Each organ of a multicellular organism is unique at the level of its tissues and cells. Furthermore, responses to environmental stimuli or developmental signals occur differentially at the single cell or tissue level. This underlines the necessity of precise investigation of the “building block of life” -the individual cell. Although recently large amount of data concerning different aspects of single cell performance was accumulated, our knowledge about development and differentiation of individual cell within specialized tissue are still far from being complete. To get more insight into processes that occur in certain individual cell during its development and differentiation changes in gene expression during life cycle of A. thaliana leaf hair cell (trichome) were explored in this work. After onset of trichome development this cell changes its cell cycle: it starts endoreduplication (a modified cell cycle in which DNA replication continues in the absence of mitosis and cytokinesis). This makes trichomes a suitable model for studying cell cycle regulation, regulation of cell development and differentiation. Cells of interest were sampled by puncturing them with glass microcapillaries. Each sample contained as few as ten single cells. At first time trichomes in initial stage of trichome development were investigated. To allow their sampling they were specifically labelled by green fluorescent protein (GFP). In total three cell types were explored: pavement cells, trichome initials and mature trichomes. Comparison of gene expression profiles of these cells allowed identification of the genes differentially expressed in subsequent stages of trichome development. Bioinformatic analysis of genes preferentially expressed in trichome initials showed their involvement in hormonal, metal, sulphur response and cell-cycle regulation. Expression pattern of three selected candidate genes, involved in hormonal response and early developmental processes was confirmed by independent method. Effects of mutations in these genes on both trichome and plant development as well as on plant metabolism were analysed. As an outcome of this work novel components in the sophisticated machinery of trichome development and cell cycle progression were identified. These factors could integrate hormone stimuli and network interactions between characterized and as yet unknown members of this machinery. I expect findings presented in this work to enhance and complement our current knowledge about cell cycle progression and trichome development, as well as about performance of the individual cell in general. / Jedes Organ eines vielzelligen Organismus weißt einzigartige Merkmale auf seiner Gewebe und Zellebene auf. Darüber hinaus, werden entwicklungsabhängige sowie aus der Umwelt empfangene Signale zelltypspezifisch interpretiert. Aus dieser Spezialisierung einzelner Zellen ergibt sich somit unmittelbar die Notwendigkeit einzelne Zellen, als Bausteine komplexer Organe, individuell zu untersuchen. Obwohl in den letzten Jahrzehnten große Datenmengen über verschiedene Aspekte einzelner Zellen akkumuliert wurden, ist das Gesamtbild der Differenzierung und Entwicklung individueller Zellen in einem vielzelligen Organismus weitgehend unbekannt. Um der Frage nachzugehen, welche Prozesse sich in einer einzelnen Zelle während ihrer Differenzierung und Entwicklung abspielen, wurden Genexpressionsprofile einzelner Blatthaarzellen der Pflanze Arabidopsis thaliana in verschiedene Entwicklungsstadien erstellt. Nach dem Beginn der Entwicklung einer Protodermalzelle in ein Blatthaar (Trichom) kommt es zu einem Umschalten des Zellzyklus; Endoreduplikation setzt ein. Dies bedeutet, dass DNA repliziert wird, aber keine Zellteilung mehr stattfindet. Aus diesem Grunde eignen sich heranwachsende Trichome besonders gut Mechanismen zu erforschen, die in Verbindung mit der Zellzyklusregulation und Zellentwicklung stehen. Die Inhalte ausgewählter Einzelzellen wurden mit Glasmikrokapillaren extrahiert. Jeweils zehn derartige Einzelzellextrakte wurden daraufhin vereint. Als besonders hervorzuheben gilt, dass es uns in dieser Studie zum ersten mal überhaupt gelang die Inhalte einzelner Trichomzellen in ganz frühen Entwicklungsstadien zu extrahieren und anschließend zu analysieren. Um die Extraktion der Inhalte dieser frühen Zellstadien überhaupt zu ermöglichen, war es erforderlich diese mit dem grün fluoreszierenden Protein (GFP) zu markieren. Neben den Trichominitialzellen wurden ausgewachsene Trichomzellen sowie Epidermiszellen (Pavementzellen) mittels der Einzelzelltechnik untersucht. Ein Vergleich der erstellten Genexpressionsprofile dieser drei Zelltypen ermöglichte es Gene zu identifizieren, die in den ausgewählten Entwicklungsstadien der Trichombildung differentiell induziert wurden. Mittels bioinformatischer Analysemethoden gelang es, Gruppen von Genen zu identifieren, die exklusiv in Trichominitialzellen exprimiert sind und den Kategorien, Hormonregulation, Metallhomeostase, Schwefelstoffwechesol sowie Zellzyklusregulation zuzuordnen sind. Weiterhin wurde das Expressionsmuster dreier ausgewählter Kandidatengene mit alternativen Techniken verifiziert. Die ausgewählten Kandidatengene gehörten den Katergorien, Hormonrespons sowie frühe Entwicklungsprozesse, an. Darüber hinaus wurden Mutanten in allen drei Gene erzeugt und der Einfluss dieser Mutationen auf die Trichomentwicklung analysiert. Ein weiterer Aspekt der Mutantenanalyse lag in der Erstellung von Metabolitenprofilen ausgewählter Mutanten. Als ein wesentliches Ziel dieser Arbeit gelang es mir bisher unbekannte Komponenten in der Trichomentwicklung und damit der Zellzyklusregulation zu identifizieren. Diese neu identifizierten Komponenten führen zu einer Integration der hormonellen Kontrolle der Zellteilung und Entwicklung mit bisher unbekannten Faktoren. Ich erwarte, dass die von mir erbrachten Ergebnisse zu einem tieferen Verständnis der Prozesse, die an der Trichomentwicklung sowie an der Zellzyklusregulation beteiligt sind, beitragen. Insbesondere, zu einem erweiterten Verständnis des Verhaltens individueller Zellen in einem vielzelligen Organismus.

IPO underpricing is a phenomenon found in all markets worldwide. Investors are always looking for a good opportunity of short-term abnormal positive returns, and the IPOs first-day trading returns have been a good investment strategy for both institutional and private investors in all markets of the world. This study consists at an investor’s perspective analysis of the first-day returns of 59 IPOs listed on the Brazilian Stock Exchange Market from January 2004 to April 2007, where I have found a significantly mean positive underpricing of 6,60%. I have found also some evidences of a sprouting “hot-market” period in Brazil, since the number of the IPOs in Brazil has been growing almost in an exponential speed, taking advantage of the constant growing cash inflow and liquidity of the Brazilian market, followed by the high evaluation of the Ibovespa Index, with return of 140% on the study time frame. When categorizing the study by year, by underwriter (investment bank) and by market segment, I always have found positive adjusted initial returns, which corroborates the fact that underpricing is a constant phenomenon in the Brazilian market. Other important facts that were identified in this study is that the average returns of the IPOs are decreasing along the years and that companies that depend to a large extent on their human capital and are in the business areas that are staff intensive have a high level of underpricing while companies that have a high level of fixed assets have a low level of underpricing. Finally, after performing a multivariate linear regression analysis with the chosen independent variables on the full sample and some categorized samples, the results did not have enough statistical significance and consistence that could make them useful to create a statistical model to explain the underpricing level of Brazilian IPOs between January 2004 and April 2007.

Bakgrund: Under de senaste två åren så har svenska Private Equity-bolag ökat sina investeringar signifikant. Enkelheten i att anskaffa kapital, såväl som billig skuldsättningsgrad har lett till en ökad aktivitet från PE-bolagen genom uppköp av marknadsledande bolag med starkt kassaflöde. Konkurrensen för attraktiva företag som är till salu har ökat nämnvärt, vilket i sin tur har lett till prisökningar på de utsatta bolagen. De högre värderingarna från PE-bolagen påverkar också antalet börsintroduktioner på Stockholmsbörsen. Ett skäl för de allt färre börsintroduktioner kommer av att bolagen har blivit högre värderade av PE-bolagen jämförelsevis med en värdet av en börsintroduktion. Syfte: Avsikten med denna uppsats är att, från aktieägarens synvinkel, analysera och beskriva de olika skäl som finns för att gör en börsintroduktion istället för att sälja till ett PE-bolag. Metod: Undersökningen är baserad på att samla och förstå information gällande specifika personers val och motiv med ett kvalitativt synsätt. Urvalet från undersökningen innehåller alla företag som har genomfört en börsintroduktion på Stockholmsbörsen mellan 1 januari 2005 och 1 april 2006. Intervjuerna har genomförts med varje styrelseordförande, i och med att författarna tror att dessa företrädare är de bästa representanterna för aktieägarna. De personer som lät sig intervjuas fick tala fritt, även om de större frågorna var tvungna att följas i kronologisk ordning. Slutsats: Alla motiv för att genomföra en börsintroduktion kunde ha uppfyllts genom att sälja till ett PE-bolag, förutom motivet om att uppnå likviditet i aktierna. Ett av de attraktiva motiven för likviditet i aktier är att aktieägarna kan välja mellan att minska ägandet, öka ägandet eller bibehålla de nuvarande aktierna. Ett annat attraktivt skäl är att finansiella institutioner normalt ansluter sig som aktieägare, vilket i sin tur ökar trovärdigheten av företaget. Åtta av det tio företagen hade parallella planer längs med arbetet med börsintroduktionen. De flesta av bolagen hade i åtanke att sälja till ett PE-bolag vid eventuellt gynnsamt bud. Dock fanns det inga PE-bolag som bjöd ett tillräckligt bra pris för de individuella bolagen. Antingen så erhöll de dåvarande ägarna ett bättre pris från börsintroduktionen, eller så trodde de återstående ägarna på att börsen i framtiden skulle prestera bättre än PE-bolagens bud. Enligt teorierna har buy-outs fler fördelar jämförelsevis med börsintroduktioner, men de empiriska undersökningarna visar att de två alternativen var likvärdiga. Den enda fördelen med en eventuell buy-out var att det skulle begära mindre eller samma arbetsbelastning i termer av förberedelser. Dock så ansågs en börsintroduktion vara dyr såväl som att den tar energi och fokus från ledningen. / Background: During the last two years, Swedish Private Equity (PE) companies have increased their investments significantly. Easy access to capital, as well as inexpensive leverage, has led to an increase in activity of PE buy-outs of market leaders with strong cash flow. The competition for objects that are for sale has amplified, which has resulted in price increases of the objects. The higher prices offered by the PE companies also affects the number of initial public offerings (IPO) on the Stockholm Stock Exchange. One reason for the small number of current IPOs is that the objects simply have been valued higher by PE companies than they would do in an IPO. Purpose: The purpose with this thesis is, from a shareholder’s point of view, to analyze and describe the reasons of making an IPO instead of selling to a PE company. Methodology: Since the research is based on gathering and understanding information regarding specific persons’ choices and motives, a qualitative approach has been conducted. The research sample contains of all companies that made an IPO on the Stockholm Stock Exchange between 1 January 2005 and 1 April 2006. Interviews have been made with each company’s Chairman of the Board of Directors, since the authors believe that these individuals are the ultimate shareholder rep-resentatives. The interviewees were allowed to speak freely, even though the major questions had to be followed in a chronological order. Conclusion: All the main motives of the IPO could have been achieved by selling to PE company, except the motive of attaining share liquidity. One of the attractive reasons for share liquidity is that shareholders easily can choose between reducing ownership, increasing ownership or remain with existing shares. Another attractive reason is that financial institutions normally become share-holders, which in turn increases the credibility of the company. Eight out of the ten companies had parallel plans to the IPO; most of them including a possible PE buy-out scenario. However, no PE company offered a price high enough for the individual companies. Either the existing owners received a better IPO price, or the remaining owners believed that the stock exchange would out-perform the PE price offers in the long-run. Theory means that buy-out has got its advantages compared to IPO, but the empirical findings show that the alternatives were on the contrary quite similar. The single advantage with a possible buy-out was that it would demand less, or at most equal, work load in terms of preparation before the sale. However, the negative part with the IPO was that it was considered expensive as well as it took energy and distraction of focus it took from the management team.

Despite recent rhetoric advocating the diversification of the teacher workforce, teachers in Canada continue to be disproportionately white and of northern European heritage. By investigating responses to difference experienced by racial and linguistic minority immigrant teacher candidates in an initial teacher education program, this thesis sheds light on dynamics that challenge or support the induction of minoritized individuals as members of the teaching profession in Canada. Data collected through interviews with eight immigrant teacher candidates, four instructors, and five student support staff of an initial teacher education program at an urban Canadian university (UCU) indicated that teacher candidates at UCU experienced varied responses to difference. Influences of both hegemony and collaboration were found in the university and practice teaching contexts where individuals representing regimes of competence enacted challenging assimilationist or supportive multiculturalist ideologies. In practice teaching contexts, although all of the teacher candidates engaged with at least one collaborative mentor teacher and they all persisted to complete the program, six of the eight teacher candidates (i.e., all of the linguistic minority teacher candidates in this study) encountered a challenging and significantly discouraging relationship with a mentor teacher. In these hegemonic contexts the legitimacy of the teacher candidates appeared to be measured against a conception of “real teachers” as “real Canadians” who are native English-speakers and who are familiar with the culture of schooling in Canada. Within the university context, student support staff were consistent in their critical awareness of the challenges and supports experienced by teacher candidates while instructors demonstrated a range of familiarity with these issues and with concepts of equity as they relate to the experiences of teacher candidates. Implications of this study support the following: continuation of programs offered through student support services; educative collaborative implementation of UCU’s equity policy to promote greater consistency in its influence; application of inclusive pedagogy; greater curricular emphasis on social power and constructions of difference; recognition of immigrant teachers’ linguistic capital; development of a collaborative method to evaluate teacher candidates in practice teaching contexts; and continued effort to advance a more profound and consistent influence of multiculturalist ideology in Canadian schools.

Despite recent rhetoric advocating the diversification of the teacher workforce, teachers in Canada continue to be disproportionately white and of northern European heritage. By investigating responses to difference experienced by racial and linguistic minority immigrant teacher candidates in an initial teacher education program, this thesis sheds light on dynamics that challenge or support the induction of minoritized individuals as members of the teaching profession in Canada. Data collected through interviews with eight immigrant teacher candidates, four instructors, and five student support staff of an initial teacher education program at an urban Canadian university (UCU) indicated that teacher candidates at UCU experienced varied responses to difference. Influences of both hegemony and collaboration were found in the university and practice teaching contexts where individuals representing regimes of competence enacted challenging assimilationist or supportive multiculturalist ideologies. In practice teaching contexts, although all of the teacher candidates engaged with at least one collaborative mentor teacher and they all persisted to complete the program, six of the eight teacher candidates (i.e., all of the linguistic minority teacher candidates in this study) encountered a challenging and significantly discouraging relationship with a mentor teacher. In these hegemonic contexts the legitimacy of the teacher candidates appeared to be measured against a conception of “real teachers” as “real Canadians” who are native English-speakers and who are familiar with the culture of schooling in Canada. Within the university context, student support staff were consistent in their critical awareness of the challenges and supports experienced by teacher candidates while instructors demonstrated a range of familiarity with these issues and with concepts of equity as they relate to the experiences of teacher candidates. Implications of this study support the following: continuation of programs offered through student support services; educative collaborative implementation of UCU’s equity policy to promote greater consistency in its influence; application of inclusive pedagogy; greater curricular emphasis on social power and constructions of difference; recognition of immigrant teachers’ linguistic capital; development of a collaborative method to evaluate teacher candidates in practice teaching contexts; and continued effort to advance a more profound and consistent influence of multiculturalist ideology in Canadian schools.

An experimental study of the effect of initial conditions on the development of Rayleigh Taylor Instabilities (RTI) at low Atwood numbers (order of 10-4) was performed in the water channel facility at TAMU. Initial conditions of the flow were generated using a controllable, highly reliable Servo motor. The uniqueness of the study is the system’s capability of generating the required initial conditions precisely as compared to the previous endeavors. Backlit photography was used for imaging and ensemble averaging of the images was performed to study mixing width characteristics in different regimes of evolution of Rayleigh-Taylor Instability (RTI). High-speed imaging of the flows was performed to provide insights into the growth of bubble and spikes in the linear and non-linear regime of instability development. RTI are observed in astrophysics, geophysics and in many instances in nature. The vital role of RTI in the feasibility and efficiency of the Inertial Confinement Fusion (ICF) experiment warrants a comprehensive study of the effect of mixing characteristics of RTI and its dependence on defining parameters. With this broader objective in perspective, the objectives of this present investigation were mainly threefold: First was the validation of the novel setup of the Water channel system. Towards this objective, validation of Servo motor, splitter plate thickness effects, density and temperature measurements and single-mode experiments were performed. The second objective was to study the mixing and growth characteristics of binary and multi-mode initial perturbations seeking an explanation of behavior of the resultant flow structures by performing the first ever set of such highly controlled experiments. The first-ever set of experiments with highly controlled multi-mode initial conditions was performed. The final objective of this study was to measure and compare the bubble and spike velocities with single-mode initial conditions with existing analytical models. The data derived from these experiments would qualitatively and quantitatively enhance the understanding of dependence of mixing width on parametric initial conditions. The knowledge would contribute towards a generalized theory for RTI mixing with specified dependence on various parameters, which has a wide range of applications. The system setup was validated to provide a reliable platform for the novel multi-modal experiments to be performed in the future. It was observed that the ensemble averaged mixing width of the binary system does not vary significantly with the phase-difference between the modes of a binary mode initial condition experiment, whereas it varies with the amplitudes of the component modes. In the exponential and non-linear regimes of evolution, growth rates of multi-mode perturbations were found to be higher than the component modes, whereas saturation growth rates correspond to the dominant wavelength. Quadratic saturation growth rate constants, alpha were found to be about 0.07 ± 0.01 for binary and multi modes whereas single-mode data measured alpha about 0.06 ± 0.01. High-speed imaging was performed to measure bubble and spike amplitudes to obtain velocities and growth rates. It was concluded that higher temporal and spatial resolution was required for accurate measurement. The knowledge gained from the above study will facilitate a better understanding of the physics underlying Rayleigh-Taylor instability. The results of this study will also help validating numerical models for simulation of this instability, thereby providing predictive capability for more complex configurations.

Re-commissioning, retro-commissioning, Continuous Commissioning® (CC®) are examples of successful systematic processes implemented in buildings to reduce overall building energy consumption, and improve efficiency of systems and their operations and control. The impact of the Continuous Commissioning® Process on the Energy Star® Rating (ESR) of office buildings and hospitals is examined in this thesis. The improvement in performance of a building, and subsequently its ESR, is found to be influenced by its initial ESR, while its location has no impact on improvement. The improvement in ESR is observed to be almost linearly proportional to the percentage of energy saved. For 10% - 20% reductions in energy use typical of the CC® process, the ESR is increased by 10-19 ESR ranks for office buildings and by 13 - 26 ESR ranks for hospitals. The CC® process is found to potentially enable an office building of average initial ESR of 62 and a hospital of average initial ESR of 55, located anywhere in the US, to be eligible to achieve ESR of 75 and consequently the Energy Star recognition. The improvement of ESR is a function of the initial ESR and the building type; hence it is observed to be different for hospitals and office buildings in the study. For hospital and office building models occupying 100,000 ft² of floor area each, a difference of about 30% in the ESR improvement (greater for hospitals) is observed. The energy intensities may be different for buildings with same ESRs that have different location and/or type. An averaged maximum difference of energy intensity of approximately 10% is observed to exist for identical buildings and of the same type but located at different locations. Hospitals are observed to be more than twice as energy intensive as office buildings for the same location and equal ESRs. ESR plotted against % energy savings at site reveals the stepped nature of ESR system. At specific initial ESR and corresponding % savings a reduction of up to approximately 1% for office buildings and up to 1.5% for hospitals does not change the respective ESRs for the model set of buildings in the study.

<p>Bakgrund: Under de senaste två åren så har svenska Private Equity-bolag ökat sina investeringar signifikant. Enkelheten i att anskaffa kapital, såväl som billig skuldsättningsgrad har lett till en ökad aktivitet från PE-bolagen genom uppköp av marknadsledande bolag med starkt kassaflöde. Konkurrensen för attraktiva företag som är till salu har ökat nämnvärt, vilket i sin tur har lett till prisökningar på de utsatta bolagen. De högre värderingarna från PE-bolagen påverkar också antalet börsintroduktioner på Stockholmsbörsen. Ett skäl för de allt färre börsintroduktioner kommer av att bolagen har blivit högre värderade av PE-bolagen jämförelsevis med en värdet av en börsintroduktion.</p><p>Syfte: Avsikten med denna uppsats är att, från aktieägarens synvinkel, analysera och beskriva de olika skäl som finns för att gör en börsintroduktion istället för att sälja till ett PE-bolag.</p><p>Metod: Undersökningen är baserad på att samla och förstå information gällande specifika personers val och motiv med ett kvalitativt synsätt. Urvalet från undersökningen innehåller alla företag som har genomfört en börsintroduktion på Stockholmsbörsen mellan 1 januari 2005 och 1 april 2006. Intervjuerna har genomförts med varje styrelseordförande, i och med att författarna tror att dessa företrädare är de bästa representanterna för aktieägarna. De personer som lät sig intervjuas fick tala fritt, även om de större frågorna var tvungna att följas i kronologisk ordning.</p><p>Slutsats: Alla motiv för att genomföra en börsintroduktion kunde ha uppfyllts genom att sälja till ett PE-bolag, förutom motivet om att uppnå likviditet i aktierna. Ett av de attraktiva motiven för likviditet i aktier är att aktieägarna kan välja mellan att minska ägandet, öka ägandet eller bibehålla de nuvarande aktierna. Ett annat attraktivt skäl är att finansiella institutioner normalt ansluter sig som aktieägare, vilket i sin tur ökar trovärdigheten av företaget. Åtta av det tio företagen hade parallella planer längs med arbetet med börsintroduktionen. De flesta av bolagen hade i åtanke att sälja till ett PE-bolag vid eventuellt gynnsamt bud. Dock fanns det inga PE-bolag som bjöd ett tillräckligt bra pris för de individuella bolagen. Antingen så erhöll de dåvarande ägarna ett bättre pris från börsintroduktionen, eller så trodde de återstående ägarna på att börsen i framtiden skulle prestera bättre än PE-bolagens bud. Enligt teorierna har buy-outs fler fördelar jämförelsevis med börsintroduktioner, men de empiriska undersökningarna visar att de två alternativen var likvärdiga. Den enda fördelen med en eventuell buy-out var att det skulle begära mindre eller samma arbetsbelastning i termer av förberedelser. Dock så ansågs en börsintroduktion vara dyr såväl som att den tar energi och fokus från ledningen.</p> / <p>Background: During the last two years, Swedish Private Equity (PE) companies have increased their investments significantly. Easy access to capital, as well as inexpensive leverage, has led to an increase in activity of PE buy-outs of market leaders with strong cash flow. The competition for objects that are for sale has amplified, which has resulted in price increases of the objects. The higher prices offered by the PE companies also affects the number of initial public offerings (IPO) on the Stockholm Stock Exchange. One reason for the small number of current IPOs is that the objects simply have been valued higher by PE companies than they would do in an IPO.</p><p>Purpose: The purpose with this thesis is, from a shareholder’s point of view, to analyze and describe the reasons of making an IPO instead of selling to a PE company.</p><p>Methodology: Since the research is based on gathering and understanding information regarding specific persons’ choices and motives, a qualitative approach has been conducted. The research sample contains of all companies that made an IPO on the Stockholm Stock Exchange between 1 January 2005 and 1 April 2006. Interviews have been made with each company’s Chairman of the Board of Directors, since the authors believe that these individuals are the ultimate shareholder rep-resentatives. The interviewees were allowed to speak freely, even though the major questions had to be followed in a chronological order.</p><p>Conclusion: All the main motives of the IPO could have been achieved by selling to PE company, except the motive of attaining share liquidity. One of the attractive reasons for share liquidity is that shareholders easily can choose between reducing ownership, increasing ownership or remain with existing shares. Another attractive reason is that financial institutions normally become share-holders, which in turn increases the credibility of the company. Eight out of the ten companies had parallel plans to the IPO; most of them including a possible PE buy-out scenario. However, no PE company offered a price high enough for the individual companies. Either the existing owners received a better IPO price, or the remaining owners believed that the stock exchange would out-perform the PE price offers in the long-run. Theory means that buy-out has got its advantages compared to IPO, but the empirical findings show that the alternatives were on the contrary quite similar. The single advantage with a possible buy-out was that it would demand less, or at most equal, work load in terms of preparation before the sale. However, the negative part with the IPO was that it was considered expensive as well as it took energy and distraction of focus it took from the management team.</p>

Low relief, heavily human-impacted landscapes like those of the Prairies in south-central Canada have received little attention in previous hydrological research. Here, the rainfall-runoff relationship in the context of both a field-based investigation and an empirical model is examined in an effort to provide insight into Prairie hydrology. Rainfall and water level data were collected for nested sub-watersheds of the Catfish Creek watershed, a 642 km2, near-level, mixed land use and engineered Prairie watershed. First, the dataset is examined for runoff controls. Second, the history of the United States Curve Number Method is reviewed and its initial abstraction ratio examined against collected field data to determine the applicability of a single, constant ratio to Prairie landscapes. Overall, the results indicate that Prairie runoff generation processes differ significantly from those of humid, pristine catchments of higher relief and a conceptual model is proposed with that regards.

With the increasing advancements in the digital technology, future wireless systems are promising to support higher data rates, higher mobile speeds, and wider coverage areas, among other features. While further technological developments allow systems to support higher computational complexity, lower power consumption, and employ larger memory units, other resources remain limited. One such resource, which is of great importance to wireless systems, is the available spectrum for radio communications. To be able to support high data rate wireless applications, there is a need for larger bandwidths in the spectrum. Since the spectrum cannot be expanded, studies have been concerned with fully utilizing the available spectrum. One approach to achieve this goal is to reuse the available spectrum through space, time, frequency, and code multiplexing techniques. Another approach is to optimize the transceiver design as to achieve the highest throughput over the used spectrum. From the physical layer perspective, there is a need for a highly flexible and efficient modulation technique to carry the communication signal. A multicarrier modulation technique known as orthogonal frequency division multiplexing (OFDM) is one example of such a technique. OFDM has been used in a number of current wireless standards such as wireless fidelity (WiFi) and worldwide interoperability for microwave access (WiMAX) standards by the Institute of Electrical and Electronics Engineers (IEEE), and has been proposed for future 4G technologies such as the long term evolution (LTE) and LTE-advanced standards by the 3rd Generation Partnership Project (3GPP), and the wireless world initiative new radio (WINNER) standard by the Information society technologies (IST). This is due to OFDM’s high spectral efficiency, resistance to narrow band interference, support for high data rates, adaptivity, and scalability. In this dissertation, OFDM and multiuser OFDM , also known as orthogonal frequency division multiple access (OFDMA), techniques are investigated as a candidate for advanced wireless systems. Features and requirements of future applications are discussed in detail, and OFDM’s ability to satisfy these requirements is investigated. We identify a number of challenges that when addressed can improve the performance and throughput of OFDM-based systems. The challenges are investigated over three stages. In the first stage, minimizing, or avoiding, the interference between multiple OFDMA users as well as adjacent systems is addressed. An efficient algorithm for OFDMA uplink synchronization that maintains the orthogonality between multiple users is proposed. For adjacent channel interference, a new spectrum shaping method is proposed that can reduce the out-of-band radiation of OFDM signals. Both methods increase the utilization of available spectrum and reduce interference between different users. In the second stage, the goal is to maximize the system throughput for a given available bandwidth. The OFDM system performance is considered under practical channel conditions, and the corresponding bit error rate (BER) expressions are derived. Based on these results, the optimum pilot insertion rate is investigated. In addition, a new pilot pattern that improves the system ability to estimate and equalize various radio frequency (RF) impairments is proposed. In the last stage, acquiring reliable measurements regarding the received signal is addressed. Error vector magnitude (EVM) is a common performance metric that is being used in many of today’s standards and measurement devices. Inferring the signal-to-noise ratio (SNR) from EVM measurements has been investigated for either high SNR values or data-aided systems. We show that using current methods does not yield reliable estimates of the SNR under other conditions. Thus, we consider the relation between EVM and SNR for nondata-aided systems. We provide expressions that allow for accurate SNR estimation under various practical channel conditions.