530 research outputs found
A hydrodynamical homotopy co-momentum map and a multisymplectic interpretation of higher order linking numbers
In this article a homotopy co-momentum map (\`a la
Callies-Fr\'egier-Rogers-Zambon) trangressing to the standard hydrodynamical
co-momentum map of Arnol'd, Marsden and Weinstein and others is constructed and
then generalized to a special class of Riemannian manifolds. Also, a covariant
phase space interpretation of the coadjoint orbits associated to the Euler
evolution for perfect fluids and in particular of Brylinski's manifold of
smooth oriented knots is discussed. As an application of the above homotopy
co-momentum map, a reinterpretation of the (Massey) higher order linking
numbers in terms of conserved quantities within the multisymplectic framework
is provided and knot theoretic analogues of first integrals in involution are
determined.Comment: 21 pages, 3 figures. The present version focuses on the connections
between multisymplectic geometry, hydrodynamics and vortices. The derivation
of the HOMFLYPT polynomial via geometric quantization has been proposed as a
separate preprint, see "Derivation of the HOMFLYPT knot polynomial via
helicity and geometric quantization ", arXiv:1910.xxx
Measurement of temperature change in paediatric patients undergoing MRI examinations under general anaesthesia
A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Masters of Medicine in Anaesthesia Johannesburg, 2014Background and objectives of study: Paediatric patients undergoing Magnetic Resonance Imaging (MRI) procedures are at risk of hypo- or hyperthermia. This study was aimed at determining if there is a change in core temperature in paediatric patients undergoing MRI examinations under general anaesthesia. The objectives included describing the change in temperature during MRI scans, and correlating temperature change with age, weight and MRI scan duration.
Method: This study followed a prospective, contextual and descriptive research design. The study population was paediatric patients who presented for MRI scans under general anaesthesia at Chris Hani Baragwanath Academic Hospital. A convenience, consecutive sampling method was employed and 29 patients aged 6 months to 5 years whose baseline temperatures were below 37.5℃ participated in the study.
Tympanic temperature was measured using an infrared thermometer before induction of general anaesthesia. Inhalational general anaesthesia was induced with incremental concentrations Sevoflurane in a mixture of Nitrous oxide and Oxygen (70:30 %) using an MRI compatible anaesthesia machine. General anaesthesia was maintained with spontaneous inhalation of Sevoflurane in a mixture of O₂ and Air (60:40 %) via a laryngeal mask airway. Tympanic temperature was measured again on completion of the MRI scan within 2 minutes of emergence from general anaesthesia. The change between pre and post scan temperatures was tested for significance using the paired t-test. Correlations were made using the Pearson correlation coefficient.
Results: The mean age of the participants was 31 months and the median 24 months. The mean weight was 13.2 kg, the median 12 kg, and the range 5 to 29 kg. The mean MRI scan duration was 51 minutes, the median 50 minutes and range 30 minutes to 80 minutes. All participants experienced some loss of temperature (0.1 – 2.3 ℃). The mean temperature loss was 0.93℃ and was statistically significant (p=0.001). The 95% confidence interval for temperature change was 0.70 – 1.15 ℃. No statistically significant correlations were found between temperature loss and age (r=-0.028), weight (r=-0.042) and scan duration (r=-0.041).
Conclusion: Heat loss in the harsh MRI environment is an underestimated problem. In addition, the ferromagnetic environment precludes continuous temperature monitoring. This study has shown that temperature does drop in paediatric patients undergoing MRI examinations under general anaesthesia. This change in temperature did not correlate with age, weight, and duration of the MRI scan
Internationalization and survival of foreign subsidiaries of emerging economy multinationals
Master'sMASTER OF SCIENCE (MANAGEMENT
Analysing ICT Investment by Micro-enterprises in the Western Cape
Magister Commercii (Information Management) - MCom(IM)Micro-enterprises solve many socio-economic issues facing developing nations because of their large contribution to economic development and progress. Micro-enterprises have been influenced by the continued globalisation, digitisation and modernisation of business practices. As a result, micro-enterprises’ are investing in Information and Communication Technologies (ICT) to enhance enterprise and economic growth, performance, productivity and a competitive advantage. However, the benefits of these investments are not always realised, often because of the ad hoc nature in which micro-enterprises function and a lack of formalised methods and strategy. When these are not realised, micro-enterprise suffer in terms of competitiveness, performance and returns.
Maturity models, are tools that help solve issues relating to an enterprise’s current status in terms of its capabilities and resources, and how these issues can be improved. Maturity models may present the ideal solution for micro-enterprise to invest in ICT. Larger enterprises have been able to use maturity models for strategic ICT investments realising benefits. The benefits of using maturity models as a guide to ICT investment include: saving on long-term operational and tactical costs, self-evaluation and linking business and ICT strategy among others.
This research sought to determine how micro-enterprises in the Western Cape can use a maturity model in planning strategy for investments in ICT. Data was gathered from micro-enterprises and their stakeholders to find the best maturity model fit. These model fitness considered the entire internal and external environmental factors influencing micro-enterprise ICT investment decision-making.
The research investigated micro-enterprises, their current practices, focus and strategic, tactical and operational behaviour in terms of business and ICT. Of the 34 micro-enterprises that took part, most them knew of the concept of growth and maturity of the enterprise, they used none discernable metric to measure their internal and external activities regarding ICT investment. It highlighted the alignment of business and ICT as a major issue that needed to be addressed in order for micro-enterprises to be competitive, improve performance and returns. The recommended model from the research provides a formalised process that covers both the micro-enterprises internal and external matrices when deciding on the ICT investment to be made
DIMENSI SYARIAH COMPLIANCE PADA OPERASIONAL BANK SYARIAH
Label Bank Syariah is not only a name, the consequences of the name impact on all aspects of its operations. Sharia Bank Operations must / must comply with the principles of sharia (Sharia Compliance). Broadly speaking there are seven dimensions of shariah compliance in the operations of Islamic Banks as follows: 1) does not contain elements of usury, 2) avoid bai 'al-inah, 3) does not contain gharar, 4) does not contain maisir, 5) Business run based on (7) Managing zakat, infaq and shadaqah in accordance with syaria
Mathematical models for cellular aggregation: the chemotactic instability and clustering formation
In this thesis we present a mathematical formulation of the interaction between microorganisms such as bacteria or amoebae and chemicals, often produced by the organisms themselves. This interaction is called chemotaxis and leads to cellular aggregation. We derive some models to describe chemotaxis. The first is the pioneristic Keller-Segel parabolic-parabolic model and it is derived by two different frameworks: a macroscopic perspective and a microscopic perspective, in which we start with a stochastic differential equation and we perform a mean-field approximation. This parabolic model may be generalized by the introduction of a degenerate diffusion parameter, which depends on the density itself via a power law. Then we derive a model for chemotaxis based on Cattaneo's law of heat propagation with finite speed, which is a hyperbolic model. The last model proposed here is a hydrodynamic model, which takes into account the inertia of the system by a friction force. In the limit of strong friction, the model reduces to the parabolic model, whereas in the limit of weak friction, we recover a hyperbolic model. Finally, we analyze the instability condition, which is the condition that leads to aggregation, and we describe the different kinds of aggregates we may obtain: the parabolic models lead to clusters or peaks whereas the hyperbolic models lead to the formation of network patterns or filaments. Moreover, we discuss the analogy between bacterial colonies and self gravitating systems by comparing the chemotactic collapse and the gravitational collapse (Jeans instability)
Musyarakah mutanaqishah Pada Perbankan Syariah di Indonesia: Pendekatan Maqasid Syariah
This study aims to identify the implementation of the musyarakah mutanaqishah contract in Islamic banking in Indonesia based on the Islamic maqasid review. This research uses descriptive qualitative method. The research data were collected using the documentation method. The data used in this research is secondary data obtained from various sources regarding the provisions of sharia fatwas, sharia standards, statutory regulations, operational and practical standards in Islamic banking, as well as the results of relevant research and publications. The data were analyzed using the inductive method. The analysis of the implementation of the musyarakah mutanaqishah contract is carried out based on the maqasid sharia approach. The results of the study found that the implementation of the musyarakah mutanaqishah contract as an alternative to mudharabah financing in Islamic banking, from the aspect of risk charging and equal partnerships, was not in accordance with the maqashid sharia and existing regulations in Indonesi
An evaluation of a psychosocial intervention for orphans on HIV treatment: A phase II RCT of memory work therapy at PASADA, Tanzania
Includes bibliographical referencesAim: Evidence shows high burden of psychosocial problems among orphaned children with HIV. Intervention studies have generally been conducted in developed countries. This mixed methods study aimed to determine whether Memory Work (MWT) Therapy 1 week group intervention improves outcomes for this complex population, in terms of their self-esteem, coping and psychological wellbeing compared to standard care, and to establish mechanisms of action. Method/Issue: An RCT Phase II of 48 Adolescents aged 14-18, full-orphaned AIDS on ART in Tanzania, with a waitlist control. Following (T0) baseline interviews, random allocation was for either intervention experimental condition (EC), or Control Condition (CC). All participated in second round of data collection (T1) at two weeks, and a final (T2) a month later. The EC children and caregivers participated in a focus group at T2. The CC then received the intervention 4 months later. Four questionnaires used, Brief Symptom Inventory (BSI), Rosenberg Self Esteem Scale (SES), Strengths and Difficulties Questionnaire (SDQ), and Self Efficacy Questionnaire (SEQ). Groups were compared at each time-point using multivariable linear regression controlling for baseline characteristics and group as independent variable, with change score as dependent variable. Qualitative data were subjected to thematic analysis to describe the experience of the intervention and how to refine it. Results/Comments: Significant differences favoured the EC at T1: BSI P<0.001, B=44.985, CI=25.5, 64.4), SDQ P=0.010, B=4.811, % CI 1.226, 8.396), SEQ both social scale P=0.015, B=-4.539, % CI-8.161,-0.918) and emotional scale P=0.002, B=-5.803 % CI-9.434, 2.171) (no effect for SES). At T2 we found these effects persisted: BSI P=0.001, B=46.668 %CI=21.541, 71.835), SDQ P=0.002, B=5.218 % CI 1.960, 8.476), SEQ both social scale P=<0.001, B=-7.791, % CI-11.320,-4.262) and emotional scale (P=<0.001, B=-9.007, % CI-12.032,-5.983). Additionally, at T2 found an EC effect for SES P<0.001, B=-4.392, %CI=-6.738,-2.046). The children recalled and described enjoying specific tasks within the intervention memory book, (such as "hero book" and the "tree of life") and described becoming "resilient" people. Discussion: The trial demonstrates improved outcomes in all measures for a complex population, i.e., bereaved children on treatment. Importantly, the effect did not attenuate and indeed self-esteem improved over time. The intervention should now be replicated in a fully powered trial
Creep and creep rupture of strongly reinforced metallic composites
A creep and creep damage theory is presented for metallic composites with strong fibers. Application is to reinforced structures in which the fiber orientation may vary throughout but a distinct fiber direction can be identified locally (local transverse isotropy). The creep deformation model follows earlier work and is based on a flow potential function that depends on invariants reflecting stress and the material symmetry. As the focus is on the interaction of creep and damage, primary creep is ignored. The creep rupture model is an extension of continuum damage mechanics and includes an isochronous damage function that depends on invariants specifying the local maximum transverse tension and the maximum longitudinal shear stress. It is posited that at high temperature and low stress, appropriate to engineering practice, these stress components damage the fiber/matrix interface through diffusion controlled void growth, eventually causing creep rupture. Experiments are outlined for characterizing a composite through creep rupture tests under transverse tension and longitudinal shear. Application is made to a thin-walled pressure vessel with reinforcing fibers at an arbitrary helical angle. The results illustrate the usefulness of the model as a means of achieving optimal designs of composite structures where creep and creep rupture are life limiting
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