27 research outputs found

    The <i>N</i>-myristoylome of <i>Trypanosoma cruzi</i>

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    Protein N-myristoylation is catalysed by N-myristoyltransferase (NMT), an essential and druggable target in Trypanosoma cruzi, the causative agent of Chagas’ disease. Here we have employed whole cell labelling with azidomyristic acid and click chemistry to identify N-myristoylated proteins in different life cycle stages of the parasite. Only minor differences in fluorescent-labelling were observed between the dividing forms (the insect epimastigote and mammalian amastigote stages) and the non-dividing trypomastigote stage. Using a combination of label-free and stable isotope labelling of cells in culture (SILAC) based proteomic strategies in the presence and absence of the NMT inhibitor DDD85646, we identified 56 proteins enriched in at least two out of the three experimental approaches. Of these, 6 were likely to be false positives, with the remaining 50 commencing with amino acids MG at the N-terminus in one or more of the T. cruzi genomes. Most of these are proteins of unknown function (32), with the remainder (18) implicated in a diverse range of critical cellular and metabolic functions such as intracellular transport, cell signalling and protein turnover. In summary, we have established that 0.43–0.46% of the proteome is N-myristoylated in T. cruzi approaching that of other eukaryotic organisms (0.5–1.7%)

    Main results of the first experimental campaign in the stellarator W7-X

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    A summary of the first operational phase (OP1.1) at the stellarator W7-X is given. The operational setup of heating and diagnostics as well the results of experiments are briefly described. Plasma parameters and confinement are better than expected: Te > 8 keV and Ti > 2 keV at ne ≈ 3×1019 m-3 yielding β0 ≈ 2.5 %. The results for ECR heating with X2-mode as well the ECCD are in good agreement with the theory predictions. The heating scenario with the O2-mode alone was successfully first time performed. Stellarator specific regime of core “electron root” confinement was obtained

    Methodology for the modelling of thermally activated building components in low exergy design

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    There is still an obvious and indisputable need for an increase in the efficiency of energy utilisation in buildings. Heating, cooling and lighting appliances in buildings account for more than one third of the world’s primary energy demand and there are great potentials, which can be obtained through better applications of the energy use in buildings. This thesis focuses on the development of methods and models for heat and mass transfer processes in buildings, which have a vital impact on the energy utilisation. These models can be used in optimisation procedures aiming at increasing efficiency in the energy use, i.e. at minimising consumption of the necessarily supplied high quality energy, i.e. exergy, in buildings. Through the use of the method of analysing exergy flows in buildings, similar to the analysis applied on other thermodynamic systems, such as power stations, it is possible to identify the potential of increased efficiency in energy utilisation. It has been shown that calculations based on the energy conservation and primary energy concept alone are inadequate for gaining a full understanding of all important aspects of energy utilisation processes. Thus, a method for exergy analyses, based on a combination of the first and second laws of thermodynamics, is presented and an assessment tool has been developed for a better understanding and design of energy flows in buildings. Ventilation heat losses account for a significant fraction of the overall heating energy use in buildings. The implementation of natural ventilation strategies allows for the possibility of supplying indoor space with the required fresh air volume, without any fan power. Because of the ability to create high air flows, the use of natural ventilation can be beneficial to for night cooling processes. All in all, it is important to estimate the expected air flow rates during the design and planning stage of a building. That is why a model, based on earlier published works on single sided natural ventilation on tilting windows, has been developed for natural cross ventilation conditions with tilting windows. There are also building service system solutions which can help to reduce exergy consumption caused by the heating and cooling of rooms. The thermally activated building components are examples of these systems; they use very low temperature differences between the heat carrier medium and the room to be tempered. Earlier derived models of such systems are not always satisfactory for the design of all system configuration or new regulation strategies. The developed macro element modelling (MEM) approach is based on research conducted on the modelling of dynamic heat flows in solid constructions with discrete resistances and capacitances. In this work, it has been expanded by the simultaneous modelling of heat carrier flows and used on the thermally activated components. A methodology for modelling thermally activated components has been developed and verified. Optimised resistance-capacitance (RC) networks combined to so-called macro elements are used to model the solid parts of the system, the fluid temperatures are calculated under the precondition of a linear variation of mass node temperature between the calculation nodes. It has been demonstrated and verified that the MEM method is generally suitable for modelling the dynamic behaviour of combined systems with a heat carrier flow and solid construction parts with substantial heat storage capacity

    Clean delivery practices in rural northern Ghana: a qualitative study of community and provider knowledge, attitudes, and beliefs

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    BACKGROUND: Knowledge, attitudes and practices of community members and healthcare providers in rural northern Ghana regarding clean delivery are not well understood. This study explores hand washing/use of gloves during delivery, delivering on a clean surface, sterile cord cutting, appropriate cord tying, proper cord care following delivery, and infant bathing and cleanliness. METHODS: In-depth interviews and focus group discussions were audiotaped, transcribed, and analyzed using NVivo 9.0. RESULTS: 253 respondents participated, including women with newborn infants, grandmothers, household and compound heads, community leaders, traditional birth attendants, and formally trained health care providers. There is widespread understanding of the need for clean delivery to reduce the risk of infection to both mothers and their babies during and shortly after delivery. Despite this understanding, the use of gloves during delivery and hand washing during and after delivery were mentioned infrequently. The need for a clean delivery surface was raised repeatedly, including explicit discussion of avoiding delivering in the dirt. Many activities to do with cord care involved non-sterile materials and practices: 1) Cord cutting was done with a variety of tools, and the most commonly used were razor blades or scissors; 2) Cord tying utilized a variety of materials, including string, rope, thread, twigs, and clamps; and 3) Cord care often involved applying traditional salves to the cord - including shea butter, ground shea nuts, local herbs, local oil, or “red earth sand.” Keeping babies and their surroundings clean was mentioned repeatedly as an important way to keep babies from falling ill. CONCLUSIONS: This study suggests a widespread understanding in rural northern Ghana of the need for clean delivery. Nonetheless, many recommended clean delivery practices are ignored. Overarching themes emerging from this study included the increasing use of facility-based delivery, the disconnect between healthcare providers and the community, and the critical role grandmothers play in ensuring clean delivery practices. Future interventions to address clean delivery and prevention of neonatal infections include educating healthcare providers about harmful traditional practices so they are specifically addressed, strengthening facilities, and incorporating influential community members such as grandmothers to ensure success
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