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POPULATION MORTALITY AND CYCLICITY AS AFFECTED BY INTRASPECIFIC COMPETITION1,2
- R. E. Stinner, J. W. Jones, C. Tuttle, R. E. Caron
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- Journal:
- The Canadian Entomologist / Volume 109 / Issue 6 / June 1977
- Published online by Cambridge University Press:
- 31 May 2012, pp. 879-890
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A model for intraspecific competition that incorporates the effects of inter- and intra-stage survival rates, spatial distribution, and variation in growth is developed using basic probability theory. Simulation results for cannibalism in Heliothis zea (Boddie) are presented and intraspecific competition is shown to have effects on population cyclicity and on mortality.
SIMULATION OF TEMPERATURE-DEPENDENT DEVELOPMENT IN POPULATION DYNAMICS MODELS12
- R. E. Stinner, G. D. Butler, Jr., J. S. Bacheler, C. Tuttle
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- Journal:
- The Canadian Entomologist / Volume 107 / Issue 11 / November 1975
- Published online by Cambridge University Press:
- 31 May 2012, pp. 1167-1174
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The simulation of variability in temperature-dependent development is discussed. An algorithm for simulation of this variability is developed and validated under constant and variable temperature regimes for Anthonomus grandis, Trichoplusia ni, and Heliothis zea.
Contributors
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- By Rose Teteki Abbey, K. C. Abraham, David Tuesday Adamo, LeRoy H. Aden, Efrain Agosto, Victor Aguilan, Gillian T. W. Ahlgren, Charanjit Kaur AjitSingh, Dorothy B E A Akoto, Giuseppe Alberigo, Daniel E. Albrecht, Ruth Albrecht, Daniel O. Aleshire, Urs Altermatt, Anand Amaladass, Michael Amaladoss, James N. Amanze, Lesley G. Anderson, Thomas C. Anderson, Victor Anderson, Hope S. Antone, María Pilar Aquino, Paula Arai, Victorio Araya Guillén, S. Wesley Ariarajah, Ellen T. Armour, Brett Gregory Armstrong, Atsuhiro Asano, Naim Stifan Ateek, Mahmoud Ayoub, John Alembillah Azumah, Mercedes L. García Bachmann, Irena Backus, J. Wayne Baker, Mieke Bal, Lewis V. Baldwin, William Barbieri, António Barbosa da Silva, David Basinger, Bolaji Olukemi Bateye, Oswald Bayer, Daniel H. Bays, Rosalie Beck, Nancy Elizabeth Bedford, Guy-Thomas Bedouelle, Chorbishop Seely Beggiani, Wolfgang Behringer, Christopher M. Bellitto, Byard Bennett, Harold V. Bennett, Teresa Berger, Miguel A. Bernad, Henley Bernard, Alan E. Bernstein, Jon L. Berquist, Johannes Beutler, Ana María Bidegain, Matthew P. Binkewicz, Jennifer Bird, Joseph Blenkinsopp, Dmytro Bondarenko, Paulo Bonfatti, Riet en Pim Bons-Storm, Jessica A. Boon, Marcus J. Borg, Mark Bosco, Peter C. Bouteneff, François Bovon, William D. Bowman, Paul S. Boyer, David Brakke, Richard E. Brantley, Marcus Braybrooke, Ian Breward, Ênio José da Costa Brito, Jewel Spears Brooker, Johannes Brosseder, Nicholas Canfield Read Brown, Robert F. Brown, Pamela K. Brubaker, Walter Brueggemann, Bishop Colin O. Buchanan, Stanley M. Burgess, Amy Nelson Burnett, J. Patout Burns, David B. Burrell, David Buttrick, James P. Byrd, Lavinia Byrne, Gerado Caetano, Marcos Caldas, Alkiviadis Calivas, William J. Callahan, Salvatore Calomino, Euan K. Cameron, William S. Campbell, Marcelo Ayres Camurça, Daniel F. Caner, Paul E. Capetz, Carlos F. Cardoza-Orlandi, Patrick W. Carey, Barbara Carvill, Hal Cauthron, Subhadra Mitra Channa, Mark D. Chapman, James H. Charlesworth, Kenneth R. Chase, Chen Zemin, Luciano Chianeque, Philip Chia Phin Yin, Francisca H. Chimhanda, Daniel Chiquete, John T. Chirban, Soobin Choi, Robert Choquette, Mita Choudhury, Gerald Christianson, John Chryssavgis, Sejong Chun, Esther Chung-Kim, Charles M. A. Clark, Elizabeth A. Clark, Sathianathan Clarke, Fred Cloud, John B. Cobb, W. Owen Cole, John A Coleman, John J. Collins, Sylvia Collins-Mayo, Paul K. Conkin, Beth A. Conklin, Sean Connolly, Demetrios J. Constantelos, Michael A. Conway, Paula M. Cooey, Austin Cooper, Michael L. Cooper-White, Pamela Cooper-White, L. William Countryman, Sérgio Coutinho, Pamela Couture, Shannon Craigo-Snell, James L. Crenshaw, David Crowner, Humberto Horacio Cucchetti, Lawrence S. Cunningham, Elizabeth Mason Currier, Emmanuel Cutrone, Mary L. Daniel, David D. Daniels, Robert Darden, Rolf Darge, Isaiah Dau, Jeffry C. Davis, Jane Dawson, Valentin Dedji, John W. de Gruchy, Paul DeHart, Wendy J. Deichmann Edwards, Miguel A. De La Torre, George E. Demacopoulos, Thomas de Mayo, Leah DeVun, Beatriz de Vasconcellos Dias, Dennis C. Dickerson, John M. Dillon, Luis Miguel Donatello, Igor Dorfmann-Lazarev, Susanna Drake, Jonathan A. Draper, N. Dreher Martin, Otto Dreydoppel, Angelyn Dries, A. J. Droge, Francis X. D'Sa, Marilyn Dunn, Nicole Wilkinson Duran, Rifaat Ebied, Mark J. Edwards, William H. Edwards, Leonard H. Ehrlich, Nancy L. Eiesland, Martin Elbel, J. Harold Ellens, Stephen Ellingson, Marvin M. Ellison, Robert Ellsberg, Jean Bethke Elshtain, Eldon Jay Epp, Peter C. Erb, Tassilo Erhardt, Maria Erling, Noel Leo Erskine, Gillian R. Evans, Virginia Fabella, Michael A. Fahey, Edward Farley, Margaret A. Farley, Wendy Farley, Robert Fastiggi, Seena Fazel, Duncan S. Ferguson, Helwar Figueroa, Paul Corby Finney, Kyriaki Karidoyanes FitzGerald, Thomas E. FitzGerald, John R. Fitzmier, Marie Therese Flanagan, Sabina Flanagan, Claude Flipo, Ronald B. Flowers, Carole Fontaine, David Ford, Mary Ford, Stephanie A. Ford, Jim Forest, William Franke, Robert M. Franklin, Ruth Franzén, Edward H. Friedman, Samuel Frouisou, Lorelei F. Fuchs, Jojo M. Fung, Inger Furseth, Richard R. Gaillardetz, Brandon Gallaher, China Galland, Mark Galli, Ismael García, Tharscisse Gatwa, Jean-Marie Gaudeul, Luis María Gavilanes del Castillo, Pavel L. Gavrilyuk, Volney P. Gay, Metropolitan Athanasios Geevargis, Kondothra M. George, Mary Gerhart, Simon Gikandi, Maurice Gilbert, Michael J. Gillgannon, Verónica Giménez Beliveau, Terryl Givens, Beth Glazier-McDonald, Philip Gleason, Menghun Goh, Brian Golding, Bishop Hilario M. Gomez, Michelle A. Gonzalez, Donald K. Gorrell, Roy Gottfried, Tamara Grdzelidze, Joel B. Green, Niels Henrik Gregersen, Cristina Grenholm, Herbert Griffiths, Eric W. Gritsch, Erich S. Gruen, Christoffer H. Grundmann, Paul H. Gundani, Jon P. Gunnemann, Petre Guran, Vidar L. Haanes, Jeremiah M. Hackett, Getatchew Haile, Douglas John Hall, Nicholas Hammond, Daphne Hampson, Jehu J. Hanciles, Barry Hankins, Jennifer Haraguchi, Stanley S. Harakas, Anthony John Harding, Conrad L. Harkins, J. William Harmless, Marjory Harper, Amir Harrak, Joel F. Harrington, Mark W. Harris, Susan Ashbrook Harvey, Van A. Harvey, R. Chris Hassel, Jione Havea, Daniel Hawk, Diana L. Hayes, Leslie Hayes, Priscilla Hayner, S. Mark Heim, Simo Heininen, Richard P. Heitzenrater, Eila Helander, David Hempton, Scott H. Hendrix, Jan-Olav Henriksen, Gina Hens-Piazza, Carter Heyward, Nicholas J. Higham, David Hilliard, Norman A. Hjelm, Peter C. Hodgson, Arthur Holder, M. Jan Holton, Dwight N. Hopkins, Ronnie Po-chia Hsia, Po-Ho Huang, James Hudnut-Beumler, Jennifer S. Hughes, Leonard M. Hummel, Mary E. Hunt, Laennec Hurbon, Mark Hutchinson, Susan E. Hylen, Mary Beth Ingham, H. Larry Ingle, Dale T. Irvin, Jon Isaak, Paul John Isaak, Ada María Isasi-Díaz, Hans Raun Iversen, Margaret C. Jacob, Arthur James, Maria Jansdotter-Samuelsson, David Jasper, Werner G. Jeanrond, Renée Jeffery, David Lyle Jeffrey, Theodore W. Jennings, David H. Jensen, Robin Margaret Jensen, David Jobling, Dale A. Johnson, Elizabeth A. Johnson, Maxwell E. Johnson, Sarah Johnson, Mark D. Johnston, F. Stanley Jones, James William Jones, John R. Jones, Alissa Jones Nelson, Inge Jonsson, Jan Joosten, Elizabeth Judd, Mulambya Peggy Kabonde, Robert Kaggwa, Sylvester Kahakwa, Isaac Kalimi, Ogbu U. Kalu, Eunice Kamaara, Wayne C. Kannaday, Musimbi Kanyoro, Veli-Matti Kärkkäinen, Frank Kaufmann, Léon Nguapitshi Kayongo, Richard Kearney, Alice A. Keefe, Ralph Keen, Catherine Keller, Anthony J. Kelly, Karen Kennelly, Kathi Lynn Kern, Fergus Kerr, Edward Kessler, George Kilcourse, Heup Young Kim, Kim Sung-Hae, Kim Yong-Bock, Kim Yung Suk, Richard King, Thomas M. King, Robert M. Kingdon, Ross Kinsler, Hans G. Kippenberg, Cheryl A. 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Lotz, Andrew Louth, Robin W. Lovin, William Luis, Frank D. Macchia, Diarmaid N. J. MacCulloch, Kirk R. MacGregor, Marjory A. MacLean, Donald MacLeod, Tomas S. Maddela, Inge Mager, Laurenti Magesa, David G. Maillu, Fortunato Mallimaci, Philip Mamalakis, Kä Mana, Ukachukwu Chris Manus, Herbert Robinson Marbury, Reuel Norman Marigza, Jacqueline Mariña, Antti Marjanen, Luiz C. L. Marques, Madipoane Masenya (ngwan'a Mphahlele), Caleb J. D. Maskell, Steve Mason, Thomas Massaro, Fernando Matamoros Ponce, András Máté-Tóth, Odair Pedroso Mateus, Dinis Matsolo, Fumitaka Matsuoka, John D'Arcy May, Yelena Mazour-Matusevich, Theodore Mbazumutima, John S. McClure, Christian McConnell, Lee Martin McDonald, Gary B. McGee, Thomas McGowan, Alister E. McGrath, Richard J. McGregor, John A. McGuckin, Maud Burnett McInerney, Elsie Anne McKee, Mary B. McKinley, James F. McMillan, Ernan McMullin, Kathleen E. McVey, M. 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Phan, Isabel Apawo Phiri, William S. F. Pickering, Derrick G. Pitard, William Elvis Plata, Zlatko Plese, John Plummer, James Newton Poling, Ronald Popivchak, Andrew Porter, Ute Possekel, James M. Powell, Enos Das Pradhan, Devadasan Premnath, Jaime Adrían Prieto Valladares, Anne Primavesi, Randall Prior, María Alicia Puente Lutteroth, Eduardo Guzmão Quadros, Albert Rabil, Laurent William Ramambason, Apolonio M. Ranche, Vololona Randriamanantena Andriamitandrina, Lawrence R. Rast, Paul L. Redditt, Adele Reinhartz, Rolf Rendtorff, Pål Repstad, James N. Rhodes, John K. Riches, Joerg Rieger, Sharon H. Ringe, Sandra Rios, Tyler Roberts, David M. Robinson, James M. Robinson, Joanne Maguire Robinson, Richard A. H. Robinson, Roy R. Robson, Jack B. Rogers, Maria Roginska, Sidney Rooy, Rev. Garnett Roper, Maria José Fontelas Rosado-Nunes, Andrew C. Ross, Stefan Rossbach, François Rossier, John D. Roth, John K. Roth, Phillip Rothwell, Richard E. 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Stewart, Cynthia Stokes Brown, Ken Stone, Anne Stott, Elizabeth Stuart, Monya Stubbs, Marjorie Hewitt Suchocki, David Kwang-sun Suh, Scott W. Sunquist, Keith Suter, Douglas Sweeney, Charles H. Talbert, Shawqi N. Talia, Elsa Tamez, Joseph B. Tamney, Jonathan Y. Tan, Yak-Hwee Tan, Kathryn Tanner, Feiya Tao, Elizabeth S. Tapia, Aquiline Tarimo, Claire Taylor, Mark Lewis Taylor, Bishop Abba Samuel Wolde Tekestebirhan, Eugene TeSelle, M. Thomas Thangaraj, David R. Thomas, Andrew Thornley, Scott Thumma, Marcelo Timotheo da Costa, George E. “Tink” Tinker, Ola Tjørhom, Karen Jo Torjesen, Iain R. Torrance, Fernando Torres-Londoño, Archbishop Demetrios [Trakatellis], Marit Trelstad, Christine Trevett, Phyllis Trible, Johannes Tromp, Paul Turner, Robert G. Tuttle, Archbishop Desmond Tutu, Peter Tyler, Anders Tyrberg, Justin Ukpong, Javier Ulloa, Camillus Umoh, Kristi Upson-Saia, Martina Urban, Monica Uribe, Elochukwu Eugene Uzukwu, Richard Vaggione, Gabriel Vahanian, Paul Valliere, T. J. 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Yee, Viktor Yelensky, Yeo Khiok-Khng, Gustav K. K. Yeung, Angela Yiu, Amos Yong, Yong Ting Jin, You Bin, Youhanna Nessim Youssef, Eliana Yunes, Robert Michael Zaller, Valarie H. Ziegler, Barbara Brown Zikmund, Joyce Ann Zimmerman, Aurora Zlotnik, Zhuo Xinping
- Edited by Daniel Patte, Vanderbilt University, Tennessee
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- The Cambridge Dictionary of Christianity
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- 05 August 2012
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- 20 September 2010, pp xi-xliv
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Surveillance for severe community-associated methicillin-resistant Staphylococcus aureus infection
- P. WIERSMA, M. TOBIN D'ANGELO, W. R. DALEY, J. TUTTLE, K. E. ARNOLD, S. M. RAY, J. L. LADSON, S. N. BULENS, C. L. DRENZEK
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- Epidemiology & Infection / Volume 137 / Issue 12 / December 2009
- Published online by Cambridge University Press:
- 15 April 2009, pp. 1674-1678
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Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has rapidly emerged in the USA as a cause of severe infections in previously healthy persons without traditional risk factors. We describe the epidemiology of severe CA-MRSA disease in the state of Georgia, USA and analyse the risk of death associated with three different clinical syndromes of CA-MRSA disease – pneumonia, invasive disease, and skin and soft-tissue infections (SSTIs). A total of 1670 cases of severe CA-MRSA disease were reported during 2005–2007. The case-fatality rate was 3·4%; sex and race of fatal and non-fatal cases did not differ significantly. While CA-MRSA pneumonia and invasive disease were less common than SSTIs, they were about 15 times more likely to result in death [risk ratio 16·69, 95% confidence interval (CI) 10·28–27·07 and 13·98, 95% CI 7·74–25·27, respectively]. When controlling for age and the presence of other clinical syndromes the odds of death in patients manifesting specific severe CA-MRSA syndromes was highest in those with pneumonia (odds ratio 11·34). Possible risk factors for severe CA-MRSA SSTI and pneumonia included the draining of lesions without medical assistance and an antecedent influenza-like illness.
Lessons from a large outbreak of Escherichia coli O157[ratio ]H7 infections: insights into the infectious dose and method of widespread contamination of hamburger patties
- J. TUTTLE, T. GOMEZ, M. P. DOYLE, J. G. WELLS, T. ZHAO, R. V. TAUXE, P. M. GRIFFIN
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- Epidemiology & Infection / Volume 122 / Issue 2 / April 1999
- Published online by Cambridge University Press:
- 01 April 1999, pp. 185-192
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Between November 1992 and February 1993, a large outbreak of Escherichia coli O157[ratio ]H7 infections occurred in the western USA and was associated with eating ground beef patties at restaurants of one fast-food chain. Restaurants that were epidemiologically linked with cases served patties produced on two consecutive dates; cultures of recalled ground beef patties produced on those dates yielded E. coli O157[ratio ]H7 strains indistinguishable from those isolated from patients, confirming the vehicle of illness. Seventy-six ground beef patty samples were cultured quantitatively for E. coli O157[ratio ]H7. The median most probable number of organisms was 1·5 per gram (range, <0·3–15) or 67·5 organisms per patty (range, <13·5–675). Correlation of the presence of E. coli O157[ratio ]H7 with other bacterial indicators yielded a significant association between coliform count and the presence of E. coli O157[ratio ]H7 (P=0·04). A meat traceback to investigate possible sources of contamination revealed cattle were probably initially colonized with E. coli O157[ratio ]H7, and that their slaughter caused surface contamination of meat, which once combined with meat from other sources, resulted in a large number of contaminated ground beef patties. Microbiological testing of meat from lots consumed by persons who became ill was suggestive of an infectious dose for E. coli O157[ratio ]H7 of fewer than 700 organisms. These findings present a strong argument for enforcing zero tolerance for this organism in processed food and for markedly decreasing contamination of raw ground beef. Process controls that incorporate microbiological testing of meat may assist these efforts.
Comments on the effects of solution precursor characteristics and thermal processing conditions on the crystallization behavior of sol-gel derived lead zirconate titanate thin films
- R. W. Schwartz, J. A. Voigt, B. A. Tuttle, D. A. Payne, T. L. Reichert, R. S. DaSalla
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- Journal of Materials Research / Volume 12 / Issue 2 / February 1997
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- 31 January 2011, pp. 444-456
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- February 1997
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Lead zirconate titanate (PZT 40/60) thin films were fabricated on electroded silicon wafers using chemical solution deposition. Two different chelating agents, acetic acid and acetylacetone, were used in the synthesis of the precursor solutions. The microstructure of the acetylacetone-derived film was characterized by nucleation at the platinum electrode and a columnar growth morphology (˜100−200 nm lateral grain size). In contrast, the acetic acid-derived film was characterized by both columnar grains nucleated at the electrode, and larger (˜1 μm) grains nucleated at the surface of the film. Using Fourier transform infrared (FTIR) diffuse reflectance spectroscopy, we also noted that the pyrolysis behavior of the films was dependent on the chelating agent employed. The acetylacetone-derived films, which displayed only one nucleation event, were also characterized by a higher pyrolysis temperature than the acetic acid-derived films. Previously, microstructural differences of this nature were attributed to variations in “precursor structure.” In this paper, we discuss an alternative mechanism for the observed microstructural variations in films prepared from different solution precursors. In the model proposed, we discuss how changes in film pyrolysis temperature result in a change in film crystallization temperature, and hence, a change in the effective driving force for crystallization. We show how the change in crystallization driving force is expected to impact the thin film microstructure due to the accompanying variations that occur in the barrier heights for interface (lower electrode) and surface nucleation. A standard approach to nucleation in glasses is used as the basis of the proposed model. Finally, we also discuss how the model can be used to understand the observed effects of heating rate and thickness on the microstructure of solution-derived thin films.
Chemically Prepared Lead Magnesium Niobate Dielectrics
- B. A. Tuttle, J. A. Voigt, D. L. Sipola, W. R. Olson, D. M. Goy
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- MRS Online Proceedings Library Archive / Volume 495 / 1997
- Published online by Cambridge University Press:
- 10 February 2011, 185
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- 1997
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A chemical solution powder synthesis technique has been developed that produces fine, uniform powders of lead magnesium niobate (PMN) with 60 to 80 nm crystallite size. The synthesis technique was based on the dissolution of lead acetate and alkoxide precursors in acetic acid followed by precipitation with oxalic acid/propanol solutions. Lead magnesium niobate ceramics fabricated from these chemically derived powders had smaller, more uniform grain size and higher dielectric constants than ceramics fabricated from mixed oxide powders that were processed under similar thermal conditions. Chem-prep PMN dielectrics with peak dielectric constants greater than 22,000 and polarizations in excess of 29 μC/cm2 were obtained for 1100°C firing treatments. Substantial decreases in dielectric constant and polarization were measured for chemically prepared PMN ceramics fired at lower temperatures, consistent with previous work on mixed oxide materials.
Voltage Shifts and Defect-Dipoles in Ferroelectric Capacitors
- W. L. Warren, G. E. Pike, D. Dimos, K. Vanheusden, H.N. Al-Shareef, B. A. Tuttle, R. Ramesh, J. T. Evans, Jr.
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- MRS Online Proceedings Library Archive / Volume 433 / 1996
- Published online by Cambridge University Press:
- 10 February 2011, 257
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- 1996
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We review the processes and mechanisms by which voltage offsets occur in the hysteresis loop of ferroelectric materials. Simply stated, voltage shifts arise from nearinterfacial charge trapping in the ferroelectric. We show that the impetus behind voltage shifts in ferroelectric capacitors is the net polarization, with the net polarization being determined by the perovskite and the aligned defect-dipole components. Some common defect-dipoles in the PZT system are lead vacancy-oxygen vacancy complexes. One way to change the net polarization in the ferroelectric is to subject the PZT capacitor to a dc bias at elevated temperature; this process is spectroscopically shown to align defect-dipoles along the direction of the applied electric field. The alignment of defect-dipoles can strongly impact several material properties. One such impact is that it can lead to enhanced voltage shifts (imprint). It is proposed that the net polarization determines the spatial location of the asymmetrically trapped charge that are the cause for the voltage shifts. An enhanced polarization at one electrode interface can lead to larger voltage shifts since it lowers the electrostatic potential well for electron trapping, i.e., more electron trapping can occur. Defect-dipole alignment is also shown to increase the UV sensitivity of the ferroelectric.
Effects of the Concentration of Ga on Junction Formation in Thin-film ZnO/CdS/CuInXGal-XSe2 /Mo Photovoltaic Devices
- R. J. Matson, M. A. Contreras, J. R. Tuttle, A. B. Swartzlander, P. A. Parilla, R. Noufi
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- Journal:
- MRS Online Proceedings Library Archive / Volume 426 / 1996
- Published online by Cambridge University Press:
- 10 February 2011, 183
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- 1996
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Charge-collection microscopy (CCM)—commonly known as electron-beam-induced current [EBIC] microscopy—in a scanning electron microscope (SEM) was used to obtain charge-collection efficiency profiles of cleaved thin-film ZnO/CdS/CuInXGal-XSe2/Mo photovoltaic devices on glass substrates, with x varied between 0 and 100%. We observed considerable variation in the EBIC peak position, the uniformity (between and within devices), and overall charge-collection profile of the junction as a function of Ga concentration. Whereas using only CuInSe2 (CIS) absorber material results in a rather wide and buried junction in the CIS, the systematic addition of Ga to the p-CuInSe2 matrix affects the conductivity type of the material, thereby creating an increasingly abrupt, uniform, and shallow junction near the heteroface. Although the substitution of Ga for In improves overall device performance up to ∼ X=25% and the Voc continues to improve, the Jsc, FF, and device efficiency degrade with additional Ga.
The Performance of Cu(In, Ga)Se2-Based Solar Cells in Conventional and Concentrator Applications
- J. R. Tuttle, J. S. Ward, A. Duda, T. A. Berens, M. A. Contreras, K. R. Ramanathan, A. L. Tennant, J. Keane, E. D. Cole, K. Emery, R. Noufi
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- MRS Online Proceedings Library Archive / Volume 426 / 1996
- Published online by Cambridge University Press:
- 10 February 2011, 143
- Print publication:
- 1996
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Cu(In, Ga)Se2 (CIGS) solar cells are under investigation for 1-sun and concentrator applications. Design criteria are examined and reveal that only grid design modifications are required. In the special case where cell width dimensions are 4–5 cm, an interdigitated design removes the back contact as a loss mechanism. Processing issues relating to the intrinsic ZnO layer are critical to optimal and reproducible cell performance. 1-sun and 20 sun performance of 17.7% are reported for different cells. The latter represents a 2.9% absolute improvement over the 1-sun control measurement. 20% performance is therefore a realistic goal. CIGS-based cells represent a viable concentrator technology.
A Microstructural Comparison of Cu(In,Ga)Se2 Thin Films Grown from CuxSe and (In,Ga)2Se3 Precursors
- Andrew M Gabor, J. R. Tuttle, D. S. Albin, R. Matson, A. Franz, D. W. Niles, M. A. Contreras, A. M. Hermann, R. Noufi
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- Journal:
- MRS Online Proceedings Library Archive / Volume 343 / 1994
- Published online by Cambridge University Press:
- 15 February 2011, 143
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- 1994
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We fabricated CulnSe2 and Cu(In,Ga)Se2 thin films by two different pathways using physical vapor deposition. In the first we formed a Cu-Se precursor and then reacted it with a flux of (In,Ga) + Se. These films had large grains but were too rough for optimal device performance. In the other pathway, we first formed a smooth precursor of (In,Ga)2Se3 and then exposed it to a flux of Cu+Se. We overshot the optimal film composition to allow recrystallization of the film by a secondary CuxSe phase. We then consumed the excess CuxSe in a third stage deposition of (In,Ga) + Se. The recrystallization step increased the grain sizes, and the resulting films remained smooth. Photovoltaic solar cells made from these films have produced the highest total-area efficiencies of any non-single-crystal, thin-film solar cell.
Microstructural Evolution of Pb(Zr,Ti)O3 Ceramics Using Electron Paramagnetic Resonance
- W. L. Warren, B. A. Tuttle, R. W. Schwartz, W. F. Hammetter, D. C. Goodnow, J. T. Evans, Jr., J. A. Bullington
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- Journal:
- MRS Online Proceedings Library Archive / Volume 310 / 1993
- Published online by Cambridge University Press:
- 21 February 2011, 3
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- 1993
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Using electron paramagnetic resonance (EPR) we have followed the microstructural evolution with temperature of lead zirconate titanate (PZT) ceramics from the amorphous to the perovskite phase. A number of paramagnetic point defects were identified (Carbon, Pb+3, and Ti+3) while traversing the evolution of these ceramics during various heat treatments both before and after optical illumination. Perhaps the most important finding is that the Pb+3 and Ti+3 centers can only be optically created in the perovskite materials, thereby, showing that they are not associated with the amorphous or the pyrochlore phases. It is also found that EPR signals attributed to carbon radicals are present in fairly high concentrations (4 × 1017/cm3) if the solution chemistry derived PZT materials are annealed in an oxygen deficient ambient (0.1% O2) at 650°C.
The Effect of Copper Vacancies on the Optical Bowing of Chalcopyrite Cu(In,Ga)Se2 Alloys
- D. S. Albin, J. J. Carapella, J. R. Tuttle, R. Noufi
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- Journal:
- MRS Online Proceedings Library Archive / Volume 228 / 1991
- Published online by Cambridge University Press:
- 21 February 2011, 267
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- 1991
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The optical bowing behavior of polycrystalline thin film Culn1-yGaySe2 alloys is dependent upon the Cu stoichiometry. The variation in optical band gap, Eg, for alloys in which Cu is near stoichiometric (25 at.%) is parabolic and follows the relationship: Eg(y) = 1.011 + 0.421 y + 0.244 y2 (eV), where y is the alloy parameter, [at.% Ga] / [at.%Ga + at.%In]. Contrary to this, films with Cu-poor stoichiometries (∼19 at.% Cu) exhibit little alloy bowing: Eg(y) = 1.01 + 0.733 y - 0.046 y2 (eV). The increase in Eg with Cu deficiency appears to be the result of both a structural effect associated with tetragonal lattice shrinkage, ΔV = Vstoichiometric - VCu-poor (resulting from the presence of Cu vacancies) and a chemical effect, possibly associated with a counterbalance between p-d repulsion and anion displacement effects.