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Rymer AM, Mauk BH, Hill TW, Paranicas C, André N, Sittler EC, Mitchell DG, Smith HT, Johnson RE, Coates AJ, Young DT, Bolton SJ, Thomsen MF, Dougherty MK. Electron sources in Saturn's magnetosphere. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006ja012017] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Sittler EC, Johnson RE, Smith HT, Richardson JD, Jurac S, Moore M, Cooper JF, Mauk BH, Michael M, Paranicas C, Armstrong TP, Tsurutani B. Energetic nitrogen ions within the inner magnetosphere of Saturn. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2004ja010509] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Thompson RH, Johnson RE. Blood pyruvate in vitamin B(1) deficiency. Biochem J 2006; 29:694-700. [PMID: 16745714 PMCID: PMC1266536 DOI: 10.1042/bj0290694] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Johnson RE, Meiklejohn AP, Passmore R, Thompson RH. A note on the level of carbonyl compounds in human blood. Biochem J 2006; 29:2506-9. [PMID: 16745935 PMCID: PMC1266791 DOI: 10.1042/bj0292506] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Johnson RE. The isolation of pyruvic acid from the blood of vitamin B(1)-deficient pigeons. Biochem J 2006; 30:31-2. [PMID: 16745989 PMCID: PMC1263355 DOI: 10.1042/bj0300031] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Jones RM, Johnson RE, Rothemich SF, Woolf SH. Colorectal Cancer Screening Adherence in a Diverse Patient Population. Am J Epidemiol 2006. [DOI: 10.1093/aje/163.suppl_11.s107-d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Kwok RK, Fears T, Kleinerman RA, Freedman DM, Alexander BH, Kampa D, Johnson RE, Linet MS. Assessing Activities Associated with Time Spent Outdoors in an Occupational Cohort of Radiologic Technologists. Am J Epidemiol 2006. [DOI: 10.1093/aje/163.suppl_11.s91-d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Cohen ME, Consolazio F, Johnson RE. BLOOD LACTATE RESPONSE DURING MODERATE EXERCISE IN NEUROCIRCULATORY ASTHENIA, ANXIETY NEUROSIS, OR EFFORT SYNDROME. J Clin Invest 2006; 26:339-42. [PMID: 16695423 PMCID: PMC435675 DOI: 10.1172/jci101814] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Sargent F, Robinson P, Johnson RE, Castiglione M. F(1) AND F(2) OF NAJJAR AND HOLT IN THE URINE OF NORMAL YOUNG MEN. J Clin Invest 2006; 23:714-9. [PMID: 16695154 PMCID: PMC435392 DOI: 10.1172/jci101543] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Berman SM, Johnson RE. Commentary. Br J Vener Dis 2006. [DOI: 10.1136/sti.2006.017905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Tokar RL, Johnson RE, Hill TW, Pontius DH, Kurth WS, Crary FJ, Young DT, Thomsen MF, Reisenfeld DB, Coates AJ, Lewis GR, Sittler EC, Gurnett DA. The Interaction of the Atmosphere of Enceladus with Saturn's Plasma. Science 2006; 311:1409-12. [PMID: 16527967 DOI: 10.1126/science.1121061] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
During the 14 July 2005 encounter of Cassini with Enceladus, the Cassini Plasma Spectrometer measured strong deflections in the corotating ion flow, commencing at least 27 Enceladus radii (27 x 252.1 kilometers) from Enceladus. The Cassini Radio and Plasma Wave Science instrument inferred little plasma density increase near Enceladus. These data are consistent with ion formation via charge exchange and pickup by Saturn's magnetic field. The charge exchange occurs between neutrals in the Enceladus atmosphere and corotating ions in Saturn's inner magnetosphere. Pickup ions are observed near Enceladus, and a total mass loading rate of about 100 kilograms per second (3 x 10(27) H(2)O molecules per second) is inferred.
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Johnson RE, Cooper PD, Quickenden TI, Grieves GA, Orlando TM. Production of oxygen by electronically induced dissociations in ice. J Chem Phys 2005; 123:184715. [PMID: 16292929 DOI: 10.1063/1.2107447] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A solid-state chemical model is given for the production of O2 by electronic excitation of ice, a process that occurs on icy bodies in the outer solar system. Based on a review of the relevant available laboratory data, we propose that a trapped oxygen atom-water complex is the principal precursor for the formation of molecular oxygen in low-temperature ice at low fluences. Oxygen formation then occurs through direct excitation of this complex or by its reaction with a freshly produced, nonthermal O from an another excitation event. We describe a model for the latter process that includes competition with precursor destruction and the effect of sample structure. This allows us to put the ultraviolet photon, low-energy electron, and fast-ion experiments on a common footing for the first time. The formation of the trapped oxygen atom precursor is favored by the preferential loss of molecular hydrogen and is quenched by reactions with mobile H. The presence of impurity scavengers can limit the trapping of O, leading to the formation of oxygen-rich molecules in ice. Rate equations that include these reactions are given and integrated to obtain an analytic approximation for describing the experimental results on the production and loss of molecular oxygen from ice samples. In the proposed model, the loss rate varies, roughly, inversely with solid-state defect density at low temperatures, leading to a yield that increases with increasing temperature as observed. Cross sections obtained from fits of the model to laboratory data are evaluated in light of the proposed solid-state chemistry.
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Sittler EC, Hartle RE, Viñas AF, Johnson RE, Smith HT, Mueller-Wodarg I. Titan interaction with Saturn's magnetosphere: Voyager 1 results revisited. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2004ja010759] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Aggarwal AK, Nair DT, Trincao J, Uljon SN, Johnson RE, Escalante CR, Edwards TA, Prakash S, Prakash L. Eukaryotic translesion synthesis DNA polymerases: structure and function. Acta Crystallogr A 2005. [DOI: 10.1107/s0108767305097503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Young DT, Berthelier JJ, Blanc M, Burch JL, Bolton S, Coates AJ, Crary FJ, Goldstein R, Grande M, Hill TW, Johnson RE, Baragiola RA, Kelha V, McComas DJ, Mursula K, Sittler EC, Svenes KR, Szegö K, Tanskanen P, Thomsen MF, Bakshi S, Barraclough BL, Bebesi Z, Delapp D, Dunlop MW, Gosling JT, Furman JD, Gilbert LK, Glenn D, Holmlund C, Illiano JM, Lewis GR, Linder DR, Maurice S, McAndrews HJ, Narheim BT, Pallier E, Reisenfeld D, Rymer AM, Smith HT, Tokar RL, Vilppola J, Zinsmeyer C. Composition and Dynamics of Plasma in Saturn's Magnetosphere. Science 2005; 307:1262-6. [PMID: 15731443 DOI: 10.1126/science.1106151] [Citation(s) in RCA: 257] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
During Cassini's initial orbit, we observed a dynamic magnetosphere composed primarily of a complex mixture of water-derived atomic and molecular ions. We have identified four distinct regions characterized by differences in both bulk plasma properties and ion composition. Protons are the dominant species outside about 9 RS (where RS is the radial distance from the center of Saturn), whereas inside, the plasma consists primarily of a corotating comet-like mix of water-derived ions with approximately 3% N+. Over the A and B rings, we found an ionosphere in which O2+ and O+ are dominant, which suggests the possible existence of a layer of O2 gas similar to the atmospheres of Europa and Ganymede.
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Funsten HO, Ritzau SM, Harper RW, Borovsky JE, Johnson RE. Energy loss by keV ions in silicon. PHYSICAL REVIEW LETTERS 2004; 92:213201. [PMID: 15245278 DOI: 10.1103/physrevlett.92.213201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2003] [Indexed: 05/24/2023]
Abstract
Using silicon photodiodes with an ultrathin passivation layer, the average total energy lost to silicon target electrons (electronic stopping) by incident low energy ions and the recoil target atoms they generate is directly measured. We find that the total electronic energy deposition and the ratio of the total nuclear to electronic stopping powers for the incident ions and their recoils each follow a simple, universal representation, thus enabling systematic prediction of ion-induced effects in silicon. We also observe a velocity threshold at 0.05 a.u. for the onset of electronic stopping.
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Johnson RE, Harrowe DJ, McFarland BH, Bavry JL. Comparing the use of short-acting and long-acting calcium channel blockers in an HMO. Pharmacoepidemiol Drug Saf 2004; 7:155-66. [PMID: 15073993 DOI: 10.1002/(sici)1099-1557(199805/06)7:3<155::aid-pds344>3.0.co;2-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
One of the questions surrounding the controversy over the risks of MI among hypertensives taking calcium channel blockers (CCBs) is the dosage form, and whether the short-acting form may be more likely than the long-acting to increase the risk of MI. This preliminary study compared HMO members receiving the two dosage forms by sociodemographic and clinical characteristics, and by utilization (hospital, office visits, emergency room, outside of HMO services) prior to and during CCB use. The sampling frame was members with one or more dispensings for a CCB 1990 through 1994. Incident users were those who received one or more CCB dispensings and no cardiovascular disease-related drugs the year prior to their first dispensing of a CCB. CCB users were those who had at least 90 days of continuous CCB use. Short-acting outnumbered long-acting users by eight to one. Few incident users of long-acting CCBs were found. Among incident users, diagnoses and comorbidities were similar. In general, short-acting users appeared to have less risk of exposure to heart-related medications, but similar risks of exposure to non-heart-related drugs and to utilization of the various services during the year prior to first use. The odds of being exposed to heart-related medications and non-heart related medications and use of services during periods of use of CCBs were similar in general, but where differences were observed, the odds of being exposed were less among short-acting users. Users of the two dosage forms in this setting prior to reports questioning the safety of short-acting CCBs were different quantitatively and qualitatively making a retrospective comparative study difficult, perhaps not possible, due to substantial selection bias among users. Further patient selection bias has also undoubtedly occurred subsequent to the reports. The final answer to the relative safety and effectiveness of the different dosage forms of calcium channel blockers is likely to have come from randomized clinical trials.
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Prakash S, Johnson RE, Washington MT, Haracska L, Kondratick CM, Prakash L. Role of yeast and human DNA polymerase eta in error-free replication of damaged DNA. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2003; 65:51-9. [PMID: 12760020 DOI: 10.1101/sqb.2000.65.51] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Ranganathan S, Johnson RE. Molecular dynamics study of a bilayer electron gas: single particle properties. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 67:041201. [PMID: 12786347 DOI: 10.1103/physreve.67.041201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2002] [Indexed: 05/24/2023]
Abstract
The single-particle dynamical properties of a strongly coupled, classical, symmetric electronic bilayer system have been investigated by molecular dynamics simulation. Results for the velocity correlation function, the single-particle scattering function, and their respective Fourier transforms have been calculated, and their behavior, as a function of the interlayer separation d, has been analyzed. The single-particle scattering function in particular, shows dramatic effects when the bilayer attains a staggered square lattice structure. This occurs when the interlayer separation is around 0.8a (a is the Wigner-Seitz radius), where our previous study showed a marked decrease in the diffusion coefficient.
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Johnson RE, Quickenden TI, Cooper PD, McKinley AJ, Freeman CG. The production of oxidants in Europa's surface. ASTROBIOLOGY 2003; 3:823-850. [PMID: 14987485 DOI: 10.1089/153110703322736123] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The oxidants produced by radiolysis and photolysis in the icy surface of Europa may be necessary to sustain carbon-based biochemistry in Europa's putative subsurface ocean. Because the subduction of oxidants to the ocean presents considerable thermodynamic challenges, we examine the formation of oxygen and related species in Europa's surface ice with the goal of characterizing the chemical state of the irradiated material. Relevant spectral observations of Europa and the laboratory data on the production of oxygen and related species are first summarized. Since the laboratory data are incomplete, we examine the rate equations for formation of oxygen and its chemical precursors by radiolysis and photolysis. Measurements and simple rate equations are suggested that can be used to characterize the production of oxidants in Europa's surface material and the chemical environment produced by radiolysis. Possible precursor molecules and the role of radical trapping are examined. The possibility of oxygen reactions on grain surfaces in Europa's regolith is discussed, and the earlier estimates of the supply of O(2) to the atmosphere are increased.
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Johnson RE, Papaefthymiou GC, Frankel RB, Holm RH. Effects of secondary bonding interactions on the iron-sulfur cubane-type [Fe4S4]2+ core of ferredoxin site analogs: [Fe4S4(SC6H4-o-OH)4]2-, a distorted cubane-type cluster with one five-coordinate iron atom. J Am Chem Soc 2002. [DOI: 10.1021/ja00363a013] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Kivel J, Albers FC, Olsen DA, Johnson RE. SURFACE AREAS BY ADSORPTION OF A QUATERNARY AMMONIUM HALIDE FROM AQUEOUS SOLUTION. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100800a016] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Liu HF, Liu RS, Liew KY, Johnson RE, Lunsford JH. Partial oxidation of methane by nitrous oxide over molybdenum on silica. J Am Chem Soc 2002. [DOI: 10.1021/ja00327a009] [Citation(s) in RCA: 300] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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