Noncommutative Toda Chains, Hankel Quasideterminants And Painlev'e II Equation

We construct solutions of an infinite Toda system and an analogue of the Painlev'e II equation over noncommutative differential division rings in terms of quasideterminants of Hankel matrices.Comment: 16 pp; final revised version, will appear in J.Phys. A, minor changes (typos corrected following the Referee's List, aknowledgements and a new reference added

Aircraft Wake RCS Measurement

A series of multi-frequency radar measurements of aircraft wakes at altitudes of 5,000 to 25,00 ft. were performed at Kwajalein, R.M.I., in May and June of 1990. Two aircraft were tested, a Learjet 35 and a Lockheed C-5A. The cross-section of the wake of the Learjet was too small for detection at Kwajalein. The wake of the C-5A, although also very small, was detected and measured at VHF, UHF, L-, S-, and C-bands, at distances behind the aircraft ranging from about one hundred meters to tens of kilometers. The data suggest that the mechanism by which aircraft wakes have detectable radar signatures is, contrary to previous expectations, unrelated to engine exhaust but instead due to turbulent mixing by the wake vortices of pre-existing index of refraction gradients in the ambient atmosphere. These measurements were of necessity performed with extremely powerful and sensitive instrumentation radars, and the wake cross-section is too small for most practical applications

Market Efficiency after the Financial Crisis: It's Still a Matter of Information Costs

Compared to the worldwide financial carnage that followed the Subprime Crisis of 2007–2008, it may seem of small consequence that it is also said to have demonstrated the bankruptcy of an academic financial institution: the Efficient Capital Market Hypothesis (“ECMH”). Two things make this encounter between theory and seemingly inconvenient facts of consequence. First, the ECMH had moved beyond academia, fueling decades of a deregulatory agenda. Second, when economic theory moves from academics to policy, it also enters the realm of politics, and is inevitably refashioned to serve the goals of political argument. This happened starkly with the ECMH. It was subject to its own bubble—as a result of politics, it expanded from a narrow but important academic theory about the informational underpinnings of market prices to a broad ideological preference for market outcomes over even measured regulation. In this Article we examine the Subprime Crisis as a vehicle to return the ECMH to its information cost roots that support a more modest but sensible regulatory policy. In particular, we argue that the ECMH addresses informational efficiency, which is a relative, not an absolute measure. This focus on informational efficiency leads to a more focused understanding of what went wrong in 2007–2008. Yet informational efficiency is related to fundamental efficiency—if all information relevant to determining a security’s fundamental value is publicly available and the mechanisms by which that information comes to be reflected in the security’s market price operate without friction, fundamental and informational efficiency coincide. But where all value-relevant information is not publicly available and/or the mechanisms of market efficiency operate with frictions, the coincidence is an empirical question both as to the information efficiency of prices and their relation to fundamental value. Properly framing market efficiency focuses our attention on the frictions that drive a wedge between relative efficiency and efficiency under perfect market conditions. So framed, relative efficiency is a diagnostic tool that identifies the information costs and structural barriers that reduce price efficiency which, in turn, provides part of a realistic regulatory strategy. While it will not prevent future crises, improving the mechanisms of market efficiency will make prices more efficient, frictions more transparent, and the influence of politics on public agencies more observable, which may allow us to catch the next problem earlier. Recall that on September 8, 2008, the Congressional Budget Office publicly stated its uncertainty about whether there would be a recession and predicted 1.5 percent growth in 2009. Eight days later, Lehman Brothers had failed, and AIG was being nationalized

Building the field of health policy and systems research: framing the questions.

In the first of a series of articles addressing the current challenges and opportunities for the development of Health Policy & Systems Research (HPSR), Kabir Sheikh and colleagues lay out the main questions vexing the field

Business Lawyers and Value Creation for Clients

This Symposium marks an important milestone in legal scholarship and education: The spotlight falls on business lawyers for a change. Ten years ago, when one of us first wrote about what business lawyers really do, no one had devoted much attention to this part of the profession. In his broadside against lawyers, Derek Bok, then President of Harvard University and formerly dean of its law school, reserved his invective for litigators and the litigation process. Business lawyers captured the attention of very few critics; even on the unusual occasion when we were noticed, the criticism was at least funny. If the litigators got Shakespeare\u27s incitement to legacide, we got Kurt Vonnegut. Some of you may remember Vonnegut\u27s primer on the lawyer as transaction cost engineer, in which a popular law professor tells his students that to get ahead in the practice of law a lawyer should be looking for situations where large amounts of money are about to change hands. Give Vonnegut credit he saw the central importance of a transactional focus only a few years after Coase. Vonnegut goes on: In every big transaction [the professor said], there is a magic moment during which a man has surrendered a treasure, and during which the man who is due to receive it has not yet done so. An alert lawyer will make that moment his own, possessing the treasure for a magic microsecond, taking a little of it, passing it on. If the man who is to receive the treasure is unused to wealth, has an inferiority complex and shapeless feelings of guilt, as most people do, the lawyer can often take as much as half the bundle, and still receive the recipient\u27s blubbering thanks

Disputing through Agents: Cooperation and Conflict between Lawyers in Litigation

Do lawyers facilitate dispute resolution or do they instead exacerbate conflict and pose a barrier to the efficient resolution of disputes? A distinctive characteristic of our formal mechanisms of conflict resolution is that clients carry on their disputes through lawyers. Yet, at a time when the role of lawyers in dispute resolution has captured not only public but political attention, social scientists have remained largely uninterested in the influence of lawyers on the disputing process. This is not to say that academics have ignored the growth in civil litigation in the United States. Economists have developed an extensive literature that models one or another aspect of the litigation and settlement process. But the economic literature, with rare exceptions, shares a troublesome feature. Almost by convention, litigation is modeled as a two-person game between principals, thereby abstracting away the legal system's central institutional characteristic-litigation is carried out by agents