Search Results - (Author, Cooperation:S. C. Parker)
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1Latest Papers from Table of Contents or Articles in PressG. Vahedi ; Y. Kanno ; Y. Furumoto ; K. Jiang ; S. C. Parker ; M. R. Erdos ; S. R. Davis ; R. Roychoudhuri ; N. P. Restifo ; M. Gadina ; Z. Tang ; Y. Ruan ; F. S. Collins ; V. Sartorelli ; J. J. O'Shea
Nature Publishing Group (NPG)
Published 2015Staff ViewPublication Date: 2015-02-18Publisher: Nature Publishing Group (NPG)Print ISSN: 0028-0836Electronic ISSN: 1476-4687Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsKeywords: Animals ; Arthritis, Rheumatoid/*genetics/immunology/pathology ; Basic-Leucine Zipper Transcription Factors/metabolism ; Cell Differentiation/genetics ; Cell Lineage/genetics ; Enhancer Elements, Genetic/*genetics ; Gene Expression Regulation/genetics ; Genetic Predisposition to Disease/genetics ; Janus Kinase 3/antagonists & inhibitors ; Mice ; Mice, Inbred C57BL ; Piperidines/pharmacology ; Pyrimidines/pharmacology ; Pyrroles/pharmacology ; RNA, Untranslated/genetics ; T-Lymphocytes, Helper-Inducer/immunology/*metabolism/*pathology ; Transcription, Genetic/genetics ; p300-CBP Transcription Factors/metabolismPublished by: -
2Latest Papers from Table of Contents or Articles in PressJ. W. Ho ; Y. L. Jung ; T. Liu ; B. H. Alver ; S. Lee ; K. Ikegami ; K. A. Sohn ; A. Minoda ; M. Y. Tolstorukov ; A. Appert ; S. C. Parker ; T. Gu ; A. Kundaje ; N. C. Riddle ; E. Bishop ; T. A. Egelhofer ; S. S. Hu ; A. A. Alekseyenko ; A. Rechtsteiner ; D. Asker ; J. A. Belsky ; S. K. Bowman ; Q. B. Chen ; R. A. Chen ; D. S. Day ; Y. Dong ; A. C. Dose ; X. Duan ; C. B. Epstein ; S. Ercan ; E. A. Feingold ; F. Ferrari ; J. M. Garrigues ; N. Gehlenborg ; P. J. Good ; P. Haseley ; D. He ; M. Herrmann ; M. M. Hoffman ; T. E. Jeffers ; P. V. Kharchenko ; P. Kolasinska-Zwierz ; C. V. Kotwaliwale ; N. Kumar ; S. A. Langley ; E. N. Larschan ; I. Latorre ; M. W. Libbrecht ; X. Lin ; R. Park ; M. J. Pazin ; H. N. Pham ; A. Plachetka ; B. Qin ; Y. B. Schwartz ; N. Shoresh ; P. Stempor ; A. Vielle ; C. Wang ; C. M. Whittle ; H. Xue ; R. E. Kingston ; J. H. Kim ; B. E. Bernstein ; A. F. Dernburg ; V. Pirrotta ; M. I. Kuroda ; W. S. Noble ; T. D. Tullius ; M. Kellis ; D. M. MacAlpine ; S. Strome ; S. C. Elgin ; X. S. Liu ; J. D. Lieb ; J. Ahringer ; G. H. Karpen ; P. J. Park
Nature Publishing Group (NPG)
Published 2014Staff ViewPublication Date: 2014-08-29Publisher: Nature Publishing Group (NPG)Print ISSN: 0028-0836Electronic ISSN: 1476-4687Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsKeywords: Animals ; Caenorhabditis elegans/*cytology/*genetics ; Cell Line ; Centromere/genetics/metabolism ; Chromatin/chemistry/*genetics/*metabolism ; Chromatin Assembly and Disassembly/genetics ; DNA Replication/genetics ; Drosophila melanogaster/*cytology/*genetics ; Enhancer Elements, Genetic/genetics ; Epigenesis, Genetic ; Heterochromatin/chemistry/genetics/metabolism ; Histones/chemistry/metabolism ; Humans ; Molecular Sequence Annotation ; Nuclear Lamina/metabolism ; Nucleosomes/chemistry/genetics/metabolism ; Promoter Regions, Genetic/genetics ; Species SpecificityPublished by: -
3Articles: DFG German National Licensesde Leeuw, N. H. ; Parker, S. C.
College Park, Md. : American Institute of Physics (AIP)
Published 2000Staff ViewISSN: 1089-7690Source: AIP Digital ArchiveTopics: PhysicsChemistry and PharmacologyNotes: We introduce a potential model for MgCO3 and CdCO3 which reproduces experimental structural parameters and solution energies. We employed atomistic simulation techniques to model the absorption and segregation of magnesium and cadmium ions to the low-index surfaces of calcite. Both magnesium and cadmium ions absorb at the surfaces from solution. The absorption energies are surface dependent, due to distinct relaxations of the different surfaces, and ion dependent with the smaller sized magnesium ion showing larger relaxations. The absorption energies are larger for magnesium than for cadmium, mainly due to the closer coordination of the water molecules to the magnesium substituted surfaces. The cadmium ions segregate to the bulk crystal more easily than the magnesium ions which prefer to remain at the surface. However, segregation energies for both cations in second and further layers of some surfaces are positive, indicating that once a calcium carbonate layer has overgrown the substituted surface layer, segregation to the bulk is energetically possible. © 2000 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
4Articles: DFG German National LicensesStaff View
ISSN: 1365-2230Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: MedicineNotes: We report a classical case of scleredema which pursued a chronic progressive course and was associated with poorly controlled diabetes mellitus.Type of Medium: Electronic ResourceURL: -
5Articles: DFG German National LicensesParker, S. C. ; Lawrence, P. J. ; Freeman, C. M. ; Levine, S. M. ; Newsam, J. M.
Springer
Published 1992Staff ViewISSN: 1572-879XKeywords: Computer simulation ; SEM ; catalyst modelling ; Cr2O3 ; crystal morphology ; surface segregation ; chromiaSource: Springer Online Journal Archives 1860-2000Topics: Chemistry and PharmacologyNotes: Abstract The shapes of small crystals grown under equilibrium conditions are governed by the stabilities of their exposed faces. Computer simulation methods can be used to calculate surface energies and hence crystallite morphologies, illustrated by results for Cr2O3. Such calculations can include the effects of surface impurity segregation. Comparison of the resulting calculated crystal morphologies with those directly observed in the SEM thus provides a direct link between atomistic simulation and experiment.Type of Medium: Electronic ResourceURL: -
6Articles: DFG German National LicensesStaff View
ISSN: 1572-879XKeywords: methanol synthesis ; copper catalysts ; Cu-ZnO catalysts ; water-gas shift ; reverse water-gas shiftSource: Springer Online Journal Archives 1860-2000Topics: Chemistry and PharmacologyNotes: Abstract The kinetics of simultaneous methanol synthesis and reverse water-gas shift from CO2/H2 mixtures have been measured at low conversions over a clean polycrystalline Cu foil at pressures of 5 bar. An absolute rate of 1.2 × 10−3 methanol molecules produced per second per Cu surface atom was observed at 510 K, with an activation energy of 77 ± 10 kJ/mol. The rate of CO production was 0.12 molecules per second per Cu surface atom at this temperature, with an activation energy of 135 ± 5 kJ/mol. The rates, normalized to the metallic Cu surface area, are equal to those measured over real, high-area Cu/ZnO catalysts. The surface after reaction was examined by XPS and TPD. It was covered by almost a full monolayer of adsorbed formate, but no other species like carbon or oxygen in measurable amounts. These results prove that a highly active site for methanol synthesis on real Cu/ZnO catalysts is metallic Cu, and suggest that the rate-determining step in methanol synthesis is one of the several steps in the further hydrogenation of adsorbed formate to methanol.Type of Medium: Electronic ResourceURL: -
7Articles: DFG German National LicensesStaff View
ISSN: 1476-4687Source: Nature Archives 1869 - 2009Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsNotes: [Auszug] CATLOW AND PARKER REPLY-The comments of Walker on our simulation study of pyroxenoids raise two issues. First, what is the 'accuracy' of the calculated lattice energies; second, what further tests of our method are possible. Regarding the question of accuracy we stress that the methods used by our ...Type of Medium: Electronic ResourceURL: -
8Articles: DFG German National LicensesCatlow, C. R. A. ; Thomas, J. M. ; Parker, S. C. ; Jefferson, D. A.
[s.l.] : Nature Publishing Group
Published 1982Staff ViewISSN: 1476-4687Source: Nature Archives 1869 - 2009Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsNotes: [Auszug] Chain silicates, both naturally-occurring and synthetic, exhibit ‘backbone repeat’ patterns of corner-linked SiO4 tetrahedra. The extent to which these repeats may be interpreted or predicted, as a function of the associated cation M2+ (in the general ...Type of Medium: Electronic ResourceURL: -
9Articles: DFG German National LicensesStaff View
ISSN: 1432-2021Source: Springer Online Journal Archives 1860-2000Topics: Chemistry and PharmacologyGeosciencesPhysicsNotes: Abstract The elastic constants of a crystal under stress, defined as the second derivative of the crystal free energy with respect to strain, require a correction related to the static pressure at non-zero pressures. The corrections required for the elastic constants calculated by the free energy minimisation code PARAPOCS are described and tested by comparison with the elastic constants calculated numerically by applying small stresses in the appropriate orientations to simulated crystals of fluorite, forsterite, α-quartz and albite. The corrected elastic constants are then used to investigate the extrapolation of the bulk and shear moduli (and hence also the seismic wave velocities V p and V s) of β-spinel and forsterite to upper mantle pressures. A Murnaghan equation, thirdorder Eulerian finite strain equation, second order polynomial equation and a logistic equation were all fitted to the simulated bulk and shear moduli between 0 and 3 GPa pressure. The parameters derived for these equations are used to extrapolate the bulk and shear moduli to 14 GPa and the results are compared to the simulated high pressure moduli. Over this pressure range, the second order polynomial provides the best extrapolation of the bulk modulus, but the use of the logistic equation results in the best extrapolation of the shear modulus.Type of Medium: Electronic ResourceURL: -
10Articles: DFG German National LicensesStaff View
ISSN: 1432-2021Source: Springer Online Journal Archives 1860-2000Topics: Chemistry and PharmacologyGeosciencesPhysicsNotes: Abstract A computational method, based on the quasiharmonic approximation, has been computer-coded to calculate the temperature dependence of elastic constants and structural features of crystals. The model is applied to calcite, CaCO3; an interatomic potential based on a C-O Morse function and Ca-O and O-O Borntype interactions, including a shell model for O, has been used. Equilibrations in the range 300–800 K reproduce the experimental unit-cell edges and bond lengths within 1%. The simulated thermal expansion coefficients are 22.3 (//c) and 2.6 (⊥ c), against 25.5 and-3.7×10−6K−1 experimental values, respectively. The thermal coefficients of elastic constants tend to be underestimated; for the bulk modulus, -2.3 against-3.7×10−4K−1 is obtained.Type of Medium: Electronic ResourceURL: -
11Articles: DFG German National LicensesStaff View
ISSN: 1432-2021Source: Springer Online Journal Archives 1860-2000Topics: Chemistry and PharmacologyGeosciencesPhysicsNotes: Abstract The aim of this paper is to demonstrate that atomistic simulations can be used to evaluate the structure of mineral surfaces and to provide reliable data for forsterite surfaces up to a plane index of 2 using the code METADISE. The methods used to calculate the surface structure and energy which have more commonly been used to study ceramics are briefly explained as is a comparison with experimental data, most notable the crystal morphology. The predicted morphologies show that all the methods (Donnay-Harker, Attachment energies and equilibrium) show most of the surfaces that are expressed in observed crystals. The equilibrium morphology calculated from the relaxed surface energies is the only method which expresses the {201} surfaces and the {101} surfaces, which appear only upon relaxation. The more stable surfaces are shown to be those which have the highest surface density and more closely resemble close packed structures with highly coordinated surface ions and silicon as far from the surface as possible. The most stable surfaces the {100} which has alternating layers of MgO and SiO2 terminating with an MgO layer. The structure is similar to the MgO {100} surfaces and has a similar energy (1.28 Jm−2 compared to 1.20). The second most stable are the {201} which have a stepped surface topology, but is also compact with a relaxed surface energy of 1.56 Jm−2. The results indicate that atomistic simulation is well suited to the prediction of surface structure and morphology although care must be taken in choosing potentials which model the structure and elastic properties accurately.Type of Medium: Electronic ResourceURL: -
12Articles: DFG German National LicensesStaff View
ISSN: 1432-2021Keywords: Key words Diffusion ; Grain boundary ; Impurities ; PressureSource: Springer Online Journal Archives 1860-2000Topics: Chemistry and PharmacologyGeosciencesPhysicsNotes: Abstract We present the results of atomistic simulations to calculate the effect of impurities on vacancy migration at the {4 1 0} tilt grain boundary of MgO. We show that impurities within the mantle could significantly modify vacancy migration within the mantle due to segregation to grain boundaries. This segregation increases with increasing impurity size and with increasing pressure. The impurities have little effect on vacancy migration at 0 GPa but at higher pressures the impurities alter the activation energies such that the vacancies prefer to migrate towards them. This suggests that at mantle conditions the vacancies will be pinned both by the compression of the boundary and also the impurities, slowing diffusion.Type of Medium: Electronic ResourceURL: -
13Articles: DFG German National LicensesStaff View
ISSN: 1432-2021Keywords: Key words Forsterite ; Atomistic simulation ; Adsorption of water ; Surface reactivity ; MorphologySource: Springer Online Journal Archives 1860-2000Topics: Chemistry and PharmacologyGeosciencesPhysicsNotes: Abstract We describe the application of atomistic simulation techniques to investigate the effect of associative and dissociative adsorption of water on the structures and stabilities of the low-index surfaces of forsterite. All surfaces are amenable to associative adsorption of water, while dissociative adsorption is energetically favourable on all but the non-dipolar {1 0 0} surface. Often, otherwise unstable (dipolar) surfaces are stabilised to a large extent by hydration, e.g. the dipolar {0 1 0} surface. However, on thermodynamic grounds we do not expect associatively adsorbed water to dissociate on all surfaces, as the energies released for dissociative adsorption of water on the non-dipolar {0 1 0} and {1 0 0} surfaces are less than those released for associative adsorption. As such, there is no energetic incentive for the associatively adsorbed water molecules to dissociate. The stabilities of the two terminations of the {0 1 0} surface, the main cleavage plane of forsterite, are reversed when hydroxylated, indicating that some dissolution of the magnesium ions may occur upon hydration, which is shown to be an exothermic process for both surface terminations. The equilibrium morphology was calculated as a way of assessing the change in surface energies. The experimental morphology of forsterite is adequately reproduced, suggesting that the relative stabilities of the surfaces, both unhydrated and hydroxylated, are calculated correctly.Type of Medium: Electronic ResourceURL: -
14Articles: DFG German National LicensesDavis, A. ; Leigh, C. R. A. ; Hampton, R. N. ; Saunders, G. A. ; Parker, S. C.
Springer
Published 1988Staff ViewISSN: 1573-4811Source: Springer Online Journal Archives 1860-2000Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision MechanicsType of Medium: Electronic ResourceURL: