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1,230 results on '"Johnston, Karen A."'

51. Pacemaker Implantation After Mitral Valve Surgery With Atrial Fibrillation Ablation

Author

Miller, Marissa A., Taddei-Peters, Wendy C., Buxton, Dennis, Connolly, Amy, Geller, Nancy L., Gordon, David, Jeffries, Neal O., Lee, Albert, Moy, Claudia S., Gombos, Ilana Kogan, Ralph, Jennifer, Weisel, Richard, Gardner, Timothy J., O’Gara, Patrick T., Rose, Eric A., Gelijns, Annetine C., Parides, Michael K., Ascheim, Deborah D., Moskowitz, Alan J., Bagiella, Emilia, Moquete, Ellen, Chang, Helena, Chase, Melissa, Dobrev, Edlira, Goldfarb, Seth, Gupta, Lopa, Kirkwood, Katherine, Levitan, Ron, O’Sullivan, Karen, Overbey, Jessica, Santos, Milerva, Weglinski, Michael, Williams, Paula, Wood, Carrie, Ye, Xia, Mack, Michael, Adame, Tracine, Settele, Natalie, Adams, Jenny, Ryan, William, Smith, Robert L., Grayburn, Paul, Chen, Frederick Y., Nohria, Anju, Cohn, Lawrence, Shekar, Prem, Aranki, Sary, Couper, Gregory, Davidson, Michael, Bolman, R. Morton, III, Burgess, Anne, Conboy, Debra, Blackwell, Ray, Kerzner, Roger, Banbury, Michael, Squire, Andrea M., Gillinov, A. Marc, Blackstone, Eugene H., Lytle, Bruce, Mihaljevic, Tomislav, Lackner, Pamela, Berroteran, Leoma, Dolney, Diana, Fleming, Suzanne, Palumbo, Roberta, Whitman, Christine, Sankovic, Kathy, Sweeney, Denise Kosty, Pattakos, Gregory, Argenziano, Michael, Williams, Mathew, Goldsmith, Lyn, Smith, Craig R., Naka, Yoshifumi, Stewart, Allan, Schwartz, Allan, Bell, Daniel, Van Patten, Danielle, Sreekanth, Sowmya, Smith, Peter K., Alexander, John H., Milano, Carmelo A., Glower, Donald D., Mathew, Joseph P., Harrison, J. Kevin, Welsh, Stacey, Ferguson, T. Bruce, Kypson, Alan P., Rodriguez, Evelio, Harris, Malissa, Akers, Brenda, O'Neal, Allison, Puskas, John D., Thourani, Vinod H., Guyton, Robert, Baer, Jefferson, Baio, Kim, Neill, Alexis A., Voisine, Pierre, Senechal, Mario, Dagenais, François, O’Connor, Kim, Dussault, Gladys, Ballivian, Tatiana, Keilani, Suzanne, Michler, Robert E., D'Alessandro, David A., DeRose, Joseph J., Jr., Goldstein, Daniel J., Bello, Ricardo, Jakobleff, William, Garcia, Mario, Taub, Cynthia, Spevack, Daniel, Swayze, Roger, Sookraj, Nadia, Perrault, Louis P., Basmadjian, Arsène-Joseph, Bouchard, Denis, Carrier, Michel, Cartier, Raymond, Pellerin, Michel, Tanguay, Jean François, El-Hamamsy, Ismael, Denault, André, Lacharité, Jonathan, Robichaud, Sophie, Adams, David H., Varghese, Robin, Mandel-Portnoy, Yael, Horvath, Keith A., Corcoran, Philip C., Siegenthaler, Michael P., Murphy, Mandy, Iraola, Margaret, Greenberg, Ann, Sai-Sudhakar, Chittoor, Hasan, Ayseha, McDavid, Asia, Kinn, Bradley, Mullen, John C., Choy, Jonathan, Meyer, Steven, Kuurstra, Emily, Gammie, James S., DeFilippi, Christopher R., Gaetani, Dino T., Young, Cindi A., Beach, Dana, Collins, Julia, Bolling, Steven F., Pagani, Francis D., Bloem, Cathie, Acker, Michael A., Woo, Y. Joseph, Mayer, Mary Lou, Bavaria, Joseph E., Szeto, Wilson Y., Margulies, Kenneth, Keane, Martin, Glassberg, Helene, Jagasia, Dinesh, Kirkpatrick, James, Kron, Irving L., Ailawadi, Gorav, Johnston, Karen, Dent, John M., Kern, John, Keim, Jessica, Burks, Sandra, Gahring, Kim, Mangi, Abeel, Akar, Joseph, Yuh, David, Wilson, Lynn, Bull, David A., Desvigne-Nickens, Patrice, Dixon, Dennis O., Haigney, Mark, Holubkov, Richard, Jacobs, Alice, Miller, Frank, Murkin, John M., Spertus, John, Wechsler, Andrew S., Sellke, Frank, McDonald, Cheryl L., Byington, Robert, Dickert, Neal, Ikonomidis, John S., Williams, David O., Yancy, Clyde W., Canty, John M., Jr., Fang, James C., Giannetti, Nadia, Richenbacher, Wayne, Rao, Vivek, Furie, Karen L., Miller, Rachel, Pinney, Sean, Roberts, William C., Walsh, Mary N., Hung, Judy, Zeng, Xin, Couderc, Jean-Philippe, Balda, Dan, Bowen, Wayne, Wilson, Mauri, Schering, Anne, Mancini, Donna M., Chang, Helena L., Mack, Michael J., Yerokun, Babatunde A., Atluri, Pavan, Sledz, Nancy M., Tremblay, Hugo, Ferket, Bart S., and Iribarne, Alexander

Published
2019
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53. Adsorption structures of phenol on the Si(001)-(2 \times 1) surface calculated using density functional theory

Author

Johnston, Karen, Gulans, Andris, Verho, Tuukka, and Puska, Martti J.

Subjects
Physics - Computational Physics, Condensed Matter - Materials Science
Abstract

Several dissociated and two non-dissociated adsorption structures of the phenol molecule on the Si(001)-(2 \times 1) surface are studied using density functional theory with various exchange and correlation functionals. The relaxed structures and adsorption energies are obtained and it is found that the dissociated structures are energetically more favourable than the non-dissociated structures. However, the ground state energies alone do not determine which structure is obtained experimentally. To elucidate the situation core level shift spectra for Si 2p and C 1s states are simulated and compared with experimentally measured spectra. Several transition barriers were calculated in order to determine which adsorption structures are kinetically accessible. Based on these results we conclude that the molecule undergoes the dissociation of two hydrogen atoms on adsorption., Comment: 11 pages, 6 figures

Published
2010
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56. Active representation and identity taxation: unintended outcome of representative labour?

Author

Johnston, Karen and Yarrow, Emily

Subjects
CHARTER schools, TAXATION, UNIVERSITIES & colleges, GENDER inequality
Abstract

Drawing on the theory of representative bureaucracy, which shows that minority bureaucrats will actively represent the interests of minorities from the same socio-demographic group, we argue that institutions could use active representation for institutional performative goals through identity taxation resulting in an unintended outcome of representative labour. We contribute a novel conceptual model of representative labour, enhancing the understanding of the individual–organizational interface, through research involving 35 interviews with academics and professionals, who have a role in addressing gender inequality in British and Irish higher educational institutions through an equality charter award scheme, namely Athena SWAN. [ABSTRACT FROM AUTHOR]

Published
2024
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57. Representative bureaucracy and organizational attractiveness: An experimental study of symbolic representation of the US and UK police.

Author

Johnston, Karen, Alberti, Federica, and Kravariti, Foteini

Subjects
BUREAUCRACY, POLICE, REPUTATION, PUBLIC spaces
Abstract

Drawing upon representative bureaucracy theory, this study investigates the relationship between passive and symbolic representation by examining the extent to which a more passively representative public organization would be attractive as an employer. The study involved a randomized survey experiment of members of the public in the US and UK. Overall, and contrary to the theory of representative bureaucracy, results show that women found a male‐dominated police department more attractive. The explanation for the results of the study may lie in bureaucratic reputation as a boundary condition of symbolic representation. [ABSTRACT FROM AUTHOR]

Published
2024
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58. Seven Strategies to Integrate Equity within Translational Research in Neurology.

Author

Lizarraga, Karlo J., Gyang, Tirisham, Benson, Richard T., Birbeck, Gretchen L., Johnston, Karen C., Royal, Walter, Sacco, Ralph L., Segal, Benjamin, Vickrey, Barbara G., Griggs, Robert C., and Holloway, Robert G.

Subjects
TRANSLATIONAL research, NEUROLOGICAL research, MEDICAL technology, BEST practices
Abstract

The rapidly accelerating translation of biomedical advances is leading to revolutionary therapies that are often inaccessible to historically marginalized populations. We identified and synthesized recent guidelines and statements to propose 7 strategies to integrate equity within translational research in neurology: (1) learn history; (2) learn about upstream forces; (3) diversify and liberate; (4) change narratives and adopt best communication practices; (5) study social drivers of health and lived experiences; (6) leverage health technologies; and (7) build, sustain, and lead culturally humble teams. We propose that equity should be a major goal of translational research, equally important as safety and efficacy. ANN NEUROL 2024;95:432–441 [ABSTRACT FROM AUTHOR]

Published
2024
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64. The Lives Lost to Inequities

Author

Woolf, Steven H., primary, Chapman, Derek A., additional, Lee, Jong Hyung, additional, Johnston, Karen C., additional, Benson, Richard T., additional, Trevathan, Edwin, additional, Smith, Wally R., additional, and Gaskin, Darrell J., additional

Published
2023
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65. Mission and role modelling in producing a fit‐for‐purpose rural health workforce: perspectives from an international community of practice

Author

Larkins, Sarah L, primary, Cristobal, Fortunato, additional, Hogenbirk, John, additional, Tandinco, Filedito, additional, Othman, Abu‐Bakr, additional, Mbokazi, Jabu, additional, Van Roy, Kaatje, additional, Upadhyay, Shambhu, additional, Johnston, Karen, additional, and Neusy, Andre‐Jacques, additional

Published
2023
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66. Computational study of (111) epitaxially strained ferroelectric perovskites BaTiO3 and PbTiO3

Author

Oja, Riku, Johnston, Karen, Frantti, Johannes, and Nieminen, Risto M.

Subjects
Condensed Matter - Materials Science
Abstract

The phase transition behaviour of PbTiO3 and BaTiO3 under (111) epitaxial strain is investigated using density-functional theory calculations. From tensile strains of +0.015 to compressive strains of -0.015, PbTiO3 undergoes phase transitions from C2 through two Cm phases and then to R3m. The total polarisation is found to be almost independent of strain. For the same range of strains BaTiO3 undergoes phase transitions from a single Cm phase, through R3m and then to R-3m. In this case the application of compressive strain inhibits and then completely suppresses the polarisation on transition to the non-polar R-3m phase., Comment: 6 pages, 5 figures, REVTeX 4; text, references and corrections added, to be published in Phys. Rev. B

Published
2008
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67. Influence of van der Waals forces on the adsorption structure of benzene on silicon

Author

Johnston, Karen, Kleis, Jesper, Lundqvist, Bengt I., and Nieminen, Risto M.

Subjects
Physics - Computational Physics, Physics - Chemical Physics
Abstract

Two different adsorption configurations of benzene on the Si(001)-(2x1) surface, the tight-bridge and butterfly structures, were studied using density functional theory. Several exchange and correlation functionals were used, including the recently developed vdW-DF functional, which accounts for the effect of van der Waals forces. In contrast to the PBE, revPBE and other GGA functionals, the vdW-DF functional finds that, for most coverages, the adsorption energy of the butterfly structure is greater than that of the tight-bridge structure., Comment: 4 pages, 1 figure, to be published in Physical Review B, 77 (2008): revPBE and PBE data in Tables I, II and III has been corrected, PW91 data has been added to Tables II and III

Published
2008
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68. Polarization Enhancement in Short Period Superlattices via Interfacial Intermixing

Author

Cooper, Valentino R., Johnston, Karen, and Rabe, Karin M.

Subjects
Condensed Matter - Materials Science
Abstract

The effect of intermixing at the interface of short period PbTiO$_3$/SrTiO$_3$ superlattices is studied using first-principles density functional theory. The results indicate that interfacial intermixing significantly enhances the polarization within the superlattice. This enhancement is directly related to the off-centering of Pb and Sr cations and can be explained through a discussion of interacting dipoles. This picture should be general for a wide range of multicomponent superlattices and may have important consequences for the design of ferroelectric devices., Comment: 4 pages, 6 figures

Published
2007
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69. Polymer adhesion: first-principles calculations of the adsorption of organic molecules onto Si surfaces

Author

Johnston, Karen and Nieminen, Risto M.

Subjects
Condensed Matter - Materials Science
Abstract

The structures and energetics of organic molecules adsorbed onto clean and H-passivated Si(001)-(2$\times$1) surfaces have been calculated using density functional theory. For benzene adsorbed on the clean Si surface the tight-bridge structure was found to be stable and the butterfly structure metastable. Both carbonic acid H$_2$CO$_3$ and propane C$_3$H$_8$ dissociate on contact with the surface. Passivation of the Si surface with H-atoms has a dramatic effect on the surface properties. The passivated surface is very inert and the binding energy of all the molecules is very weak., Comment: 8 pages, 13 figures

Published
2007
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70. Final Report on the Evaluation of the National Science Foundation's Instructional Materials Development Program.

Author

National Science Foundation, Arlington, VA. Directorate for Education and Human Resources., WestEd, San Francisco, CA., Tushnet, Naida C., Millsap, Mary Ann, Abdullah-Welsh, Noraini, Brigham, Nancy, Cooley, Elizabeth, Elliott, Jeanne, Johnston, Karen, Martinez, Alina, Nierenberg, Marla, and Rosenblum, Sheila

Abstract

This document presents the final report on the evaluation of the Instructional Materials Development (IMD) program of the National Science Foundation (NSF) and focuses on issues related to the development, dissemination, adoption, implementation, and impact of new instructional materials. The IMD program evaluates products at each step, from product development to classroom use. Instruments are included for evaluating elementary and secondary school science and mathematics materials for classroom use. (Contains 15 references.) (YDS)

Published
2000

72. First-principles study of symmetry lowering in relaxed BaTiO3/SrTiO3 superlattices

Author

Johnston, Karen, Huang, Xiangyang, Neaton, Jeffrey B., and Rabe, Karin M.

Subjects
Condensed Matter - Materials Science
Abstract

The crystal structure and local spontaneous polarization of (BaTiO3)m/(SrTiO3)n superlattices is calculated using a first-principles density functional theory method. The in-plane lattice constant is 1% larger than the SrTiO3 substrate to imitate the relaxed superlattice structure and the symmetry is lowered to monoclinic space group Cm which allows polarization to develop along the [110] and [001] directions. The polarization component in the [110] direction is found to develop only in the SrTiO3 layers and falls to zero in the BaTiO3 layers, whereas the polarization in the [001] direction is approximately uniform throughout the superlattice. These findings are consistent with recent experimental data and first-principles results for epitaxially strained BT and ST., Comment: 4 pages, 2 figures

Published
2004
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73. National Institutes of Health StrokeNet During the Time of COVID-19 and Beyond

Author

Broderick, Joseph P., Elm, Jordan J., Janis, L. Scott, Zhao, Wenle, Moy, Claudia S., Dillon, Catherine R., Chimowitz, Marc I., Sacco, Ralph L., Cramer, Steven C., Wolf, Steven L., Johnston, Karen C., Saver, Jeffrey L., Marshall, Randolph S., Brown, Devin, Wintermark, Max, Elkind, Mitchell S.V., Kamel, Hooman, Tirschwell, David L., Longstreth, W.T., Chervin, Ronald D., Adeoye, Opeolu M., Barreto, Andrew D., Grotta, James C., Ramey, Sharon L., Lo, Warren D., Feng, Wuwei, Schlaug, Gottfried, Sheth, Kevin N., Selim, Magdy, Naidech, Andrew M., Lansberg, Maarten G., Lazar, Ronald M., Albers, Gregory W., Griffin, Jessica S., Sirline, Logan P., Frasure, Jamey, Wright, Clinton B., and Khatri, Pooja

Published
2020
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75. A complementary study of perovskites : combining diffraction, solid-state NMR and first principles DFT calculations

Author

Johnston, Karen Elizabeth, Lightfoot, Philip, and Ashbrook, Sharon

Subjects
546.3, Oxides--Synthesis, Oxides--Analysis, Neutrons--Diffraction, Magnetic resonance imaging, Density functionals
Abstract

Perovskites, ABX₃, and their associated solid-solutions are a particularly important and attractive area of research within materials chemistry. Owing to their structural and compositional flexibility and potential physical properties they are one of the largest classes of materials currently under investigation. This thesis is concerned with the synthesis and structural characterisation of several perovskite-based materials using a combined approach of high-resolution synchrotron X-ray and neutron powder diffraction (NPD), solid-state Nuclear Magnetic Resonance (NMR) and first-principles Density Functional Theory (DFT) calculations. Initial investigations concentrated on room temperature NaNbO₃, a perovskite widely debated in the literatue. Published crystallographic data indicate NaNbO₃ possesses two crystallographically distinct Na sites in space group Pbcm. Whilst some of our materials appear in agreement with this (notably a commercially purchased sample) many of our laboratory-synthesised samples of NaNbO₃ routinely comprise of two phases, which we show to be the antiferroelectric Pbcm and polar P2₁ma polymorphs. Several different synthetic methods were utilised during this investigation and the quantity of each phase present was found to vary as a function of preparative method. ²³Na, ⁹³Nb and ¹⁷O DFT calculations were used in conjunction with experiment to aid in spectral analysis, assignment and interpretation. In addition, ab initio random structure searching (AIRSS) was utilised in an attempt to predict the most stable phases of NaNbO₃. This proved to be both successful and highly informative. A series of NaNbO₃-related solid-solutions, namely K[subscript(x)]Na[subscript(1-x)]NbO₃ (KNN), Li[subscript(x)]Na[subscript(1-x)]NbO₃ (LNN) and Na[subscript(1-x)]Sr[subscript(x/2)]□[subscript(x/2)]NbO₃ (SNN) have also been synthesised and characterised. The substitution of K⁺ , Li⁺ and Sr²⁺ cations onto the A site appears to produce the same polar P2₁ma phase initially identified in the room temperature NaNbO₃ investigation. The abrupt change in cation size in the KNN and LNN series, and the introduction of vacancies in the SNN series, is thought to result in a structural distortion which, in turn, causes the formation of the P2₁ma phase. A low temperature synchrotron X-ray powder diffraction study (12 < T < 295 K) was completed for a sample of NaNbO₁ composed of the P2₁ma polymorph (~90%) and a small quantity of the Pbcm phase (~10%). A region of phase coexistence was identified between the P2₁ma, R3c and Pbcm phases over a relatively large temperature range. Full conversion of the P2₁ma phase to the low temperature R3c phase was not possible and, consistently, the P2₁ma phase was the most abundant phase present. Factors such as structural, strain, crystallite size and morphology are thought to be crucial in determining the exact phases of NaNbO₃ produced, both at low and room temperature. The solid-solution La[subscript(1-x)]Y[subscript(x)]ScO₃ was also investigated. Compositions x = 0, 0.2, 0.4, 0.6, 0.8 and 1 were successfully synthesised and characterised. Refined high-resolution NPD data indicates that an orthorhombic structure, in space group Pbnm, was retained throughout the solid-solution. Using ⁴⁵Sc and ⁸⁹Y MAS NMR each sample was found to exhibit disorder, believed to result from both a distribution of quadrupole and chemical shifts. NMR parameters were calculated for several model Sc and Y compounds using DFT methods to determine the feasibility and accuracy of ⁴⁵Sc and ⁸⁹Y DFT calculations. These proved successful and subsequent calculations were completed for the end members LaScO₃ and YScO₃. DFT calculations were also utilised to gain insight into the disorder exhibited in the La[subscript(1-x)]Y[subscript(x)]ScO₃ solid-solution.

Published
2010

78. Twenty-Year Disparity Trends in United States Stroke Death Rate by Age, Race/Ethnicity, Geography, and Socioeconomic Status

Author

de Havenon, Adam, primary, Zhou, Lily W, additional, Johnston, Karen C, additional, Dangayach, Neha S, additional, Ney, John, additional, Yaghi, Shadi, additional, Sharma, Richa, additional, Abbasi, Mehdi, additional, Delic, Alen, additional, Majersik, Jennifer Juhl, additional, Anadani, Mohammad, additional, Tirschwell, David L., additional, and Sheth, Kevin Navin, additional

Published
2023
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82. Democratising data to address health system inequities in Australia

Author

Topp, Stephanie M, primary, Thompson, Fintan, additional, Johnston, Karen, additional, Smith, Deborah, additional, Edelman, Alexandra, additional, Whittaker, Maxine, additional, Rouen, Christopher, additional, Moodley, Nishila, additional, McDonald, Malcolm, additional, Barker, Ruth, additional, and Larkins, Sarah, additional

Published
2023
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84. Governance and public policies: Support for women entrepreneurs in France and England?

Author

Johnston, Karen, Danho, Ekoua J, Yarrow, Emily, Cameron, Robert, Dann, Zoe, Ekinsmyth, Carol, Busoi, Georgiana, and Doyle, Amy

Subjects
BUSINESSWOMEN, GOVERNMENT policy, BUREAUCRACY
Abstract

We extend the current literature on barriers to women's entrepreneurship by providing the perspectives of women entrepreneurs' lived experience of governance and public policies designed to support entrepreneurship, in France and England. The research draws on primary data comprising interviews with 75 French and English women entrepreneurs as well as secondary data. The research suggests that in France the system of governance is relatively more supportive, whereas in England there are less favourable views of bureaucracy and the conditionality of financial policy instruments, which in turn create unintended outcomes. We extend current understandings of gendered public policies and governance. Points for practitioners: The public policy and governance context in France offers relatively more support for women entrepreneurs than in England. There is a potential for policy learning in how to support women entrepreneurs. Financial policy instruments such as social welfare payments may affect women entrepreneurship. Bureaucracy creates time and opportunity costs for women entrepreneurs, which have a gendered impact if they are single parents and have dependents. [ABSTRACT FROM AUTHOR]

Published
2023
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94. Assessment of GAFF and OPLS Force Fields for Urea: Crystal and Aqueous Solution Properties

Author

Anker, Samira, McKechnie, David, Mulheran, Paul, Sefcik, Jan, and Johnston, Karen

Abstract

Molecular simulations such as Monte Carlo, molecular dynamics, and metadynamics have been used to provide insight into crystallization phenomena, including nucleation and crystal growth. However, these simulations depend on the force field used, which models the atomic and molecular interactions, to adequately reproduce relevant material properties for the phases involved. Two widely used force fields, the General AMBER Force Field (GAFF) and the Optimized Potential for Liquid Simulations (OPLS), including several variants, have previously been used for studying urea crystallization. In this work, we investigated how well four different versions of the GAFF force field and five different versions of the OPLS force field reproduced known urea crystal and aqueous solution properties. Two force fields were found to have the best overall performance: a specific urea charge-optimized GAFF force field and the original all-atom OPLS force field. It is recommended that a suitable testing protocol involving both solution and solid properties, such as that used in this work, is adopted for the validation of force fields used for simulations of crystallization phenomena.

Published
2024
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