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Mapping the Distributions of Exoplanet Populations with NICI and GPI
- Eric L. Nielsen, Michael C. Liu, Zahed Wahhaj, Beth A. Biller, Thomas L. Hayward, Laird M. Close, the Gemini NICI Planet-Finding Campaign Team, Bruce Macintosh, Dmitry Savransky, Jason J. Wang, James R. Graham, Robert J. De Rosa, Abhijith Rajan, the GPIES Consortium
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- Journal:
- Proceedings of the International Astronomical Union / Volume 10 / Issue S314 / November 2015
- Published online by Cambridge University Press:
- 27 January 2016, pp. 220-225
- Print publication:
- November 2015
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While more and more long-period giant planets are discovered by direct imaging, the distribution of planets at these separations (≳5 AU) has remained largely uncertain, especially compared to planets in the inner regions of solar systems probed by RV and transit techniques. The low frequency, the detection challenges, and heterogeneous samples make determining the mass and orbit distributions of directly imaged planets at the end of a survey difficult. By utilizing Monte Carlo methods that incorporate the age, distance, and spectral type of each target, we can use all stars in the survey, not just those with detected planets, to learn about the underlying population. We have produced upper limits and direct measurements of the frequency of these planets with the most recent generation of direct imaging surveys. The Gemini NICI Planet-Finding Campaign observed 220 young, nearby stars at a median H-band contrast of 14.5 magnitudes at 1”, representing the largest, deepest search for exoplanets by the completion of the survey. The Gemini Planet Imager Exoplanet Survey is in the process of surveying 600 stars, pushing these contrasts to a few tenths of an arcsecond from the star. With the advent of large surveys (many hundreds of stars) using advanced planet-imagers we gain the ability to move beyond measuring the frequency of wide-separation giant planets and to simultaneously determine the distribution as a function of planet mass, semi-major axis, and stellar mass, and so directly test models of planet formation and evolution.
Suitable habitat for recolonizing large carnivores in the midwestern USA
- Julia B. Smith, Clayton K. Nielsen, Eric C. Hellgren
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Large carnivores are recolonizing parts of North America and Europe as a result of modern management and conservation policy. In the midwestern USA, black bears Ursus americanus, cougars Puma concolor and grey wolves Canis lupus have the potential to recolonize provided there is suitable habitat. Understanding where large carnivores may become re-established will prepare resource professionals for the inevitable ecosystem effects and potential human–carnivore conflicts associated with these species. We developed individual and combined models of suitable habitat for black bears, cougars and wolves in 18 midwestern states, using geospatial data, expert-opinion surveys, and multi-criteria evaluation. Large, contiguous areas of suitable habitat comprised 35, 21 and 13% of the study region for wolves, bears and cougars, respectively. Approximately 12% of the region was considered suitable for all three species. Arkansas, Minnesota, Texas and Wisconsin had the highest proportions (> 40%) of suitable habitat for black bears; Arkansas, Michigan, Missouri, Texas and Wisconsin had the highest proportions (≥ 20%) of suitable habitat for cougars; and only in four states in the study region was < 29% of land suitable wolf habitat. Models performed well when validated by comparing suitability values of independent sets of known carnivore locations to those of random locations. Contiguous areas of suitable habitat typically spanned multiple states, thus coordination across boundaries and among agencies will be vital to successful conservation of these species. Our models highlight differences in habitat requirements and geographical distribution of potential habitat among these carnivores, as well as areas vital to their persistence in the Midwest.
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- By Mitchell Aboulafia, Frederick Adams, Marilyn McCord Adams, Robert M. Adams, Laird Addis, James W. Allard, David Allison, William P. Alston, Karl Ameriks, C. Anthony Anderson, David Leech Anderson, Lanier Anderson, Roger Ariew, David Armstrong, Denis G. Arnold, E. J. Ashworth, Margaret Atherton, Robin Attfield, Bruce Aune, Edward Wilson Averill, Jody Azzouni, Kent Bach, Andrew Bailey, Lynne Rudder Baker, Thomas R. Baldwin, Jon Barwise, George Bealer, William Bechtel, Lawrence C. Becker, Mark A. Bedau, Ernst Behler, José A. Benardete, Ermanno Bencivenga, Jan Berg, Michael Bergmann, Robert L. Bernasconi, Sven Bernecker, Bernard Berofsky, Rod Bertolet, Charles J. Beyer, Christian Beyer, Joseph Bien, Joseph Bien, Peg Birmingham, Ivan Boh, James Bohman, Daniel Bonevac, Laurence BonJour, William J. Bouwsma, Raymond D. Bradley, Myles Brand, Richard B. Brandt, Michael E. Bratman, Stephen E. Braude, Daniel Breazeale, Angela Breitenbach, Jason Bridges, David O. Brink, Gordon G. Brittan, Justin Broackes, Dan W. Brock, Aaron Bronfman, Jeffrey E. Brower, Bartosz Brozek, Anthony Brueckner, Jeffrey Bub, Lara Buchak, Otavio Bueno, Ann E. Bumpus, Robert W. Burch, John Burgess, Arthur W. Burks, Panayot Butchvarov, Robert E. Butts, Marina Bykova, Patrick Byrne, David Carr, Noël Carroll, Edward S. Casey, Victor Caston, Victor Caston, Albert Casullo, Robert L. Causey, Alan K. L. Chan, Ruth Chang, Deen K. Chatterjee, Andrew Chignell, Roderick M. Chisholm, Kelly J. Clark, E. J. Coffman, Robin Collins, Brian P. Copenhaver, John Corcoran, John Cottingham, Roger Crisp, Frederick J. Crosson, Antonio S. Cua, Phillip D. Cummins, Martin Curd, Adam Cureton, Andrew Cutrofello, Stephen Darwall, Paul Sheldon Davies, Wayne A. Davis, Timothy Joseph Day, Claudio de Almeida, Mario De Caro, Mario De Caro, John Deigh, C. F. Delaney, Daniel C. Dennett, Michael R. DePaul, Michael Detlefsen, Daniel Trent Devereux, Philip E. Devine, John M. Dillon, Martin C. Dillon, Robert DiSalle, Mary Domski, Alan Donagan, Paul Draper, Fred Dretske, Mircea Dumitru, Wilhelm Dupré, Gerald Dworkin, John Earman, Ellery Eells, Catherine Z. Elgin, Berent Enç, Ronald P. Endicott, Edward Erwin, John Etchemendy, C. Stephen Evans, Susan L. Feagin, Solomon Feferman, Richard Feldman, Arthur Fine, Maurice A. Finocchiaro, William FitzPatrick, Richard E. Flathman, Gvozden Flego, Richard Foley, Graeme Forbes, Rainer Forst, Malcolm R. Forster, Daniel Fouke, Patrick Francken, Samuel Freeman, Elizabeth Fricker, Miranda Fricker, Michael Friedman, Michael Fuerstein, Richard A. Fumerton, Alan Gabbey, Pieranna Garavaso, Daniel Garber, Jorge L. A. Garcia, Robert K. Garcia, Don Garrett, Philip Gasper, Gerald Gaus, Berys Gaut, Bernard Gert, Roger F. Gibson, Cody Gilmore, Carl Ginet, Alan H. Goldman, Alvin I. Goldman, Alfonso Gömez-Lobo, Lenn E. Goodman, Robert M. Gordon, Stefan Gosepath, Jorge J. E. Gracia, Daniel W. Graham, George A. Graham, Peter J. Graham, Richard E. Grandy, I. Grattan-Guinness, John Greco, Philip T. Grier, Nicholas Griffin, Nicholas Griffin, David A. Griffiths, Paul J. Griffiths, Stephen R. Grimm, Charles L. Griswold, Charles B. Guignon, Pete A. Y. Gunter, Dimitri Gutas, Gary Gutting, Paul Guyer, Kwame Gyekye, Oscar A. Haac, Raul Hakli, Raul Hakli, Michael Hallett, Edward C. Halper, Jean Hampton, R. James Hankinson, K. R. Hanley, Russell Hardin, Robert M. Harnish, William Harper, David Harrah, Kevin Hart, Ali Hasan, William Hasker, John Haugeland, Roger Hausheer, William Heald, Peter Heath, Richard Heck, John F. Heil, Vincent F. Hendricks, Stephen Hetherington, Francis Heylighen, Kathleen Marie Higgins, Risto Hilpinen, Harold T. Hodes, Joshua Hoffman, Alan Holland, Robert L. Holmes, Richard Holton, Brad W. Hooker, Terence E. Horgan, Tamara Horowitz, Paul Horwich, Vittorio Hösle, Paul Hoβfeld, Daniel Howard-Snyder, Frances Howard-Snyder, Anne Hudson, Deal W. Hudson, Carl A. Huffman, David L. Hull, Patricia Huntington, Thomas Hurka, Paul Hurley, Rosalind Hursthouse, Guillermo Hurtado, Ronald E. Hustwit, Sarah Hutton, Jonathan Jenkins Ichikawa, Harry A. Ide, David Ingram, Philip J. Ivanhoe, Alfred L. Ivry, Frank Jackson, Dale Jacquette, Joseph Jedwab, Richard Jeffrey, David Alan Johnson, Edward Johnson, Mark D. Jordan, Richard Joyce, Hwa Yol Jung, Robert Hillary Kane, Tomis Kapitan, Jacquelyn Ann K. Kegley, James A. Keller, Ralph Kennedy, Sergei Khoruzhii, Jaegwon Kim, Yersu Kim, Nathan L. King, Patricia Kitcher, Peter D. Klein, E. D. Klemke, Virginia Klenk, George L. Kline, Christian Klotz, Simo Knuuttila, Joseph J. Kockelmans, Konstantin Kolenda, Sebastian Tomasz Kołodziejczyk, Isaac Kramnick, Richard Kraut, Fred Kroon, Manfred Kuehn, Steven T. Kuhn, Henry E. Kyburg, John Lachs, Jennifer Lackey, Stephen E. Lahey, Andrea Lavazza, Thomas H. Leahey, Joo Heung Lee, Keith Lehrer, Dorothy Leland, Noah M. Lemos, Ernest LePore, Sarah-Jane Leslie, Isaac Levi, Andrew Levine, Alan E. Lewis, Daniel E. Little, Shu-hsien Liu, Shu-hsien Liu, Alan K. L. Chan, Brian Loar, Lawrence B. Lombard, John Longeway, Dominic McIver Lopes, Michael J. Loux, E. J. Lowe, Steven Luper, Eugene C. Luschei, William G. Lycan, David Lyons, David Macarthur, Danielle Macbeth, Scott MacDonald, Jacob L. Mackey, Louis H. Mackey, Penelope Mackie, Edward H. Madden, Penelope Maddy, G. B. Madison, Bernd Magnus, Pekka Mäkelä, Rudolf A. Makkreel, David Manley, William E. Mann (W.E.M.), Vladimir Marchenkov, Peter Markie, Jean-Pierre Marquis, Ausonio Marras, Mike W. Martin, A. P. Martinich, William L. McBride, David McCabe, Storrs McCall, Hugh J. McCann, Robert N. McCauley, John J. McDermott, Sarah McGrath, Ralph McInerny, Daniel J. McKaughan, Thomas McKay, Michael McKinsey, Brian P. McLaughlin, Ernan McMullin, Anthonie Meijers, Jack W. Meiland, William Jason Melanson, Alfred R. Mele, Joseph R. Mendola, Christopher Menzel, Michael J. Meyer, Christian B. Miller, David W. Miller, Peter Millican, Robert N. Minor, Phillip Mitsis, James A. Montmarquet, Michael S. Moore, Tim Moore, Benjamin Morison, Donald R. Morrison, Stephen J. Morse, Paul K. Moser, Alexander P. D. Mourelatos, Ian Mueller, James Bernard Murphy, Mark C. Murphy, Steven Nadler, Jan Narveson, Alan Nelson, Jerome Neu, Samuel Newlands, Kai Nielsen, Ilkka Niiniluoto, Carlos G. Noreña, Calvin G. Normore, David Fate Norton, Nikolaj Nottelmann, Donald Nute, David S. Oderberg, Steve Odin, Michael O’Rourke, Willard G. Oxtoby, Heinz Paetzold, George S. Pappas, Anthony J. Parel, Lydia Patton, R. P. Peerenboom, Francis Jeffry Pelletier, Adriaan T. Peperzak, Derk Pereboom, Jaroslav Peregrin, Glen Pettigrove, Philip Pettit, Edmund L. Pincoffs, Andrew Pinsent, Robert B. Pippin, Alvin Plantinga, Louis P. Pojman, Richard H. Popkin, John F. Post, Carl J. Posy, William J. Prior, Richard Purtill, Michael Quante, Philip L. Quinn, Philip L. Quinn, Elizabeth S. Radcliffe, Diana Raffman, Gerard Raulet, Stephen L. Read, Andrews Reath, Andrew Reisner, Nicholas Rescher, Henry S. Richardson, Robert C. Richardson, Thomas Ricketts, Wayne D. Riggs, Mark Roberts, Robert C. Roberts, Luke Robinson, Alexander Rosenberg, Gary Rosenkranz, Bernice Glatzer Rosenthal, Adina L. Roskies, William L. Rowe, T. M. Rudavsky, Michael Ruse, Bruce Russell, Lilly-Marlene Russow, Dan Ryder, R. M. Sainsbury, Joseph Salerno, Nathan Salmon, Wesley C. Salmon, Constantine Sandis, David H. Sanford, Marco Santambrogio, David Sapire, Ruth A. Saunders, Geoffrey Sayre-McCord, Charles Sayward, James P. Scanlan, Richard Schacht, Tamar Schapiro, Frederick F. Schmitt, Jerome B. Schneewind, Calvin O. Schrag, Alan D. Schrift, George F. Schumm, Jean-Loup Seban, David N. Sedley, Kenneth Seeskin, Krister Segerberg, Charlene Haddock Seigfried, Dennis M. Senchuk, James F. Sennett, William Lad Sessions, Stewart Shapiro, Tommie Shelby, Donald W. Sherburne, Christopher Shields, Roger A. Shiner, Sydney Shoemaker, Robert K. Shope, Kwong-loi Shun, Wilfried Sieg, A. John Simmons, Robert L. Simon, Marcus G. Singer, Georgette Sinkler, Walter Sinnott-Armstrong, Matti T. Sintonen, Lawrence Sklar, Brian Skyrms, Robert C. Sleigh, Michael Anthony Slote, Hans Sluga, Barry Smith, Michael Smith, Robin Smith, Robert Sokolowski, Robert C. Solomon, Marta Soniewicka, Philip Soper, Ernest Sosa, Nicholas Southwood, Paul Vincent Spade, T. L. S. Sprigge, Eric O. Springsted, George J. Stack, Rebecca Stangl, Jason Stanley, Florian Steinberger, Sören Stenlund, Christopher Stephens, James P. Sterba, Josef Stern, Matthias Steup, M. A. Stewart, Leopold Stubenberg, Edith Dudley Sulla, Frederick Suppe, Jere Paul Surber, David George Sussman, Sigrún Svavarsdóttir, Zeno G. Swijtink, Richard Swinburne, Charles C. Taliaferro, Robert B. Talisse, John Tasioulas, Paul Teller, Larry S. Temkin, Mark Textor, H. S. Thayer, Peter Thielke, Alan Thomas, Amie L. Thomasson, Katherine Thomson-Jones, Joshua C. Thurow, Vzalerie Tiberius, Terrence N. Tice, Paul Tidman, Mark C. Timmons, William Tolhurst, James E. Tomberlin, Rosemarie Tong, Lawrence Torcello, Kelly Trogdon, J. D. Trout, Robert E. Tully, Raimo Tuomela, John Turri, Martin M. Tweedale, Thomas Uebel, Jennifer Uleman, James Van Cleve, Harry van der Linden, Peter van Inwagen, Bryan W. Van Norden, René van Woudenberg, Donald Phillip Verene, Samantha Vice, Thomas Vinci, Donald Wayne Viney, Barbara Von Eckardt, Peter B. M. Vranas, Steven J. Wagner, William J. Wainwright, Paul E. Walker, Robert E. Wall, Craig Walton, Douglas Walton, Eric Watkins, Richard A. Watson, Michael V. Wedin, Rudolph H. Weingartner, Paul Weirich, Paul J. Weithman, Carl Wellman, Howard Wettstein, Samuel C. Wheeler, Stephen A. White, Jennifer Whiting, Edward R. Wierenga, Michael Williams, Fred Wilson, W. Kent Wilson, Kenneth P. Winkler, John F. Wippel, Jan Woleński, Allan B. Wolter, Nicholas P. Wolterstorff, Rega Wood, W. Jay Wood, Paul Woodruff, Alison Wylie, Gideon Yaffe, Takashi Yagisawa, Yutaka Yamamoto, Keith E. Yandell, Xiaomei Yang, Dean Zimmerman, Günter Zoller, Catherine Zuckert, Michael Zuckert, Jack A. Zupko (J.A.Z.)
- Edited by Robert Audi, University of Notre Dame, Indiana
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- Book:
- The Cambridge Dictionary of Philosophy
- Published online:
- 05 August 2015
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- 27 April 2015, pp ix-xxx
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- By Agoston T. Agoston, Syed Z. Ali, Mahul B. Amin, Daniel A. Arber, Pedram Argani, Sylvia L. Asa, Rebecca N. Baergen, Zubair W. Baloch, Andrew M. Bellizzi, Kurt Benirschke, Allen Burke, Kenneth B. Calder, Karen L. Chang, Rebecca D. Chernock, Wang Cheung, Thomas V. Colby, Byron P. Croker, Ronald A. DeLellis, Edward F. DiCarlo, Ralph C. Eagle, Hormoz Ehya, Brett M. Elicker, Tarik M. Elsheikh, Robert E. Fechner, Linda D. Ferrell, Melina B. Flanagan, Douglas B. Flieder, Christopher S. Foster, Lillian Gaber, Karuna Garg, Kim R. Geisinger, Ryan M. Gill, Eric F. Glassy, David J. Glembocki, Zachary D. Goodman, Robert O. Greer, David J. Grignon, Gerardo E. Guiter, Kymberly A. Gyure, Ian S. Hagemann, Michael R. Henry, Jason L. Hornick, Ralph H. Hruban, Phyllis C. Huettner, Peter A. Humphrey, Olga B. Ioffe, Edward C. Klatt, Michael J. Klein, Ernest E. Lack, James N. Lampros, Lester J. Layfield, Robin D. LeGallo, Kevin O. Leslie, James S. Lewis, Virginia A. LiVolsi, Alberto M. Marchevsky, Anne Marie McNicol, Mitra Mehrad, Elizabeth Montgomery, Cesar A. Moran, Christopher A. Moskaluk, George J. Netto, G. Petur Nielsen, Robert D. Odze, Arthur S. Patchefsky, James W. Patterson, Elizabeth N. Pavlisko, John D. Pfeifer, Celeste N. Powers, Richard A. Prayson, Anja C. Roden, Victor L. Roggli, Andrew E. Rosenberg, Sherif Said, Margie A. Scott, Raja R. Seethala, Carlie S. Sigel, Jan F. Silverman, Bruce R. Smoller, Edward B. Stelow, Nora C. J. Sun, Mark W. Teague, Satish K. Tickoo, Thomas M. Ulbright, Paul E. Wakely, Jun Wang, Lawrence M. Weiss, Mark R. Wick, Howard H. Wu, Rhonda K. Yantiss, Charles Zaloudek, Yaxia Zhang, Xiaohui Sheila Zhao
- Edited by Mark R. Wick, University of Virginia, Virginia A. LiVolsi, University of Pennsylvania School of Medicine, John D. Pfeifer, Washington University School of Medicine, St Louis, Edward B. Stelow, University of Virginia, Paul E. Wakely, Jr
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- Silverberg's Principles and Practice of Surgical Pathology and Cytopathology
- Published online:
- 13 March 2015
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- 26 March 2015, pp vii-x
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The implications of bent jets in galaxy groups
- Danielle M. Nielsen, Eric M. Wilcots
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- Proceedings of the International Astronomical Union / Volume 10 / Issue S313 / September 2014
- Published online by Cambridge University Press:
- 24 March 2015, pp. 303-304
- Print publication:
- September 2014
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Bent-double sources, sometimes referred to as wide- or narrow-angle tails, are most likely the result of ram pressure from either the motion of the source through a dense medium or the "cluster weather." These unusual sources have long been associated with high density, high velocity dispersion, and turbulent environments of massive clusters, however a surprising number have been found in lower mass systems. We focus our attention on a sample of such sources in galaxy groups where the velocity dispersion is significantly lower. We have acquired multi-frequency radio continuum observations using the GMRT of our bent-double sample and new optical spectroscopy to measure the velocity dispersion of groups hosting these bent-double sources. Our goal is to derive an estimate of the density of the intergalactic medium in these groups. Here, we present GMRT data for one source in our sample.
The Gemini NICI Planet-Finding Campaign: The Frequency of Giant Planets around Young B and A Stars
- Eric L. Nielsen, Michael C. Liu, Zahed Wahhaj, Beth A. Biller, Thomas L. Hayward, The Gemini NICI Planet-Finding Campaign Team
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- Journal:
- Proceedings of the International Astronomical Union / Volume 8 / Issue S299 / June 2013
- Published online by Cambridge University Press:
- 06 January 2014, pp. 60-61
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- June 2013
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We have carried out high contrast imaging of 70 young, nearby B and A stars to search for brown dwarf and planetary companions as part of the Gemini NICI Planet-Finding Campaign. Our survey represents the largest, deepest survey for planets around high-mass stars (≈1.5–2.5 M⊙) conducted to date and includes the planet hosts β Pic and Fomalhaut. Despite detecting two new brown dwarfs, our observations did not detect new planets around our target stars, and we present upper limits on the fraction of high-mass stars that can host giant planets that are consistent with our null result.
Contributors
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- By Maricela Alarcón, Laura A. Baker, Trygve Bakken, Serena Bezdjian, Andrew W. Bergen, Laura J. Bierut, Andrew C. Chen, C. Robert Cloninger, David W. Craig, Anibal Cravchik, Raymond R. Crowe, Carlos Cruchaga, Joseph F. Cubells, Marcella Devoto, Stephen H. Dinwiddie, Howard J. Edenberg, Josephine Elia, Craig A. Erickson, Thomas V. Fernandez, Xiaowu Gai, Elliot Gershon, Daniel H. Geschwind, Alison M. Goate, Hugh M. D. Gurling, Hakon Hakonarson, Sarah M. Hartz, Akiko Hayashi-Takagi, Jinger Hoop, Hanna Jaaro-Peled, Atsushi Kamiya, John S. K. Kauwe, Walter H. Kaye, John R. Kelsoe, Karestan C. Koenen, Mary Jeanne Kreek, Francesca Lantieri, James F. Leckman, Ondrej Libiger, Falk W. Lohoff, Michael J. Lyons, Christopher J. McDougle, Andrew McQuillin, Kathleen Ries Merikangas, Maria G. Motlagh, Pablo R. Moya, Dennis L. Murphy, Eric J. Nestler, Alexander B. Niculescu, David A. Nielsen, Khendra I. Peay, Bernice Porjesz, James B. Potash, R. Arlen Price, Dmitri Proudnikov, Adrian Raine, Madhavi Rangaswamy, William Renthal, Akira Sawa, Nicholas J. Schork, Saurav Seshadri, Shelley D. Smith, Wanli W. Smith, Toshinobu Takeda, Ardesheer Talati, Yi-Lang Tang, Kiara Timpano, Ali Torkamani, Catherine Tuvblad, Myrna M. Weissman, Jens R. Wendland, Jennifer Wessel, Peter S. White, Vadim Yuferov, Tyler Zink
- Edited by John I. Nurnberger, Jr, Wade Berrettini, University of Pennsylvania School of Medicine
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- Book:
- Principles of Psychiatric Genetics
- Published online:
- 05 October 2012
- Print publication:
- 13 September 2012, pp vii-x
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- By Dag Aarsland, Adrià Arboix, Carlos Bazán, James T. Becker, Sylvie Belleville, Kevin M. Biglan, Sandra E. Black, Mariana Blanco, Rémi W. Bouchard, Bruce J. Brew, David J. Burn, Leonardo Caixeta, Richard Camicioli, Paulo Caramelli, Neil Cashman, Nicholas W. S. Davies, Yan Deschaintre, Rachel S. Doody, Bruno Dubois, Uwe Ehrt, Stephane Epelbaum, Ryan V. V. Evans, Joseph M. Ferrara, Bruno Franchi, Morris Freedman, Anders Gade, Serge Gauthier, Marta Grau-Olivares, Matthew E. Growdon, Will Guest, Marie Christie Guiot, Shahul Hameed, Mirna Lie Hosogi-Senaha, Ging-Yuek Robin Hsiung, Masamichi Ikawa, Rajive Jassal, Vesna Jelic, Peter Johannsen, Edward S. Johnson, Mary M. Kenan, Bert-Jan Kerklaan, Benjamin Lam, Gabriel C. Léger, Gabriel Leonard, Emilie Lepage, Irene Litvan, Oscar L. Lopez, Ian R. A. Mackenzie, Mario Masellis, Fodi Massoud, Paige Moorhouse, John C. Morris, Taim Muayqil, Yannick Nadeau, Inger Nennesmo, Jørgen E. Nielsen, Ricardo Nitrini, Sven-Eric Pålhagen, Robert Perry, Gerald Pfeffer, Machiel Pleizier, Steffen Plickert, Gil D. Rabinovici, Philippe H. Robert, Lothar Resch, Gustavo C. Román, Maxime Ros, Pedro Rosa-Neto, Aiman Sanosi, Philip Scheltens, Christian Schmidt, Eric Schmidt, Jean-Paul Soucy, Jette Stokholm, David Summers, Rawan Tarawneh, Louis Verret, Huali Wang, Bengt Winblad, Makoto Yoneda, Xin Yu, Inga Zerr
- Edited by Serge Gauthier, McGill University, Montréal, Pedro Rosa-Neto, McGill University, Montréal
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- Book:
- Case Studies in Dementia
- Published online:
- 16 May 2011
- Print publication:
- 21 April 2011, pp viii-xiv
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North American Labor History Conference
- Eric Fure-Slocum, Kim Nielsen, Dorsey Phelps, Anthony Quiroz, Mark Stemen, Paul Young
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- Journal:
- International Labor and Working-Class History / Volume 46 / Fall 1994
- Published online by Cambridge University Press:
- 16 December 2008, pp. 173-176
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Simulating Extrasolar Planet Populations for Direct Imaging Surveys
- Eric L. Nielsen, L. M. Close, B. A. Biller
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- Journal:
- Proceedings of the International Astronomical Union / Volume 1 / Issue C200 / October 2005
- Published online by Cambridge University Press:
- 02 May 2006, pp. 111-118
- Print publication:
- October 2005
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As high contrast imaging surveys are being designed and carried out to directly detect extrasolar planets around young, nearby stars it is important to carefully evaluate the criteria for selection of target stars, as well as the predicted success of such a survey based on the sensitivity of the AO system used. We have developed a routine to simulate a large number of planets around each potential target star, and determine what fraction can be reliably (5$\sigma$) detected using an AO system's predicted or observed sensitivity curve (the maximum flux ratio between the parent star and a detectable planet as a function of projected radius). Each planet has a randomly assigned semi-major axis, mass, and eccentricity (following extrapolations of detected radial velocity planet power laws), as well as random viewing angles and orbital phase. The orbital parameters give a projected separation for each planet, while the mass is converted into a flux ratio in the appropriate bandpass of the detector using the models of Burrows et al. (2003); this allows the simulated planets to be directly evaluated against the system's sensitivity curve. Since this method requires basic parameters (age, distance, spectral type, apparent magnitude) for each target star, a target list can be constructed that maximizes the likelihood of detecting planets, or competing instrument designs can be evaluated with respect to their predicted success for a given survey. We are already employing this method to select targets for our Simultaneous Differential Imaging (SDI) surveys (Biller et al. 2004), now underway at telescopes in the northern (MMT) and southern hemispheres (VLT).
Suppressing Speckle Noise for Simultaneous Differential Extrasolar Planet Imaging (SDI) at the VLT and MMT
- Beth A. Biller, Laird M. Close, Rainer Lenzen, Wolfgang Brandner, Donald McCarthy, Eric Nielsen, Stephan Kellner, Markus Hartung
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- Journal:
- Proceedings of the International Astronomical Union / Volume 1 / Issue C200 / October 2005
- Published online by Cambridge University Press:
- 02 May 2006, pp. 571-576
- Print publication:
- October 2005
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We discuss the instrumental and data reduction techniques used to suppress speckle noise with the Simultaneous Differential Imager (SDI) implemented at the VLT and the MMT. SDI uses a quad filter to take images simultaneously at 3 wavelengths surrounding the 1.62 $\mu$m methane bandhead found in the spectrum of cool brown dwarfs and gas giants. By performing a difference of images in these filters, speckle noise from the primary can be significantly attenuated, resulting in photon noise limited data. Non-trivial data reduction tools are necessary to pipeline the simultaneous differential imaging. Here we discuss a custom algorithm implemented in IDL to perform this reduction. The script performs basic data reduction tasks but also precisely aligns images taken in each of the filters using a custom shift and subtract routine. In our survey of nearby young stars at the VLT and MMT (see Biller et al., this conference), we achieved H band contrasts >25000 (5$\sigma \Delta$F1(1.575 $\mu$m) >10.0 mag, $\Delta$H$\,{>}\,$11.5 mag for a T6 spectral type object) at a separation of 0.5” from the primary star. We believe that our SDI images are among the highest contrast astronomical images ever made from ground or space for methane rich companions.
A Survey of Close, Young Stars with SDI at the VLT and MMT
- Beth A. Biller, Laird M. Close, Elena Masciadri, Rainer Lenzen, Wolfgang Brandner, Donald McCarthy, Thomas Henning, Eric Nielsen, Markus Hartung
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- Journal:
- Proceedings of the International Astronomical Union / Volume 1 / Issue C200 / October 2005
- Published online by Cambridge University Press:
- 02 May 2006, pp. 53-60
- Print publication:
- October 2005
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We discuss the preliminary results of a survey of young ($<$300 Myr), close ($<$50 pc) stars with the Simultaneous Differential Extrasolar Planet Imager (SDI) implemented at the VLT and the MMT. SDI uses a quad filter to take images simultaneously at 3 wavelengths surrounding the 1.62 $\mu$m methane bandhead found in the spectrum of cool brown dwarfs and gas giants. By performing a difference of images in these filters, speckle noise from the primary can be significantly attenuated, resulting in photon noise limited data. In our survey data, we achieved H band contrasts $>$25000 (5$\sigma \Delta$F1(1.575$\mu$m)$>$10 mag, $\Delta$H$>$11.5 mag for a T6 spectral type) at a separation of 0.5” from the primary star. With this degree of attenuation, we should be able to image (5$\sigma$ detection) a 2-4 Jupiter mass planet at 5 AU around a 30 Myr star at 10 pc. We are currently completing our survey of young, nearby stars, with complete datasets for 35 stars in the southern sky (VLT) and 7 stars in the northern sky (MMT). We believe that our SDI images are the highest contrast astronomical images ever made from ground or space for methane rich companions.
Group I-like ribozymes with a novel core organization perform obligate sequential hydrolytic cleavages at two processing sites
- CHRISTER EINVIK, HENRIK NIELSEN, ERIC WESTHOF, FRANÇOIS MICHEL, STEINAR JOHANSEN
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A new category of self-splicing group I introns with conserved structural organization and function is found among the eukaryotic microorganisms Didymium and Naegleria. These complex rDNA introns contain two distinct ribozymes with different functions: a regular group I splicing-ribozyme and a small internal group I-like ribozyme (GIR1), probably involved in protein expression. GIR1 was found to cleave at two internal sites in an obligate sequential order. Both sites are located 3′ of the catalytic core. GIR1-catalyzed transesterification reactions could not be detected. We have compared all available GIR1 sequences and propose a common RNA secondary structure resembling that of group I splicing-ribozymes, but with some important differences. The GIR1s lack most peripheral sequence components, as well as a P1 segment, and, at approximately 160–190 nt, they are the smallest functional group I ribozymes known from nature. All GIR1s were found to contain a novel 6-bp pseudoknot (P15) within their catalytic core region. Experimental support of the proposed structure was obtained from the Didymium GIR1 by RNA structure probing and site-directed mutagenesis. Three-dimensional modeling indicates a compactly folded ribozyme with the functionally essential P15 exposed in the cleft between the two principal domains P3–P8 and P4–P6.