Cloud computing allows users to tap into a massive pool of shared computing resources such as servers, storage, and network. These resources are provided as a service to the users allowing them to “plug into the cloud” similar to a utility grid. The promise of the cloud is to free users from the tedious and often complex task of managing and provisioning computing resources to run applications. At the same time, the cloud brings several additional benefits including: a pay-as-you-go cost model, easier deployment of applications, elastic scalability, high availability, and a more robust and secure infrastructure. One important class of applications that users are increasingly deploying in the cloud is database management systems. Database management systems differ from other types of applications in that they manage large amounts of state that is frequently updated, and that must be kept consistent at all scales and in the presence of failure. This makes it difficult to provide scalability and high availability for database systems in the cloud. In this thesis, we show how we can exploit cloud technologies and relational database systems to provide a highly available and scalable database service in the cloud. The first part of the thesis presents RemusDB, a reliable, cost-effective high availability solution that is implemented as a service provided by the virtualization platform. RemusDB can make any database system highly available with little or no code modifications by exploiting the capabilities of virtualization. In the second part of the thesis, we present two systems that aim to provide elastic scalability for database systems in the cloud using two very different approaches. The three systems presented in this thesis bring us closer to the goal of building a scalable and reliable transactional database service in the cloud.

We give a review of classical and recent results on maximization of expected utility for an investor who has the possibility of trading in a financial market. Emphasis will be given to the duality theory related to this convex optimization problem. For expository reasons we first consider the classical case where the underlying probability space is finite. This setting has the advantage that the technical diffculties of the proofs are reduced to a minimum, which allows for a clearer insight into the basic ideas, in particular the crucial role played by the Legendre-transform. In this setting we state and prove an existence and uniqueness theorem for the optimal investment strategy, and its relation to the dual problem; the latter consists in finding an equivalent martingale measure optimal with respect to the conjugate of the utility function. We also discuss economic interpretations of these theorems. We then pass to the general case of an arbitrage-free financial market modeled by an R^d-valued semi-martingale. In this case some regularity conditions have to be imposed in order to obtain an existence result for the primal problem of finding the optimal investment, as well as for a proper duality theory. It turns out that one may give a necessary and sufficient condition, namely a mild condition on the asymptotic behavior of the utility function, its so-called reasonable asymptotic elasticity. This property allows for an economic interpretation motivating the term "reasonable". The remarkable fact is that this regularity condition only pertains to the behavior of the utility function, while we do not have to impose any regularity conditions on the stochastic process modeling the financial market (to be precise: of course, we have to require the arbitrage-freeness of this process in a proper sense; also we have to assume in one of the cases considered below that this process is locally bounded; but otherwise it may be an arbitrary R^d-valued semi-martingale). (author's abstract) / Series: Report Series SFB "Adaptive Information Systems and Modelling in Economics and Management Science"

In this paper, we test one of the fundamental assumptions in the tax competition literature, namely, that a country's taxable income depends on the tax policies pursued in the domestic and in neighbouring countries. Based on a panel of annual data of 14 western European countries spanning the period 1982 to 2004, we show that the common trend in falling corporate income tax (CIT) rates can in part be explained by the existence of fiscal externalities in the form of international resource flows. Our results confirm the presumption put forward in recent empirical tax reaction function studies, that interdependent tax setting behaviour is evidence of tax competition. However, taxable corporate income is shown to react inelastically to domestic and to foreign tax rates. Thus, the observed rise in CIT revenues in Europe between 1982 and 2004 cannot be explained by the trend in falling CIT rates. Moreover, we find that large countries' tax bases are more responsive to neighbouring countries' tax policies, which is in contrast to the classic asymmetric tax competition literature. (author´s abstract) / Series: Discussion Papers SFB International Tax Coordination

Percutaneous transluminal balloon angioplasty followed by drug-eluting stent implantation has been of great benefit in coronary applications, whereas in peripheral applications, success rates remain low. Analysis of healing patterns in successful deployments shows that six months after implantation the artery has reorganized itself to accommodate the increase in caliber and there is no purpose for the stent to remain, potentially provoking inflammation and foreign body reaction. Thus, a fully biodegradable polymeric stent that fulfills the mission and steps away is of great benefit. Biodegradable polymers have a widespread usage in the biomedical field, such as sutures, scaffolds and implants. Degradation refers to bond scission process that breaks polymeric chains down to oligomers and monomers. Extensive degradation leads to erosion, which is the process of mass loss from the polymer bulk. The prevailing mechanism of biodegradation of aliphatic polyesters (the main class of biodegradable polymers used in biomedical applications) is random scission by passive hydrolysis and results in molecular weight reduction and softening. In order to understand the applicability and efficacy of biodegradable polymers, a two pronged approach involving experiments and theory is necessary. A constitutive model involving degradation and its impact on mechanical properties was developed through an extension of a material which response depends on the history of the motion and on a scalar parameter reflecting the local extent of degradation and depreciates the mechanical properties. A rate equation describing the chain scission process confers characteristics of stress relaxation, creep and hysteresis to the material, arising due to the entropy-producing nature of degradation and markedly different from their viscoelastic counterparts. Several initial and boundary value problems such as inflation and extension of cylinders were solved and the impacts of the constitutive model analyzed. In vitro degradation of poly(L-lactic acid) fibers under tensile load was performed and degradation and reduction in mechanical properties was dependent on the mechanical environment. Mechanical testing of degraded fibers allowed the proper choice of constitutive model and its evolution. Analysis of real stent geometries was made possible with the constitutive model integration into finite element setting and stent deformation patterns in response to pressurization changed dramatically as degradation proceeded.

Most of the surfaces have roughness down to atomic scales. When two surfaces come into contact, the nature of the roughness determines the properties like friction and wear. Analysis of the rough surface contacts is always complicated by the interaction between the material size effects and the micro-geometry. Contact mechanics could be simplified by decoupling these two effects by magnifying the scale of roughness profile. Also, tailoring the roughness at different scale could show a way to control the friction and wear through surface micro-structure modifications. In this work, the mechanics of contact between a rigid, hard sphere and a surface with a well defined roughness profile is studied through experiments and finite element simulation. The well defined roughness profile is made up of a regular array of pyramidal asperities. This choice of this geometry was mainly dictated by the fabrication processes. The specimens were made out of an aluminium alloy (6351-T6) such that there could be a direct application of the results in controlling the tribological properties during aluminium forming. Experiments on the pyramidal aluminium surface is carried out in a 250 kN Universal Testing Machine (INSTRON 8502 system) using a depth sensing indentation setup. A strain gauge based load cell is used to measure the force of the indentation and a LVDT (Linear Variable Differential Transformer) is used to measure the penetration depth. The load and the displacement were continuously recorded using a data acquisition system. A 3-D finite element framework for studying the elastic-plastic contact of the rough surfaces has been developed with the commercial package (ABAQUS). Systematic studies of indentation were carried out in order to validate the simulations with the experimental observations. The simulation of indentation of flat surface is carried out using the implicit/standard (Backward Euler) procedure, whereas, the explicit finite element method (Forward Euler) is used for simulating rough surface indentation. It is found that the load versus displacement curves obtained from experiments match well with the finite element results (except for the error involved in determining the initial contact point). At indentation depths higher than a value that is determined mainly by the asperity height, the load-displacement characteristics are similar to that pertaining to indentation of a flat, smooth surface. From the finite element results, it is found that at this point, the elastic-plastic boundary is more or less hemispherical as in the case of smooth surface indentation. For certain geometries, it is found that there could exist an elastic island in the sub-surface surrounded by plastically deformed material. This could have interesting applications.

<p>During the year of 2007, the world has experienced historically high oil prices both in nominal and in real terms, which has reopened discussions about energy sustainability. We therefore found it interesting to research oil dependencies and elasticities for Brazil, China, Norway, South Korea, Sweden and USA; and their possible oil consumption response to a Peak Oil phenomenon. Peak Oil in this thesis, implies that oil production will reach its climax and decline thereafter. To help draw conclusions, appropriate statistical analysis on macroeconomic variables was used as well as the modified Nerlove’s partial adjustment equation to calculate price and income elasticities both in the short and long-run. Regression results have shown that short-run price elasticities were low in all countries; in addition income elasticities were also inelastic but more elastic in relation to oil price elasticities. This indicates that oil consumption is more sensitive to changes in income than to changes in oil price. It was concluded that oil dependencies among nations differ and the trend is that developing countries are increasing their oil dependency while developed countries tend to decrease their oil dependency over time. Peak Oil will lead to higher oil prices, which in the short-run will change developing countries oil consumption to a greater extent than developed countries, but in the long-run their response are more similar. It was also noticed, that when GDP decreases in net-oil-importing countries, oil consumption will decrease even further. The opposite could be true for net-oil-exporting countries like Norway and Brazil.</p> / <p>Under år 2007 har världen upplevt historiskt höga oljepriser, både i nominella och reala termer, vilket återigen har lyft upp energiförsörjningen på agendan. Vi fann det därför intressant att undersöka oljeberoenden i Brasilien, Kina, Norge, Sydkorea, Sverige, USA och se hur dessa länders oljekonsumption kan påverkas av Peak Oil. Peak oil betyder att oljeproduktionen når sitt maximum och minskar därefter. För att kunna dra slutsatser har lämpliga statistiska verktyg använts på olika makroekonomiska variabler och applicerat ”Nerlove’s partial adjustment model” på data har pris-och inkomstelasticiteten av olja i varje land både på kort och lång sikt kunnat utvinnas. Från regressionen har framträtt; priselasticiteten var låg på kort sikt i alla länder och detta gäller även för inkomstelasticiteten, dock var inkomstelasticiteten relativt mer elastisk i alla länder. Detta indikerar att oljekonsumtionen är mer känslig för förändringar i inkomst än för förändringar i pris. Slutsatsen från studien är att olika länder har olika nivåer av oljeberoende och att utvecklingsländer tenderar att öka sitt relativa oljeberoende över tid medan de industrialiserade länderna tenderar att minska sitt relativa oljeberoende över tid. Peak Oil leder till högre oljepriser vilket på kort sikt kommer att påverka utvecklingsländernas oljekonsumtion mer än de industrialiserade ländernas, dock minskar skillnaden på lång sikt. En observering från denna forskning är att när BNP minskar hos olje-importörerna kommer även oljekonsumtionen att minska. För oljeexportörer som Brasilien och Norge kan oljekonsumptionen öka när BNP inkomsterna ökar från Peak Oil.</p>

<p><strong>As the public becomes more concerned with the natural environment, one of the major topics discussed is the oil. Since there is no true source of knowledge how long the oil can continue to be extracted, it is interesting to know how long the world can benefit from such as scarce resource. Instead of idly watching as oil production decreases with time, which pre-measures could be taken in order to minimize a negative impact on an economy? The UAE is a thriving oil rich countries which for the past 30 years have experienced a vast oil wealth. Even though the oil gave wealth to the UAE, they should avoid any future oil dependency since it could negatively affect its now flourishing economy. Therefore, for the UAE to continue growing in the future it is in the best interest for the government to focus on a diversifying strategy that promotes the non-oil economy. By referring to concepts and theories of previous research in this field such as the Solow growth model, Resource curse and Dutch disease the authors find that the UAE had managed to diversify or not. Three sectors in different periods between 1970 and 2007 were measured: The oil sector, the non-oil sector and the government sector. Diversification changes means a decreasing dependency of the oil sector to the non-oil sector while the latter instead depends more on the government sector. Using British Petroleum (2008) and United Nations (2008) as sources, data was collected in order to draw a time-series regression analysis and test empirically for these diversification trends. The results for all periods confirmed that the UAE have indeed diversified and it could thus be observed that it started its successful strategy already in the 1970s. With the right government policy investments and the stability in the union, the UAE prevented from becoming dependent on oil and thereby not crowding out its important non-oil economy. </strong></p> / <p><strong>Med en ökad allmän medvetenhet angående naturmiljön så är oljan bland det mest omtalande temat. Eftersom inget vet exakt hur länge oljan kan utvinnas, är det intressant att veta hur länge världen kan förlita sig på en sådan begränsad resurs. Finns det förebyggande medel för att minska en negativ verkan på ekonomin istället för att passivt bevittna en sjunkande oljeproduktion? Förenta Arabemiraten (FAE) är en framgångsrik union som under de senaste 30 åren har åtnjutit en omfattande oljerikedom. Trots att oljan lade grunden för tillväxten i FAE, så börs unionen undvika sitt oljeberoende eftersom den negativt kan påverka den nuvarande blomstrande ekonomin. Således, för att bibehålla tillväxten i FAE för framtiden, borde det vara i statens största intresse att fokusera på en differentierings-strategi som främjar icke-oljans ekonomi. För att veta om FAE faktiskt har differentierat sig eller inte, används koncept och teorier för tidigare forskning kring områdets som t.ex. Solows tillväxtmodel, Resursförbannelsen och holländska sjukan. Tre sektorer mättes i olika perioder mellan 1970-2007: oljesektorn, icke-sektorn och statssektorn. Icke-olje sektorn förväntas minska oljeberoendet samt öka beroendet av statssektorn vilket resulterar i en differentieringstrend i ekonomin. Genom källor från British Petroleum (2008) och Förenta Nationerna (2008)  har data insamlats för att empiriskt testa en tidsserie regression och se förändringar mellan sektorerna. Under alla perioder i FAE blev en differentieringstrend bekräftad och man kunde därför se att denna framgångsrika strategi redan åtogs i 1970-talet. Med effektiva investeringar i den offentliga sektorn samt en hållbar stabilitet i unionen, undvek FAE ett oljeberoende och därmed främjade icke-olje ekonomin.</strong><strong></strong></p>

The DNA contained in every living cell not only stores the genetic information; it functions in a complex molecular network that can condense, transcribe, replicate and repair genes. The essential role played by the sequence dependent structure and deformability of DNA in these basic processes of life, has received increasing attention over the past years. The present work aims at better understanding sequence dependent elasticity of double stranded DNA elasticity, across biologically relevant length scales. A theoretical description is developed that makes is possible to relate structural, biochemical and biophysical experiments and simulation. It is based on the rigid base–pair chain (rbc) model which captures all basic deformation modes on the scale of individual base–pair (bp) steps. Existing microscopic parametrizations of the rbc model rely on indirect methods. A way to relate them to biochemical experiments is provided by the indirect readout mechanism, where DNA elasticity determines protein–DNA complexation affinities. By correlating theoretical affinity predictions with in vitro measurements in a well–studied test case, different parameter sets were evaluated. As a result a new, hybrid parameter set is proposed which greatly reduces prediction errors. Indirect readout occurs mostly at particular binding subsites in a complex. A statistical marker is developed which localizes indirect readout subsites, by detecting elastically optimized sub-sequences. By a systematic coarse–graining of the rbc to the well–characterized worm–like chain (wlc) model, a quantitative connection between microscopic and kbp scale elasticity is established. The general helical rbc geometry is mapped to an effective, linear ‘on-axis’ version, yielding the full set of wlc elastic parameters for any given sequence repeat. In the random sequence case, structural variability adds conformational fluctuations which are correlated by sequence continuity. The sequence disorder correction to entropic elasticity in the rbc model is shown to coincide with the conformational correction. The results show remarkable overall agree- ment of the coarse–grained with the mesoscale wlc parameters, lending support to the model and to the microscopic parameter sets. A continuum version of the rbc is formulated as Brownian motion on the rigid motion group. Analytic expressions for angular correlation functions and moments of the end–to–end distance distribution are given. In an equivalent Lagrangian approach, conserved quantities along, and the linear response around, a general equilibrium shape are explored. / Die in jeder lebenden Zelle enthaltene DNS speichert nicht nur die genetische Information; Sie funktioniert innerhalb eines komplexen molekularen Netzwerks, das in der Lage ist, Gene zu kondensieren, transkribieren, replizieren und reparieren. Die zentrale Rolle, welche der sequenzabhängigen Struktur und Deformierbarkeit von DNS in diesen grundlegenden Lebensprozessen zukommt, erregte in den letzten Jahren zunehmendes Interesse. Die vorliegende Arbeit hat ein besseres Verständnis der sequenzabhängigen elastischen Eigenschaften von DNS auf biologisch relevanten Längenskalen zum Ziel. Es wird eine theoretische Beschreibung entwickelt, die es ermöglicht, strukturbiologische, biochemische und biophysikalische Experimente und Simulationen in Beziehung zu setzen. Diese baut auf dem Modell einer Kette aus starren Basenpaaren (rbc) auf, das alle wichtigen Deformationsmoden von DNS auf der Ebene von einzelnen Basenpaar (bp)–Schritten abbildet. Bestehende Parametersätze des rbc-Modells beruhen auf indirekten Methoden. Eine direkte Beziehung zu biochemischen Experimenten kann mithilfe des indirekten Auslese-Mechanismus hergestellt werden. Hierbei bestimmt die DNS– Elastizität Komplexierungsaffinitäten von Protein–DNS–Komplexen. Durch eine Korrelation von theoretischen Vorhersagen mit in vitro Messungen in einem gut untersuchten Beispielfall werden verschiedene Parametersätze bewertet. Als Resultat wird ein neuer Hybrid–Parametersatz vorgeschlagen, der die Vorhersagefehler stark reduziert. Indirektes Auslesen tritt meistens an speziellen Teilbindungsstellen innerhalb eines Komplexes auf. Es wird eine statistische Kenngröße entwickelt, die indirektes Auslesen durch Detektion elastisch optimierter Subsequenzen erkennt. Durch ein systematisches Coarse–Graining des rbc-Modells auf das gut charakterisierte Modell der wurmartigen Kette (wlc) wird eine quantitative Beziehung zwischen der mikroskopischen und der Elastizität auf einer kbp-Skala hergestellt. Die allgemeine helikale Geometrie wird auf eine effektive, lineare Version der Kette ‘auf der Achse’ abgebildet. Dies führt zur Berechnung des vollen Satzes von wlc-elastischen Parameters für eine beliebig vorgegebene periodische Sequenz. Im Fall zufälliger Sequenz führt die Strukturvariabilität zu zusätzlichen Konformationsfluktuationen, die durch die Kontinuität der Sequenz kurzreichweitig korreliert sind. Es wird gezeigt, daß die Sequenzunordnungs-Korrektur zur entropischen Elastizität im rbc-Modell identisch ist zur Korrektur der Konformationsstatistik. Die Ergebnisse zeigen eine bemerkenswerte Übereinstimmung der hochskalierten mikroskopischen mit den mesoskopischen wlc-Parameter und bestätigen so die Wahl des Modells und seiner mikroskopischen Parametrisierung. Eine Kontinuumsversion des rbc-Modells wird formuliert als Brownsche Bewegung auf der Gruppe der Starrkörpertransformationen. Analytische Ausdrücke für Winkelkorrelationsfunktionen und Momente der Verteilung des End-zu-End–Vektors werden angegeben. In einem äquivalenten Lagrange-Formalismus werden Erhaltungsgrößen entlang von Gleichgewichtskonformationen und die lineare Antwort in ihrer Umgebung untersucht.

關於Merton (1969) 最適投資組合策略問題，所考慮之投資情境為：一個將其財富資金安排配置於風險性資產(各類證券)與無風險短期現金部位之投資人，在給定此投資人心目中財富效用函數之前提下，希望事先決定出投資組合之最適投資權重(策略)，藉此達成在投資期滿時極大化財富效用之期望值。基於Merton (1974) 公司價值觀點，具有違約風險之證券(公司債與股票)乃是公司價值之衍生性商品，無法以傳統資產配置對股票與債券部位採取現貨方式處理最適投資策略，在此必需同時結合財務工程處理衍生性金融商品計價與避險之技術來解決。本研究利用Kron & Kraft (2003) 彈性求解法來針對市場是否有投資限制、債券提前違約、到期違約及利率隨機與否等假設，基於不同投資組合情境分析來最適投資部位策略。本研貢獻和究創新突破之處在於特別探討公司違約時，債券投資人不再享有全部公司殘值之求償權，此時股東亦享有部份比例之求償權，違約後之公司殘值將由債券投資人與股東兩者比例共分之特殊情境下，對數型態財富效用之投資人對於提前違約風險之接受度高於到期違約風險，若一般情境(股東無任何求償權)則為相反。此外亦特別提供最適成長投資組合之動態避險策略封閉解，藉以提供投資人面臨企業違約風險時應制定之投資決策與動態調整，使本研究臻至週延與實用。 / Under the Merton (1969) optimal portfolio problem, we only consider the specific investor, whose wealth utility follows the type of logarithm function; wants to maximize the expected value of the terminal wealth utility through determine the optimal investment strategy in advance. He divides his wealth into the riskless asset and risky assets such as the money market account and the various-risky securities issued by the corporate. Based on the Merton firm value framework (1974), the defaultable securities, such as the corporate bonds and stocks, are the derivatives instruments of the firm value. It will be inappropriate if we deal with this optimal portfolio problem under the original methods. Therefore, we need to handle this optimal asset allocation problem through the pricing, valuation and hedging techniques from the financial engineering simultaneously. This study apply the elasticity approach to portfolio optimization (EAPO, Kraft ,2003) to solve the optimal portfolio strategy under various scenarios, such as the market contains the investment constrain or not, intermediate default risks, mature default risk, interest rate risky under the stochastic process. The innovation and contribution of this paper are especially breaking the common setting and analysis the optimal-growth-portfolio strategy under the special scenario. In the common setting, as soon as the default event occurs, the residual firm value will be claimed by the corporate bondholders with fully proportion and the stockholder cannot share any residual value. Oppositely, the stockholder will be able to share the residual firm value proportionally with the corporate bondholder together under the so-called special scenario. We found that the investor would have higher acceptance of the premature default risk than the mature default risk in the special scenario. This phenomenon will be reversed under the common scenario. Furthermore, in order to make this study more completely and useful, we do not only illustrate the optimal investment strategy but also provide the closed-formed solution of the dynamic hedge strategy of the risky position, composed by the defaultable securities. This could help the optimal-growth-portfolio-oriented investor to make investment decision while they face the firm value downward decreasing.

This dissertation is an empirical study of demand and supply in differentiated products markets using supermarket scanner data on two particular product categories - canned tuna and hot-breakfast cereals. First, I study the impact of retailers' price promotions on consumer demand and retailer profits in the canned-tuna product category. Since canned tuna is storable, I examine whether consumers stock up during sales. The results suggest that only a limited amount of stockpiling exists in this product category. Since inventory is not very important, consumer demand is thus modeled by a static demand model with a random-coefficients-nested-logit specification, which is estimated by the Markov Chain Monte Carlo method. The unit-sales decomposition results show that on average 36% of the demand response to price promotions comes from brand-switching, so market expansion effects due to consumers switching from the outside good and to higher quantities usually dominate the brand-switching effect. Using the demand estimates, I compute optimal retail prices assuming that stores are local monopolists and choose prices to maximize static category-level profits. I find that regular prices at "high-low" stores are typically at or slightly below the optimal prices, but that regular prices at "every-day-low-price" stores are substantially below the optimal prices. These results suggest that retail price levels and price promotions are more likely related to local market conditions such as retail competition. In addition, I study the effects of store-brand (SB) entry on the demand elasticities of incumbent national brands (NB), consumers' substitution patterns for national and store brands, and the implications for consumer welfare in the hot-breakfast-cereals product category. A random-coefficients model of consumer demand is estimated by the generalized-method-of-moments approach. The empirical findings are: (1) After the entry of SB's, demand becomes more elastic for non-imitated NB's, and either more elastic or shows no change for imitated NB's; (2) in general, substitution patterns for NB's and SB's are asymmetric, i.e., when the prices of their favorite products increase, most NB buyers tend to substitute to other NB products, but SB buyers will substitute to the corresponding imitated NB's; (3) the increase in consumer surplus due to SB entry is trivial for an individual consumer, but the aggregate benefit could be quite substantial.