Underwater Hacker Missile Wars: A Cryptography and Engineering Contest

For a recent student conference, the authors developed a day-long design problem and competition suitable for engineering, mathematics and science undergraduates. The competition included a cryptography problem, for which a workshop was run during the conference. This paper describes the competition, focusing on the cryptography problem and the workshop. Notes from the workshop and code for the computer programs are made available via the Internet. The results of a personal self-evaluation (PSE) are described.Comment: 11 pages, 3 figures, uses amsrefs.sty v2.0 and cryptologiabib.sty (included); to appear in Cryptologi

Chandra and XMM-Newton Observations of the Double Cluster Abell 1758

Abell 1758 was classified as a single rich cluster of galaxies by Abell, but a ROSAT observation showed that this system consists of two distinct clusters (A1758N and A1758S) separated by approximately 8\arcmin (a projected separation of 2 Mpc in the rest frame of the clusters). Only a few galaxy redshifts have been published for these two clusters, but the redshift of the Fe lines in the Chandra and XMM-Newton spectra shows that the recessional velocities of A1758N and A1758S are within 2,100 km s$^{-1}$. Thus, these two clusters most likely form a gravitationally bound system, but our imaging and spectroscopic analyses of the X-ray data do not reveal any sign of interaction between the two clusters. The Chandra and XMM-Newton observations show that A1758N and A1758S are both undergoing major mergers. A1758N is in the late stages of a large impact parameter merger between two 7 keV clusters. The two remnant cores have a projected separation of 800 kpc. Based on the measured pressure jumps preceding the two cores, they are receding from one another at less than 1,600 km s$^{-1}$. The two cores are surrounded by hotter gas ($\mathrm{kT}=9$--12 keV) that was probably shock heated during the early stages of the merger. The gas entropy in the two remnant cores is comparable with the central entropy observed in dynamically relaxed clusters, indicating that the merger-induced shocks stalled as they tried to penetrate the high pressure cores of the two merging systems.Each core also has a wake of low entropy gas indicating that this gas was ram pressure stripped without being strongly shocked (abridged). (A copy of the paper with higher resolution images is available at http://asc.harvard.edu/~lpd/a1758.ps).Comment: paper plus 13 figure

Responding to God\u27s Guidance

Interview by Joshua Shuart and Laurence Weinstein of Craig Hoekenga, CEO of Microboard Processing, Inc. Craig Hoekenga is CEO of Microboard Processing, Inc. (MPI), a very successful subcontract electronics manufacturing company located in Seymour, Connecticut. There are many reasons why Hoekenga would stand out in any gathering of CEOs, but one of the most arresting reasons would be that Hoekenga credits his success to God and considers MPI a “Christian business.” The New England Journal of Entrepreneurhip editors started with a plant tour and then caught up with Hoekenga in his office