19 results
The First Large Absorption Survey in H i (FLASH): I. Science goals and survey design
- James R. Allison, E. M. Sadler, A. D. Amaral, T. An, S. J. Curran, J. Darling, A. C. Edge, S. L. Ellison, K. L. Emig, B. M. Gaensler, L. Garratt-Smithson, M. Glowacki, K. Grasha, B. S. Koribalski, C. del P. Lagos, P. Lah, E. K. Mahony, S. A. Mao, R. Morganti, V. A. Moss, M. Pettini, K. A. Pimbblet, C. Power, P. Salas, L. Staveley-Smith, M. T. Whiting, O. I. Wong, H. Yoon, Z. Zheng, M. A. Zwaan
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- Journal:
- Publications of the Astronomical Society of Australia / Volume 39 / 2022
- Published online by Cambridge University Press:
- 21 March 2022, e010
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We describe the scientific goals and survey design of the First Large Absorption Survey in H i (FLASH), a wide field survey for 21-cm line absorption in neutral atomic hydrogen (H i) at intermediate cosmological redshifts. FLASH will be carried out with the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope and is planned to cover the sky south of $\delta \approx +40\,\deg$ at frequencies between 711.5 and 999.5 MHz. At redshifts between $z = 0.4$ and $1.0$ (look-back times of 4 – 8 Gyr), the H i content of the Universe has been poorly explored due to the difficulty of carrying out radio surveys for faint 21-cm line emission and, at ultra-violet wavelengths, space-borne searches for Damped Lyman- $\alpha$ absorption in quasar spectra. The ASKAP wide field of view and large spectral bandwidth, in combination with a radio-quiet site, will enable a search for absorption lines in the radio spectra of bright continuum sources over 80% of the sky. This survey is expected to detect at least several hundred intervening 21-cm absorbers and will produce an H i-absorption-selected catalogue of galaxies rich in cool, star-forming gas, some of which may be concealed from optical surveys. Likewise, at least several hundred associated 21-cm absorbers are expected to be detected within the host galaxies of radio sources at $0.4 < z < 1.0$ , providing valuable kinematical information for models of gas accretion and jet-driven feedback in radio-loud active galactic nuclei. FLASH will also detect OH 18-cm absorbers in diffuse molecular gas, megamaser OH emission, radio recombination lines, and stacked H i emission.
3.5 THz quantum-cascade laser emission from dual diagonal feedhorns
- B. N. Ellison, A. Valavanis, O. Auriacombe, D. Gerber, T. Rawlings, N. Brewster, M. L. Oldfield, Y. Han, L. H. Li, E. Zafar, E. H. Linfield, A. G. Davies, G. Savini, M. Emes, B. Winter, D. Walker, E. Saenz
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- Journal:
- International Journal of Microwave and Wireless Technologies / Volume 11 / Issue 9 / November 2019
- Published online by Cambridge University Press:
- 08 May 2019, pp. 909-917
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Antenna-pattern measurements obtained from a double-metal supra-terahertz-frequency (supra-THz) quantum cascade laser (QCL) are presented. The QCL is mounted within a mechanically micro-machined waveguide cavity containing dual diagonal feedhorns. Operating in continuous-wave mode at 3.5 THz, and at an ambient temperature of ~60 K, QCL emission has been directed via the feedhorns to a supra-THz detector mounted on a multi-axis linear scanner. Comparison of simulated and measured far-field antenna patterns shows an excellent degree of correlation between beamwidth (full-width-half-maximum) and sidelobe content and a very substantial improvement when compared with unmounted devices. Additionally, a single output has been used to successfully illuminate and demonstrate an optical breadboard arrangement associated with a future supra-THz Earth observation space-borne payload. Our novel device has therefore provided a valuable demonstration of the effectiveness of supra-THz diagonal feedhorns and QCL devices for future space-borne ultra-high-frequency Earth-observing heterodyne radiometers.
M. J. Rubin ed. Studies in Antarctic meteorology. Washington, D.C., American Geophysical Union, 1966. vii, 231 p. (Antarctic Research Series, Vol. 9.) $14.
- T. H. Ellison
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- Journal:
- Journal of Glaciology / Volume 7 / Issue 50 / 1968
- Published online by Cambridge University Press:
- 30 January 2017, pp. 339-340
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The Neutral Hydrogen Cosmological Mass Density at z = 5
- Neil H. M. Crighton, Michael T. Murphy, J. Xavier Prochaska, Gábor Worseck, Marc Rafelski, George D. Becker, Sara L. Ellison, Michele Fumagalli, Sebastian Lopez, Avery Meiksin, John M. O’Meara
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- Journal:
- Proceedings of the International Astronomical Union / Volume 11 / Issue S321 / March 2016
- Published online by Cambridge University Press:
- 21 March 2017, pp. 309-314
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- March 2016
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We present the largest homogeneous survey of redshift > 4.4 damped Lyα systems (DLAs) using the spectra of 163 quasars that comprise the Giant Gemini GMOS (GGG) survey. With this survey we make the most precise high-redshift measurement of the cosmological mass density of neutral hydrogen, ΩHI. After correcting for systematic effects using a combination of mock and higher-resolution spectra, we find ΩHI= 0.98+0.20-0.18 × 10−3 at 〈z〉 = 4.9, assuming a 20% contribution from lower column density systems below the DLA threshold. By comparing to literature measurements at lower redshifts, we show that ΩHI can be described by the functional form ΩHI(z) ∝ (1 + z)0.4. This gradual decrease from z = 5 to 0 suggests that in the galaxies which dominate the cosmic star formation rate, Hi is a transitory gas phase fuelling star formation which must be continually replenished by more highly-ionized gas from the intergalactic medium, and from recycled galactic winds.
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. 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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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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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Genotyping the Future: Scientists' Expectations about Race/Ethnicity after BiDil
- Richard Tutton, Andrew Smart, Paul A. Martin, Richard Ashcroft, George T. H. Ellison
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- Journal of Law, Medicine & Ethics / Volume 36 / Issue 3 / Fall 2008
- Published online by Cambridge University Press:
- 01 January 2021, pp. 464-470
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- Fall 2008
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In a recent discussion about how scientific knowledge might potentially change our understanding of the nature and extent of human genetic, cultural, or biological variation, the sociologist David Skinner identified two competing visions of the future: one that was decidedly dystopian, which conjured up a “re-racialized” future, and an opposing utopian future in which the potential for racialized thinking might be finally overcome. We can situate the ongoing debates about the congestive heart failure drug BiDil, approved by the Food and Drug Administration (FDA) for use only by African Americans, in relation to these differing future prospects.
When the FDA announced its approval of BiDil in June 2005, it located the drug, and perhaps the future of pharmaceutical development, within a particular vision of the future, heralding BiDil as “representing a step toward the promise of personalized medicine.” The discourse of “personalized medicine” can be characterized as part of a utopian future, one in which clinicians will be able to make increasingly individualized decisions based on each patient’s genetic makeup so that the drugs they take will be those that work best for them.
Flaws in the U.S. Food and Drug Administration's Rationale for Supporting the Development and Approval of BiDil as a Treatment for Heart Failure Only in Black Patients
- George T. H. Ellison, Jay S. Kaufman, Rosemary F. Head, Paul A. Martin, Jonathan D. Kahn
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- Journal of Law, Medicine & Ethics / Volume 36 / Issue 3 / Fall 2008
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- 01 January 2021, pp. 449-457
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- Fall 2008
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There is likely to be widespread agreement with much of the FDA’s rationale for approving BiDil (a combination of hydralazine hydrochloride and isosorbide dinitrate; H-I) as a treatment for heart failure. In particular, most would agree that the evidence of effectiveness provided by the African American Heart Failure Trial (A-HeFT) is compelling. Likewise, few health scientists would believe that it is either necessary or responsible to withhold therapies such as BiDil from those who might benefit until there is a full understanding of how they work. And although there is substantial concern that biomedical differences between racial groups are routinely misinterpreted as evidence of innate genetic differences (hence Jonathan Kahn’s call for all such claims to be supported by genetic evidence), most would concede that using race as a “descriptive” variable can help identify differences in health and access/response to treatment that might warrant further investigation or intervention.
Do the changes in energy balance that occur during pregnancy predispose parous women to obesity?
- H. E. Harris, G. T. H. Ellison
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- Nutrition Research Reviews / Volume 10 / Issue 1 / January 1997
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- 14 December 2007, pp. 57-81
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The aim of this review was to re-assess whether the changes in energy balance that accompany pregnancy predispose parous women to obesity. A number of cross-sectional studies have sought to answer this question by examining the relationship between parity and maternal body weight. However, these studies were unable to control for the large number of sociobehavioural confounders that might be responsible for the apparent effect of parity on body weight. Longitudinal studies that examine changes in maternal body weight before and after regnancy avoid these problems by using each mother as her own control. Nevertheless, these studies have to overcome three methodological constraints: They must obtain an accurate measure of prepregnant body weight, they must give each mother sufficient time to lose any weight retained following delivery, and they must take into account the effect of ageing on maternal weight gain during pregnancy and the follow-up period. More than 90% of the studies reviewed found body weight to be greater after pregnancy than it was before (by 0.2–10.6kg). and previous researchers who have examined the evidence for pregnancy-related weight gains suggest that body weight increases by an average of 04–4.8kg following pregnancy. However, only three of the 71 longitudinal studies examined in the present review complied with the three methodological criteria. These studies concluded that mothers gain, on average, 0.9–3.3kg more weight following pregnancy than nonpregnant controls, and that mean body weight remained 0.4–3.0kg higher, even after controlling for a number of sociobehavioural confounders. This apparently modest increase in mean maternal body weight for women having one or two children conceals the fact that some mothers experience a substantial increase in body weight and become obese following pregnancy. It remains unclear whether these increases are simply the result of changes in energy metabolism during pregnancy and lactation, or whether they are influenced by inherent changes in lifestyle that accompany pregnancy and motherhood. Understanding the relative importance of these alternatives might help to explain the aetiology of maternal obesity.
“Clover was a stout motherly mare approaching middle life, who had never quite got her figure back after her fourth foal”
George Well (1945) Animal Farm. London: Secker and Warburg.
Advances in Geophysics. Vol. 6: Atmospheric Diffusion and Air Pollution. Edited by F. N. FRENKIEL and P. A. SHEPPARD. New York: Academic Press, 1959. 471 pp. $12.00.
- T. H. Ellison
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- Journal of Fluid Mechanics / Volume 9 / Issue 1 / September 1960
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- 28 March 2006, pp. 156-158
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Mixing of dense fluid in a turbulent pipe flow Part 2. Dependence of transfer coefficients on local stability
- T. H. Ellison, J. S. Turner
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- Journal of Fluid Mechanics / Volume 8 / Issue 4 / August 1960
- Published online by Cambridge University Press:
- 28 March 2006, pp. 529-544
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This paper continues an investigation into the mixing of a dense layer of salt solution in a turbulent pipe flow in order to obtain a more detailed understanding of the underlying physical processes. The effect of the density difference on the velocity profile in a sloping pipe is calculated using a simplified model, and the results compared with direct measurements obtained by timing streaks of dye at various levels in the pipe. These velocity profiles are also used in conjunction with density profiles to estimate the dependence of the transfer coefficients for salt and momentum KS and KM, on stability.
It is found that KS is much more greatly affected by the density gradient than KM, and that the ratio KS/KM may be represented, to the accuracy of the experiments, as a function of the local Richardson Number Ri. The results agree with what is known of KS/KM in neutral and very stable conditions, and they confirm an earlier prediction by Ellison that the critical flux Richardson number, at which KS becomes zero, is much less than unity.
Finally, a crude semi-empirical method is outlined which indicates how the new measurements of the transfer coefficients may be related to the overall properties of the flow discussed in the first part of the paper.
Turbulent entrainment in stratified flows
- T. H. Ellison, J. S. Turner
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- Journal:
- Journal of Fluid Mechanics / Volume 6 / Issue 3 / October 1959
- Published online by Cambridge University Press:
- 28 March 2006, pp. 423-448
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When a fluid which is lighter than its surroundings is emitted by a source under a sloping roof (or a heavier fluid from a source on a sloping floor), it may flow as a relatively thin turbulent layer. The motion of this layer is governed by the rate at which it entrains the ambient fluid. A theory is presented in which it is assumed that the entrainment is proportional to the velocity of the layer multiplied by an empirical function, E(Ri), of the overall Richardson number for the layer defined by Ri = g(ρa - ρ) h/ρaV2. This theory predicts that in most practical cases the layer will rapidly attain an equilibrium state in which Ri does not vary with distance downstream, and the gravitational force on the layer is just balanced by the drag due to entrainment together with friction on the floor or roof.
Two series of laboratory experiments are described from which E(Ri) can be determined. In the first, the spread of a surface jet of fluid lighter than that over which it is flowing is measured; in the second, a study is made of the flow of a heavy liquid down the sloping floor of a channel. These experiments show that E falls off rapidly as Ri increases and is probably negligible when Ri is more than about 0·8.
The theoretical and experimental results allow predictions to be made of flow velocities once the rate of supply of density difference is known. An estimate is also given of the uniform velocity which the ambient fluid must possess in order to cause the motion of the layer to be reversed.
Turbulent transport of heat and momentum from an infinite rough plane
- T. H. Ellison
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- Journal:
- Journal of Fluid Mechanics / Volume 2 / Issue 5 / July 1957
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- 28 March 2006, pp. 456-466
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In the first part of the paper the dimensional laws governing the processes of heat and momentum transport from an infinite rough plane are assembled and their consequences set out. In the second part, the detailed equations for the turbulent energy, the mean square temperature fluctuation and the covariance of temperature and vertical velocity are used, together with some speculative assumptions concerning the dissipative action of the turbulence, to derive a series of relations between the turbulent intensities and the Austausch coefficients. One of these relations indicates that the flux form of the Richardson number cannot exceed a critical value which is about 0·15. It follows that in highly stable conditions the buoyancy forces have little direct effect on the turbulent energy balance, their action being primarily to cause a reduction in the scale of the motion and some change in its structure.
Mixing of dense fluid in a turbulent pipe flow Part 1. Overall description of the flow
- T. H. Ellison, J. S. Turner
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- Journal:
- Journal of Fluid Mechanics / Volume 8 / Issue 4 / August 1960
- Published online by Cambridge University Press:
- 28 March 2006, pp. 514-528
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This paper concerns an investigation into the behaviour of a layer of dense salt solution on the floor of a sloping rectangular pipe in which there is a turbulent flow. The various phenomena which are observed are described qualitatively and by the presentation of typical concentration profiles.
Numerical values are obtained experimentally for the rates of spread of the edge of the layer in the case where the salt is moving entirely in the direction of the main stream. The rate of spread is found to depend mainly on the slope α and on the pipe Richardson number, defined by Rip = DΔd cos α/V2, where D is the depth of the pipe, Δd = g(ρd−ρa)/ρa, ρd is the density of the fully mixed discharge and ρa is the density of the ambient flow. In the range of Riρ from 0 to 0·005 the rate of spread of the layer decreases by a factor of about 3 at small slopes.
Some discussion is given of the factors determining the initial rate of spread just after the layer leaves the slit. Finally, it is shown how the depth measurements can be related to the determination of the concentration at the floor.
A note on the velocity profile and longitudinal mixing in a broad open channel
- T. H. Ellison
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- Journal:
- Journal of Fluid Mechanics / Volume 8 / Issue 1 / May 1960
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- 28 March 2006, pp. 33-40
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The mean velocity profile near the surface of turbulent flow in a broad open channel is discussed with dimensional arguments, and a new empirical constant m is introduced which is analogous to von Kármán's constant for flow near a rigid boundary. It is shown that, while the velocity profile depends only rather weakly on m, the dependence of the coefficient of apparent longitudinal diffusion is stronger, and measurements of diffusion could, in principle, provide an accurate determination of its value. The new profiles for various values of m are compared with those in current use, and finally the correction for finite Reynolds number is discussed.
ANTHROPOLOGICAL INSIGHTS INTO THE USE OF RACE/ETHNICITY TO EXPLORE GENETIC CONTRIBUTIONS TO DISPARITIES IN HEALTH
- SIMON M. OUTRAM, GEORGE T. H. ELLISON
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- Journal of Biosocial Science / Volume 38 / Issue 1 / January 2006
- Published online by Cambridge University Press:
- 03 November 2005, pp. 83-102
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Anthropological insights into the use of race/ethnicity to explore genetic contributions to disparities in health were developed using in-depth qualitative interviews with editorial staff from nineteen genetics journals, focusing on the methodological and conceptual mechanisms required to make race/ethnicity a genetic variable. As such, these analyses explore how and why race/ethnicity comes to be used in the context of genetic research, set against the background of continuing critiques from anthropology and related human sciences that focus on the social construction, structural correlates and limited genetic validity of racial/ethnic categories. The analyses demonstrate how these critiques have failed to engage geneticists, and how geneticists use a range of essentially cultural devices to protect and separate their use of race/ethnicity as a genetic construct from its use as a societal and social science resource. Given its multidisciplinary, biosocial nature and the cultural gaze of its ethnographic methodologies, anthropology is well placed to explore the cultural separation of science and society, and of natural and social science disciplines. Anthropological insights into the use of race/ethnicity to explore disparities in health suggest that moving beyond genetic explanations of innate difference might benefit from a more even-handed critique of how both the natural and social sciences tend to essentialize selective elements of race/ethnicity. Drawing on the example of HIV/AIDS, this paper demonstrates how public health has been undermined by the use of race/ethnicity as an analytical variable, both as a cipher for innate genetic differences in susceptibility and response to treatment, and in its use to identify ‘core groups’ at greater risk of becoming infected and infecting others. Clearly, a tendency for biological reductionism can place many biomedical issues beyond the scope of public health interventions, while socio-cultural essentialization has tended to stigmatize ‘unhealthy behaviours’ and the communities where these are more prevalent.
10 - Postscript: reflections on HIV/AIDS and history
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- By Shula Marks, Professor, School of Oriental and African Studies, University of London, London, WC1H 0XG, George T. H. Ellison, Professor of Public Health and Director of the Institute of Primary Care and Public Health, South Bank University, London
- Edited by George Ellison, South Bank University, London, Melissa Parker, Brunel University, Catherine Campbell, London School of Economics and Political Science
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- Book:
- Learning from HIV and AIDS
- Published online:
- 14 January 2010
- Print publication:
- 30 October 2003, pp 268-292
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Summary
Some 10 years ago, the British medical historian Virginia Berridge (1992a: 326), strikingly declared: ‘History and historians have had a significant role in interpreting the AIDS epidemic … History, in some national responses to AIDS, became a direct policy-relevant science.’ At the outset, she argued, history was used in two ways: as a form of background knowledge; and as ‘“historical partisanship”, the use of historical example to advance particular policy positions’ (Berridge, 1992a: 326). It entered the policy debate directly and, at least in the UK, ensured a liberal non-punitive approach to people with HIV/AIDS. Analysing the chapters in the pioneering volume edited by Elizabeth Fee and Daniel Fox (1989) she showed how, in the early days of the disease, the presence of historians at international conferences was assiduously courted in the United States and the UK. They were called on to deal with earlier public health and popular responses to the spread of infectious (especially sexually transmitted) disease – quarantine and compulsory vaccination – all of which had relevance to the contemporary debate. Even more surprisingly, she maintained, leading medical authorities (notably Sir Donald Acheson, Chief Medical Officer at the Department of Health, and Michael Adler at the Middlesex Hospital) had themselves drawn direct analogies with the past and addressed historical precedents in their advocacy of a liberal public health policy (Berridge, 1992b; see also: Berridge, 1992a; Berridge and Strong, 1993; Berridge, 1996).
1 - Introduction. Learning from HIV and AIDS: from multidisciplinary to interdisciplinarity
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- By George T. H. Ellison, Professor of Public Health and Director of the Institute of Primary Care and Public Health, South Bank University, London, Melissa Parker, Director of the International Medical Anthropology Programme, Brunel University in London, Catherine Campbell, Reader in Social Psychology, London School of Economics and Political Science; Professor, University of Natal, Durban
- Edited by George Ellison, South Bank University, London, Melissa Parker, Brunel University, Catherine Campbell, London School of Economics and Political Science
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- Book:
- Learning from HIV and AIDS
- Published online:
- 14 January 2010
- Print publication:
- 30 October 2003, pp 1-31
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Summary
This disease is not like any other … in the 20 years since the disease was recognised, more than 20 million people have died from it. Another 40 million are infected. New infections are occurring at the rate of 15,000 a day, and the rate is still increasing. Unless there is a significant change for the better almost all these people will die.
The Economist, July 11th 2002[A]t current infection rates, AIDS, the deadliest epidemic in human history, will kill 68 million people in the 45 most affected countries over the next 20 years …”
Peter Piot, Executive Director of UNAIDS, writing in the New York Times in July 2002‘Learning from HIV and AIDS’ – a multidisciplinary symposium of the UK BioSocial Society
Mindful of the extraordinary contribution made by health professionals, academics, policy makers and the communities worst affected to understand and respond to HIV/AIDS, the UK BioSocial Society invited representatives from these groups to a multidisciplinary symposium held at the Institute of Education in May 2001. The sheer scale of the HIV/AIDS pandemic has resulted in unprecedented research activity, both theoretical and applied, and has led to a huge array of formal and informal publications (ranging from dedicated academic journals and professional texts, to local newsletters and global websites). For the most part, however, these cover responses to HIV/AIDS – at the individual-, familial-, communal-, institutional-, national-, regional- and global-level.
5 - What have clinicians learnt from working with HIV/AIDS? A medical perspective from London
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- By Chris G. A. Wood, HIV Unit, North Middlesex University Hospital, London N18 1QX, UK, George T. H. Ellison, Professor of Public Health and Director of the Institute of Primary Care and Public Health, South Bank University, London
- Edited by George Ellison, South Bank University, London, Melissa Parker, Brunel University, Catherine Campbell, London School of Economics and Political Science
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- Book:
- Learning from HIV and AIDS
- Published online:
- 14 January 2010
- Print publication:
- 30 October 2003, pp 111-147
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Summary
Introduction
This chapter sets out to provide a narrative account of learning from HIV and AIDS drawn from the perspective of a clinician (CW) who has been working with HIV/AIDS patients in London since 1990. It draws on CW's clinical experience gained during his initial specialist HIV training at the Chelsea and Westminster Hospital in Central London from 1990 to 1993, and on his experiences of working at the HIV Unit at the North Middlesex University Hospital (NMUH), a district general hospital in Edmonton), and in the Sexual Health Centre at St Ann's Hospital in Tottenham, both in North London. The community served by these two hospitals might best be described as ‘inner–outer London’ – a multicultural, multiethnic community with a large and diverse population comprising long-term residents and recent immigrants, including refugees and asylum seekers, living in an area with high levels of social deprivation, unemployment and welfare support. This local community happens to reflect the pattern of HIV infection globally and therefore provides an ideal setting from which to consider the impact of the disease on clinical perspectives and clinical practice, as well as some of the social and cultural dimensions of HIV/AIDS in the UK.
By reflecting on clinical practice this chapter aims to demonstrate how, despite the changing clinical context of HIV/AIDS in London, the barriers to treatment and therapy are common to many of the groups most at risk.
Are overweight women at increased risk of obesity following pregnancy?
- H. E. Harris, G. T. H. Ellison, L. M. Richter, T. De Wet, J. Levin
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- Journal:
- British Journal of Nutrition / Volume 79 / Issue 6 / June 1998
- Published online by Cambridge University Press:
- 09 March 2007, pp. 489-494
- Print publication:
- June 1998
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Longitudinal studies suggest that women who already have a high BMI are at greater risk of maternal obesity than their lighter counterparts. The aim of the present study was to investigate this possibility by examining the relationship between reproductive history and maternal BMI in a community of 627 women from South Africa with a high prevalence of obesity. Standardized questionnaires were used to obtain detailed sociodemographic and behavioural information, while maternal weight and height were both measured at the time of the interview. Analysis of covariance (ANCOVA) showed that maternal age (r2 0·015, P = 0·001), smoking status (r2 0·012, P = 0·036), and social support (r2 0·011, P = 0·006) were all independently associated with maternal BMI. If overweight women were at increased risk of maternal obesity, then the positive relationship between reproductive history and maternal BMI should be enhanced in this relatively obese community, yet the ANCOVA models showed no independent association between gravidity and maternal BMI after controlling for the effects of confounding factors. Although previous longitudinal studies have found a positive association between prepregnant weight and long-term weight gain, this relationship might arise because overweight women gain more weight over a fixed period of time than normal weight women, and therefore they may appear to be at greater risk of pregnancy-related weight gains. Overweight women are at greater risk of weight gain generally, but there is little unequivocal evidence to suggest that they are at any increased risk of maternal obesity, when compared with women of lower BMI.