CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / Seja I : ∑n → Mn+1 uma imersÃo de uma variedade conexa n-dimensional ∑ em uma variedade Riemanniana completa conexa (n + 1)-dimensional M sem pontos conjugados. Suponha que a uniÃo das geodÃsicas tangentes a I nÃo cobrem M. Sobre essa hipÃtese temos dois resultados: 1. Se a cobertura universal de ∑ Ã compacta, entÃo M Ã simplesmente conexa. 2. Se I Ã um mergulho prÃprio e M Ã simplesmente conexa, entÃo I(∑) Ã um grÃfico normal sobre um subconjunto aberto de uma esfera geodÃsica. AlÃm disso, existe um conjunto estrelado aberto A M tal que A Ã uma variedade com fronteira I(∑). / Let I : ∑n → Mn+1 be an immersion of an n-dimensional connected manifold ∑ in an (n + 1)-dimensional connected completed Riemannian manifold M without conjugate points. Assume that the union of geodesics tangent to I does not cover M. Under these hypotheses we have two results: 1. M is simply connected provided that the universal covering of ∑ is compact. 2. If I is a proper embedding and M is simply connected, then I(∑) is a normal graph over an open subset os a geodesic sphere. Furthermore, there exists an open star-shaped set A M such that A is a manifold with the boundary I(∑).

This dissertation represents a study on Ceratocystis spp. with hat-shaped ascospores. Previously only six species of Ceratocystis with this spore form were known. These include C. fimbriata, C. pirilliformis, C. albofundus, C. moniliformis, C. moniliformopsis and C. acericola. In this study, we have discovered and tentatively described three new species with hat-shaped ascospores. One of these group with the larger C. fimbriata clade, while the other two reside within the larger C. coerulescens clade. Chapter one provides a concise summary of the literature pertaining to the genus Ceratocystis. The intention of the chapter is to introduce readers to this important genus of plant pathogens and to provide a background regarding their taxonomy, ecology, biochemistry and variation in species. Emphasis is placed on the distinction of Ceratocystis from Ophiostoma, as ell as on those Ceratocystis spp. with hat-shaped ascospores that negatively impact upon plantation forestry species. This chapter shows how Ceratocystis spp. associated with hardwood species in commercial forestry plantations have increased in number and it provides the background for research presented in the following five chapters. In the second chapter of this dissertation, a new species of Ceratocystis was discovered amongst isolates from the Himalayan mountain range of Bhutan. This fungus, in association with the bark beetle Ips schmutzenhoferi, is responsible for large-scale deaths of Himalayan spruce trees in Bhutan. The fungus is morphologically very similar to C. moniliformis and C. moniliformopsis, but differences in culture morphology, survival at different incubation temperatures and DNA sequence data based on three different gene regions supported the fact that this is a unique species. The fungus has thus been tentatively described as Ceratocystis bhutanensis prov. nom. In chapter 3, I consider isolates of a Ceratocystis sp. recently discovered associated with dying clove trees in Northern Sulawesi, Indonesia. The fungus was found at a very high level of incidence, but was at first identified as C. fimbriata, based on morphological characteristics. Differences were observed in cultures of this fungus when they were compared with C. fimbriata especially in terms of colony colour and growth at different temperatures. Morphological differences were also observed when the clove fungus was compared with C. fimbriata isolates. When three different DNA gene regions were sequenced and compared, it was clear that this fungus represents a new species. The fungus is, therefore, tentatively described as Ceratocystis polychrome prov. nom. in this dissertation. Ceratocystis polychrome prov. nom. Isolates obtained from cloves in Sulawesi displayed three distinctly different culture morphologies. In Chapter 4 of this dissertation we used DNA sequence data and microsatellite markers to consider whether these differences could be observed at the molecular level. Comparisons of sequence data for the ITS region gave no distinction between any of the morphological groups. A total of 50 isolates were studies using microsatellites markers developed for C. fimbriata. No distinction could be obtained between isolates representing the three different culture morphological groups. The 50 isolates were subsequently treated as one population in further analyses. With the aid of the microsatellite markers, it was shown that this population probably originated from Sulawesi and that it benefits form sexual outcrossing. In chapter five of this dissertation, a study was undertaken to consider the taxonomic status of C. moniliformis. Consideratble variation has been noted in different descriptions of this species. It also has a very wide host and geographic distribution raising speculation that C. moniliformis represents a species complex rather than a single taxon. Based on morphological and DNA sequence data from three gene regions, isolated from Sumatra were described as a new species, which we have tentatively named C. tribiliformis prov. nom. The other C. moniliformis isolates were all the same, despite the fact that they originated from a wide range of hosts and areas. The fungus correctly bearing the name C. moniliformis, C. moniliformis sensu stricto, therefore does not seem to tepresent a species complex. Species such as the closely related C. tribiliformis prov. nom., C bhutanensis prov. nom., C. omanensis prov. nom. and C. moniliformopsis all belong to the larger C. moniliformis sensu lato group, and all have hat-shaped ascospores, conical spines on the ascomatal bases, disc-shaped bases to the ascomatal necks and are phylogenetically closely related to C. moniliformis. Studies presented in this dissertation provide considerable new knowledge regarding various Ceratocystis spp. with hat-shaped ascospores. Three new species are described and I have also been able to show that C. moniliformis sensu stricto is monophyletic. Two of the species (C. tribiliformis prov. nom. and C. bhutanensis nom. prov.) group within the larger C. coerulescens clade while C. polychrome prov. nom. groups within the larger C. fimbriata clade. Studies in this dissertation have also improved our knowledge of the identity of several species previously incorrectly identified as either C. moniliformis or C. fimbriata. What has clearly emerged from this dissertation is the need for a monograph of Ceratocystis to include all new species and to thoroughly consider the population biology and ecology of all species. / Dissertation (MSc)--University of Pretoria, 2008. / Microbiology and Plant Pathology / MSc / Unrestricted

Printed lens antennas offer the possibility of realizing shaped beam patterns using no more complexity than is required for pencil beam patterns. Shaped beam patterns can be obtained by appropriately determining the complex transmission coefficient required for each cell (or element) of the printed lens, taking into account the varying feed field over the input surface of the lens. Certain ranges of transmission coefficient amplitude and phase are undesirable (eg. too low an amplitude implies a large reflection at the lens input surface). It would be preferable to constrain the range of values that the transmission coefficient can take as an integral part of the lens synthesis procedure, and thus the transmission coefficient itself needs to be the synthesis variable. In this thesis a synthesis technique for doing this is developed based on the method of generalized projections, modified to “operate” in the space of transmission coefficients. This makes it possible to immediately perceive what influence constraints on the actual transmission coefficients have on the possible radiation pattern performance. In addition, an approach that allows one to constrain the transmission coefficient to values that must be selected from an available database of transmission coefficients is incorporated into the synthesis technique.

No / In this study, a planar 4×4 phased array including modified E-shaped radiation elements is designed and fabricated to be incorporated in a Relay Station (RS) for realizing the communication with the super-ordinate Base Station. The proposed array provides 12.4% bandwidth at the 3.5GHz frequency band and gain of 21.2dB. Moreover a beamforming module is designed and simulated, aimed to be connected to the proposed array and realizing beamforming applications. This module provides 650 MHz bandwidth around 3.5GHz frequency band and is used for proper power division and controlling the amplitude/phase of the excitation currents.

<p> The objective of this research project was to study applications of statistical unimolecular reaction theories to a simple model chemical process. Such studies are needed to test the existing theories and provide direction for their further development. T-shaped Ar3, a simple chaotic two degree of freedom system, is an excellent candidate for such study, since statistical behavior is generally associated with chaotic dynamics.</p> <p> Chemical kinetics predicts fully statistical decay curves of microcanonical population associated with one of the two equivalent arrangements of T-shaped Ar3. However numerical computations, presented here, reveal nonstatistical characteristics of microcanonical T-shaped Ar3 inversion at energies associated with strongly chaotic dynamics. Nonstatisticality is most pronounced at higher energies where internal relaxation time scales are comparable to the inversion time. At such energies, population decay curves exhibit damped oscillations about the equilibrium population. At energies just above the inversion threshold, where inversion is very slow, near statistical nonoscillatory behavior is observed. The "absorbing barrier method" of J.E. Straub and B.J. Berne [J. Chem. Phys. 83, 1138 (1985)] is shown to provide a reasonable model for observed population decays. Characteristics of corresponding gap distributions are described in terms of an adapted "delayed lifetime gap model". Analysis of the model which combines the absorbing barrier method and the adapted delayed lifetime gap model provides insight into the observation of both oscillatory and nonoscillatory population decays. Specifically, the analysis describes the observations in terms of an "underdamped" or "overdamped" harmonic oscillator, respectively.</p> / Thesis / Master of Science (MSc)

No / In this study, a planar 4×4 phased array including modified E-shaped radiation elements is designed and fabricated to be incorporated in a Relay Station (RS) for realizing the communication with the super-ordinate Base Station. The proposed array provides 12.4% bandwidth at the 3.5GHz frequency band and gain of 21.2dB. Moreover a beamforming module is designed and simulated, aimed to be connected to the proposed array and realizing beamforming applications. This module provides 650 MHz bandwidth around 3.5GHz frequency band and is used for proper power division and controlling the amplitude/phase of the excitation currents.

This research introduces parallel U-shaped assembly lines with crossover points. Crossover points are connecting points between two parallel U-shaped lines making the lines interdependent. The assembly lines can be employed to manufacture a variety of products belonging to the same product family. This is achieved by utilizing the concepts of crossover points, multi-line stations, and regular stations. The binary programming formulation presented in this research can be employed for any scenario (e.g. task times, cycle times, and the number of tasks) in the configuration that includes a crossover point. The comparison of numerical problem solutions based on the proposed heuristic approach with the traditional approach highlights the possible reduction in the quantity of workers required. The conclusion from this research is that a wider variety of products can be manufactured at the same capital expense using parallel U-shaped assembly lines with crossover points, leading to a reduction in the total number of workers. / M. S.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Shaped Offset QPSK (SOQPSK) has been shown to be nearly identical in performance to Feher-patented FQPSK, which is the Advanced Range Telemetry (ATRM) program's Tier I waveform. Multi-h CPM has been selected as the ARTM Tier II waveform, because it offers 50% better spectral efficiency than the Tier I waveform. Both the Tier I and Tier II waveforms must operate in a multipath channel in order to meet the range community's telemetry requirements. This paper presents an analytical and experimental characterization of SOQPSK and Multi-h CPM in the presence of multipath. Quantitative results are presented which demonstrate the relative robustness of the ARTM Tier I and Tier II waveforms, in channels representative of a typical range environment.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Shaped BPSK (SBPSK) and Shaped Offset QPSK (SOQPSK), as defined in various MIL standards, are widely employed on SATCOM links because they offer an attractive combination of good spectral efficiency, constant envelope characteristics, and interoperability with legacy equipments. More recently, numerous terrestrial applications of OQPSK and similar waveforms (Feher-patented FQPSK) have been proposed. The present paper describes a simple non-proprietary modification of the MIL-STD SOQPSK waveform which offers spectral containment and detection efficiency comparable to or better than FQPSK-B (Revision A1), while preserving a constant envelope characteristic and backward compatibility with existing equipment.

This paper investigates the market microstructure of the Taiwan Stock Exchange Capitalization weighted Stock Index (TX) futures contracts traded on the Taiwan Futures Exchange which quite recently switched from an electronic periodic call auction market to an electronic continuous auction market. No doubt it is a rare opportunity for us to deeply look into market quality under different trading mechanisms. Using time-stamped transaction data of trades and quotes covering the period from January 2001 to September 2002, overall behavior for all TX Futures contracts are explored first—including intraday and daily patterns in the bid-ask spreads, volume, trade size, volatility, liquidity ratio and other characteristics. Next, in order to observe whether long-term contracts and short-term contracts have different patterns, the sample is divided into two groups—quarterly expiration contract months (March, June, September, and December) and non-quarterly expiration contract months, and the intraday/daily patterns are displayed. Moreover, since TAIFEX transferred trading mechanism on July 29th 2002 from an electronic periodic call auction market to an electronic continuous auction market, intraday/daily patterns are separately illustrated and compared before and after July 29th 2002, and ANOVA F-Statistic and Kruskal-Wallis tests are also taken to provide more insights into time-varying behavior under two different kinds of market trading mechanisms. The empirical results indicate that the most active periods correspond to the TAIFEX’Ss opening five-minute interval (8:45-8:50), TSEC’Ss opening five-minute interval (9:00-9:05), and TAIFEX’S closing five-minute interval (13:40-13:45) with wide spreads and large trade sizes. In 54 five-minute intervals for the regular trading session of both TAIFEX and TSEC from 9:00 a.m. to 1:30 p.m., the behavior of spreads, volume and trade sizes mainly reveal U-shaped patterns. The average trading volume within each time interval plunges, except within the final 5 minutes closing procedure interval, after TAIFEX transferred trading mechanism from an electronic periodic call auction market to an electronic continuous auction market with wider spreads and narrower volatility, in general. Moreover, intraday patterns of the average volume under new microstructure exhibit a right angular U-shape while intraday patterns of volume under old microstructure reveal a smooth U-shape. The evidence suggests a conjecture that the transfer of market trading mechanism might result in informed traders’ altering their intraday behavior and might lessening their trading desire. Further evidence in confirmation of this statement is left to future work. / This paper investigates the market microstructure of the Taiwan Stock Exchange Capitalization weighted Stock Index (TX) futures contracts traded on the Taiwan Futures Exchange which quite recently switched from an electronic periodic call auction market to an electronic continuous auction market. No doubt it is a rare opportunity for us to deeply look into market quality under different trading mechanisms. Using time-stamped transaction data of trades and quotes covering the period from January 2001 to September 2002, overall behavior for all TX Futures contracts are explored first—including intraday and daily patterns in the bid-ask spreads, volume, trade size, volatility, liquidity ratio and other characteristics. Next, in order to observe whether long-term contracts and short-term contracts have different patterns, the sample is divided into two groups—quarterly expiration contract months (March, June, September, and December) and non-quarterly expiration contract months, and the intraday/daily patterns are displayed. Moreover, since TAIFEX transferred trading mechanism on July 29th 2002 from an electronic periodic call auction market to an electronic continuous auction market, intraday/daily patterns are separately illustrated and compared before and after July 29th 2002, and ANOVA F-Statistic and Kruskal-Wallis tests are also taken to provide more insights into time-varying behavior under two different kinds of market trading mechanisms. The empirical results indicate that the most active periods correspond to the TAIFEX’Ss opening five-minute interval (8:45-8:50), TSEC’Ss opening five-minute interval (9:00-9:05), and TAIFEX’S closing five-minute interval (13:40-13:45) with wide spreads and large trade sizes. In 54 five-minute intervals for the regular trading session of both TAIFEX and TSEC from 9:00 a.m. to 1:30 p.m., the behavior of spreads, volume and trade sizes mainly reveal U-shaped patterns. The average trading volume within each time interval plunges, except within the final 5 minutes closing procedure interval, after TAIFEX transferred trading mechanism from an electronic periodic call auction market to an electronic continuous auction market with wider spreads and narrower volatility, in general. Moreover, intraday patterns of the average volume under new microstructure exhibit a right angular U-shape while intraday patterns of volume under old microstructure reveal a smooth U-shape. The evidence suggests a conjecture that the transfer of market trading mechanism might result in informed traders’ altering their intraday behavior and might lessening their trading desire. Further evidence in confirmation of this statement is left to future work.