The Satisfiability Threshold for a Seemingly Intractable Random Constraint Satisfaction Problem

We determine the exact threshold of satisfiability for random instances of a particular NP-complete constraint satisfaction problem (CSP). This is the first random CSP model for which we have determined a precise linear satisfiability threshold, and for which random instances with density near that threshold appear to be computationally difficult. More formally, it is the first random CSP model for which the satisfiability threshold is known and which shares the following characteristics with random k-SAT for k >= 3. The problem is NP-complete, the satisfiability threshold occurs when there is a linear number of clauses, and a uniformly random instance with a linear number of clauses asymptotically almost surely has exponential resolution complexity.Comment: This is the long version of a paper that will be published in the SIAM Journal on Discrete Mathematics. This long version includes an appendix and a computer program. The contents of the paper are unchanged in the latest version. The format of the arxiv submission was changed so that the computer program will appear as an ancillary file. Some comments in the computer program were update

A Long Term Perspective on the Euro

This essay will evaluate the experience of the first decade of EMU and the euro in historical perspective. It will ground the establishment of EMU and the euro in the context of the history of international monetary cooperation and of monetary unions. A discussion of the origins, key operating characteristics and problems encountered by earlier monetary arrangements will serve as a backdrop for an evaluation of the euro's performance and challenges in future decades. The essay will develop and expand upon the following three themes: 1. Lessons from the evolution of past monetary unions for EMU; 2. Fiscal policy arrangements for EMU in historical perspective; 3. Challenges facing EMU. The first two take an historical perspective. The third looks to the future.Economic and Monetary Union, euro, economic history, international monetary system, history of monetary unions, EMU, Bordo, James

The International Monetary Fund: Its Present Role in Historical Perspective

In this paper we describe what the IMF is and what it does. We consider its origins as the guardian of the Bretton Woods adjustable peg exchange rate system and financier of temporary current account deficits for advanced countries, to its present primary roles as development financier and crisis manager for the emerging world. We consider the externalities or market failures that the IMF is believed by many to correct and the public goods that the IMF provides. Critics of the IMF downplay the extent of market failure and the scope of public goods provided. They attach greater importance to market solutions. We consider their views as well. We conclude with a discussion of the case for reform in the light of historical experience.

The Adam Klug Memorial Lecture: Haberler versus Nurkse: The Case for Floating Exchange Rates as an Alternative to Bretton Woods?

From the perspective of the late 1930s and 1940s the dominant view was that the inter-war currency experience was a financial disaster. The view is perfectly encapsulated in the League of Nations' publication The Inter-war Currency Experience, the bulk of which was written by Ragnar Nurkse and published in 1944. It was also the view behind the Keynes and White plans for international monetary reform, which culminated in the Bretton Woods conference and the establishment of the adjustable peg par value system buttressed by capital controls. An alternative view to Nurkse was posited by Gottfried Haberler in Prosperity and Depression, also commissioned by the League of Nations and published in 1937. In Prosperity and Depression Haberler made a strong intellectual case for floating exchange rates as a mechanism to insulate countries from the transmission of booms and depressions. In this paper we consider the views of Nurkse and Haberler on fixed and floating exchange rates and consider why Haberler's approach was not taken seriously until 1950s. Our main conclusion is that Haberler himself failed to offer a sufficiently clear blueprint for his approach at the time, although he did come to it by 1953. Moreover his views were counter to the ascending Keynesian paradigm.

Swiss Exchange Rate Policy in the 1930s. Was the Delay in Devaluation Too High a Price to Pay for Conservatism?

In this paper we examine the experience of Switzerland’s devaluation in 1936. The Swiss case is of interest because Switzerland was a key member of the gold bloc, and much of the modern academic literature on the Great Depression tries to explain why Switzerland and the other gold bloc countries, France, and the Netherlands, remained on the gold standard until the bitter end. We ask the following questions: what were the issues at stake in the political debate? What was the cost to Switzerland of the delay in the franc devaluation? What would have been the costs and benefits of an earlier exchange rate policy? More specifically, what would have happened if Switzerland had either joined the British and devalued in September 1931, or followed the United States in April 1933? To answer these questions we construct a simple open economy macro model of the interwar Swiss economy. On the basis of this model we then posit counterfactual scenarios of alternative exchange rate pegs in 1931 and 1933. Our simulations clearly show a significant and large increase in real economic activity. If Switzerland had devalued with Britain in 1931, the output level in 1935 would have been some 18 per cent higher than it actually was in that year. If Switzerland had waited until 1933 to devalue, the improvement would have been about 15 per cent higher. The reasons Switzerland did not devalue earlier reflected in part a conservatism in policy making as a result of the difficulty of making exchange rate policy in a democratic setting and in part the consequence of a political economy which favored the fractionalization of different interest groups.

Design and modelling of SOI-based solar thermoelectric generators

In this work, solar micro-thermoelectric generators are designed with a lens concentrating solar radiation onto the membrane of a thermoelectric generator (TEG). By focusing solar radiation, the input heat flux increases; leading to an increase in the temperature gradient across the device. Consequently, a significant improvement in the device efficiency can be achieved. The TEG design involves the use of the SOI wafer's device layer as the first thermoelement and aluminum as the second thermoelement. Isolation trenches are also added to the design for electrical insulation. Heat transfer simulations in COMSOL are performed to verify the viability of the proposed system and an analytical model based on energy balance and heat transfer equations is developed to investigate the performance of solar TEGs with varying geometries, lens parameters, and external conditions. It is found that efficiency is improved by increasing both the concentration factor and the absorptance of the TEG membran

Interview with Harold A. Dunkelberger, July 29, 1999

The first of two interviews, Harold A. Dunkelberger, a student and professor at Gettysburg College, was interviewed on July 29, 1999 by Michael J. Birkner & David Hedrick. He graduated with the class of 1936, and discusses his experience as a student of English at Gettysburg and his time at the Gettysburg Seminary. Length of Interview: 87 minutes Collection Note: This oral history was selected from the Oral History Collection maintained by Special Collections & College Archives. Transcripts are available for browsing in the Special Collections Reading Room, 4th floor, Musselman Library. GettDigital contains the complete listing of oral histories done from 1978 to the present. To view this list and to access selected digital versions please visit -- http://gettysburg.cdmhost.com/cdm/landingpage/collection/p16274coll

Tall claims : mortality selection and the height of children

Data from three rounds of nationally representative health surveys in India are used to assess the impact of selective mortality on children’s anthropometrics. The nutritional status of the child population was simulated under the counterfactual scenario that all children who died in the first three years of life were alive at the time of measurement. The simulations demonstrate that the difference in anthropometrics due to selective mortality would be large only if there were very large differences in anthropometrics between the children who died and those who survived. Differences of this size are not substantiated by the research on the degree of association between mortality and malnutrition. The study shows that although mortality risk is higher among malnourished children, selective mortality has only a minor impact on the measured nutritional status of children or on that status distinguished by gender.Health Monitoring&Evaluation,Population Policies,Youth and Governance,Adolescent Health,Early Child and Children's Health

Velocity-resolved observations of water in Comet Halley

High resolution (lambda/delta lambda approx. = 3 x 10 to the 5th power) near-infrared observations of H2O emission from Comet Halley were acquired at the time of maximum post-perihelion geocentric Doppler shift. The observed widths and absolute positions of the H2O line profiles reveal characteristics of the molecular velocity field in the coma. These results support H2O outflow from a Sun-lit hemisphere or the entire nucleus, but not from a single, narrow jet emanating from the nucleus. The measured pre- and post-perihelion outflow velocities were 0.9 + or - 0.2 and 1.4 + or - 0.2 km/s, respectively. Temporal variations in the kinematic properties of the outflow were inferred from changes in the spectral line shapes. These results are consistent with the release of H2O into the coma from multiple jets