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The first essay of this dissertation focuses on studying the relationship between private politics and corporate environmentalism. This work analyzes the determinants and effects of two private political actions, boycotts and proxy contests. The analysis shows that: (i) the size of a firm is an important predictor of whether a firm will be chosen as a target of an activist campaign; (ii) firms headquartered in states with larger environmental constituencies are more likely to be targeted by activist campaigns; (iii) "dirty firms" (with larger relative or absolute emissions and/or high level of regulatory scrutiny) are more likely to become targets of an activist campaign; and (iv) private political campaigns are effective in improving the environmental performance of their targets. The second essay examines the trends in Total Factor Productivity (TFP) and investigates the effects of major changes in the economy on measures of TFP in eight industries during the Interwar period from 1919 through 1939. TFP estimates show that each industry followed a different path of TFP change. There is no consistent evidence on large TFP decline during the years 1929-33 in the industries studied, as proposed in the literature. TFP measures also do not support the hypothesis that the 1930s were a period of interrupted TFP growth but there is evidence that five industries out of eight had higher productivity in the 1930s than in the 1920s. Regression analysis of major determinants of the TFP change for the motor vehicles and the cotton goods industry shows that TFP fell with increases in employment and strike activity. The NRA code might have also contributed to a decline in TFP.

In large-scale distributed systems, where adversarial attacks can have widespread impact, authentication provides protection from threats involving impersonation of entities and tampering of data. Practical solutions to authentication problems in distributed systems must meet specific constraints of the target system, and provide a reasonable balance between security and cost. The goal of this dissertation is to address the problem of building practical and efficient authentication mechanisms to secure distributed applications. This dissertation presents techniques to construct efficient digital signature schemes using trapdoor hash functions for various distributed applications. Trapdoor hash functions are collision-resistant hash functions associated with a secret trapdoor key that allows the key-holder to find collisions between hashes of different messages. The main contributions of this dissertation are as follows: 1. A common problem with conventional trapdoor hash functions is that revealing a collision producing message pair allows an entity to compute additional collisions without knowledge of the trapdoor key. To overcome this problem, we design an efficient trapdoor hash function that prevents all entities except the trapdoor key-holder from computing collisions regardless of whether collision producing message pairs are revealed by the key-holder. 2. We design a technique to construct efficient proxy signatures using trapdoor hash functions to authenticate and authorize agents acting on behalf of users in agent-based computing systems. Our technique provides agent authentication, assurance of agreement between delegator and agent, security without relying on secure communication channels and control over an agent’s capabilities. 3. We develop a trapdoor hash-based signature amortization technique for authenticating real-time, delay-sensitive streams. Our technique provides independent verifiability of blocks comprising a stream, minimizes sender-side and receiver-side delays, minimizes communication overhead, and avoids transmission of redundant information. 4. We demonstrate the practical efficacy of our trapdoor hash-based techniques for signature amortization and proxy signature construction by presenting discrete log-based instantiations of the generic techniques that are efficient to compute, and produce short signatures. Our detailed performance analyses demonstrate that the proposed schemes outperform existing schemes in computation cost and signature size. We also present proofs for security of the proposed discrete-log based instantiations against forgery attacks under the discrete-log assumption.

This paper looks at whether firms’ credit ratings are negatively affected by litigation risk after controlling for known factors that affect credit ratings. The conventional wisdom is that litigation risk and credit ratings have an inverse relationship. However, my hypothesis is that the inverse relationship will not be stable if the model of credit ratings has taken other factors into account. The methodology first constructs a model of litigation risk, and then regress the credit ratings on the measurement of litigation risk. Previous empirical research on litigation risk measurement uses industry proxies as indicators for litigation risk. In this paper, I include firm characteristics and the Beneish M-score (a determinant for earnings manipulation) in addition to the industry proxy to construct an alternative model measuring litigation risk. I find that supplementing the Francis, Philbrick and Schipper (1994a, b; hereafter FPS) industry proxy with measures of firm characteristics improves predictive ability. In the model of credit ratings, I find that the change of litigation risk has a negative correlation with the credit ratings. However, the negative coefficient on the change of litigation risk changes to a positive one after controlling for other variables such as firm size, return on asset, and interest coverage ratio. This finding provides support for the hypothesis that the negative correlation between the credit ratings and litigation risk is not stable. This suggests that credit ratings may not incorporate litigation risk specifically although litigation can lead to firms’ financial damage and reputation crisis. However, the negative coefficient on the change of litigation risk remains unchanged when I control for the year fixed effects. I also find a negative correlation between the year 2007 and credit ratings due to financial crisis. The results are not conclusive given the likely simultaneous determination of litigation risk and credit ratings.

Made available in DSpace on 2013-08-07T18:42:30Z (GMT). No. of bitstreams: 1 000424471-Texto+Completo-0.pdf: 3818721 bytes, checksum: d6fbd6820f37d0e5f23b429ebe486f73 (MD5) Previous issue date: 2010 / Currently, many different services are available through the Internet and there is a growing demand for these applications. Considering that the Internet is not secure, the confidentiality of such information is a factor of increasing importance. To overcome this problem, many security techniques have emerged and each company has adopted the policies in a different way, but with a tendency to adopt the model of Service-Oriented Architectures. Sometimes different services with different security policies need to be grouped to work together, which makes it difficult to create an application that follows this pattern. A new approach is needed to facilitate the coexistence of these techniques in a productive manner. Based on these requirements, this paper presents a model aimed at the automatic processing of security features to services ordered in Service Oriented Architectures, this model serves as an intermediate system able to “translate” the safety techniques for a particular format. Based on this model, it is presented a prototype able to automatically handle different asymmetric encryption algorithms, including RSA, DSA and ECDSA. This study is to demonstrate the effectiveness of the model through a case study, presenting a situation that can be adopted by real applications. / Atualmente, diversos serviços são disponibilizados pela Internet e há uma crescente demanda por estas aplicações. Considerando que a Internet não é uma rede segura, a confidencialidade de informações que circulam na rede é um fator de importância cada vez maior. Visando solucionar este problema, várias técnicas de segurança surgiram e cada empresa as adotou em suas políticas de uma forma diferente. Porém com a tendência de adoção do modelo de Arquiteturas Orientadas a Serviços, diferentes serviços com diferentes políticas de segurança necessitaram ser agrupados para que pudessem trabalhar em conjunto, o que acabou dificultando a criação de uma aplicação que segue um determinado padrão. Uma nova abordagem se faz necessária para facilitar a coexistência destas técnicas de segurança de uma forma produtiva. Assim, este trabalho apresenta um modelo voltado ao tratamento automático de características de segurança para serviços ordenados em Arquiteturas Orientadas a Serviço. Este modelo atua como um sistema intermediário capaz de “traduzir” as técnicas de segurança para um formato determinado. Com base neste modelo é apresentado um protótipo capaz de tratar automaticamente diferentes algoritmos de criptografia assimétrica, entre eles RSA, DSA e ECDSA. O objetivo do trabalho é testar a efetividade do modelo por meio de um estudo de caso, apresentando uma situação que este pode ser adotado por aplicações reais.

O presente trabalho tem por objetivo analisar o papel do estreito de Ormuz nas dinâmicas de competição no Golfo Pérsico. Ormuz é um estreito geograficamente estratégico, uma vez que é a única via marítima entre o Golfo Pérsico, o Golfo de Omã e o Oceano Índico e encontra-se em uma área rica em hidrocarbonetos. Em vista disso, o primeiro capítulo busca analisar o conceito e as características que qualificam a relevância que alguns estreitos possuem para o Sistema Internacional, caracterizando-os como Pontos de Estrangulamento e, nesse sentido, averiguar as razões que definem o estreito de Ormuz como o principal ponto de estrangulamento marítimo no mundo. Já o segundo capítulo tem como foco o estudo da Competição Estratégica, estabelecida entre Estados Unidos e Irã (2003-2013), que somente tornou-se possível graças às características de Ormuz (e, à assimetria de capacidades). Por fim, o terceiro capítulo procura averiguar o papel do estreito na escalada das rivalidades entre Arábia Saudita e Irã que deflagram a Guerra Proxy, e o seu transbordamento para outros pontos de estrangulamento do Oriente Médio. Espera-se como resultado oferecer uma melhor contextualização e compreensão sobre o tema de Ormuz em particular, bem como dos pontos de estrangulamento, contribuindo dessa forma para a instrumentalização dessas categorias no estudo das Relações Internacionais contemporâneas. / This study aims to analyze the Strait of Hormuz role in the competition dynamics in the Persian Gulf. Hormuz is a strait geographically strategic, since it is the only maritime way between the Persian Gulf, the Gulf of Oman and the Indian Ocean and is located in an area rich in hydrocarbons. In view of this, the first chapter analyzes the concept and characteristics that qualify the relevance of some straits to the International System, characterizing them as Choke points and, accordingly, find out the reasons that define the Strait of Hormuz as the main maritime choke point in the world. The second chapter focuses on the study of the Strategic Competition, established between the United States and Iran (2003-2013), which only became possible because of the characteristics of Hormuz (and because of capacity asymmetry). Finally, the third chapter seeks to ascertain the strait role in escalating rivalries between Saudi Arabia and Iran that trigger the Proxy War and its spillover to other bottlenecks in the Middle East. It is expected as a result provide better context and understanding of Hormuz particular theme and bottlenecks, thus contributing to the exploitation of these categories in the study of contemporary international relations.

OBJECTIVE: The vast majority of physicians frequently faces ethical dilemmas and feels overwhelmed as a result. Those at Boston Medical Center are no exception. Various studies show more adept handling of ethical issues can improve the quality of care and patient safety by reducing moral distress of physicians and fostering better patient-physician relationship. The method of Preventive Ethics, which actively identifies recurrent themes and underlying systematic issues among ethics consultations, is more effective than the traditional, case-by-case approach in reducing the number of ethical conflicts. The purpose of this study is to identify common themes prompting ethics consultations and any hotspots among recurrent ethical dilemmas at Boston Medical Center by using the Armstrong Clinical Ethics Coding System. METHODS: A total of 32 ethics consultations handled by the BMC Ethics Committee between October 2010 and April 2013 were reviewed. Each consultation was coded using the Armstrong Clinical Ethics Coding System. The data was analyzed to identify the types of ethical dilemma that are most prevalent at BMC. The consultations involving the most frequently occurring issues were evaluated further to expose common themes among these cases and potential underlying systematic failures. RESULT: "Clinical Candidacy or Risk / Benefit Analysis" (6.25%), "Concern About Decision Maker Choices" (14.6%) and "Futility / Inappropriate or Nonbeneficial Treatment" (13.5%) were the most prevalent types of ethical issues at BMC. Not only are these three frequently occurring, they also have a very high tendency to occur simultaneously. Further analysis of consultations involving these three issues revealed that at BMC, there are frequent instances of conflict, in which family members serving as healthcare proxies disagreed with physicians in deciding the best interest of patients with severe ailments, ultimately precipitating ethics consultations. DISCUSSION: Comparison with similar retrospective studies previously carried out at other institutions suggests that consultation involving the issue of futility may be more frequently occurring at BMC, which might be coming from unique systematic problems. Several interventions such as improved policies or educational training in physician-family communication should be considered. CONCLUSION: According to the principles of Preventive Ethics, the issue of physician-healthcare proxy conflict regarding patient futility should be issue to be addressed at BMC. The Armstrong Clinical Ethics Coding System can serve as a much needed standard documentation format for ethics consultations, which would open up the possibility of more detailed future studies

The environment of deposition of the Ohio Shale of the Appalachian Basin has been studied extensively using various geochemical proxies for each of its members. The accumulation of organic matter (OM) and its preservation in the Late Devonian-Early Mississippian black shales of central Kentucky have been studied extensively, especially the possible correlations between trace metal contents and water-column oxygenation. Previous work has centered on geochemical, petrographic, and isotopic analysis of samples collected throughout the central Appalachian Basin. Mechanisms for OM preservation include high productivity, enhanced preservation due to dysoxic or anoxic bottom waters, and a feedback loop due to high productivity that creates enhanced preservation through the periodic cycling and scavenging of essential nutrients. Usually, a combination of these factors results in the accumulation of enough OM to produce these black shales. This research shows the relationships between trace metal data and the environment of deposition of several cores taken along the eastern side of the Cincinnati Arch in the central Appalachian Basin. Whereas the indices do not all agree in every instance across the breadth of the study area, analyzed together a predominant environment of deposition has been inferred for the shales. The Sunbury Shale and upper part of the Cleveland Member of the Ohio Shale were deposited under euxinic conditions, the lower part of the Cleveland Member was likely euxinic in the northern study region and anoxic throughout the central and southern study areas, whereas the Huron Member of the Ohio Shale was deposited under a range of conditions, from oxic, to dysoxic, to anoxic.

The temperature record from the Antarctic Peninsula (AP) shows a warming trend 3°C greater than that of the Antarctic continent (Vaughan, et al., 2003). The LARsen Ice Shelf System, Antarctica (LARISSA) project was developed as an interdisciplinary collaboration to understand the impacts of global climate change on the ice shelf systems of the Peninsula. The 2010 LARISSA cruise to the western AP margin collected the two marine sediment cores from the mouth of Barilari Bay used for this thesis, Jumbo Piston Core (JPC) 127 and Jumbo Kasten Core (JKC) 55. The 77 sediment samples collected at 10 cm intervals were sieved at 63 microns to retain foraminiferal tests, identified to the species level. The 35 most abundant foraminifera species were grouped into five assemblages with one outlier species through Hierarchical Cluster Analysis (HCA), predominantly grouped by calcareous and agglutinated foraminifera. The Principal Component Analysis (PCA) yielded two principal components, which accounted for 81.5% of the variability within the data, correlated to the species Fursenkoina spp. and Bulimina aculeata. The base of this core was found to be nearly 8000 calibrated years before present (cal. yr. BP) through radiocarbon dating of the foraminiferal tests. The PCA results were correlated with the magnetic susceptibility down core, producing a timeline of four distinct zones in the mid- to late Holocene at the outer Barilari Bay core site. The earliest zone indicated stable cold bay waters, followed by a drastic change with the incursion of warmer Circumpolar Deep Water (CDW) onto the continental shelf. The third zone of this study illustrated a period of fluctuation between the cold bay waters and the CDW, interrupted by the Little Ice Age when the ice shelf in Barilari Bay extended to the mouth of the bay. The most recent zone depicts the past 200 years of melting ice shelves and the resulting increase in primary productivity observed in the bays of the western AP, discernable from the diatom, foraminifera, and sedimentological record. This description of the benthic foraminiferal record in outer Barilari Bay increases the understanding of the timing of events in the mid- to late Holocene and will serve as a correlation to other paleoclimate proxies from the LARISSA project.

Peatlands in Southern South America (SSA), in the path of the Southern Westerly Wind belt (SWW), offer the potential of reliable palaeoclimate archives. This investigation aimed to test the late-Holocene climate signal related to variability of the SWW. Three sites were investigated: San Juan and Karukinka bog, southernmost Chile and San Carlos, a Sphagnum dominated bog, discovered in the Falkland Islands, to form a regional comparison. A multi-proxy approach was used, combining both palaeoecological and stable isotopic methods. At one site, Karukinka, intra-site replicability was tested across three profiles located along a microtopographical gradient. A low number of statistically significant correlations between proxies were evident. KAR-EM-1, the low-hummock profile, displayed the highest number of significant correlations, suggesting an optimal coring location. Chronological uncertainty in the high-hummock profile, KAR-EM-3, was the focus of discussion. Intra-site replicability between the palaeoecological records was improved by plotting the records against a ‘master chronology’, from the mid-hummock profile, KAR-EM-2, assuming a synchronous acrotelm-catotelm boundary across the profiles. The testate amoeba inferred depth to water table (WTD) reconstructions offered the highest intra-site coherence, while the stable isotope records suggested generally poor intra-site replicability. A semi-quantitative method of intra-site comparison was carried out which resulted in a number of climate scenarios. The inter-site comparison assessed correlations between the records from the three sites. A lack of significant correlations between the sites may have been due to regional climate variations and differences in the temporal resolution of the records. Robust climatic inferences were limited to the last 300 years. The WTD reconstructions displayed the highest inter-site coherence and suggested a drying trend after AD 1930 due to a southerly shift of the SWW. Late-Holocene climate variability was inferred from the palaeoecological records from Karukinka. Two periods were identified: a MCA period of generally wetter conditions (AD 750-1100) and a LIA period of overall drier conditions (~AD 1100-1900) during a southerly and northerly shifted SWW respectively, driven by solar variability and polar cell strengthening.