Search Results - (Author, Cooperation:A. J. Holmes)

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  1. 1
    D. P. Hibar ; J. L. Stein ; M. E. Renteria ; A. Arias-Vasquez ; S. Desrivieres ; N. Jahanshad ; R. Toro ; K. Wittfeld ; L. Abramovic ; M. Andersson ; B. S. Aribisala ; N. J. Armstrong ; M. Bernard ; M. M. Bohlken ; M. P. Boks ; J. Bralten ; A. A. Brown ; M. M. Chakravarty ; Q. Chen ; C. R. Ching ; G. Cuellar-Partida ; A. den Braber ; S. Giddaluru ; A. L. Goldman ; O. Grimm ; T. Guadalupe ; J. Hass ; G. Woldehawariat ; A. J. Holmes ; M. Hoogman ; D. Janowitz ; T. Jia ; S. Kim ; M. Klein ; B. Kraemer ; P. H. Lee ; L. M. Olde Loohuis ; M. Luciano ; C. Macare ; K. A. Mather ; M. Mattheisen ; Y. Milaneschi ; K. Nho ; M. Papmeyer ; A. Ramasamy ; S. L. Risacher ; R. Roiz-Santianez ; E. J. Rose ; A. Salami ; P. G. Samann ; L. Schmaal ; A. J. Schork ; J. Shin ; L. T. Strike ; A. Teumer ; M. M. van Donkelaar ; K. R. van Eijk ; R. K. Walters ; L. T. Westlye ; C. D. Whelan ; A. M. Winkler ; M. P. Zwiers ; S. Alhusaini ; L. Athanasiu ; S. Ehrlich ; M. M. Hakobjan ; C. B. Hartberg ; U. K. Haukvik ; A. J. Heister ; D. Hoehn ; D. Kasperaviciute ; D. C. Liewald ; L. M. Lopez ; R. R. Makkinje ; M. Matarin ; M. A. Naber ; D. R. McKay ; M. Needham ; A. C. Nugent ; B. Putz ; N. A. Royle ; L. Shen ; E. Sprooten ; D. Trabzuni ; S. S. van der Marel ; K. J. van Hulzen ; E. Walton ; C. Wolf ; L. Almasy ; D. Ames ; S. Arepalli ; A. A. Assareh ; M. E. Bastin ; H. Brodaty ; K. B. Bulayeva ; M. A. Carless ; S. Cichon ; A. Corvin ; J. E. Curran ; M. Czisch ; G. I. de Zubicaray ; A. Dillman ; R. Duggirala ; T. D. Dyer ; S. Erk ; I. O. Fedko ; L. Ferrucci ; T. M. Foroud ; P. T. Fox ; M. Fukunaga ; J. R. Gibbs ; H. H. Goring ; R. C. Green ; S. Guelfi ; N. K. Hansell ; C. A. Hartman ; K. Hegenscheid ; A. Heinz ; D. G. Hernandez ; D. J. Heslenfeld ; P. J. Hoekstra ; F. Holsboer ; G. Homuth ; J. J. Hottenga ; M. Ikeda ; C. R. Jack, Jr. ; M. Jenkinson ; R. Johnson ; R. Kanai ; M. Keil ; J. W. Kent, Jr. ; P. Kochunov ; J. B. Kwok ; S. M. Lawrie ; X. Liu ; D. L. Longo ; K. L. McMahon ; E. Meisenzahl ; I. Melle ; S. Mohnke ; G. W. Montgomery ; J. C. Mostert ; T. W. Muhleisen ; M. A. Nalls ; T. E. Nichols ; L. G. Nilsson ; M. M. Nothen ; K. Ohi ; R. L. Olvera ; R. Perez-Iglesias ; G. B. Pike ; S. G. Potkin ; I. Reinvang ; S. Reppermund ; M. Rietschel ; N. Romanczuk-Seiferth ; G. D. Rosen ; D. Rujescu ; K. Schnell ; P. R. Schofield ; C. Smith ; V. M. Steen ; J. E. Sussmann ; A. Thalamuthu ; A. W. Toga ; B. J. Traynor ; J. Troncoso ; J. A. Turner ; M. C. Valdes Hernandez ; D. van 't Ent ; M. van der Brug ; N. J. van der Wee ; M. J. van Tol ; D. J. Veltman ; T. H. Wassink ; E. Westman ; R. H. Zielke ; A. B. Zonderman ; D. G. Ashbrook ; R. Hager ; L. Lu ; F. J. McMahon ; D. W. Morris ; R. W. Williams ; H. G. Brunner ; R. L. Buckner ; J. K. Buitelaar ; W. Cahn ; V. D. Calhoun ; G. L. Cavalleri ; B. Crespo-Facorro ; A. M. Dale ; G. E. Davies ; N. Delanty ; C. Depondt ; S. Djurovic ; W. C. Drevets ; T. Espeseth ; R. L. Gollub ; B. C. Ho ; W. Hoffmann ; N. Hosten ; R. S. Kahn ; S. Le Hellard ; A. Meyer-Lindenberg ; B. Muller-Myhsok ; M. Nauck ; L. Nyberg ; M. Pandolfo ; B. W. Penninx ; J. L. Roffman ; S. M. Sisodiya ; J. W. Smoller ; H. van Bokhoven ; N. E. van Haren ; H. Volzke ; H. Walter ; M. W. Weiner ; W. Wen ; T. White ; I. Agartz ; O. A. Andreassen ; J. Blangero ; D. I. Boomsma ; R. M. Brouwer ; D. M. Cannon ; M. R. Cookson ; E. J. de Geus ; I. J. Deary ; G. Donohoe ; G. Fernandez ; S. E. Fisher ; C. Francks ; D. C. Glahn ; H. J. Grabe ; O. Gruber ; J. Hardy ; R. Hashimoto ; H. E. Hulshoff Pol ; E. G. Jonsson ; I. Kloszewska ; S. Lovestone ; V. S. Mattay ; P. Mecocci ; C. McDonald ; A. M. McIntosh ; R. A. Ophoff ; T. Paus ; Z. Pausova ; M. Ryten ; P. S. Sachdev ; A. J. Saykin ; A. Simmons ; A. Singleton ; H. Soininen ; J. M. Wardlaw ; M. E. Weale ; D. R. Weinberger ; H. H. Adams ; L. J. Launer ; S. Seiler ; R. Schmidt ; G. Chauhan ; C. L. Satizabal ; J. T. Becker ; L. Yanek ; S. J. van der Lee ; M. Ebling ; B. Fischl ; W. T. Longstreth, Jr. ; D. Greve ; H. Schmidt ; P. Nyquist ; L. N. Vinke ; C. M. van Duijn ; L. Xue ; B. Mazoyer ; J. C. Bis ; V. Gudnason ; S. Seshadri ; M. A. Ikram ; N. G. Martin ; M. J. Wright ; G. Schumann ; B. Franke ; P. M. Thompson ; S. E. Medland
    Nature Publishing Group (NPG)
    Published 2015
    Staff View
    Publication Date:
    2015-01-22
    Publisher:
    Nature Publishing Group (NPG)
    Print ISSN:
    0028-0836
    Electronic ISSN:
    1476-4687
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Keywords:
    Adolescent ; Adult ; Aged ; Aged, 80 and over ; Aging/genetics ; Apoptosis/genetics ; Brain/*anatomy & histology ; Caudate Nucleus/anatomy & histology ; Child ; Female ; Gene Expression Regulation, Developmental/genetics ; Genetic Loci/genetics ; Genetic Variation/*genetics ; *Genome-Wide Association Study ; Hippocampus/anatomy & histology ; Humans ; Magnetic Resonance Imaging ; Male ; Membrane Proteins/genetics ; Middle Aged ; Organ Size/genetics ; Putamen/anatomy & histology ; Sex Characteristics ; Skull/anatomy & histology ; Young Adult
    Published by:
    http://www.nature.com/

    Latest Papers from Table of Contents or Articles in Press
  2. 2
    Staff View
    Publication Date:
    2018-02-15
    Publisher:
    American Physical Society (APS)
    Electronic ISSN:
    1098-4402
    Topics:
    Physics
    Keywords:
    Low-Energy, Multiple-Particle Dynamics
    Published by:
    http://www.aps.org/

    Latest Papers from Table of Contents or Articles in Press
  3. 3
    J. A. Holmes, T. Gorlov, N. J. Evans, M. Plum, and S. Cousineau
    American Physical Society (APS)
    Published 2018
    Staff View
    Publication Date:
    2018-12-18
    Publisher:
    American Physical Society (APS)
    Electronic ISSN:
    1098-4402
    Topics:
    Physics
    Keywords:
    Relativistic, Multiple-Particle Dynamics
    Published by:
    http://www.aps.org/

    Latest Papers from Table of Contents or Articles in Press
  4. 4
    Staff View
    Publication Date:
    2018-07-18
    Publisher:
    The American Society for Microbiology (ASM)
    Print ISSN:
    0099-2240
    Electronic ISSN:
    1098-5336
    Topics:
    Biology
    Published by:
    http://www.asm.org/

    Latest Papers from Table of Contents or Articles in Press
  5. 5
    Bartels, M. ; Donovan, R. J. ; Holmes, A. J. ; Langridge-Smith, P. R. R. ; MacDonald, M. A. ; Ridley, T.

    College Park, Md. : American Institute of Physics (AIP)
    Published 1989
    Staff View
    ISSN:
    1089-7690
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Chemistry and Pharmacology
    Notes:
    High-resolution vacuum ultraviolet fluorescence excitation spectra of the D(O+u) ion-pair state of I2 have been obtained using a pulsed supersonic jet. Tunable vacuum ultraviolet radiation in the region 184–200 nm was produced by Raman shifting (fifth and sixth anti-Stokes) the output from a tunable excimer pumped dye laser. Vibrational constants valid up to v'=201 in the D(O+u) state have been determined.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.457258

    Articles: DFG German National Licenses
  6. 6
    Haas, F. A. ; Surrey, E. ; Holmes, A. J. T.

    [S.l.] : American Institute of Physics (AIP)
    Published 1992
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    The "hydrodynamic model'' developed by Haas, Holmes, and Lea has been extended to include all elastic collision processes between the species. The properties of the electron momentum equations are investigated in detail; the solution of these equations revealing a critical point along the source axis at which the electron drift velocity reverses direction.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.1142834

    Articles: DFG German National Licenses
  7. 7
    Holmes, A. J. T. ; McAdams, R. ; Proudfoot, G. ; Cox, S. ; Surrey, E. ; King, R.

    [S.l.] : American Institute of Physics (AIP)
    Published 1994
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    Over the past 20 years, Culham Laboratory has been involved in the development of ion sources. Initially these were positive ion systems using magnetic multipole sources for neutral beam heating in the fusion program. However, the development of high proton yield sources with a magnetic filter at Culham has led to a major program in negative ion sources based on the so-called volume-type source which has a similar design. This work has been the basis of a range of negative ion sources for industrial, defence, and fusion applications, all of which are described. A significant part of this work lies in the basic physics of these sources, both for modeling and ion beam acceleration. Numerical models of these are presented. Recently the effects of catalysts such as cesium on the discharge has been shown to cause considerable enhancement in H− and D− yield. The cesium itself also acts as a discharge component and a large source and accelerator for a pure cesium diagnostic beam has been developed. This technique is applicable to other vapors.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.1145043

    Articles: DFG German National Licenses
  8. 8
    Holmes, A. J. T. ; Green, T. S. ; Newman, A. F.

    [S.l.] : American Institute of Physics (AIP)
    Published 1987
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    Proton yields in magnetic multipole sources can be increased by the creation of a magnetic "filter'' within the discharge volume, although this may introduce nonuniformity in the plasma. We have investigated the properties of a filter which can satisfy the requirements of plasma uniformity and discharge electrical efficiency and creates a proton yield of 87% when a 60-A beam is extracted at 80 keV. A model describing the behavior of the filter is also described.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.1139417

    Articles: DFG German National Licenses
  9. 9
    Johnson, J. D. ; Holmes, A. J. T.

    [S.l.] : American Institute of Physics (AIP)
    Published 1990
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    One problem inherent in the use of small planar Langmuir probes to analyze low-density plasma is expansion of the space-charge sheath with increased probe potential due to the departure from planarity caused by a nonnegligible sheath edge. Experimental evidence showing the existence of significant edge effects in the ion saturation region of the characteristic obtained from such probes is presented. The extra ion current ΔI+ collected as a result is shown to depend on the (negative) probe potential V according to the empirical relation ΔI+∝V0.75. A theoretical justification for this is obtained. Finally, the effectiveness of the technique in eliminating the edge effect for this type of probe is demonstrated by the equivalence of ion and electron densities measured in a helium discharge.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.1141849

    Articles: DFG German National Licenses
  10. 10
    Lea, L. M. ; Holmes, A. J. T. ; Thornton, M. F. ; Naylor, G. O. R.

    [S.l.] : American Institute of Physics (AIP)
    Published 1990
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    When a suitable accelerating voltage is applied to extract negative ions from a volume production source, electrons are also extracted. If no means of suppression is utilized, the electron current in a hydrogen plasma would typically be of the order of 80–100 times the negative-ion current. In the accelerator designs in use at Culham Laboratory, electrons entering the accelerator are dumped in a trap within the second electrode at a small fraction of the beam energy. Even using this technique, a considerable amount of power would be expended unnecessarily in accelerating electrons to the trap. The suppression of electrons at the source/accelerator interface can be achieved by means of a magnetic field applied across the extraction aperture. This traps electrons, which are then collected on an electrically biased subsection of the first electrode. Experiments performed with an electromagnet configuration have shown that the electron flux entering the accelerator can be reduced as approximately the reciprocal of the square of the magnetic field strength.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.1141255

    Articles: DFG German National Licenses
  11. 11
    Nightingale, M. P. S. ; Holmes, A. J. T. ; Johnson, J. D.

    [S.l.] : American Institute of Physics (AIP)
    Published 1986
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    A dc negative ion facility has been built to study both the mechanisms controlling H− production in multipole volume sources and the design of accelerators for negative ion beams. After a 7.5-cm movement of the extraction aperture position within the ion source, the arc current and source gas pressure were optimized, and an H− current of 10 mA was extracted from a 0.5-cm2 circular aperture in a 30-s pulse from a 100-A, 90-V discharge run at 18.8 mT. This is the first operation of such sources to provide a quasi-dc current of 20 mA cm−2. The installation of an octupole electron trap in the beam forming electrode has lowered the electron current extracted simultaneously with the H− beam by approximately a factor of 4, and this has led to a low H− beam divergence. The application of a small bias voltage of up to 2 V between the beam forming electrode and the anode has reduced this electron current still further (by more than a factor of 10) while maintaining the extracted ion current. It is now possible to extract ion currents from such a source/accelerator configuration that are larger than the accompanying electron current.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.1139084

    Articles: DFG German National Licenses
  12. 12
    van Os, C. F. A. ; Kleyn, A. W. ; Lea, L. M. ; Holmes, A. J. T. ; van Amersfoort, P. W.

    [S.l.] : American Institute of Physics (AIP)
    Published 1989
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    An experimental study on the production of negative ions at a pure barium surface mounted in a multicusp bucket source is presented. The conversion efficiency, i.e., the ratio of the extracted negative-ion current and the positive-ion current incident on the surface, for deuterium and for hydrogen, have been measured as a function of source pressure, converter bias, and distance between conversion surface and extraction aperture. The conversion efficiency for deuterium is somewhat larger when compared to hydrogen. The conversion efficiencies obtained agree with a model, taking into account the concentration of hydrogen in the barium surface layers. The cross sections which were measured for the stripping of negative ions by neutral gas agreed well with values from literature. The experimentally determined divergence of the surface-produced beam was 4.5° for hydrogen and 3.6° for deuterium at an energy of 100 eV. At a source pressure of 5 mTorr, the volume-produced negative-ion current could be enhanced by 10%; for 1 mTorr this enhancement was of the order of 25%.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.1140360

    Articles: DFG German National Licenses
  13. 13
    McAdams, R. ; King, R. F. ; Newman, A. F. ; Holmes, A. J. T.

    [S.l.] : American Institute of Physics (AIP)
    Published 1990
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    The plasma characteristics of a volume negative ion source are described. An indirect measurement of the negative ion current density in the source has been made. Beam extraction measurements are used to attempt to verify the measurement in the source. The two are found to be in proportion. The difference between the two is briefly discussed.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.1141256

    Articles: DFG German National Licenses
  14. 14
    McAdams, R. ; Holmes, A. J. T. ; Nightingale, M. P. S.

    [S.l.] : American Institute of Physics (AIP)
    Published 1988
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    Beam extraction experiments have been carried out on a multicusp volume H− ion source operated in a dc mode. With an extraction aperture of 16-mm diameter, negative ion beams of up to 15 mA cm−2 have been extracted. Some experiments have been performed to investigate the physics of beam extraction from the plasma that indicate a fixed plasma boundary. The beam emittance has been measured as a function of various arc and accelerator parameters. The negative ion temperatures inferred from the emittance measurements cannot at present be explained.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.1139799

    Articles: DFG German National Licenses
  15. 15
    Holmes, A. J. T. ; Lea, L. M. ; Newman, A. F. ; Nightingale, M. P. S.

    [S.l.] : American Institute of Physics (AIP)
    Published 1987
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    Results are presented on the production of H− ions in a large (55×31×20 cm3) magnetic multipole discharge, which is sufficiently large to act as the plasma generator for a neutral beam injector. H− ion current densities up to 57 mA/cm2 have been extracted in pulses up to 3 s in length at low energies. When the discharge is operated in deuterium, a maximum D− current density of 27 mA/cm2 is obtained. The scaling laws of the H− production are consistent with production by dissociative attachment to rovibrationally excited molecules and loss by mutual recombination.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.1139312

    Articles: DFG German National Licenses
  16. 16
    Holmes, A. J. T. ; Nightingale, M. P. S.

    [S.l.] : American Institute of Physics (AIP)
    Published 1986
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    A 30-kV triode accelerator has been constructed to test the design and operating characteristics of accelerators for negative hydrogen ion beams. Incorporating both a quadrupole electron trap and an octupole electron suppressor, the accelerator has been used to extract, accelerate, and focus H− ion beams of up to current densities of 20 mA cm−2. The results suggest that this accelerator design is capable of focusing across a wide range of ion current densities (0–20 mA cm−2) and acceleration voltages (15–30 kV) using the variation of a single-gap potential to achieve the required focusing. Applying a bias voltage of up to 2 V between the beam forming electrode and the anode of the source suppresses electrons and has allowed accelerator power efficiencies of over 73% to be obtained for all ion current densities up to 20 mA cm−2 so far extracted. Initial evidence that the extracted and accelerated negative ion beam may be undergoing self-focusing is discussed.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.1139085

    Articles: DFG German National Licenses
  17. 17
    Holmes, A. J. T. ; Dammertz, G. ; Green, T. S.

    [S.l.] : American Institute of Physics (AIP)
    Published 1985
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    An investigation has been made of the yield of H− ions and electrons extracted from a magnetic multipole, or bucket, ion source as a function of the parameters of the source. Under optimum conditions the H− current density attains a value equal to half of the positive ion current density (H+3) measured at the extraction plane. The experimental results indicate that, while the H− current rises linearly with arc current, the extracted electron current shows a quadratic dependence. There is also a strong dependence of the electron current on the magnetic field applied across the extraction aperture, and source filling pressure. Probe measurements within the plasma volume show considerable axial variation of the fluxes of electrons, H− ions and H+3 ions.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.1138126

    Articles: DFG German National Licenses
  18. 18
    Wells, S. B. ; Takeiri, Y. ; Newman, A. F. ; McAdams, R. ; Holmes, A. J. T.

    [S.l.] : American Institute of Physics (AIP)
    Published 1992
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    A rf ion source with a large extraction area suitable for fusion applications is considered. The source is a metallic magnetic multipole bucket with an internal antenna to couple the rf (at a frequency of 2 MHz) to the plasma. The source is diagnosed by an array of Langmuir probes to measure uniformity, density, and temperature and a small probe accelerator to extract a negative ion beam. A two-turn antenna is found to couple more power into the plasma than a half-turn antenna. When operated as a negative ion source at low powers, the source efficiency is found to be high and not to have a strong dependence on gas pressure. An extracted negative ion current density of about 4 mA/cm2 at 7 mTorr was obtained when 3 kW of power was coupled into the plasma.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.1142839

    Articles: DFG German National Licenses
  19. 19
    Surrey, E. ; Holmes, A. J. T.

    [S.l.] : American Institute of Physics (AIP)
    Published 1990
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    Experimental data show that the minimum divergence of a positive helium ion beam does not occur at the beam perveance predicted by linear ion optics. A model is presented that introduces a third-order term into the ion optics equations, in the manner of a spherical aberration to the plasma boundary. Values of the aberration coefficient C are calculated from the data and it is shown that C∝(a/d)−1.9, where a/d is the aspect ratio of the accelerator. The contour of the plasma boundary is plotted and it is shown that the aberration leads to a flattening of the boundary at the extremes of the extraction aperture.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.1141385

    Articles: DFG German National Licenses
  20. 20
    Staff View
    ISSN:
    1432-072X
    Keywords:
    Key words Methylocaldum szegediense ; Methylocaldum tepidum ; Methylocaldum gracile ; Thermophilic methanotrophs ; 16S rRNA phylogeny ; Particulate methane monooxygenase gene
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Abstract Two methanotrophic bacteria with optimum growth temperatures above 40° C were isolated. Thermotolerant strain LK6 was isolated from agricultural soil, and the moderately thermophilic strain OR2 was isolated from the effluent of an underground hot spring. When compared to the described thermophilic methanotrophs Methylococcus capsulatus and Methylococcus thermophilus, these strains are phenotypically similar to Methylococcus thermophilus. However, their 16S rRNA gene sequences are markedly different from the sequence of Methylococcus thermophilus (∼ 8% divergence) and, together with Methylomonas gracilis, they form a distinct, new genus within the γ-subgroup of the Proteobacteria related to extant Type I methanotrophs. Further phenotypic characterisation showed that the isolates possess particulate methane monooxygenase (pMMO) but do not contain soluble methane monooxygenase. The nucleotide sequence of a gene encoding pMMO (pmoA) was determined for both isolates and for Methylomonas gracilis. PmoA sequence comparisons confirmed the monophyletic nature of this newly recognised group of thermophilic methanotrophs and their relationship to previously described Type I methanotrophs. We propose that strains OR2 and LK6, together with the misclassified thermophilic strains Methylomonas gracilis VKM-14LT and Methylococcus thermophilus IMV-B3122, comprise a new genus of thermophilic methanotrophs, Methylocaldum gen. nov., containing three new species: Methylocaldum szegediense, Methylocaldum tepidum and Methylocaldum gracile.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/s002030050527

    Articles: DFG German National Licenses