Optimal vehicle size for road-based urban public transport in developing countries

Imperial Users onl

Synthesis and polymerisation of isotopically labelled methacrylate based monomers

This thesis is concerned with the synthesis and polymerisation of isotopically labelled methacrylate based monomers. Chapter 2 describes the preparation of methyl [2-(^13)C]-and [3-(^13)C]-methacrylate via a Wittig-Homer type reaction and a diethyl malonate route respectively. The results of the free radical polymerisation of these monomers are discussed in Chapter 4. The presence of (^13)C-isotope in the resultant polymer enhanced the low intensity signals from the end groups in the (^13)C-NMR. However, more importantly, this study allowed us to investigate the presence of head to head links by observing for the first order (^13)C-(^13)C coupling from the two quaternary carbons in the polymer of methyl [2-(^13)C]- methacrylate. The findings of this study are reported in Chapter 4, Part 1.Chapter 3 describes the preparation of methyl [a-(^13)C]-(hydroxymethyl)-[3-(^13)C]-acrylate, [(^13)C(_2)]-MHMA and methyl [a-(^2)H(^2)-(hydroxymethyl).[3-(^13)C]-acrylate, [(^2)H(_4)]- MHMA monomers. The copolymeristion with methyl methacrylate and subsequent lactonisation are reported in Chapter 4, Part 2. In the (^13)C-NMR spectrum of lactonised MMA/[(^13)C(_2)]-MHMA copolymer, the signals from any residual (^13)CH(_2)OH groups were absent, indicating that lactonisation was complete under the conditions described. Chapter 5 describes the preparation of fluorinated and non-fluorinated phosphonate based methacrylate monomers to study their potential as ionic materials and extend their application as a fire retarding material. However, attempts to polymerise these monomers by either free radical or anionic methods met with little success. The successful preparation of a polymer from a non-phosphonate based methacrylate monomer indicates that perhaps the phosphonate moiety inhibits the polymerisation by being a radical acceptor

Challenges of the development of palmyrah industry in Northern province, Sri Lanka: sociological approach towards transition from traditional to modern sector

Palmyrah based industry is a traditional, family based business utilises the indigenous resources of North and Eastern provinces. This industry shows a peculiar state of growth, which is affected by sociological aspects of the environment significantly. The producers involve in the production and marketing of palmyrah based products face challenges at each phase of processes. The research problems are studied and presented on the basis of qualitative method in this research paper. Informal interviews and observations are employed in the study to identify the sociological problems of the producers. Few recommendations are suggested on the basis of the findings, to rectify the sociological challenges

Studies on the biology of Pullus xerampelinus Muls. (Coleoptera:Coccinellidae), a predator of Aspidiotus destructor Sign. (Homoptera:Coccidae), with a note on its parasite

Pullus xerampelinus Muls., a coccinellid predator of coconut scale, Aspidiotus destructor Sign was studied in the Laboratory. Its life cycle consists of the egg, four larval instars, prepupa, pupa and the adult. The description of the insect, its fecundity, feeding capacity and longevity were studied. A note on its newly recorded parasite, Aminellus indicus Kerrich is mad

Developments in the control of coconut scale Aspidiotusdestructor Sign. in Sri Lanka

Studies were commenced on an intensive biological control programme of the coconut scale, Aspidiotus destructor sign, in Sri Lanka. Out of the natural enemies of the coconut scale recorded, an aphelinid parasite Aphytis chrysomphali Mercet and two coccinellid predators, Chilocorus nigritus F. and Pullus xerampelinus Mulsant were found to be important, the latter being recorded for the first time from Sri Lanka. Other indigenous predators recorded for the first time are two coccinellids, Chilocorus circumdatus Sch., Pullus sp.? coccidivora Ayyar and a nitidulid Cebocephalus sp. Ch. nigritus and P. Xerampelinus were attacked byu parasites, Homalotylus flaminius sp. on H. flaminius was also recorded

The behaviour of Aphytis chrysomphali, a hymenopterus parasite of the coconut scale - Aspidiotus destructor, in Sri Lanka

Aphytis chrysomphali Mercet, an aphelinid parasite of the coconut scale, Aspidiotus destructor sign, was studied in the field with refference to its behavioral response to the host. When the data on parasitism collected from a single site at seven different times were analysed, only on three accasions did the parasite show a significant direct deasity -dependent response to changes in host density

Global and Gene-Specific Regulation in Freeze-Tolerant Anuran Dryophytes chrysoscelis

Cope’s Gray Treefrog, Dryophytes chysoscelis, seasonally tolerates freezing. During this process, it is subject to cellular stress from factors such as metabolic starvation, DNA damage, toxin accumulation (from cellular metabolism), and the risk of protein misfolding. Preliminary transcriptome data indicates that many mRNA transcripts vary in relative abundance within hepatocytes of D. chrysoscelis during discrete periods of warm acclimation, cold acclimation, freezing, and thawing. Physiological changes that occur in this frog are likely the result of epigenetic regulation—an alteration in gene expression that does not influence DNA sequence. This modification in gene expression can be observed by the subsequent change in relative abundance of mRNA transcripts. This thesis investigates the relative abundance of the hepatic mRNA transcripts for (1) NDUF7, a methyltransferase gene that mediates some epigenetic regulation by transferring methyl groups (global regulation) and (2) ACADV and BFAR–genes that mediate stress responses contributing to freeze tolerance (local regulation). All of the genes selected are orthologous counterparts to those found in humans. Based on preliminary transcriptome data, we hypothesized that methyltransferases important to the freezing process will be differentially regulated (either up-regulated or down-regulated) as compared to the warm condition, whereas stress genes that enhance the survivability of the frogs during freezing will be up-regulated and those that are metabolically costly will be downregulated. These results demonstrate trends in mRNA expression within four biological groups (warmacclimated, cold-acclimated, frozen, and freshly thawed) that may be relevant to the freezing process. mRNA was isolated from livers from frogs of the four biological group. cDNA was synthesized and the relative abundance of each transcript was identified using RTqPCR techniques and compared to the abundance of a housekeeper gene Dc LS-14, which served as a control. The results from the experimental groups were analyzed using ΔΔCt logarithm to calculate the fold change. The results showed that all in genes were down-regulated in expression relative to the warm-acclimated control. NDUF7 showed respective fold changes of -5.82 (cold), -4.40 (frozen), and -6.54(thawed). ACADV demonstrated negative fold changes of -3.74, -3.06, and -3.68, while BFAR had fold changes of -1.14, -1.13, and -1.78 respectively. These data indicate that global down-regulation of gene expression at the transcript level may be an important energy conservation mechanism necessary for surviving freezing and thawing in Cope’s gray treefrog

Possible impact of rising sea levels on vector-borne infectious diseases

<p>Abstract</p> <p>Background</p> <p>Vector-borne infectious diseases are a significant cause of human and animal mortality and morbidity. Modeling studies predict that changes in climate that accompany global warming will alter the transmission risk of many vector-borne infectious diseases in different parts of the world. Global warming will also raise sea levels, which will lead to an increase in saline and brackish water bodies in coastal areas. The potential impact of rising sea levels, as opposed to climate change, on the prevalence of vector-borne infectious diseases has hitherto been unrecognised.</p> <p>Presentation of the hypothesis</p> <p>Mosquito species possessing salinity-tolerant larvae and pupae, and capable of transmitting arboviruses and parasites are found in many parts of the world. An expansion of brackish and saline water bodies in coastal areas, associated with rising sea levels, can increase densities of salinity-tolerant vector mosquitoes and lead to the adaptation of freshwater vectors to breed in brackish and saline waters. The breeding of non-mosquito vectors may also be influenced by salinity changes in coastal habitats. Higher vector densities can increase transmission of vector-borne infectious diseases in coastal localities, which can then spread to other areas.</p> <p>Testing the hypothesis</p> <p>The demonstration of increases in vector populations and disease prevalence that is related to an expansion of brackish/saline water bodies in coastal areas will provide the necessary supportive evidence. However the implementation of specific vector and disease control measures to counter the threat will confound the expected findings.</p> <p>Implications of the hypothesis</p> <p>Rising sea levels can act synergistically with climate change and then interact in a complex manner with other environmental and socio-economic factors to generate a greater potential for the transmission of vector-borne infectious diseases. The resulting health impacts are likely to be particularly significant in resource-poor countries in the tropics and semi-tropics. Some measures to meet this threat are outlined.</p

Performance improvement of ad hoc networks using directional antennas

We investigate preventive link maintenance scheme to on-demand routing algorithms. The scheme of creating directional link is proposed to extend the life of link that is about to break. We see the performance improvement at network layer by using the proposed scheme. We do a comparative performance study between omni directional and directional antennas for DSR (On-demand routing protocol) using simulation with OPNET. By using directional antennas, substantial gain is achieved in terms of end-to-end delay, aggregate throughput, average data packets dropped, packet delivery ratio, and routing overhead. The proposed scheme is general and can be used with any other on-demand routing algorithms