Scaling in the time-dependent failure of a fiber bundle with local load sharing

We study the scaling behaviors of a time-dependent fiber-bundle model with local load sharing. Upon approaching the complete failure of the bundle, the breaking rate of fibers diverges according to r(t)proportional to(T-f-t)(-xi) where T-f is the lifetime of the bundle and xi approximate to 1.0 is a universal scaling exponent. The average lifetime of the bundle [T-f] scales with the system size as N-delta, where delta depends on the distribution of individual fiber as well as the breakdown rule. [S1063-651X(99)13902-3].

Failure of fiber bundles with local load sharing

We develop a recursion-relation approach for calculating the failure probabilities of a fiber bundle with local load sharing. This recursion relation is exact, so it provides a way to test the validity of the various approximate methods. Applying the exact calculation to uniform and Weibull threshold distributions, we find that the most probable failure load coincides with the average strength as the size of the system N --> infinity.

BURST-SIZE DISTRIBUTION IN FIBER-BUNDLES WITH LOCAL LOAD-SHARING

A critical load x(c) is introduced into the fiber-bundle model with local load-sharing. The critical load is defined as the average load per fiber that causes the final complete failure. It is shown that x(c) --> 0 when the size of the system N --> infinity. A power law for the burst-size distribution, D(DELTA) is-proportional-to DELTA(-xi) is approximately correct. The exponent xi is not universal, since it depends on the strength distribution as well as the size of the system.

The After Slavery Website: A New Online Resource for Teaching U. S. Slave Emancipation

Historiographical essay and evaluation of textbooks and web-based resource for teaching slave emancipation. Published to coincide with re-launch of After Slavery website (www.afterslavery.com) in partnership with Lowcountry Digital Library, College of Charleston, SC.

Sharing Classes between Separate Schools: a mechanism for improving inter-group relations in Northern Ireland?

One manifestation of division and the history of conflict in Northern Ireland is the parallel education system that exists for Protestants and Catholics. Although recent decades have seen some advances in the promotion of integrated education, around 95% of children continue to attend schools separated on ethno-religious lines. In 2007 a programme for sharing education was established. Underpinned by intergroup contact theory, and reflecting educational priorities shared by all school sectors, the programme seeks to offer children from different denominational schools an opportunity to engage with each other on a sustained basis. In this article the authors adopt a quantitative approach to examining the impact of participation in the Sharing Education Programme on a range of outcomes (out-group attitudes, positive action tendencies and out-group trust) via, first, intergroup contact (cross-group friendships) and, second, intergroup anxiety. Their findings confirm the value of contact as a mechanism for promoting more harmonious relationships, and affirm the Sharing Education Programme as an initiative that can help promote social cohesion in a society that remains deeply divided.

How resource quality differentially affects motivation and ability to fight in hermit crabs

Contesting animals typically gather information about the resource value and that information affects fight motivation. However, it is possible that particular resource characteristics alter the ability to fight independently of the motivation. Using hermit crabs, we investigate how the resource in terms of shell quality affects both motivation and ability to fight. These crabs fight for shells, but those shells have to be carried and may impose physiological costs that impede fight vigour. We find that the shell has different effects on motivation and ability. Potential attackers in very small shells were highly motivated to attack but, rather than having enhanced ability, unexpectedly quickly fatigued and subsequently were not more successful in the fights than were crabs in larger shells. We also examined whether defending crabs could gather information about the attacker's shell from the vigour of the attack. Defending crabs gave up quickly when a potential gain had been assessed, indicating that such information had been gathered. However, there was no indication that this could be owing to the activity of the attacker and the information is probably gathered via visual assessment of the shell.

An Examination of Volunteer Motivation in Credit Unions: Informing Volunteer Resource Management

Volunteer recruitment and retention is a problem that most credit unions experience. Research suggests that knowledge of volunteer motivation can inform volunteer management strategies. This paper uses a survey approach to determine whether current volunteers in credit unions in Northern Ireland are more motivated by the actual act of volunteering, by the output from the volunteering activity (including altruism) or because the volunteering activity increases their human capital value. Altruistic reasons are found to be the most influential, with the act of volunteering also scoring highly. This knowledge should inform volunteer recruitment programmes and internal appraisal processes as management can reinforce messages that provide positive feedback to volunteers on the social benefits being achieved by the credit union. This will further motivate current volunteers, ensuring retention. When motivation was analyzed by volunteer characteristics we found that older volunteers, retired volunteers and volunteers who are less educated are more motivated in their role. There was little evidence that individuals volunteer to improve their human capital worth.

Managing SMT Resource Usage through Speculative Instruction Window Weighting

Simultaneous multithreading processors dynamically share processor resources between multiple threads. In general, shared SMT resources may be managed explicitly, for instance, by dynamically setting queue occupation bounds for each thread as in the DCRA and Hill-Climbing policies. Alternatively, resources may be managed implicitly; that is, resource usage is controlled by placing the desired instruction mix in the resources. In this case, the main resource management tool is the instruction fetch policy which must predict the behavior of each thread (branch mispredictions, long-latency loads, etc.) as it fetches instructions.

Clustered indexing for branch predictors

As a result of resource limitations, state in branch predictors is frequently shared between uncorrelated branches. This interference can significantly limit prediction accuracy. In current predictor designs, the branches sharing prediction information are determined by their branch addresses and thus branch groups are arbitrarily chosen during compilation. This feasibility study explores a more analytic and systematic approach to classify branches into clusters with similar behavioral characteristics. We present several ways to incorporate this cluster information as an additional information source in branch predictors.