Ultrahigh-Field MRI in Human Ischemic Stroke – a 7 Tesla Study

INTRODUCTION: Magnetic resonance imaging (MRI) using field strengths up to 3 Tesla (T) has proven to be a powerful tool for stroke diagnosis. Recently, ultrahigh-field (UHF) MRI at 7 T has shown relevant diagnostic benefits in imaging of neurological diseases, but its value for stroke imaging has not been investigated yet. We present the first evaluation of a clinically feasible stroke imaging protocol at 7 T. For comparison an established stroke imaging protocol was applied at 3 T. METHODS: In a prospective imaging study seven patients with subacute and chronic stroke were included. Imaging at 3 T was immediately followed by 7 T imaging. Both protocols included T1-weighted 3D Magnetization-Prepared Rapid-Acquired Gradient-Echo (3D-MPRAGE), T2-weighted 2D Fluid Attenuated Inversion Recovery (2D-FLAIR), T2-weighted 2D Fluid Attenuated Inversion Recovery (2D-T2-TSE), T2* weighted 2D Fast Low Angle Shot Gradient Echo (2D-HemoFLASH) and 3D Time-of-Flight angiography (3D-TOF). RESULTS: The diagnostic information relevant for clinical stroke imaging obtained at 3 T was equally available at 7 T. Higher spatial resolution at 7 T revealed more anatomical details precisely depicting ischemic lesions and periinfarct alterations. A clear benefit in anatomical resolution was also demonstrated for vessel imaging at 7 T. RF power deposition constraints induced scan time prolongation and reduced brain coverage for 2D-FLAIR, 2D-T2-TSE and 3D-TOF at 7 T versus 3 T. CONCLUSIONS: The potential of 7 T MRI for human stroke imaging is shown. Our pilot study encourages a further evaluation of the diagnostic benefit of stroke imaging at 7 T in a larger study

Discutindo a educação ambiental no cotidiano escolar: desenvolvimento de projetos na escola formação inicial e continuada de professores

A presente pesquisa buscou discutir como a Educação Ambiental (EA) vem sendo trabalhada, no Ensino Fundamental e como os docentes desta escola compreendem e vem inserindo a EA no cotidiano escolar., em uma escola estadual do município de Tangará da Serra/MT, Brasil. Para tanto, realizou-se entrevistas com os professores que fazem parte de um projeto interdisciplinar de EA na escola pesquisada. Verificou-se que o projeto da escola não vem conseguindo alcançar os objetivos propostos por: desconhecimento do mesmo, pelos professores; formação deficiente dos professores, não entendimento da EA como processo de ensino-aprendizagem, falta de recursos didáticos, planejamento inadequado das atividades. A partir dessa constatação, procurou-se debater a impossibilidade de tratar do tema fora do trabalho interdisciplinar, bem como, e principalmente, a importância de um estudo mais aprofundado de EA, vinculando teoria e prática, tanto na formação docente, como em projetos escolares, a fim de fugir do tradicional vínculo “EA e ecologia, lixo e horta”.Facultad de Humanidades y Ciencias de la Educació

Essays on corporate law and economics

This dissertation focuses on how certain changes in the legal and institutional environment for publicly traded corporations in the United States have impacted shareholder wealth and firm performance. The first chapter focuses the legalization of so-called forum bylaws. By adopting such bylaws, corporate boards can specify an exclusive forum for shareholder lawsuits against the corporation and its managers. Thus, corporate boards are able to put an end to multi-district litigation and forum shopping by shareholder plaintiffs. Starting in 2013, various U.S. states adopted case law or statutes permitting firms to adopt forum bylaws. Using an event study approach, I provide evidence consistent with the idea that the impact of legalizing forum bylaws depends on the state of incorporation. Both the Boilermakers decision that embraced the legality of forum bylaws under Delaware law and subsequent judgments enforcing such bylaws were accompanied by positive abnormal returns for Delaware firms. By contrast, the adoption of forum bylaw legislation in New Jersey was associated with negative abnormal returns for New Jersey firms. Moreover, when the American Bar Association announced its intention to change the Model Business Corporation Act to allow forum bylaws, firms incorporated in states that were most likely to copy that change experienced statistically significant negative abnormal returns. These findings are consistent with the hypothesis that the legalization of forum bylaws benefits shareholders of Delaware firms, but may harm shareholders of firms incorporated in other states. A possible explanation is that Delaware has a particularly excellent court for corporate litigation, whereas most other states lack that advantage. The second chapter focuses on the question of whether giving corporations access to high-quality courts for litigating their internal affairs benefits shareholder wealth and firm performance. To shed some light on this question, this paper focuses on the creation of business courts in various states between 1992 and 2017. Relying on an event-study design, I find that stock prices of firms that are both headquartered and incorporated in states creating business courts experience statistically significant abnormal returns of 1.2 % at the time that such business courts are created relative to firms that are only headquartered in the pertinent state, but incorporated elsewhere. Notably, these results are driven by the creation of business courts in those states, whose general court systems fare poorly in court quality rankings. To explore the long-term relationship between business courts and firm performance, I employ a difference-in-differences approach and find that, controlling for headquarters-state year fixed effects, the existence of a business court is associated with a higher return on assets, a higher return on sales, and an increased likelihood for firms to become the target in a merger with positive abnormal returns for the target shareholders. Finally, using both probit and linear probability models, I find that firms are more likely to incorporate locally if their home state has a business court. The third chapter focuses on the emerging practice among courts to defer to Delaware precedents in deciding corporate law cases. Delaware is home to more than half of all public corporations, and its market share among initial public offerings is even higher. Not surprisingly, therefore, an extensive body of literature is dedicated to exploring the causes and consequences of Delaware's preeminence as a state of incorporation. There exists, however, a second and largely ignored dimension in which Delaware has come to dominate U.S. corporate law: the common law process. Courts in numerous other states now accord Delaware case law a previously unheard-of level of deference: many state judiciaries have declared explicitly that they will look to Delaware cases in deciding open legal questions. In this paper, I undertake an empirical analysis of Delaware's impact on the corporate common law of other states. Using a hand-collected dataset of state and federal cases, I gain a number of important insights. First, deference to Delaware may be driven in part by functional considerations. States that have based their law on the Model Business Corporation Act (MBCA) and can therefore rely on case law from other MBCA states are less likely to defer to Delaware precedents. Second, firms are more likely to incorporate locally if their home states' courts look to Delaware precedents in corporate law matters. Third, stocks of corporations that are incorporated in the deferring state tend to experience positive abnormal returns at the time of court decisions that introduce the principle of deferring to Delaware case law. Fourth, there is some, albeit mixed, evidence that that stock price reaction is substantially stronger for those firms where agency conflicts between managers and shareholders are more pronounced. This last finding is intuitive in the sense that well-governed firms, if they stood to benefit from the application of Delaware case law, might already have (re)incorporated in Delaware.Economic

Globalizing Commercial Litigation

The world’s nations vary widely in the quality of their judicial systems. In some jurisdictions, the courts resolve commercial disputes quickly, fairly, and economically. In others, they are slow, inefficient, incompetent, biased, or corrupt. These differences are important not just for litigants, but for nations as a whole: effective courts are important for economic development. A natural implication is that countries with underperforming judiciaries should reform their courts. Yet reform is both difficult and slow. Another way to deal with a dysfunctional court system is for litigants from afflicted nations to have their commercial disputes adjudicated in the courts of other nations that have better-functioning judicial systems. We explore here the promise of such extraterritorial litigation and conclude that it is strong, particularly in light of a communications revolution that is making litigation at a distance increasingly feasible. While available data suggests that the volume of extraterritorial litigation is presently small, a set of basic legal reforms could eventually change that situation dramatically. To create incentives for adopting those reforms, it is essential to provide jurisdictions with a strong incentive to attract foreign litigants. The best way to achieve this is to allow jurisdictions to impose higher court fees in cases between foreign litigants that do not have substantial ties to the forum state. This may require an important adjustment in the legal culture. But only by abandoning formal equality in court fees is it likely that real global equality in access to judicial services can be accomplished

FACT facilitates chromatin transcription by RNA polymerases I and III

Efficient transcription elongation from a chromatin template requires RNA polymerases (Pols) to negotiate nucleosomes. Our biochemical analyses demonstrate that RNA Pol I can transcribe through nucleosome templates and that this requires structural rearrangement of the nucleosomal core particle. The subunits of the histone chaperone FACT (facilitates chromatin transcription), SSRP1 and Spt16, co-purify and co-immunoprecipitate with mammalian Pol I complexes. In cells, SSRP1 is detectable at the rRNA gene repeats. Crucially, siRNA-mediated repression of FACT subunit expression in cells results in a significant reduction in 47S pre-rRNA levels, whereas synthesis of the first 40 nt of the rRNA is not affected, implying that FACT is important for Pol I transcription elongation through chromatin. FACT also associates with RNA Pol III complexes, is present at the chromatin of genes transcribed by Pol III and facilitates their transcription in cells. Our findings indicate that, beyond the established role in Pol II transcription, FACT has physiological functions in chromatin transcription by all three nuclear RNA Pols. Our data also imply that local chromatin dynamics influence transcription of the active rRNA genes by Pol I and of Pol III-transcribed genes