On selection criteria for problems with moving inhomogeneities

We study mechanical problems with multiple solutions and introduce a thermodynamic framework to formulate two different selection criteria in terms of macroscopic energy productions and fluxes. Studying simple examples for lattice motion we then compare the implications for both resting and moving inhomogeneities.Comment: revised version contains new introduction, numerical simulations of Riemann problems, and a more detailed discussion of the causality principle; 18 pages, several figure

Late Budgets

The budget forms the legal basis of government spending. If a budget is not in place at the beginning of the fiscal year, planning as well as current spending are jeopardized and government shutdown may result. This paper develops a continuous-time war-of-attrition model of budgeting in a presidential style-democracy to explain the duration of budget negotiations. We build our model around budget baselines as reference points for loss averse negotiators. We derive three testable hypotheses: there are more late budgets, and they are more late, when fiscal circumstances change; when such changes are negative rather than positive; and when there is divided government. We test the hypotheses of the model using a unique data set of late budgets for US state governments, based on dates of budget approval collected from news reports and a survey of state budget o¢ cers for the period 1988-2007. For this period, we find 23 % of budgets to be late. The results provide strong support for the hypotheses of the model.government budgeting; state government; presidential democracies; political economy; late budgets; fiscal stalemate; war of attrition

Colorectal carcinoma-a New threat to black patients? A retrospective analysis of colorectal carcinoma received by the Institute for Pathology,University of Pretoria

Objective. To compare black and white patients with colorectal carcinoma treated at Pretoria Academic and Kalafong hospitals, and to compare pathological trends of our study population with others reported in the literature.Design. A retrospective study of all cases of resected colorectal carcinomas received by our department during the periods 1986 - 1987 (82 cases) and 1996- 1997 (91 cases). To investigate variables of age, race and gender distribution in the two study populations.Methods. Routinely stained histological sections of all relevant cases were examined. Findings regarding age, gender, population group, anatomical location of the tumour and presence of other pathological lesion were recorded. Changes in the referral population and number of surgical specimens received were also considered during statistical analysis of the study finding .Results. There has been a significant increase in the number of black patients with colorectal carcinoma at our Institute. In addition, adenomatous polyps were found in 9 of our black patients (1996/97). This is significantly higher than expected from reports in the literature. This could be predictive of an increase in incidence of colorectal carcinomas in our black population. Black patients were also found to be considerably younger at age of presentation than their white counterparts . A further" significant finding was a considerable increase in the number of black female under the age of 40 years from 1986/ 87 to 1996/ 97. On the other hand, the number of white females above 40 years of age decreased considerably over this time. The reason for this finding is uncertain and warrants further study

Closing the Gap? Persistent Underperformance of Black Minorities in Former Whites-Only SA Schools

This paper is based on a study that explored the life experiences of Xhosa-speaking learners as a minority in a former whites-only school in the Western Cape province of South Africa. The focus was specifically on the factors that contribute to the continued poor academic performance of this minority group within the school. Identifying and understanding these factors as challenges to academic success can help teachers and schools provide appropriate support structures to maximize the potential of these learners. Research has shown that programs of support will only be effective if they appreciate and cater to the needs of the learners concerned (Michael, Andrade & Bartlett, 2007; Ogbu 2003; Rhamie & Hallam, 2002). The purpose of this paper is to highlight the role of peers and teachers in contributing to persistent underperformance of minority Xhosa speakers in a former whites-only school in the Western Cape province of South Africa

Using log diaries to examine the activities of final-year medical students at decentralised training platforms of four South African universities

Background. An important strategy in the transformation and scaling up of medical education is the inclusion and utilisation of decentralised training platforms (DTPs). Objective. In light of the dearth of research on the activities of medical students at DTPs, the purpose of this study was to determine how final-year medical students spent their time during the integrated primary care (IPC) rotation at a DTP. Methods. The study was conducted at Sefako Makgatho Health Sciences University (SMU), the University of KwaZulu-Natal (UKZN), the University of the Witwatersrand (Wits) and Walter Sisulu University (WSU). At each of the participating universities, a voluntary group of final-year medical students completed a log diary by entering all activities for a period of 1 week during the IPC rotation. The log diary contained five activity codes: clinical time teaching time, skill time, community time and free time, with each subdivided into additional categories. The data were analysed for students at each university separately, using frequencies and proportions. Results. A total of 60 students volunteered to complete the diaries: at WSU n=21; UKZN n=11; Wits n=18; and SMU n=10. At each university, students reported that they spent large amounts of time on clinical activities: WSU=46.0%; UKZN=33.8%; Wits=29.6%; and SMU=44.1%. They reported low amounts of time spent on community-based activities: WSU 0.8%; UKZN 7.6%; Wits 6.8%; and SMU 0.0%. Conclusion. Students reported that they spent a sizeable proportion of their time on clinical activities, while reported time spent on community-based activities was negligible. The transformation potential of DTPs will only be realised when students spend more time on community-based activities

Effect of root fracture on the epithelial attachment

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