<p>People live and work in local markets spatially distinct from one another, yet space is absent from most economic models of the national labor market. Workers choose the markets in which they will participate, but there are costs to mobility. Furthermore, cities are heterogeneous in a number of dimensions, including their local labor market productivity, their housing supply, and their offering of amenities.</p><p>I examine the impact of these spatial considerations on the dynamics of local labor markets and the national market to which they aggregate. First I study the patterns of location choice through a gravity model of migration applied to rich panel data from the U.S. I find that location choices respond to temporal shocks to the labor market, but only after controlling for local heterogeneity. Next, with this result as motivation, I turn to development of a dynamic spatial equilibrium of the national labor market. I make a technical contribution to work in dynamic equilibrium modeling by empirically implementing an island economy model of worker mobility. I quantify the importance of worker mobility costs versus local housing prices for explaining spatial variation in the unemployment rate. I find that the link between the local housing market and the local labor market is important for explaining the spatial dispersion in unemployment, but mobility costs are not. Finally, I further exploit the dynamic equilibrium framework to examine the effect of local housing policy on labor market growth. I find that housing supply regulation is a constraint to growth, but is only binding on cities that are particularly desirable because of their labor market opportunities or amenities. I find that some lightly regulated markets have a contingent of population that has been pushed out of more regulated markets by high housing prices.</p> / Dissertation

Nas últimas décadas, o domínio tecnológico tem sido enfatizado como elemento de progresso tanto no âmbito das empresas como no dos países. A tecnologia está presente na infra-estrutura das atividades econômicas e de toda a sociedade. Dessa forma, a tecnologia da informação é cada vez mais importante para o desenvolvimento tecnológico, mesmo em áreas não diretamente ligadas a ela. O setor de semicondutores, que em conjunto com os setores de computação e de software forma a indústria de microeletrônica, tem tido especial destaque na evolução da economia mundial. No Brasil, entretanto, o setor de semicondutores permanece restrito a um pequeno grupo de empresas. Neste contexto, com o propósito de desenvolver o setor de microeletrônica no Brasil, o governo federal, por meio do Ministério da Ciência, Tecnologia e Inovação, investiu na criação de uma empresa de semicondutores, no estado do Rio Grande do Sul. A empresa criada constitui o objeto de pesquisa deste estudo de caso, desenvolvido ao longo de 2011, com foco em seu desenho organizacional. Os objetivos alcançados com o presente trabalho foram os seguintes: levantamento dos modelos de desenho organizacional na literatura, tanto do setor privado como do setor público; estudo das características administrativas de instituições públicas brasileiras, sua forma de operar e seu desenho organizacional, considerando suas várias dimensões; levantamento das características do setor de semicondutores, com foco no surgimento de empresas deste setor em países em desenvolvimento; avaliação das diferentes dimensões do desenho organizacional, suas interdependências e equilíbrios dinâmicos, por meio de um estudo de caso, considerando a realidade de empresa pública brasileira. A metodologia utilizada foi o estudo de caso, com abordagem qualitativa. A coleta de dados foi realizada por meio de observação direta, análise documental e entrevistas semiestruturadas. A principal contribuição deste trabalho consiste na análise do desenho organizacional adotado pela empresa em estudo, considerando a organização de uma maneira integrada e sistêmica, incluindo todas as cinco dimensões do desenho organizacional Estratégia, Pessoas, Sistemas de Recompensa, Processos e Estrutura, além de identificar as interações entre as diversas dimensões e entre estas e o ambiente de atuação da empresa. Outra contribuição do presente trabalho está relacionada à análise da evolução dos subsistemas produtivos na organização ao longo do tempo, assim como a evolução dos objetivos de desempenho a serem buscados pela empresa. Considerando que os estudos acadêmicos sobre desenho organizacional no setor público brasileiro são relativamente escassos, os resultados obtidos neste trabalho consistem em contribuição para a teoria, uma vez que abrangem fatores específicos do setor público e sua influência sobre programas de reestruturação e mudança. Além disso, diante da grande necessidade de melhoria do setor, a descrição do caso e a análise dos resultados apresentam evidente aplicação prática, uma vez que proporcionam uma base para trabalhos futuros. / In the last decades, technological dominium has been emphasized as a progress element even in the ambit of firms as of countries. Technology is present in the infrastructure of economic activities as in the whole society. In this way, information technology is being each time more important to technological development, even in areas not directly linked to it. The semiconductor sector, which forms the microelectronic industry together with computer and software sectors, has received special highlight in the evolution of the world economy. In Brazil, however, the semiconductor sector remains restricted to a small group of firms. In this context, with the propose of developing the microelectronic sector in Brazil, the federal government, through the Science, Technology and Innovation Ministry, invested in the creation of a semiconductor firm, in Rio Grande do Sul state. The created firm consists in the research object of this study case, developed along 2011, with focus on its organizational design. The objectives reached with the present work were: identification of organizational design models in the literature, both of the private and the public sectors; study of administrative characteristics of Brazilian public institutions, their modus operandi and organizational design, considering its various dimensions; identification of semiconductors characteristics, with focus on the emerging of firms in this sector in developing countries; evaluation of different dimensions of organizational design, its interdependencies and dynamic equilibrium, through a study case, considering the reality of a Brazilian public firm. The methodology used was case study, with qualitative approach. Data were collected through direct observation, documental analysis and semi-structured interviews. The main contribution of this work is the analysis of the organizational design adopted by the studied firm, considering the organization in an integrated and systemic manner, including all the five dimensions of its organizational design Strategy, People, Reward Systems, Process and Structure, besides identifying the interactions between these dimension and between each dimensions and the organizations environment. Another contribution of this work is related to the analysis of the evolution of the productive subsystems in the organization along the time, so as the evolution of the performance objectives to be reached by the firm. Considering that academic studies about organizational design in the Brazilian public sector are relatively scarce, the results obtained in this work consist of contribution to theory, since they enclose specific aspects of the public sector and their influence in restructuring and change programs. Moreover, given the major need for improvement of the sector, the case description and the analysis of the results present evident practical application, because they provide a base for future work.

<p>This dissertation investigates the non-market value of environmental quality in several contexts with attention paid to equilibrium effects. Chapter One contributes to the ongoing debate concerning the effect of various actions taken by the U.S. Environmental Protection Agency under CERCLA, commonly known as the Superfund Program, on housing prices. The study differs from national sample analyses and site-specific analyses by providing policy-relevant estimates of the hedonic price function in a particular region for the average site. Further, an estimate of the effect on housing prices is given for each of the major events that occur under a typical Superfund remediation. Using house and time-varying census tract fixed effects, I find a 7.3% increase in sales price for houses within 3 km of a site that moves through the complete Superfund program. The analysis gives evidence of positive price appreciation for housing markets and serves as a lower bound for measuring remediation benefits. Chapter Two proposes a new dynamic general equilibrium model of residential location choice with social spillovers and uses it to evaluate the equilibrium consequences of changes in pollution exposure. In particular, I investigate the hypothesis of ``minority move-in,'' which postulates that disproportionate exposure to pollution results from minorities and low-income households trading off such exposure for lower housing costs. Second, I address the question of whether economic incentives caused by differences in willingness to pay across socioeconomic status can explain why polluters disproportionately locate near disadvantaged populations in order to minimize expenses from collective action bargaining over the negative externality. Simulations indicate ``minority move-in'' likely does account for some of the imbalance in exposure to pollution across socioeconomic status. Further, general equilibrium estimates reveal that equilibrium sorting behavior widens the gap in willingness to pay for environmental quality between minority and white households, and between high and low-income households. The disparity in general equilibrium willingness to pay to avoid toxic emissions provides economic incentives for polluters to target disadvantaged populations. Chapter Three investigates how information contained in the U.S. Environmental Protection Agency's Toxic Release Inventory program affects prices in the housing market. First, I use a reduction in the reporting requirement threshold in 2001 as a quasi-experiment to determine whether prices change for existing firms who, as a result of the change, must report. Second, the existence of a reporting threshold creates a discontinuity in treatment than can be exploited. I estimate a regression discontinuity model that assumes that site unobservables are balanced in a neighborhood of the discontinuity. Using a difference-in-differences estimator for the first specification, I find that listing a site in the Toxic Release Inventory lowers prices by 3.1% within a three kilometer radius of the site, and that the effect is stronger at shorter distances. The regression discontinuity model produces qualitatively similar results that are smaller in magnitude but still significant. The results suggest that households to capitalize the information contained in the Toxic Release Inventory. However, since the treatment sites under consideration have virtually no emissions, these results do not contradict previous findings in the literature that toxic air emissions are unrelated to prices. Rather, they suggest that households might be concerned about the dangers of toxic chemicals that might result from an emergency or catastrophic accident.</p> / Dissertation

Nas últimas décadas, o domínio tecnológico tem sido enfatizado como elemento de progresso tanto no âmbito das empresas como no dos países. A tecnologia está presente na infra-estrutura das atividades econômicas e de toda a sociedade. Dessa forma, a tecnologia da informação é cada vez mais importante para o desenvolvimento tecnológico, mesmo em áreas não diretamente ligadas a ela. O setor de semicondutores, que em conjunto com os setores de computação e de software forma a indústria de microeletrônica, tem tido especial destaque na evolução da economia mundial. No Brasil, entretanto, o setor de semicondutores permanece restrito a um pequeno grupo de empresas. Neste contexto, com o propósito de desenvolver o setor de microeletrônica no Brasil, o governo federal, por meio do Ministério da Ciência, Tecnologia e Inovação, investiu na criação de uma empresa de semicondutores, no estado do Rio Grande do Sul. A empresa criada constitui o objeto de pesquisa deste estudo de caso, desenvolvido ao longo de 2011, com foco em seu desenho organizacional. Os objetivos alcançados com o presente trabalho foram os seguintes: levantamento dos modelos de desenho organizacional na literatura, tanto do setor privado como do setor público; estudo das características administrativas de instituições públicas brasileiras, sua forma de operar e seu desenho organizacional, considerando suas várias dimensões; levantamento das características do setor de semicondutores, com foco no surgimento de empresas deste setor em países em desenvolvimento; avaliação das diferentes dimensões do desenho organizacional, suas interdependências e equilíbrios dinâmicos, por meio de um estudo de caso, considerando a realidade de empresa pública brasileira. A metodologia utilizada foi o estudo de caso, com abordagem qualitativa. A coleta de dados foi realizada por meio de observação direta, análise documental e entrevistas semiestruturadas. A principal contribuição deste trabalho consiste na análise do desenho organizacional adotado pela empresa em estudo, considerando a organização de uma maneira integrada e sistêmica, incluindo todas as cinco dimensões do desenho organizacional Estratégia, Pessoas, Sistemas de Recompensa, Processos e Estrutura, além de identificar as interações entre as diversas dimensões e entre estas e o ambiente de atuação da empresa. Outra contribuição do presente trabalho está relacionada à análise da evolução dos subsistemas produtivos na organização ao longo do tempo, assim como a evolução dos objetivos de desempenho a serem buscados pela empresa. Considerando que os estudos acadêmicos sobre desenho organizacional no setor público brasileiro são relativamente escassos, os resultados obtidos neste trabalho consistem em contribuição para a teoria, uma vez que abrangem fatores específicos do setor público e sua influência sobre programas de reestruturação e mudança. Além disso, diante da grande necessidade de melhoria do setor, a descrição do caso e a análise dos resultados apresentam evidente aplicação prática, uma vez que proporcionam uma base para trabalhos futuros. / In the last decades, technological dominium has been emphasized as a progress element even in the ambit of firms as of countries. Technology is present in the infrastructure of economic activities as in the whole society. In this way, information technology is being each time more important to technological development, even in areas not directly linked to it. The semiconductor sector, which forms the microelectronic industry together with computer and software sectors, has received special highlight in the evolution of the world economy. In Brazil, however, the semiconductor sector remains restricted to a small group of firms. In this context, with the propose of developing the microelectronic sector in Brazil, the federal government, through the Science, Technology and Innovation Ministry, invested in the creation of a semiconductor firm, in Rio Grande do Sul state. The created firm consists in the research object of this study case, developed along 2011, with focus on its organizational design. The objectives reached with the present work were: identification of organizational design models in the literature, both of the private and the public sectors; study of administrative characteristics of Brazilian public institutions, their modus operandi and organizational design, considering its various dimensions; identification of semiconductors characteristics, with focus on the emerging of firms in this sector in developing countries; evaluation of different dimensions of organizational design, its interdependencies and dynamic equilibrium, through a study case, considering the reality of a Brazilian public firm. The methodology used was case study, with qualitative approach. Data were collected through direct observation, documental analysis and semi-structured interviews. The main contribution of this work is the analysis of the organizational design adopted by the studied firm, considering the organization in an integrated and systemic manner, including all the five dimensions of its organizational design Strategy, People, Reward Systems, Process and Structure, besides identifying the interactions between these dimension and between each dimensions and the organizations environment. Another contribution of this work is related to the analysis of the evolution of the productive subsystems in the organization along the time, so as the evolution of the performance objectives to be reached by the firm. Considering that academic studies about organizational design in the Brazilian public sector are relatively scarce, the results obtained in this work consist of contribution to theory, since they enclose specific aspects of the public sector and their influence in restructuring and change programs. Moreover, given the major need for improvement of the sector, the case description and the analysis of the results present evident practical application, because they provide a base for future work.

Estruturas líquidas cristalinas estão presentes em materiais compostos por moléculas com anisotropia de forma e são caracterizadas por uma ordem orientacional de longo alcance. Na mesofase nemática as moléculas alongadas tendem a se alinhar paralelas entre si, a direção média de orientação define é caracterizada por um vetor unitário, chamado de diretor n. Os cristais líquidos liotrópicos são obtidos usualmente a partir da dispersão de moléculas anfílicas em água. Essas moléculas anfílicas, por terem uma parte polar e uma parte apolar, tendem a formar agregados anisotrópicos, com a parte polar da molécula na superfície. Esse tipo de estrutura esta presente em todos os seres vivos e o exemplo mais clássico é a membrana da célula. A existência de uma superfície de contorno ou uma fronteira modifica as propriedades de um material na vizinhança dessa fronteira. Isso é particularmente verdadeiro para os cristais líquidos, que são muitos sensíveis as condições de contorno, mesmos quando estas não são tão intensas. De fato essa propriedade e bastante útil para a fabricação de dispositivos eletro-ó pticos. Um dos efeitos de superfície mais evidente é a mudança no ordenamento das moléculas devido a quebra de simetria na superfície. Nas fases nemáticas esse efeito microscópico resulta na formação de uma camada superficial com uma ordem posicional que se estende ao longo de uma certa distância no volume. 0 outro efeito resulta da origem a mudanças significativas no estado orientacional das moléculas no volume devido a presença de forças superficiais. Esse efeito é conhecido como ancoramento. Na ausência de campos extemos ou condições de contorno qualquer orientação é igualmente provável. Neste trabalho serão apresentados os resultados de investigação das propriedades de cristais líquidos liotrópicos na interface com um substrata. Estudamos o comportamento dinâmico da camada superficial quando o campo magnético é aplicado e induz uma re­ orientação do diretor. Nesse estudo são utilizadas amostras de cristal líquidos liotrópicos. / Liquid crystalline structures are found in materials made from molecules which are anisotropic in shape; such material are characterized mainly by a long range orientational order. In the nematic phase, the rodlike molecules tend to align parallel to each other. The average orientation defines a unit vector, called director n. Lyotropic liquid crystals are usually obtained by the dispersion of amphiphilic molecules in water. Due the fact that these molecules present a polar head and a non-polar tail, they tend to form aggregates with the polar part at the aggregate surface. This type of struc­ ture is present in all living being; the most classical example is the cell membrane. The existence of a boundary surface affects the properties of a material close to this boundary. This particularly true for liquid crystals, which are very sensitive to boundary conditions, even when weak. Indeed, this property is quite useful in the fabrication of electro-optic devices. One of the most obvious surface effect is the change in the molecules organization due to a breaking of the symmetry at the boundary surface. In the nematic phases, this microscopic effect results in the formation of a surface la yer with a positional order that extends through the bulk up to a certain distance from the surface. The other effect of the surface results in a change in the orientational state of the molecules in the volume due to the sur face forces. This macroscopic effect is known as anchoring. In the absence of any external field or boundary conditions, all molecular orientation is equally probable. In this work, we will present some results of the investigation of the properties of lyotropic liquid crystals at the interface with a solid substrate. We have studied the dy­ namic of the surface layer when a applied magnetic field induces a reorientation of the nematic director. In this study different systems were used: lyotropic liquid crystals in the nematic phase, ferronematics (nematic phase doped with ferrofluid) and filled nematics (nematic phase doped with silica nano-spheres). By means of transmittance measurements.

Estruturas líquidas cristalinas estão presentes em materiais compostos por moléculas com anisotropia de forma e são caracterizadas por uma ordem orientacional de longo alcance. Na mesofase nemática as moléculas alongadas tendem a se alinhar paralelas entre si, a direção média de orientação define é caracterizada por um vetor unitário, chamado de diretor n. Os cristais líquidos liotrópicos são obtidos usualmente a partir da dispersão de moléculas anfílicas em água. Essas moléculas anfílicas, por terem uma parte polar e uma parte apolar, tendem a formar agregados anisotrópicos, com a parte polar da molécula na superfície. Esse tipo de estrutura esta presente em todos os seres vivos e o exemplo mais clássico é a membrana da célula. A existência de uma superfície de contorno ou uma fronteira modifica as propriedades de um material na vizinhança dessa fronteira. Isso é particularmente verdadeiro para os cristais líquidos, que são muitos sensíveis as condições de contorno, mesmos quando estas não são tão intensas. De fato essa propriedade e bastante útil para a fabricação de dispositivos eletro-ó pticos. Um dos efeitos de superfície mais evidente é a mudança no ordenamento das moléculas devido a quebra de simetria na superfície. Nas fases nemáticas esse efeito microscópico resulta na formação de uma camada superficial com uma ordem posicional que se estende ao longo de uma certa distância no volume. 0 outro efeito resulta da origem a mudanças significativas no estado orientacional das moléculas no volume devido a presença de forças superficiais. Esse efeito é conhecido como ancoramento. Na ausência de campos extemos ou condições de contorno qualquer orientação é igualmente provável. Neste trabalho serão apresentados os resultados de investigação das propriedades de cristais líquidos liotrópicos na interface com um substrata. Estudamos o comportamento dinâmico da camada superficial quando o campo magnético é aplicado e induz uma re­ orientação do diretor. Nesse estudo são utilizadas amostras de cristal líquidos liotrópicos. / Liquid crystalline structures are found in materials made from molecules which are anisotropic in shape; such material are characterized mainly by a long range orientational order. In the nematic phase, the rodlike molecules tend to align parallel to each other. The average orientation defines a unit vector, called director n. Lyotropic liquid crystals are usually obtained by the dispersion of amphiphilic molecules in water. Due the fact that these molecules present a polar head and a non-polar tail, they tend to form aggregates with the polar part at the aggregate surface. This type of struc­ ture is present in all living being; the most classical example is the cell membrane. The existence of a boundary surface affects the properties of a material close to this boundary. This particularly true for liquid crystals, which are very sensitive to boundary conditions, even when weak. Indeed, this property is quite useful in the fabrication of electro-optic devices. One of the most obvious surface effect is the change in the molecules organization due to a breaking of the symmetry at the boundary surface. In the nematic phases, this microscopic effect results in the formation of a surface la yer with a positional order that extends through the bulk up to a certain distance from the surface. The other effect of the surface results in a change in the orientational state of the molecules in the volume due to the sur face forces. This macroscopic effect is known as anchoring. In the absence of any external field or boundary conditions, all molecular orientation is equally probable. In this work, we will present some results of the investigation of the properties of lyotropic liquid crystals at the interface with a solid substrate. We have studied the dy­ namic of the surface layer when a applied magnetic field induces a reorientation of the nematic director. In this study different systems were used: lyotropic liquid crystals in the nematic phase, ferronematics (nematic phase doped with ferrofluid) and filled nematics (nematic phase doped with silica nano-spheres). By means of transmittance measurements.

Inwardly rectifying potassium (Kir) channels are essential for controlling the excitability of eukaryotic cells, forming a key part of the inter-cellular signalling system in multi-cellular organisms. However, as prokaryotic (KirBac) channels are less technically challenging to study in vitro and have been shown to be directly homologous to eukaryotic channels, they are often studied in lieu of their mammalian counterparts. A vital feature of Kir and KirBac channels is their mechanism for opening and closing, or their gating: this study predominantly features observations of open and/or closed channel populations. A well-characterised member of the KirBac family, KirBac1.1, has been successfully expressed, purified into detergent micelles, and doubly labelled with fluorescent maleimide dyes in order to enable observation of confocal-in-solution Förster Resonance Energy Transfer (FRET) at the single molecule level. Results demonstrate single-molecule FRET signals from KirBac1.1 and therefore represent the first single-molecule FRET observations from a KirBac channel. Perturbation of the open-closed dynamic equilibrium was performed via activatory point mutations, changes in pH, and ligand binding. A protocol for reconstitution into nanodiscs was optimised in order to more closely approximate native conditions, and the single-molecule FRET observations repeated. This thesis presents a comparison between measurements made using the detergent solubilisation system and those made using nanodiscs.

From the Proceedings of the 1975 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 11-12, 1975, Tempe, Arizona / Traditionally, watershed management is concerned with water and sediment yield, vegetation, soils, and meteorology, but not with geomorphology. Often it is in this field that the explanation can be found for the formation and present condition of a watershed and its future development. Examples are presented to demonstrate that factors in the hydraulic geometry of streams indicate whether a watershed is in an active stage of landform development, or is in dynamic equilibrium. Some general guides for the practitioner are provided. Watershed management research cannot afford to ignore the basic geomorphic setting of watersheds. If geomorphology is not considered, the researcher's results could be misinterpreted.

Several misconceptions show up when learners answer questions on Chemical Equilibrium during examinations. Literature from other researchers shows similar trend of misconceptions (Johnstone, 2000; Morais, Paiva and Barros, 2007; Adesoji and Babatunde, 2008) for example, ‘apply pressure to the reactants’ (Johnstone, 2000). This shows that Chemistry has no meaning to these learners and they end up with misconceptions as they try to memorise facts in order to pass examinations. Learners are taught before writing these examinations, but how are they taught the concepts of Chemical Equilibrium? A descriptive approach was used on an exploratory survey conducted in Thohoyandou Cluster among Physical Science (Chemistry) FET band Educators. Cluster sampling of 40 educators from 18 randomly sampled schools responded to questionnaires. Five ‘well experienced’ educators who have been producing ‘good’ results at Grade 12 NSC examinations and two Physical Sciences subject advisors were interviewed. Using Spearman Brown Split-Half statistical method a 0,891 reliability coefficient was obtained. Research results show lack or under utilisation of laboratory equipment, teaching strategies which promote rote learning. Lack of confidence of educators due to deficiency in topic content knowledge and pedagogical skills which promote conceptual understanding were identified. Problem of English language leading to communication breakdown between educator-learners and between learner-subject leading to emergency of knowledge gaps in learners. Educators consider professional development through re-training and workshops on subject content matter and teaching strategies as the way forward to improve the quality of teaching. Topic specific PCK focusing on problem-solving strategy was recommended as a means to increasing educators’ efficiency in teaching and enhance learners’ comprehension and achievement in Physical Science. / Science and Technology Education / M. Sc. (Mathematics, Science and Technology Education (Chemistry Education))

An den Handelsbörsen der Welt, hat der Anteil unsichtbarer Luidität in den letzten Jahren dramatisch zugenommen. Obwohl dieser Trend zunehmend in den Fokus regulatorischer Debatten und akademischer Dikussionen rückt, sind sich Forscher und die Aufsichtsbehörden über die Implikationen und entsprechende regulatorische Maßnahmen uneins. In der vorliegenden Arbeit, werden die damit verbundenen Fragestellungen in drei separaten Kapiteln theoretisch und empirisch untersucht. Mit Hilfe eines speziellen NASDAQ Datensatzes, werden in Kapitel 1 die Marktfaktoren, die unsichtbaren Liquidität begünstigen sowie den Einfluß, den unsichtbare Liquidät auf Märkte ausübt, empirisch ausgewertet. Wir zeigen, daß die Querschnittsvariation unsichtbarer Liquidität entlang des Aktienuniversums in einem hohen Maße durch sichtbare Markteigenschaften erklärt wird. Wir zeigen, daß unsichtbare Order gegenüber sichtbaren Ordern signifikant stärkere Preisfluktuationen hervorrufen. Unsere Resultate geben Grund zu der Annahme, daß Märkte mit hoher unsichtbarer Liquidät volatiler sind und höheren Marktreibungen ausgesetzt sind. In Kapitel 2 entwickeln wir ein strukturelles Handelsmodell und untersuchen die optimale Handelsstrategie mit unsichtbaren Ordern. In diesem Rahmen leiten wir für verschiedene Marktspezifikationen explizite Charakterisierungen der sogenannten optimalen Exposure-Größe her. Unter anderem zeigen wir, daß der Einsatz unsichtbarer Order Transaktionskosten signifikant reduzieren kann. In Kapitel 3 entwickeln wir ein dynamisches, Gleichgewichtsmodell in einem Limitorderbuchmarkt. Innerhalb dieses theoretischen Rahmens können die empirischen Beobachtungen des ersten un zweiten Kapitels rationalisiert werden. Insbesondere zeigen wir daß große versteckte Order Marktineffizienzen hervorrufen und Preisfluktuationen verstärken, indem sie die Koordination zwischen Angebots- und Nachfrageseite schwächen können. / In recent years, the proliferation of hidden liquidity in financial markets has increased dramatically and shifted to the center regulatory debates and market micro-structure panels. Yet investors, scientists and policy makers are at odds about its implications and the adequate regulatory responses. This thesis addresses these issues in three separate chapters on both empirical and theoretical grounds. Chapter 1 provides an empirical investigation of the determinants and impact of hidden order submissions. We report that the cross-sectional variation of hidden liquidity is well explained by observable market characteristics. Second, our results suggest that the hidden orders generate substantial price reactions. Our results suggests that hidden liquidity increases market volatility and trading frictions. Chapter 2 proposes a structural trading model. We investigate trader’s optimal trading strategies with respect to order-exposure in limit order book markets. The optimal exposure size marks a trade-off between costs and benefits of exposure. Our model provides explicit characterizations of the optimal exposure size for various market specifications. Model parameters and exposure strategies are estimated through high-frequency order book data. Our results suggest that hidden orders can substantially enhance trade performance. Chapter 3 develops a dynamic equilibrium model with a public primary market and an off-exchange trading mechanism. Our theory correctly predicts the key findings of chapter one and two. For instance, we show that large hidden orders cause excess returns and increase market volatility and correctly predict the role of the observable market characteristics in the origination of hidden liquidity.