Pour un grand nombre d'applications, les sources laser impulsionnelles femtoseconde (fs) doivent fournir des puissances toujours plus importantes. En régime impulsionnel, on recherche d'une part une forte puissance crête par impulsion, et d'autre part une forte puissance moyenne, c'est à dire un taux de répétition élevé. Parmi les technologies existantes, les amplificateurs à fibre optique dopée ytterbium présentent de nombreux avantages pour l'obtention de fortes puissances moyennes, cependant le fort confinement des faisceaux dans la fibre sur de grandes longueurs d'interaction induit inévitablement des effets non-linéaires, et limite ainsi la puissance crête accessible. Nous avons étudié lors de cette thèse la combinaison cohérente d'impulsions fs appliquée aux systèmes fibrés.Ayant déjà fait ses preuves dans les régimes d'amplification continu et nanoseconde, la combinaison cohérente de faisceaux (dite combinaison spatiale) permet de diviser une seule et unique source en N voies indépendantes, disposées en parallèle et incluant chacune un amplificateur. Les faisceaux amplifiés sont ensuite recombinés en espace libre en un seul et unique faisceau, qui contient toute la puissance des N amplificateurs sans accumuler les effets non-linéaires. Cette architecture permet théoriquement de monter d'un facteur N le niveau de puissance crête issu des systèmes d'amplification fibrés. Au cours de cette thèse, nous avons démontré la compatibilité et l'efficacité de cette méthode en régime d'amplification fs avec deux amplificateurs, selon différents procédés. Les expériences démontrent d'excellentes efficacités de combinaison ainsi qu'une très bonne préservation des caractéristiques temporelles et spatiales initiales de la source. Les procédés de combinaison cohérente nécessitent cependant un accord de phase entre différents amplificateurs stable dans le temps, assuré en premier lieu par une boucle de rétroaction. Nous avons poursuivi notre étude en concevant une architecture totalement passive, permettant une implémentation plus simple d'un système de combinaison à deux faisceaux sans asservissement électronique. Enfin, une méthode passive de combinaison cohérente dans le domaine temporel est étudiée et caractérisée dans le domaine fs, et implémentée simultanément avec la méthode passive de combinaison spatiale proposée précédemment. Ces expériences démontrent la validité et la variété des concepts proposés, ainsi que leurs nombreuses perspectives pour les systèmes d'amplification fs fibrés.

Acute and chronic sleeping sickness are fatal neglected tropical diseases caused by Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense respectively (members of the sub-genus Trypanozoon). Accurate diagnostics are needed to guide treatment since the symptoms of disease are non-specific and the drugs that are used for treatment are too toxic to be administered to unconfirmed cases. Tests need to be simple enough to confirm clinical diagnosis of sleeping sickness in poorly-resourced, peripheral health centres and for use as epidemiological tools to detect T. b. rhodesiense in the zoonotic reservoirs of infection. This study focuses upon LAMP (loop-mediated isothermal amplification) as a novel diagnostic for sleeping sickness that may serve to bridge the gap between the need for sensitive, specific molecular diagnostics on the one hand and ‘field-friendly’ diagnostics on the other. Here, two previously published LAMP assays for Trypanozoons were compared to classic PCR based methods for the diagnosis of Trypanozoon infection status in 428 cattle blood samples. The results did not support the use of LAMP as an improved system for surveillance of T. b. rhodesiense in the zoonotic cattle reservoir. T. b. rhodesiense and T. b. gambiense subspecies specific LAMP assays were evaluated against traditional reference subspecies specific PCR tests, using DNA purified from 86 cryopreserved trypanosome isolates. Novel LAMP assays for these subspecies were also designed and evaluated. Both the published and novel assays for T. b. rhodesiense (targeting different regions of the SRA gene) were sensitive, specific and reliable when applied to purified DNAs, but were less consistent on field samples. The novel T. b. gambiense LAMP (targeting TgsGP) was sensitive and specific but this was not the case for the published LAMP assay (targeting the 5.8S rRNA gene). However reliability may be less than optimal for LAMP TgsGP. Finally, simple endpoint readout methods for LAMP were evaluated. The colour change reagent hydroxynaphthol blue was identified as the best currently available method taking cost, ease of use and reliability into consideration. In 2009 the number of reported sleeping sickness cases fell below 10,000 for the first time in 50 years. Improved LAMP diagnostics could facilitate the diagnosis of sleeping sickness and support the continued fight against this neglected, but deadly disease.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Blind adaptive equalization with application for Non-Linearly Amplified (NLA) quadrature amplitude modulation (QAM) systems in multipath selective fading channels is presented. With an offset sampling strategy in the receiver, the proposed blind equalization using Constant Modulus Algorithm (CMA) exhibits a fast convergent speed for a family of quadrature modulated systems in NLA and multipath fading channels. Feher’s patented Quadrature Phase Shift Keying (FQPSK) and Feher’s Quadrature Amplitude Modulation (FQAM) which correspond respectively to 4-state and 16-state QAM are used due to their higher Radio Frequency (RF) power and spectral efficiency in NLA channel. It has been shown that blind adaptive equalization can significantly open the eye signals in multipath frequency selective fading channels.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Spectral sidelobes of QPSK, OQPSK, IJF-OQPSK, and SQAM modulated signals after nonlinear amplification are compared. It is known that OQPSK has lower spectral sidelobes than QPSK. However, in the presence of frequency selective fading, a decision-feedback adaptive equalizer is able to equalize the QPSK signal but not the OQPSK signal. By using phase pre-distortion on the OQPSK waveform before nonlinear amplification, not only is the adaptive equalizer able to equalize this signal, its spectral sidelobes are also reduced. Simulations are presented to confirm these results.

In order to study the process by which human melanoma cells achieve invasion of basement membranes, a modification of the Membrane Invasion Culture System was developed to allow the in vitro collection of invasive tumor cells from heterogeneous tumor cell populations. A significant increase in the number of double minute chromosomes was observed in metaphase nuclei of the low metastatic A375P human melanoma cells which had invaded 2 consecutive amniotic membranes over that of cells in the control groups. After 25 days in culture, the incidence of double minutes had dropped below the control range. These data indicate that an unstable gene amplification event may be part of the process by which melanoma cells execute invasion through basement membranes. A375P cells which had invaded 1, 3 and 5 consecutive basement membrane-coated filters were established and compared with the parental cell line and a highly metastatic subclonal line for the following characteristics: (a) in vitro invasive potential, (b) mRNA expression of several oncogenes, (c) expression of laminin receptor, at the (cell surface) protein and mRNA levels, and, (d) secretion of endogenous laminin. There was a progressive increase in invasive potential and expression of endogenous laminin and laminin receptor which correlated with the number of membrane-coated filters through which the A375P cells had been selected. There were significant increases in the steady-state mRNA expression of c-myc and c-fos, a decrease in c-jun, and no change in Ha-ras, that correlated with increases in the invasive and metastatic potential of the cells. A novel in vitro adhesion assay was developed to study the interaction of tumor cells with lymphatic endothelium, the first step of extravasation from the lymphatic vessel. Human tumor cells from: one primary Ewing sarcoma, two melanoma, two colon and two breast carcinomas were assayed for their ability to attach to monolayers of lymphatic endothelium. There was a clear positive correlation between the metastatic potential and attachment potential of the melanoma cell lines. Overall, these data suggested that highly fibroblastic established tumor cell lines were more adaptive in rapid adhesion than primary tumor cell cultures with a more rounded morphology.

Degenerate Oligonucleotide Primed-PCR (DOP-PCR) can potentially enhance analysis of low copy number DNA samples. Theoretically, this procedure replicates fragments of the genome that can then be used for downstream multiplex STR analysis. The objective of this study is to optimize DOP-PCR by examining ramplelongation times and cycle numbers in the non-specific amplification portion of DOP-PCR, and by modifying the degenerate primer. Additionally, other methods such as Multiple Displacement Amplification (MDA) and Low Copy Number PCR (LCN PCR) were examined for their ability to create accurate DNA profiles from low DNA input amounts. Increasing the ramplelongation times showed no effect on downstream STR amplification success. An increase of cycle number increased DNA yield, but STR amplification success was undetermined. Although modifying the degenerate primer to one with a higher degeneracy decreased DNA yield, it ultimately improved STR amplification success. In comparison studies, LCN PCR produced higher STR amplification success than MDA.

An important aspect of third-order optical nonlinearity is the intensity-dependent refractive index, where the intensity of the light itself affects the refractive index. This nonlinear effect is known as Kerr nonlinearity. In this work, a theory of amplification based on Kerr nonlinearity is developed. Kerr nonlinearity is well known to exhibit instability. Our amplification theory is based on seeding this instability. The full theory is developed to obtain the vectorial wave equations of the instability. It is shown that for materials of interest, vectorial effects are negligible across the instability regime and the scalar theory gives an accurate account of Kerr instability amplification. It is also shown that this instability analysis is a spatiotemporal generalization to four-wave mixing, modulation instability, and filamentation instability. It fact, it can be considered a seeded conical emission process. Subsequently, the theory of plane wave Kerr instability is explored. Quantitatively, the importance of pump wavelength, linear dispersive properties, and non-collinear angles for optimal amplification are demonstrated. Next, the seed beam is generalized to a finite Gaussian pulse in both time and space; the effect of a finite seed beam is quantitatively analyzed. Our analysis of Kerr instability in bulk dielectric crystals demonstrates the potential to amplify pulses in the wavelength range of ~1-14 μm. Whereas plane wave amplification is shown to extend to 40 μm in the example materials shown, material damage limits finite pulse Kerr instability amplification to about 14μm. There, seed pulse output energies in the 50 μJ range appear feasible with a ratio of pump to seed pulse energy in the range 400-500. Three key aspects of Kerr amplification are the capacity for single cycle pulse amplification, that it is intrinsically phase-matched, and its simplicity and versatility. As the Kerr instability gain profile is of Bessel-Gaussian nature in the transverse space domain, it lends itself naturally to the amplification of Bessel-Gauss beams. It is shown that pump-to-seed energy amplification that is more effcient than the Gaussian case by a factor of about 5-7. Whereas in the Gaussian case, the efficiency is on the order of about 0.15-0.2%, in the Bessel-Gaussian case it is on the order of about 1%. It is also demonstrated that Bessel-Gaussian seed beams centered at longer wavelengths than ordinary Gaussian beams may be amplified. Lastly, Bessel-Gauss beams are known to have favourable properties, such as being diffraction-free over a certain propagation range. Finally, a quantum optical theory of Kerr instability is developed. In particular, we explore a theory of the generation of ultrashort photon pairs (biphotons) from vacuum with Kerr instability.

Objective: The appropriate application of audiological measures during paediatric hearing aid (HA) fitting ensures the fitting is effective and provides speech audibility across the frequency range. Audiological assessment may include both behavioural and objective measures, such as auditory brainstem response (ABR) and auditory steady-state response (ASSR). ABR and ASSR measures however do not have a 1:1 correlation with behavioural measures, and correction values need to be applied to estimate behavioural thresholds prior to HA fitting. No study has previously described how South African audiologists are utilising ABR and ASSR results during paediatric HA fitting. This study aimed to describe the current South African audiological clinical practice for paediatric HA fitting, with specific reference to the application of ABR and ASSR measures. Design: The study employed a quantitative, non-experimental, descriptive, cross-sectional survey research design. Study sample: Thirty-four personal interviews with audiologists were completed, seven within the private health sector and 27 within the public health sector. Results: Results indicated that limited departmental protocols exist and adherence to available protocols was questioned. There was a lack of consensus regarding the application of correction values to ABR and ASSR measures for HA fitting and the values utilised often differed significantly from recommended guidelines. There appeared to be an over-reliance on electrophysiological measures for paediatric audiological assessment, as well as a lack of adherence to recommended age-appropriate assessment guidelines. Conclusion: Findings suggest the need for promoting improved clinical practice and knowledge within the area of paediatric audiology in South Africa. The need for the development of nationally-agreed guidelines was highlighted.

by Au Lai Yin, Cathy. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 50-66). / Chapter I. --- ABSTRACT --- p.i / Chapter II. --- ACKNOWLEDGMENTS --- p.iii / Chapter III. --- TABLE OF CONTENTS --- p.iv / Chapter IV. --- LIST OF TABLES --- p.viii / Chapter V. --- LIST OF FIGURES --- p.x / Chapter VI. --- INTRODUCTION --- p.1 / Chapter VII. --- LITERATURE REVIEW --- p.3 / Chapter A. --- Mycobacterial tuberculosis Infections --- p.3 / Chapter B. --- Diagnostic Criteria forM .tuberculosis Infections --- p.3 / Chapter C. --- Mycobacteriological Laboratory Investigations for M. tuberculosis --- p.4 / Chapter 1. --- Conventional methods --- p.4 / Chapter 2. --- Rapid methods --- p.4 / Chapter D. --- Polymerase chain reaction (PCR) - the Principle --- p.5 / Chapter E. --- Application of PCR for Detection of M. tuberculosis --- p.6 / Chapter 1. --- Choice of target sequences --- p.6 / Chapter 2. --- Choice of method for the detection & identification of PCR-amplified product --- p.7 / Chapter 3. --- Studies on pure cultures --- p.9 / Chapter a. --- Detection limit - target DNA --- p.9 / Chapter b. --- Detection limit - Colony forming units --- p.9 / Chapter c. --- Detection limit - Number of cells --- p.10 / Chapter 4. --- Studies on clinical specimens --- p.10 / Chapter 5. --- Problems --- p.12 / Chapter a. --- Availability of target DNA --- p.13 / Chapter (i) --- Cell breakage efficiency --- p.13 / Chapter (ii) --- Target sequence --- p.14 / Chapter b. --- Inhibitory factors for Taq polymerase --- p.14 / Chapter c. --- Contamination --- p.15 / Chapter VIII. --- MATERIALS AND METHODS --- p.16 / Chapter A. --- Bacterial Strains and Strain Maintenance --- p.16 / Chapter 1. --- Reference Strains --- p.16 / Chapter 2. --- Clinical isolates --- p.16 / Chapter B. --- Growth media and culture conditions --- p.17 / Chapter C. --- Restriction Fragment Length Polymorphism (RFLP) --- p.17 / Chapter 1. --- Extraction of chromosomal DNA from M. tuberculosis --- p.18 / Chapter 2. --- Digestion of chromosomal DNA by PVU II --- p.19 / Chapter 3. --- Separation of digested DNA fragment by electrophoresis --- p.19 / Chapter 4. --- Southern Blotting --- p.19 / Chapter 5. --- Preparation of DNA probes by Polymerase Chain Reaction --- p.20 / Chapter 6. --- Hybridization --- p.21 / Chapter 7. --- Detection --- p.21 / Chapter D. --- Assessment of number of organisms --- p.22 / Chapter 1. --- Viable cell count --- p.22 / Chapter 2. --- Direct cell count --- p.22 / Chapter E. --- Assessment of the presence of IS6110/986 in M. tuberculosis isolates --- p.23 / Chapter F. --- Human leukaemic monocytic cell line (THP-1) --- p.23 / Chapter 1. --- Growth media and maintenance --- p.23 / Chapter 2. --- Culture Conditions --- p.24 / Chapter 3. --- Uptake of M. tuberculosis --- p.24 / Chapter G. --- Cell breakage and DNA extraction methodologies --- p.25 / Chapter H. --- Polymerase chain reaction (PCR) methodologies --- p.28 / Chapter 1. --- Primer and probe --- p.28 / Chapter 2. --- PCR conditions --- p.28 / Chapter 3. --- Detection --- p.29 / Chapter I. --- Patients and Clinical specimens --- p.30 / Chapter 1. --- Patients recruitment --- p.30 / Chapter 2. --- Clinical specimens --- p.30 / Chapter IX. --- RESULTS --- p.32 / Chapter A. --- "Development or Selection of a ""Standardized"" PCR Protocol for the Detection of M. tuberculosis Using Pure Cultures In Vitro" --- p.32 / Chapter 1. --- Selection of organisms for verification of the PCR protocol --- p.32 / Chapter 2. --- Optimization of the PCR conditions --- p.32 / Chapter 3. --- Detection limit of target DNA using the PCR procedure --- p.33 / Chapter B. --- Initial Screening of Six Different Cell Breakage Procedures Using Pure Cultures of M. tuberculosis Isolates TB19 &22a Based on Detection Limits of Colony Forming Units and Number of Cells --- p.34 / Chapter C. --- Comparison of Method 1 and Method 2 Based on Detection Limits of Colony Forming Units and Number of Cells Using Pure Cultures of the Eight Clinical Isolates of M. tuberculosis with variable copies of IS6110/986 --- p.34 / Chapter D. --- Detection of M. tuberculosis Isolates Within Macrophages --- p.35 / Chapter 1. --- Uptake of M. tuberculosis cells by THP-1 --- p.35 / Chapter 2. --- Comparison of the Six Different Cell Breakage Procedures Using Pure Cultures of M. tuberculosis Isolates TB19 & 22a Phagocytized by Activated THP-1 Macrophages --- p.35 / Chapter 3. --- Comparison of Method 1 and Method 2 Using Pure Cultures of the Eight Clinical Isolates of M. tuberculosis Phagocytized by Activated THP-1 Macrophages --- p.36 / Chapter E. --- Analysis of Clinical Specimens Using Method 1 & 2 with the Optimized PCR Protocol --- p.36 / Chapter 1. --- Bronchial Aspirate & Bronchoaveolar Lavage Fluid --- p.36 / Chapter 2. --- Pleural Fluid --- p.37 / Chapter 3. --- Tissue --- p.37 / Chapter 4. --- Sputum --- p.38 / Chapter 5. --- Cerebrospinal Fluid --- p.38 / Chapter X. --- DISCUSSION --- p.39 / Chapter A. --- Selection of IS6110/986 for DNA amplification --- p.39 / Chapter B. --- Optimization of PCR conditions reflected by detection limit of target DNA --- p.40 / Chapter C. --- Selection of cell breakage methods based on detection limits of CFU and/or number of mycobacterial cells --- p.41 / Chapter D. --- Application of Methods 1 & 2 and the optimized PCR protocol for clinical specimens --- p.43 / Chapter 1. --- Bronchial aspirates and bronchoaveolar lavage fluids --- p.43 / Chapter 2. --- Pleural fluids --- p.44 / Chapter 3. --- Tissues --- p.45 / Chapter 4. --- Sputa --- p.46 / Chapter 5. --- Cerebrospinal fluids --- p.46 / Chapter XI. --- CONCLUSION --- p.48 / Chapter XII. --- LITERATURE CITED --- p.50 / Chapter XIII --- TABLES --- p.67 / Chapter XIV. --- FIGURES --- p.85

Low-template deoxyribonucleic acid (DNA) samples are commonly found within forensic biological evidence. Low amounts of DNA become increasingly difficult to analyze as the allelic peaks become less distinguishable from instrumental noise. Forensic laboratories currently try to increase allele signal intensity through additional polymerase chain reaction (PCR) cycles or enhancing capillary electrophoresis injection times or potentials. Purification of the post-PCR product may also be conducted as PCR reagents can compete with DNA fragments during electrokinetic injection. Though these strategies have proven useful, resulting in a higher signal to noise ratio, low-template samples continue to exhibit allele drop-out due to the stochastic variation induced by the forensic DNA laboratory process. Further complicating analysis is the fact that low-template DNA samples are often exhausted as the full amount is needed for analysis. Thus, PCR can be considered a destructive technique. Since allele drop-out is hypothesized to be the result of 1) insufficient levels of amplicons and 2) sampling effects, it is desirable to obtain the original DNA template after amplification for future analysis. This would minimize the impact of 1) above. Thus, a novel method which isolates genomic DNA after PCR amplification has been developed. Amplification products were produced using biotinylated primers and cleaned from the solution with streptavidin-coated magnetic beads. Filtration was then used to remove remaining PCR reagents and primers. The result is a recovered sample containing the original genomic DNA. Re-amplification was then performed showing the method is successful. Although the method is capable of re-amplifying isolated DNA after PCR, there are points within the procedure that need to be optimized. For example, significant amounts of DNA are lost during the cleaning process and there is a high retention of the original amplified product. This study describes the optimization steps taken to reduce DNA loss, specifically through the filtration step. When method optimization is complete, low-template DNA samples could be analyzed recursively without being destroyed during PCR.