4 results
Unexpected circular radio objects at high Galactic latitude
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- Ray P. Norris, Huib T. Intema, Anna D. Kapińska, Bärbel S. Koribalski, Emil Lenc, L. Rudnick, Rami Z. E. Alsaberi, Craig Anderson, G. E. Anderson, E. Crawford, Roland Crocker, Jayanne English, Miroslav D. Filipović, Tim J. Galvin, Andrew M. Hopkins, Natasha Hurley-Walker, Susumu Inoue, Kieran Luken, Peter J. Macgregor, Pero Manojlović, Josh Marvil, Andrew N. O’Brien, Laurence Park, Wasim Raja, Devika Shobhana, Tiziana Venturi, Jordan D. Collier, Catherine Hale, Aidan Hotan, Vanessa Moss, Matthew Whiting
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- Journal:
- Publications of the Astronomical Society of Australia / Volume 38 / 2021
- Published online by Cambridge University Press:
- 18 January 2021, e003
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We have found a class of circular radio objects in the Evolutionary Map of the Universe Pilot Survey, using the Australian Square Kilometre Array Pathfinder telescope. The objects appear in radio images as circular edge-brightened discs, about one arcmin diameter, that are unlike other objects previously reported in the literature. We explore several possible mechanisms that might cause these objects, but none seems to be a compelling explanation.
Streams and the Milky Way dark matter halo
- Heidi Jo Newberg, Siddhartha Shelton, Eric Mendelsohn, Jake Weiss, Matthew Arsenault, Jacob S. Bauer, Travis Desell, Roland Judd, Malik Magdon-Ismail, Lee A. Newberg, Matthew Newby, Clayton Rayment, Colin Rice, Boleslaw K. Szymanski, Jeffery M. Thompson, Steve Ulin, Carlos Varela, Lawrence M. Widrow, Benjamin A. Willett
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- Journal:
- Proceedings of the International Astronomical Union / Volume 14 / Issue S353 / June 2019
- Published online by Cambridge University Press:
- 14 May 2020, pp. 75-82
- Print publication:
- June 2019
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We describe an algorithm that can fit the properties of the dwarf galaxy progenitor of a tidal stream, given the properties of that stream. We show that under ideal conditions (the Milky Way potential, the orbit of the dwarf galaxy progenitor, and the functional form of the dwarf galaxy progenitor are known exactly), the density and angular width of stars along the stream can be used to constrain the mass and radial profile of both the stellar and dark matter components of the progenitor dwarf galaxy that was ripped apart to create the stream. Our provisional fit for the parameters of the dwarf galaxy progenitor of the Orphan Stream indicates that it is less massive and has fewer stars than previous works have indicated.
Contributors
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- By Aakash Agarwala, Linda S. Aglio, Rae M. Allain, Paul D. Allen, Houman Amirfarzan, Yasodananda Kumar Areti, Amit Asopa, Edwin G. Avery, Patricia R. Bachiller, Angela M. Bader, Rana Badr, Sibinka Bajic, David J. Baker, Sheila R. Barnett, Rena Beckerly, Lorenzo Berra, Walter Bethune, Sascha S. Beutler, Tarun Bhalla, Edward A. Bittner, Jonathan D. Bloom, Alina V. Bodas, Lina M. Bolanos-Diaz, Ruma R. Bose, Jan Boublik, John P. Broadnax, Jason C. Brookman, Meredith R. Brooks, Roland Brusseau, Ethan O. Bryson, Linda A. Bulich, Kenji Butterfield, William R. Camann, Denise M. Chan, Theresa S. Chang, Jonathan E. Charnin, Mark Chrostowski, Fred Cobey, Adam B. Collins, Mercedes A. Concepcion, Christopher W. Connor, Bronwyn Cooper, Jeffrey B. Cooper, Martha Cordoba-Amorocho, Stephen B. Corn, Darin J. Correll, Gregory J. Crosby, Lisa J. Crossley, Deborah J. Culley, Tomas Cvrk, Michael N. D'Ambra, Michael Decker, Daniel F. Dedrick, Mark Dershwitz, Francis X. Dillon, Pradeep Dinakar, Alimorad G. Djalali, D. John Doyle, Lambertus Drop, Ian F. Dunn, Theodore E. Dushane, Sunil Eappen, Thomas Edrich, Jesse M. Ehrenfeld, Jason M. Erlich, Lucinda L. Everett, Elliott S. Farber, Khaldoun Faris, Eddy M. Feliz, Massimo Ferrigno, Richard S. Field, Michael G. Fitzsimons, Hugh L. Flanagan Jr., Vladimir Formanek, Amanda A. Fox, John A. Fox, Gyorgy Frendl, Tanja S. Frey, Samuel M. Galvagno Jr., Edward R. Garcia, Jonathan D. Gates, Cosmin Gauran, Brian J. Gelfand, Simon Gelman, Alexander C. Gerhart, Peter Gerner, Omid Ghalambor, Christopher J. Gilligan, Christian D. Gonzalez, Noah E. Gordon, William B. Gormley, Thomas J. Graetz, Wendy L. Gross, Amit Gupta, James P. Hardy, Seetharaman Hariharan, Miriam Harnett, Philip M. Hartigan, Joaquim M. Havens, Bishr Haydar, Stephen O. Heard, James L. Helstrom, David L. Hepner, McCallum R. Hoyt, Robert N. Jamison, Karinne Jervis, Stephanie B. Jones, Swaminathan Karthik, Richard M. Kaufman, Shubjeet Kaur, Lee A. Kearse Jr., John C. Keel, Scott D. Kelley, Albert H. Kim, Amy L. Kim, Grace Y. Kim, Robert J. Klickovich, Robert M. Knapp, Bhavani S. Kodali, Rahul Koka, Alina Lazar, Laura H. Leduc, Stanley Leeson, Lisa R. Leffert, Scott A. LeGrand, Patricio Leyton, J. Lance Lichtor, John Lin, Alvaro A. Macias, Karan Madan, Sohail K. Mahboobi, Devi Mahendran, Christine Mai, Sayeed Malek, S. Rao Mallampati, Thomas J. Mancuso, Ramon Martin, Matthew C. Martinez, J. A. Jeevendra Martyn, Kai Matthes, Tommaso Mauri, Mary Ellen McCann, Shannon S. McKenna, Dennis J. McNicholl, Abdel-Kader Mehio, Thor C. Milland, Tonya L. K. Miller, John D. Mitchell, K. Annette Mizuguchi, Naila Moghul, David R. Moss, Ross J. Musumeci, Naveen Nathan, Ju-Mei Ng, Liem C. Nguyen, Ervant Nishanian, Martina Nowak, Ala Nozari, Michael Nurok, Arti Ori, Rafael A. Ortega, Amy J. Ortman, David Oxman, Arvind Palanisamy, Carlo Pancaro, Lisbeth Lopez Pappas, Benjamin Parish, Samuel Park, Deborah S. Pederson, Beverly K. Philip, James H. Philip, Silvia Pivi, Stephen D. Pratt, Douglas E. Raines, Stephen L. Ratcliff, James P. Rathmell, J. Taylor Reed, Elizabeth M. Rickerson, Selwyn O. Rogers Jr., Thomas M. Romanelli, William H. Rosenblatt, Carl E. Rosow, Edgar L. Ross, J. Victor Ryckman, Mônica M. Sá Rêgo, Nicholas Sadovnikoff, Warren S. Sandberg, Annette Y. Schure, B. Scott Segal, Navil F. Sethna, Swapneel K. Shah, Shaheen F. Shaikh, Fred E. Shapiro, Torin D. Shear, Prem S. Shekar, Stanton K. Shernan, Naomi Shimizu, Douglas C. Shook, Kamal K. Sikka, Pankaj K. Sikka, David A. Silver, Jeffrey H. Silverstein, Emily A. Singer, Ken Solt, Spiro G. Spanakis, Wolfgang Steudel, Matthias Stopfkuchen-Evans, Michael P. Storey, Gary R. Strichartz, Balachundhar Subramaniam, Wariya Sukhupragarn, John Summers, Shine Sun, Eswar Sundar, Sugantha Sundar, Neelakantan Sunder, Faraz Syed, Usha B. Tedrow, Nelson L. Thaemert, George P. Topulos, Lawrence C. Tsen, Richard D. Urman, Charles A. Vacanti, Francis X. Vacanti, Joshua C. Vacanti, Assia Valovska, Ivan T. Valovski, Mary Ann Vann, Susan Vassallo, Anasuya Vasudevan, Kamen V. Vlassakov, Gian Paolo Volpato, Essi M. Vulli, J. Matthias Walz, Jingping Wang, James F. Watkins, Maxwell Weinmann, Sharon L. Wetherall, Mallory Williams, Sarah H. Wiser, Zhiling Xiong, Warren M. Zapol, Jie Zhou
- Edited by Charles Vacanti, Scott Segal, Pankaj Sikka, Richard Urman
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- Book:
- Essential Clinical Anesthesia
- Published online:
- 05 January 2012
- Print publication:
- 11 July 2011, pp xv-xxviii
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Development of Bone-Lead Reference Materials for Validating In Vivo Xrf Measurements
- Patrick J. Parsons, Yan Y. Zong, M. Roland Matthews
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- Journal:
- Advances in X-ray Analysis / Volume 38 / 1994
- Published online by Cambridge University Press:
- 06 March 2019, pp. 625-632
- Print publication:
- 1994
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A number of biological reference materials (RM) have been prepared in our laboratory specifically for validating analytical methods for the determination of Pb in biological matrices (e.g. blood, urine, liver, and bone). The RM's were developed using animal (goats and cows) that are routinely dosed with lead acetate to produce proficiency test samples for blood lead (and erythrocyte protoporphyrin). In cases where an animal becomes injured or infirm, the veterinarian in charge may recommend that the animal be euthanized. In such cases, samples of bone, brain, liver, and other tissues containing lead are removed at autopsy.
Currently, we have collected bone samples from nine goats and one cow that were dosed with lead over periods ranging from 1 to 10 years, During the autopsy, the epiphyses (bone joints) are separated from each long bone. Skin, muscle, and other adhering tissues are dissected or scraped from each bone. Bone marrow is also removed. All bare bones are currently stored at -70°C until analyses for Pb are conducted.
The only certified reference materials for bone Pb are those available from the National Institute for Standards and Technology (NIST), Gaithersburg, MD. Standard Reference Material (SRM) 1486 Bone Meal has a certified Pb concentration of only 1.335 μg/g. This is close to normal for humans, but is too low to be of practical use for in vivo X-Ray Fluorescence (XRF) equipment, SRM 1400 Bone Ash has a certified Pb concentration of 9.07 μg/g. Neither SRM is optimal for validating in vivo XRF equipment, but they are both very useful in validating other analytical methods for bone Pb such as Graphite Furnace Atomic Absorption Spectrometry (GFAAS).
We have developed an accurate, precise, and sensitive method for determining Pb in bone using GFAAS with Zeeman background correction. Using this method, we have analyzed the animal bones for Pb. Bone samples were divided into smaller pieces using a diamond-disc saw, freeze dried, and homogenized in a tantalum ball mill. Samples of bone powder were digested in nitric acid using a closed vessel microwave digestion system. Lead was determined using aqueous Pb standards in a chemical modifier optimized for the bone matrix. The method was validated using NIST SRM Bone Meal and Bone Ash. The detection limit is 0.6 μg/g based on 3 SD. Results for Pb in our animal bone range from approximately 5 to 50 μg/g dry weight. The results indicate that the intact bare bones would be excellent candidates for interlaboratory studies of in vivo XRF measurements of bone Pb. They are stable, well-characterized, easily transported between sites, and cover the clinically relevant range of bone lead concentrations likely to be encountered in the field. It is proposed that these materials be circulated as part of an interlaboratory comparison to interested centers using in vivo XRF After the XRF analyses, the bone samples will be analyzed for Pb by GFAAS for comparison purposes.