Search

Your search keyword '"Fahy, S."' showing total 307 results
Start Over Author "Fahy, S."
307 results on '"Fahy, S."'

1. Photo-induced plasmon-phonon coupling in PbTe

Author

Jiang, M. P., Trigo, M., Fahy, S., Hauber, A., Murray, É. D., Savić, I, Bray, C., Clark, J. N., Henighan, T., Kozina, M., Chollet, M., Glownia, J. M., Hoffmann, M. C., Zhu, D., Delaire, O., May, A. F., Sales, B. C., Lindenberg, A. M., Zalden, P., Sato, T., Merlin, R., and Reis, D. A.

Subjects
Condensed Matter - Materials Science
Abstract

We report the observation of photo-induced plasmon-phonon coupled modes in the group IV-VI semiconductor PbTe using Fourier-transform inelastic X-ray scattering at the Linac Coherent Light Source (LCLS). We measure the near-zone-center dispersion of the heavily screened longitudinal optical (LO) phonon branch as extracted from differential changes in x-ray diffuse scattering intensity following above band gap photoexcitation., Comment: 5 pages, 2 figures

Published
2021

2. Evolution of non-thermal phonon and electron populations in photo-excited germanium on picosecond timescales

Author

Murphy-Armando, F., Murray, É. D., Savić, I., Trigo, M., Reis, D., and Fahy, S.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We investigate from first-principles theory and experiment the generation of phonons on picosecond timescales and the relaxation of carriers in multiple conduction band valleys of photo-excited Ge by inter-valley electron-phonon scattering. We provide a full description of the phonon and electron relaxation dynamics without adjustable parameters. Simulations of the time-evolution of phonon populations, based on first-principles band structure and electron-phonon and phonon-phonon matrix elements, are compared with data from time-resolved x-ray diffuse scattering experiments, performed at the LCLS x-ray free-electron laser facility, which measures the diffuse scattering intensity following photo-excitation by a 50 fs near-infrared optical pulse. Comparing calculations and measurements show that the intensity of the non-thermal x-ray diffuse scattering signal, that is observed to grow substantially near the L-point of the Brillouin zone over 3-5 ps, is due to phonons generated by scattering of carriers between the $\Delta$ and L valleys. Non-thermal phonon populations throughout the Brillouin zone are observed and simulated from first principles without adjustable parameters for times up to 10 ps. With inclusion of phonon decay through 3-phonon processes, the simulations also account for other non-thermal features observed in the x-ray diffuse scattering intensity, which are due to anharmonic phonon-phonon scattering of the phonons initially generated by electron-phonon scattering., Comment: 12 pages, 14 figures

Published
2019

3. Photoinduced suppression of the ferroelectric instability in PbTe

Author

Jiang, M. P., Trigo, M., Fahy, S., Murray, É. D., Savić, I., Bray, C., Clark, J., Henighan, T., Kozina, M., Chollet, M., Glownia, J. M., Hoffmann, M., Zhu, D., Delaire, O., May, A. F., Sales, B. C., Lindenberg, A. M., Zalden, P., Sato, T., Merlin, R., and Reis, D. A.

Subjects
Condensed Matter - Materials Science
Abstract

The interactions between electrons and phonons drive a large array of technologically relevant material properties including ferroelectricity, thermoelectricity, and phase-change behaviour. In the case of many group IV-VI, V, and related materials, these interactions are strong and the materials exist near electronic and structural phase transitions. Their close proximity to phase instability produces a fragile balance among the various properties. The prototypical example is PbTe whose incipient ferroelectric behaviour has been associated with large phonon anharmonicity and thermoelectricity. Experimental measurements on PbTe reveal anomalous lattice dynamics, especially in the soft transverse optical phonon branch. This has been interpreted in terms of both giant anharmonicity and local symmetry breaking due to off-centering of the Pb ions. The observed anomalies have prompted renewed theoretical and computational interest, which has in turn revived focus on the extent that electron-phonon interactions drive lattice instabilities in PbTe and related materials. Here, we use Fourier-transform inelastic x-ray scattering (FT-IXS) to show that photo-injection of free carriers stabilizes the paraelectric state. With support from constrained density functional theory (CDFT) calculations, we find that photoexcitation weakens the long-range forces along the cubic direction tied to resonant bonding and incipient ferroelectricity. This demonstrates the importance of electronic states near the band edges in determining the equilibrium structure., Comment: 9 page, 3 figures

Published
2015

4. How to distinguish squeezed and coherent phonons in femtosecond x-ray diffuse scattering

Author

Henighan, T., Trigo, M., Chollet, M., Clark, J. N., Fahy, S., Glownia, J. M., Jiang, M. P., Kozina, M., Liu, H., Song, S., Zhu, D., and Reis, D. A.

Subjects
Condensed Matter - Materials Science
Abstract

Impulsive optical excitation can generate both coherent and squeezed phonons. The expectation value of the phonon displacement $$ oscillates at the mode frequency for the coherent state but remains zero for a pure squeezed state. In contrast, both show oscillations in $<|u_q|^2>$ at twice the mode frequency. Therefore it can be difficult to distinguish them in a second-order measurement of the displacements, such as in first-order x-ray diffuse scattering. Here we demonstrate a simple method to distinguish squeezed from coherent atomic motion by measurement of the diffuse scattering following double impulsive excitation. We find that femtosecond optical excitation generates squeezed phonons spanning the Brillouin zone in Ge, GaAs and InSb. Our results confirm the mechanism suggested in [Nature Physics 9, 790 (2013)]., Comment: 5 pages, 3 figures

Published
2015
Full Text
View/download PDF

7. Direct measurement of time-dependent density-density correlations in a solid through the acoustic analog of the dynamical Casimir effect

Author

Trigo, M., Fuchs, M., Chen, J., Jiang, M. P., Kozina, M. E., Ndabashimiye, G., Cammarata, M., Chien, G., Fahy, S., Fritz, D. M., Gaffney, K., Ghimire, S., Higginbotham, A., Johnson, S. L., Larsson, J., Lemke, H., Lindenberg, A. M., Quirin, F., Sokolowski-Tinten, K., Uher, C., Wark, J. S., Zhu, D., and Reis, D. A.

Subjects
Condensed Matter - Materials Science
Abstract

The macroscopic characteristics of a solid, such as its thermal, optical or transport properties are determined by the available microscopic states above its lowest energy level. These slightly higher quantum states are described by elementary excitations and dictate the response of the system under external stimuli. The spectrum of these excitations, obtained typically from inelastic neutron and x-ray scattering, is the spatial and temporal Fourier transform of the density-density correlation function of the system, which dictates how a perturbation propagates in space and time. As frequency-domain measurements do not generally contain phase information, time-domain measurements of these fluctuations could yield a more direct method for investigating the excitations of solids and their interactions both in equilibrium and far-from equilibrium. Here we show that the diffuse scattering of femtosecond x-ray pulses produced by a free electron laser (FEL) can directly measure these density-density correlations due to lattice vibrations in the time domain. We obtain spectroscopic information of the lattice excitations with unprecedented momentum- and frequency- resolution, without resolving the energy of the outgoing photon. Correlations are created via an acoustic analog of the dynamical Casimir effect, where a femtosecond laser pulse slightly quenches the phonon frequencies, producing pairs of squeezed phonons at momenta +q and -q. These pairs of phonons manifest as macroscopic, time-dependent coherences in the displacement correlations that are then probed directly by x-ray scattering. Since the time-dependent correlations are preferentially created in regions of strong electron-phonon coupling, the time-resolved approach is natural as a spectroscopic tool of low energy collective excitations in solids, and their microscopic interactions, both in linear response and beyond.

Published
2013

8. Free-carrier relaxation and lattice heating in photoexcited bismuth thin films

Author

Sheu, Y. M., Chien, Y. J., Uher, C., Fahy, S., and Reis, D. A.

Subjects
Condensed Matter - Materials Science
Abstract

We report ultrafast surface pump and interface probe experiments on photoexcited carrier transport across single crystal bismuth films on sapphire. The film thickness is sufficient to separate carrier dynamics from lattice heating and strain, allowing us to investigate the time-scales of momentum relaxation, heat transfer to the lattice and electron-hole recombination. The measured electron-hole ($e-h$) recombination time is 12--26 ps and ambipolar diffusivity is 18--40 cm$^{2}$/s for carrier excitation up to $\sim 10^{19} \text{cm}^{-3}$. By comparing the heating of the front and back sides of the film, we put lower limits on the rate of heat transfer to the lattice, and by observing the decay of the plasma at the back of the film, we estimate the timescale of electron-hole recombination. We interpret each of these timescales within a common framework of electron-phonon scattering and find qualitative agreement between the various relaxation times observed. We find that the carrier density is not determined by the $e-h$ plasma temperature after a few picoseconds. The diffusion and recombination become nonlinear with initial excitation $\gtrsim 10^{20} \text{cm}^{-3}$.

Published
2012
Full Text
View/download PDF

9. Simulations of Time-Resolved X-Ray Diffraction in Laue Geometry

Author

Lings, B., DeCamp, M. F., Reis, D. A., Fahy, S., and Wark, J. S.

Subjects
Condensed Matter - Materials Science
Abstract

A method of computer simulation of Time-Resolved X-ray Diffraction (TRXD) in asymmetric Laue (transmission) geometry with an arbitrary propagating strain perpendicular to the crystal surface is presented. We present two case studies for possible strain generation by short-pulse laser irradiation: (i) a thermoelastic-like analytic model; (ii) a numerical model including effects of electron-hole diffusion, Auger recombination, deformation potential and thermal diffusion. A comparison with recent experimental results is also presented., Comment: 9 pages, 11 figures

Published
2005
Full Text
View/download PDF

10. Supersonic strain front driven by a dense electron-hole plasma

Author

DeCamp, M. F., Reis, D. A., Cavalieri, A., Bucksbaum, P. H., Clarke, R., Merlin, R., Dufresne, E. M., Arms, D. A., Lindenberg, A. M., MacPhee, A. G., Chang, Z., Lings, B., Wark, J. S., and Fahy, S.

Subjects
Condensed Matter - Materials Science
Abstract

We study coherent strain in (001) Ge generated by an ultrafast laser-initiated high density electron-hole plasma. The resultant coherent pulse is probed by time-resolved x-ray diffraction through changes in the anomalous transmission. The acoustic pulse front is driven by ambipolar diffusion of the electron-hole plasma and propagates into the crystal at supersonic speeds. Simulations of the strain including electron-phonon coupling, modified by carrier diffusion and Auger recombination, are in good agreement with the observed dynamics., Comment: 4 pages, 6 figures

Published
2002
Full Text
View/download PDF

11. Calculations of the A_1 phonon frequency in photoexcited Tellurium

Author

Tangney, P. and Fahy, S.

Subjects
Condensed Matter - Materials Science
Abstract

Calculations of the A_1 phonon frequency in photoexcited tellurium are presented. The phonon frequency as a function of photoexcited carrier density and phonon amplitude is determined. Recent pump probe experiments are interpreted in the light of these calculatons. It is proposed that, in conjunction with measurements of the phonon period in ultra-fast pump-probe reflectivity experiments, the calculated frequency shifts can be used to infer the evolution of the density of photoexcited carriers on a sub-picosecond time-scale., Comment: 15 pages Latex, 3 postscript figures

Published
1998
Full Text
View/download PDF

15. Ultrafast Bond Softening in Bismuth: Mapping a Solid's Interatomic Potential with X-Rays

Author

Fritz, D. M., Reis, D. A., Adams, B., Akre, R. A., Arthur, J., Blome, C., Bucksbaum, P. H., Cavalieri, A. L., Engemann, S., Fahy, S., Falcone, R. W., Fuoss, P. H., Gaffney, K. J., George, M. J., Hajdu, J., Hertlein, M. P., Hillyard, P. B., Hoegen, M. Horn-von, Kammler, M., Kaspar, J., Kienberger, R., Krejcik, P., Lee, S. H., Lindenberg, A. M., McFarland, B., Meyer, D., Montagne, T., Murray, É. D., Nelson, A. J., Nicoul, M., Pahl, R., Rudati, J., Schlarb, H., Siddons, D. P., Sokolowski-Tinten, K., Tschentscher, Th., von der Linde, D., and Hastings, J. B.

Published
2007
Full Text
View/download PDF

16. Observation of photo-induced plasmon–phonon coupling in PbTe via ultrafast x-ray scattering

Author

Jiang, M. P., primary, Fahy, S., additional, Hauber, A., additional, Murray, É. D., additional, Savić, I., additional, Bray, C., additional, Clark, J. N., additional, Henighan, T., additional, Kozina, M., additional, Lindenberg, A. M., additional, Zalden, P., additional, Chollet, M., additional, Glownia, J. M., additional, Hoffmann, M. C., additional, Sato, T., additional, Zhu, D., additional, Delaire, O., additional, May, A. F., additional, Sales, B. C., additional, Merlin, R., additional, Trigo, M., additional, and Reis, D. A., additional

Published
2022
Full Text
View/download PDF

21. National scientific medical meeting 1997 abstracts

Author

Willison, H. J., Lastovica, A. J., Prendergast, M. M., Moran, A. P., Walsh, C., Flitcroft, I., Eustace, P., McMahon, C., Smith, J., Smith, O. P., Lakshmandass, G., Taylor, M. R. H., Holland, C. V., Cox, D., Good, B., Kearns, G. M., Gaffney, P., Shark, K., Frauenshuh, M., Ortmann, W., Messner, R., King, R., Rich, S., Behrens, T., Mahmud, N., Molloy, A., McPartlin, J., Scott, J. M., Weir, D. G., Walsh, K. M., Thorburn, D., Mills, P., Morris, A. J., Good, T., Cameron, S., McCruden, E. A. B., Bennett, M. W., O’Connell, J., Brady, C., Roche, D., Collins, J. K., Shanahan, F., O’Sullivant, G. C., Henry, M., Koston, S., McMahon, K., MacNee, W., FitzGerald, M. X., O’Connor, C. M., McGonagle, D., Gibbon, W., O’Connor, P., Emery, P., Murphy, M., Watson, R., Casey, E., Naidu, E., Murphy, M., Watson, R., Barnes, L., McCann, S., Murphy, M., Watson, R., Barnes, L., Sweeney, E., Barrett, E. J., Graham, H., Cunningham, R. T., Johnston, C. F., Curry, W. J., Buchanan, K. D., Courtney, C. H., McAllister, A. S., McCance, D. R., Hadden, D. R., Bell, P. M., Leslie, H., Sheridan, B., Atkinson, A. B., Kilbane, M. T., Smith, D. F., Murray, M. J., Shering, S. G., McDermott, E. W. M., O’Higgins, N. J., Smyth, P. P. A., McEneny, J., Trimble, E. R., Young, I. S., Sharpe, P., Mercer, C., McMaster, D., Young, I. S., Evans, A. E., Young, I. S., Cundick, J., Hasselwander, O., McMaster, D., McGeough, J., Savage, D., Maxwell, A. P., Evans, A. E., Kee, F., Larkin, C. J., Watson, R. G. P., Johnston, C., Ardill, J. E. S., Buchanan, K. D., McNamara, D. A., Walsh, T. N., Bouchier-Hayes, D. J., Madden, C., Timon, C., Gardiner, N., Lawler, M., O’Riordan, J., Duggan, C., McCann, S. R., Gowing, H., Braakman, E., Lawler, M., Byrne, C., Martens, A. C. M., Hagenbeek, A., McCann, S. R., Kinsella, N., Cusack, S., Lawler, M., Baker, H., White, B., Smith, O. P., Lawler, M., Gardiner, N., Molloy, K., Gowing, H., Wogan, A., McCann, S. R., McElwaine, S., Lawler, M., Hollywood, D., McCann, S. R., Mcmahon, C., Merry, C., Ryan, M., Smith, O., Mulcahy, F. M., Murphy, C., Briones, J., Gardiner, N., McCann, S. R., Lawler, M., White, B., Lawler, M., Cusack, S., Kinsella, N., Smith, O. P., Lavin, P., McCaffrey, M., Gillen, P., White, B., Smith, O. P., Thompson, L., Lalloz, M., Layton, M., Barnes, L., Corish, C., Kennedy, N. P., Flood, P., Mulligan, S., McNamara, E., Kennedy, N. P., Flood, P., Mathias, P. M., Ball, E., Duiculescu, D., Calistru, P., O’Gorman, N., Kennedy, N. P., Abuzakouk, M., Feighery, C., Brannigan, M., Pender, S., Keeling, F., Varghese, J., Lee, M., Colreavy, M., Gaffney, R., Hone, S., Herzig, M., Walsh, M., Dolan, C., Wogan, A., Lawler, M., McCann, S. R., Hollywood, D., Donovan, D., Harmey, J., Bouchier-Hayes, D. J., Haverty, A., Wang, J. H., Harmey, J. H., Redmond, H. P., Bouchier-Hayes, D. J., McGreal, G., Shering, S. G., Moriarty, M. J., Shortt, A., Kilbane, M. T., Smith, D. F., McDermott, E. W. M., O’Higgins, N. J., Smyth, P. P. A., McNamara, D. A., Harmey, J., Wang, J. H., Donovan, D., Walsh, T. N., Bouchier-Hayes, D. J., Kay, E., Pidgeon, G., Harmey, J., McNamara, D. A., Bouchier-Hayes, D. J., Dunne, P., Lambkin, H., Russell, J. M., O’Neill, A. J., Dunne, B. M., O’Donovan, M., Lawler, M., Gaffney, E. F., Gillan, J. E., Cotter, T. G., Horan, J., Jones, D., Biswas, S. K., Mulkerrin, E. C., Brady, H., O’Donnell, J., Neary, J., Healy, E., Watson, A., Keogh, B., Ryan, M., Cassidy, C., Ward, S., Stokes, E., Keoghan, F., Barrett, A., O’Connell, P., Ryall, N., O’Connell, P. A., Jenkinson, A., O’Brien, T., O’Connell, P. G., Harrison, R., Barrett, T., Bailey, D. M. D., Butler, A., Barton, D. E., Byrne, C., McElwaine, S., McCann, S. R., Lawler, M., Cusack, S., Lawler, M., White, B., Smith, O. P., Daly, G., Gill, M., Heron, S., Hawi, Z., Fitzgerald, M., Hawi, Z., Mynett-Johnson, L., Shiels, D., Kendler, K., McKeon, P., Gill, M., Straub, R., Walsh, D., Ryan, F., Barton, D. E., McCabe, D., Murphy, R., Segurado, R., Mulcahy, T., Larson, B., Comerford, C., O’Connell, R., O’Mahony, E., Gill, M., Donnelly, J., Minahan, F., O’Neill, D., Farrell, Z., O’Neill, D., Jones, D., Horan, J., Glynn, C., Biswas, S. K., Mulkerrin, E., Brady, H., Lennox, S. E., Murphy, A., Rea, I. M., McNulty, H., McMeel, C., O’Neill, D., McEvoy, H., Freaney, R., McKenna, M. J., Crowe, M., Keating, D., Colreavy, M., Hone, S., Norman, G., Widda, S., Viani, L., Galvin, Nolan, C. M., Hardiman, O., Hardiman, O., Brett, F., Droogan, O., Gallagher, P., Harmey, M., King, M., Murphy, J., Perryrnan, R., Sukumaran, S., Walsh, J., Farrell, M. A., Hughes, G., Cunningham, C., Walsh, J. B., Coakley, D., O’Neill, D., Hurson, M., Flood, P., McMonagle, P., Hardiman, O., Ryan, F., O’Sullivan, S., Merry, C., Dodd, P., Redmond, J., Mulcahy, F. M., Browne, R., Keating, S., O’Connor, J., Cassidy, B. P., Smyth, R., Sheppard, N. P., Cullivan, R., Crown, J., Walsh, N., Denihan, A., Bruce, I., Radic, A., Coakley, D., Lawlor, B. A., Bridges, P. K., O’Doherty, M., Farrington, A., O’Doherty, M., Farragher, B., Fahy, S., Kelly, R., Carey, T., Owens, J., Gallagher, O., Sloan, D., McDonough, C., Casey, P., Horgan, A., Elneihum, A., O’Neill, C., McMonagle, T., Quinn, J., Meagher, D., Murphy, P., Kinsella, A., Mullaney, J., Waddington, J. L., Rooney, S., Rooney, S., Bamford, L., Sloan, D., O’Connor, J. J., Franklin, R., O’Brien, K., Fitzpatrick, G., Laffey, J. G., Boylan, J. F., Laffey, J., Coleman, M., Boylan, J., Laffey, J. G., McShane, A. J., Boylan, J. F., Loughrey, J. P. R., Gardiner, J., McGinley, J., Leonard, I., Carey, M., Neligan, P., O’Rourke, J., Cunningham, A., Fennessy, F., Kelly, C., Bouchier-Hayes, D., Fennessy, F., Wang, J. H., Kelly, C., Bouchier-Hayes, D., Fennessy, F., Wang, J. H., Kelly, C., Bouchier-Hayes, D. J., Kellett, J., Laffey, J., Murphy, D., Regan, J., O’Keeffe, D., Mahmud, A., Hemeryck, L., Feely, J., Mahmud, A., Hemeryck, L., Hall, M., Feely, J., Menown, I. B. A., Mathew, T. P., Nesbitt, G. S., Syme, M., Young, I. S., Adgey, A. A. J., Menown, I. B. A., Turtle, F., Allen, J., Anderson, J., Adgey, A. A. J., O’Hanlon, R., Codd, M. B., Walkin, S., McCann, H. A., Sugrue, D. D., Rasheed, A. M., Chen, G., Kelly, C., Bouchier-Hayes, D. J., Leahy, A., Rasheed, A. M., Kay, E., Jina, S., Bouchier-Hayes, D. J., Leahy, A., McDowell, I., Rasheed, A. M., Wang, J. H., Wo, Q., Kelly, C., Bouchier-Hayes, D. J., Leahy, A., Shuhaibar, M. N., McGovern, E., Turtle, F., Menown, I. B. A., Manoharan, G., Kirkpatrick, R., Campbell, N. P. S., Walkin, S., Codd, M. B., O’Hanlon, R., McCarthy, C., McCann, H. A., Sugrue, D. D., Wen, Y., Killalea, S., Hall, M., Hemeryck, L., Feely, J., Fahy, C. J., Griffith, A., McGinley, J., McCabe, D., Fraser, A., Casey, E., Ryan, T., Murphy, R., Browne, M., Fenton, J., Hughes, J., Timon, C. I., Fenton, J., Curran, A., Smyth, D., Viani, L., Walsh, M., Hughes, J. P., Fenton, J., Lee, P., Kelly, A., Timon, C. I., Hughes, J. P., Fenton, J., Shine, N., Blayney, A., McShane, D. P., Timon, C. I., Hussey, J., Howlett, M., Langton, A., McEvoy, A., Slevin, J., Fitzpatrick, C., Turner, M. J., Enright, F., Goggin, N., Costigan, C., Duff, D., Osizlok, P., Wood, F., Watson, R., Fitzsimons, R. B., Flanagan, N., Enright, F., Barnes, L., Watson, R., Molloy, E., Griffin, E., Deasy, P. F., Sheridan, M., White, M. J., Moore, R., Gray, A., Hill, J., Glasgow, J. F. T., Middleton, B., Slattery, D., Donoghue, V., McMahon, A., Murphy, J., Slattery, D., McCarthy, A., Oslislok, P., Duff, D., Colreavy, M., Keogh, I., Hone, S., Walsh, M., Henry, M., Koston, S., McMahon, K., MacNee, W., FitzGerald, M. X., O’Connor, C. M., Russell, K. J., Henry, M., Fitzgerald, M. X., O’Connor, C. M., Kavanagh, P. V., McNamara, S. M., Feely, J., Barry, M., O’Brien, J. E., McCormick, P., Molony, C., Doyle, R. M., Walsh, J. B., Coakley, D., Codd, M. B., O’Connell, P. R., Dowey, L. C., McGlynn, H., Thurnham, D. I., Elborn, S. J., Flynn, L., Carton, J., Byrne, B., O’Farrelly, C., Kelehan, P., O’Herlihy, C., O’Hara, A. M., Moran, A. P., Orren, A., Fernie, B. A., Merry, C., Clarke, S., Courtney, G., de Gascun, C., Mulcahy, F. M., Merry, C., Ryan, M., Barry, M., Mulcahy, F. M., Merry, C., Ryan, M., Barry, M., Mulcahy, F. M., Byrne, M., Moylett, E., Murphy, H., Butler, K., Nourse, C., Thaker, H., Barry, C., Russell, J., Sheehan, G., Boyle, B., Hone, R., Conboy, B., Butler, C., Moris, D., Cormican, M., Flynn, J., McCormack, O., Corbally, N., Murray, A., Kirrane, S., O’Keane, C., Hone, R., Lynch, S. M., Cryan, B., Whyte, D., Morris, D., Butler, C., Cormican, M., Flynn, J., Corbett-Feeney, G., Murray, A., Corbally, N., Hone, R., Mackle, T., Colreavy, M., Perkins, J., Saidlear, C., Young, A., Eustace, P., Wrigley, M., Clifford, J., Waddington, J. L., Tighe, O., Croke, D. T., Drago, J., Sibley, D. R., Feely, J., Kelly, A., Carvalho, M., Hennessy, M., Kelly, M., Feely, J., Hughes, C., Hanlon, M., Feely, J., Sabra, K., Keane, T., Egan, D., Ryan, M., Maerry, C., Ryan, M., Barry, M., Mulcahy, F. M., Maerry, C., Ryan, M., Barry, M., Mulcahy, F. M., Sharma, S. C., Williams, D., Kelly, A., Carvalho, M., Feely, J., Williams, D., Kelly, A., Carvalho, M., Feely, J., Codd, M. B., Mahon, N. G., McCann, H. A., Sugrue, D. D., Sayers, G. M., Johnson, Z., McNamara, S. M., Kavanagh, P. V., and Feely, J.

Published
1998
Full Text
View/download PDF

23. The Irish paediatrics association and section of paediatrics, royal academy of medicine in Ireland: Proceedings of joint meeting held May 15th & 16th, 1992 in Great Northern Hotel, Bundoran, Co. Donegal

Author

Miyakita, H., Puri, P., Zia S., Kearney P. J., Lambert, I., Browne, P., O’Brien, N., Carson, J., Temperley, I. J., Jackson, F., White, M., Beckett, M., O’Regan, M., Matthews, T., Jalees, S., McDonagh, B., McMenamin, J., Gumaa, S., Connolly, K., Egan Mitchell, B., McNicholl, B., Loftus, B. G., Kinlen, D. M., Hoey, H. M. C. V., Burke-Gaffney, A., Reen, D. J., Hill, R., Hensey, O. J., McKay, M., Hutchinson, T., Fallon, M., Kelly, M., Gorman, W., Clarke, T., Griffin, E., Matthews, T., Murphy, J., O’Brien, N., Sheridan, M., Philip, M., McCann, S., Connolly, B., O’Brien, N., King, M., Gorman, W., Hensey, O., Donoghue, V., Fahy, S., Nicholson, A., O’Keefe, M., Surana, R., O’Nuallain, E. M., Monaghan, H., Mulrane, S., Taylor, M., Tempany, E., Bourke, B., Lyons, D., McCarthy, J. F., Neligan, M. C., Wood, A. E., Murphy, A. W., Power, R., Kinlen, D., Johnson, Z., Quinn, F., Brady, R. M., Arvind, A., Healy, R., Staines, A., Bodansky, H. J., Stephenson, C., Haigh, D., Cartwright, R. A., Puri, I., O’Hagan, M., Zbaeda, M. M., Bagyaraj, A., Wall, O., O’Connell, U., Bate, T., Losty, P., Lynch, M., Guiney, E. J., Hassan, J., Gormally, S., Drumm, B., Abraham, G., Costigan, C., Fogarty, J., Moloney, A. C., Ninan, G., and Fitzgerald, R. J.

Published
1993
Full Text
View/download PDF

34. First principles calculation of electron-phonon and alloy scattering in strained SiGe.

Author

Murphy-Armando, F. and Fahy, S.

Subjects
*ELECTRON-phonon interactions, *SILICON, *GERMANIUM, *ALLOYS, *SCATTERING (Physics), *STRAIN theory (Chemistry), *COMPLEMENTARY metal oxide semiconductors, *THERMAL conductivity
Abstract

First-principles electronic structure methods are used to predict the mobility of n-type carrier scattering in strained SiGe. We consider the effects of strain on the electron-phonon deformation potentials and the alloy scattering parameters. We calculate the electron-phonon matrix elements and fit them up to second order in strain. We find, as expected, that the main effect of strain on mobility comes from the breaking of the degeneracy of the six Δ and L valleys, and the choice of transport direction. The non-linear effects on the electron-phonon coupling of the Δ valley due to shear strain are found to reduce the mobility of Si-like SiGe by 50% per % strain. We find increases in mobility between 2 and 11 times that of unstrained SiGe for certain fixed Ge compositions, which should enhance the thermoelectric figure of merit in the same order, and could be important for piezoresistive applications. [ABSTRACT FROM AUTHOR]

Published
2011
Full Text
View/download PDF

35. Giant enhancement of n-type carrier mobility in highly strained germanium nanostructures.

Author

Murphy-Armando, F. and Fahy, S.

Subjects
*NANOSTRUCTURES, *GERMANIUM, *SCATTERING (Physics), *LATTICE dynamics, *PHONONS, *ELECTRIC conductivity
Abstract

First-principles electronic structure methods are used to predict the rate of n-type carrier scattering due to phonons in highly-strained Ge. We show that strains achievable in nanoscale structures, where Ge becomes a direct bandgap semiconductor, cause the phonon-limited mobility to be enhanced by hundreds of times that of unstrained Ge, and over a thousand times that of Si. This makes highly tensile strained Ge a most promising material for the construction of channels in CMOS devices, as well as for Si-based photonic applications. Biaxial (001) strain achieves mobility enhancements of 100 to 1000 with strains over 2%. Low temperature mobility can be increased by even larger factors. Second order terms in the deformation potential of the Γ valley are found to be important in this mobility enhancement. Although they are modified by shifts in the conduction band valleys, which are caused by carrier quantum confinement, these mobility enhancements persist in strained nanostructures down to sizes of 20 nm. [ABSTRACT FROM AUTHOR]

Published
2011
Full Text
View/download PDF

36. 55 Quality of life is similar in patients with chronic stable heart failure on either vasodilating or non-vasodilating beta blockers. modified kansas city cardiomyopathy questionnaire

Author

Pharithi, R, primary, Egom, E, additional, Maher, A, additional, Fall, S, additional, Fahy, S, additional, Jago, A, additional, Mannion, T, additional, Delaney, L, additional, Khan, B, additional, Yearoo, I, additional, Murphy, C, additional, and Maher, V, additional

Published
2017
Full Text
View/download PDF

38. Four novel loci (19q13, 6q24, 12q24, and 5q14) influence the microcirculation In vivo

Author

Ikram MK, Sim X, Jensen RA, Cotch MF, Hewitt AW, Ikram MA, Wang JJ, Klein R, Klein BE, Breteler MM, Cheung N, Liew G, Mitchell P, Uitterlinden AG, Rivadeneira F, Hofman A, de Jong PT, van Duijn CM, Kao L, Cheng CY, Smith AV, Glazer NL, Lumley T, McKnight B, Psaty BM, Jonasson F, Eiriksdottir G, Aspelund T, Newton Cheh C, Johnson T, Gateva V, Tobin MD, Bochud M, Coin L, Najjar S, Zhao JH, Heath SC, Eyheramendy S, Wallace C, Chambers JC, Khaw KT, Polidoro S, Grobbee DE, Onland Moret NC, Allione A, Di Gregorio A, Guarrera S, Ricceri F, Romanazzi V, Sacerdote C, Vineis P, Barroso I, O'Reilly PF, Peltonen L, Pouta A, de Jong PE, Snieder P, Tognoni G, Lakatta EG, Sanna S, Scheet P, Schlessinger D, Scuteri A, Galan P, Gut IV, Hercberg S, van der Schouw YT, Numans ME, Matullo G, Navis G, Berglund G, Bandinelli S, Ferrucci L, Watkins H, Tuomilehto J, Altshuler D, Wareham NJ, Uda M, Jarvelin MR, Mooser V, Melander O, Loos RFJ, Elliott P, Abecasis GR, Caulfield M, Munroe PB, Harris TB, Launer LJ, Taylor KD, Li X, Iyengar SK, Xi Q, Sivakumaran TA, Mackey DA, Macgregor S, Martin NG, Young TL, Bis JC, Wiggins KL, Heckbert SR, Hammond CJ, Andrew T, Fahy S, Attia J, Holliday EG, Scott RJ, Islam FM, Rotter JI, McAuley AK, Boerwinkle E, Tai ES, Gudnason V, Siscovick DS, Vingerling JR, Wong TY, PANICO, SALVATORE, Ophthalmology, Epidemiology, Internal Medicine, Faculteit der Geneeskunde, Ikram, Mk, Xueling, S, Jensen, Ra, Cotch, Mf, Hewitt, Aw, Ikram, Ma, Wang, Jj, Klein, R, Klein, Be, Breteler, Mm, Cheung, N, Liew, G, Mitchell, P, Uitterlinden, Ag, Rivadeneira, F, Hofman, A, de Jong, Pt, van Duijn, Cm, Kao, L, Cheng, Cy, Smith, Av, Glazer, Nl, Lumley, T, Mcknight, B, Psaty, Bm, Jonasson, F, Eiriksdottir, G, Aspelund, T, Panico, Salvatore, Global BPgen, Consortium, Harris, Tb, Launer, Lj, Taylor, Kd, Li, X, Iyengar, Sk, Xi, Q, Sivakumaran, Ta, Mackey, Da, Macgregor, S, Martin, Ng, Young, Tl, Bis, Jc, Wiggins, Kl, Heckbert, Sr, Hammond, Cj, Andrew, T, Fahy, S, Attia, J, Holliday, Eg, Scott, Rj, Islam, Fm, Rotter, Ji, Mcauley, Ak, Boerwinkle, E, Tai, E, Gudnason, V, Siscovick, D, Vingerling, Jr, 2010 Oct 28, Wong T. Y. PLoS G. e. n. e. t., 6:e1001184, Sim, X, Newton Cheh, C, Johnson, T, Gateva, V, Tobin, Md, Bochud, M, Coin, L, Najjar, S, Zhao, Jh, Heath, Sc, Eyheramendy, S, Wallace, C, Chambers, Jc, Khaw, Kt, Polidoro, S, Grobbee, De, Onland Moret, Nc, Allione, A, Di Gregorio, A, Guarrera, S, Ricceri, F, Romanazzi, V, Sacerdote, C, Vineis, P, Barroso, I, O'Reilly, Pf, Peltonen, L, Pouta, A, de Jong, Pe, Snieder, P, Tognoni, G, Lakatta, Eg, Sanna, S, Scheet, P, Schlessinger, D, Scuteri, A, Galan, P, Gut, Iv, Hercberg, S, van der Schouw, Yt, Numans, Me, Matullo, G, Navis, G, Berglund, G, Bandinelli, S, Ferrucci, L, Watkins, H, Tuomilehto, J, Altshuler, D, Wareham, Nj, Uda, M, Jarvelin, Mr, Mooser, V, Melander, O, Loos, Rfj, Elliott, P, Abecasis, Gr, Caulfield, M, Munroe, Pb, Wong, Ty, Medical Research Council (MRC), and Department of Public Health

Subjects
Male, Cancer Research, Pathology, VESSEL DIAMETERS, Genome-wide association study, 030204 cardiovascular system & hematology, QH426-470, DISEASE, Pathogenesis, Cohort Studies, chemistry.chemical_compound, 0302 clinical medicine, Cardiovascular Disorders/Vascular Biology, Child, Genetics (clinical), Genetics, Aged, 80 and over, 0303 health sciences, education.field_of_study, Middle Aged, 314 Health sciences, 3. Good health, Cardiovascular Diseases, Child, Preschool, Chromosomes, Human, Pair 5, Chromosomes, Human, Pair 6, Female, Research Article, Adult, medicine.medical_specialty, Adolescent, ANTIHYPERTENSIVE DRUG THERAPIES, Population, European Continental Ancestry Group, Locus (genetics), Single-nucleotide polymorphism, ATHEROSCLEROSIS RISK, Biology, Polymorphism, Single Nucleotide, White People, Microcirculation, 03 medical and health sciences, Young Adult, AGE, Meta-Analysis as Topic, SDG 3 - Good Health and Well-being, Genetics and Genomics/Population Genetics, medicine, SNP, Humans, GENOME-WIDE ASSOCIATION, education, Molecular Biology, Ecology, Evolution, Behavior and Systematics, METAANALYSIS, Global BPgen Consortium, 030304 developmental biology, Aged, 0604 Genetics, Chromosomes, Human, Pair 12, Retinal Vessels, Retinal, CHARGE CONSORTIUM, RETINAL VASCULAR CALIBER, chemistry, Genetic Loci, Ophthalmology/Retinal Disorders, genome-wide association study, microcirculation, GENE/ENVIRONMENT SUSCEPTIBILITY-REYKJAVIK, Chromosomes, Human, Pair 19, Developmental Biology, Genome-Wide Association Study
Abstract

There is increasing evidence that the microcirculation plays an important role in the pathogenesis of cardiovascular diseases. Changes in retinal vascular caliber reflect early microvascular disease and predict incident cardiovascular events. We performed a genome-wide association study to identify genetic variants associated with retinal vascular caliber. We analyzed data from four population-based discovery cohorts with 15,358 unrelated Caucasian individuals, who are members of the Cohort for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium, and replicated findings in four independent Caucasian cohorts (n = 6,652). All participants had retinal photography and retinal arteriolar and venular caliber measured from computer software. In the discovery cohorts, 179 single nucleotide polymorphisms (SNP) spread across five loci were significantly associated (p, Author Summary The microcirculation plays an important role in the development of cardiovascular diseases. Retinal vascular caliber changes reflect early microvascular disease and predict incident cardiovascular events. In order to identify genetic variants associated with retinal vascular caliber, we performed a genome-wide association study and analyzed data from four population-based discovery cohorts with 15,358 unrelated Caucasian individuals, who are members of the Cohort for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium, and replicated findings in four independent Caucasian cohorts (n = 6,652). We found evidence for association of four loci with retinal venular caliber: on chromosomes 19q13 within the RASIP1 locus, 6q24 adjacent to the VTA1 and NMBR loci, 12q24 in the region of ATXN2,SH2B3 and PTPN11 loci, and 5q14 adjacent to the MEF2C locus. In two independent samples, locus 12q24 was also associated with coronary heart disease and hypertension. In the present study, we demonstrate that four novel loci were associated with retinal venular caliber, an endophenotype of the microcirculation associated with clinical cardiovascular disease. Our findings will help focus research on novel genes and pathways involving the microcirculation and its role in the development of cardiovascular disease.

Published
2010

39. The origin of incipient ferroelectricity in lead telluride

Author

Jiang, M. P., primary, Trigo, M., additional, Savić, I., additional, Fahy, S., additional, Murray, É. D., additional, Bray, C., additional, Clark, J., additional, Henighan, T., additional, Kozina, M., additional, Chollet, M., additional, Glownia, J. M., additional, Hoffmann, M. C., additional, Zhu, D., additional, Delaire, O., additional, May, A. F., additional, Sales, B. C., additional, Lindenberg, A. M., additional, Zalden, P., additional, Sato, T., additional, Merlin, R., additional, and Reis, D. A., additional

Published
2016
Full Text
View/download PDF

42. Direct measurement and analysis of the conduction band density of states in diluted GaAs $_{1 − x}$ N $_{x}$ alloys

Author

Ivanova, L., Eisele, H., Riechert, H., O’Reilly, E. P., Vaughan, M. P., Ebert, Ph., Lenz, A., Timm, R., Schumann, O., Geelhaar, L., Dähne, M., and Fahy, S.

Subjects
ddc:530
Abstract

We use scanning tunneling spectroscopy to show directly that the conduction band density of states (DOS) of GaAs1−xNx with low nitrogen (N) content x is enhanced about 0.5 eV above the band edge, followed by a decrease at higher energy. The structure of the measured DOS is in excellent agreement with calculations based on a Green’s-function formalism taking into account different N environments. This analysis highlights the inclusion of N-N pairs and the validity of the Green’s-function approach to describe the band structure of dilute nitride and related extreme semiconductor alloys.

Published
2010
Full Text
View/download PDF

44. Resonant Raman-active localized vibrational modes in AlyGa{1-y}NxAs{1-x} alloys: Experiment and firstprinciples calculations

Author

Teweldeberhan, A.M., Stenuit, G., Fahy, S., Gallardo Velasco, Eva María, Lazic, Snezana, Calleja Pardo, José Manuel, Miguel-Sanchez, J., Montes Bajo, Miguel, Hierro Cano, Adrián, Gargallo Caballero, Raquel, Fernández González, Alvaro de Guzmán, and Muñoz Merino, Elias

Subjects
Telecomunicaciones, Materiales, Energía Eléctrica
Abstract

The localized vibrational modes associated with substitutional aluminium and nitrogen atoms in AlyGa1−yNxAs1−x have been studied within first-principles density functional theory using a supercell approach. Localized vibrational modes related to N-AlmGa4−m (1≤m≥4) complexes have been identified, which reveal the formation of N-Al4 units well above random abundance, in qualitative agreement with a large calculated value (391 meV) of the Al-N bond formation energy. We determine the resonant Raman-active modes from the selection rule obtained by calculating the electron-phonon coupling strength and optical transition matrix elements and compare them with resonant Raman spectroscopy measurements. The localized modes from Raman scattering measurements with frequencies around 325, 385, 400, 450, 500, and 540 cm−1 are found to be in good agreement with the calculated modes (326, 364, 384, 410, 456, 507, and 556 cm−1). The modes are classified as follows: the two modes at 326 and 556 cm−1 belong to the N-AlGa3 configuration; there are three modes which belong to N-Al2Ga2 with frequencies at 326, 364, and 507 cm−1; the N-Al3Ga configuration gives rise to modes whose frequencies are 384 and 456 cm−1; and the mode at a frequency of 410 cm−1 belongs to the N-Al4 complex. The comparison of line intensities from samples before and after rapid thermal annealing allows us to experimentally distinguish vibrational modes associated with different clusters, in agreement with the theoretical assignments.

Published
2008

47. Supersonic strain front driven by a dense electron-hole plasma

Author

DeCamp, M. F., Reis, D. A., Cavalieri, A., Bucksbaum, P. H., Clarke, R., Merlin, R., Dufresne, E. M., Arms, D. A., Lindenberg, A. M., MacPhee, A. G., Chang, Z., Lings, B., Wark, J. S., and Fahy, S.

Subjects
Condensed Matter - Materials Science, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences
Abstract

We study coherent strain in (001) Ge generated by an ultrafast laser-initiated high density electron-hole plasma. The resultant coherent pulse is probed by time-resolved x-ray diffraction through changes in the anomalous transmission. The acoustic pulse front is driven by ambipolar diffusion of the electron-hole plasma and propagates into the crystal at supersonic speeds. Simulations of the strain including electron-phonon coupling, modified by carrier diffusion and Auger recombination, are in good agreement with the observed dynamics., Comment: 4 pages, 6 figures

Published
2003
Full Text
View/download PDF

48. Calculations of the A(1) phonon frequency in photoexcited tellurium

Author

Tangney, P. and Fahy, S.

Subjects
Condensed Matter - Materials Science, Silicon, Initio molecular dynamics, GaAs, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Density, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Condensed Matter::Materials Science, Condensed Matter::Superconductivity, Carriers, Condensed Matter::Strongly Correlated Electrons, Si, Physics::Chemical Physics, Approximation, Bonding properties
Abstract

Calculations of the A_1 phonon frequency in photoexcited tellurium are presented. The phonon frequency as a function of photoexcited carrier density and phonon amplitude is determined. Recent pump probe experiments are interpreted in the light of these calculatons. It is proposed that, in conjunction with measurements of the phonon period in ultra-fast pump-probe reflectivity experiments, the calculated frequency shifts can be used to infer the evolution of the density of photoexcited carriers on a sub-picosecond time-scale., 15 pages Latex, 3 postscript figures

Published
1999

49. Four novel loci (19q13, 6q24, 12q24, and 5q14) influence the microcirculation In vivo

Author

Ikram, M.K. (Kamran), Xueling, S. (Sim), Jensen, R.A. (Richard), Cotch, M.F. (Mary Frances), Hewit, A.W. (Alex), Ikram, M.A. (Arfan), Wang, J.J. (Jie Jin), Klein, B.E.K. (Barbara), Breteler, M.M.B. (Monique), Cheung, N. (Ning), Liew, G. (Gerald), Mitchell, P. (Paul), Uitterlinden, A.G. (André), Rivadeneira Ramirez, F. (Fernando), Hofman, A. (Albert), Jong, P.T.V.M. (Paulus) de, Duijn, C.M. (Cornelia) van, Kao, L. (Linda), Cheng, C-Y. (Ching-Yu), Smith, A.V. (Albert Vernon), Glazer, N.L. (Nicole), Lumley, T. (Thomas), McKnight, B. (Barbara), Psaty, B.M. (Bruce), Jonasson, F. (Fridbert), Eiriksdottir, G. (Gudny), Aspelund, T. (Thor), Harris, T.B. (Tamara), Launer, L.J. (Lenore), Taylor, K.D. (Kent), Li, X. (Xiaohui), Sivakumaran, T.A. (Theru), Mackey, D.A. (David), MacGregor, S. (Stuart), Martin, N.G. (Nicholas), Young, T.L. (Terry), Bis, J.C. (Joshua), Wiggins, K.L. (Kerri), Heckbert, S.R. (Susan), Hammond, C.J. (Christopher), Andrew, T. (Toby), Fahy, S. (Samantha), Attia, J. (John), Holliday, E.G. (Elizabeth), Scott, R.J. (Rodney), Islam, F.M.A. (Amirul), Rotter, J.I. (Jerome), McAuley, A.K. (Annie), Boerwinkle, E.A. (Eric), Tai, E.S. (Shyong), Gudnason, V. (Vilmundur), Siscovick, D.S. (David), Vingerling, J.R. (Hans), Wong, T.Y. (Tien Yin), Ikram, M.K. (Kamran), Xueling, S. (Sim), Jensen, R.A. (Richard), Cotch, M.F. (Mary Frances), Hewit, A.W. (Alex), Ikram, M.A. (Arfan), Wang, J.J. (Jie Jin), Klein, B.E.K. (Barbara), Breteler, M.M.B. (Monique), Cheung, N. (Ning), Liew, G. (Gerald), Mitchell, P. (Paul), Uitterlinden, A.G. (André), Rivadeneira Ramirez, F. (Fernando), Hofman, A. (Albert), Jong, P.T.V.M. (Paulus) de, Duijn, C.M. (Cornelia) van, Kao, L. (Linda), Cheng, C-Y. (Ching-Yu), Smith, A.V. (Albert Vernon), Glazer, N.L. (Nicole), Lumley, T. (Thomas), McKnight, B. (Barbara), Psaty, B.M. (Bruce), Jonasson, F. (Fridbert), Eiriksdottir, G. (Gudny), Aspelund, T. (Thor), Harris, T.B. (Tamara), Launer, L.J. (Lenore), Taylor, K.D. (Kent), Li, X. (Xiaohui), Sivakumaran, T.A. (Theru), Mackey, D.A. (David), MacGregor, S. (Stuart), Martin, N.G. (Nicholas), Young, T.L. (Terry), Bis, J.C. (Joshua), Wiggins, K.L. (Kerri), Heckbert, S.R. (Susan), Hammond, C.J. (Christopher), Andrew, T. (Toby), Fahy, S. (Samantha), Attia, J. (John), Holliday, E.G. (Elizabeth), Scott, R.J. (Rodney), Islam, F.M.A. (Amirul), Rotter, J.I. (Jerome), McAuley, A.K. (Annie), Boerwinkle, E.A. (Eric), Tai, E.S. (Shyong), Gudnason, V. (Vilmundur), Siscovick, D.S. (David), Vingerling, J.R. (Hans), and Wong, T.Y. (Tien Yin)

Abstract

There is increasing evidence that the microcirculation plays an important role in the pathogenesis of cardiovascular diseases. Changes in retinal vascular caliber reflect early microvascular disease and predict incident cardiovascular events. We performed a genome-wide association study to identify genetic variants associated with retinal vascular caliber. We analyzed data from four population-based discovery cohorts with 15,358 unrelated Caucasian individuals, who are members of the Cohort for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium, and replicated findings in four independent Caucasian cohorts (n = 6,652). All participants had retinal photography and retinal arteriolar and venular caliber measured from computer software. In the discovery cohorts, 179 single nucleotide polymorphisms (SNP) spread across five loci were significantly associated (p<5.0×10-8) with retinal venular caliber, but none showed association with arteriolar caliber. Collectively, these five loci explain 1.0%-3.2% of the variation in retinal venular caliber. Four out of these five loci were confirmed in independent replication samples. In the combined analyses, the top SNPs at each locus were: rs2287921 (19q13; p = 1.61×10-25, within the RASIP1 locus), rs225717 (6q24; p = 1.25×10-16, adjacent to the VTA1 and NMBR loci), rs10774625 (12q24; p = 2.15×10-13, in the region of ATXN2,SH2B3 and PTPN11 loci), and rs17421627 (5q14; p = 7.32×10-16, adjacent to the MEF2C locus). In two independent samples, locus 12q24 was also associated with coronary heart disease and hypertension. Our population-based genome-wide association study demonstrates four novel loci associated with retinal venular caliber, an endophenotype of the microcirculation associated with clinical cardiovascular disease. These data provide further insights into the contribution and biological mechanisms of microcirculatory changes that underlie cardiovascular disease.

Published
2010
Full Text
View/download PDF

50. Four Novel Loci (19q13, 6q24, 12q24, and 5q14) Influence the Microcirculation In Vivo

Author

McCarthy, MI, Ikram, MK, Xueling, S, Jensen, RA, Cotch, MF, Hewitt, AW, Ikram, MA, Wang, JJ, Klein, R, Klein, BEK, Breteler, MMB, Cheung, N, Liew, G, Mitchell, P, Uitterlinden, AG, Rivadeneira, F, Hofman, A, de Jong, PTVM, van Duijn, CM, Kao, L, Cheng, C-Y, Smith, AV, Glazer, NL, Lumley, T, McKnight, B, Psaty, BM, Jonasson, F, Eiriksdottir, G, Aspelund, T, Harris, TB, Launer, LJ, Taylor, KD, Li, X, Iyengar, SK, Xi, Q, Sivakumaran, TA, Mackey, DA, MacGregor, S, Martin, NG, Young, TL, Bis, JC, Wiggins, KL, Heckbert, SR, Hammond, CJ, Andrew, T, Fahy, S, Attia, J, Holliday, EG, Scott, RJ, Islam, FMA, Rotter, JI, McAuley, AK, Boerwinkle, E, Tai, ES, Gudnason, V, Siscovick, DS, Vingerling, JR, Wong, TY, McCarthy, MI, Ikram, MK, Xueling, S, Jensen, RA, Cotch, MF, Hewitt, AW, Ikram, MA, Wang, JJ, Klein, R, Klein, BEK, Breteler, MMB, Cheung, N, Liew, G, Mitchell, P, Uitterlinden, AG, Rivadeneira, F, Hofman, A, de Jong, PTVM, van Duijn, CM, Kao, L, Cheng, C-Y, Smith, AV, Glazer, NL, Lumley, T, McKnight, B, Psaty, BM, Jonasson, F, Eiriksdottir, G, Aspelund, T, Harris, TB, Launer, LJ, Taylor, KD, Li, X, Iyengar, SK, Xi, Q, Sivakumaran, TA, Mackey, DA, MacGregor, S, Martin, NG, Young, TL, Bis, JC, Wiggins, KL, Heckbert, SR, Hammond, CJ, Andrew, T, Fahy, S, Attia, J, Holliday, EG, Scott, RJ, Islam, FMA, Rotter, JI, McAuley, AK, Boerwinkle, E, Tai, ES, Gudnason, V, Siscovick, DS, Vingerling, JR, and Wong, TY

Abstract

There is increasing evidence that the microcirculation plays an important role in the pathogenesis of cardiovascular diseases. Changes in retinal vascular caliber reflect early microvascular disease and predict incident cardiovascular events. We performed a genome-wide association study to identify genetic variants associated with retinal vascular caliber. We analyzed data from four population-based discovery cohorts with 15,358 unrelated Caucasian individuals, who are members of the Cohort for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium, and replicated findings in four independent Caucasian cohorts (n = 6,652). All participants had retinal photography and retinal arteriolar and venular caliber measured from computer software. In the discovery cohorts, 179 single nucleotide polymorphisms (SNP) spread across five loci were significantly associated (p<5.0×10(-8)) with retinal venular caliber, but none showed association with arteriolar caliber. Collectively, these five loci explain 1.0%-3.2% of the variation in retinal venular caliber. Four out of these five loci were confirmed in independent replication samples. In the combined analyses, the top SNPs at each locus were: rs2287921 (19q13; p = 1.61×10(-25), within the RASIP1 locus), rs225717 (6q24; p = 1.25×10(-16), adjacent to the VTA1 and NMBR loci), rs10774625 (12q24; p = 2.15×10(-13), in the region of ATXN2,SH2B3 and PTPN11 loci), and rs17421627 (5q14; p = 7.32×10(-16), adjacent to the MEF2C locus). In two independent samples, locus 12q24 was also associated with coronary heart disease and hypertension. Our population-based genome-wide association study demonstrates four novel loci associated with retinal venular caliber, an endophenotype of the microcirculation associated with clinical cardiovascular disease. These data provide further insights into the contribution and biological mechanisms of microcirculatory changes that underlie cardiovascular disease.

Published
2010

Catalog

Books, media, physical & digital resources
See catalog results