Diffusion of muonium and hydrogen in diamond

Jump rates of muonium and hydrogen in diamond are calculated by quantum transition-state theory, based on the path-integral centroid formalism. This technique allows us to study the influence of vibrational mode quantization on the effective free-energy barriers Delta F for impurity diffusion, which are renormalized respect to the zero-temperature classical calculation. For the transition from a tetrahedral (T) site to a bond-center (BC) position, Delta F is larger for hydrogen than for muonium, and the opposite happens for the transition from BC to T. The calculated effective barriers decrease for rising temperature, except for the muonium transition from T to BC sites. Calculated jump rates are in good agreement to available muon spin rotation data.Comment: 4 pages, 3 figure

The Canterbury tales : a study of certain of the characters and their tales as an expression of Chaucer's concern regarding abuses among the priesthood and religious orders during the 14th century

Includes bibliographical references.When one considers The Canterbury Tales, which is generally accepted as being Chaucer's most important work, as a whole, one encounters two facts which immediately suggest an interest in the religious and ecclesiastical states and a deep concern resulting from the prevalence of abuses in the lives of these representatives of the Church. The first of these facts is Chaucer's use of the concept of a pilgrimage as framework for his tales. One cannot, of course, completely discount the suggestion that the poet's use of this framework could have been motivated by the fact that, in the fourteenth century at any rate, only a pilgrimage could have provided a socially acceptable dimension for keeping so diverse a group of people together for long enough to tell their tales. However, the fact that a pilgrimage was fundamentally a religious act was, I feel, a more important consideration to the poet in his choice of this particular framework for his tales. Baldwin, writing about the significance of pilgrimages in the middle ages says: "Pilgrimage was a well-established feature of European society, it was a journey of devotion to a holy shrine. At first simply a pious act, pilgrimage had, in the course of time, been adopted by the Church as a form of canonical penance." John Norton-Smith sees a probable connection between the poet's Retractation and his choice of a pilgrimage-framework when he says: "the biologically based metaphor of the pilgrimage of life and the final spiritual resignation of the author suggests a powerful tendency towards an acceptance of the orthodox 'other-worldly' religious view of human activity". A pilgrimage was, therefore, primarily a penitential activity designed to turn the mind and the heart to the love of God. Since the abuses of which the religious and clergy were accused were, for the most part, the result of a weakening of the life of penance and self denial and a turning away from divine love, the poet's choice of a pilgrimage as the framework for The Canterbury Tales might also be interpreted as the first indication Chaucer gives of his concern regarding the abuses he observed in the fourteenth-century Church. The second indication that Chaucer used The Canterbury Tales as a vehicle through which to express his concern regarding the religious and ecclesiastical abuses he observed, is the inclusion among his twenty nine pilgrims of no fewer than eleven who are directly or indirectly involved in the religious or clerical life and who represent every kind of ecclesiastic and religious with whom the faithful were likely to come in frequent contact. It is an indisputable fact that the clergy and religious still accounted for a large percentage of the population in the fourteenth century, but there does not appear to be any indication that this number is as high as would be expected if Chaucer's main aim in the assembling of his pilgrimage was to obtain a cross section of fourteenth-century society. In the General Prologue to The Canterbury Tales Chaucer sets the scene for what might be described as a systematic revelation of fourteenth-century religious and ecclesiastical abuse. In his seemingly innocuous and often amusing portrait, Chaucer had to find ways of achieving his aim without having recourse to conventional moralizing and without exposing himself to the social and occupational hazards which a direct attack on the clergy and religious might involve at this time. He achieved his aim by arranging his pilgrims in such a way that a description of each character was required and each was obliged to tell at least one tale. The poet further precluded any unpleasant consequences which could have resulted from his revelation of various types of abuse by inventing a narrator-a rotund, insignificant figure who, in the eyes of the Host and of the other pilgrims, could produce no better poetry than a few stanzas of doggerel verse

Playfulness and prenatal alcohol exposure : a comparative study

Includes abstract. Includes bibliographical references

An investigation into the relationship between student identity and academic literacy at a private higher education institution

Although academic development programmes have been well researched in the South African context, much of the research has focused on programmes at mainstream public universities and less is known about the programmes run by smaller private institutions. This research aims to identify and discuss themes around student identity and how these themes relate to academic literacy acquisition for students on a one-year bridging course programme at a private university. Gee’s (2001) identity framework is used to explore and compare how students on a bridging course were viewed by the institution, and how these students saw themselves. An analysis of data gathered through interviews, focus groups, questionnaires, and course-related materials revealed a strong deficit discourse around students on the bridging course. The institution’s view of literacy as autonomous, the deficit discourse surrounding the students, and the way these students were positioned in the institution, meant that students, although highly motivated to achieve a degree qualification, had not begun to develop the beginning of either an academic or a vocational identity. The institution did not successfully enable students to view academic practice and discourse as part of their identity, and as a result bridging course students did not adopt the practices and discourses around academic literacy as they were not convinced of their validity and legitimacy. Given that academic literacy is central to success on a degree programme, these students were not adequately prepared for their first year of degree study. The findings from this research show the need for wider research into whether academic development programmes at private institutions are really meeting the needs of the students who enrol onto these programmes

Evaluating the viability of pumpable emulsion explosives for use in narrow reef mining operations

Pumpable emulsion explosives have been available to surface and underground massive mining operations for decades and through their unique properties offer significant advantages through improved safety, reliability and performance. Despite their advantageous properties the benefits of pumpable emulsions have been unavailable to narrow reef mining operations due to the void in technology necessary for their successful implementation within the challenging environment. The purpose of the following research report is to evaluate the viability of pumpable emulsion explosives for use in South African narrow reef mining operations. By approaching the problem from multiple perspectives, this research report aimed first to propose a theoretical framework and suite of equipment suitable for the implementation of pumpable emulsions within the narrow reef environment. Through the development of this equipment, controlled tests could be undertaken on the proposed narrow reef emulsion formulations and pumpable emulsion technology to obtain the necessary understanding of the performance of the system under controlled conditions. Once an understanding had been obtained for the controlled performance of the system, a field study could be undertaken in order to compare the performance of the new pumpable emulsion system with available explosives within the underground mining industry. Through the results obtained a comparison could be made of the blasting efficiency and feasibility of pumpable emulsions when compared to existing explosives within the narrow reef environment. Given the vast difference in underground narrow reef and massive mining operations, fundamental changes were necessary with regard to emulsion technology prior to the successful implementation of the narrow reef emulsion system. Following the development of the system, controlled explosives tests allowed for optimisation of the pump technology as well as recommended daily practices. Blast results achieved in field trials with the narrow reef emulsion system allowed for improved blasting efficiency while reducing explosives costs per tonne broken. While blast results and efficiencies improved throughout pumpable emulsion trials, variances in daily blasting practices including the use of stemming, overcharging and varying priming practices influenced the results obtained. Further testing is therefore recommended in order to determine the influence of variables on the results obtained such that a specific increase in blasting efficiency can be determined

Different origin of the ferromagnetic order in (Ga,Mn)As and (Ga,Mn)N

The mechanism for the ferromagnetic order of (Ga,Mn)As and (Ga,Mn)N is extensively studied over a vast range of Mn concentrations. We calculate the electronic structures of these materials using density functional theory in both the local spin density approximation and the LDA+U scheme, that we have now implemented in the code SIESTA. For (Ga,Mn)As, the LDA+U approach leads to a hole mediated picture of the ferromagnetism, with an exchange constant $N\beta$ =~ -2.8 eV. This is smaller than that obtained with LSDA, which overestimates the exchange coupling between Mn ions and the As $p$ holes. In contrast, the ferromagnetism in wurtzite (Ga,Mn)N is caused by the double-exchange mechanism, since a hole of strong $d$ character is found at the Fermi level in both the LSDA and the LDA+U approaches. In this case the coupling between the Mn ions decays rapidly with the Mn-Mn separation. This suggests a two phases picture of the ferromagnetic order in (Ga,Mn)N, with a robust ferromagnetic phase at large Mn concentration coexisting with a diluted weak ferromagnetic phase.Comment: 12 pages, 11 figure

Ion Channeling Analysis of Gallium Nitride Implanted with Deuterium

Ion channeling and transmission electron microscopy were used to examine the microstructure of GaN implanted with deuterium (D) at high (>1 at. %) and low (< 0.1 at. %) D concentrations. At high concentrations, bubbles and basal-plane stacking faults were observed. Ion channeling showed the D was disordered relative to the GaN lattice, consistent with precipitation of D2 into bubbles. At low D concentrations, bubbles and stacking faults are absent and ion channeling shows that a large fraction of the D occupies sites near the center of the c-axis channel

An assessment of the water use of indigenous and introduced tree SPP. and varying land uses around Vasi Pan, Maputaland, KwaZulu-Natal.

Master of Science in Hydrology. University of KwaZulu-Natal, Pietermaritzburg, 2017.Abstract available in PDF file