13-um technology at 60-GHz. / text

The pathophysiology of essential tremor (ET) is not clearly understood but is thought to involve multiple brain regions. The purpose of this study was to describe in greater detail head tremor in ET and to investigate the possible relationship between head and hand tremor. Ten ET subjects were recruited (1 male, 9 female) and compared to three control subjects (1 male, 2 female). Head and hand tremors were recorded simultaneously with surface electromyography (EMG) of the wrist extensors and various neck muscles, laser displacement sensors (hand tremor), a load cell (hand tremor) and an accelerometer (head tremor). While seated, subjects performed four tasks: 1) constant force (10% maximum) wrist extensions (with and without visual feedback); maintenance of the hands in a horizontal posture against gravity while 2) seated upright in a chair, 3) seated in a reclined chair (20° backward, head not supported); and 4) seated upright in a chair and producing steady submaximal hip adduction forces. Head tremor spectral peaks were found between 3.5 and 7 Hz in neck muscle EMG and the accelerometer signal. Wrist tremor (EMG and kinematic data) was slightly higher in frequency with a range of 4 -10 Hz. Of the ten ET subjects recruited for this study, 60% (n = 6) demonstrated significant levels of coherence (p < 0.05) in at least one neck-wrist muscle comparison at the fundamental frequency of their tremor. The results demonstrated an obvious bias of the trapezius descendens (TD) muscles over the more axial neck muscles to demonstrate significant coherence with the extensor carpi radialis (ECR) muscles. Of the six neck muscles investigated, the SPLs and the SCMs were commonly driven at the same frequencies (change in frequency < 0.5), although this seldom resulted in coherence. There is indication that the oscillatory activity driving more distal muscles is different from that in the SPL and the SCM. Due to the multifunctional nature of the TD, it may be the recipient of two descending neural commands. These commands may each be of a different oscillatory frequency originating from different central oscillators. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2008-10-29 10:03:22.354

The all-solid-state (or "holosteric") optical parametric oscillator has resulted from the recent development of diode-laser-pumped solid-state lasers and from recent advancements in new optically nonlinear materials. As a result, all-solid-state sources of widely tunable (ultraviolet - visible - near infrared) coherent radiation are now possible by using the radiation from diode-laser-pumped solid-state lasers, either directly or after frequency conversion, to pump optical parametric oscillators. Such devices can be made compact, efficient and reliable. The work described in this thesis explores the feasibility of obtaining widely tunable radiation from such devices, with particular reference to low threshold, high efficiency operation, so requiring only modest energies (1 mJ in ultraviolet) from the pump source. In particular, a frequency tripled or frequency quadruped Nd:YAG laser pumped by pulsed, GaAlAs diode laser bars has been used as the pump source, and lithium triborate has been used as the nonlinear medium in the optical parametric oscillator. Two geometries of lithium triborate crystals have been investigated as the nonlinear medium. One was cut for a type II non-critical phase matching geometry, while the other was cut for a type I critical phase matching geometry. The oscillator cavities were designed for optimum focusing and mode matching aiming for operation with a low pump energy through the use of tightly focused pump radiation. The ultraviolet pump source was based on a Q-switched diode-laser-pumped Nd:YAG laser which generated pulses at 1.064 mum with energy 10 mJ and duration around 10 ns. These were then frequency up-converted to the UV at 355 nm or 266 nm, so as to be suitable for pumping the parametric oscillators. Generally, an overall conversion efficiency from 1.064 mum to 355 nm of >30% was obtained using the nonlinear materials potassium titanyl phosphate and lithium triborate for second harmonic generation and sum-frequency mixing respectively. For conversion to 266 nm, an overall efficiency of > 18 % was obtained using the nonlinear materials KTP and BBO for two step second harmonic generation. In the experimental investigations of the all-solid-state lithium triborate optical parametric oscillator pumped at 355 nm a low oscillation threshold was obtained in the type II non-critical phase matching geometry (around 0.2 mJ) and pump depletions of 50 % were obtained at around six times threshold. This device could be temperature tuned (20 - 200 &deg;C) from 457 to 481 nm (signal wave) and 1.6 to 1.35 mum (idler wave). Optimised focusing conditions corresponding to the theory of Guha et al were approached in the type I phase matching geometry, and despite the existence of a 1&deg; walkoff angle, the minimum oscillation threshold was measured to be around 0.3 mJ. Generally, pump depletions of about 35 % were obtained, at around four times threshold. These devices could be angle tuned (through crystal internal angle 14&deg;) from 457 to 666 nm (signal wave) and 1.6 mum to 768 nm (idler wave). (The whole of the range 420 nm to 2.3 mum could be covered with such a device given additional mirror sets). The all-solid-state type II geometry lithium triborate optical parametric oscillator was also pumped at 266 nm, when it was temperature tunable (20 - 200 &deg;C) from 306 to 314 nm (signal wave) and 2.03 to 1.75 mum (idler wave). Pump depletions of 25 % were demonstrated with this device at pump energies of four times threshold. In addition to the above experimental investigations, the thesis addresses the issues of (i) choice of nonlinear material for optical parametric oscillators in terms of appropriate figures of merit, and (ii) optimisation of pump and resonated wave focusing parameters. Reviews of the appropriate theoretical background to phase matching geometries and optical parametric interaction are included.

A low threshold, efficient optical parametric oscillator (OPO) based on the material Potassium Titanyl Phosphate (KTP) and pumped by a diode-laser-pumped, Q-switched Nd:YLF laser has been demonstrated and investigated. This all-solid-state device was operated in a non-critical phase match (NCPM) geometry converting the 1 mum pump light to output wavelengths of 1.54 and 3.28 mum, and has potential as an 'eyesafe' laser source with scaling to higher powers. A major contributing factor to the success of this work was the extension of the steady state theory of the singly resonant OPO to include the build-up time effects that are dominant in the pulsed regime. A number of diode pumped lasers were constructed, allowing a comparison to be made between side- and end-pumping geometries, and also between the materials Nd:YAG and Nd:YLF. The end-pumping geometry in conjunction with the higher absorption and longer upper state lifetime in Nd:YLF made it the design of choice for the case of low pump pulse energies (~ 12 mJ at 797 nm). Anamorphic expansion of the laser mode in the plane parallel to the diode laser junction was employed to achieve TEM00 operation of this laser. Subsequent Q-switching with a polariser and LiNbO3 Pockels cell combination produced 2.2 mJ at 1.047 mum in an 18 ns pulse. Investigation of the dynamic loss of the Q-switch (which is due to the elasto-optic effect) allowed improvement of laser performance. The established model for a pulsed singly resonant OPO which describes the case for a plane-plane resonator was inappropriate in this work and so the steady state focused beam theory was extended to include time dependence. Fair agreement was found between the computer model and the experimental results, where the effects of pump and signal focusing, and output coupling were investigated. The high conversion efficiency of 30% for converting the 1 mum pump light to the eyesafe wavelength of 1.54 mum is superior to the present alternative source of the Er:glass laser. Pump energy thresholds of less than 0.5 mJ were obtained, along with internal conversions approaching 50 %. An empirical relation describing pump depletion was derived which showed good agreement with experiment. A high resolution investigation of the spectral properties of the OPO identified the roles of resonant reflection and doubly resonant behaviour on the mode structure of the output. The former suggests a way in which single mode operation could be achieved without the use of additional intracavity elements, or a seeding source.

The forced vibration of a partially delaminated structure such as an aircraft wing can result in catastrophic crack growth. In order to look at the underlying mechanism of the dynamics and failure of the material, a simplified model of a cantilever beam with a single delamination at its free end is considered. We investigate a number of aspects of this system, using mathematical models to gain insight into its behaviour.

This thesis deals with the analysis and solution source for carrier frequency generator for portable radar signal simulator. This simulator is tunable in the frequency range from 2 GHz to 18 GHz and as it´s frequency source generator is used YIG oscillator for its very high frequency realignment. Simulator provides output power up to 1W on the SMA connector which can be connect to internal antenna by using jumper cable. To achieve this output power will be used by semiconductor amplifier.

Clock multipliers are among the most critical elements in high speed digital circuits. Power consumption, area, jitter and wide tuning range are key design metrics in these circuits. To provide a wide range of clock frequencies, Digitally Controlled Ring Oscillators (DCROs), whose frequencies are discretely tuned using a Frequency Code Word (FCW), have been investigated in recent studies. They have several advantages over LC-based Voltage Controlled Oscillators (VCO) including simplicity of design, small die area (i.e. no large inductors), better compatibility with deep submicron CMOS processes,ability to offer multiple output phases, and wider tuning range.A compact differential Injection Locked Clock Multiplier (ILCM) based on an injection locked DCRO is implemented in this thesis. As the transistor features continuously shrink and the supply voltage is reduced, ILCMs are becoming more prone to issues such as increased effect of random mismatch, increased device noise, susceptibility of the design to noise coupling and vulnerability to Process Voltage and Temperature (PVT) variations. Furthermore, ILCMs in recent System on a Chip (SoCs) have stringent design requirements including accurate frequency tuning, fine fractional resolution, high levels of integration and better amenability to technology scaling. In the proposed ILCM, multiple techniques were used to address deep submicron CMOS design challenges, as well as modern applications’ requirements. The design is fully digital, synthesizable and automatically placed and routed. All circuit blocks were implemented using digital design flow and designed using a Hardware Description Language (HDL). This allows the design to be more easily ported to deep submicron processes. Online or offline PVT calibration can be performed using a replica oscillator and high speed digital counters to track frequency drifts with PVT variations. A DCRO based on a matrix structure has been utilized to reduce period variations due to random mismatch. The DCRO is built up from pseudo differential delay cells to enhance design immunity to noise coupling. The key thesis contributions are implementing a new DCRO structure using fully syntheziable differential structure, utilizing a novel PVT calibrator that can compensate for frequency mismatch between the main DCRO and its replica, and using a low complexity fractional ILCM technique that achieves a fine fractional resolution with few number of ring oscillator stages.Designed in a TSMC 65 nm GP CMOS process with no analog or RF enhancements, the proposed ILCM frequency ranges from 1.0 to 1.8 GHz and occupies 124:5 m 170 m of chip area. The ILCM can operate in integer or fractional mode for multiplication ratios up to 9. At 1.7 GHz and 1.1 V, the measured integrated RMS jitter (1 kHz to 30 MHz) for the 3rd and 9th multiplication factors are 197 fs and 381 fs, respectively. The ILCM consumes 13.25 mW of power and has a fraction resolution of fref=32. Furthermore, it achieves a jitter-power FOM of −241 dB, when measured at room temperature and 1.1 V. When tested in the presence of switching noise, it provides up to 7 dB improvement in phase noise when compared to a single ended version of the ILCM. In the presence of voltage variations (from 0.9 V to 1.1 V) and temperature variations (from 30 C to 70 C), the maximum integrated RMS jitter variation observed was 50 fs.