Últimos itens adicionados do Acervo: Harvard University

A Universidade de Harvard (em inglês: Harvard University) é uma universidade privada membro da Ivy League, localizada em Cambridge, Massachusetts, Estados Unidos, e cuja história, influência e riqueza tornam-a uma das mais prestigiadas universidades do mundo.

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TIL: a Type-directed Optimizing Compiler for ML

Tarditi, David; Harper, Robert; Morrisett, John Gregory; Cheng, Perry; Stone, Christopher; Lee, Peter
Fonte: Association for Computing Machinery Publicador: Association for Computing Machinery
EN_US
Engineering and Applied Sciences

Typed Closure Conversion

Harper, Robert; Minamide, Yasuhiko; Morrisett, Greg
Fonte: Association for Computing Machinery Publicador: Association for Computing Machinery
Tipo: Conference Paper
EN_US
Closure conversion is a program transformation used by compilers to separate code from data. Previous accounts of closure conversion use only untyped target languages. Recent studies show that translating to typed target languages is a useful methodology for building compilers, because a compiler can use the types to implement efficient data representations, calling conventions, and tag-free garbage collection. Furthermore, type-based translations facilitate security and debugging through automatic type checking, as well as correctness arguments through the method of logical relations. We present closure conversion as a type-directed, and type preserving translation for both the simply-typed and the polymorphic λ--calculus. Our translations are based on a simple "closures as objects" principle: higher-order functions are viewed as objects consisting of a single method (the code) and a single instance variable (the environment). In the simply-typed case, the Pierce-Turner model of object typing where objects are packages of existential type suffices. In the polymorphic case, more careful tracking of type sharing is required. We exploit a variant of the Harper-Lillibridge "translucent type" formalism to characterize the types of polymorphic closures.; Engineering and Applied Sciences

The Prisoner's Dilemma: The History, Ethical Dimensions, and Evolving Regulatory Landscape of Clinical Trials on Inmates

Fitzpatrick, Caitlin Noelle
Fonte: Harvard University Publicador: Harvard University
Tipo: Paper (for course/seminar/workshop)
The history of research on prisoners in the United States is marred with a shameful past of abuse and coercion. With the development of research ethics arising from the Nuremberg Code and the Belmont Report, a critical light was shone on these oppressive practices. In 1974, the Department of Health and Human Services commissioned a group to investigate the conditions under which prisoners were used a research subjects and to formulate recommendations to guide clinicians in the future. The results of this Commission Report paved the way for Subpart C of the HHS regulations, which classifies prisoners as a vulnerable population and created a de facto ban on the use of inmates in any research study that received federal funding. What made this situation particularly noteworthy was the position of the FDA following this eventful change in regulation. Initially, the FDA proposed a rule similar to that of HHS which would have effectively barred the use of prisoners in all clinical research on FDAregulated products, even that which was privately funded. This proposal was met with staunch resistance, and a lawsuit filed by prisoners and a pharmaceutical company claimed that their constitutional rights would be violated by this de facto ban. The FDA eventually settled the case...

Solving Problems in an Uncertain World

Shieber, Stuart M.
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
EN_US
The issue of problem solving in the context of incomplete or inconsistent information is a precursor to designing multiple agent planning systems. We present some general principles of planning and problem-solving in uncertainty, and instantiate these principles in a problem-solving system based on the NOAH planning system. The new NOAH system, working on the blocks world as a test domain, plans in certainty with the same efficacy as the original system, but can also handle a large class of errors caused by inconsistent or incomplete information.

Foreword: Blue State Federalism at the Crossroads

Barron, David J.
Fonte: Harvard Law School Publicador: Harvard Law School
Tipo: Artigo de Revista Científica
EN_US

Law of Policy of Targeted Killing

Blum, Gabriella; Heymann, Philip B.
Fonte: Harvard Law School Publicador: Harvard Law School
Tipo: Artigo de Revista Científica
EN_US
This is a chapter from our forthcoming book, 'Laws, Outlaws, and Terrorists: Lessons from the War on Terrorism', (MIT Press, September 2010). This chapter addresses the legal, ethical, and strategic aspects of targeted killings as a counterterrorism measure, drawing on the American and Israeli experience. We argue that since terrorism is neither a traditional war nor a traditional crime, its non-traditional nature must affect how, where, and when we employ targeted killings. Specifically, we argue that whether one begins with a law enforcement model or a war model in mind, the ultimate contours of justifiable targeted killings are very similar under either paradigm.

Too Big to Fail Banks: Examining the 'How' of Breaking Up

Singh, Aditi
Fonte: Harvard University Publicador: Harvard University
Tipo: Paper (for course/seminar/workshop)
The newfound understanding that systemic risk is the central problem of financial regulation, has informed both institutional and regulatory responses to the global financial crisis. At the forefront of the systemic risk debate is the problem of too-big-to-fail, which has become increasingly intractable as a result of little analytical certainty and myriad policy options. Dodd Frank proposes several structural, behavioral and conduct based regulatory tools to counteract the financial industry’s incentives to assume significant risks and to provide a solution to the systemic risk problem. This article examines the policy solution of limiting the size of too-big-to-fail banks, specifically the issue of breaking up a bank that exceeds a certain size threshold. Breaking up of banks is an idea that has started to gain increasing traction from politicians, regulators and financial analysts alike. However, the debate so far has failed to address fundamental questions relating to how the break up is to be achieved. This article attempts to venture into the hitherto unexplored territory of the manner of breaking up of a too-big-to-fail bank, without examining the merits of whether the breakup itself is advisable or not. The article develops a three-pronged approach to address this question. First...

Net Neutrality as Diplomacy

Zittrain, Jonathan L.
Fonte: Yale Law School Publicador: Yale Law School
Tipo: Artigo de Revista Científica
EN_US
Popular imagination holds that the turf of a state’s foreign embassy is a little patch of its homeland. Enter the American Embassy in Beijing and you are in the United States. Indeed, in many contexts—such as resistance to search and seizure by a host country’s authorities—there is an inviolability to diplomatic outposts. These arrangements have been central to diplomacy for decades so that diplomats can perform their work without fear of harassment and coercion.

The 'Antidirector Rights Index' Revisited

Spamann, Holger
Fonte: Oxford University Press (OUP) Publicador: Oxford University Press (OUP)
Tipo: Artigo de Revista Científica
EN_US
The “antidirector rights index” has been used as a measure of shareholder protection in over a hundred articles since it was introduced by La Porta et al. (“Law and Finance.” 1998, Journal of Political Economy 106:1113–55). A thorough reexamination of the legal data, however, leads to corrections for thirty-three of the forty-six countries analyzed. The correlation between corrected and original values is only 0.53. Consequently, many empirical results established using the original index may not be replicable with corrected values. In particular, the corrected index fails to support three widely influential claims: that shareholder protection is higher in common than in civil law countries; that shareholder protection predicts stock market size or ownership dispersion; and that weak corporate governance explains the extent of exchange rate depreciation during the Asian financial crisis of 1997–1998.

Regulating Bankers' Pay

Bebchuk, Lucian Arye; Spamann, Holger
Fonte: Georgetown University Law Center Publicador: Georgetown University Law Center
Tipo: Artigo de Revista Científica
EN_US
This paper seeks to make three contributions to understanding how banks’ executive pay has produced incentives for excessive risk-taking and how such pay should be reformed. First, although there is now wide recognition that pay packages focused excessively on short-term results, we analyze a separate and critical distortion that has received little attention. Equity-based awards, coupled with the capital structure of banks, tie executives’ compensation to a highly levered bet on the value of banks’ assets. Because bank executives expect to share in any gains that might flow to common shareholders, but are insulated from losses that the realization of risks could impose on preferred shareholders, bondholders, depositors, and taxpayers, executives have incentives to give insufficient weight to the downside of risky strategies. Second, we show that corporate governance reforms aimed at aligning the design of executive pay arrangements with the interests of banks’ common shareholders - such as advisory shareholder votes on compensation arrangements, use of restricted stock awards, and increased director oversight and independence -cannot eliminate the identified problem. In fact, the interests of common shareholders could be served by more risk-taking than is socially desirable. Accordingly...

Titles of Nobility: Poverty, Immigration, and Property in a Free and Democratic Society

Singer, Joseph William
Fonte: Association for Law, Property and Society Publicador: Association for Law, Property and Society
EN_US

Mobile App Acceleration via Fine-Grain Offloading to the Cloud

Lin, Chit-Kwan; Kung, H. T.
Fonte: USENIIX Publicador: USENIIX
Tipo: Conference Paper
EN_US
Mobile device hardware can limit the sophistication of mobile applications. One strategy for side-stepping these constraints is to opportunistically offload computations to the cloud, where more capable hardware can do the heavy lifting. We propose a platform that accomplishes this via compressive offloading, a novel application of compressive sensing in a distributed shared memory setting. Our prototype gives up to an order-of-magnitude acceleration and 60% longer battery life to the end user of an example handwriting recognition app. We argue that offloading is beneficial to both end users and cloud providers—the former experiences a performance boost and the latter receives a steady stream of small computations to fill periods of under-utilization. Such workloads, originating from ARM-based mobile devices, are especially well-suited for offloading to emerging ARM-based data centers.; Engineering and Applied Sciences

Suboptimal Institutions but Superior Growth: The Puzzle of China's Economic Boom

Whyte, Martin K.
Fonte: Routledge Publicador: Routledge
Tipo: Monograph or Book
EN_US
Sociology

Don't Let the Truth Get in the Way of a Good Story: An Illustration of Citation Bias in Epidemiologic Research

Kivimäki, Mika; Batty, G. David; Kawachi, Ichiro; Virtanen, Marianna; Singh-Manoux, Archana; Brunner, Eric J.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN_US

Histone Deacetylase Inhibitors Impair the Elimination of HIV-Infected Cells by Cytotoxic T-Lymphocytes

Jones, Richard Brad; O'Connor, Rachel; Mueller, Stefanie; Foley, Maria; Szeto, Gregory L.; Karel, Dan; Lichterfeld, Mathias; Kovacs, Colin; Ostrowski, Mario A.; Trocha, Alicja; Irvine, Darrell J.; Walker, Bruce D.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN_US
Resting memory CD4+ T-cells harboring latent HIV proviruses represent a critical barrier to viral eradication. Histone deacetylase inhibitors (HDACis), such as suberanilohydroxamic acid (SAHA), romidepsin, and panobinostat have been shown to induce HIV expression in these resting cells. Recently, it has been demonstrated that the low levels of viral gene expression induced by a candidate HDACi may be insufficient to cause the death of infected cells by viral cytopathic effects, necessitating their elimination by immune effectors, such as cytotoxic T-lymphocytes (CTL). Here, we study the impact of three HDACis in clinical development on T-cell effector functions. We report two modes of HDACi-induced functional impairment: i) the rapid suppression of cytokine production from viable T-cells induced by all three HDACis ii) the selective death of activated T-cells occurring at later time-points following transient exposures to romidepsin or, to a lesser extent, panobinostat. As a net result of these factors, HDACis impaired CTL-mediated IFN-γ production, as well as the elimination of HIV-infected or peptide-pulsed target cells, both in liquid culture and in collagen matrices. Romidepsin exerted greater inhibition of antiviral function than SAHA or panobinostat over the dose ranges tested. These data suggest that treatment with HDACis to mobilize the latent reservoir could have unintended negative impacts on the effector functions of CTL. This could influence the effectiveness of HDACi-based eradication strategies...

Nonlinear Effects on ENSOʼs Period

Eccles, Fiona; Tziperman, Eli
Fonte: American Meteorological Society Publicador: American Meteorological Society
Tipo: Artigo de Revista Científica
EN_US
The dependence of ENSO’s period on its amplitude is examined using a simple delayed oscillator model. This dependence is first calculated in the strongly nonlinear regime by extracting and analyzing unstable periodic orbits from the chaotic attractor of the model. In this regime, the period is found to decrease with increasing amplitude. Next, the dependence of the period on the amplitude is also calculated analytically and numerically in the weakly nonlinear regime by varying the ocean–atmosphere coupling coefficient. In this case, the period increases with the amplitude. The weakly nonlinear result reflects the dependence of the period on the ocean–atmosphere coupling strength rather than the dependence on the amplitude, while the strongly nonlinear result is the robust take-home message here: the period reduces with increasing amplitude.; Earth and Planetary Sciences

Westerly Wind Bursts: ENSO’s Tail Rather than the Dog?

Eisenman, Ian; Tziperman, Eli; Yu, Lisan
Fonte: American Meteorological Society Publicador: American Meteorological Society
Tipo: Artigo de Revista Científica
EN_US
Westerly wind bursts (WWBs) in the equatorial Pacific occur during the development of most El Niño events and are believed to be a major factor in ENSO’s dynamics. Because of their short time scale, WWBs are normally considered part of a stochastic forcing of ENSO, completely external to the interannual ENSO variability. Recent observational studies, however, suggest that the occurrence and characteristics of WWBs may depend to some extent on the state of ENSO components, implying that WWBs, which force ENSO, are modulated by ENSO itself. Satellite and in situ observations are used here to show that WWBs are significantly more likely to occur when the warm pool is extended eastward. Based on these observations, WWBs are added to an intermediate complexity coupled ocean–atmosphere ENSO model. The representation of WWBs is idealized such that their occurrence is modulated by the warm pool extent. The resulting model run is compared with a run in which the WWBs are stochastically applied. The modulation of WWBs by ENSO results in an enhancement of the slow frequency component of the WWBs. This causes the amplitude of ENSO events forced by modulated WWBs to be twice as large as the amplitude of ENSO events forced by stochastic WWBs with the same amplitude and average frequency. Based on this result...

Factors Affecting ENSO’s Period

MacMynowski, Douglas G.; Tziperman, Eli
Fonte: American Meteorological Society Publicador: American Meteorological Society
Tipo: Artigo de Revista Científica
EN_US
Accurately capturing the observed mean period of ENSO in general circulation models (GCMs) is often challenging, and it is therefore useful to understand which parameters and processes affect this period. A computationally efficient simulation-based approach is used to extract both the dominant eigenvalues and corresponding eigenvectors of the linearized model from the Zebiak–Cane intermediate-complexity model of ENSO without having to directly construct the linearization. The sensitivity of the period to a variety of parameters is examined, including atmosphere–ocean coupling, atmospheric heating parameterization, thermocline depth zonal profile, western boundary reflection coefficient, atmospheric and ocean wave speeds or Rossby radii of deformation, ocean decay time, and the strength of the annual cycle. In addition to the sensitivity information, the spatial structures of the main fields (SST, thermocline thickness, and more) that are involved in period changes are obtained to aid in the physical interpretation of the sensitivities. There are three main time lags that together compose one-half of a model ENSO period: the Rossby-plus-Kelvin wave propagation time for a wind-caused central Pacific disturbance to propagate to the western ocean and back...

Old Irish bé 'woman'

Jasanoff, Jay H.
Fonte: Royal Irish Academy Publicador: Royal Irish Academy
Tipo: Artigo de Revista Científica
EN_US
Linguistics

The Alexander Polynomial of a 3-Manifold and the Thurston Norm on Cohomology

McMullen, Curtis T.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
EN_US
Let M be a connected, compact, orientable 3-manifold with \(b_1(M)>1\), whose boundary (if any) is a union of tori. Our main result is the inequality \({\parallel \phi \parallel}_A \le {\parallel \phi \parallel}_T\) between the Alexander norm on \(H^1(M,\mathbb{Z})\), defined in terms of the Alexander polynomial, and the Thurston norm, defined in terms of the Euler characteristic of embedded surfaces. (A similar result holds when \(b_1(M)=1\).) Using this inequality we determine the Thurston norm for most links with 9 or fewer crossings.; Mathematics