Cette thèse se situe à l’interface entre théorie des nœuds et théorie des systèmes dynamiques. Le thème central consiste, étant donné un champ de vecteurs dans une variété de dimension 3, à considérer ses orbites périodiques, et à s’interroger sur les informations qu’elles donnent sur le champ de vecteurs et la variété initiaux.La première partie est consacrée au flot géodésique défini sur le fibré unitaire tangentd’une surface, ou d’une orbiface, à courbure constante. L’observation de certains exemples (sphère, tore, surface modulaire) suggère la conjecture suivante, due à Étienne Ghys : l’enlacement entre deux familles homologiquement nulles quelconques d’orbites périodiques est toujours négatif. En d’autres termes, le flot géodésique serait lévogyre. Quand la courbure est négative, par les travaux de David Fried sur les flots d’Anosov, cette conjecture implique une propriété étonnante et très particulière : n’importe quelle collection homologiquement nulle d’orbites périodiques borde une section de Birkhoff pour le flot géodésique, et est par conséquent la reliure d’un livre ouvert. En ce sens, cette conjecture propose une généralisation de la construction de Norbert A’Campo de livres ouverts sur les fibrés unitaires tangents. Nous proposons la démonstration de cette conjecture dans les cas du tore, des orbifolds de type (2, q, infini), et de l’orbifold de type (2, 3, 7). La seconde partie est consacrée au comportement asymptotique des invariants des nœuds formés par les orbites périodiques d’un champ de vecteur, quand la longueur de l’orbite tend vers l’infini. Le but est de définir des invariants de champs de vecteurs stables par difféomorphisme. Dans le cas particulier des nœuds de Lorenz, nous montrons que les racines du polynôme d’Alexander admettent un comportement particulier : elles s’accumulent au voisinage du cercle-unité. / This thesis deals with interactions between knot theory and dynamical systems. Givena vector field on a 3-manifold, the main idea is to study its periodic orbits from the knottheoretical point of view, and to deduce informations about the vector field and the initial manifold. The first part is devoted to the study of the geodesic flow defined on the unit tangent bundle of a surface, or an orbiface, with constant curvature. Simple examples (sphere, torus, modular surface) suggest the following conjecture, due to Ghys : the linking number of two homologically zero collections of periodic orbits is always negative. In other words, the geodesic flow on any orbiface with constant curvature is left-handed. In the negatively curved case, the work of Fried imply another surprising property : any homologically trivial collection of periodic orbits bound a Birkhoff section for the geodesic flow, and is therefore the binding of an open book decomposition. In this setting, the conjecture is a generalization of A’Campo’s construction of open book decompositions on unit tangent bundles. In our work, we prove the conjectre for the torus, for the orbifolds of type (2, q, oo), and for the orbifold of type (2, 3, 7). The second part is devoted to the asymptotic behaviour of invariants of the knots made by the periodic orbits of a vector field, when the length of the orbits tend to infinity. The goal is to define invariants of the vector field under diffeomorphism. In the case of Lorenz knots, we show that the roots of the Alexander polynomial admit an asymptotic behaviour, namely that they accumulate on the unit circle.

Thesis (M. A. Agriculture (Plant Protection)) -- University of Limpopo, 2019 / Potato (Solanum tuberosum L.) is highly susceptible to root-knot (Meloidogyne species) nematodes, with no known nematode resistant genotypes. In Limpopo Province, two cucurbitacin-containing phytonematicides had been researched and developed. The active ingredients of the cucurbitacin-containing phytonematicides are cucurbitacins, which are allelochemicals that could induce phytotoxicity on crops being protected against nematode damage. The objectives of this study were to determine: (1) mean concentration stimulation point (MCSP) of Nemarioc-AL phytonematicide on potato cultivar ꞌMondial G3ꞌ for managing M. javanica and (2) application interval of Nemarioc AL phytonematicide on potato cultivar ꞌMondial G3ꞌ. Sprouted tubers were planted in 10 cm deep/pot with each pot filled with steam-pasteurised soil and Hygromix at 3:1 (v/v) ratio in the field under microplot conditions. After 100% emergence (2 weeks), each plant was inoculated with 5 000 M. javanica eggs and second-stage juveniles (J2). Seven treatments, namely, 0, 2, 4, 8, 16, 32 and 64% Nemarioc-AL phytonematicide were arranged in a randomised complete block design, with 11 replications. In Objective 2, four treatments, namely, 1, 2, 3 and 4 weeks were arranged in randomised complete block design, with 15 replications. Plant variables and nutrient elements were subjected to the Curve-fitting Allelochemical Response Data (CARD) model to generate biological indices used to compute MCSP using the relation MCSP = Dm + Rh/2 and the overall sensitivity value (∑k). The MCSP for plant variables and nutrient elements, were empirically derived as 4.31% and 1.33%, with the ∑k of 18 and 4 units, respectively. Nematode variables and increasing concentrations of Nemarioc-AL phytonematicide exhibited negative quadratic relations where eggs, J2 in soil and roots and total population (Pf) were optimised at xv 14.43, 28.23, 23.30 and 13.55%. To conduct Objective 2 which is application interval, empirically derived MCSP value of 4.31% from Objective 1 was used. Application interval was optimised using the concept of 1, 2, 3, and 4 weeks in weeks-per-month-of-30-days. The application interval of 4.31% was established at 2.43 weeks which translated to 18 days [(2.43 weeks/4 weeks) × 30 days]. All nematode variables in Objective 2 were not significantly different at all intervals. In, conclusion Nemarioc-AL phytonematicide can be used at 4.31% concentration to control nematodes population densities without being phytotoxic to crops at 18 days application interval. / National Research Foundation (NRF) , Agricultural Research Council (ARC) and the Flemish Interuniversity Council of Belgium

Thesis (M. A. Agriculture (Plant Protection)) -- University of Limpopo, 2019 / The successful cultivation of nightshade (Solanum retroflexum) as a leafy vegetable with the nutritional potential of contributing to food security in marginalised communities of Limpopo Province could be limited by high population densities of root-knot (Meloidogyne species) nematodes. However, the use of Nemarioc-AL/AG and Nemafric-BL/BG phytonematicides in suppressing nematodes and not being phytotoxic requires the empirically-developed non-phytotoxic concentration, technically referred to as Mean Concentration Stimulation Point (MCSP). The MCSP, developed using the Curve-fitting Allelochemical Response Data (CARD) computer-based model, is crop-specific, hence it should be developed for every crop. The objective of this study was to investigate the influence of Nemarioc-AL/AG and Nemafric-BL/BG phytonematicides on growth of nightshade, accumulation of essential nutrient elements and cucurbitacin residues in nightshade leaves. Microplots were established by inserting 20-cm-diameter plastic pots into 10-cm-deep holes at 0.6 m intra-row and 0.6 m inter-row spacing. Each pot was filled with 10 000 cm3 steam-pasteurised river sand and Hygromix at 3:1. After establishment, Nemarioc-AL and Nemafric-BL phytonematicides were applied at 7-day interval, whereas, Nemarioc-AG and Nemafric-BG phytonematicides were only applied at planting. Two separate experiments for Nemarioc-AL and Nemafric-BL phytonematicides were conducted in summer (November-January) 2017/2018 under microplot conditions with each comprising treatments namely; 0, 2, 4, 8, 16, 32 and 64%, similarly, two separate experiments for the following phytonematicides, Nemarioc-AG and Nemafric-BG comprised treatments namely; 0, 2, 4, 6, 8, 10 and 12 g arranged in a randomised complete block design (RCBD), with 12 replications. The nutrient elements in leaf tissues of nightshade were analysed using the inductively coupled plasma optical emission spectrometry (ICPE-9000) while, cucurbitacin A and B were xii each quantified using the isocratic elution Shimadzu HPLC Prominence with Shimadzu CTO-20A diode array detector. Plant growth and nutrient elements variables were subjected to the CARD computer-based model to generate biological indices to generate the curves, quadratic equations and the related biological indices (Dm, Rh, k) (Liu et al., 2003). The MCSP values were calculated using the biological indices of plant or nutrient element variables which, along with increasing concentration of Nemarioc-AL, Nemafric BL, Nemarioc-AG and Nemafric-BG phytonematicides, exhibited positive quadratic relations, with R2 ≥ 25. Using cucurbitacin A and B standards, residues of Nemarioc AL/AG and Nemafric-BL/BG phytonematicides, were not detected in nightshade leaves, respectively. Dry root mass and dry shoot mass of nightshade over increasing concentration of Nemarioc-AL phytonematicide each exhibited a quadratic relationship, with the models explained by 93 and 61%, respectively. Dry root mass, dry shoot mass, plant height, chlorophyll content and stem diameter against increasing concentration of Nemafric-BL phytonematicide each exhibited positive quadratic relationships with the models explained by 95, 72, 65, 78 and 62%, respectively. Plant height, stem diameter and dry root mass against increasing concentration of Nemarioc-AG phytonematicide each exhibited positive quadratic relationships with their models explained by 93, 88 and 91%, respectively. Dry shoot mass and stem diameter against increasing concentration of Nemafric-BG phytonematicide each exhibited positive quadratic relationships with their models explained by 94 and 84%, respectively. Na, Fe and K over increasing concentration of Nemarioc-AL phytonematicide each exhibited positive quadratic relationships with their associations explained by 96, 91 and 95%, respectively. Zn over increasing concentration of Nemafric-BL phytonematicide exhibited positive quadratic relationship with the model explained by 98%. Fe over increasing concentration of Nemarioc-AG phytonematicide exhibited positive quadratic xiii relationship with the association explained by 91%. Fe, Na, K and Zn over increasing concentration of Nemafric-BG phytonematicide each exhibited positive quadratic relationships with their associations explained by 81, 90, 80 and 89%, respectively, whereas, on the contrary, Zn over increasing concentration of Nemarioc-AG phytonematicide exhibited negative quadratic relationship with the association explained by 96%. Significant (P ≤ 0.05) plant variables were subjected to CARD, to generate biological indices which were used to compute the MCSP using the relation: MCSP = Dm + Rh/2 and the overall sensitivity value (∑k). In Nemarioc-AL phytonematicide trial, MCSP = 3.02% and ∑k = 1 for plant variables, whereas, MCSP and ∑k for nutrient elements were 12.09% and 1, respectively. In Nemafric-BL phytonematicide trial, MCSP = 3.08% and ∑k = 0 for plant variables, while MCSP = 2484.14% and ∑k = 0 for nutrient elements. In Nemarioc-AG phytonematicide trial, MCSP = 3.47 g and ∑k = 0 for plant variables, whereas, for nutrient elements MCSP = 8.49 g and ∑k = 1. In Nemafric-BG phytonematicide trial, MCSP = 4.70 g and ∑k = 0 for plant variables, whereas, MCSP =723.75 g and ∑k = 1 for nutrient elements. In conclusion, the application of Nemarioc-AL/AG and Nemafric-BL/BG phytonematicides had the ability to stimulate the growth of nightshade and enhance the accumulation of the selected nutrient elements without leaving cucurbitacin chemical residues in leaf tissues of nightshade. / National Research Foundation (NRF) and the Land Bank Chair of Agriculture

Thesis (MSc. (Horticulture)) -- University of Limpopo, 2016. / Pelargonium sidoides has numerous medicinal applications, with economic potential to serve as a future cultigen in smallholder farming systems. However, it is highly susceptible to the root-knot (Meloidogyne species) nematodes, without any identifiable nematode resistant genotypes. Nemarioc-AL and Nemafric-BL phytonematicides, with cucurbitacin A and cucurbitacin B active ingredients, respectively, are being researched and developed as an alternative to synthetic nematicides at the University of Limpopo. However, since active ingredients in phytonematicides are allelochemicals, the two phytonematicides have the potential of inducing phytotoxicity on crops protected against nematode damage. The objectives of the study, therefore, were (1) to determine the non-phytotoxic concentration of Nemarioc-AL phytonematicide on plant growth of P. sidoides, and (2) to determine the non-phytotoxic concentration of Nemafric-BL phytonematicide in plant growth of P. sidoides. Cuttings were raised in 30-cm-diameter plastic pots containing 10 000 ml steam-pasteurised river sand and Hygromix-T at 3:1 (v/v) under microplot conditions in autumn (March-May) and repeated in spring (August October) 2015. After establishment each plant was inoculated with 5 000 eggs and second-stage juveniles (J2s) of M. javanica. Six treatments, namely, 0, 2, 4, 6, 8 and 10% concentrations of each phytonematicide on separate trials were arranged in a randomised complete block design, with seven replicates. At 56 days after inoculation, in Experiment 1, Nemarioc-AL phytonematicide, treatment significantly (P ≤ 0.05) affected plant height, dry root mass and root galls, contributing 62, 69 and 70% to total treatment variation of the three variables, respectively. Relative to untreated control Nemarioc-AL phytonematicide increased plant height and dry root mass by 34 to 61% xxi and 20 to 76%, respectively, with a slight decrease by 5% in plant height at the highest concentration. However, the material decreased root galls by 5 to 50%. Significant (P ≤ 0.05) plant variables were subjected to Curve fitting-allelochemical respond dosage model, to generate biological indices which were used to compute the mean concentration stimulation point (MCSP) using the relation: MCSP = Dm + Rh/2 and the overall sensitivity value (∑k). In Experiment 1, MCSP = 6.18% and ∑k = 3. Plant variables and increasing concentration of phytonematicide exhibited quadratic relations. Treatments reduced nematode variables, at all levels including at the lowest, but the effect were not different. In Experiment 2, Nemarioc-AL phytonematicide treatment effects were not significant on plant variables except for root galls, but were significant for root nematodes except for eggs. Data for plant variables in Experiment 2 were not subjected to Curve fitting-allelochemical respond dosage model because they were not significant (P ≤ 0.05). In Experiment 1, Nemafric-BL phytonematicide treatment significantly (P ≤ 0.05) affected plant height and root galls, contributing 63 and 67% to total treatment variation of the two variables, respectively. Relatively to untreated control, plant height was increased by 10 to 36%, while root galls was reduced by 2.43 to 60%. In Experiment 1, MCSP = 2.87% and ∑k = 3. Concentrations of Nemafric-BL phytonematicide significantly (P ≤ 0.05) reduced eggs, juveniles and Pf at all levels including at the lowest, but the effect were not significant different, with treatments contributing 78, 72 and 90% to the total treatment variation. In Experiment 2, Nemafric BL phytonematicide treatment effects were not significant on plant variables except for root galls, but were significant for root. In conclusion, Nemarioc-AL and Nemafric-BL xxii phytonematicides could be applied at the lowest concentration of 2% where it was shown to be effective in suppressing population densities of M. javanica. / Agricultural Research Council (ARC), National Research Fund (NRF) , Flemish Inter university Council of Belgium and Land Bank Chair of Agriculture ─ University of Limpopo

Thesis (M.Sc. (Agriculture)) --University of Limpopo, 2017 / Root-knot nematodes (Meloidogyne species) are the major soil-borne pests of tomato (Solanum lycorpesicum) plants. Due to the global withdrawal of effective chemical nematicides from the agrochemical markets, nematodes are difficult to control under the production systems. Currently, botanicals are being researched and developed as alternative to chemical nematicides with promising results, although they have challenge of phytotoxicity. The objective of this study was to determine the Mean Concentration Stimulation Point (MCSP) of Tickberry (Lantana camara) extracts for tomato plant-infected with M. javanica. Treatments consisted of six levels of L. camara extracts, namely, 0, 2, 4, 6, 8 and 10% per pot, which were arranged in a randomised complete block design, with ten replicates. Tomato seedlings were inoculated with 2500 second-stage juveniles (J2S) of M. javanica at five days after transplanting, with treatments applied at seven days after inoculation. At 56 days after inoculation, L. camara extracts had positive effects on plant height, stem diameter, number of leaves, number of fruits and fruit mass, contributing 65, 74, 61, 25 and 61% in total treatment variation (TTV), respectively, under greenhouse conditions. Under microplot conditions, treatments contributed 55, 85, 61, 36 and 85% in TTV of the respective plant variables. Under greenhouse it contributed 60, 35 and 77% and 29, 79 and 70% under microplot on dry shoot mass, dry root mass and galling index respectively. Treatments did not have any effects on soil pH and electrical conductivity (EC). Under greenhouse conditions, treatments contributed 88, 94 and 92% in TTV of nematode in roots, soil and final population, respectively, whereas under microplot conditions 94, 97 and 95% in xvii TTV of the respective nematode stages. The derived mean concentration of L. camara extracts for tomato was 5.76 and 5.31% under microplot and greenhouse conditions, respectively. The overall sensitivity of tomato plants to L. camara extracts under microplot and greenhouse were 3 and 0, respectively. In conclusion Meloidogyne species can be managed using L. camara extracts 5.31 and 5.76% under glasshouse production and field production system respectively.

My diploma work deals with the project and the construction of prototype machinery into food-processing industry which serves for knotting of frankfurther casings. This knot is make on uneatable frankfurther casing of which is shirring a peg. Diploma work I separated into several parst. In the firts part I inscribe to project of principle of knotting. In other part I prefer instrumentation components and automation function, algorithms of operating, solution to automation problems and realization of application program. This work is complete any program in Visilogic.

Thesis advisor: John A. Baldwin / We classify genus-two L-space knots in S3 and the Poincare homology sphere.This leads to the first and to-date only detection results in knot Floer homology for knots of genus greater than one. Our proofs interweave Floer-homological properties of L-space knots, the geometry of pseudo-Anosov maps, and the theory of train tracks and folding automata for braids. The crux of our argument is a complete classification of fixed-point-free pseudo-Anosov maps in all but one stratum on the genus-two surface with one boundary component. To facilitate our classification, we exhibit a small family of train tracks carrying all pseudo-Anosov maps in most strata on the marked disk. As a consequence of our proof technique, we almost completely classify genus-two, hyperbolic, fibered knots with knot Floer homology of rank 1 in their next-to-top grading in any 3-manifold. Several corollaries follow, regarding the Floer homology of cyclic branched covers, SU(2)-abelian Dehn surgeries, Khovanov and annular Khovanov homology, and instanton Floer homology. / Thesis (PhD) — Boston College, 2024. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Mathematics.

Thesis (M. Agricultural Management (Animal Production)) -- University of Limpopo, 2016 / Cultivated potato (Solanum tuberosum L.) cultigens do not have resistant genotypes to root-knot (Meloidogyne species) nematodes. Currently, efforts are underway to introgress nematode resistance in potato breeding programmes, whereas other environment-friendly nematode management strategies are being assessed in various cultigens. Nemafric-BL and Nemarioc-AL phytonematicides have being researched and developed for managing the root-knot nematode whereas Biocult Mycorrhizae are intended to enhance crop productivity through improved absorption of P, which is inherently low in most South African soils. The objectives of the study, therefore, were: (1) to determine the interactive effects of Nemacur (N), Biocult Mycorrhizae (B) and Nemarioc-AL or Nemafric-BL phytonematicide (P) on population densities of M. javanica and growth of potato plants, (2) to investigate the effects of Nemacur (N), Velum (V), Biocult Mycorhizae (B) and Nemarioc-AL or Nemafric-BL phytonematicide (P) on population densities of M. javanica and growth of potato plants. For the microplot experiment, potato cv. ‘Mondial G3’ seeds were sown in 25 cm-diameter plastic pots with 5 000 ml steam-pasteurised river sand and Hygromix-T at 3:1 (v/v) growing mixture in autumn (March-May) 2015. Pots were buried 80% deep into the soil in with 0.5 m inter-row and 0.5 m intra-row spacing. Potato cv. ‘Mondial G3’ seeds were dipped in a mixture of Mancozeb with a wettener for disease management prior to sowing. Appropriate treatments were applied soon after emergence of leaves. Each plant was inoculated by dispensing a mixture of 5 000 eggs and M. javanica J2. Eight treatments, control (N0B0P0), Nemacur (N1B0P0), Biocult (N0B1P0), phytonematicide (N0B0P1), Nemacur × Biocult (N1B1P0), Nemacur × phytonematicide (N1B0P1), Biocult × phytonematicide (N0B1P1) and Nemacur × Biocult × phytonematicide (N1B1P1), were arranged in a randomised complete block xxvi design (RCBD) with 8 replications (n= 64). Under field conditions the study was conducted in summer (October 2015 - January 2016), with 30-cm furrows dug and potato seeds placed in the soil with 30 cm inter-row and 40 cm intra-row spacing. The four treatments, namely, (1) untreated control, (2) Nemacur or Velum (3) Biocult Mycorrhizae and (4) Nemarioc-AL or Nemafric-BL phytonematicide, were arranged in RCBD, replicated three times for the Velum experiment and five times for the Nemacur experiment. At 56 days after inoculation, the second order interaction (N1B1P1) was highly significant (P ≤ 0.01) for eggs in root and total nematodes, contributing 13 and 12% to total treatment variation (TTV) of the two variables, respectively, in the Nemarioc-AL phytonematicide study. Relative to untreated control, the second order interaction (N1B1P1) reduced eggs in root and total nematodes by 42 and 36%, respectively. In both Nemarioc-AL and Nemafric-BL phytonematicide experiments, the combination of phytonematicide and Biocult Mycorrhizae reduced gall rating. Nemacur, Biocult and Nemarioc-AL phytonematicide, the treatment effects were highly significant on eggs, J2 in root and total nematodes, contributing 53, 68 and 57% to TTV of the three variables, respectively. Nemacur, Biocult and Nemafric-BL phytonematicide treatments each was not significant (P ≤ 0.05) for nematodes variables. Both treatments for Nemacur, Biocult and Nemarioc-AL or Nemafric-BL phytonematicides were significant for gall rating, contributing 92 and 70% to TTV of the variable, respectively. In Nemarioc-AL phytonematicide, relative to the untreated control, gall rating was reduced by 48 to 56%, whereas in Nemafric-BL phytonematicide the variable was reduced by 33 to 56%. In the Velum study, Biocult and Nemarioc-AL or Nemafric-BL phytonematicide, the treatment effects in both experiments were highly significant (P ≤ 0.01) on eggs in root, contributing 88% to TTV of the variable. Both treatments from Nemarioc-AL xxvii and Nemafric-BL phytonematicides had no significant effects on all plant variables measured. In microplot, the second order interaction (Nemacur × Biocult × Nemarioc-AL phytonematicide) was highly significant for nematode eggs in root and total nematode. In a three-way matrix, the N1B1P1 interaction had the highest effects on eggs, followed by Biocult alone, then Nemacur alone and then the phytonematicide. The same trend was observed in the three-way matrix for total nematodes. However, in two-way matrix for eggs, Biocult outperformed Nemacur, as was the phytonematicide on J2. In another microplot study, the second order interaction (Nemacur × Biocult × Nemafric-BL phytonematicide) was significant for J2 in soil and roots, with the three-way matrix showing, that Biocult alone had higher effects than the N1B1P1 interaction on J2 in root. A three-way matrix also showed that Nemacur was outperformed by the phytonematicide alone, Biocult alone and the interactions on J2 in soil. In conclusion, Nemarioc-AL and Nemafric-BL phytonematicides could each be used with Biocult Mycorrhizae in the management of population densities of M. javanica in potato production since the impact from Nemacur which is a synthetic nematicide does not have that much difference from that of phytonematicides interacted with Biocult Mycorrhizae. / Agricultural Research Council

No description available.

In an experiment investigating the influence of M. graminicola on rice yield, M. graminicola caused as significant yield reduction in Azucena but not in Bala indicating that this variety is tolerant. The influence of abiotic (nitrogen and water) and biotic (vesicular arbuscular mycorrhiza - VAM) factors on the nematode/rice interaction were also studied. Nitrogen stress affected Azucena plants but not Bala. Drought did not influence susceptibility of either variety but caused a significant reduction in root weight which was greater when nematodes were present in both rice varieties.