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SOIL CARBON STOCKS NOT LINKED TO ABOVEGROUND LITTER INPUT AND CHEMISTRY OF OLD-GROWTH FOREST AND ADJACENT PRAIRIE
- Karis J McFarlane, Stefania Mambelli, Rachel C Porras, Daniel B Wiedemeier, Michael W I Schmidt, Todd E Dawson, Margaret S Torn
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- Journal:
- Radiocarbon , First View
- Published online by Cambridge University Press:
- 13 February 2024, pp. 1-18
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The long-standing assumption that aboveground plant litter inputs have a substantial influence on soil organic carbon storage (SOC) and dynamics has been challenged by a new paradigm for SOC formation and persistence. We tested the importance of plant litter chemistry on SOC storage, distribution, composition, and age by comparing two highly contrasting ecosystems: an old-growth coast redwood (Sequoia sempervirens) forest, with highly aromatic litter, and an adjacent coastal prairie, with more easily decomposed litter. We hypothesized that if plant litter chemistry was the primary driver, redwood would store more and older SOC that was less microbially processed than prairie. Total soil carbon stocks to 110 cm depth were higher in prairie (35 kg C m−2) than redwood (28 kg C m−2). Radiocarbon values indicated shorter SOC residence times in redwood than prairie throughout the profile. Higher amounts of pyrogenic carbon and a higher degree of microbial processing of SOC appear to be instrumental for soil carbon storage and persistence in prairie, while differences in fine-root carbon inputs likely contribute to younger SOC in redwood. We conclude that at these sites fire residues, root inputs, and soil properties influence soil carbon dynamics to a greater degree than the properties of aboveground litter.
Predicting relapse or recurrence of depression: systematic review of prognostic models
- Andrew S. Moriarty, Nicholas Meader, Kym I. E. Snell, Richard D. Riley, Lewis W. Paton, Sarah Dawson, Jessica Hendon, Carolyn A. Chew-Graham, Simon Gilbody, Rachel Churchill, Robert S. Phillips, Shehzad Ali, Dean McMillan
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- Journal:
- The British Journal of Psychiatry / Volume 221 / Issue 2 / August 2022
- Published online by Cambridge University Press:
- 11 January 2022, pp. 448-458
- Print publication:
- August 2022
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Background
Relapse and recurrence of depression are common, contributing to the overall burden of depression globally. Accurate prediction of relapse or recurrence while patients are well would allow the identification of high-risk individuals and may effectively guide the allocation of interventions to prevent relapse and recurrence.
AimsTo review prognostic models developed to predict the risk of relapse, recurrence, sustained remission, or recovery in adults with remitted major depressive disorder.
MethodWe searched the Cochrane Library (current issue); Ovid MEDLINE (1946 onwards); Ovid Embase (1980 onwards); Ovid PsycINFO (1806 onwards); and Web of Science (1900 onwards) up to May 2021. We included development and external validation studies of multivariable prognostic models. We assessed risk of bias of included studies using the Prediction model risk of bias assessment tool (PROBAST).
ResultsWe identified 12 eligible prognostic model studies (11 unique prognostic models): 8 model development-only studies, 3 model development and external validation studies and 1 external validation-only study. Multiple estimates of performance measures were not available and meta-analysis was therefore not necessary. Eleven out of the 12 included studies were assessed as being at high overall risk of bias and none examined clinical utility.
ConclusionsDue to high risk of bias of the included studies, poor predictive performance and limited external validation of the models identified, presently available clinical prediction models for relapse and recurrence of depression are not yet sufficiently developed for deploying in clinical settings. There is a need for improved prognosis research in this clinical area and future studies should conform to best practice methodological and reporting guidelines.
Compounding and complementary carnivores: Australian bird species eaten by the introduced European red fox Vulpes vulpes and domestic cat Felis catus
- JOHN C.Z. WOINARSKI, ALYSON M. STOBO-WILSON, HEATHER M. CRAWFORD, STUART J. DAWSON, CHRIS R. DICKMAN, TIM S. DOHERTY, PATRICIA A. FLEMING, STEPHEN T. GARNETT, MATTHEW N. GENTLE, SARAH M. LEGGE, THOMAS M. NEWSOME, RUSSELL PALMER, MATTHEW W. REES, EUAN G. RITCHIE, JAMES SPEED, JOHN-MICHAEL STUART, EILYSH THOMPSON, JEFF TURPIN, BRETT P. MURPHY
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- Journal:
- Bird Conservation International / Volume 32 / Issue 3 / September 2022
- Published online by Cambridge University Press:
- 02 December 2021, pp. 506-522
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Two introduced carnivores, the European red fox Vulpes vulpes and domestic cat Felis catus, have had extensive impacts on Australian biodiversity. In this study, we collate information on consumption of Australian birds by the fox, paralleling a recent study reporting on birds consumed by cats. We found records of consumption by foxes on 128 native bird species (18% of the non-vagrant bird fauna and 25% of those species within the fox’s range), a smaller tally than for cats (343 species, including 297 within the fox’s Australian range, a subset of that of the cat). Most (81%) bird species eaten by foxes are also eaten by cats, suggesting that predation impacts are compounded. As with consumption by cats, birds that nest or forage on the ground are most likely to be consumed by foxes. However, there is also some partitioning, with records of consumption by foxes but not cats for 25 bird species, indicating that impacts of the two predators may also be complementary. Bird species ≥3.4 kg were more likely to be eaten by foxes, and those <3.4 kg by cats. Our compilation provides an inventory and describes characteristics of Australian bird species known to be consumed by foxes, but we acknowledge that records of predation do not imply population-level impacts. Nonetheless, there is sufficient information from other studies to demonstrate that fox predation has significant impacts on the population viability of some Australian birds, especially larger birds, and those that nest or forage on the ground.
Comparison of settlement-era vegetation reconstructions for STEPPS and REVEALS pollen–vegetation models in the northeastern United States
- Mathias Trachsel, Andria Dawson, Christopher J. Paciorek, John W. Williams, Jason S. McLachlan, Charles V. Cogbill, David R. Foster, Simon J. Goring, Stephen T. Jackson, W. Wyatt Oswald, Bryan N. Shuman
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- Journal:
- Quaternary Research / Volume 95 / May 2020
- Published online by Cambridge University Press:
- 07 April 2020, pp. 23-42
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Reconstructions of prehistoric vegetation composition help establish natural baselines, variability, and trajectories of forest dynamics before and during the emergence of intensive anthropogenic land use. Pollen–vegetation models (PVMs) enable such reconstructions from fossil pollen assemblages using process-based representations of taxon-specific pollen production and dispersal. However, several PVMs and variants now exist, and the sensitivity of vegetation inferences to PVM selection, variant, and calibration domain is poorly understood. Here, we compare the reconstructions, parameter estimates, and structure of a Bayesian hierarchical PVM, STEPPS, both to observations and to REVEALS, a widely used PVM, for the pre–Euro-American settlement-era vegetation in the northeastern United States (NEUS). We also compare NEUS-based STEPPS parameter estimates to those for the upper midwestern United States (UMW). Both PVMs predict the observed macroscale patterns of vegetation composition in the NEUS; however, reconstructions of minor taxa are less accurate and predictions for some taxa differ between PVMs. These differences can be attributed to intermodel differences in structure and parameter estimates. Estimates of pollen productivity from STEPPS broadly agree with estimates produced for use in REVEALS, while comparison between pollen dispersal parameter estimates shows no significant relationship. STEPPS parameter estimates are similar between the UMW and NEUS, suggesting that STEPPS parameter estimates are transferable between floristically similar regions and scales.
Chevkinite-group minerals from salic volcanic rocks of the East African Rift
- R. Macdonald, A. S. Marshall, J. B. Dawson, R. W. Hinton, P. G. Hill
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- Journal:
- Mineralogical Magazine / Volume 66 / Issue 2 / April 2002
- Published online by Cambridge University Press:
- 05 July 2018, pp. 287-299
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Electron microprobe analyses are presented of chevkinite-group minerals occurring as microphenocrysts in peralkaline rhyolites of the Greater Olkaria Volcanic Complex (Kenya) and as a groundmass phase in a peralkaline quartz trachyte lava from the Tarosero volcano (Tanzania), both in the East African Rift Valley. Their compositions conform closely to the formula: (REE, Ca, Th)4 Fe2+ (Fe2+, Al, Ti, Zr, Nb)2 Ti2 (Si4O22). Compared to published analyses of chevkinite-group minerals, the Olkaria phases are relatively enriched in Nb and the LREE; the Tarosero phase is more calcic and relatively Zr- and Nb-rich. The main substitution in the A site at Olkaria is Ca ⇌ Ce. The overall charge-balancing substitution seems to be (McDowell, 1979):
Phenocryst/glass ratios are presented for Nb, REE, Sr, Th, U and Y in two, and Ba, Zr and Hf in one, Kenyan samples. Partition coefficients are lower in the more peralkaline rock, with the exception of Sr, which is higher. The lower values are consistent with a lower degree of polymerization of more peralkaline melts. The higher Sr value may be a function of Sr partitioning into phenocryst phases coexisting with chevkinite.
The effects of breed, month of parturition and sex of progeny on beef cow fertility using calving interval as a measure
- F. M. Titterington, F. O. Lively, S. Dawson, A. W. Gordon, S. J. Morrison
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- Journal:
- Advances in Animal Biosciences / Volume 8 / Issue s1 / October 2017
- Published online by Cambridge University Press:
- 03 October 2017, pp. s67-s71
- Print publication:
- October 2017
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This study aimed to evaluate levels of beef cow fertility using calving interval (CI; measured in days) as a measure, and investigate the effects of breed, season, year and progeny gender on CI. The CI data included 273 764 records collected between 1997 and 2012 and included the seven most common breeds (and their crosses) in Northern Ireland (Charolais, Limousin, Belgian Blue, Simmental, Blonde d’Aquitaine, Aberdeen Angus and Hereford), accounting for 94.1% of beef dams recorded. Mean CI for all cows was 395 days, 30 days longer than the optimum 365 days. Charolais and Belgian Blue dams had the longest CI (P<0.05). Cows older than 144 months had a longer CI (P<0.05) compared with cows younger than 144 months. Charolais sires had a shorter subsequent CI of 392 days (P<0.05) compared with the other breeds. Cows calving in June had the shortest subsequent CI (376 days; P<0.05), whereas cows calving in November had the longest subsequent CI (410 days). Progeny gender did not significantly affect CI. This study establishes the level of beef cow fertility using CI as a measure in Northern Ireland is sub optimal and there are opportunities for improvement. Factors identified as influencing CI included dam breed, sire breed and month of parturition. This knowledge can be used to direct breeding programmes and inform knowledge transfer protocol to improve sustainability of beef production.
Intensity ratios for XDR/PDR identification
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- C.-E. Green, M. R. Cunningham, J. A. Green, J. R. Dawson, P. A. Jones, Á. R. López-Sánchez, L. Verdes-Montenegro, C. Henkel, W. A. Baan, S. Martín
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- Journal:
- Proceedings of the International Astronomical Union / Volume 11 / Issue S315 / August 2015
- Published online by Cambridge University Press:
- 12 September 2016, E30
- Print publication:
- August 2015
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The intensity ratios of HCO+/HCN and HNC/HCN (1-0) reveal the relative influence of star formation and active galactic nuclei (AGN) or black holes on the circum-nuclear gas of a galaxy, allowing the identification of X-ray dominated regions (XDRs) and Photon-dominated regions (PDRs). It is not always clear in the literature how this intensity ratio calculation has been, or should be performed. This paper discusses ratio calculation methods for interferometric data.
GASKAP—The Galactic ASKAP Survey
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- John M. Dickey, Naomi McClure-Griffiths, Steven J. Gibson, José F. Gómez, Hiroshi Imai, Paul Jones, Snežana Stanimirović, Jacco Th. Van Loon, Andrew Walsh, A. Alberdi, G. Anglada, L. Uscanga, H. Arce, M. Bailey, A. Begum, B. Wakker, N. Ben Bekhti, P. Kalberla, B. Winkel, K. Bekki, B.-Q. For, L. Staveley-Smith, T. Westmeier, M. Burton, M. Cunningham, J. Dawson, S. Ellingsen, P. Diamond, J. A. Green, A. S. Hill, B. Koribalski, D. McConnell, J. Rathborne, M. Voronkov, K. A. Douglas, J. English, H. Alyson Ford, F. J. Lockman, T. Foster, Y. Gomez, A. Green, J. Bland-Hawthorn, S. Gulyaev, M. Hoare, G. Joncas, J.-H. Kang, C. R. Kerton, B.-C. Koo, D. Leahy, N. Lo, V. Migenes, J. Nakashima, Y. Zhang, D. Nidever, J. E. G. Peek, D. Tafoya, W. Tian, D. Wu
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- Journal:
- Publications of the Astronomical Society of Australia / Volume 30 / 2013
- Published online by Cambridge University Press:
- 24 January 2013, e003
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A survey of the Milky Way disk and the Magellanic System at the wavelengths of the 21-cm atomic hydrogen (H i) line and three 18-cm lines of the OH molecule will be carried out with the Australian Square Kilometre Array Pathfinder telescope. The survey will study the distribution of H i emission and absorption with unprecedented angular and velocity resolution, as well as molecular line thermal emission, absorption, and maser lines. The area to be covered includes the Galactic plane (|b| < 10°) at all declinations south of δ = +40°, spanning longitudes 167° through 360°to 79° at b = 0°, plus the entire area of the Magellanic Stream and Clouds, a total of 13 020 deg2. The brightness temperature sensitivity will be very good, typically σT≃ 1 K at resolution 30 arcsec and 1 km s−1. The survey has a wide spectrum of scientific goals, from studies of galaxy evolution to star formation, with particular contributions to understanding stellar wind kinematics, the thermal phases of the interstellar medium, the interaction between gas in the disk and halo, and the dynamical and thermal states of gas at various positions along the Magellanic Stream.
The epidemiology of published norovirus outbreaks: a review of risk factors associated with attack rate and genogroup
- J. E. MATTHEWS, B. W. DICKEY, R. D. MILLER, J. R. FELZER, B. P. DAWSON, A. S. LEE, J. J. ROCKS, J. KIEL, J. S. MONTES, C. L. MOE, J. N. S. EISENBERG, J. S. LEON
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- Journal:
- Epidemiology & Infection / Volume 140 / Issue 7 / July 2012
- Published online by Cambridge University Press:
- 27 March 2012, pp. 1161-1172
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The purpose of this study was to examine global epidemiological trends in human norovirus (NoV) outbreaks by transmission route and setting, and describe relationships between these characteristics, viral attack rates, and the occurrence of genogroup I (GI) or genogroup II (GII) strains in outbreaks. We analysed data from 902 reverse transcriptase–polymerase chain reaction-confirmed, human NoV outbreaks abstracted from a systematic review of articles published from 1993 to 2011 and indexed under the terms ‘norovirus’ and ‘outbreak’. Multivariate regression analyses demonstrated that foodservice and winter outbreaks were significantly associated with higher attack rates. Foodborne and waterborne outbreaks were associated with multiple strains (GI+GII). Waterborne outbreaks were significantly associated with GI strains, while healthcare-related and winter outbreaks were associated with GII strains. These results identify important trends for epidemic NoV detection, prevention, and control.
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. Kirk-Duggan, Clifton Kirkpatrick, Leonid Kishkovsky, Nadieszda Kizenko, Jeffrey Klaiber, Hans-Josef Klauck, Sidney Knight, Samuel Kobia, Robert Kolb, Karla Ann Koll, Heikki Kotila, Donald Kraybill, Philip D. W. Krey, Yves Krumenacker, Jeffrey Kah-Jin Kuan, Simanga R. Kumalo, Peter Kuzmic, Simon Shui-Man Kwan, Kwok Pui-lan, André LaCocque, Stephen E. Lahey, John Tsz Pang Lai, Emiel Lamberts, Armando Lampe, Craig Lampe, Beverly J. Lanzetta, Eve LaPlante, Lizette Larson-Miller, Ariel Bybee Laughton, Leonard Lawlor, Bentley Layton, Robin A. Leaver, Karen Lebacqz, Archie Chi Chung Lee, Marilyn J. Legge, Hervé LeGrand, D. L. LeMahieu, Raymond Lemieux, Bill J. Leonard, Ellen M. Leonard, Outi Leppä, Jean Lesaulnier, Nantawan Boonprasat Lewis, Henrietta Leyser, Alexei Lidov, Bernard Lightman, Paul Chang-Ha Lim, Carter Lindberg, Mark R. Lindsay, James R. Linville, James C. Livingston, Ann Loades, David Loades, Jean-Claude Loba-Mkole, Lo Lung Kwong, Wati Longchar, Eleazar López, David W. 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. Douglas Meeks, Monica Jyotsna Melanchthon, Ilie Melniciuc-Puica, Everett Mendoza, Raymond A. Mentzer, William W. Menzies, Ina Merdjanova, Franziska Metzger, Constant J. Mews, Marvin Meyer, Carol Meyers, Vasile Mihoc, Gunner Bjerg Mikkelsen, Maria Inêz de Castro Millen, Clyde Lee Miller, Bonnie J. Miller-McLemore, Alexander Mirkovic, Paul Misner, Nozomu Miyahira, R. W. L. Moberly, Gerald Moede, Aloo Osotsi Mojola, Sunanda Mongia, Rebeca Montemayor, James Moore, Roger E. Moore, Craig E. Morrison O.Carm, Jeffry H. Morrison, Keith Morrison, Wilson J. Moses, Tefetso Henry Mothibe, Mokgethi Motlhabi, Fulata Moyo, Henry Mugabe, Jesse Ndwiga Kanyua Mugambi, Peggy Mulambya-Kabonde, Robert Bruce Mullin, Pamela Mullins Reaves, Saskia Murk Jansen, Heleen L. Murre-Van den Berg, Augustine Musopole, Isaac M. T. Mwase, Philomena Mwaura, Cecilia Nahnfeldt, Anne Nasimiyu Wasike, Carmiña Navia Velasco, Thulani Ndlazi, Alexander Negrov, James B. Nelson, David G. Newcombe, Carol Newsom, Helen J. Nicholson, George W. E. Nickelsburg, Tatyana Nikolskaya, Damayanthi M. A. Niles, Bertil Nilsson, Nyambura Njoroge, Fidelis Nkomazana, Mary Beth Norton, Christian Nottmeier, Sonene Nyawo, Anthère Nzabatsinda, Edward T. Oakes, Gerald O'Collins, Daniel O'Connell, David W. Odell-Scott, Mercy Amba Oduyoye, Kathleen O'Grady, Oyeronke Olajubu, Thomas O'Loughlin, Dennis T. Olson, J. Steven O'Malley, Cephas N. Omenyo, Muriel Orevillo-Montenegro, César Augusto Ornellas Ramos, Agbonkhianmeghe E. Orobator, Kenan B. Osborne, Carolyn Osiek, Javier Otaola Montagne, Douglas F. Ottati, Anna May Say Pa, Irina Paert, Jerry G. Pankhurst, Aristotle Papanikolaou, Samuele F. Pardini, Stefano Parenti, Peter Paris, Sung Bae Park, Cristián G. Parker, Raquel Pastor, Joseph Pathrapankal, Daniel Patte, W. Brown Patterson, Clive Pearson, Keith F. Pecklers, Nancy Cardoso Pereira, David Horace Perkins, Pheme Perkins, Edward N. Peters, Rebecca Todd Peters, Bishop Yeznik Petrossian, Raymond Pfister, Peter C. 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. Rubenstein, Rosemary Radford Ruether, Markku Ruotsila, John E. Rybolt, Risto Saarinen, John Saillant, Juan Sanchez, Wagner Lopes Sanchez, Hugo N. Santos, Gerhard Sauter, Gloria L. Schaab, Sandra M. Schneiders, Quentin J. Schultze, Fernando F. Segovia, Turid Karlsen Seim, Carsten Selch Jensen, Alan P. F. Sell, Frank C. Senn, Kent Davis Sensenig, Damían Setton, Bal Krishna Sharma, Carolyn J. Sharp, Thomas Sheehan, N. Gerald Shenk, Christian Sheppard, Charles Sherlock, Tabona Shoko, Walter B. Shurden, Marguerite Shuster, B. Mark Sietsema, Batara Sihombing, Neil Silberman, Clodomiro Siller, Samuel Silva-Gotay, Heikki Silvet, John K. Simmons, Hagith Sivan, James C. Skedros, Abraham Smith, Ashley A. Smith, Ted A. Smith, Daud Soesilo, Pia Søltoft, Choan-Seng (C. S.) Song, Kathryn Spink, Bryan Spinks, Eric O. Springsted, Nicolas Standaert, Brian Stanley, Glen H. Stassen, Karel Steenbrink, Stephen J. Stein, Andrea Sterk, Gregory E. Sterling, Columba Stewart, Jacques Stewart, Robert B. 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. Van Bavel, Steven Vanderputten, Peter Van der Veer, Huub Van de Sandt, Louis Van Tongeren, Luke A. Veronis, Noel Villalba, Ramón Vinke, Tim Vivian, David Voas, Elena Volkova, Katharina von Kellenbach, Elina Vuola, Timothy Wadkins, Elaine M. Wainwright, Randi Jones Walker, Dewey D. Wallace, Jerry Walls, Michael J. Walsh, Philip Walters, Janet Walton, Jonathan L. Walton, Wang Xiaochao, Patricia A. Ward, David Harrington Watt, Herold D. Weiss, Laurence L. Welborn, Sharon D. Welch, Timothy Wengert, Traci C. West, Merold Westphal, David Wetherell, Barbara Wheeler, Carolinne White, Jean-Paul Wiest, Frans Wijsen, Terry L. Wilder, Felix Wilfred, Rebecca Wilkin, Daniel H. Williams, D. Newell Williams, Michael A. Williams, Vincent L. Wimbush, Gabriele Winkler, Anders Winroth, Lauri Emílio Wirth, James A. Wiseman, Ebba Witt-Brattström, Teofil Wojciechowski, John Wolffe, Kenman L. Wong, Wong Wai Ching, Linda Woodhead, Wendy M. Wright, Rose Wu, Keith E. Yandell, Gale A. 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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The recovery of tryptophan A auxotrophs at high frequency in a strain of Salmonella typhimurium
- S. Riyasaty, G. W. P. Dawson
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- Journal:
- Genetical Research / Volume 10 / Issue 2 / October 1967
- Published online by Cambridge University Press:
- 14 April 2009, pp. 127-134
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1. Auxotrophs were sought in a slow-growing reversion of the tryA47 strain of S. typhimurium. This reversion differs from tryA47 by a genetic change that is inseparable from the 47 site and has been designated 47S. Out of thirty-nine auxotrophs that derived from independent mutations, twenty-two grew on minimal medium supplemented with anthranilic acid. Eight of these auxotrophs were examined and each was shown to have the 47S site unchanged and to carry a further mutation in the tryA gene. These further mutations were shown to be at different sites in different auxotrophs.
2. Auxotrophs were sought in the wild-type LT-2 strain. None out of thirty-six were mutant in the tryA gene.
3. The 47S site in tryA47S was replaced by 47+ transduced from wild-type LT-2. Auxotrophs were sought in this strain and only one out of nineteen was mutant in the tryA gene.
4. Auxotrophs were sought in a wild-type reversion of tryA47. Out of twenty-six none were mutant in the tryA gene.
5. The 47+ site in wild-type LT-2 was replaced by 47S transduced from tryA47S. Auxotrophs were sought in this strain and twenty-two out of fifty-five were mutant in the tryA gene.
6. We conclude that tryA auxotrophs are only recovered at a high frequency when the 47S site is present in the tryA gene.
7. In strains with the 47S site in the tryA gene the frequency of auxotrophs that will grow on minimal medium supplemented with indole but not on minimal medium supplemented with anthranilic acid is appreciably higher than in those strains without the 47S site in the tryA gene. These auxotrophs are mutant in genes that are in the same operon as tryA.
A genetic study of primary and secondary reversions of some tryptophanA auxotrophs of Salmonella typhimurium
- S. Riyasaty, G. W. P. Dawson
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- Journal:
- Genetical Research / Volume 9 / Issue 3 / June 1967
- Published online by Cambridge University Press:
- 14 April 2009, pp. 269-282
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1. The linkage order of four tryA mutants of S. typhimurium, and cysB-12, is:
Attempts to plot the position of tryA-50 were unsuccessful.
2. Some of the reversions of tryA-8, tryA-47, tryA-56 and tryA-50 were analysed genetically; tryA-52 does not revert. All four auxotrophs gave reversions that were phenotypically and genetically indistinguishable from that expected by back-mutation of the original mutant site.
3. Both tryA-8 and tryA-50 produced reversions that grew as wild-type but were due to unlinked suppressor mutations. Some of these were super-suppressors in that they suppressed both tryA-8 and tryB-4; others suppressed many site mutants in the tryA gene but did not suppress tryB-4.
4. All the slow-growing reversions of tryA-8, tryA-50 and tryA-56, and a minority of the semi-fast reversions of tryA-8, were due to unlinked suppressors.
5. All the slow-growing reversions of tryA-47, the semi-fast reversions of tryA-56 and the majority of the semi-fast reversions of tryA-8 were due to genetic changes that were inseparable, in very extensive experiments, from their original mutant site.
6. Slow-growing reversions of tryA-47 produced faster growing mutants. Some of these were due to mutation in unlinked modifying genes and in others the genetic change was within the tryA gene. Nine of the latter had the genetic change just to the left of the 47S site; in one the change was inseparable from the 47S site. None had this further change to the right of the 47S site. These further changes, in the absence of the 47S site, gave prototrophic phenotypes; they are inter-site suppressors.
Walking the dog: exploration of the contact networks between dogs in a community
- C. WESTGARTH, R. M. GASKELL, G. L. PINCHBECK, J. W. S. BRADSHAW, S. DAWSON, R. M. CHRISTLEY
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- Epidemiology & Infection / Volume 137 / Issue 8 / August 2009
- Published online by Cambridge University Press:
- 19 November 2008, pp. 1169-1178
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This study uses social network analysis to investigate potential contact among 214 dog-owning households in a UK community through their utilization of public space during walking. We identified a high level of potential contact between dog-owning households; most households walked their dogs in only a few areas but a small number visited many. Highly connected households were more likely to have multiple dogs, walk their dogs off lead, and own Working, Pastoral or some Terrier types. Similarly, most areas were only visited by a few households but a few were visited by many. Despite identification of subgroups of households and locations, we demonstrated high connectivity between dog-owning households, with minimum path lengths of two ‘steps’ (household–area–household, 74%) or four ‘steps’ (via two areas, 26%).
Contributors
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- By Claude Alain, Amy F. T. Arnsten, Lars Bäckman, Malcolm A. Binns, Sandra E. Black, S. Thomas Carmichael, Keith D. Cicerone, Maurizio Corbetta, Bruce Crosson, Jeffrey L. Cummings, Deirdre R. Dawson, Michael deRiesthal, Roger A. Dixon, Laura Eggermont, Kirk I. Erickson, Anthony Feinstein, Susan M. Fitzpatrick, Fu Qiang Gao, Douglas D. Garrett, Omar Ghaffar, Robbin Gibb, Elizabeth L. Glisky, Martha L. Glisky, Leslie J. Gonzalez Rothi, Cheryl L. Grady, Carol Greenwood, Gerri Hanten, Richard G. Hunter, Masud Husain, Narinder Kapur, Bryan Kolb, Arthur F. Kramer, Susan A. Leon, Harvey S. Levin, Brian Levine, Nadina Lincoln, Thomas W. McAllister, Edward McAuley, Bruce S. McEwen, David M. Morris, Stephen E. Nadeau, Roshan das Nair, Matthew Parrott, Jennie Ponsford, George P. Prigatano, Joel Ramirez, John M. Ringman, Ian H. Robertson, Amy D. Rodriguez, John C. Rosenbek, Bernhard Ross, Erik Scherder, Victoria Singh-Curry, Trudi Stickland, Donald T. Stuss, Edward Taub, Gary R. Turner, Harry V. Vinters, Samuel Weiss, John Whyte, Barbara A. Wilson, Gordon Winocur, J. Martin Wojtowicz
- Edited by Donald T. Stuss, University of Toronto, Gordon Winocur, University of Toronto, Ian H. Robertson, Trinity College, Dublin
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- Cognitive Neurorehabilitation
- Published online:
- 05 September 2015
- Print publication:
- 11 September 2008, pp ix-xiv
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The epidemiology of DSM-IV specific phobia in the USA: results from the National Epidemiologic Survey on Alcohol and Related Conditions
- FREDERICK S. STINSON, DEBORAH A. DAWSON, S. PATRICIA CHOU, SHARON SMITH, RISE B. GOLDSTEIN, W. JUNE RUAN, BRIDGET F. GRANT
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- Journal:
- Psychological Medicine / Volume 37 / Issue 7 / July 2007
- Published online by Cambridge University Press:
- 05 March 2007, pp. 1047-1059
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Background. There is a lack of current detailed national data on the prevalence, correlates, disability and co-morbidity of DSM-IV specific phobia (SP), the prevalence of specific objects and situations feared, and associations between impairment, treatment and co-morbidity and the number of specific situations and objects feared, among adults in the USA.
Method. The data were derived from a large (43093) representative sample of the adult population in the USA.
Results. Prevalences of 12-month and lifetime DSM-IV SP were 7·1% and 9·4% respectively. Being female, young, and low income increased risk, while being Asian or Hispanic decreased risk (p<0·05). The mean age at onset of SP was 9·7 years, the mean duration of episode was 20·1 years and only 8·0% reported treatment specifically for SP. Most specific phobias involved multiple fears, and an increasing number of fears, regardless of content, was associated with greater disability and impairment, treatment seeking and co-morbidity with other Axis I and II disorders.
Conclusions. SP is a highly prevalent, disabling and co-morbid disorder in the US adult population. The early onset of SP and the disorders most strongly associated with it highlights the need for longitudinal studies beginning in early childhood. Results suggest the existence of a generalized subtype of SP much like social phobia, which, once revealed, may lead to a classification of SP that is more etiologically and therapeutically meaningful.
Prevalence, correlates, co-morbidity, and comparative disability of DSM-IV generalized anxiety disorder in the USA: results from the National Epidemiologic Survey on Alcohol and Related Conditions
- BRIDGET F. GRANT, DEBORAH S. HASIN, FREDERICK S. STINSON, DEBORAH A. DAWSON, W. JUNE RUAN, RISË B. GOLDSTEIN, SHARON M. SMITH, TULSHI D. SAHA, BOJI HUANG
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- Journal:
- Psychological Medicine / Volume 35 / Issue 12 / December 2005
- Published online by Cambridge University Press:
- 05 October 2005, pp. 1747-1759
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Background. This study addressed the prevalences, correlates, co-morbidity and disability of DSM-IV generalized anxiety disorder (GAD) and other psychiatric disorders in a large national survey of the general population, the National Institute on Alcohol Abuse and Alcoholism's (NIAAA) National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). The study presents nationally representative data, for the first time, on prevalence, correlates, co-morbidity, and comparative disability of DSM-IV GAD.
Method. Data are taken from a large (n=43093) representative sample of the adult USA population.
Results. Prevalences of 12-month and lifetime GAD were 2·1% and 4·1%. Being female, middle-aged, widowed/separated/divorced, and low income increased risk, while being Asian, Hispanic, or Black decreased risk. GAD was highly co-morbid with substance use, and other anxiety, mood, and personality disorders. Co-morbidity in GAD was not substantially greater than for most other Axis I and II disorders. Disability and impairment in pure GAD were equivalent to pure mood disorders, but significantly greater than in pure substance use, and other anxiety and personality disorders. Individuals co-morbid for GAD and each mood disorder were more disabled than those with pure forms of GAD or each mood disorder. When co-morbid with GAD, nicotine dependence and other anxiety and personality disorders were not associated with increased disability over that associated with pure GAD, but GAD did show increased disability over that due to each of these disorders in pure form.
Conclusions. Associations between GAD and Axis I and II disorders were strong and significant, with variation among specific disorders. Results strongly support GAD as an independent disorder with significant impairment and disability.
The effect of slaughter weight on sensory quality of meat from Holstein-Friesian male cattle
- B. W. Moss, L. J. Farmer, R. M. Kirkland, T. W. J. Keady, D. C. Patterson, R. W. J. Steen, S. Dawson, D. J. Kilpatrick
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- Journal:
- Proceedings of the British Society of Animal Science / Volume 2005 / 2005
- Published online by Cambridge University Press:
- 23 November 2017, p. 177
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- 2005
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A considerable proportion of beef produced in the UK is a byproduct of the dairy industry. Young animals from this source are generally regarded as low in quality and meat from animals of this type is usually destined for the commodity minced beef market. The objective of the present study was to evaluate the effect of slaughter weight on sensory characteristics of meat from Holstein-Friesian bulls and steers offered a cereal-based ration.
Factors affecting the intake of grass silage by cattle and prediction of silage intake
- R. W. J. Steen, F. J. Gordon, L. E. R. Dawson, R. S. Park, C. S. Mayne, R. E. Agnew, D. J. Kilpatrick, M. G. Porter
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- Journal:
- Animal Science / Volume 66 / Issue 1 / February 1998
- Published online by Cambridge University Press:
- 02 September 2010, pp. 115-127
- Print publication:
- February 1998
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A partially balanced change-over design experiment involving 192 beef steers, which were initially 14 months old and 415 kg live weight, was carried out to determine the intakes of 136 silages from commercial farms in Northern Ireland. Each silage was offered ad libitum as the sole food to 10 animals, with eight silages offered in each of 17 periods over 2 years. A standard grass hay was offered to 16 animals in each period to enable period effects on intake to be removed. Detailed chemical and biological compositions of the silages were also determined. The ranges for pH and dry matter (DM), crude protein, ammonia-nitrogen and apparent digestible organic matter (in vivo) concentrations in the silages and silage dry DM intakes were 3·50 to 5·49 (s.d. 0·396); 155 to 413 (s.d. 43·1) g/kg; 79 to 212 (s.d. 24·4) g/kg DM; 45 to 384 (s.d. 63·2) g/kg total nitrogen; 528 to 769 (s.d. 58) g/kg DM and 4·3 to 10·9 (s.d. 1·13) kg/day respectively. Relationships between intake and individual parameters or groups of parameters have been developed using simple and multiple linear regression analysis and partial least-squares analyses. Silage intake was closely related to factors which influence the extent of digestion and rate of passage of the material through the animal, as indicated by the strong relationships (R2 of regressions = 0·28 to 0·50) with in vivo apparent digestibility and rumen degradability and the concentrations of the fibre and nitrogen factors. Intake was poorly correlated with factors such as pH, total acidity, buffering capacity and the concentrations of lactic, acetic and butyric acids (R2 of regressions = zero to 0·11). Near infrared reflectance spectrometry (NIRS) provided the best fit relationship with intake (R2 of relationship = 0·90). The results also indicate that the intake potential of silages can be directly predicted with a high degree of accuracy from the NIRS of both dried and undried samples of silage, provided the appropriate sample preparation and scanning methods are used.
Stress Release in Ion Implanted Lattice Mismatched Semiconductor Heterostructures
- G. W. Arnold, S. T. Picraux, D. R. Myers, B. L. Doyle, P. S. Peercy, R. M. Biefeld, L. R. Dawson
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- Journal:
- MRS Online Proceedings Library Archive / Volume 77 / 1986
- Published online by Cambridge University Press:
- 26 February 2011, 417
- Print publication:
- 1986
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Cantilever-beam measurements of ion-implantation induced stress in (InGa)As/GaAs, Ga(AsP)/GaP, and Ga(AsP)/GaAs strained layer superlattices (SLSs), grown either by molecular-beam epitaxy (MBE) or metalorganic chemical vapor deposition (MOCVD), have shown that a mechanism for precipitous stress-relief can be operative, f or room-temperature damage -energy deposition values above - 2 × 10 keV/cm. This phenomenon is correlated with the initial residual compressive stress on the composite structure and is determined by the differences in lattice parameter between the substrate and the buffer alloy-layer.
Ion Implantation Disorder in Strained-Layer Superlattices
- G. W. Arnold, S. T. Picraux, P. S. Peercy, D. R. Myers, R. M. Biefeld, L. R. Dawson
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- Journal:
- MRS Online Proceedings Library Archive / Volume 37 / 1984
- Published online by Cambridge University Press:
- 26 February 2011, 307
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- 1984
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Cantilever-beam bending and RBS channeling measurements have been used to examine implantation-induced disorder and stress buildup in In0.2Ga0.8As/GaAs SLS structures. Implantation fluences from 1011 to 1015/cm2 were used for 150 keV Si, 320 keV Kr, and 250 keV Zn in SLS and GaAs bulk materials. The critical fluence for saturation of compressive stress occurs prior to amorphous layer formation and is followed by stress relief. For all the ions the maximum ion induced stress scales with energy density into atomic processes and stress relief occurs above ∼1 × 1020: keV/cm3. Stress relief is more pronounced for the SLSs than for bulk GaAs. We suggest that stress-relief may lead to slip or other forms of inelastic material flow in SLSs, which would be undesirable for active regions in device applications. Such material flow may be avoided by limiting maximum fluences or by multiplestep implantation and annealing cycles (or hot implants) at high fluences.