Thesis (Ph. D.)--Montana State University, 2004. / Title from PDF title page (viewed Jan. 8, 2005). Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 1993.

Thesis (Ph. D.)--University of Hong Kong, 1991.

Thesis (Ph. D.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains ix, 118 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

Thesis (MScFor)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Nine species in ten different seed source trials were evaluated with the aim of understanding their potential as exotics in improving plantation forestry in Rwanda. Assessment was based on tree growth and stem quality, juvenile-mature and trait-trait phenotypic correlations as well as the relationship of seed source performance and the locational variables of seed origin. Eucalyptus saligna, E. urophylla, Pinus maximinoi and P. tecunumanii proved to be very promising as plantation species and are highly recommended. P. patuia and Grevillea robusta are also recommended for plantation and agroforestry purposes respectively. P. caribaea and P. kesiya proved to be very poorly adapted under local conditions and should be retested if resources were available. All trials except E. urophylla, and P. maximinoi (the two had very few degrees of freedom) showed significant differences of varying degrees in different traits between seed sources indicating their potential for genetic improvement through selection and breeding. Similarly, all trials except E. urophylla, and P. maximinoi indicated significant juvenile-mature phenotypic correlations of varying degrees in different traits, with height showing strongest relationships. On average, trait-trait relationship was observed to be strongest between diameter and volume, followed by height and volume, height and branching pattern, stem form and branching pattern, stem form and height, branching pattern and volume, and diameter (and volume) and stem form in that order. Based on juvenile-mature phenotypic correlations, tree height at 15 and 16 years can be predicted as early as at three years for E. tereticornis (r :::0;.4680) and P. kesiya (r:::;0.5530) respectively, while that at 14 and 16 years in P. tecunumanii (r:::;0.4820) and P. patuia (r:::;0.5562) can be predicted using height at four years. This however may only be true where genetic and phenotypic relations are strong (as may be the case in E. tereticornis since high heritability estimates were obtained). The following additional recommendations are made under this study: To study the effect of growth rate on wood properties of very fast growing pine species; to introduce other tropical species such as E. deglupta and P. oocarpa so as to diversify species; carry out studies to better understand the effect of altitude on the adaptability of the exotic tree species in the tropical and sub tropical environments and lastly, carry out genetic tests in future so as to ascertain the obtained results on age-age and trait-trait correlations in this study. / AFRIKAANSE OPSOMMING: Nege spesies in tien verskillende saadbronproewe is geëvalueer met die doeI om hulle potensiaal as eksotiese spesies te verstaan sodat plantasie-bosbou in Rwanda verbeter kan word. Die evaluering is gebaseer op boomgroei en stamkwaliteit, jongeling-volwasse en eienskap-eienskap fenotipiese korrelasies, sowel as die verhouding tussen saadbronprestasie en die omgewingveranderlikes van saadoorsprong. Eucalyptus saligna, E. urophylla, Pinus maximinoi en P. tecunumanii blyk baie belowend te wees as plantasiespesies en word sterk aanbeveel. P. patuia en Grevillea robusta word ook aanbeveel vir die doeleindes van plantasie- en agrobosbou onderskeidelik. P. caribaea en P. kesiya blyk baie swak aangepas te wees onder plaaslike omstandighede en moes weer getoets te word, sou die hulpmiddele beskikbaar wees. Alle proewe (behalwe E. urophylla en P. maximinoi - dié twee het baie min vryheidsgrade gehad) het beduidende verskille van afwisselende grade getoon tussen saadbronne in verskillende eienskappe. Dit dui aan dat hulle potensiaal het vir genetiese verbetering deur seleksie en teling. Eweneens het alle proewe behalwe E. urophylla en P. maximinoi beduidende jongeling-volwasse fenotipiese korrelasies van afwisselende grade in verskillende eienskappe getoon, met hoogte wat die sterkste verhoudings getoon het. Oor die algemeen was die eienskap-eienskap verhouding die sterkste tussen deursnee en volume, gevolg deur hoogte en volume, hoogte en vertakkingspatroon, stamvorm en vertakkingspatroon, stamvorm en hoogte, vertakkingspatroon en volume, en deursnee Cen volume) en stamvorm, in daardie volgorde. Op grond van jongelingvolwasse fenotipiese korrelasies kan boomhoogte op 15 en 16 jaar op so vroeg as drie jaar voorspel word vir E. tereticornis Cr 0 0.4680) en P. kesiya Cr 0 0.5530) onderskeidelik, terwyl boomhoogte vir P. tecunumanii Cr 00.4820) en P. patuia Cr 0 0.5562) op 14 en 16 jaar voorspel kan word op vier jaar. Dit kan egter net juis wees waar genetiese en fenotipiese verhoudings sterk is (soos die geval kan wees met E. teretiornis, aangesien hoë erflikheidskattings verkry is). Die volgende addisionele aanbevelings word in hierdie studie gemaak: om die effek te bestudeer van die groeitempo op die houteienskappe van denspesies wat baie vinnig groei, te bestudeer; om ander tropiese spesies soos E. deglupta en P. oocarpa ook te betrek ten einde die spesies te diversifiseer; om studies uit te voer ten einde die effek van hoogte op die aanpasbaarheid van die eksotiese boomspesies in die tropiese en subtropiese omgewing beter te verstaan; en laastens, om in die toekoms genetiese toetse uit te voer ten einde die resultate wat in hierdie studie op ouderdom-ouderdom en eienskap-eienskap korrelasies verkry is, te bevestig.

Analyzes the results of M.I. Ostrovskii's theorem of inequalities which estimate the minimal edge congestion for finite simple graphs. Uses the generic results of the theorem to examine and further reduce the parameters of inequalities for specific families of graphs, particularly complete graphs and complete bipartite graphs. Also, explores a possible minimal congestion tree for some grids while forming a conjecture for all grids.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fulfillment of the requirements for the degree Master of Science Johannesburg, 2018 / Seed recalcitrance in avocado (Persea americana) has meant that avocado genetic material cannot be conserved in orthodox seed banks. Thus, biotechnological approaches have been considered for the long-term conservation of this species’ genetic material, through the cryopreservation of tissue culture-generated axillary buds. A study was conducted to develop a system for the proliferation of in vitro avocado cv. ‘Edranol’ axillary buds for the purpose of cryopreservation. Experiments were conducted to optimise avocado mother plant establishment and pretreatment. It was determined that potting soil mixes comprising of either 1:1:1 pine bark, perlite, river sand or 1:1:1 peat, perlite, river sand were suitable to culture healthy avocado mother plant seedlings. With these soil mixes approximately 2 shoots per plant developed after 11 weeks of transplanting and between 2.9 ± 0.31 and 3.37 ± 0.32 secondary shoots were produced after 5 months. Additionally, the mother plants produced well extended shoots (7.30 ± 1.29 cm; 8.77 ± 1.39 cm) with a sufficient number of axillary buds (7.75 ± 0.39; 6.33 ± 0.53), which were subsequently used as nodal explants. After surface decontamination, the establishment of an aseptic culture in vitro was successfully achieved. Six semi-solid tissue culture media were tested for the proliferation of in vitro axillary buds. Four media comprised of half (½) and full strength Murashige and Skoog (MS) medium (Murashige and Skoog, 1962), with either 0.5 or 1mg/l 6-Benzylaminopurine (BAP). Two media were based on the P. indica medium as proposed by Nel et al. (1983), and comprised of half strength MS macronutrients, full strength MS micronutrients, 2mg/l BAP and 1mg/l GA3. All media were supplemented with 3g/l Gelrite and 30g/l sucrose at pH 5.6-5.8. Physiological measurements were taken six weeks after establishment, the first, the second and the third subculture. Tissue browning, death and contamination were observed in explants cultured on the media containing 0.5mg/l BAP, suggesting that this concentration of BAP was not suitable for cv. ‘Edranol’. Additionally, hyperhydricity appeared to be associated with the media containing ½ MS, which could be attributed to mineral deficiencies. Overall, there was no significant difference in the number of shoots and axillary buds developed across all the media tested, suggesting that endogenous auxin levels were higher than the concentration of cytokinin used in the media tested. In support of this, strong apical dominance and callus formation was observed. An increase in tissue browning, death and hyperhydricity on all the media tested, coupled with a decrease in shoot length, suggested a decline in the vigour of explants in vitro. 1MS + 1mg/l BAP was selected as the most appropriate medium for the initiation of cv. ‘Edranol’ cultures, producing between 3.2 ± 0.2 and 4.9 ± 0.5 axillary buds per explant. However, hyperhydricity, browning and death were observed in explants cultured on this medium. Overall, the in vitro axillary bud explants did not behave predictably or uniformly. Thus, the system was not optimised, indicating that further study is needed for the mass multiplication of axillary buds to be used for the cryo-conservation of avocado genetic material. It is recommended that future experiments will be needed to further test tissue culture media, with a focus on the optimisation of the nutrient and plant growth regulator concentrations. Additionally, the recalcitrance of explants to the in vitro environment may have been influenced by the physiological state of the mother plants, indicating that research should be focused on the effect which the mother plants may have on the endogenous responses of the in vitro explants. / MT 2018

Malware analysts and researchers around the world are looking for innovative means of malware detection and classification. However, one concept of malware analysis that lacks focus is the rating of malware based on their feature set and capabilities. Malware severity rating is needed in order to prioritize the utilization of resources towards the analysis of a malware by an organization. This thesis proposes the utilization of threat trees for calculating malware severity using a goal oriented approach. This approach is applied to a set of sophisticated malware to study its contribution towards articulation of a useful severity rating.

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