Naturalness of the Coleman-Glashow Mass Relation in the 1/N_c Expansion: an Update

A new measurement of the Xi^0 mass verifies the accuracy of the Coleman-Glashow relation at the level predicted by the 1/N_c expansion. Values for other baryon isospin mass splittings are updated, and continue to agree with the 1/N_c hierarchy.Comment: 6 pages, revte

Is China ‘Crowding Out’ South African Exports of Manufactures?

This article analyses the impact of Chinese competition on South African manufacturing exports to its major markets in Europe, the United States and Sub-Saharan Africa. The article considers five related research questions. First, are China and South Africa competing with each other in export markets, how extensive is such competition and how is this changing over time? Second, to what extent has Chinese competition led to the displacement of South African exports? Third, in which countries have South African exports been most affected? Fourth, which South African export sectors face the greatest threat from Chinese competition? Finally, how does South Africa's experience compare to that of Brazil, another middle-income country and regional power. We find that competition between South Africa and China increased significantly over the past decade, particularly in African markets. All types of manufactured exports lost ground to China, but the impact is strongest in low-technology products. South African exports have nevertheless increased from 2001 so that ‘crowding out’ should be interpreted in relative terms

The flow field of an underexpanded H2 jet coaxially injected into a hot free or ducted supersonic jet of air or nitrogen

Experimental data obtained in an investigation of the mixing of an underexpanded hydrogen jet in a supersonic flow both with and without combustion are presented. Tests were conducted in a Mach 2 test stream with both air and nitrogen as test media. Total temperature of the test stream was 2170 K, and static exit pressure was about one atmosphere. The static pressure at the exit of the hydrogen injector's Mach 2 nozzle was about two atmospheres. Primary measurements included shadowgraphs and pitot pressure surveys of the flow field. Pitot surveys and wall static pressures were measured for the case where the entire flow was shrouded. The results are compared to similar experimental data and theoretical predictions for the matched pressure case

Quenched Chiral Perturbation Theory for Baryons

We develop quenched chiral perturbation theory for baryons using the graded-symmetry formalism of Bernard and Golterman and calculate non-analytic contributions to the baryon masses coming from quenched chiral loops. The usual term proportional to $m_{q}^{3/2}$ is substantially altered due to the cancellation of diagrams with internal quark loops. In addition, the $\eta'$ ``hairpin'' vertex leads to a new correction, proportional to $m_{q}^{1/2}$. We compare our results to numerical lattice data and use them to estimate the size of the quenching error in the octet baryon masses.Comment: 7 pages (An abridged version of this note will appear in the proceedings of Lattice'93. Latex + 14 postscript files, bundled using uufiles. Needs psfig.) UW/PT-93-0

Linking teaching and research in disciplines and departments

This paper supports the effective links between teaching and discipline-based research in disciplinary communities and in academic departments. It is authored by Alan Jenkins, Mick Healey and Roger Zetter

A Terrorism Analysis of the April 14, 2014, Bus Terminal Bombing in Abuja, Nigeria

This Transportation Security Perspective is the fourth in a continuing series produced by the National Transportation Safety and Security Center of the Mineta Transportation Institute. These examine major terrorist attacks and trends in terrorists targeting surface transportation. Previous perspectives include the terrorist bombings in Volgograd, Russia; the assault on passengers at the Kunming train station in China; and the reported plot against the Metro in Los Angeles

“Smashing Into Crowds” -- An Analysis of Vehicle Ramming Attacks

Vehicle ramming attacks are not new. But since 2010 Jihadists have urged their use. Is this the wave of the future, or a terrorist fad? To answer this and other questions the authors expanded and updated the database used in their May 2018 MTI Security Perspective entitled An Analysis of Vehicle Ramming as a Terrorist Threat to include 184 attacks since January 1, 1970. They also reviewed literature and examined some cases in detail. This MTI Security perspective indicates that while not new, vehicle rammings are more frequent and lethal since 2014, although the number of attacks seems to be dropping in 2019. Still it is too early to know if this is because of government countermeasures or because it is a fad that has come and gone. They also found that: (a) the majority of attacks occur in developed countries like the US and Europe; (b) though not more lethal than some other tactics they can be easily carried out by those who cannot get bombs or guns in a target-rich environment that is difficult to protect; (c) while Jihadists (responsible for only 19% of the attacks) have exhorted their use since 2010, it isn’t clear these calls have been successful -- instead the pattern of attacks suggest a kind of wider contagion; (d) attackers plowing vehicles into public gatherings and pedestrianized streets are the most lethal, particularly the attacks are planned and the drivers rent or steal large trucks or vans driven at speed; and finally, (e) government authorities cannot prevent these attacks but can and are doing things to prevent them and mitigate fatalities when they occur

By the Numbers: Russia’s Terrorists Increasingly Target Transportation

If body count is the terrorists’ goal, then surface transportation provides an attractive target— crowds of strangers in confined environments. While Umarov’s Chechen predecessors carried out spectacular hostage seizures at hospitals, a primary school, and even at a theater in the heart of Moscow, trains, subways, and buses have featured heavily among their targets

Development of high thermal conductivity polymeric materials for spacecraft use Final report, 1 Jul. 1966 - 31 May 1969

High thermal conductivity polymeric materials for spacecraft applications using phenyl compound