An update on the middle levels problem

The middle levels problem is to find a Hamilton cycle in the middle levels, M_{2k+1}, of the Hasse diagram of B_{2k+1} (the partially ordered set of subsets of a 2k+1-element set ordered by inclusion). Previously, the best result was that M_{2k+1} is Hamiltonian for all positive k through k=15. In this note we announce that M_{33} and M_{35} have Hamilton cycles. The result was achieved by an algorithmic improvement that made it possible to find a Hamilton path in a reduced graph of complementary necklace pairs having 129,644,790 vertices, using a 64-bit personal computer.Comment: 11 pages, 5 figure

Macroeconomic Shocks, Job Security and Health: Evidence from the Mining Industry

How do exogenous changes in the macroeconomic environment affect workers’ perceived job security, and consequently, their mental and physical health? To answer this question, we exploit variation in world commodity prices over the period 2001-17 and analyse panel data that includes detailed classifications of mining workers. We find that commodity price increases cause increases in perceived job security, which in turn, significantly and substantively improve the mental health of workers. In contrast, we find no effects on physical health. Our results imply that the estimated welfare costs of recessions are much larger when the effects of job insecurity, and not only unemployment, are considered

Development of user guidelines for ECAS display design, volume 1

Experiment computer application software (ECAS) display design and command usage guidelines were developed, which if followed by spacelab experiments, would standardize methods and techniques for data presentation and commanding via ECAS. These guidelines would provide some commonality among experiments which would enhance crew training and flight operations. The guidelines are applicable to all onboard experiment displays, whether allocated by ECAS or a dedicated experiment processor. A brief description of the spacelab data display system characteristics and of the services provided by the experiment computer operating system is included. Guidelines concerning data presentation and layout of alphanumeric and graphic information are presented along with guidelines concerning keyboard commanding and command feedback