Hydrodynamic Limit for an Hamiltonian System with Boundary Conditions and Conservative Noise

We study the hyperbolic scaling limit for a chain of N coupled anharmonic oscillators. The chain is attached to a point on the left and there is a force (tension) $\tau$ acting on the right. In order to provide good ergodic properties to the system, we perturb the Hamiltonian dynamics with random local exchanges of velocities between the particles, so that momentum and energy are locally conserved. We prove that in the macroscopic limit the distributions of the elongation, momentum and energy, converge to the solution of the Euler system of equations, in the smooth regime.Comment: New deeply revised version. 1 figure adde

Advanced spacecraft thermal control techniques

The problems of rejecting large amounts of heat from spacecraft were studied. Shuttle Space Laboratory heat rejection uses 1 kW for pumps and fans for every 5 kW (thermal) heat rejection. This is rather inefficient, and for future programs more efficient methods were examined. Two advanced systems were studied and compared to the present pumped-loop system. The advanced concepts are the air-cooled semipassive system, which features rejection of a large percentage of the load through the outer skin, and the heat pipe system, which incorporates heat pipes for every thermal control function

Poultry in Motion: A Study of International Trade Finance Practices

This paper analyzes the financing terms that support international trade and sheds light on how and why these arrangements affect trade. Using detailed transaction level data from a U.S. based exporter of frozen and refrigerated food products, primarily poultry, it begins by describing broad patterns about the use of alternative financing terms. These patterns help discipline a model in which the trade finance mode is shaped by the risk that an importer defaults on an exporter and by the possibility that an exporter does not deliver goods as specified in the contract. The empirical results indicate that transactions are more likely to occur on cash in advance or letter of credit terms when the importer is located in a country with weak contractual enforcement and in a country that is further from the exporter. Letters of credit, however, are rarely used by the exporter. As an importer develops a relationship with the exporter, transactions are less likely to occur on terms that require prepayment. During the recent crisis, the exporter was more likely to demand cash in advance terms when transacting with new customers, and customers that traded on cash in advance terms prior to the crisis disproportionately reduced their purchases. These results can be rationalized by the model whenever (i) misbehavior on the part of the exporter is of little concern to importers, and (ii) local banks in importing countries are typically more effective than the exporter in pursuing financial claims against importers.

Facts and Fallacies about U.S. FDI in China

Despite the rapid expansion of U.S.-China trade ties, the increase in U.S. FDI in China, and the expanding amount of economic research exploring these developments, a number of misconceptions distort the popular understanding of U.S. multinationals in China. In this paper, we seek to correct four common misunderstandings by providing a statistical portrait of several aspects of U.S. affiliate activity in the country and placing this activity in its appropriate economic context.

The Comovement of Returns and Investment Within the Multinational Firm

Can financial integration, particularly the cross-border investments of multinational firms, help explain the synchronization of business cycles? This paper presents evidence on the comovement of returns and investment within U.S. multinational firms to address this question. These firms constitute significant fractions of economic output and investment in most large economies, suggesting that they could create significant economic linkages. Aggregate measures of rates of return and investment rates of U.S. multinational firms located in different countries are highly correlated across countries. Firm-level regressions demonstrate that rates of return and investment rates of affiliates are highly correlated with the rates of return and investment of the affiliate's parent and other affiliates within the same parent system, controlling for country and industry factors. The evidence on these interrelationships and the importance of multinationals to local economies suggests that global firms may be an important channel for transmitting economic shocks. This evidence also sheds light on asset pricing puzzles related to the diversification benefits provided by multinational firms.

A Comparison of Algorithms for the Multivariate L1-Median

The L1-median is a robust estimator of multivariate location with good statistical properties. Several algorithms for computing the L1- median are available. Problem speci c algorithms can be used, but also general optimization routines. The aim is to compare dierent algorithms with respect to their precision and runtime. This is pos- sible because all considered algorithms have been implemented in a standardized manner in the open source environment R. In most sit- uations, the algorithm based on the optimization routine NLM (non- linear minimization) clearly outperforms other approaches. Its low computation time makes applications for large and high-dimensional data feasible.Algorithm;Multivariate median;Optimization;Robustness

The Threatened Status of Steller Sea Lions, Eumetopias jubatus, under the Endangered Species Act: Effects on Alaska Groundfish Fisheries Management

In April 1990, the Steller sea lion, Eumetopias jubatus, was listed as threatened under the U.S. Endangered Species Act by emergency action. Competitive interactions with the billion-dollar Alaska commercial groundfish fisheries have been suggested as one of the possible contributing factors to the Steller sea lion population decline. Since the listing, fisheries managers have attempted to address the potential impacts of the groundfish fisheries on Steller sea lion recovery. In this paper, we review pertinent Federal legislation, biological information on the Steller sea lion decline, changes in the Alaska trawl fishery for walleye pollock, Theragra chalcogramma, since the late 1970's, andpossible interactions between fisheries and sea lions. Using three cases, we illustrate how the listing of Steller sea lions has affected Alaska groundfish fisheries through: I) actions taken at the time of listing designed to limit the potential for directhuman-related sea lion mortality, 2) actions addressing spatial and temporal separation of fisheries from sea lions, and 3) introduction of risk-adverse stock assessment methodologies and Steller sea lion conservation considerations directly in the annual quota-setting process. This discussion shows some of the ways that North Pacific groundfish resource managers have begun to explicitly consider the conservation ofmarine mammal and other nontarget species