La substitution apparaît, en droit administratif français, comme une notion autonome dont l'existence fait débat. Emergeant au terme d'une démarche pointilleuse, la substitution peut être identifiée au moyen de deux critères, la carence et la volonté. Ce préalable indispensable permet de déterminer la teneur de la substitution et implique, subséquemment, de rejeter une acception étirée de la notion pour s'ouvrir à une signification resserrée mais non moins riche. Incontestablement, la recherche atteste de la diversité, non-dirimante, de l'objet d'étude. Transcendant l'observation dérangeante de cette complexité, la substitution révèle une convergence fonctionnelle déterminante. Pourtant, l'hétérogénéité apparente de l'objet d'étude conduit au constat selon lequel cette convergence est intrinsèquement dissimulée. En tout état de cause, une analyse renouvelée aboutit à la révélation progressive de cette cohérence. Si la réflexion historique permet d'expliquer et de dépasser la méfiance nourrie à l'égard de la substitution, cette étape n'est qu'une esquisse, la systématisation trouvant sa confirmation dans une justification finaliste. / In french administrative law, substitution appears as an independent notion which has been debated for a long time. Rising from a pernickety approach, substitution may be identified by two criteria : deficiency and will. This mandatory preamble helps define substitution's content and implies to reject a spread conception of the notion in order to result in a tighten and substantial meaning. Research reveals indisputable duality within the subject's study. Piercing through its disturbing complexity, substitution shows a decisive functional abundance. The visible subject's diversity however leads to point that its abundance is inherently hidden. However, a renewed analysis leads to progressively reveal this unity. Although historical reflexion explains and surpasses distrust in substitution, this step is a sketch, the general analysis is confirmed by a final proof.

The basic properties of distributivity and deletion of pure and o-substitution are investigated. The obtained results are applied to show preservation of recognizability in a number of surprising cases. It is proved that linear and recognizable tree series are closed under o-substitution provided that the underlying semiring is commutative, continuous, and additively idempotent. It is known that, in general, pure substitution does not preserve recognizability (not even for linear target tree series), but it is shown that recognizable linear probability distributions (represented as tree series) are closed under pure substitution.

No description available.

The basic properties of distributivity and deletion of pure and o-substitution are investigated. The obtained results are applied to show preservation of recognizability in a number of surprising cases. It is proved that linear and recognizable tree series are closed under o-substitution provided that the underlying semiring is commutative, continuous, and additively idempotent. It is known that, in general, pure substitution does not preserve recognizability (not even for linear target tree series), but it is shown that recognizable linear probability distributions (represented as tree series) are closed under pure substitution.

Published Article / An experiment was conducted to investigate the effects of substituting wheat flour (WF) for cassava flour (CF) on chemical composition, storage stability and sensory qualities of beef sausage. The WF in the sausage was replaced with CF at 0, 25, 50, 75 and 100% levels. Values obtained for protein content were comparable with one another. However, fibre content increased with the increase in the levels of CF in the sausage. The highest fibre content of 0.43% was recorded in sausage with 15% CF. Fat content tended to decrease with increase in the levels of CF in the sausage. Values obtained for cooking and refrigeration losses were comparable with one another. Cooking losses ranged between 1.08 - 1.85% while refrigeration loss ranged from 7.60-8.53%. Compared with the control, higher panel scores were recorded on sensory qualities for sausages containing CF. WF in beef sausage can be substituted with 100% CF without adverse effect on chemical composition, processing yield or sensory qualities. This approach will satisfy the growing demand of consumers for gluten-free meat products, thereby minimising the incidence of coeliac disease in humans.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

Demonetization is an economic tool used to reduce the size of an underground economy. Though studies on the effectiveness of demonetization have increased over the past 50 years, there is little literature on the ineffectiveness of demonetization and subsequent factors that could explain a lack of change, or an increase, in illegal activity. This paper examines past cases of demonetization to determine the effectiveness of demonetization, and investigates the incentive for foreign currency substitution as a mechanism for criminals to circumvent regulatory scrutiny. Major findings of this paper include a positive but statistically insignificant correlation between demonetization and growth in the shadow economy, and a statistically significant positive relationship between exchange rate appreciation and demonetization. Finally, this paper applies these findings to test the “Modi effect” of Indian Rupee (INR) demonetization.

Making computers automatically find the appropriate meaning of words in context is an interesting problem that has proven to be one of the most challenging tasks in natural language processing (NLP). Widespread potential applications of a possible solution to the problem could be envisaged in several NLP tasks such as text simplification, language learning, machine translation, query expansion, information retrieval and text summarization. Ambiguity of words has always been a challenge in these applications, and the traditional endeavor to solve the problem of this ambiguity, namely doing word sense disambiguation using resources like WordNet, has been fraught with debate about the feasibility of the granularity that exists in WordNet senses. The recent trend has therefore been to move away from enforcing any given lexical resource upon automated systems from which to pick potential candidate senses,and to instead encourage them to pick and choose their own resources. Given a sentence with a target ambiguous word, an alternative solution consists of picking potential candidate substitutes for the target, filtering the list of the candidates to a much shorter list using various heuristics, and trying to match these system predictions against a human generated gold standard, with a view to ensuring that the meaning of the sentence does not change after the substitutions. This solution has manifested itself in the SemEval 2007 task of lexical substitution and the more recent SemEval 2010 task of cross-lingual lexical substitution (which I helped organize), where given an English context and a target word within that context, the systems are required to provide between one and ten appropriate substitutes (in English) or translations (in Spanish) for the target word. In this dissertation, I present a comprehensive overview of state-of-the-art research and describe new experiments to tackle the tasks of lexical substitution and cross-lingual lexical substitution. In particular I attempt to answer some research questions pertinent to the tasks, mostly focusing on completely unsupervised approaches. I present a new framework for unsupervised lexical substitution using graphs and centrality algorithms. An additional novelty in this approach is the use of directional similarity rather than the traditional, symmetric word similarity. Additionally, the thesis also explores the extension of the monolingual framework into a cross-lingual one, and examines how well this cross-lingual framework can work for the monolingual lexical substitution and cross-lingual lexical substitution tasks. A comprehensive set of comparative investigations are presented amongst supervised and unsupervised methods, several graph based methods, and the use of monolingual and multilingual information.

No description available.

Student Number : 9006831D - PhD thesis - School of Chemistry - Faculty of Science / The ligand substitution reactions of aquacobalamin are fast and hence the usual inertness of the d6 Co(III) ion has been modified. It is well established that the reactions proceed through a dissociative interchange mechanism; however, previous ligand studies were performed in a KCl medium, which led to the formation of the more substitution-inert chloro complex. The kinetics of aquacobalamin were reinvestigated with the ligands N3–, NO2–, SCN–, S2O32–, OCN– and SeCN– in a NaNO3 medium. The reactions proceeded too rapidly for saturation kinetics to be observed and hence only the second-order rate constants could be obtained. These were corrected for pH and determined as a function of temperature, from which the activation parameters were determined. The donor atom of the ambidentate ligands were investigated and correlations were found between the Mulliken population on the donor atom, the energy of the highest occupied molecular orbital (HOMO) with σ symmetry, and Δ, the enthalpy of activation, and Δ, the entropy of activation, respectively. Good correlations occurred when the donor atoms were taken to be N for SCNII‡kHII‡kS– and NO2–; S for S2O32–; O for OCN– and Se for SeCN–. The effect that changing the environment of aquacobalamin has on its kinetics was observed by determining the rate constants for the reaction of pyridine with aquacobalamin in water and 70% ethanol. The rates were faster in water and the activation parameters obtained for the reaction of aquacobalamin with pyridine in 70% ethanol are larger than they are for the reaction in water. The larger ΔH‡ arises due to less bond formation between pyridine and Co in the transition state and ΔS‡ is larger because it is dominated by the freeing of the coordinated water i.e. bond breaking is the dominant process in the transition state. The effects of a bulkier ligand than water on the kinetics of aquacobalamin were investigated. The temperature dependence of the kinetics of the substitution of I– in iodocobalamin by imidazole, N3– and S2O32– was studied. Despite the increase in size of the departing ligand there is still nucleophilic participation of the incoming ligand in the transition state and hence the reaction still proceeds via an Id mechanism. In order to probe the cis-effect of the corrin in vitamin B12 derivatives, comparative studies were undertaken of the reactions of aquacobalamin and aqua-10-Xcobalamin, X = Cl, NO, NH2, where the H at C10 was replaced with an electron-donating (Cl, NH2) or electron-withdrawing (NO) group. Formation constants were obtained for aquacobalamin and aqua-10-chlorocobalamin for the substitution of coordinated H2O with various anions (N3–, NO2–, SCN–, S2O32–, OCN–, SeCN–) and neutral N-donor ligands (CH3NH3, pyridine, imidazole). The anionic ligands bind more strongly to aqua-10-chlorocobalamin than to aquacobalamin with log K values larger by between 0.10 and 0.63 (average 0.26) larger. The converse is true for the neutral N-donor ligands, where log K is smaller by between 0.17 and 0.3 (average 0.25). Semi-empirical molecular orbital (SEMO) calculations using the ZINDO/1 model on the hydroxo complexes show that charge density is delocalised from the axial donor atom to the metal and Cl. Thus the anionic ligands bind more strongly to aqua-10-chlorocobalamin because of the ability of the metal and the Cl at C10 to accept charge density from the ligand. The cobalt ion in aqua-10-chlorocobalamin is more electron rich than it is in aquacobalamin and so it is less likely to accept further electron density from a neutral axial donor ligand. This results in the stability being lower than that of aquacobalamin. The reaction kinetics of the substitution of H2O in aqua-10-chlorocobalamin were determined for the ligands N3– and pyridine. The reaction proceeds via a dissociative interchange mechanism since saturation was seen for pyridine and not for N3–. The activation parameters, ΔH‡ and ΔS‡, are lower for aqua-10-chlorocobalamin than aquacobalamin and hence it can be deduced that bond breaking between the coordinated water and the cobalt atom is more dominant in aquacobalamin. The rates of reaction are faster for aquacobalamin than they are for aqua-10-chlorocobalamin. SEMO calculations show that as the Co–O bond is stretched, the charge density on Co in aquacobalamin is always lower than that on aqua-10-chlorocobalamin, suggesting that aquacobalamin is a better electrophile towards the incoming ligand, thereby explaining the faster kinetics. Aqua-10-nitrosocobalamin was synthesised and characterised by FAB(MS), NMR and UV-vis spectroscopy. The strongly electron-withdrawing NO group has deactivated the metal ion towards ligand substitution, with neither 1.2 M pyridine nor 0.7 M N3– showing any spectroscopic evidence for the displacement of the axial H2O ligand. This provides further evidence that the electronic structure of the corrin ring can directly influence the ligand-binding properties of the metal. Aqua-10-aminocobalamin was synthesised from aqua-10-nitrosocobalamin but is unstable in solution. Hence, only a preliminary UV-vis study could be undertaken with the compound. This study shows that the shifts in the bands occur towards longer wavelengths than that of aqua-10-chlorocobalamin, suggesting that the amino group at the C10 position donates more electron density to the cobalt centre than the chloro group.