Att utveckla pålitlig och säker mjukvara är av stor vikt gällande inbyggda system, och i synnerhet mjukvara som hanterar kritiska tjänster såsom fordonsstyrning. En stor utmaning vid utveckling av inbyggda system är att hantera minnessäkerheten samtidigt som prestandan kvarhålls, ett område där äldre programspråk ofta uppvisar brister som kan leda till säkerhetsrisker och i vissa fall systemkrascher. Denna uppsats undersö- ker möjligheten att använda det relativt nya programspråket Rust i inbyggda system och jämför Rust med det väletablerade språket C. Med hjälp av en mikrokontroller (ESP32-C3-DEVKIT-RUST1), MQTT för kommunikationshantering och de angivna programspråken implementeras en prototyp av ett system för att styra fordon via WiFi. Prototyperna i Rust och C jämförs sedan kvantitativt och kvalitativt. Den kvantitativa jämförelsen fokuserar på prestanda och den kvalitativa jämförelsen på våra upplevelser kring att utveckla systemen i de två programspråken. Resultaten visar på skillnad i den kvantitativa mätningen där C var 15% snabbare samt hade en mer konsekvent exekveringstid. Trots den begränsning givet de bibliotek som finns tillgängligt för Rust anser vi att programspråket är att föredra sett till utvecklingsmiljön, kompilatorn och dokumentation. / To develop reliable and secure software is of great importance regarding embedded systems, and especially software that handles critical functionality such as control systems. A major challange for embedded systems is to manage memory security while maintai- ning performance, an area where older programming languages often show deficiencies that may lead to security risks and in some cases even system crashes. This paper explo- res the possibility to use Rust for embedded systems, and compare this programming language with the already established language C. With the help of a microcontroller (ESP32-C3-DEVKIT-RUST1), MQTT for communication management, and the spe- cified programming languages a prototype of a system for controlling vehicles via Wifi is implemented. The prototypes in Rust and C are then used in a quantitative and qualitative comparison. The quantitative comparison focuses on the performance and the qualitative comparison on the experiences from developing the system in the programming languages. The results shows differencies in the quantitative measurement where C was 15% faster while having a more consistent time of execution. Despite the limitation of available libraries for Rust, we consider the programming language preferable in the terms of environment for development, compiler and documentation.

Phakopsora pachyrhizi H. Syd and P. Syd, the causal organism of soybean rust (SBR) was first reported in Japan in 1902. In 1934 the pathogen was found in several other Asian countries and as far south as Australia. In India, SBR was first reported on soybeans in 1951. There have been several early reports of SBR in equatorial Africa but the first confirmed report of P. pachyrhizi on the African continent was in 1996 from Kenya, Rwanda and Uganda. Since then, the pathogen has spread south with reports from Zambia and Zimbabwe in 1998 and in Mozambique in 2000. In February 2001, P. pachyrhizi was first detected on soybeans near Vryheid, in Northern KwaZulu-Natal, South Africa (SA). As the season progressed, the disease was observed in other parts of the province, and epidemic levels were found in the Cedara, Greytown, Howick and Karkloof production regions. Soybean rust subsequently spread to Amsterdam and Ermelo in the Highveld region of SA. The disease reappeared in SA in March 2002. It is now established that the pathogen is a threat to soybean production in the country with yield losses in the region of 10-80%. A literature review on SBR investigating the taxonomy of the pathogen, its morphology, symptoms, host range, infection process, epidemiology, control options and the economic importance of P. pachyrhizi was complied to provide the necessary background information to conduct research under local conditions and to assist in interpretation of results of experiments. Epidemiological trials were conducted at the University of KwaZulu-Natal under controlled environmental conditions in a dew chamber and conviron. Development of P. pachyrhizi on the susceptible cultivar (LS5995) was quantified in combinations of seven temperatures (15,19,21,24,26,28 and 30°C) and five leaf wetness durations (LWD) (6,9,12,14 and 16hrs) at three relative humidities (RH) (75%, 85% and 95%). Studies indicate that optimum temperature for uredospore infection is 21-24°C with a LWD greater than 12hrs and RH 85-95%. The number of pustules as well as lesion size on the abaxial and adaxial leaf surface increased with increasing LWD at all the RH values tested. Infection did not occur on plants incubated at 15°C and 30°C at 85% or 95%RH whereas at 75%RH infection did not occur on plants incubated at 15°C, 19°C and 30°C regardless of LWD. Number of pustules per lesion produced at 75%, 85% and 95%RH was highest at 24°C and showed a gradual increase with increasing LWD. Lesion size on both leaf surfaces increased after 12hrs LWD at 24°C at 75% and 85%RH whereas at 95%RH lesion size increased after 14hrs LWD at 24°C. Exposure of uredospores to ultraviolet light which is equivalent to ultraviolet C (sunlight) which is < 280nm, shows a decrease in germination (7%). Under continuous darkness, the germination percentage was found to range from 58% after 48 hrs. Germination was found to peak at 16hrs in darkness with a gradual decrease as time increased whereas germination under ultraviolet light was highest after 6hrs with a gradual decrease with increased exposure to light. Germ tube lengths were found to be shorter when exposed to ultraviolet light (107µm) compared to controls kept in the dark (181µm). Results obtained clearly show a negative effect of ultraviolet light on the germination and germ tube length of uredospores. A 0.1 ml suspension of uredospores on 1.25% water agar Petri dishes was exposed to cycles of 14h ultraviolet light and 10h darkness for 48h. Results indicate an increase in germination percentage of uredospores when exposed to 10h of darkness following a 14h period under ultraviolet light. Controlled environmental studies were conducted to determine alternative hosts of P. pachyrhizi in SA. The control used in this experiment was Prima 2000, a susceptible cultivar to soybean rust. Seven legume plants [Cajanus cajan (L.) Huth, Glycine max (L.) Merr, Lablab purpureus (L.) Sweet, Lupinus angustifolius (L.) Finnish, Phaseolus vulgaris (L.), Pueraria lobata (M&S) Wild and Vigna unguiculata (L.) Walp] and three dry bean lines (Bonus; OPS-RS2 and PAN 159) showed typical SBR symptoms when rated after 21 days post inoculation with uredospores for percentage disease severity. Disease severity was significantly different within the alternative hosts, but G. max, P. vulgaris and P. lobata were not significantly different from Prima 2000 (control). A uredospore suspension of 2.5 x 10(5) uredospores ml(-1) from plants that showed typical SBR symptoms was made and inoculated on to Prima 2000, a susceptible soybean cultivar. Uredospores from pustules on G. max, L. purpureus, L. angustifolius, P. vulgaris, P. lobata, V. unguiculata, Bonus and PAN 159 produced viable uredospores on PRIMA 2000. These plants are considered alternative hosts of P. pachyrhizi. Effect of leaf age on susceptibility of soybean to SBR was tested under controlled environmental conditions. Mean number of lesions as well as lesion size were greater on younger leaves than on older leaves of plants at the same physiological age. Plants at the early vegetative and reproductive stages had a significantly lower number of lesions as well as a smaller lesion size. Plants at the V6 and R1 growth stages were significantly more susceptible to P. pachyrhizi than plants at other developmental stages. Trichoderma harzianum Rifai, Eco-77® a commercial biological control product, was evaluated for its efficacy as a biological control agent of P. pachyrhizi. Trichoderma harzianum sprayed at the standard concentration on infected soybean plants was significantly more effective in controlling P. pachyrhizi than plants sprayed at 1/2X and 2x the standard concentration. This was noted in both Trial 1 and 2. Data indicate that spraying the filtrate two days after inoculation produces less disease. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

Call number: LD2668 .T4 1952 H8 / Master of Science

Call number: LD2668 .T4 1959 E41

Call number: LD2668 .T4 1960 D73

LD2668 .T4 1962 S57

Master of Science / Department of Agronomy / Guihua Bai / Stem rust, caused by Puccinia graminis f. sp. tritici, has successfully prevented rust epidemics by Deployment of resistant cultivars in the past several decades. Unfortunately, race TTKS (termed Ug99) has defeated most stem rust resistance genes existing in commercial cultivars. Sr40, a stem rust resistance gene from Triticum timopheevii ssp. araraticum, was transferred to wheat and provides effective levels of seedling and adult plant resistance against Ug99. To characterize Sr40 in wheat, two mapping populations were developed from the crosses RL6088 / Lakin and RL6088 / 2174. RL6088 is an Ug99-resistant parent with Sr40. Since race TTKS is a quarantined pathogen, a US stem rust isolate RKQQ that is avirulent to Sr40 was used to evaluate the rust resistance in the F[subscript]2 and F[subscript]2:3 populations at the seedling stage. A total of 83 simple sequence repeats (SSR) primers on chromosome 2B were used to screen the parents for polymorphism. Each F[subscript]2 population was analyzed with the markers polymorphic between two parents. Marker Xwmc344 was the most closely linked to Sr40, at 0.7 cM proximal, in the linkage map constructed from the population RL6088 / Lakin, while Xwmc474 and Xgwm374 were also tightly linked. Xwmc474 was mapped 2.5 cM proximal to Sr40 in the RL6088 / 2174 population. Xwmc474 and Xwmc661 were flanking markers for Sr40 in both populations. Markers linked to Sr40 will be useful for marker-assisted integration of Sr40 into elite wheat breeding lines. In addition, a unknown stem rust resistance gene from another source, OK01307, a breeding line from Oklahoma State University shows partial resistance to Ug99, and was characterized using SSRs in this study. Two mapping populations were developed from cross OK01307 / Chinese Spring and OK01307 / LMPG-6. A total of 1300 SSR primers were screened for polymorphism between OK01307 and Chinese spring, and 1000 SSR primers were screened for polymorphism between OK01307 and LMPG-6. Polymorphic primers between parents and between bulks were used to screen the corresponding population. One Sr gene in OK01307 was mapped on chromosome 1BS of the both populations, which was closely linked to Sr24. Whether the gene is Sr24 per se or a new Sr gene that closely linked to Sr24 needs further investigation.

No description available.

Dissertation (PhD Agric)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Chrysanthemoides monilifera ssp. monilifera is a shrub indigenous to South Africa, which has become a serious weed of native vegetation in Australia. Endophyllum osteospermi is a microcyclic, autoecious, rust fungus that induces witches' brooms on C. monilifera ssp. monilifera. This rust is considered as a candidate biocontrol agent for use against C. monilifera ssp. monilifera in Australia. The vegetative growth and reproductive output of healthy branches on bushes with different levels of E. osteospermi infections were measured at three sites. The growth of healthy branches on infected bushes was 26- 81% less than that of healthy branches on uninfected bushes. The number of buds, flowering capitulae, fruiting capitulae, and cypselas on healthy branches of infected bushes was 35-75%, 45-90%, 15-99%, and 15-90% less, respectively, than those on uninfected bushes. At five sites, the infection levels and number of witches' brooms were determined every two months. The increase in number of witches' brooms per bush ranged between o and 282 within one year, with an average increase per bush of28 (SE ± 4.8) and 39 (SE ± 9.2) during two years. The average simple interest rate (rs) increase of infection levels for all bushes was 0.015 month-I (s.e. ± 0.0041, n = 72) and 0.0098 month" (s.e. ± 0.0073, n = 43) during two years. Aecidioid teliospores germinated between 10 and 20oe, with 15°e as optimum. Light, and particularly near-uv light, stimulated germination. A period of 6 to 8 hours of light was needed to obtain optimum germination levels. The temperature requirements for basidiospore development differed from that of aecidioid teliospore germination. Optimum was at 15°e, but a rapid decrease in basidiospore production occurred at higher temperatures, few developed at 19°e. Two nuclear divisions occurred within 12 hours of germination to produce a metabasidium with three or four nuclei. A third nuclear division occurred in the basidiospores between 24 and 48 hours. Plants inoculated under controlled conditions took 5 to 24 months before witches' brooms began to develop. A Geographic Information System (GIS) approach was used to model the potential distribution of E. osteospermi in South Africa, based on monthly average climate surfaces with parameters derived from the above experiments. The same model was applied to Australia to suggest a potential distribution of the rust if released in Australia. This potential distribution was similar to one generated using the climate matching computer programme CLIMEX©, but gave greater spatial accuracy. Both approaches indicate that E. osteospermi should establish in temperate Australia. Chrysanthemoides species, as well as other South African asteraceaus plants, were monitored for E. osteospermi between 1992 and 2003. Endophyllum osteospermi was recorded on C. monilifera ssp. monilifera, C. monilifera ssp. pisifera, C. monilifera ssp. rotundata, C. monilifera ssp. canescens, C. monilifera ssp. subcanescens, C. incana, an undescribed taxon of Chrysanthemoides, Osteospermum ciliatum, 0. polygaloides and 0. potbergense. Endophyllum dimorphothecae sp. nov. is described on Dimorphotheca cuneata. Aecidium elytropappi, which was recorded on Elytropappus rhinocerostis and Stoebe plumose, is transferred to Endophyllum as E. elytropappi comb. nov. Germination of aecidioid teliospores and penetration by basidiospores were observed on the surface of excised leaves of 32 plant species at 4 days after inoculation. Germinating aecidioid teliospores aborted on 14 plant species, whilst no penetration was attempted on a further 12. Penetration only occurred on 9. Therefore only these 9 plant species need to undergo traditional host specificity testing. Pending these results, E. osteospermi could be safely released in Australia for the biological control of C. monilifera ssp. monilifera. / AFRIKAANSE OPSOMMING: Chrysanthemoides monilifera ssp. monilifera 'n meerjarige wat inheems in Suid Afrika is, het 'n belangrike onkruid in Austalië geword. Endophyllum osteospermi 'n mikrosikliese, autoecious roesswam, induseer heksebesems op C. monilifera ssp. monilifera. Hierdie roesswam word as 'n potensiële biologiese beheeragent teen C. monilifera ssp. monilifera in Austalië beskou. Die vegetatiewe groei en voortplanting van gesonde takke op struike met verskillende vlakke van E. osteospermi infeksies is by drie lokaliteite gemeet. Groei van gesonde takke op geinfekteerde bosse was 26-81 % minder as die van gesonde takke op ongeïnfekteerde bosse. Die aantalokselknoppe, blommende capitulum, vrugdraende capitulum en pitvrugte op individuele gesonde takke van geïnfekteerde bosse was onderskeidelik 35-75%, 45-90%,15-99%, en 15-90% minder, as die op ongeïnfekteerde bosse. By vyf lokaliteite is die infeksievlakke en die aantal heksebesems elke twee maande vasgestel. Die toename in heksebesems van elke plant was tussen 0 en 282 binne eenjaar, met 'n gemmidel van 28 (SE ± 4.8) en 39 (SE ± 9.2) geduurende twee jaare. Die gemiddelde eenvoudige rentekoers (rs) toename in infeksievlakke van al die struike was 0.015 maand" (s.e. ± 0.0041, n = 72) en 0.0098 maand-1 (s.e. ± 0.0073, n = 43) gedurende twee jaare. Ontkieming van aecidioidteliospore het tussen 100e en 200e met 15°e as die optimum. Lig en veral naby-uv lig het ontkieming gestimuleer, terwylontkieming relatief swak was onder donker toestande. 'n Periode van 6 tot 8 uur lig was nodig vir optimale ontkiemingsvlakke. Die temperatuurvereistes vir basidiospoor ontwikkeling het verskil van die van aecidioid teliospoor ontkieming. Optimale was by 15°e, maar 'n vinnige afname in basidiospoorproduksie het by hoër temperature voorgekom, min het by 19°e voorgekom. Twee kernverdelings het binne 12 ure van die begin van ontkieming voorgekom om 'n metabasidium te produseer met drie of vier kerne. 'n Derde kern verdeling het in die basidiospore tussen 24 en 48 uur voorgekom. Plante wat onder beheeerde toestande geïnokuleer is het heksebesems 5 tot 24 maande na inokulasie ontwikkel. 'n Geografiese Inligtings Sisteem (GIS) benadering is gebruik om 'n model vir die potensiële verspreiding van E. osteospermi in Suid Afrika te ontwikkel, gebasseer op die maandelikse gemiddelde klimaatoppervlaktes met parameters wat vanaf bogenoemde eksperimente verkry is. Dieselfde model is in Austalië toegepas om 'n potensiële verspreiding van die roesswam voor te stel. Hierdie potensiële verspreiding was soortgelyk aan 'n program wat met die klimaats vergelykende rekenaarsprogram CLIMEX© ontwikel is, maar dit het groter ruimtelike akkuraatheid gemaak. Beide benaderings het aangedui dat E. osteospermi in Austalië behoort te vestig. Chrysanthemoides spesies, asook ander inheemse plante van die Asteraceae, is tussen 1992 en 2003 vir die voorkoms van E. osteospermi in Suid Afrika waargeneem. Endophyllum osteospermi is op C. monilifera ssp. monilifera, C. monilifera ssp. pisifera, C. monilifera ssp. rotundata, C. monilifera ssp. canescens, C. monilifera ssp. subcanescens, C. incana, 'n onbeskryfde taxon van Chrysanthemoides, Osteospermum ciliatum, a. polygaloides en a. potbergense waargeneem. Endophyllum dimorphothecae sp. nov. is beskryf op Dimorphotheca cuneata. Aecidium elytropappi, wat op Elytropappus rhinocerostis en Stoebe plumosa voorkom, is by Endophyllum ingesluit as E. elytropappi comb. nov. Ontkieming van aecidioidteliospore en penetrasie deur basidiospore op die oppervlak van verwyderde blare van 32 plant spesies 4 dae na inokulasie is waargeneem. Ontkiemende aecidioidteliospore het op 14 toets plant spesies ge-aborteer, terwyl geen penetrasie op 'n verdere 12 gepoog is nie. Penetrasie het slegs op 9 voorgekom. Derhalwe hoef slegs die 9 plant spesies tradisionele gasheer spesifisiteitstoetse te ondergaan. Afhangende van die resultate kan E. osteospermi dus met veiligheid in Austalië vir die biologiese beheer van C. monilifera ssp. monilifera vrygelaat word.

published_or_final_version / Botany / Master / Master of Science