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1,828 results on '"Mitchell, Edward"'

51. Development of a miniaturised particle radiation monitor for Earth orbit

Author

Mitchell, Edward Frank and Araujo, Henrique

Subjects
530
Abstract

Geometry and algorithm design for a novel highly miniaturised radiation monitor (HMRM) for spacecraft in medium Earth orbit are presented. The HMRM device comprises a telescopic configuration of application-specific active pixel sensors enclosed in a titanium shield, with an estimated total mass of 52 g and volume of 15 cm3. The monitor is intended to provide real-time dosimetry and identification of energetic charged particles in fluxes of up to 108 cm-2 s-1 (omnidirectional). Achieving this capability with such a small instrument could open new prospects for radiation detection in space. The methodology followed for the design and optimisation of the particle detector geometry is explained and analysis algorithms - for real-time use within the monitor and for post-processing reconstruction of spectra - are presented. Simulations with the Geant4 toolkit are used to predict operational results in various Earth orbits. Early test results of a prototype monitor, including calibration of the pixel sensors, are also reported.

Published
2013
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52. Towards a Holarctic synthesis of peatland testate amoeba ecology: Development of a new continental-scale palaeohydrological transfer function for North America and comparison to European data

Author

Amesbury, Matthew J., Booth, Robert K., Roland, Thomas P., Bunbury, Joan, Clifford, Michael J., Charman, Dan J., Elliot, Suzanne, Finkelstein, Sarah, Garneau, Michelle, Hughes, Paul D.M., Lamarre, Alexandre, Loisel, Julie, Mackay, Helen, Magnan, Gabriel, Markel, Erin R., Mitchell, Edward A.D., Payne, Richard J., Pelletier, Nicolas, Roe, Helen, Sullivan, Maura E., Swindles, Graeme T., Talbot, Julie, van Bellen, Simon, and Warner, Barry G.

Published
2018
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57. Widespread drying of European peatlands in recent centuries

Author

Swindles, Graeme T., Morris, Paul J., Mullan, Donal J., Payne, Richard J., Roland, Thomas P., Amesbury, Matthew J., Lamentowicz, Mariusz, Turner, T. Edward, Gallego-Sala, Angela, Sim, Thomas, Barr, Iestyn D., Blaauw, Maarten, Blundell, Antony, Chambers, Frank M., Charman, Dan J., Feurdean, Angelica, Galloway, Jennifer M., Gałka, Mariusz, Green, Sophie M., Kajukało, Katarzyna, Karofeld, Edgar, Korhola, Atte, Lamentowicz, Łukasz, Langdon, Peter, Marcisz, Katarzyna, Mauquoy, Dmitri, Mazei, Yuri A., McKeown, Michelle M., Mitchell, Edward A. D., Novenko, Elena, Plunkett, Gill, Roe, Helen M., Schoning, Kristian, Sillasoo, Ülle, Tsyganov, Andrey N., van der Linden, Marjolein, Väliranta, Minna, and Warner, Barry

Published
2019
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59. Towards an African Light Source

Author

Connell, Simon H., Mtingwa, Sekazi K., Dobbins, Tabbetha, Khumbah, Nkem, Masara, Brian, Mitchell, Edward P., Norris, Lawrence, Ngabonziza, Prosper, Ntsoane, Tshepo, and Winick, Herman

Published
2019
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65. Soil protistology rebooted: 30 fundamental questions to start with

Author

Geisen, Stefan, Mitchell, Edward A.D., Wilkinson, David M., Adl, Sina, Bonkowski, Michael, Brown, Matthew W., Fiore-Donno, Anna Maria, Heger, Thierry J., Jassey, Vincent E.J., Krashevska, Valentyna, Lahr, Daniel J.G., Marcisz, Katarzyna, Mulot, Matthieu, Payne, Richard, Singer, David, Anderson, O. Roger, Charman, Dan J., Ekelund, Flemming, Griffiths, Bryan S., Rønn, Regin, Smirnov, Alexey, Bass, David, Belbahri, Lassaâd, Berney, Cédric, Blandenier, Quentin, Chatzinotas, Antonis, Clarholm, Marianne, Dunthorn, Micah, Feest, Alan, Fernández, Leonardo D., Foissner, Wilhelm, Fournier, Bertrand, Gentekaki, Eleni, Hájek, Michal, Helder, Johannes, Jousset, Alexandre, Koller, Robert, Kumar, Santosh, La Terza, Antonietta, Lamentowicz, Mariusz, Mazei, Yuri, Santos, Susana S., Seppey, Christophe V.W., Spiegel, Frederick W., Walochnik, Julia, Winding, Anne, and Lara, Enrique

Published
2017
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73. Food web structure and energy flux dynamics, but not taxonomic richness, influence microbial ecosystem functions in a Sphagnum-dominated peatland

Author

Jassey, V.E.J., Petchey, Owen L., Binet, Philippe, Buttler, Alexandre, Chiapusio, Genevieve, Laggoun-Delarue, Fatima, Mitchell, Edward A.D., Barel, J.M., Jassey, V.E.J., Petchey, Owen L., Binet, Philippe, Buttler, Alexandre, Chiapusio, Genevieve, Laggoun-Delarue, Fatima, Mitchell, Edward A.D., and Barel, J.M.

Abstract

Contains fulltext : 296276.pdf (Publisher’s version ) (Closed access)

Published
2023

74. Contemporary issues, current best practice and ways forward in soil protist ecology

Author

Geisen, Stefan, Lara, Enrique, Mitchell, Edward, Geisen, Stefan, Lara, Enrique, and Mitchell, Edward

Abstract

Soil protists are increasingly studied due to a release from previous methodological constraints and the acknowledgement of their immense diversity and functional importance in ecosystems. However, these studies often lack sufficient depth in knowledge, which is visible in the form of falsely used terms and false- or over-interpreted data with conclusions that cannot be drawn from the data obtained. As we welcome that also non-experts include protists in their still mostly bacterial and/or fungal-focused studies, our aim here is to help avoid some common errors. We provide suggestions for current terms to use when working on soil protists, like protist instead of protozoa, predator instead of grazer, microorganisms rather than microflora and other terms to be used to describe the prey spectrum of protists. We then highlight some dos and don'ts in soil protist ecology including challenges related to interpreting 18S rRNA gene amplicon sequencing data. We caution against the use of standard bioinformatic settings optimized for bacteria and the uncritical reliance on incomplete and partly erroneous reference databases. We also show why causal inferences cannot be drawn from sequence-based correlation analyses or any sampling/monitoring, study in the field without thorough experimental confirmation and sound understanding of the biology of taxa. Together, we envision this work to help non-experts to more easily include protists in their soil ecology analyses and obtain more reliable interpretations from their protist data and other biodiversity data that, in the end, will contribute to a better understanding of soil ecology.

Published
2023

85. Cryocrystallographic and mechanistic studies on glycogen phosphorylase

Author

Mitchell, Edward Peter

Subjects
530.41, Enzyme crystallography
Abstract

Glycogen phosphorylase (GPb) regulates the degradation of glycogen to glucose-1-phosphate and catalyses the first step of the reaction. Many studies have provided insights into the essentials of the catalytic mechanism. Previous time resolved crystallographic work using heptenitol has revealed a putative phosphate binding site at the active site of phosphorylase. Using nojirimycin tetrazole, a transition state analogue, complexed with phosphate and both T and R state GPb crystals, this work has conclusively located the phosphate binding site and the concomitant active site conformational changes. This has confirmed the previous heptenitol results. Using R state crystals complexed with tetrazole and phosphate, data were collected to 2.5Å resolution, higher than for the original 2.8Å resolution native structure, and used to position water molecules in the R state model. Further to this, direct observation of the phosphate ion orientation was made possible using flash-frozen T state crystals to collect 1.7Å resolution data at 100K. As part of this cryocrystallographic work the relationship of cryoprotectant concentration with crystal mosaicity was established, aiding the systematic search for flash-freezing cryoprotectant conditions for all protein crystals. Collection of a new native T state data set to 1.5Å resolution was made possible using the flash-freezing technique. Refinement has produced a new higher precision native model (R factor currently 22.8%) containing additional N terminal residues (14-18) and 330 new water molecules. A molecule of glycerol, the cryoprotectant, was located at the active site. This study represents a considerable improvement over the 1.9Å resolution room temperature native data, and is also the first time such high resolution data have been collected from such a large enzyme. In a further analysis of the phosphate binding properties, a link between structure, atomic charges and the ability of a ligand to bind phosphate at the phosphorylase active site was established. In order of phosphate binding ability, the nojirimycin tetrazole, nitroglucal, glucal and glucose complexes with T state GPb and phosphate were structurally analysed. As the charge difference between the pyranose ring oxygen (or equivalent atom) and anomeric atom becomes more negative (charges estimated using MOPAC) the tendency to bind phosphate decreases. The ligand must possess a half-chair conformation as this is essential to bind phosphate; glucose, having the most negative charge difference and a full chair conformation, does not bind phosphate significantly in the crystal. A novel surface binding site for nitroglucal (covalently linked to His 73) was also located during this work. As part of an ongoing search for potential drugs for diabetes, two gluco-hydantoin inhibitors of GPb were investigated. One proved to be the best inhibitor to date, and the inhibition was rationalised using the structural results from this work. A new improved inhibitor has been proposed on the basis of these results.

Published
1994

86. A molecular mechanism for transthyretin amyloidogenesis

Author

Yee, Ai Woon, Aldeghi, Matteo, Blakeley, Matthew P., Ostermann, Andreas, Mas, Philippe J., Moulin, Martine, de Sanctis, Daniele, Bowler, Matthew W., Mueller-Dieckmann, Christoph, Mitchell, Edward P., Haertlein, Michael, de Groot, Bert L., Boeri Erba, Elisabetta, and Forsyth, V. Trevor

Published
2019
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89. Food Web Structure and Energy Flux Dynamics, But Not Taxonomic Richness, Influence Microbial Ecosystem Functions in A Sphagnum-Dominated Peatland

Author

Jassey, Vincent, primary, Petchey, Owen, additional, Binet, Philippe, additional, Buttler, Alexandre, additional, Chiapusio, Geneviève, additional, Delarue, Frédéric, additional, Laggoun-Défarge, Fatima, additional, Gilbert, Daniel, additional, Mitchell, Edward AD, additional, and Barel, Janna, additional

Published
2023
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97. Neonicotinoids and their substitutes in sustainable pest control

Author

Norton, Michael, Smagghe, Guy, Hayrabedyan, Soren, Hayrabedyan, Krassimira, Topping, Christopher John, Kahru, Anne, Hardy, Ian C.W., Mikó, Zanett, Székács, András, Pennacchio, Francesco, Geissen, Violette, de Silva, Claudia, Lipiec, Jerzy, Mitchell, Edward A.D., Rundlöf, Maj, and Walløe, Lars

Published
2023

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