本研究的目的，在於檢視購併案產生後，企業的報酬是否會受到平均數復歸（Mean reversion）的影響，而逐漸回復到產業的平均報酬。並且分析主併公司與被併公司佔雙方總資產比例的高低差異，所受到的不同影響程度。 本次研究的樣本採用1987～2006年中的美國電子電機產業共77件購併案，並依照主併公司佔雙方總資產的比例不同，分成為兩個群集。將兩群集做比較分析。實證結果顯示，兩個群集均有顯著的平均數復歸現象。而主併佔雙方總資產比例較高的群集，在購併第一年即有顯著的優於產業平均報酬，而主併與被併資產相近的群集，則是於第四年開始才有顯著的績效改善。根據實證結果，我們做出以下的結論： 1.企業的報酬具有平均數復歸的特性，表現優良的公司會被他人學習，而使整體產業平均報酬逐漸提升，漸漸蠶食原先與產業平均之間的差距；相反的，表現不佳的公司亦透過學習，逐漸改善自己的績效，也使的整體產業平均報酬上升，最後雙方都將趨向產業的平均水準。 2.當研究者要分析企業遭受偶發性事件（如購併）的影響時，應當考慮平均數復歸的所帶來的效果。如果忽略了平均數復歸所帶來的效果，將會對事件產生的影響給予錯誤的解讀。 3.面對購併績效的研究時，必須移除平均數復歸的負面效果，如此才得以正確估計購併後的績效表現。且此時主併公司資產佔雙方資產比例較高者，於購併第一年就有明顯的績效改善的效果，而雙方資產相近者，則在購併成立後第四年開始才有較佳的績效表現。 / The purpose of this research is to look over the return of enterprise can receive influence from mean reversion on post-merger performance. And it analyzes the degree of influence on acquirer companies with different proportion in total assets of both acquirer and target companies. The sample of this research adopts 77 cases of electronic and electrical equipment industry of U.S.A. in 1987- 200, take according to the proportion of total assets of acquirer company in both total assets of acquirer and target company, divide into two clusters. Make comparative analysis of these two clusters. According to the empirical results, we make the following conclusions: 1.The return of enterprises has characteristic of mean reversion. Both well performed companies and worse performed companies will move toward the whole industry's average return. 2.As the researcher wants to analyze the influence of enterprises suffered from the sporadic incident (such as M&A), they should consider the phenomenon of mean reversion. Take off the negative result of the mean reversion in order to estimate correctly for the exactly performance after M&A. 3.The acquirer companies which total assets have a higher proportion in both acquirer and target companies, will have superior to industry average return apparently in first year, and the acquirer companies which total assets close to the target companies, will have apparent improvement in performances until the fourth year.

The day-of-the-week effect is a market anomaly that manifests as the cyclical behaviour of traders in the market. This market anomaly was first observed by M.F.M. Osborne (1959). The literature distinguishes between two types of cyclical effects in the market: the cyclical pattern of mean returns and the cyclical pattern of volatility in returns. This dissertation studies and reports on cyclical patterns in the South African market, seeking evidence of the existence of the day-of-the-week effect. In addition, the dissertation aims to investigate the implications of such an effect on hedge fund managers in South Africa. The phenomenon of cyclical volatility and mean returns patterns (day-of-the-week effect) in the South African All-share index returns are investigated by making use of four generalised heteroskedastic conditional autoregressive (GARCH) models. These were based on Nelson's (1991) Exponential GARCH (EGARCH) models. In order to account for the risk taken by investors in the market Engle et al's, (1987) 'in-Mean' (risk factor) effects were also incorporated into the model. To avoid the dummy variable trap, two different approaches were tested for viability in testing for the day-of- the-week effect. In the first approach, one day is omitted from the equation so as to avoid multi-colinearity in the model. The second approach allows for the restriction of the daily dummy variables where all the parameters of the daily dummy variables adds up to zero. This dissertation found evidence of a mean returns effect and a volatility effect (day-of-the- week effect) in South Africa's All-share index returns data (where Wednesdays have been omitted from the GARCH equations). This holds significant implications for hedge fund managers. as hedge funds are very sensitive to volatility patterns in the market, because of their leveraged trading activities. As a result of adverse price movements, hedge fund managers employ strict risk management processes and constantly rebalance their portfolios according to a mandate, to avoid incurring losses. This rebalancing typically involves the simultaneous opening of new positions and closing out of existing positions. Hedge fund managers run the risk of incurring losses should they rebalance their portfolios on days on which the volatility in market returns is high. This study proves the existence of the day-of-the-week effect in the South African market. These results are further confirmed by the evidence of the trading volumes of the JSE's All-share index data for the period of the study. The mean returns effect (high mean returns) and low volatility found on Thursdays, coincide with the evidence that trading volumes on the JSE on Thursdays are the highest of all the days of the week. The volatility effect on Fridays, (high volatility in returns) is similarly correlated with the evidence of the trading volumes found in the JSE's All-share index data for the period of the study. Accordingly. hedge fund managers would be advised to avoid rebalancing their portfolios on Fridays, which show evidence of high volatility patterns. Hedge fund managers are advised to rather rebalance their portfolios on Thursdays, which show evidence of high mean returns patterns, low volatility patterns and high liquidity. / Thesis (M.Com. (Risk Management))--North-West University, Potchefstroom Campus, 2006.

The emergence of closed-loop Brayton cycle power plants, such as the PBMR, resulted in the need to simulate start-up transients for industrial multi-stage axial flow compressors operating at subsonic conditions. This implies that the delivery pressure and power requirements must be predicted for different mass flow rates and rotational speeds while operating in the first and fourth quadrants on the compressor performance charts. Therefore, an analytical performance prediction model for subsonic multi-stage axial flow compressors had to be developed that can be integrated into a generic network analysis software code such as Flownex. For this purpose, performance calculations based on one-dimensional mean-line analysis demonstrated good accuracy, provided that the correct models for losses, incidence and deviation are used. Such a model is therefore the focus of this study. A preliminary analytical performance prediction code, with the capability of interchanging between different deviation and loss models is presented. Reasonably complex loss models are integrated in association with the correct incidence and deviation models in a software package called "Engineering Equation Solver" (EES). The total pressure loss calculations are based on a superposition of theoretically separable loss components that include the following: blade profile losses, secondary losses and annulus losses. The fundamental conservation equations for mass, momentum and energy for compressible "rotating pipe" flow were implemented into the performance prediction code. Performance prediction models were validated against experimental data and evaluated according to their ease of implementation. Verification was done by comparing simulation results with experimental work done by Von Backstrom. This includes a calculation to determine the uncertainty in the experimental results. Furthermore, since the conventional definition of isentropic efficiency breaks down at the boundaries of quadrants on the performance charts, a new non-dimensional power formulation is presented that allows for the calculation of the compressor power in all of the relevant quadrants. Good comparison was found between simulation results and measurements in the first and fourth quadrant of operation. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2007.

Cities are often warmer than their surroundings, and this can lead to more energy being used to cool buildings. This study looks at one city, London, and assesses the impact of the urban environment on the amount of energy used for air-conditioning. There are three main strands to the work. First, it was important to determine just how great the variation in air temperature is, and how this varies through time and through the urban space. Eighty measurement stations were established along radiating lines from the centre of London as far as rural areas. These measured the air temperature simultaneously at hourly intervals for over a year. Second, to support the main data acquisition, short-term tests within London looked at specific aspects of the urban environment that affect air temperature: the effects of vegetation in parks, and facade colour in streets. Third, the impact on energy use of the measured temperature variation was then determined by using simulation to model a standard building in different urban contexts. The mean heat island intensity was found to vary with distance from the centre of London, and with the local degree of urbanization at any given distance. The maximum intensity reached 8°C on occasion but was more usually 1-2°C in the daytime and 3-4°C at night. The proximity of areas of vegetation, such as parks, to a site was associated with cooler daytime temperatures. The annual cooling load for a standard building at the centre of London was found to be 25% more than at a rural site. However, at the most urban sites over-shadowing reduced the cooling load to 14% more than at a rural site. Heating load decreased towards the centre, but on balance total annual load (for heating and cooling) rose towards the centre to 8.5% more than rural use, and then reduced at the most overshadowed sites. The balance of the effect of urbanization on heating and cooling load depended on the level of internal gain in the building. This study makes a significant contribution to understanding the balance of the impact of urban environments on the energy used for cooling and heating buildings.

Technology acceptance research is a constantly developing field. The disciplines that contributed to its development are either beliefs focused or system focused. The unified theory of acceptance and use of technology (UTAUT) combined both. The current research model proposes an extension to the UTAUT that accounts for online usage behaviour. The proposed research model is tested in two countries (UK and Jordan) to investigate the viability of the unified model of technology acceptance in different boundaries as a model of individuals’ discretionary usage of Internet banking. The study also questions the roles of other determinants and moderators in this context. Results found support for the effect of the proposed extension, website quality perceptions, on usage behaviour in both countries’ models; the total effect of this extension exhibited website quality perceptions the most influential determinant of usage behaviour in both models and performance expectancy construct was second in effect. Social influence had no impact on the usage behaviour in both models, which is consistent with previous research that advocates a declining role of social influence under discretionary usage and increased experience conditions. Furthermore, the moderating role of performance expectancy previously established in TAM’s research was supported in the UTAUT model in both countries’ models. Moreover, both models reported a non-moderating effect of gender, which, is also in line with recent research findings that suggest declining gender differences under voluntary usage conditions and advanced experience. Education and income were moderators only for the UK model. Although the research findings demonstrated that both countries’ models were “configurally” similar with respect to model specifications, the models’ explanatory power for usage behaviour was dissimilar: the UK’s model explanatory power exceeded that of Jordan’s model presenting an opportunity for future research. The current research contributes to knowledge in the field of technology acceptance research. It demonstrated that website quality perceptions, as a multidimensional concept, play an important role in the online usage context. It also demonstrated that the unified model of technology acceptance established in the western culture can be transferred to a non-western culture although with varying degrees of explanation power.

The methods of statistical physics are increasingly being employed in a range of interdisciplinary areas. In particular, aspects of complex biological processes have been elucidated by bringing the problems down to the level of simple interactions studied in a statistical sense. In nonequilibrium statistical physics, a one dimensional lattice model known as the totally asymmetric simple exclusion processes (TASEP) has become prominent as a tool for modelling various cellular transport processes. Indeed the context in which the TASEP was first introduced (MacDonald et. al., 1968) was to model ribosome motion along mRNA during protein synthesis. In this work I study a variation of the TASEP in which particles hop along a one dimensional lattice which extends as they reach the end. We introduce this model to describe the unique growth dynamics of filamentous fungi, whereby a narrow fungal filament extends purely from its tip region while being supplied with growth materials from behind the tip. We find that the steady state behaviour of our model reflects that of the TASEP, however there is an additional phase where a dynamic shock is present in the system. I show through Monte Carlo simulation and theoretical analysis that the qualitative behaviour of this model can be predicted with a simple mean-field approximation, while the details of the phase behaviour are accurate only in a refined approximation which takes into account some correlations. I also discuss a further refined mean-field approximation and give a heuristic argument for our results. Next I present an extension of the model which allows the particles to interact with a second lattice, on which they diffuse in either direction. A first order meanfield continuum approximation suggests that the steady states of this system will exhibit some novel behaviour. Through Monte Carlo simulation I discuss the qualitative changes that arise due to the on-off dynamics. Finally I study a model for a second biological phenomenon: the length fluctuations of microtubules. The model describes stochastic polymerisation events at the tip of a microtubule. Using a mean-field theory, we find a transition between regimes where the microtubule grows on average, and where the length remains finite. For low rates of polymerisation and depolymerisation, the transition is in good agreement with Monte Carlo simulation.

No description available.

Very long and noisy sequence data arise from biological sciences to social science including high throughput data in genomics and stock prices in econometrics. Often such data are collected in order to identify and understand shifts in trends, for example, from a bull market to a bear market in finance or from a normal number of chromosome copies to an excessive number of chromosome copies in genetics. Thus, identifying multiple change points in a long, possibly very long, sequence is an important problem. In this article, we review both classical and new multiple change-point detection strategies. Considering the long history and the extensive literature on the change-point detection, we provide an in-depth discussion on a normal mean change-point model from aspects of regression analysis, hypothesis testing, consistency and inference. In particular, we present a strategy to gather and aggregate local information for change-point detection that has become the cornerstone of several emerging methods because of its attractiveness in both computational and theoretical properties.

One of the most central concepts in condensed matter physics is the electronic band structure. Although band theory was established more than 80 years ago, recent developments have led to new insights that are formulated in the framework of topological band theory. In this thesis a subset of topological band theory is presented, with particular focus on topological supercon- ductors and accompanying Majorana fermions. While simple models are used to introduce basic concepts, a physically more realistic model is also studied intensely in the papers. Through self- consistent tight-binding calculations it is confirmed that Majorana fermions appear in vortex cores and at wire end points when the superconductor is in the topologically non-trivial phase. Many other properties such as the topological invariant, experimental signatures in the local density of states and spectral function, unconventional and odd-frequency pairing, the precense of spin-polarized currents and spin-polarization of the Majorana fermions, and a local π-phase shift in the order parameter at magnetic impurities are also investigated.

In dieser Arbeit wurde der Frage nachgegangen, inwieweit sich die Habitatansprüche von drei Brutvogelarten, der Offenlandart Feldlerche (Alauda arvensis), der Heckenart Neuntöter (Lanius collurio) und der Waldart Schwarzspecht (Dryocopus martius), mit Landschaftsstrukturmaßen darstellen lassen, und ob sich Landschaftsstrukturmaße für die Habitatmodellierung eignen. Basis für die Berechnung der Landschaftsstrukturmaße ist ein Flächenschema des IÖR-Monitors aus dem Jahr 2013, welches aus Daten des AFIS-ALKIS-ATKIS-Modells (AAA-Modells) aufgebaut wurde. Dieses Schema bietet redundanzfreie Flächennutzungsdaten für ganz Deutschland. Da es nur flächenhafte Elemente enthielt, wurde es um gepufferte linienhafte Elemente, genauer um Hecken, Baumreihen und Feldwege ergänzt. Die Artdaten stammen aus dem Monitoring häufiger Brutvögel (MhB), ebenfalls aus dem Jahr 2013. Die Berechnungen der Landschaftsstrukturmaße wurden mittels ArcGIS-Modellen durchgeführt. Für die Feldlerche und den Schwarzspecht wurden die Landschaftsstrukturmaße Mean Shape Index (MSI), Mean Patch Size (MPS), Anteil geeigneter Habitate (Percentage of Landscape, PLand), Total Core Area (TCA), Fläche geeigneter Biotope ohne anthropogene Störeinflüsse (Fl_ungest) und die Kantendichte der Landschaft (Edge Density, ED) berechnet. Für den Neuntöter sind es MSI, MPS, PLand, Fl_ungest, die Kantendichte und die Fläche geeigneter Gehölzbiotope und Hecken. Es wurde aufgezeigt, dass teilweise höchst signifikante lineare Zusammenhänge zwischen dem Vorkommen der drei Arten und den Landschaftsstrukturmaßen existieren. Die damit erklärten Streuungen der Brutpaarzahlen sind allerdings relativ gering. Das Bestimmtheitsmaß B oder R² der Regressionsgeraden beträgt für die Feldlerche maximal 0,285 bei der Fläche ungestörter Habitate, für den Schwarzspecht maximal 0,332 bei dem Anteil geeigneter Habitate und beim Neuntöter lediglich 0,038, ebenfalls für die Fläche ungestörter Habitate. Der Grund hierfür ist, dass die Arten Ansprüche an die Habitate stellen, die sich nicht mit Landschaftsstrukturmaßen erklären lassen. Die Modelle der multiplen linearen Regression sind ungeeignet, um Brutpaarzahlen der Arten vorherzusagen. Ohnehin war es nur für die Feldlerche möglich, ein solches Modell zu erstellen, das höhere Bestimmtheitsmaße aufweist als die einzelnen Landschaftsstrukturmaße. Deutlich bessere Ergebnisse wurden mit einem Modell erzielt, das die Eignung der Landschaft und ihrer Struktur als Habitat anhand einer Bewertungsmatrix beurteilt. Hier wurde bestimmt, wie hoch der Anteil besetzter Untersuchungsflächen an der Gesamtzahl von Untersuchungsflächen einer bestimmten Gesamtpunktzahl ist. Die Zusammenhänge zwischen Punktzahl und Anteil besetzter Flächen wurde mit teils nichtlinearen Regressionsfunktionen dargestellt. Der Anteil erklärter Abweichungen (R²) beträgt bei der Funktion der Feldlerche 97,1%, der des Schwarzspechts 88,5% und der des Neuntö-ters 49,3%.