Computer simulations of two-dimensional colloidal crystals under confinement and shear

In this thesis we are presenting a broadly based computer simulation study of two-dimensional colloidal crystals under different external conditions. In order to fully understand the phenomena which occur when the system is being compressed or when the walls are being sheared, it proved necessary to study also the basic motion of the particles and the diffusion processes which occur in the case without these external forces. In the first part of this thesis we investigate the structural transition in the number of rows which occurs when the crystal is being compressed by placing the structured walls closer together. Previous attempts to locate this transition were impeded by huge hysteresis effects. We were able to determine the transition point with higher precision by applying both the Schmid-Schilling thermodynamic integration method and the phase switch Monte Carlo method in order to determine the free energies. These simulations showed not only that the phase switch method can successfully be applied to systems with a few thousand particles and a soft crystalline structure with a superimposed pattern of defects, but also that this method is way more efficient than a thermodynamic integration when free energy differences are to be calculated. Additionally, the phase switch method enabled us to distinguish between several energetically very similar structures and to determine which one of them was actually stable. Another aspect considered in the first result chapter of this thesis is the ensemble inequivalence which can be observed when the structural transition is studied in the NpT and in the NVT ensemble. The second part of this work deals with the basic motion occurring in colloidal crystals confined by structured walls. Several cases are compared where the walls are placed in different positions, thereby introducing an incommensurability into the crystalline structure. Also the movement of the solitons, which are created in the course of the structural transition, is investigated. Furthermore, we will present results showing that not only the well-known mechanism of vacancies and interstitial particles leads to diffusion in our model system, but that also cooperative ring rotation phenomena occur. In this part and the following we applied Langevin dynamics simulations. In the last chapter of this work we will present results on the effect of shear on the colloidal crystal. The shear was implemented by moving the walls with constant velocity. We have observed shear banding and, depending on the shear velocity, that the inner part of the crystal breaks into several domains with different orientations. At very high shear velocities holes are created in the structure, which originate close to the walls, but also diffuse into the inner part of the crystal.

"Un libro per ogni compagno". Case editrici e politiche per la lettura del partito comunista italiano (1944-1956)

Anche se la politica editoriale comunista rappresenta un campo di indagine fondamentale nella ricerca sul Pci, la sua attivit�� editoriale �� caduta in un oblio storico. Assumendo il libro come supporto materiale e veicolo della cultura politica comunista, e la casa editrice come canale di socializzazione, questa ricerca s���interroga sui suoi processi di costruzione e di diffusione. La ricerca si muove in due direzioni. Nel primo capitolo si �� tentato di dare conto delle ragioni metodologiche dell���indagine e della messa a punto delle ipotesi di ricerca sul ���partito editore���, raccogliendo alcune sfide poste alla storia politica da altri ambiti disciplinari, come la sociologia e la scienza politica, che rappresentano una vena feconda per la nostra indagine. La seconda direzione, empirica, ha riguardato la ricognizione delle fonti e degli strumenti di analisi per ricostruire le vicende del ���partito editore��� dal 1944 al 1956. La suddivisione della ricerca in due parti ��� 1944-1947 e 1947-1956 ��� segue a grandi linee la periodizzazione classica individuata dalla storiografia sulla politica culturale del Pci, ed �� costruita su quattro fratture storiche ��� il 1944, con la ���svolta di Salerno���; il 1947, con la ���svolta cominformista���; il 1953, con la morte di Stalin e il disgelo; il 1956, con il XX Congresso e i fatti d���Ungheria ��� che sono risultate significative anche per la nostra ricerca sull���editoria comunista. Infine, il presente lavoro si basa su tre livelli di analisi: l���individuazione dei meccanismi di decisione politica e dell���organizzazione assunta dall���editoria comunista, esaminando gli scopi e i mutamenti organizzativi interni al partito per capire come i mutamenti strategici e tattici si sono riflessi sull���attivit�� editoriale; la ricostruzione della produzione editoriale comunista; infine, l���identificazione dei processi di distribuzione e delle politiche per la lettura promosse dal Pci.

The Feynman-Kac formula and applications to PDEs

The thesis presents a probabilistic approach to the theory of semigroups of operators, with particular attention to the Markov and Feller semigroups. The first goal of this work is the proof of the fundamental Feynman-Kac formula, which gives the solution of certain parabolic Cauchy problems, in terms of the expected value of the initial condition computed at the associated stochastic diffusion processes. The second target is the characterization of the principal eigenvalue of the generator of a semigroup with Markov transition probability function and of second order elliptic operators with real coefficients not necessarily self-adjoint. The thesis is divided into three chapters. In the first chapter we study the Brownian motion and some of its main properties, the stochastic processes, the stochastic integral and the It�� formula in order to finally arrive, in the last section, at the proof of the Feynman-Kac formula. The second chapter is devoted to the probabilistic approach to the semigroups theory and it is here that we introduce Markov and Feller semigroups. Special emphasis is given to the Feller semigroup associated with the Brownian motion. The third and last chapter is divided into two sections. In the first one we present the abstract characterization of the principal eigenvalue of the infinitesimal generator of a semigroup of operators acting on continuous functions over a compact metric space. In the second section this approach is used to study the principal eigenvalue of elliptic partial differential operators with real coefficients. At the end, in the appendix, we gather some of the technical results used in the thesis in more details. Appendix A is devoted to the Sion minimax theorem, while in appendix B we prove the Chernoff product formula for not necessarily self-adjoint operators.

Tropfenbasierte Multiphasen ��� Mikroreaktionstechnologie in organisch-chemischer Synthese

In der vorliegenden Doktorarbeit werden neue, mikrofluidische Verfahren, zur Durchf��hrung chemischer Reaktionen in mehrphasigen Systemen pr��sentiert. rnDas Einschlie��en von Reaktionspartnern in einzelne Segmente, deren Volumina im Bereich von Mikro- bis Femtoliter liegen und die dadurch erzeugten enormen, spezifischen Oberfl��chen, erm��glichen Massentransportprozesse ��ber die Phasengrenzfl��che zwischen einzelnen Segmenten, drastisch zu intensivieren. Aufgrund geringer r��umlicher Ausdehnungen einzelner Kompartimente und durch vorherrschende, zirkulierende Str��mungen in den einzelnen Abschnitten, sind Diffusions- und Konvektionsprozesse in diesen rasch, sodass an der Grenzfl��che gebildete, reaktive Intermediate in sehr kurzen Zeitintervallen umgesetzt werden k��nnen. rnrn

First results from stable-istope measurements on ice cores from Dronning Maud Land

The European Project for Ice Coring in Antarctica (EPICA) focuses on the drilling of two deep ice cores, the first at Dome C and the second at Kohnen station (75��00' S, 0��04' E) in Dronning Maud Land (DML). This paper deals with stable-isotope records from ice cores drilled in DML. In the first season, the deep EPICA DML core reached a depth of 450 m, recovering ice approximately 7000 years old. Generally, the d18O record indicates a stable Holocene climate and shows low variability. However, during the last 4000 years (based on a preliminary time-scale) the d18O values decrease continuously by about 0.6%, and the deuterium excess values increase by about 0.5%. The correlation between d18O and the deuterium excess d is investigated for a 50m long core section and the near-surface snow. High-pass filtered profiles are positively correlated, whereas the correlation between low-pass filtered profiles is negative. A post-depositional effect due to diffusion processes can be seen in a sub-annually resolved profile from snow-pit samples. Changes in the seasonality of the evolution of the snow cover and the consequences for stable-isotope content are demonstrated with data from ice core B31.

Winner-Take-All Contention of Innovation under Globalization: A Simulation Analysis and East Asia's Empirics

This paper sets out to examine how innovation enhances export competitiveness: The proposition that export volume becomes enhanced as more productivity-enhancing innovation is captured by the exporting economy is the focus of this study. From a Schumpeterian perspective, innovation can be characterized by continuous creation and subsequent diffusion of newer technologies on the basis of the exporters' existing capital stock. Then we highlight the theoretical possibility that concentration of innovative activities in a small group of "winner" economies would lead to larger shares of "winner" economies' exports of innovation-active commodities than those commodities for which technology involved is already mature. The world's export data corroborates this theoretical prediction overall, and a focus upon East Asia has revealed the region's increasing resort to technology-intensive commodity sectors, which has presumably been enabled through attracting technology-bearing inward foreign direct investment. Considering the overall gains from innovation, acceleration of full "cycle" of innovation and imitation might be a desirable option.

Has Low Productivity Constrained Competitiveness of African Firms? : Comparison of the Firm Performances with Asian Firms

It has been argued that poor productive performance is one of critical sources of stagnation of the African manufacturing sector, but firm-level empirical supports are limited. Using the inter-regional firm data of the garment industry, technical efficiency and its contribution to competitiveness measured as unit costs were compared between Kenyan and Bangladeshi firms. Our estimates indicated that there is no significant gap in the average technical efficiency of the two industries despite conservative estimation, although unit costs greatly differ between the two industries. Higher unit cost in Kenyan firms mainly stems from high labour cost, while impact of inefficiency is quite small. Productivity accounts little for the stagnation of garment industry in several African countries.

Value Chain Dynamics and Growth of Local Firms:The Case of Motorcycle Industry in Vietnam

Vietnam���s burgeoning market for motorcycles has attracted global industry eaders,players from developing countries, and local firms. This has led to a dynamic evolution of value chains. This paper presents an explanation of the varieties of the growth patterns xperienced by the local suppliers, focusing on the roles of customer and local supplier strategies. Case studies showed that while the role of customers may be important, strategies of suppliers to improve the ompetitive edge in the production of otorcycle components and to diversify into other products account for important ariations of growth trajectories among local suppliers. Findings presented in this paper suggest the need to direct more attention to strategy that local firms use to boost their competitive edge in business.

Clothing Export from sub-Saharan Africa : Impact on Poverty and Potential for Growth

Increases in clothing exports after 2000 signaled the first incidence of large-scale manufacturing exports from sub-Saharan Africa. Using firm-level information, this paper explores the potential of clothing exports for poverty reduction and further growth as seen in other low income countries. It shows that the garment exporting industries in Kenya and Madagascar have contributed poverty reduction in the short term by providing mass employment for female and less educated workers with wages beyond the poverty line. However, the long-term impact is not certain. High production costs and limited development of local firms weaken potential for further growth in the competitive world market. Upgrading of the market and improvement of efficiency are required to remain competitive for African industries, and governmental support for local participation are needed to facilitate technology transfer.

Linked versus Non-linked Firms in Innovation: The Effects of Economies of Network in Agglomeration in East Asia

This paper proposes a new mechanism linking innovation and network in developing economies to detect explicit production and information linkages and investigates the testable implications of these linkages using survey data gathered from manufacturing firms in East Asia. We found that firms with more information linkages tend to innovate more, have a higher probability of introducing new goods, introducing new goods to new markets using new technologies, and finding new partners located in remote areas. We also found that firms that dispatched engineers to customers achieved more innovations than firms that did not. These findings support the hypothesis that production linkages and face���to���face communication encourage product and process innovation.

Technology Choice in the IT Industry and Changes of the Trade Structure

In the IT industry, there has been a remarkable increase in the demand for system LSI. A system LSI must be produced, tailor-designed for each electrical appliance. It is said that this production method has made the IC cycle ambiguous in recent years. It can be sought that the choice of whether the economy pursues a development path centering on technology which is tradable or technology which is embodied in labor, depends on the historical background. The relationship between these two types of technologies is changing rapidly every one or two years. In this background, the analysis is focused on the new trend of technology. In the section 2, the newest trend of technology in the field of system LSI is explained. Then, which kind of technology will be developed and how it will have an affect in the near future, is considered.

FDI and Export Participation of Local Firms in Africa: The Case of the Kenyan Garment Industry

FDI in the garment sector has been the single case of large-scale manufacturing investment in African low-income countries since the 1990s. While FDI has triggered the development of local industries in many developing countries, it has not yet been realized in Africa. This paper describes the spillover process in the Kenyan garment industry and investigates the background of local firms' behavior through firm interviews and simulation of expected profits in export market. It shows that credit constraint, rather than absorptive capacity, is a primary source of inactive participation in export opportunity. Only firms which afford additional production facilities without sacrificing stable domestic supply may be motivated to start exporting. However, in comparison with successful Asian exporters, those firms were not as motivated as Asian firms due to the large gap in expected profits.

Innovation networks in China, Japan, and Korea : evidence from Japanese patent data

The growing importance of innovation in economic growth has encouraged the development of innovation capabilities in East Asia, within which China, Japan, and Korea are most important in terms of technological capabilities. Using Japanese patent data, we examine how knowledge networks have developed among these countries. We find that Japan's technological specialization saw little change, but those of Korea and China changed rapidly since 1970s. By the year 2009, technology specialization has become similar across three countries in the sense that the common field of prominent technology is "electronic circuits and communication technologies". Patent citations suggest that technology flows were largest in the electronic technology, pointing to the deepening of innovation networks in these countries.

The rise and fall in the price of food, fuel and manufactured goods : interdependency between prices and technology determining comparative advantages and development paths

Green innovation, which enables us to extract energy from food crops, caused a food shortage in 2008. Countries suffering severe damage started to reconsider their agricultural policy with the aim of becoming more autonomous. The food price hike of the time looks like a reversal of the celebrated Singer-Prebisch thesis proposed in the 1950s. This paper examines the consequences of this trend on the comparative advantages and development strategies of developing countries. For that purpose, first, trends and short-run fluctuations in the prices of fuel and bio-energy crops are investigated. It is shown that the price series of fuels and the crops are synchronized only after the fuel extracting technology came into effect. Second, the reversal of the Singer-Prebisch thesis is underpinned by the generic form of an endogenous growth model developed by Rebelo (1991). It is shown that as an economy grows, appreciation of the non-reproducible, such as mineral resources and raw labor, over the reproducible, such as capital goods, is the norm rather than an anomaly. Third, the consequences of the food price hike and underlying capital accumulation on the development strategies of labor-abundant and low-income countries are explored. It is concluded that the impact of the food price hikes on the alteration of a development strategy is only incremental, without reinforcement from raw-labor-saving innovation. A case study of inventions by JUKI Corporation, a world-leader in the sewing machine market exemplifies the fact that, of all the major inventions the company have made, raw-labor-saving inventions have not dominated, although JUKI's machines are sold to one of the most raw-labor-intensive industries.

Innovation networks in China, Japan, and Korea : further evidence from U.S. patent data

The growing importance of innovation in economic growth has encouraged the development of innovation capabilities in East Asia, within which China, Japan, and Korea are most important in terms of technological capabilities. Using U.S. patent data, we examine how knowledge networks have developed among these countries. We find that Japan's technological specialization saw gradual changes, but those of Korea and China changed rapidly since 1970s. By the year 2009, technology specialization has become similar across three countries in the sense that the common fields of prominent technology are electronics and semiconductors. Patent citations suggest that technology flows were largest in the electronics technology, pointing to the deepening of innovation networks in these countries. Together with our prior work, the Japanese and U.S. data produce similar conclusions about innovation networks.