174 research outputs found

    Patterns for cost-sharing of agricultural technology transfer in Nigeria

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    With recent changes in the financing and delivery of agricultural technology transfer worldwide due to inability of many governments to cope with varied needs of clients, most reforms currently being initiated by governments tend towards a pluralistic approach and financial participation of all stakeholders. One of such reforms is through cost-sharing. The authors examined stakeholders’ (extension professionals and farmers) opinions on the appropriate patterns for cost-sharing of agricultural technology transfer in Nigeria. The study was carried out in six geopolitical zones of Nigeria. Multistage random sampling technique was applied in the selection of 268 farmers and 272 extension professionals. Mean scores and t-test statistics were utilized in realizing the objectives of the study. Results show that the stakeholders’ overall opinion on the appropriate pattern for cost-sharing was for beneficiaries of service to pay specified amounts of money to extension organizations every farming season through their cooperative societies. Results further showed that farmers proved to have more ideas on the best patterns of sharing the cost of technology transfer than the extension professionals. It was concluded that for cost-sharing to be effective, all the stakeholders have to participate in decision-making and implementation processes of agricultural technology transfer in the country. Key words: cost-sharing, agricultural technology transfer, farmers, extension professionals, Nigeri

    Events, Neural Systems and Time Series

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    Different types of events occurring in computer, neural, business, and environmental systems are discussed. Though events in these different domains do differ, there are also important commonalities. We discuss the issues arising from automating complex event handling systems

    Solid state and sub-cooled liquid vapour pressures of substituted dicarboxylic acids using Knudsen Effusion Mass Spectrometry (KEMS) and Differential Scanning Calorimetry

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    Solid state vapour pressures of a selection of atmospherically important substituted dicarboxylic acids have been measured using Knudsen Effusion Mass Spectrometry (KEMS) over a range of 20 K (298–318 K). Enthalpies of fusion and melting points obtained using Differential Scanning Calorimetry (DSC) were used to obtain sub-cooled liquid vapour pressures. They have been compared to estimation methods used on the E-AIM website. These methods are shown to poorly represent – OH groups in combination with COOH groups. Partitioning calculations have been performed to illustrate the impact of the different estimation methods on organic aerosol mass compared to the use of experimental data

    Affective practices, care and bioscience: a study of two laboratories

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    Scientific knowledge-making is not just a matter of experiments, modelling and fieldwork. It also involves affective, embodied and material practices (Wetherell 2012) which can be understood together as 'matters of care' (Puig de la Bellacasa, 2011). In this paper we explore how affect spans and connects material, subjective and organisational practices, focusing in particular on the patterns of care we encountered in an observational study of two bioscience laboratories. We explore the preferred emotional subjectivities of each lab and their relation to material practice. We go on to consider flows and clots in the circulation of affect and their relation to care through an exploration of belonging and humour in the labs. We show how being a successful scientist or group of researchers involves a careful choreography of affect in relation to materials, colleagues and others to produce scientific results, subjects and workplaces. We end by considering how thinking with care troubles dominant constructions of scientific practice, successful scientific selves and collectives

    Utilization of a deoxynucleoside diphosphate substrate by HIV reverse transcriptase

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    Background: Deoxynucleoside triphosphates (dNTPs) are the normal substrates for DNA sysnthesis is catalyzed by polymerases such as HIV-1 reverse transcriptase (RT). However, substantial amounts of deoxynucleoside diphosphates (dNDPs) are also present in the cell. Use of dNDPs in HIV-1 DNA sysnthesis could have significant implications for the efficacy of nucleoside RT inhibitors such as AZT which are first line therapeutics fro treatment of HIV infection. Our earlier work on HIV-1 reverse transcriptase (RT) suggested that the interaction between the γ phosphate of the incoming dNTP and RT residue K65 in the active site is not essential for dNTP insertion, implying that this polymerase may be able to insert dNPs in addition to dNTPs. Methodology/Principal Findings: We examined the ability of recombinant wild type (wt) and mutant RTs with substitutions at residue K65 to utilize a dNDP substrate in primer extension reactions. We found that wild type HIV-1 RT indeed catalyzes incorporation of dNDP substrates whereas RT with mutations of residue K645 were unable to catalyze this reaction. Wild type HIV-1 RT also catalyzed the reverse reaction, inorganic phosphate-dependent phosphorolysis. Nucleotide-mediated phosphorolytic removal of chain-terminating 3′-terminal nucleoside inhibitors such as AZT forms the basis of HIV-1 resistance to such drugs, and this removal is enhanced by thymidine analog mutations (TAMs). We found that both wt and TAM-containing RTs were able to catalyze Pi-mediated phosphorolysis of 3′-terminal AZT at physiological levels of Pi with an efficacy similar to that for ATP-dependent AZT-excision. Conclusion: We have identified two new catalytic function of HIV-1 RT, the use of dNDPs as substrates for DNA synthesis, and the use of Pi as substrate for phosphorolytic removal of primer 3′-terminal nucleotides. The ability to insert dNDPs has been documented for only one other DNA polymerase The RB69 DNA polymerase and the reverse reaction employing inorganic phosphate has not been documented for any DNA polymerase. Importantly, our results show that Pi-mediated phosphorolysis can contribute to AZT resistance and indicates that factors that influence HIV resistance to AZT are more complex than previously appreciated. © 2008 Garforth et al

    A model for transition of 5 '-nuclease domain of DNA polymerase I from inert to active modes

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    Bacteria contain DNA polymerase I (PolI), a single polypeptide chain consisting of similar to 930 residues, possessing DNA-dependent DNA polymerase, 3'-5' proofreading and 5'-3' exonuclease (also known as flap endonuclease) activities. PolI is particularly important in the processing of Okazaki fragments generated during lagging strand replication and must ultimately produce a double-stranded substrate with a nick suitable for DNA ligase to seal. PolI's activities must be highly coordinated both temporally and spatially otherwise uncontrolled 5'-nuclease activity could attack a nick and produce extended gaps leading to potentially lethal double-strand breaks. To investigate the mechanism of how PolI efficiently produces these nicks, we present theoretical studies on the dynamics of two possible scenarios or models. In one the flap DNA substrate can transit from the polymerase active site to the 5'-nuclease active site, with the relative position of the two active sites being kept fixed; while the other is that the 5'-nuclease domain can transit from the inactive mode, with the 5'-nuclease active site distant from the cleavage site on the DNA substrate, to the active mode, where the active site and substrate cleavage site are juxtaposed. The theoretical results based on the former scenario are inconsistent with the available experimental data that indicated that the majority of 5'-nucleolytic processing events are carried out by the same PolI molecule that has just extended the upstream primer terminus. By contrast, the theoretical results on the latter model, which is constructed based on available structural studies, are consistent with the experimental data. We thus conclude that the latter model rather than the former one is reasonable to describe the cooperation of the PolI's polymerase and 5'-3' exonuclease activities. Moreover, predicted results for the latter model are presented
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