Optimization of deliveries from distribution points

We solve an optimization problem involving the assignment of transport routes to a delivery point. The general and particular cases of the optimization problem are described. An algorithm for the simplified case and ideas for the general case is presented

The vortex state in the BEC to BCS crossover: a path-integral description

We derive a path-integral description of the vortex state of a fermionic superfluid in the crossover region between the molecular condensate (BEC) regime and the Cooper pairing (BCS) regime. This path-integral formalism, supplemented by a suitable choice for the saddle point value of the pairing field in the presence of a vortex, offers a unified description that encompasses both the BEC and BCS limits. The vortex core size is studied as a function of the tunable interaction strength between the fermionic atoms. We find that in the BEC regime, the core size is determined by the molecular healing length, whereas in the BCS regime, the core size is proportional only to the Fermi wave length. The observation of such quantized vortices in dilute Fermi gases would provide an unambiguous proof of the realization of superfluidity in these gases.Comment: 10 pages, 2 figure

Application of Monte Carlo-based statistical significance determinations to the Beta Cephei stars V400 Car, V401 Car, V403 Car and V405 Car

We have used Lomb-Scargle periodogram analysis and Monte Carlo significance tests to detect periodicities above the 3-sigma level in the Beta Cephei stars V400 Car, V401 Car, V403 Car and V405 Car. These methods produce six previously unreported periodicities in the expected frequency range of excited pulsations: one in V400 Car, three in V401 Car, one in V403 Car and one in V405 Car. One of these six frequencies is significant above the 4-sigma level. We provide statistical significances for all of the periodicities found in these four stars.Comment: 11 pages, 17 figure

A retrospective cohort study: The retention in care of HIV positive pregnant and breastfeeding patients universally initiated on lifelong ART ('OptionB+') in the Klipfontein/Mitchells Plain substructure in Cape Town

The implementation of 'Option B+' has increased uptake and access to antiretroviral (ART) care. However, growing concerns exist regarding retention, especially once vertical transmission risk ceases. Considering the importance of adherence to achieve virological suppression and avoid resistance research on retention is crucial. This study compares the retention of women initiated on 'Option B+' to that of women initiating ART for their own health. Additionally possible predictors of loss to follow-up (LTFU) were explored. Women initiating ART between 1 April and 31 August 2013 were allocated to either the pregnant (n=228) or non-pregnant (n=177) cohort. Retrospective review of electronic recordkeeping systems and patient folders measured retention up to 15 months after ART initiation. Demographic data was captured to explore predictors of LTFU. To avoid outcome bias with participants transferred out, analysis included a 'worst case' scenario assuming LTFU of all these participants and a 'best case' scenario assuming continued retention in care

Factors associated with emotional exhaustion in undergraduate and postgraduate nursing students

Background. Nursing students face dual stress from a combination of academic and clinical demands, which may affect their emotional wellbeing. Poor emotional wellbeing may prevent them from gaining the necessary knowledge and skills to care for patients. Objectives. To describe and compare levels of emotional exhaustion, personal accomplishment, compassion satisfaction, compassion fatigue and perceived stress of undergraduate and postgraduate nursing students, and to determine the influence of compassion fatigue, perceived stress and disengaged coping on emotional exhaustion. Methods. This study was a cross-sectional descriptive survey at a purposively selected South African university. There were 685 students, of whom 471 (68.8%) completed the questionnaire, which comprised a biographical section, as well as standardised and validated scales. Results. The respondents obtained a moderate score for perceived stress and were at average risk for emotional exhaustion and compassion fatigue. There were statistically significant differences between undergraduates and postgraduates on all scales, with undergraduates faring the worst. Stress from assignments and workload, lack of professional knowledge and skills, teachers and nursing staff and compassion fatigue made a statistically significant contribution to the prediction of emotional exhaustion in undergraduates. Compassion fatigue and stress from assignments and workload made a statistically significant contribution to the prediction of emotional exhaustion in postgraduates. Conclusion. Nursing students had moderate stress scores and were at average risk for emotional exhaustion and compassion fatigue, with undergraduate students faring the worst. Schools of nursing should prioritise the emotional wellbeing of their students, particularly that of undergraduates

Differential Interferometry Techniques on L-Band Data Employed for the Monitoring of Surface Subsidence Due to Mining

Mining activities in South Africa changes the natural environment in several ways. Challenges for mining companies lie in the detection and monitoring of surface subsidence and there exists a need for a long term monitoring system. Field-based techniques for deformation measurement are labour intensive and time consuming and, consequently, the implementation of these techniques for long-term monitoring is not ideal. On the other hand, satellite remote sensing data provides a synoptic view of an area and the repeat image acquisition strategy implies that the long-term monitoring of surface deformation is a possibility. This paper investigates the use of L-band ALOS PALSAR data for the detection and monitoring of surface subsidence due to underground mining activities in the Witbank Coalfields. Surface subsidence was detected for a period of over 3 years between 2007/08/16 and 2010/10/09. Centimetre scale surface deformation was detected in the study area and is associated with areas of active mining. The systematic evolution of the surface deformation basins over time was recognised and is consistent with the advance of the working face of the mine during the same period. The results confirm that L-band synthetic aperture radar data through dInSAR techniques can be used for the long-term monitoring of surface subsidence associated with mining activities

BCS-to-BEC crossover from the exact BCS solution

The BCS-to-BEC crossover, as well as the nature of Cooper pairs, in a superconducting and Fermi superfluid medium is studied from the exact ground state wavefunction of the reduced BCS Hamiltonian. As the strength of the interaction increases, the ground state continuously evolves from a mixed-system of quasifree fermions and pair resonances (BCS), to pair resonances and quasibound molecules (pseudogap), and finally to a system of quasibound molecules (BEC). A single unified scenario arises where the Cooper-pair wavefunction has a unique functional form. Several exact analytic expressions, such as the binding energy and condensate fraction, are derived. We compare our results with recent experiments in ultracold atomic Fermi gases.Comment: 5 pages, 4 figures. Revised version with one figure adde

Assessing and serving families and communities responsibly: challenges posed in an urban, marginalised setting

Service provision to families and communities has long been recognised as a complex undertaking involving a multiplicity of role players and systems of care. Systems theory and ecological theory provide useful frameworks for understanding and servicing families and communities, yet there is a clear absence of literature and research on how to converge microsystemic with macrosystemic interventions. Using Rojano\'s1 community family therapy model, which is applicable to South American communities, and Kasiram and Oliphant\'s2 strategies for changing traditional family therapy to suit broader contexts in South Africa, the authors used developmental research within a qualitative framework to develop an indigenous community family therapy model in an urban setting in KwaZulu-Natal, South Africa. The authors utilised nursing students as fieldworkers and service providers in this study. The research process involved several steps: a state-of-the-art review of the family and community, achieved through an assessment of the family and community through community profiling and an epidemiological study of the community; family assessment of families with one child under the age of five years; best practice and model development to intervene at the family and community levels, achieved with the help of community and school meetings and workshops to identify and prioritise needs and problems, followed by bio-psychosocial interventions; refining the model achieved by an evaluation of the interventions through report assessment and on-site assessment and recommending model adjustments based on the evaluation. In designing a community family therapy model, the state-of-the-art review of community needs established several core issues requiring services/interventions. These were problems relating to HIV/AIDS; a lack of knowledge of the immunisation programme in South Africa and of the Road to Health chart; teenage pregnancy and its relationship to risky behaviours, HIV/AIDS, poverty and crime; and a lack of communication within the family. The development of the model involved determining interventions with families and the community, using macrosystemic approaches, such as community meetings and workshops, where priorities were established and joint strategies were planned to address the identified problems. Individual and small-group discussions enriched the understanding of problems/needs, which, combined with macrosystemic approaches such as media coverage and community meetings and workshop/events, worked in synchrony to effectively assess and then service the families and communities. The goal of developing a community family therapy model was achieved. Combining microsystemic and macrosystemic approaches to assess and serve families and communities is particularly helpful in the face of apathy. However, once momentum is achieved in securing a community spirit, it needs to be sustained or else it is lost and may require more effort to reclaim in the future. Thus, if services are provided by educational institutions, it would be in the best interests of both future students and the community if there is funding to support service outside of the academic year..South African Family Practice Vol. 49 (9) 2007: pp. 4-