Temporal Logic Motion Planning

In this paper, a critical review on temporal logic motion planning is presented. The review paper aims to address the following problems: (a) In a realistic situation, the motion planning problem is carried out in real-time, in a dynamic, uncertain and ever-changing environment, and (b) The accomplishment of high-level specification tasks which are more than just the traditional planning problem (i.e., start at initial state A and go to the goal state B) are considered. The use of theory of computation and formal methods, tools and techniques present a promising direction of research in solving motion planning problems that are influenced by high-level specification of complex tasks. The review, therefore, focuses only on those papers that use the aforementioned tools and techniques to solve a motion planning problem. A proposed robust platform that deals with the complexity of more expressive temporal logics is also presented.Defence Science Journal, 2010, 60(1), pp.23-38, DOI:http://dx.doi.org/10.14429/dsj.60.9

The Effectiveness of NUL Programmes in Creating the Social Responsibility

The employer’s views have been sought on the quality of the National University of Lesotho (NUL) programmes in relation to addressing the concept of social responsibility. The employers’ views were sought through observing the quality of performance of the NUL graduates at the workplace and at the community engagements. The NUL designed programmes that are expected to address the societal needs, hence the reason why it is important to find out whether the programmes that prepared the graduates for the workplace have a successful outcome. A total of 150 employers in the Lesotho Ministries of Education and Training as well as Local Government and chieftainship in three of the ten districts of Lesotho formed the sample of the study. A two part questionnaire with four point likert scale of strongly agree and strongly disagree; highly satisfied and highly dissatisfied was designed to find out information on the employers’ perceptions on the performance of the NUL graduates in relation to social responsibility. Frequency counts analysis with descriptive statistics was employed to indicate the results of the study. Research results confirmed that the NUL programmes have deficiencies in moulding all graduates with competence in social responsibility. It was observed that there were graduates that have achieved the social responsibility skills, but there are those graduates who still require further training on the issue of social responsibility. It is therefore recommended that the NUL should periodically review its programmes in order to prepare a well rounded graduate that could be a community developer

Impact of Rurality on Students’ Educational Transition in Lesotho.

The students’ views, from the secondary education in the rural areas in Lesotho, have been sought on the impact of rurality in relation to their transition from secondary education to higher education (in this regards, the National University of Lesotho (NUL). The students’ views were sought through their autobiographies. Autobiographical narratives were employed because it was assumed that they are a good tool for knowing oneself better. The study was qualitative, with the adoption of a case study research design. The participating students were drawn from three of the ten Lesotho districts that are situated in the rural areas. The purpose of the research study was to find out whether studying at the university has an impact on the students who have transited from secondary education in the rural areas and whether university education assists and prepares them to achieve their intentions and to reach a successful outcome. A purposively selected number of eleven (11) students from the rural areas formed the sample of the study. A one question questionnaire was designed to collect information on the students’ experiences from their NUL studies in relation to the transition from secondary education to higher education. An interpretative analysis was employed to unveil the results of the study. The research study finds that the students have deficiencies. Secondary education has not moulded them to have a sudden engagement with their studies in higher education. Many of them still require further training in study skills in order to cope with the academic demands of higher education. It is therefore recommended that NUL should have a programme that serves as a bridge between secondary and higher education

Photosensitizing properties of non-transition metal porphyrazines towards the generation of singlet oxygen

Metallophthalocyanine complexes containing non-transition metals are very useful as sensitizers for photodynamic therapy, a cure for cancer that is based on visible light activation of tumour localized photo sensitizers. Excited sensitizers generate singlet oxygen as the main hyperactive species that destroy the tumour. Water soluble sensitizers are sought after for the convenience of delivery into the body. Thus, phthalocyanine (pc), tetrapyridinoporphyrazines (tppa) and tetramethyltetrapyridinoporphyrazines (tmtppa) with non-transition central metal atoms of Ge, Si, Sn and Zn were studied. First was the synthesis of these complexes, followed by their characterisation. The characterisation involved the use of ultraviolet and visible absorption spectroscopy, infrared spectroscopy, nuclear magnetic resonance spectroscopy, electrochemical properties and elemental analysis. Photochemical properties of the complexes were then investigated. Photolysis of these macrocycles showed two processes; -reduction of the dye and photobleaching, which leads to the disintegration of the conjugated chromophore structure of the dye. Photobleaching is the reductive quenching of the excited state of the sensitizers. The intensity of the quenching decreased progressively from tmtppa, tppa to pc metal complexes with photobleaching quantum yields, 6.6 x 10.5⁻¹, 1.8 x 10.5⁻¹ and 5.4 x 10⁻⁶ for Zntmtppa, Zntppa and Znpc, respectively. Efficiency of singlet oxygen sensitization is solvent dependent with very different values obtained for the same compound in different solvents, for example, 0.25 and 0.38 were observed as singlet oxygen quantum yields for Gepc complex in DMSO and DMF respectively. In DMSO the efficiency of ¹O₂ generation decrease considerably from pc to tppa and finally tmtppa. In water Getmtppa exhibits much higher singlet oxygen quantum yield, hence promising to be effective as a sensitizer for photodynamic therapy

Understanding project closures : objectives assessments vs. differing donor-recipient priorities : case study : Phuthiatsana Integrated Rural Development Project in Lesotho.

Thesis (M.Dev.Studies)-University of Natal, Durban, 2001.No abstract available

Photophysical properties of a water-soluble adjacently substituted bisnaphthalophthalocyanine

Spectral properties of a water soluble metal free tetracarboxyphenoxy bisnaphthalo-phthalocyanine (3) were studied in water and organic solvents. It was found that in protic solvents, complex 3 was highly aggregated. The surfactant, Triton X100, and bovineserum albumin (BSA) do not effect disaggregation while cetyl trimethylammonium chloride (CTAC) caused the molecule to disaggregate. The fluorescence quantum yields were higher in the presence of CTAC. Studying the interaction of BSA with complex 3 using fluorometry revealed that BSA is highly quenched by the latter. A 1:1 stoichiometric binding ratio between BSA and the Pc was found. Triplet quantum yields in water containing CTAC were higher than in organic solvents

Synthesis and photochemical studies of substituted adjacent binaphthalophthalocyanines

Adjacent phthalocyanines with a binaphthalo backbone and phenoxy substituents were synthesized and their photochemical properties were investigated. The adjacent phthalocyanines are the binaphthalophthalocyanines, with the phenoxy, 4-tert-butylphenoxy and the sulfophenoxy substituents, respectively and bis-binaphthalophthalocyanine which has an extended π conjugation system and larger singlet oxygen quantum yield compared to the other compounds. The presence of the phenoxy substituents as well as the binaphthalo bridge does not cause a marked difference on the fluorescing properties of these complexes when compared to zinc phthalocyanine. The binaphthalo backbone allowed the molecules to photoswitch during photolysis affording them very high photostability

Synthesis, photophysicochemical studies of adjacently tetrasubstituted binaphthalo-phthalocyanines

Adjacent binaphthalo-phthalocyanines tetra-substituted with phenoxy (4a), 4-carboxyphenoxy (4b) and 4-t-butylphenoxy (4c) groups, as well as the di-substituted 4-carboxyphenoxy (5b) have been synthesized and characterized. The photophysical and photochemical behavior of 4a-c, were compared with those of the corresponding di-substituted derivatives, (5a-c). The secondary substituents on the phenoxy ring have an influence on the aggregation of the molecules and hence on their photophysical properties. All of the complexes exhibit a relatively good conversion of energy from the triplet-excited state to the singlet oxygen. The less aggregated molecule (4c), has the highest singlet oxygen quantum yield. For all the molecules, fluorescence yields are low and they all have relatively shorter triplet lifetimes compared with the unsubstituted zinc phthalocyanine. Increasing the number of ring substituents on these rigid MPc complexes (from complexes 5 to 4) showed a general increase in the triplet state lifetimes and singlet oxygen quantum yields, and a decrease in stability

Photochemical studies of tetra-2, 3-pyridinoporphyrazines

Tetra-2,3-pyridinoporphyrazines and the corresponding water-soluble N,N′,N′′,N′′′-tetramethyl-tetra-2,3-pyridinoporphyrazine complexes, containing central metal atoms; M=Ge, Sn, Si and Zn, were synthesized and their photochemical properties were investigated. The reductive quenching of pyridinoporphyrazines excited states, enhanced relative to phthalocyanines, was considered as the first photochemical step of dyes phototransformation in dimethylformamide (DMF) and dimethylsulfoxide (DMSO) solutions under irradiation with visible light. Efficiency of singlet oxygen photosensitization decreases significantly in the row phthalocyanines, unquaternized, quaternized tetra-2,3-pyridinoporphyrazine metallocomplexes