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No description available.

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We have developed a probe to measure specific heat of Gd-doped PbMo(_6)S(_8), at low temperatures in high magnetic fields up to 12.5 T using a heat pulse method and an a.c. technique. Comparison between these heat capacity measurements and transport measurements provides critical complimentary information about fundamental thermodynamic properties and granularity m superconductors. We have used a tiny, robust, highly sensitive and broadly field independent Cemox thermometer (CX-1030), eliminating the use of bulky gas thermometry or capacitance thermometry. The diameter of the probe is 20 min which facilitates use in our 17 T high field magnet and in free-standing cryostats. Experiments include accurate measurement of temperature oscillations of 10(^-6)K. The measurements and analysis of the data were made fully computer controlled. Measurements on Cu and NbTi demonstrate we achieved an accuracy of ±0.2 K in temperature and a typical accuracy of -10% m the specific heat values quoted. Gd-doped Lead Chevrel phase material Pb(_1-x)Gd(_x)Mo(_6)S(_8) has been fabricated in a controlled environment using simple sintering methods and a Hot Isostatic Press (HIP) operating at pressures up to 2000 atmospheres. Cp has been measured and the properties of the materials including B(_c2)(T) have been determined. HIP processing improves the materials, increasing Tc ~ 15 K and B(_c2)(0) ~ 60 T. These values are amongst the best reported values for the Chevrel phase materials to date. I am personally responsible for taking all the data and its analysis. The modification of the probe were also undertaken by me. The fabrication of the samples was not my work

Context: Polycystic ovary syndrome (PCOS) is complex disorder associated with many metabolic abnormalities. PCOS is one of the most common endocrine disorders occurring in women of reproductive age and affects about 6-7% of the population. Women with PCOS have insulin resistance and hyperinsulinemia, thus increasing their risk of developing Type 2 diabetes mellitus, dyslipidemia, hypertension, cardiovascular disease, and endometrial cancer Overall Objective: To compare anthropometric features (weight, BMI, WC, body fat percent), antral follicle count (AFC), fasting glucose and insulin levels, HOMA score, menstrual bleeding patterns, and abdominal adiposity before and after a dietary intervention. Materials and Methods: The work presented herein represents a subset of the data being analyzed in an ongoing study titled "Lifestyle Intervention for Women with Polycystic Ovary Syndrome: The Role of a Pulse-Based Diet and Aerobic Exercise on Infertility Measures and Metabolic Syndrome Risk". PCOS was diagnosed by two of the three diagnostic criteria as defined by the Rotterdam consensus: a history of cycles >35 days in length, hyperandrogenism as defined by a Ferriman and Gallwey score of >6 or hyperandrogenemia, as well as polycystic ovaries (PCO), defined by >25 follicles visualized upon transvaginal ultrasonography (TVU). Participants were randomized to either a 16 week pulse-based diet or to a TLC diet for 16 weeks. All participants were asked to follow an exercise program for the 16 week duration of the intervention. Changes in demographic, anthropometric features AFC, fasting insulin levels, and intervals between menstrual cycles were assessed. Results: Twenty four women completed the 16 week dietary intervention to date (pulse n=13, TLC n=11). Participants were found to be similarly matched for age, weight, BMI, WC, and FAI. Weight (p=0.002) and body fat (p=0.0004) decreased significantly. No significant differences were detected in BMI and waist circumference. Antral follicle counts were decreased in the right ovary (p=0.04) but not the left ovary (p=0.11). There was no change in fasting glucose levels detected. There was a decrease in fasting insulin levels (p=0.02) and in HOMA score (p=0.02). No change in abdominal adiposity was detected (p=0.88). There was a tendency toward a change of fasting insulin levels and HOMA score due to the pulse-based diet. The average interval between menses decreased after the intervention (p=0.04). The longest length of time between menses also decreased after the intervention (p=0.01). Conclusions: Our hypothesis was partially supported. We observed significant decreases in weight, body fat percent, AFC in the right ovary, fasting insulin levels and intermenstrual intervals. In most women, the decreased intermenstrual interval translated into the resumption of menstrual cyclicity. However, the participants' BMI, WC, AFC in the left ovary, and abdominal adiposity were not affected. Consuming food of a lower glycemic index without a calorie restriction may help women with PCOS gain healthier anthropometric profiles, decrease serum insulin levels and insulin resistance, and increase the regularity of menstrual cycles. Further study involving weight reduction and dietary intervention with pulses may prove to be more successful than calorie reduction alone.

The main focus of this investigation was to get a greater understanding of the effect of combustion frequency, positive pressure amplitude, relative air:fuel ratio (A), water jacket temperature and input firing rates on the emissions of NO from pulse combustors. This study was carried out by a programme of experimental work combined with the development of a one-dimensional model. Results obtained in this study from experimental measurement, revealed evidence that a Schmidt tube has the ability to operate over a wide range of parameters (such as operating frequency, positive pressure amplitude, relative air:fuel ratio, water jacket temperature and input firing rates) with variable NO emissions. It was found that the level of NO emissions became lower with increasing operating frequency and positive pressure amplitude. As an example, when the rig was operated at input firing rate 25 kW and a positive pressure amplitude of 0.12 bar, increasing the frequency from 35 Hz to 73 Hz produced a monotonic reduction in NO emissions from 61 ppm to 29 ppm (dry, 3% O2). An'increase in positive pressure amplitude from 0.05 to 0.12 bar produced a change in NO emissions from 46 ppm to 34 ppm. It was also found that the values of NO emissions fell. with increasing excess air for A> 1.1. However, NO emissions increased with increasing water jacket temperature (Tw) along the length of tail pipe and with increasing input firing rates. Experimental results showed that the positive pressure amplitude was not dependent on the wall jacket temperature. However, the operating range of stable pressure oscillation could be extended from [...continued].

Pulse time modulation (PTM) techniques have drawn considerable attention over the years as suitable schemes for transmission of information over optical fibres. PTM schemes are known to utilise the vast optical bandwidth to provide efficient transmission characteristics. Pulse code modulation is one such modulation scheme that has been used widely in various communication systems. In this thesis digital pulse interval modulation (DPIM), a form of PTM, is proposed as a suitable modulation scheme for optical communication systems. In this scheme the information is represented by means of varying the anisochronous frame interval between two successive pulses. Each pulse fulfils the dual role of representing the frame boundaries and initiation of the next sampling event within the modulator or sample reconstruction in the demodulator. In this study DPIM frame structure is proposed and sampling criteria, information capacity, bandwidth requirements are discussed in depth. The spectral behaviour of the scheme is investigated and a mathematical model is developed to represent the spectra. The model was numerically evaluated and verified with the practical measurements to prove its validity. Spectral predictions were made for random as well as periodic information signals showing the existence of the distinct slot frequency component, which is used for slot synchronisation. Frame synchronisation is not required as DPIM has self synchronised frame structure. For random signals, slot component is found to be about 15 dB and for periodic single tone sinusoidal signal this was at about 5 dB. Dependency of this component on the various system parameters such as bit resolution, pulse width, pulse shape are discussed. A detailed account of the receiver performance is given. Receiver analysis was carried out for narrow band as well as for wide band channels. Possible error sources are presented and the system performance degradation with these error sources is discussed and a comparison is made with isochronous DPPM and PCM. For performance evaluation of analogue systems, signal-to-noise ratio was mathematically modelled and compared with PCM. This analysis showed that DPIM SNRs shows three important regions as compared to PCM. That is when the SNR is inferior, superior and identical to PCM performance. Threshold levels corresponding to the above regions vary depending on the system bit resolution. A prototype DPIM system was designed and implemented to transmit low speed analogue signal (≈15 kHz) at bit resolutions of 4, 5 and 6 where the slot frequencies are at 510, 990 and 1950 kHz, respectively. Measurements were carried out in order to verify the predicted performance. This results showed close agreement with the predicted. Receiver sensitivity of the prototype at bit error rate of 10^-9 was found to be about -45.5 dBm at all three cases with transmitted average power of -28.8 dBm allowing high optical power budget. The signal-to-noise ratio threshold level of the system was at -47 dBm. Finally, linearity measurements of the overall system were made at the above bit resolutions and the quantitative and qualitative results are presented.