First Fifty Theses

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Approaches to educational planning in underdeveloped countries

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1968
Document type: 
Thesis
File(s): 
Senior supervisor: 
K. Okuda
Department: 
Arts and Social Sciences: Economics and Commerce
Thesis type: 
Thesis (M.A.)

Hydrostatic pressure in relation to the synchronous culture of algae in open and closed systems.

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1968
Abstract: 

Chlorella ellipsoidea cultured using conventional methods under a 14: 10 light-dark regime in Bai j eririck ' s medium at 25?+ 1?with 700 ft-c illumination resulted in synchronous division with an n number of 4. Under identical conditions of light intensity, temperature, culture medium, and light-dark regime but in a closed system which was designs to study the effects of hydrostatic pressure on synchronous algae cultures, synchronous cell division did not occur and the n number was 2 or less at 1 atm. The most significant difference in the culture conditions arises because the concentrations of dissolved gases (mainly CCu and O^) remain relatively constant throughout the growth cycle in the open system while the gases vary in concentration continuously during the cycle in the closed system. In the closed system C>2 increases continuously c?CO-p decreases during the light period; the reverse is true in the dark. Analyses of the rati.os of dry weight, protein content, and cell size showed increases of approximately 2 in the closed system and 4 in the open system. The intent of this study was to determine effects of hydrostatic pressure on the physiology and morphology of algae. Therefore it was essential to develop techniques for successful culture in a closed system. Various modifications of culture conditions were made in attempts (only partially successful) to obtain equal growth in the two systems. 11 The effects of variations in some environmental parameters on the n number, dry weight, protein concentration, and cell size in the open and closed systems were investigated. With varied growing conditions of light intensity (15-700 ft--c), light- dark regimes (14: 10, 16: 8, 18: 6, 6: 18, 8: 16, 10: 14), media (Beijerinck, Burr, Sorokin, Tamiya and Morimura, and Beijerinck's modified with bicarbonate), CC^ concentration (0-100% saturation), and the addition of organic substances (glycolate, ascorbate, dithiothreitol) the n number and the ratios of increase in the other growth criteria were 4 in the open system but never more than 2 in the closed system. The n number and ratios of increase in dry weight, protein content and cell size were 4 in the open system at atmospheric Cu concentration but only 2 or less at high 02 (50 and 95%) concentration. These results indicate that high C>2 is probably responsible for the descrepancies in the n number and the rEitios of increase of the other criteria between the open and closed systems. Photosynthetically evolved 0^ in the closed system during the light period appears to be sufficient to induce this Warburg Effect. It was hypothesized that the Warburg Effect is responsible for the observed differences in increases in the growth criteria in the open and closed systems. Experiments were carried out to determine if photosynthetically evolved 02 was inhibiting cell growth. Using the Biological Oxygen Monitor algal samples were exposed to ? concentrations varying from 0 to 100% saturation at 25?with 700 ft-c Ill illumination. On the basis of these results which have indicated a decrease in the relative rates of O^ evolution at high 02 concentrations, it was concluded that Op evolved in the closed system could be responsible for the inhibition of photosynthesis. Synchronous growth under pressure has not yet been obtained. However, pressure effects on cell division were investigated. The n number was 4 in cells dividing while exposed to pressures of up to 200 atm, but pressures above 335 atm completely inhibited cell division. A possible mutagenic effect of pressure exposure on algal cells was considered.

Document type: 
Thesis
File(s): 
Senior supervisor: 
William Vidaver
Department: 
Science: Department of Biological Sciences
Thesis type: 
(Dissertation) Ph.D.

Luminescence studies in cadmium sulphide.

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1968
Abstract: 

This thesis describes some properties of the luminescence from single crystals and evaporated thin films of CdS under optical and electron beam excitation. A comparison . of optical and electron beam excitation mechan-ismSj as applied to the study of luminescence from solids,, is made. It is concluded that the variable penetration depth of high energy electrons with accelerating voltage can be readily used to distinguish between surface and bulk effects,, and that electron beam excitation can be used to advantage when the efficiency of a radiative process is low and high excitation intensity is required. The main advantage of optical excitation is in the vertical excitation of electrons from lower to higher energy levels which arises from the negligible momentum of the incident photons. Optical excitation spectra of various bound exciton emission lines in single crystals of Cds are , presented . It is shown that -the complex responsible for the so-called I, emission ^ due to the annihilation of an exciton bound to a neutral acceptor,, is created by the direct formation of bound excitons on the impurity site and by the formation of free or intrinsic excitons which are subsequently trapped on the impurity. The complexes responsible for the so-called 1 and I,- emission are also created by the formation of intrinsic excitons but more importantly they are created by direct phonon assisted formation of excitons bound to neutral and ionized impurities. It is concluded that the impurity involved is a donor. Electron beam excited luminescence from evaporated thin films of CdS is obtained. The transitions giving rise to this luminescence are identified as resulting from the recombination of free electrons with bound holes (free-bound emission) and from the recombination of bound electrons with bound holes (bound-bound emission) with the simultaneous emission of n LO phonons (n = 0,, 1, 2, ...). It is shown that if the films are coated with a 2000A thick layer of SiO , causing the CdS energy bands to be bent down at the X SiO - CdS interface,, the peak position of the free-bound emission x is shifted toward higher energies when the incident electrons have a small penetration depth (low energy). This is shown to result from an accumulation layer of electrons at the SiO - CdS inter- X. face .

Document type: 
Thesis
File(s): 
Senior supervisor: 
R.R. Haering
Department: 
Science: Department of Physics
Thesis type: 
(Dissertation) Ph.D.

Laser induced dielectric breakdown and mechanical damage in silicate glasses.

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1968
Abstract: 

Dielectric breakdown and mechanical damage in silicate glasses under high intensity laser radiation is investigated in detail. A Q-switched ruby laser is used to induce photoconductivity in soda glass., fused quartz and quartz crystal. 27 The number of charge carriers produced per laser pulse of 10 -2 -1 photons cm s is accounted for by multiphoton ionization of nonbridging oxygens in the silicon oxygen network. The relative magnitude of the effect proves that the photoconductivity does not result from ionization of sodium in glass as extensively quoted in literature. The lifetime of the charge carriers produced is estimated to be 10 s. Prom thermoelastic considerations a criterion for the validity of possible damage mechanisms is established. It is shown that stimulated Brillouin scattering cannot give rise to an effective absorption of 50 cm in the focal volume as required by the thermoelastic considerations. It is proposed and established that the mechanical damage is caused by the acceleration of primary electrons produced by multiphoton ionization, leading to a fully developed electronic instability in few nanoseconds. At this electron density the absorption in the focal volume is 10 cm" , and is responsible for the complete absorption of the laser pulse at intensities above the threshold for breakdown. The diffusion and recombination of electrons are found to be negligible, the only rate limiting - iii - process being the loss of electron energy to the lattice. The variation in the threshold intensity for breakdown in different glasses is due to the variations in the elastic scattering cross section. The study of the mechanical damage caused by a laser pulse., leads to the estimation of the surface energy of the (-material, which in the case of soda glass is found to be 10 ergs/cm The enhancement of the photoconductivity signal is obtained when -5 -4 a second laser pulse comes within the time 10 -5 x 10 sec. of the first pulse. The additional number of electrons produced by the second pulse is accounted for by the ionization of the color centers,, caused by trapping the electrons produced by the first pulse. - iv -

Document type: 
Thesis
File(s): 
Senior supervisor: 
K.E. Rieckhoff
Department: 
Science: Department of Physics
Thesis type: 
(Dissertation) Ph.D.

Uptake and evolution of carbon dioxide during photosynthesis : a survey of plant divisions.

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1968
Abstract: 

The exchange of CO2 in light was studied in plants of six divisions. The rates of CO2 uptake in light, of CO2 evolution in darkness, and the concentration of CO2 at C02 compensation point were measured in a closed system with an infrared gas analyser. The CO2 evolution rate in light was then calculated from these measurements. Rates of C02 exchange and CO2 compensation points were similarly measured at several concentrations of oxygen between 2% and 100%. The CO concentration at CO compensation point was a linear function of O2 concentration in eleven of the twelve species studied. The CO2 compensation point of corn was not affected by O2 . At 60% O2, the inhibition of rates of CO2 uptake was of the same magnitude in all species studied. The minimum rate of CO2 evolution in light was found to be at least twice the rate of CO2 evolution in the dark in ten of eleven species.

Document type: 
Thesis
File(s): 
Senior supervisor: 
C.D. Nelson
Department: 
Science: Department of Biological Sciences
Thesis type: 
(Thesis) M.Sc.

Field effect investigations in thin cadmium sulfide films.

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1967
Abstract: 

Field effect investigations on thin cadmium sulfide films have yielded a method of controlling the surface potential. The control of the surface potential is achieved by the successive evaporation of two dielectrics, GaF2 and SiO. The SiO produces donor-like surface states at the CdS surface,, while CaF2 produces acceptor-like surface states. By evaporating a thin layer of CaF2 between the CdS and SiO., the effect of the donor-like surface states on the surface conduction of CdS may be reduced. Thus, by proper choice of the CaF3 thickness, any surface potential between the limits of SiO and CaF2 may be obtained. The analysis, construction, and performance of a new evaporated, thin-film transistor capable of withstanding over 300 V is described. This thin-film transistor will switch a current of 100p.a with a gate voltage of less than 50 V, and is particularly suited as a transistor controlled switch. The large increase in operating voltage is achieved, by changes in the device geometry, material characteristics, and through careful control of the CdS surface potential by 'the method, described above. Devices were constructed with an incremental saturation resistance of 200Mi7, and a maximum operating voltage in excess of 350 V. These transistors were used to switch electro- luminescent lamps with gate voltages of 50 V in less than 0.2 msec. The transistors with semiconducting layers of CdS, utilizing CaF3 _, Si03 and Ge03 insulators and Al electrodes^ were fabricated on glass substrates by vacuum evaporation. In related experiment it was found that an evaporated CaP3 layer could be used to vary the surface potential of germanium,, and the effects of controlling the surface potential of a Ge(Li) p-i-n diode were observed. A thickness of 150 to 200 A of CaF3 appeared to restore the surface potential in the intrinsic region to the bulk value,, and thus resulted in a lower surface leakage current. - 11 -

Document type: 
Thesis
File(s): 
Senior supervisor: 
R.R. Haering
Department: 
Science: Department of Physics
Thesis type: 
(Dissertation) Ph.D.

The Anglo-Asante War of 1873-1874 : a narrative and analysis.

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1968
Abstract: 

The purpose of this study is two-fold. First, it is intended to be the narrative of a war which resulted in a radical change in British policy on the West Coast of Africa. Second, it is an attempt to assess, in military terms, the manner in which the British conducted their campaign against the Asarite in 1873-1874. The information upon which the study is based was secured primarily from the Colonial Office Confidential Print, the Sessional Papers of the British Parliament, and several edited collections of documents - notably those compiled by J.J. Crooks, G.E. Metcalfe, and C.W. Mewbury. In addition, however, works published by many of the participants themselves proved to be invaluable. Although studies published by V/.V.T. Claridge, U. Kimble, and W.E.F. Ward were used somewhat extensively, secondary materials provided little more than background information. As an introduction, the growth of British involvement on the Gold uoast and the development of the Anglo-Asante dispute is traced from the time of the first British contact with the region up to the very eve of war. The study then proceeds to examine in detail the conduct of the campaign against the Asante. Finally, because the official documents and much of the primary source material present a distorted view of the roles played by the various participants, an attempt is made to re-evaluate the - IV - performance of those participants. This approach has revealed that much of what was written of this war was either biased or incomplete. For example, Colonel R.W. Harley, the Administrator of the Gold uoast until October 1S?3, was a ?who received little recognition for his role in the war yet he is revealed as a man who accomplished much in the face of almost overwhelming odds. Similarly, the Fanti tribesmen, who were consistently reviled for their laziness and cowardice at this time, emerge in a considerably better light. In addition, the role which Captain John Glover, R.M., played in the war is proven to have been much more significant than hitherto acknowledged. Above all, Major-General Sir Garnet Uolseley, who is often referred to as one of Britain's greatest generals, is proven in this instance to have been a soldier of far less merit than previously supposed.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Alexander Peter Kup
Department: 
Arts and Social Sciences: Department of History
Thesis type: 
(Thesis) M.A.

Interband optical absorption in semiconductors.

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1968
Abstract: 

A unified, treatment of the direct. Intel-band optical absorption in semiconductors in the presen'.-;.- f external static electric and magnetic fields., is presented in tne framework of the 'effective mass approximation1. A general expression for tne absorption coefficient Is derived, wnlcn in une appr..?par at el.y which may provide the values of effective masses .in alilerent bands. The experimental conditions,, and the validity criterion for the perturbation theory., are thoroughly discussed. Some attention :.i s paid to the study of magnetic field induced surface states. Whereas suen states have been observed recently in metals, there is no experimental or theoretical evidence as to whether or not these states exist in semiconductors. We have theoretically predicted that such states do in fact exist even in semiconductors. The experimental conditions under which surface states may be detected experimentally in semiconductors are discussed. The arguments are supported with quantitative calculations,, where possible. Throughout the entire presentation we nave restricted ourselves to the study of direct band gap semiconductors. - 11 -

Document type: 
Thesis
File(s): 
Senior supervisor: 
R.R. Haering
Department: 
Science: Department of Physics
Thesis type: 
(Dissertation) Ph.D.

An analysis of the audio-lingual approach as applied to methods of teaching Russian.

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1967
Abstract: 

Problem:The term audio-lingual approach is used to denote a specific pedagogical orientation which grew out jgf_language-teaching programmes for United States military personnel during the Second World War. Its basic distinction from the traditional approaches is that language is to be taught as speech rather than as writing and grammar, as a living vehicle of communication rather than as a fossilized set of printed rules and paradigms. Language-learning, as defined audio-lingually, involves the acquisition of skills in speaking and understanding speech, while reading and writing are secondary skills based on the spoken language. Despite the acknowledged superiority over traditional methods, however, the new approach has not met with widespread acceptance. Its radical requirements have brought opposition from grammar-oriented language--teachers. Linguists themselves have challenged its effectiveness in actual classroom experience. Not all textbooks or teaching-methods purported to be based on the audio-lingual approach apply its principles to the same degree. Analysis: In considering the success of the audio-lingual approach itself we first examine its basic tenet regarding the primacy of speech and its IV claimed significance in the teaching of foreign languages. The specific challenges to this claim (especially those based on the principles of gradation and rate of learning) are then discussed as to their validity and conclusions drawn accordingly. In the next chapter the parallel development of both hearing and speaking skills is considered, together with the problem of interference from the learner's native tongue; contextual factors such as dialect, style, tempo, and vehicle of presentation are also taken into account here. Finally we turn our attention to the actual assimilation of language-material by the learner in the classroom situation. The aim in each case is to determine what factors are essential to or desirable in a successful audio-lingual teaching-method, S The second part of the thesis is devoted to an analysis of four i audio-lingual textbooks for beginning Russian students (Cornyn's Beginning Russian, Modern Russian by Dawson, Bidwell, and Humesky, Basic Conversational Russian by Fairbanks and Leed, and the A-LM Russian: Level One} on the basis of the criteria already established in the first part. The analysis covers not only the presentation and assimilation of audio--lingual skills in general, but also some of the individual difficulties involved in the mastery of those skills as far as teaching Russian to English-speaking students is concerned. Conclusions: A comprehensive summary in diagram form compares the treatment of different items in the audio-lingual approach by the four teaching-methods discussed. General conclusions are then divided into two parts: a) the recommendation that in audio-lingual methods sufficient attention be given to the learner's age and degree of literacy, his ability to understand as well as produce fluent speech, and his awareness of the finer points of contrast between the new language and his own; b) conclusions as to how well each of these considerations is treated in the different textbooks. A further final comment is made as to the success with which each of the teaching-methods, from an over-all viewpoint, applies the principles of the audio-lingual approach.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Edward R. Calhoun
Department: 
Arts and Social Sciences: Department of Modern Languages
Thesis type: 
(Thesis) M.A.

Language structure and verse structure.

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1967
Abstract: 

This thesis sets out to find ways of discussing the structure of English verse purely in terms of language without recourse to extra-linguistic metrical abstraction. Transformation-generative grammar and other linguistic theories are brought together wherever possible in order to search out linguistic tools for the analysis of verse structure. The 'structure1 of verse is taken to include verse movement and verse language, but not poetlo form or content. Section I This section sets out to develop the phonemic clause as a possible unit of verse structure. The role of Juncture and intonation in verse movement are considered as well as that of stress, and so is the connection of the perception of suprasegmentals with the underlying phrase structure. The syllable Is considered as the segmental unit of language and its traditional role In verse theory is discussed. The verse line is considered both as a graphic unit and in its relationship to spoken language. Juncture is found to be the factor common to both the phonic division of speech and the graphic division of verse. Verse is divided into two main types according to structure: metered and unmetered verse. The language elements of both metered and unmetered verse are examined together with the possible effect of breathing, and other physiological rhythms, on verse movement. Rules are postulated for the generation of a hypothetical verse line as an extension of H.B. Stookwell's rules for Intonation in the generation of a sentence. Section II In this section, six examples of unmetered verse are analysed according to Juncture divisions into phonemic clauses and are discussed according to underlying phrase structure and other linguistic features. In all six poems, a second analysis is made according to the poet's reading of the poem. A graphic recording of the voice sound was made in each case, and for the live readings, there was also a graphic recording of breath by means of a respiration curve synchronised with the voice. Conclusions The conclusions of this thesis are that verse structure can be analysed In terms of Juncture and the phonemic clause. That Juncture plays a significant part In the movement of verse and offers a practicable division point for the setting up of a unit of verse movement. That the poet's particular use of verse language is an extension of the main language. That in any physical observation of verse readings, the limitations of perception must be taken into account. That although breathing patterns as observed suggest possible connections with the verse line, no general conclusions can be drawn at this point.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Lionel Kearns
Department: 
Arts and Social Sciences: Department of English
Thesis type: 
(Thesis) M.A.