3,055 results on '"Kramer, Michael"'
Search Results
2. Social Determinants of Health Needs and Perinatal Risk in Socially Vulnerable Pregnant Patients
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Joseph, Naima T., Stanhope, Kaitlyn K., Geary, Franklyn, McIntosh, Michelle, Platner, Marissa H., Wichmann, Hannah K., Kramer, Michael R., Jamieson, Denise J., and Boulet, Sheree L.
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- 2023
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3. First Very Long Baseline Interferometry Detections at 870{\mu}m
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Raymond, Alexander W., Doeleman, Sheperd S., Asada, Keiichi, Blackburn, Lindy, Bower, Geoffrey C., Bremer, Michael, Broguiere, Dominique, Chen, Ming-Tang, Crew, Geoffrey B., Dornbusch, Sven, Fish, Vincent L., García, Roberto, Gentaz, Olivier, Goddi, Ciriaco, Han, Chih-Chiang, Hecht, Michael H., Huang, Yau-De, Janssen, Michael, Keating, Garrett K., Koay, Jun Yi, Krichbaum, Thomas P., Lo, Wen-Ping, Matsushita, Satoki, Matthews, Lynn D., Moran, James M., Norton, Timothy J., Patel, Nimesh, Pesce, Dominic W., Ramakrishnan, Venkatessh, Rottmann, Helge, Roy, Alan L., Sánchez, Salvador, Tilanus, Remo P. J., Titus, Michael, Torne, Pablo, Wagner, Jan, Weintroub, Jonathan, Wielgus, Maciek, Young, André, Akiyama, Kazunori, Albentosa-Ruíz, Ezequiel, Alberdi, Antxon, Alef, Walter, Algaba, Juan Carlos, Anantua, Richard, Azulay, Rebecca, Bach, Uwe, Baczko, Anne-Kathrin, Ball, David, Baloković, Mislav, Bandyopadhyay, Bidisha, Barrett, John, Bauböck, Michi, Benson, Bradford A., Bintley, Dan, Blundell, Raymond, Bouman, Katherine L., Boyce, Hope, Brissenden, Roger, Britzen, Silke, Broderick, Avery E., Bronzwaer, Thomas, Bustamante, Sandra, Carlstrom, John E., Chael, Andrew, Chan, Chi-kwan, Chang, Dominic O., Chatterjee, Koushik, Chatterjee, Shami, Chen, Yongjun, Cheng, Xiaopeng, Cho, Ilje, Christian, Pierre, Conroy, Nicholas S., Conway, John E., Crawford, Thomas M., Cruz-Osorio, Alejandro, Cui, Yuzhu, Dahale, Rohan, Davelaar, Jordy, De Laurentis, Mariafelicia, Deane, Roger, Dempsey, Jessica, Desvignes, Gregory, Dexter, Jason, Dhruv, Vedant, Dihingia, Indu K., Dzib, Sergio A., Eatough, Ralph P., Emami, Razieh, Falcke, Heino, Farah, Joseph, Fomalont, Edward, Fontana, Anne-Laure, Ford, H. Alyson, Foschi, Marianna, Fraga-Encinas, Raquel, Freeman, William T., Friberg, Per, Fromm, Christian M., Fuentes, Antonio, Galison, Peter, Gammie, Charles F., Georgiev, Boris, Gold, Roman, Gómez-Ruiz, Arturo I., Gómez, José L., Gu, Minfeng, Gurwell, Mark, Hada, Kazuhiro, Haggard, Daryl, Hesper, Ronald, Heumann, Dirk, Ho, Luis C., Ho, Paul, Honma, Mareki, Huang, Chih-Wei L., Huang, Lei, Hughes, David H., Ikeda, Shiro, Impellizzeri, C. M. Violette, Inoue, Makoto, Issaoun, Sara, James, David J., Jannuzi, Buell T., Jeter, Britton, Jiang, Wu, Jiménez-Rosales, Alejandra, Johnson, Michael D., Jorstad, Svetlana, Jones, Adam C., Joshi, Abhishek V., Jung, Taehyun, Karuppusamy, Ramesh, Kawashima, Tomohisa, Kettenis, Mark, Kim, Dong-Jin, Kim, Jae-Young, Kim, Jongsoo, Kim, Junhan, Kino, Motoki, Kocherlakota, Prashant, Kofuji, Yutaro, Koch, Patrick M., Koyama, Shoko, Kramer, Carsten, Kramer, Joana A., Kramer, Michael, Kubo, Derek, Kuo, Cheng-Yu, La Bella, Noemi, Lee, Sang-Sung, Levis, Aviad, Li, Zhiyuan, Lico, Rocco, Lindahl, Greg, Lindqvist, Michael, Lisakov, Mikhail, Liu, Jun, Liu, Kuo, Liuzzo, Elisabetta, Lobanov, Andrei P., Loinard, Laurent, Lonsdale, Colin J., Lowitz, Amy E., Lu, Ru-Sen, MacDonald, Nicholas R., Mahieu, Sylvain, Maier, Doris, Mao, Jirong, Marchili, Nicola, Markoff, Sera, Marrone, Daniel P., Marscher, Alan P., Martí-Vidal, Iván, Medeiros, Lia, Menten, Karl M., Mizuno, Izumi, Mizuno, Yosuke, Montgomery, Joshua, Moriyama, Kotaro, Moscibrodzka, Monika, Mulaudzi, Wanga, Müller, Cornelia, Müller, Hendrik, Mus, Alejandro, Musoke, Gibwa, Myserlis, Ioannis, Nagai, Hiroshi, Nagar, Neil M., Nakamura, Masanori, Narayanan, Gopal, Natarajan, Iniyan, Nathanail, Antonios, Fuentes, Santiago Navarro, Neilsen, Joey, Ni, Chunchong, Nowak, Michael A., Oh, Junghwan, Okino, Hiroki, Sánchez, Héctor Raúl Olivares, Oyama, Tomoaki, Özel, Feryal, Palumbo, Daniel C. M., Paraschos, Georgios Filippos, Park, Jongho, Parsons, Harriet, Pen, Ue-Li, Piétu, Vincent, PopStefanija, Aleksandar, Porth, Oliver, Prather, Ben, Principe, Giacomo, Psaltis, Dimitrios, Pu, Hung-Yi, Raffin, Philippe A., Rao, Ramprasad, Rawlings, Mark G., Ricarte, Angelo, Ripperda, Bart, Roelofs, Freek, Romero-Cañizales, Cristina, Ros, Eduardo, Roshanineshat, Arash, Ruiz, Ignacio, Ruszczyk, Chet, Rygl, Kazi L. J., Sánchez-Argüelles, David, Sánchez-Portal, Miguel, Sasada, Mahito, Satapathy, Kaushik, Savolainen, Tuomas, Schloerb, F. Peter, Schonfeld, Jonathan, Schuster, Karl-Friedrich, Shao, Lijing, Shen, Zhiqiang, Small, Des, Sohn, Bong Won, SooHoo, Jason, Salas, León David Sosapanta, Souccar, Kamal, Srinivasan, Ranjani, Stanway, Joshua S., Sun, He, Tazaki, Fumie, Tetarenko, Alexandra J., Tiede, Paul, Toma, Kenji, Toscano, Teresa, Traianou, Efthalia, Trent, Tyler, Trippe, Sascha, Turk, Matthew, van Bemmel, Ilse, van Langevelde, Huib Jan, van Rossum, Daniel R., Vos, Jesse, Ward-Thompson, Derek, Wardle, John, Washington, Jasmin E., Wharton, Robert, Wiik, Kaj, Witzel, Gunther, Wondrak, Michael F., Wong, George N., Wu, Qingwen, Yadlapalli, Nitika, Yamaguchi, Paul, Yfantis, Aristomenis, Yoon, Doosoo, Younsi, Ziri, Yu, Wei, Yuan, Feng, Yuan, Ye-Fei, Zensus, J. Anton, Zhang, Shuo, Zhao, Guang-Yao, and Zhao, Shan-Shan
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Astrophysics - Instrumentation and Methods for Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
The first very long baseline interferometry (VLBI) detections at 870$\mu$m wavelength (345$\,$GHz frequency) are reported, achieving the highest diffraction-limited angular resolution yet obtained from the surface of the Earth, and the highest-frequency example of the VLBI technique to date. These include strong detections for multiple sources observed on inter-continental baselines between telescopes in Chile, Hawaii, and Spain, obtained during observations in October 2018. The longest-baseline detections approach 11$\,$G$\lambda$ corresponding to an angular resolution, or fringe spacing, of 19$\mu$as. The Allan deviation of the visibility phase at 870$\mu$m is comparable to that at 1.3$\,$mm on the relevant integration time scales between 2 and 100$\,$s. The detections confirm that the sensitivity and signal chain stability of stations in the Event Horizon Telescope (EHT) array are suitable for VLBI observations at 870$\mu$m. Operation at this short wavelength, combined with anticipated enhancements of the EHT, will lead to a unique high angular resolution instrument for black hole studies, capable of resolving the event horizons of supermassive black holes in both space and time., Comment: Corresponding author: S. Doeleman
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- 2024
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4. Periodicity search in the timing of the 25 millisecond pulsars from the second data release of the European Pulsar Timing Array
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Nitu, Iuliana, Keith, Michael, Champion, David, Cognard, Ismael, Desvignes, Gregory, Guillemot, Lucas, Guo, Yanjun, Hu, Huanchen, Jang, Jiwoong, Jawor, Jedrzej, Karuppusamy, Ramesh, Keane, Evan, Kramer, Michael, Lackeos, Kristen, Liu, Kuo, Main, Robert, Perrodin, Delphine, Porayko, Nataliya, Shaifullah, Golam, and Theureau, Gilles
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
In this work, we investigated the presence of strictly periodic, as well as quasi-periodic signals, in the timing of the 25 millisecond pulsars from the EPTA DR2 dataset. This is especially interesting in the context of the recent hints of a gravitational wave background in these data, and the necessary further study of red-noise timing processes, which are known to behave quasi-periodically in some normal pulsars. We used Bayesian timing models developed through the run_enterprise pipeline: a strict periodicity was modelled as the influence of a planetary companion on the pulsar, while a quasi-periodicity was represented as a Fourier-domain Gaussian process. We found that neither model would clearly improve the timing models of the 25 millisecond pulsars in this dataset. This implies that noise and parameter estimates are unlikely to be biased by the presence of a (quasi-)periodicity in the timing data. Nevertheless, the results for PSRs J1744--1134 and J1012+5307 suggest that the standard noise models for these pulsars may not be sufficient. We also measure upper limits for the projected masses of planetary companions around each of the 25 pulsars. The data of PSR J1909--3744 yielded the best mass limits, such that we constrained the 95-percentile to 2*10^{-4} Earth-masses (roughly the mass of the dwarf planet Ceres) for orbital periods between 5 d--17 yr. These are the best pulsar planet mass limits to date., Comment: Submitted for publication in MNRAS
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- 2024
5. Pollinating Red19 - the right males in the right place
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Max, William and Kramer, Michael
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- 2023
6. PSR J1227$-$6208 and its massive white dwarf companion: pulsar emission analysis, timing update and mass measurements
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Bernadich, Miquel Colom i, Krishnan, Vivek Venkatraman, Champion, David J., Freire, Paulo C. C., Kramer, Michael, Tauris, Thomas M., Bailes, Matthew, Ridolfi, Alessandro, and Serylak, Maciej
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
PSR J1227$-$6208 is a 34.53-ms recycled pulsar with a massive companion. This system has long been suspected to belong to the emerging class of massive recycled pulsar-ONeMg white dwarf systems such as PSR J2222$-$0137, PSR J1528$-$3146 and J1439$-$5501. Here we present an updated emission and timing analysis with more than 11 years of combined Parkes and MeerKAT data, including 19 hours of high-frequency data from the newly installed MeerKAT S-band receivers. We measure a scattering timescale of 1.22 ms at 1 GHz with a flat scattering index 3.33<$\beta$<3.62, and a mean flux density of 0.53-0.62 mJy at 1 GHz with a steep spectral index 2.06<$\alpha$<2.35. Around 15% of the emission is linearly and circularly polarised, but the polarisation angle does not follow the rotating vector model. Thanks to the sensitivity of MeerKAT, we successfully measure a rate of periastron advance of 0.0171(11) deg/yr, and a Shapiro delay with an orthometric amplitude of 3.6$\pm$0.5 $\mu$s and an orthometric shape of 0.85$\pm$0.05. The main source of uncertainty in our timing analysis is chromatic correlated dispersion measure noise, which we model as a power law in the Fourier space thanks to the large frequency coverage provided by the Parkes UWL receiver. Assuming general relativity and accounting for the measurements across all the implemented timing noise models, the total mass, companion mass, pulsar mass and inclination angle are constrained at 2.3
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- 2024
7. The SKA Galactic Centre Survey -- A White Paper
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Schoedel, Rainer, Alberdi, Antxon, Jimenez-Serra, Izaskun, Yusef-Zadeh, Farhad, Gardini, Angela, Kramer, Michael, Torres, Miguel Perez, Morris, Mark R., Forbrich, Jan, Ingallinera, Adriano, Nogueras-Lara, Francisco, Henshaw, Jonathan D., Longmore, Steven N., Moldon, Javier, Heywood, Ian, Rammala, Isabella, Montenegro, Lourdes Verdes, and Exposito, Susana Sanchez
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Astrophysics - Astrophysics of Galaxies - Abstract
With its extreme density of stars and stellar remnants, dense young massive clusters, high specific star formation rate, intense radiation field, high magnetic field strength, and properties of the interstellar medium that resemble those in high redshift galaxies and starbursts, the Galactic Centre is the most extreme environment that we can observe in detail. It is also the only nucleus of a galaxy that we can observe with a resolution of just a few milli parsecs. This makes it a crucial target to understand the physics of galactic nuclei and star formation, as well as the connection between them. It enables studies of a large number of otherwise rare objects, such as extremely massive stars and stellar remnants, at a well-defined distance, thus facilitating the interpretation of their properties. The Galactic Centre has been and is being studied intensively with the most advanced facilities. In this White Paper, we advocate for a large-area, multi-wavelength survey with the Square Kilometre Array of an area of about 1.25x0.3 deg**2 (180x40 pc**2), centered on the massive black hole Sagittarius A* and for repeated deep observations of the nuclear star cluster over a decade, which will allow the community to address multiple science problems with a single data set.
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- 2024
8. The Cambridge History of Jewish American Literature: Three Prequels
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Kramer, Michael P.
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- 2018
9. The Relativistic Spin Precession in the Compact Double Neutron Star System PSR~J1946+2052
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Meng, Lingqi, Zhu, Weiwei, Kramer, Michael, Miao, Xueli, Desvignes, Gregory, Shao, Lijing, Hu, Huanchen, Freire, Paulo C. C., Zhang, Yongkun, Xue, Mengyao, Fang, Ziyao, Champion, David J., Yuan, Mao, Miao, Chenchen, Niu, Jiarui, Fu, Qiuyang, Yao, Jumei, Guo, Yanjun, and Zhang, Chengmin
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
We observe systematic profile changes in the visible pulsar of the compact double neutron star system PSR~J1946+2052 using observations with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The interpulse of PSR~J1946+2052 changed from single-peak to double-peak shape from 2018 to 2021. We attribute this evolution as the result of the relativistic spin precession of the pulsar. With the high sensitivity of FAST, we also measure significant polarization for the first time, allowing us to model this with the precessional rotating vector model. Assuming, to the first order, a circular hollow-cone-like emission beam pattern and taking the validity of general relativity, we derive the binary's orbital inclination angle (${63^\circ}^{+5^\circ}_{-3^\circ}$) and pulsar's spin geometry. Pulsar's spin vector and the orbital angular momentum vector are found to be only slightly misaligned (${0.21^\circ}^{+0.28^\circ}_{-0.10^\circ}$).The quoted uncertainties do not reflect the systematic uncertainties introduced by our model assumptions. By simulating future observations of profile and polarization evolution, we estimate that we could constrain the precession rate within a $43\%$ uncertainty in 9 years. Hence, we suggest that the system's profile evolution could be combined with precise pulsar timing to test general relativity in the future., Comment: 12 pages, 9 figures, accepted for publication in ApJ
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- 2024
10. Unpacking Breastfeeding Disparities: Baby-Friendly Hospital Designation Associated with Reduced In-Hospital Exclusive Breastfeeding Disparity Attributed to Neighborhood Poverty
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Bookhart, Larelle H., Anstey, Erica H., Kramer, Michael R., Perrine, Cria G., Ramakrishnan, Usha, and Young, Melissa F.
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- 2024
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11. Radio Pulse Profile Evolution of Magnetar Swift J1818.0-1607
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Fisher, Rebecca, Butterworth, Elliot, Rajwade, Kaustubh, Stappers, Ben, Desvignes, Gregory, Karuppusamy, Ramesh, Kramer, Michael, Liu, Kuo, Lyne, Andrew, Mickaliger, Mitchell, Shaw, Benjamin, and Weltevrede, Patrick
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
The shape and polarisation properties of the radio pulse profiles of radio-loud magnetars provide a unique opportunity to investigate their magnetospheric properties. Gaussian Process Regression analysis was used to investigate the variation in the total intensity shape of the radio pulse profiles of the magnetar Swift J1818.0-1607. The observed profile shape was found to evolve through three modes between MJDs 59104 and 59365. The times at which these transitions occurred coincided with changes in the amplitude of modulations in the spin-down rate. The amount of linear and circular polarisation was also found to vary significantly with time. Lomb-Scargle periodogram analysis of the spin-down rate revealed three possibly harmonically related frequencies. This could point to the magnetar experiencing seismic activity. However, no profile features exhibited significant periodicity, suggesting no simple correlations between the profile variability and fluctuations of the spin-down on shorter timescales within the modes. Overall, this implies the mode changes seen are a result of local magnetospheric changes, with other theories, such as precession, less able to explain these observations., Comment: 11 pages, 6 figures, accepted for publication in MNRAS
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- 2024
12. Quasi-periodic sub-pulse structure as a unifying feature for radio-emitting neutron stars
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Kramer, Michael, Liu, Kuo, Desvignes, Gregory, Karuppusamy, Ramesh, and Stappers, Ben W.
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
Magnetars are highly-magnetised rotating neutron stars that are predominantly observed as high-energy sources. Six of this class of neutron star are known to also emit radio emission, and magnetars are, thus, a favoured model for the origin for at least some of the Fast Radio Bursts (FRBs). If magnetars, or neutron stars in general, are indeed responsible, sharp empirical constraints on the mechanism producing radio emission are required. Here we report on the detection of polarised quasi-periodic sub-structure in the emission of all well-studied radio-detected magnetars. A correlation previously seen, relating sub-structure in pulsed emission of radio emitting neutron stars to their rotational period, is extended, and shown to now span more than six of orders of magnitude in pulse period. This behaviour is not only seen in magnetars but in members of all classes of radio-emitting rotating neutron stars, regardless of their evolutionary history, their power source or their inferred magnetic field strength. If magnetars are responsible for FRBs, it supports the idea of being able to infer underlying periods from sub-burst timescales in FRBs., Comment: published in Nature Astronomy, 48 pages (main text, methods, extended data figures & tables and supplementary information), in total 17 figures, 4 tables
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- 2023
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13. Reflective cloth in kiwifruit orchards - new questions and new developments
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Kramer, Michael
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- 2020
14. More than a Principal: Ubuntu at the Heart of Successful School Leadership in the Western Cape
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Kramer, Michael
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School leadership matters. After teachers and teaching, school leadership is the most important determinant of learner achievement in school. Despite this, there is still uncertainty regarding what successfulschool leadership is and what successful school leaders do in non-Western contexts. In this mixed methods study I explored successful high school leadership in South Africa. Specifically, a questionnaire was administered to 38 principals from academically high-achieving schools from a range of socioeconomic contexts throughout the Western Cape, and 14 principals were interviewed. An integrated analysis reveals the paradox of uniqueness and universality of successful school leadership in South Africa, outlining that while there is no single best approach, various similarities exist between successful school leaders and established international literature. I found that successful principals adapt to their context, amalgamate transformational, instructional and distributed leadership styles, set direction, develop people, constantly realign the school with teaching and learning, and, importantly, strive to make a difference in the lives of others. It is about leading with Ubuntu. By highlighting these characteristics and practices, I offer theoretical, practical and personal advice to current and aspiring school leaders, academics and policy makers.
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- 2023
15. A freely precessing magnetar following an X-ray outburst
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Desvignes, Gregory, Weltevrede, Patrick, Gao, Yong, Jones, David Ian, Kramer, Michael, Caleb, Manisha, Karuppusamy, Ramesh, Levin, Lina, Liu, Kuo, Lyne, Andrew G., Shao, Lijing, Stappers, Ben, and Pétri, Jérôme
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- 2024
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16. A search for pulsars around Sgr A* in the first Event Horizon Telescope dataset
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Torne, Pablo, Liu, Kuo, Eatough, Ralph P., Wongphechauxsorn, Jompoj, Cordes, James M., Desvignes, Gregory, De Laurentis, Mariafelicia, Kramer, Michael, Ransom, Scott M., Chatterjee, Shami, Wharton, Robert, Karuppusamy, Ramesh, Blackburn, Lindy, Janssen, Michael, Chan, Chi-kwan, Crew, Geoffrey B., Matthews, Lynn D., Goddi, Ciriaco, Rottmann, Helge, Wagner, Jan, Sanchez, Salvador, Ruiz, Ignacio, Abbate, Federico, Bower, Geoffrey C., Salamanca, Juan J., Gomez-Ruiz, Arturo I., Herrera-Aguilar, Alfredo, Jiang, Wu, Lu, Ru-Sen, Pen, Ue-Li, Raymond, Alexander W., Shao, Lijing, Shen, Zhiqiang, Paubert, Gabriel, Sanchez-Portal, Miguel, Kramer, Carsten, Castillo, Manuel, Navarro, Santiago, John, David, Schuster, Karl-Friedrich, Johnson, Michael D., Rygl, Kazi L. J., Akiyama, Kazunori, Alberdi, Antxon, Alef, Walter, Algaba, Juan Carlos, Anantua, Richard, Asada, Keiichi, Azulay, Rebecca, Bach, Uwe, Baczko, Anne-Kathrin, Ball, David, Balokovic, Mislav, Barrett, John, Bauboeck, Michi, Benson, Bradford A., Bintley, Dan, Blundell, Raymond, Bouman, Katherine L., Boyce, Hope, Bremer, Michael, Brinkerink, Christiaan D., Brissenden, Roger, Britzen, Silke, Broderick, Avery E., Broguiere, Dominique, Bronzwaer, Thomas, Bustamante, Sandra, Byun, Do-Young, Carlstrom, John E., Ceccobello, Chiara, Chael, Andrew, Chang, Dominic O., Chatterjee, Koushik, Chen, Ming-Tang, Chen, Yongjun, Cheng, Xiaopeng, Cho, Ilje, Christian, Pierre, Conroy, Nicholas S., Conway, John E., Crawford, Thomas M., Cruz-Osorio, Alejandro, Cui, Yuzhu, Dahale, Rohan, Davelaar, Jordy, Deane, Roger, Dempsey, Jessica, Dexter, Jason, Dhruv, Vedant, Doeleman, Sheperd S., Dougal, Sean, Dzib, Sergio A., Emami, Razieh, Falcke, Heino, Farah, Joseph, Fish, Vincent L., Fomalont, Ed, Ford, H. Alyson, Foschi, Marianna, Fraga-Encinas, Raquel, Freeman, William T., Friberg, Per, Fromm, Christian M., Fuentes, Antonio, Galison, Peter, Gammie, Charles F., Garcia, Roberto, Gentaz, Olivier, Georgiev, Boris, Gold, Roman, Gomez, Jose L., Gu, Minfeng, Gurwell, Mark, Hada, Kazuhiro, Haggard, Daryl, Haworth, Kari, Hecht, Michael H., Hesper, Ronald, Heumann, Dirk, Ho, Luis C., Ho, Paul, Honma, Mareki, Huang, Chih-Wei L., Huang, Lei, Hughes, David H., Ikeda, Shiro, Impellizzeri, C. M. Violette, Inoue, Makoto, Issaoun, Sara, James, David J., Jannuzi, Buell T., Jeter, Britton, Jimenez-Rosales, Alejandra, Jorstad, Svetlana, Joshi, Abhishek V., Jung, Taehyun, Karami, Mansour, Kawashima, Tomohisa, Keating, Garrett K., Kettenis, Mark, Kim, Dong-Jin, Kim, Jae-Young, Kim, Jongsoo, Kim, Junhan, Kino, Motoki, Koay, Jun Yi, Kocherlakota, Prashant, Kofuji, Yutaro, Koyama, Shoko, Krichbaum, Thomas P., Kuo, Cheng-Yu, La Bella, Noemi, Lauer, Tod R., Lee, Daeyoung, Lee, Sang-Sung, Leung, Po Kin, Levis, Aviad, Li, Zhiyuan, Lico, Rocco, Lindahl, Greg, Lindqvist, Michael, Lisakov, Mikhail, Liu, Jun, Liuzzo, Elisabetta, Lo, Wen-Ping, Lobanov, Andrei P., Loinard, Laurent, Lonsdale, Colin J., MacDonald, Nicholas R., Mao, Jirong, Marchili, Nicola, Markoff, Sera, Marrone, Daniel P., Marscher, Alan P., Marti-Vidal, Ivan, Matsushita, Satoki, Medeiros, Lia, Menten, Karl M., Michalik, Daniel, Mizuno, Izumi, Mizuno, Yosuke, Moran, James M., Moriyama, Kotaro, Moscibrodzka, Monika, Muller, Cornelia, Muller, Hendrik, Mus, Alejandro, Musoke, Gibwa, Myserlis, Ioannis, Nadolski, Andrew, Nagai, Hiroshi, Nagar, Neil M., Nakamura, Masanori, Narayan, Ramesh, Narayanan, Gopal, Natarajan, Iniyan, Nathanail, Antonios, Neilsen, Joey, Neri, Roberto, Ni, Chunchong, Noutsos, Aristeidis, Nowak, Michael A., Oh, Junghwan, Okino, Hiroki, Olivares, Hector, Ortiz-Leon, Gisela N., Oyama, Tomoaki, Ozel, Feryal, Palumbo, Daniel C. M., Paraschos, Georgios Filippos, Park, Jongho, Parsons, Harriet, Patel, Nimesh, Pesce, Dominic W., Pietu, Vincent, Plambeck, Richard, PopStefanija, Aleksandar, Porth, Oliver, Potzl, Felix M., Prather, Ben, Preciado-Lopez, Jorge A., Psaltis, Dimitrios, Pu, Hung-Yi, Ramakrishnan, Venkatessh, Rao, Ramprasad, Rawlings, Mark G., Rezzolla, Luciano, Ricarte, Angelo, Ripperda, Bart, Roelofs, Freek, Rogers, Alan, Ros, Eduardo, Romero-Cañizales, Cristina, Roshanineshat, Arash, Roy, Alan L., Ruszczyk, Chet, Sanchez-Arguelles, David, Sasada, Mahito, Satapathy, Kaushik, Savolainen, Tuomas, Schloerb, F. Peter, Schonfeld, Jonathan, Small, Des, Sohn, Bong Won, SooHoo, Jason, Souccar, Kamal, Sun, He, Tetarenko, Alexandra J., Tiede, Paul, Tilanus, Remo P. J., Titus, Michael, Toscano, Teresa, Traianou, Efthalia, Trent, Tyler, Trippe, Sascha, Turk, Matthew, van Bemmel, Ilse, van Langevelde, Huib Jan, van Rossum, Daniel R., Vos, Jesse, Ward-Thompson, Derek, Wardle, John, Weintroub, Jonathan, Wex, Norbert, Wielgus, Maciek, Wiik, Kaj, Witzel, Gunther, Wondrak, Michael F., Wong, George N., Wu, Qingwen, Yadlapalli, Nitika, Yamaguchi, Paul, Yfantis, Aristomenis, Yoon, Doosoo, Young, Andre, Young, Ken, Younsi, Ziri, Yu, Wei, Yuan, Feng, Yuan, Ye-Fei, Zensus, J. Anton, Zhang, Shuo, Zhao, Guang-Yao, and Zhao, Shan-Shan
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
The Event Horizon Telescope (EHT) observed in 2017 the supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), at a frequency of 228.1 GHz ($\lambda$=1.3 mm). The fundamental physics tests that even a single pulsar orbiting Sgr A* would enable motivate searching for pulsars in EHT datasets. The high observing frequency means that pulsars - which typically exhibit steep emission spectra - are expected to be very faint. However, it also negates pulse scattering, an effect that could hinder pulsar detections in the Galactic Center. Additionally, magnetars or a secondary inverse Compton emission could be stronger at millimeter wavelengths than at lower frequencies. We present a search for pulsars close to Sgr A* using the data from the three most-sensitive stations in the EHT 2017 campaign: the Atacama Large Millimeter/submillimeter Array, the Large Millimeter Telescope and the IRAM 30 m Telescope. We apply three detection methods based on Fourier-domain analysis, the Fast-Folding-Algorithm and single pulse search targeting both pulsars and burst-like transient emission; using the simultaneity of the observations to confirm potential candidates. No new pulsars or significant bursts were found. Being the first pulsar search ever carried out at such high radio frequencies, we detail our analysis methods and give a detailed estimation of the sensitivity of the search. We conclude that the EHT 2017 observations are only sensitive to a small fraction ($\lesssim$2.2%) of the pulsars that may exist close to Sgr A*, motivating further searches for fainter pulsars in the region., Comment: 33 pages, 7 figures, 6 Tables. Accepted for publication in ApJ
- Published
- 2023
17. Galactic Interstellar Scintillation Observed from Four Globular Cluster Pulsars by FAST
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Zhang, Dandan, Tao, Zhenzhao, Yuan, Mao, Yao, Jumei, Wang, Pei, Zhi, Qijun, Zhu, Weiwei, Shi, Xun, Kramer, Michael, Li, Di, Zhang, Lei, and Li, Guangxing
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
We report detections of scintillation arcs for pulsars in globular clusters M5, M13 and M15 for the first time using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). From observations of these arcs at multiple epochs, we infer that screen-like scattering medium exists at distances $4.1_{-0.3}^{+0.2}$ kpc, $6.7_{-0.2}^{+0.2}$ kpc and $1.3_{-1.0}^{+0.7}$ kpc from Earth in the directions of M5, M13 and M15, respectively. This means M5's and M13's scattering screens are located at $3.0_{-0.2}^{+0.1}$ kpc and $4.4_{-0.1}^{+0.1}$ kpc above the galactic plane, whereas, M15's is at $0.6_{-0.5}^{+0.3}$ kpc below the plane. We estimate the scintillation timescale and decorrelation bandwidth for each pulsar at each epoch using the one-dimensional auto-correlation in frequency and time of the dynamic spectra. We found that the boundary of the Local Bubble may have caused the scattering of M15, and detected the most distant off-plane scattering screens to date through pulsar scintillation, which provides evidence for understanding the medium circulation in the Milky Way., Comment: 9 pages, 3 figures, matches the published version
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- 2023
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18. Referral and evaluation for kidney transplantation among patients with lupus nephritis-related end-stage kidney disease.
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McPherson, Laura, Howards, Penelope, Kramer, Michael, Pastan, Stephen, Patzer, Rachel, and Plantinga, Laura
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Nephritis ,renal lupus ,systemic lupus erythematosus ,Adult ,Humans ,United States ,Kidney Transplantation ,Lupus Nephritis ,Lupus Erythematosus ,Systemic ,Kidney Failure ,Chronic ,Referral and Consultation ,Kidney - Abstract
OBJECTIVE: For the majority of patients with lupus nephritis-related end-stage kidney disease (LN-ESKD), kidney transplant is associated with better outcomes than dialysis. Access to kidney transplant requires an initial referral to a transplant center and medical evaluation prior to waitlisting. The studys objective was to examine access to these early steps in the kidney transplant process among patients with LN-ESKD. METHODS: Adults who began treatment for ESKD in the Southeast, Northeast, New York, or Ohio River Valley U.S. regions from 1/1/2012 to 12/31/2019, followed through 6/30/2021, were identified from the United States Renal Data System. Referral and evaluation start data were collected from 28 of 48 transplant centers across these regions. The exposure was primary cause of ESKD (LN-ESKD vs other-ESKD). The outcomes were referral and evaluation start at a transplant center. Cox models quantified the association between LN-ESKD (vs other-ESKD) and referral and evaluation start. RESULTS: Among 192,318 patients initiating treatment for ESKD, 0.4% had LN-ESKD. Over half (58%) of LN-ESKD patients were referred before study end, and among those referred, 66% started the evaluation. In adjusted analyses, patients with LN-ESKD were referred (HR: 1.09, 95% CI: 0.99, 1.19) and started the transplant evaluation (HR: 1.13, 95% CI: 1.00, 1.28) at a higher rate than patients with other-ESKD. Among referred patients with LN-ESKD, the median time from ESKD start to referral was 2.9 months (IQR:
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- 2024
19. The Third Fermi Large Area Telescope Catalog of Gamma-ray Pulsars
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Smith, David A., Bruel, Philippe, Clark, Colin J., Guillemot, Lucas, Kerr, Matthew T., Ray, Paul, Abdollahi, Soheila, Ajello, Marco, Baldini, Luca, Ballet, Jean, Baring, Matthew, Bassa, Cees, Gonzalez, Josefa Becerra, Bellazzini, Ronaldo, Berretta, Alessandra, Bhattacharyya, Bhaswati, Bissaldi, Elisabetta, Bonino, Raffaella, Bottacini, Eugenio, Bregeon, Johan, Burgay, Marta, Burnett, Toby, Cameron, Rob, Camilo, Fernando, Caputo, Regina, Caraveo, Patrizia, Cavazzuti, Elisabetta, Chiaro, Graziano, Ciprini, Stefano, Cognard, Ismael, Orestano, Paolo Cristarella, Crnogorcevic, Milena, Cuoco, Alessandro, Cutini, Sara, D'Ammando, Filippo, de Angelis, Alessandro, De Gaetano, Salvatore, de Menezes, Raniere, de Palma, Francesco, DeCesar, Megan, Deneva, Julia, Di Lalla, Niccola, Di Venere, Leonardo, Dirirsa, Feraol Fana, Dominguez, Alberto, Dumora, Denis, Fegan, Stephen, Ferrara, Elizabeth, Fiori, Alessio, Fleischhack, Henrike, Flynn, Chris, Franckowiak, Anna, Freire, Paulo, Fukazawa, Yasushi, Fusco, Piergiorgio, Galanti, Giorgio, Gammaldi, Viviana, Gargano, Fabio, Gasparrini, Dario, Giacchino, Federica, Giglietto, Nico, Giordano, Francesco, Giroletti, Marcello, Green, David, Grenier, Isabelle, Guiriec, Sylvain, Gustafsson, Michael, Harding, Alice, Hays, Liz, Hewitt, John, Horan, Deirdre, Hou, Xian, Jankowski, Fabian, Johnson, Tyrel, Johnson, Robert, Johnston, Simon, Kataoka, Jun, Keith, Michael J., Kramer, Michael, Kuss, Michael, Latronico, Luca, Lee, Shiu-Hang, Li, Di, Li, Jian, Limyansky, Brent, Longo, Francesco, Loparco, Francesco, Lorusso, Leonarda, Lovellette, Michael, Lower, Marcus, Lubrano, Pasquale, Lyne, Andrew, Maldera, Simone, Manchester, Richard, Manfreda, Alberto, Marelli, Martino, Marta-Devesa, Guillem, Mazziotta, Mario Nicola, McEnery, Julie, Mereu, Isabella, Michelson, Peter, Mitthumsiri, Warit, Mizuno, Tsunefumi, Moiseev, Alex, Monzani, Maria Elena, Morselli, Aldo, Negro, Michela, Nemmen, Rodrigo, Nieder, Lars, Nuss, Eric, Omodei, Nicola, Orienti, Monica, Orlando, Elena, Ormes, Jonathan F., Palatiello, Michele, Paneque, David, Panzarini, Giuliana, Persic, Massimo, Pesce-Rollins, Melissa, Pillera, Roberta, Poon, Helen, Porter, Troy, Principe, Giacomo, Raino, Silvia, Rando, Riccardo, Ransom, Scott, Razzano, Massimiliano, Razzaque, Soebur, Reimer, Anita, Reimer, Olaf, Renault-Tinacci, Nicolas, Romani, Roger, Sanchez-Conde, Miguel A., Parkinson, Pablo Saz, Scotton, Lorenzo, Serini, Davide, Sgro, Carmelo, Shannon, Ryan, Sharma, Vidushi, Siskind, Eric J., Spandre, Gloria, Spinelli, Paolo, Stappers, Ben, Stephens, Tom, Suson, Dan, Tajima, Hiro, Tak, Dongguen, Theureau, Gilles, Thompson, David, Tibolla, Omar, Torres, Diego F., Valverde, Janeth, Venter, Christo, Wadiasingh, Zorawar, Wang, Nina, Wang, Pei, Weltevrede, Patrick, Wood, Kent, and Zaharijas, Gabrijela
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
We present 294 pulsars found in GeV data from the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. Another 33 millisecond pulsars (MSPs) discovered in deep radio searches of LAT sources will likely reveal pulsations once phase-connected rotation ephemerides are achieved. A further dozen optical and/or X-ray binary systems co-located with LAT sources also likely harbor gamma-ray MSPs. This catalog thus reports roughly 340 gamma-ray pulsars and candidates, 10% of all known pulsars, compared to $\leq 11$ known before Fermi. Half of the gamma-ray pulsars are young. Of these, the half that are undetected in radio have a broader Galactic latitude distribution than the young radio-loud pulsars. The others are MSPs, with 6 undetected in radio. Overall, >235 are bright enough above 50 MeV to fit the pulse profile, the energy spectrum, or both. For the common two-peaked profiles, the gamma-ray peak closest to the magnetic pole crossing generally has a softer spectrum. The spectral energy distributions tend to narrow as the spindown power $\dot E$ decreases to its observed minimum near $10^{33}$ erg s$^{-1}$, approaching the shape for synchrotron radiation from monoenergetic electrons. We calculate gamma-ray luminosities when distances are available. Our all-sky gamma-ray sensitivity map is useful for population syntheses. The electronic catalog version provides gamma-ray pulsar ephemerides, properties and fit results to guide and be compared with modeling results., Comment: 142 pages. Accepted by the Astrophysical Journal Supplement
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- 2023
20. High-altitude Magnetospheric Emissions from Two Pulsars
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Yuan, Mao, Zhu, Weiwei, Kramer, Michael, Peng, Bo, Lu, Jiguang, Xu, Renxin, Shao, Lijing, Wang, Hong-guang, Meng, Lingqi, Niu, Jiarui, Zhao, Rushuang, Miao, Chenchen, Miao, Xueli, Xue, Mengyao, Feng, Yi, Wang, Pei, Li, Di, Zhang, Chengmin, Champion, David J., Fonseca, Emmanuel, Hu, Huanchen, Yao, Jumei, Freire, Paulo C. C., and Guo, Yanjun
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
We discover three new weak pulse components in two known pulsars, one in PSR J0304+1932 and two in PSR J1518+4904. These components are emitted about half way between the main emission beam and the interpulse beam (beam from the opposite pole). They are separated from their main pulse peak by $99^{\circ}\pm{3}^{\circ}$ for J0304+1932, $123^{\circ}.6\pm{0^{\circ}.7}$ (leading) and $93^{^{\circ}}\pm 0^{\circ}.4$ (trailing) for J1518+4904, respectively. Their peak-intensity ratios to main pulses are: $\sim$ 0.06% for J0304+1932, $\sim$ 0.17% and $\sim$ 0.83% for J1518+4904. We also analyzed flux fluctuation and profile variation of the emissions for two pulsars. The results show correlations between the weak pulses and their main pulses, indicating that these emissions come from the same pole. We estimated the emission altitude of these weak pulses and derived a height of about half of the pulsar's light-cylinder radius. These pulse components are a unique sample of high-altitude emissions from pulsars, and challenge the current pulsar emission models., Comment: 10 pages, 13 figures, Accepted for publication in ApJ
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- 2023
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21. BlackHoleCam -- Testing general relativity with pulsars orbiting Sagittarius A*
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Eatough, Ralph P., Desvignes, Gregory, Liu, Kuo, Wharton, Robert S., Noutsos, Aristedis, Torne, Pablo, Karuppusamy, Ramesh, Shao, Lijing, Kramer, Michael, Falcke, Heino, and Rezzolla, Luciano
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
BlackHoleCam is a project funded by a European Research Council Synergy Grant to build a complete astrophysical description of nearby supermassive black holes by using a combination of radio imaging, pulsar observations, stellar astrometry and general relativistic magneto-hydrodynamic models. BlackHoleCam scientists are active partners of the Event Horizon Telescope Consortium. In this talk I will discuss the use of pulsars orbiting Sagittarius A* for tests of General Relativity, the current difficulties in detecting such sources, recent results from the Galactic Centre magnetar PSR J1745-2900 and how BlackHoleCam aims to search for undiscovered pulsars in the Galactic Centre., Comment: 4 pages, 3 figures, Proceedings of The Fifteenth Marcel Grossmann Meeting on General Relativity, University of Rome La Sapienza, Italy, 1 - 7 July 2018
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- 2023
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22. Bicycle infrastructure and the incidence rate of crashes with cars: A case-control study with Strava data in Atlanta
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Garber, Michael D, Watkins, Kari E, Flanders, W Dana, Kramer, Michael R, Lobelo, RL Felipe, Mooney, Stephen J, Ederer, David J, and McCullough, Lauren E
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Transportation ,Logistics and Supply Chains ,Health Sciences ,Commerce ,Management ,Tourism and Services ,Life on Land ,Bicycle infrastructure ,Strava ,Case-control studies ,Bicycling safety ,Atlanta ,Georgia ,Causal inference ,Public Health and Health Services ,Urban and Regional Planning ,Transportation and Freight Services ,Urban and regional planning ,Transportation ,logistics and supply chains ,Public health - Abstract
Bicycling has individual and collective health benefits. Safety concerns are a deterrent to bicycling. Incomplete data on bicycling volumes has limited epidemiologic research investigating safety impacts of bicycle infrastructure, such as protected bike lanes. In this case-control study, set in Atlanta, Georgia, USA between 2016-10-01 and 2018-08-31, we estimated the incidence rate of police-reported crashes between bicyclists and motor vehicles (n = 124) on several types of infrastructure (off-street paved trails, protected bike lanes, buffered bike lanes, conventional bike lanes, and sharrows) per distance ridden and per intersection entered. To estimate underlying bicycling (the control series), we used a sample of high-resolution bicycling data from Strava, an app, combined with data from 15 on-the-ground bicycle counters to adjust for possible selection bias in the Strava data. We used model-based standardization to estimate effects of treatment on the treated. After adjustment for selection bias and confounding, estimated ratio effects on segments (excluding intersections) with protected bike lanes (incidence rate ratio [IRR] = 0.5 [95% confidence interval: 0.0, 2.5]) and buffered bike lanes (IRR = 0 [0,0]) were below 1, but were above 1 on conventional bike lanes (IRR = 2.8 [1.2, 6.0]) and near null on sharrows (IRR = 1.1 [0.2, 2.9]). Per intersection entry, estimated ratio effects were above 1 for entries originating from protected bike lanes (incidence proportion ratio [IPR] = 3.0 [0.0, 10.8]), buffered bike lanes (IPR = 16.2 [0.0, 53.1]), and conventional bike lanes (IPR = 3.2 [1.8, 6.0]), and were near 1 and below 1, respectively, for those originating from sharrows (IPR = 0.9 [0.2, 2.1]) and off-street paved trails (IPR = 0.7 [0.0, 2.9]). Protected bike lanes and buffered bike lanes had estimated protective effects on segments between intersections but estimated harmful effects at intersections. Conventional bike lanes had estimated harmful effects along segments and at intersections.
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- 2023
23. Quasi-periodic sub-pulse structure as a unifying feature for radio-emitting neutron stars
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Kramer, Michael, Liu, Kuo, Desvignes, Gregory, Karuppusamy, Ramesh, and Stappers, Ben W.
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- 2024
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24. Prognostic impact of CEBPA mutational subgroups in adult AML
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Georgi, Julia-Annabell, Stasik, Sebastian, Kramer, Michael, Meggendorfer, Manja, Röllig, Christoph, Haferlach, Torsten, Valk, Peter, Linch, David, Herold, Tobias, Duployez, Nicolas, Taube, Franziska, Middeke, Jan Moritz, Platzbecker, Uwe, Serve, Hubert, Baldus, Claudia D., Muller-Tidow, Carsten, Haferlach, Claudia, Koch, Sarah, Berdel, Wolfgang E., Woermann, Bernhard J., Krug, Utz, Braess, Jan, Hiddemann, Wolfgang, Spiekermann, Karsten, Boertjes, Emma L., Hills, Robert K., Burnett, Alan, Ehninger, Gerhard, Metzeler, Klaus, Rothenberg-Thurley, Maja, Dufour, Annika, Dombret, Hervé, Pautas, Cecile, Preudhomme, Claude, Fenwarth, Laurene, Bornhäuser, Martin, Gale, Rosemary, and Thiede, Christian
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- 2024
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25. Comparison of Polarized Radiative Transfer Codes used by the EHT Collaboration
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Prather, Ben S., Dexter, Jason, Moscibrodzka, Monika, Pu, Hung-Yi, Bronzwaer, Thomas, Davelaar, Jordy, Younsi, Ziri, Gammie, Charles F., Gold, Roman, Wong, George N., Akiyama, Kazunori, Alberdi, Antxon, Alef, Walter, Algaba, Juan Carlos, Anantua, Richard, Asada, Keiichi, Azulay, Rebecca, Bach, Uwe, Baczko, Anne-Kathrin, Ball, David, Baloković, Mislav, Barrett, John, Bauböck, Michi, Benson, Bradford A., Bintley, Dan, Blackburn, Lindy, Blundell, Raymond, Bouman, Katherine L., Bower, Geoffrey C., Boyce, Hope, Bremer, Michael, Brinkerink, Christiaan D., Brissenden, Roger, Britzen, Silke, Broderick, Avery E., Broguiere, Dominique, Bustamante, Sandra, Byun, Do-Young, Carlstrom, John E., Ceccobello, Chiara, Chael, Andrew, Chan, Chi-kwan, Chang, Dominic O., Chatterjee, Koushik, Chatterjee, Shami, Chen, Ming-Tang, Chen, Yongjun, Cheng, Xiaopeng, Cho, Ilje, Christian, Pierre, Conroy, Nicholas S., Conway, John E., Cordes, James M., Crawford, Thomas M., Crew, Geoffrey B., Cruz-Osorio, Alejandro, Cui, Yuzhu, De Laurentis, Mariafelicia, Deane, Roger, Dempsey, Jessica, Desvignes, Gregory, Dhruv, Vedant, Doeleman, Sheperd S., Dougal, Sean, Dzib, Sergio A., Eatough, Ralph P., Emami, Razieh, Falcke, Heino, Farah, Joseph, Fish, Vincent L., Fomalont, Ed, Ford, H. Alyson, Fraga-Encinas, Raquel, Freeman, William T., Friberg, Per, Fromm, Christian M., Fuentes, Antonio, Galison, Peter, García, Roberto, Gentaz, Olivier, Georgiev, Boris, Goddi, Ciriaco, Gómez-Ruiz, Arturo I., Gómez, José L., Gu, Minfeng, Gurwell, Mark, Hada, Kazuhiro, Haggard, Daryl, Haworth, Kari, Hecht, Michael H., Hesper, Ronald, Heumann, Dirk, Ho, Luis C., Ho, Paul, Honma, Mareki, Huang, Chih-Wei L., Huang, Lei, Hughes, David H., Ikeda, Shiro, Impellizzeri, C. M. Violette, Inoue, Makoto, Issaoun, Sara, James, David J., Jannuzi, Buell T., Janssen, Michael, Jeter, Britton, Jiang, Wu, Jiménez-Rosales, Alejandra, Johnson, Michael D., Jorstad, Svetlana, Joshi, Abhishek V., Jung, Taehyun, Karami, Mansour, Karuppusamy, Ramesh, Kawashima, Tomohisa, Keating, Garrett K., Kettenis, Mark, Kim, Dong-Jin, Kim, Jae-Young, Kim, Jongsoo, Kim, Junhan, Kino, Motoki, Koay, Jun Yi, Kocherlakota, Prashant, Kofuji, Yutaro, Koyama, Shoko, Kramer, Carsten, Kramer, Michael, Krichbaum, Thomas P., Kuo, Cheng-Yu, La Bella, Noemi, Lauer, Tod R., Lee, Daeyoung, Lee, Sang-Sung, Leung, Po Kin, Levis, Aviad, Li, Zhiyuan, Lico, Rocco, Lindahl, Greg, Lindqvist, Michael, Lisakov, Mikhail, Liu, Jun, Liu, Kuo, Liuzzo, Elisabetta, Lo, Wen-Ping, Lobanov, Andrei P., Loinard, Laurent, Lonsdale, Colin J., Lu, Ru-Sen, MacDonald, Nicholas R., Mao, Jirong, Marchili, Nicola, Markoff, Sera, Marrone, Daniel P., Marscher, Alan P., Martí-Vidal, Iván, Matsushita, Satoki, Matthews, Lynn D., Medeiros, Lia, Menten, Karl M., Michalik, Daniel, Mizuno, Izumi, Mizuno, Yosuke, Moran, James M., Moriyama, Kotaro, Müller, Cornelia, Mus, Alejandro, Musoke, Gibwa, Myserlis, Ioannis, Nadolski, Andrew, Nagai, Hiroshi, Nagar, Neil M., Nakamura, Masanori, Narayan, Ramesh, Narayanan, Gopal, Natarajan, Iniyan, Nathanail, Antonios, Fuentes, Santiago Navarro, Neilsen, Joey, Neri, Roberto, Ni, Chunchong, Noutsos, Aristeidis, Nowak, Michael A., Oh, Junghwan, Okino, Hiroki, Olivares, Héctor, Ortiz-León, Gisela N., Oyama, Tomoaki, Özel, Feryal, Palumbo, Daniel C. M., Paraschos, Georgios Filippos, Park, Jongho, Parsons, Harriet, Patel, Nimesh, Pen, Ue-Li, Pesce, Dominic W., Piétu, Vincent, Plambeck, Richard, PopStefanija, Aleksandar, Porth, Oliver, Pötzl, Felix M., Preciado-López, Jorge A., Psaltis, Dimitrios, Ramakrishnan, Venkatessh, Rao, Ramprasad, Rawlings, Mark G., Raymond, Alexander W., Rezzolla, Luciano, Ricarte, Angelo, Ripperda, Bart, Roelofs, Freek, Rogers, Alan, Ros, Eduardo, Romero-Cañizales, Cristina, Roshanineshat, Arash, Rottmann, Helge, Roy, Alan L., Ruiz, Ignacio, Ruszczyk, Chet, Rygl, Kazi L. J., Sánchez, Salvador, Sánchez-Argüelles, David, Sánchez-Portal, Miguel, Sasada, Mahito, Satapathy, Kaushik, Savolainen, Tuomas, Schloerb, F. Peter, Schonfeld, Jonathan, Schuster, Karl-Friedrich, Shao, Lijing, Shen, Zhiqiang, Small, Des, Sohn, Bong Won, SooHoo, Jason, Souccar, Kamal, Sun, He, Tazaki, Fumie, Tetarenko, Alexandra J., Tiede, Paul, Tilanus, Remo P. J., Titus, Michael, Torne, Pablo, Traianou, Efthalia, Trent, Tyler, Trippe, Sascha, Turk, Matthew, van Bemmel, Ilse, van Langevelde, Huib Jan, van Rossum, Daniel R., Vos, Jesse, Wagner, Jan, Ward-Thompson, Derek, Wardle, John, Weintroub, Jonathan, Wex, Norbert, Wharton, Robert, Wielgus, Maciek, Wiik, Kaj, Witzel, Gunther, Wondrak, Michael F., Wu, Qingwen, Yamaguchi, Paul, Yfantis, Aristomenis, Yoon, Doosoo, Young, André, Young, Ken, Yu, Wei, Yuan, Feng, Yuan, Ye-Fei, Zensus, J. Anton, Zhang, Shuo, Zhao, Guang-Yao, and Zhao, Shan-Shan
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
Interpretation of resolved polarized images of black holes by the Event Horizon Telescope (EHT) requires predictions of the polarized emission observable by an Earth-based instrument for a particular model of the black hole accretion system. Such predictions are generated by general relativistic radiative transfer (GRRT) codes, which integrate the equations of polarized radiative transfer in curved spacetime. A selection of ray-tracing GRRT codes used within the EHT collaboration is evaluated for accuracy and consistency in producing a selection of test images, demonstrating that the various methods and implementations of radiative transfer calculations are highly consistent. When imaging an analytic accretion model, we find that all codes produce images similar within a pixel-wise normalized mean squared error (NMSE) of 0.012 in the worst case. When imaging a snapshot from a cell-based magnetohydrodynamic simulation, we find all test images to be similar within NMSEs of 0.02, 0.04, 0.04, and 0.12 in Stokes I, Q, U , and V respectively. We additionally find the values of several image metrics relevant to published EHT results to be in agreement to much better precision than measurement uncertainties., Comment: Accepted for publication in ApJ
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- 2023
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26. FRB 20210405I: a nearby Fast Radio Burst localised to sub-arcsecond precision with MeerKAT
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Driessen, Laura Nicole, Barr, Ewan, Buckley, David, Caleb, Manisha, Chen, Hao, Chen, Weiwei, Gromadzki, Mariusz, Jankowski, Fabian, Kraan-Korteweg, Renee, Kramer, Michael, Palmerio, Jesse, Rajwade, Kaustubh, Stappers, Ben, Tremou, Evangelia, Vergani, Susanna, Woudt, Patrick, Bezuidenhout, Mechiel Christiaan, Malenta, Mateusz, Morello, Vincent, Sanidas, Sotiris, Surnis, Mayuresh, and Fender, Rob
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
We present the first sub-arcsecond localised Fast Radio Burst (FRB) detected using MeerKAT. FRB 20210405I was detected in the incoherent beam using the MeerTRAP pipeline on 2021 April 05 with a signal to noise ratio of 140.8 and a dispersion measure of 565.17 pc cm$^{-3}$. It was detected while MeerTRAP was observing commensally with the ThunderKAT large survey project, and was sufficiently bright that we could use the ThunderKAT 8s images to localise the FRB. Two different models of the dispersion measure in the Milky Way and halo suggest that the source is either right at the edge of the Galaxy, or outside. This highlights the uncertainty in the Milky Way dispersion measure models, particularly in the Galactic Plane, and the uncertainty of Milky Way halo models. Further investigation and modelling of these uncertainties will be facilitated by future detections and localisations of nearby FRBs. We use the combined localisation, dispersion measure, scattering, specific luminosity and chance coincidence probability information to find that the origin is most likely extra-galactic and identify the likely host galaxy of the FRB: 2MASS J1701249$-$4932475. Using SALT spectroscopy and archival observations of the field, we find that the host is a disk/spiral galaxy at a redshift of $z=0.066$., Comment: 15 pages, 4 tables, 10 figures. Accepted to MNRAS
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- 2023
27. Pulsar Scintillation Studies with LOFAR: II. Dual-frequency scattering study of PSR J0826+2637 with LOFAR and NenuFAR
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Wu, Ziwei, Coles, William A., Verbiest, Joris P. W., Ambalappat, Krishnakumar Moochickal, Tiburzi, Caterina, Grießmeier, Jean-Mathias, Main, Robert A., Liu, Yulan, Kramer, Michael, Wucknitz, Olaf, Porayko, Nataliya, Osłowski, Stefan, Nielsen, Ann-Sofie Bak, Donner, Julian Y., Hoeft, Matthias, Brüggen, Marcus, Vocks, Christian, Dettmar, Ralf-Jürgen, Theureau, Gilles, Serylak, Maciej, Kondratiev, Vladislav, McKee, James W., Shaifullah, Golam M., Kravtsov, Ihor P., Zakharenko, Vyacheslav V., Ulyanov, Oleg, Konovalenko, Olexandr O., Zarka, Philippe, Cecconi, Baptiste, Koopmans, Léon V. E., and Corbel, Stéphane
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
Interstellar scattering (ISS) of radio pulsar emission can be used as a probe of the ionised interstellar medium (IISM) and causes corruptions in pulsar timing experiments. Two types of ISS phenomena (intensity scintillation and pulse broadening) are caused by electron density fluctuations on small scales (< 0.01 AU). Theory predicts that these are related, and both have been widely employed to study the properties of the IISM. Larger scales ($\sim$1-100\,AU) cause measurable changes in dispersion and these can be correlated with ISS observations to estimate the fluctuation spectrum over a very wide scale range. IISM measurements can often be modeled by a homogeneous power-law spatial spectrum of electron density with the Kolmogorov ($-11/3$) spectral exponent. Here we aim to test the validity of using the Kolmogorov exponent with PSR~J0826+2637. We do so using observations of intensity scintillation, pulse broadening and dispersion variations across a wide fractional bandwidth (20 -- 180\,MHz). We present that the frequency dependence of the intensity scintillation in the high frequency band matches the expectations of a Kolmogorov spectral exponent but the pulse broadening in the low frequency band does not change as rapidly as predicted with this assumption. We show that this behavior is due to an inhomogeneity in the scattering region, specifically that the scattering is dominated by a region of transverse size $\sim$40\,AU. The power spectrum of the electron density, however, maintains the Kolmogorov spectral exponent from spatial scales of 5$\times10^{-6}$\,AU to $\sim$100\,AU., Comment: Accepted for publication in MNRAS, typo fixed
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- 2023
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28. Missing for 20 years: MeerKAT re-detects the elusive binary pulsar M30B
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Balakrishnan, Vishnu, Freire, Paulo, Ransom, Scott, Ridolfi, Alessandro, Barr, Ewan, Chen, Weiwei, Krishnan, Vivek Venkatraman, Champion, David J., Kramer, Michael, Gautam, Tasha, Padmanabh, Prajwal, Men, Yunpeng, Abbate, Federico, Stappers, Benjamin, Stairs, Ingrid, Keane, Evan, and Possenti, Andrea
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
PSR J2140$-$2311B is a 13-ms pulsar discovered in 2001 in a 7.8-hour Green Bank Telescope (GBT) observation of the core-collapsed globular cluster M30 and predicted to be in a highly eccentric binary orbit. This pulsar has eluded detection since then, therefore its precise orbital parameters have remained a mystery until now. In this work, we present the confirmation of this pulsar using observations taken with the UHF receivers of the MeerKAT telescope as part of the TRAPUM Large Survey Project. Taking advantage of the beamforming capability of our backends, we have localized it, placing it $1.2(1)^\prime$ from the cluster centre. Our observations have enabled the determination of its orbit: it is highly eccentric ($e = 0.879$) with an orbital period of $6.2$ days. We also measured the rate of periastron advance, $\dot{\omega} = 0.078 \pm 0.002\, \rm deg \, yr^{-1}$. Assuming that this effect is fully relativistic, general relativity provides an estimate of the total mass of the system, $M_{\rm TOT} = 2.53 \pm 0.08$ M$_{\odot}$, consistent with the lightest double neutron star systems known. Combining this with the mass function of the system gives the pulsar and companion masses of $m_p < 1.43 \, \rm M_{\odot}$ and $m_c > 1.10 \, \rm M_{\odot}$ respectively. The massive, undetected companion could either be a massive WD or a NS. M30B likely formed as a result of a secondary exchange encounter. Future timing observations will allow the determination of a phase-coherent timing solution, vastly improving our uncertainty in $\dot{\omega}$ and likely enabling the detection of additional relativistic effects which will determine $m_p$ and $m_c$., Comment: Accepted for publication in the Astrophysical Journal Letters (ApJL)
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- 2023
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29. Christlich-Islamischer Religionsunterricht im Teamteaching – einleitendes Vorwort
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Gmoser, Agnes, primary, Kramer, Michael, additional, and Weirer, Wolfgang, additional
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- 2024
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30. Lokale Theorien als Aspekte einer Didaktik religionskooperativer Lehr-/Lernprozesse im Kontext der Fachdidaktischen Entwicklungsforschung
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Gmoser, Agnes, primary, Kramer, Michael, additional, Mešanović, Mevlida, additional, Weirer, Wolfgang, additional, Wenig, Eva, additional, and Yağdı, Şenol, additional
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- 2024
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31. Sechs Jahre Forschungsarbeit im interreligiösen Projektteam – eine Reflexion
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Gmoser, Agnes, primary, Kramer, Michael, additional, Mešanović, Mevlida, additional, Weirer, Wolfgang, additional, Wenig, Eva, additional, and Yağdi, Şenol, additional
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- 2024
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32. The MeerKAT Pulsar Timing Array: First Data Release
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Miles, Matthew T., Shannon, Ryan M., Bailes, Matthew, Reardon, Daniel J., Keith, Michael J., Cameron, Andrew D., Parthasarathy, Aditya, Shamohammadi, Mohsen, Spiewak, Renee, van Straten, Willem, Buchner, Sarah, Camilo, Fernando, Geyer, Marisa, Karastergiou, Aris, Kramer, Michael, Serylak, Maciej, Theureau, Gilles, and Krishnan, Vivek Venkatraman
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
We present the first 2.5 years of data from the MeerKAT Pulsar Timing Array (MPTA), part of MeerTime, a MeerKAT Large Survey Project. The MPTA aims to precisely measure pulse arrival times from an ensemble of 88 pulsars visible from the Southern Hemisphere, with the goal of contributing to the search, detection and study of nanohertz-frequency gravitational waves as part of the International Pulsar Timing Array. This project makes use of the MeerKAT telescope, and operates with a typical observing cadence of two weeks using the L-band receiver that records data from 856-1712 MHz. We provide a comprehensive description of the observing system, software, and pipelines used and developed for the MeerTime project. The data products made available as part of this data release are from the 78 pulsars that had at least $30$ observations between the start of the MeerTime programme in February 2019 and October 2021. These include both sub-banded and band-averaged arrival times, as well as the initial timing ephemerides, noise models, and the frequency-dependent standard templates (portraits) used to derive pulse arrival times. After accounting for detected noise processes in the data, the frequency-averaged residuals of $67$ of the pulsars achieved a root-mean-square residual precision of $< 1 \mu \rm{s}$. We also present a novel recovery of the clock correction waveform solely from pulsar timing residuals, and an exploration into preliminary findings of interest to the international pulsar timing community. The arrival times, standards and full Stokes parameter calibrated pulsar timing archives are publicly available., Comment: 18 pages, 6 figures
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- 2022
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33. Searches for Shapiro delay in seven binary pulsars using the MeerKAT telescope
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Shamohammadi, Mohsen, Bailes, Matthew, Freire, Paulo C. C., Parthasarathy, Aditya, Reardon, Daniel J., Shannon, Ryan M., Krishnan, Vivek Venkatraman, Bernadich, Miquel C. i., Cameron, Andrew D., Champion, David J., Corongiu, Alessandro, Flynn, Christopher, Geyer, Marisa, Kramer, Michael, Miles, Matthew T., Possenti, Andrea, and Spiewak, Renee
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
Precision timing of millisecond pulsars in binary systems enables observers to detect the relativistic Shapiro delay induced by space time curvature. When favourably aligned, this enables constraints to be placed on the component masses and system orientation. Here we present the results of timing campaigns on seven binary millisecond pulsars observed with the 64-antenna MeerKAT radio telescope that show evidence of Shapiro delay: PSRs~J0101$-$6422, J1101$-$6424, J1125$-$6014, J1514$-$4946, J1614$-$2230, J1732$-$5049, and J1909$-$3744. Evidence for Shapiro delay was found in all of the systems, and for three the orientations and data quality enabled strong constraints on their orbital inclinations and component masses. For PSRs~J1125$-$6014, J1614$-$2230 and J1909$-$3744, we determined pulsar masses to be $M_{\rm p} = 1.68\pm 0.17 \, {\rm M_{\odot}} $, $1.94\pm 0.03 \, {\rm M_{\odot}} $ and $1.45 \pm 0.03 \, {\rm M_{\odot}}$, and companion masses to be $M_{\rm c} = 0.33\pm 0.02 \, {\rm M_{\odot}} $, $0.495\pm 0.005 \, {\rm M_{\odot}} $ and $0.205 \pm 0.003 \, {\rm M_{\odot}}$, respectively. This provides the first independent confirmation of PSR~J1614$-$2230's mass, one of the highest known. The Shapiro delays measured for PSRs~J0101$-$6422, J1101$-$6424, J1514$-$4946, and J1732$-$5049 were only weak, and could not provide interesting component mass limits. Despite a large number of millisecond pulsars being routinely timed, relatively few have accurate masses via Shapiro delays. We use simulations to show that this is expected, and provide a formula for observers to assess how accurately a pulsar mass can be determined. We also discuss the observed correlation between pulsar companion masses and spin period, and the anti-correlation between recycled pulsar mass and their companion masses., Comment: 19 pages, 8 figures
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- 2022
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34. The Thousand-Pulsar-Array programme on MeerKAT XI: Application of the rotating vector model
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Johnston, Simon, Kramer, Michael, Karastergiou, Aris, Keith, Mike, Oswald, Lucy, Parthasarathy, Aditya, and Weltevrede, Patrick
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
In spite of the rich phenomenology of the polarization properties of radio pulsars, the rotating vector model (RVM) created 50 years ago remains the best method to determine the beam geometry of a pulsar. We apply the RVM to a sample of 854 radio pulsars observed with the MeerKAT telescope in order to draw conclusions about the population of pulsars as a whole. The main results are that (i) the geometrical interpretation of the position angle traverse is valid in the majority of the population, (ii) the pulsars for which the RVM fails tend to have a high fraction of circular polarization compared to linear polarization, (iii) emission heights obtained through both geometrical and relativistic methods show that the majority of pulsars must have emission heights less than 1000~km independent of spin period, (iv) orthogonal mode jumps are seen in the position angle traverse in about one third of the population. All these results are weakly dependent on the pulsar spin-down energy., Comment: accepted by MNRAS
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- 2022
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35. Precession of magnetars: dynamical evolutions and modulations on polarized electromagnetic waves
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Gao, Yong, Shao, Lijing, Desvignes, Gregory, Jones, David Ian, Kramer, Michael, and Yim, Garvin
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
Magnetars are conjectured to be highly magnetized neutron stars (NSs). Strong internal magnetic field and elasticity in the crust may deform the stars and lead to free precession. We study the precession dynamics of triaxially-deformed NSs incorporating the near-field and the far-field electromagnetic torques. We obtain timing residuals for different NS geometries and torques. We also investigate the polarized X-ray and radio signals from precessing magnetars. The modulations on the Stokes parameters are obtained for thermal X-rays emitted from the surface of magnetars. For radio signals, we apply the simple rotating vector model (RVM) to give the modulations on the position angle (PA) of the polarization. Our results are comprehensive, ready to be used to search for magnetar precession with timing data and polarizations of X-ray and radio emissions. Future observations of precessing magnetars will give us valuable information on the geometry and the strength of the strong magnetic fields, the emission geometry, as well as the equation of state (EoS) of NSs., Comment: 18 pages, 18 figures; accepted by MNRAS
- Published
- 2022
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36. Towards a Taxonomy of Multi-Agent Simulation Models to Determine Disruptive Technology Adoption Behaviour in the Wine Industry
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Kramer, Michael Paul, Viana, Joe, Mueller, Rolf A. E., Hanf, Claus-Hennig, Hanf, Jon H., Thrassou, Alkis, Series Editor, Vrontis, Demetris, Series Editor, Galati, Antonino, editor, and Fiore, Mariantonietta, editor
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- 2024
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37. Ausgewählte rechtssoziologische Erkenntnisse zu vorherrschenden Herausforderungen mit 'dem Islam' und dem islamischen Religionsunterricht der IGGÖ an Mittelschulen
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Kramer, Michael, Aslan, Ednan, Series Editor, and Nili-Freudenschuß, Tamara, editor
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- 2024
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38. Sciences with Thai National Radio Telescope
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Jaroenjittichai, Phrudth, Sugiyama, Koichiro, Kramer, Busaba H., Soonthornthum, Boonrucksar, Akahori, Takuya, Asanok, Kitiyanee, Baan, Willem, Bran, Sherin Hassan, Breen, Shari L., Cho, Se-Hyung, Chanapote, Thanapol, Dodson, Richard, Ellingsen, Simon P., Etoka, Sandra, Gray, Malcolm D., Green, James A., Hada, Kazuhiro, Halson, Marcus, Hirota, Tomoya, Honma, Mareki, Imai, Hiroshi, Johnston, Simon, Kim, Kee-Tae, Kramer, Michael, Li, Di, Macatangay, Ronald, Menten, Karl M., Minh, Young Chol, Mkrtichian, David, Pimpanuwat, Bannawit, Richards, Anita M. S., Rioja, Maria, Rujopakarn, Wiphu, Sakai, Daisuke, Sakai, Nobuyuki, Samanso, Nattida, Sanpa-arsa, Siraprapa, Semenko, Eugene, Sunada, Kazuyoshi, Surapipith, Vanisa, Thoonsaengngam, Nattaporn, Voronkov, Maxim A., Wongphecauxson, Jompoj, Yadav, Ram Kesh, Zhang, Bo, Zheng, Xing Wu, and Poshyachinda, Saran
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Astrophysics - Instrumentation and Methods for Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
This White Paper summarises potential key science topics to be achieved with Thai National Radio Telescope (TNRT). The commissioning phase has started in mid 2022. The key science topics consist of "Pulsars and Fast Radio Bursts (FRBs)", "Star Forming Regions (SFRs)", "Galaxy and Active Galactic Nuclei (AGNs)", "Evolved Stars", "Radio Emission of Chemically Peculiar (CP) Stars", and "Geodesy", covering a wide range of observing frequencies in L/C/X/Ku/K/Q/W-bands (1-115 GHz). As a single-dish instrument, TNRT is a perfect tool to explore time domain astronomy with its agile observing systems and flexible operation. Due to its ideal geographical location, TNRT will significantly enhance Very Long Baseline Interferometry (VLBI) arrays, such as East Asian VLBI Network (EAVN), Australia Long Baseline Array (LBA), European VLBI Network (EVN), in particular via providing a unique coverage of the sky resulting in a better complete "uv" coverage, improving synthesized-beam and imaging quality with reducing side-lobes. This document highlights key science topics achievable with TNRT in single-dish mode and in collaboration with VLBI arrays., Comment: 75 pages, 16 figures, 15 tables. White Paper for Potential Key Sciences to be Achieved with Thai National Radio Telescope (TNRT)
- Published
- 2022
39. Interstellar scintillation and polarization of PSR B0656+14 in the Monogem Ring
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Yao, Jumei, Coles, William A., Manchester, Richard N., Stinebring, Daniel R., Kramer, Michael, Wang, Na, Li, Di, Zhu, Weiwei, Feng, Yi, Yuan, Jianping, and Wang, Pei
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Astrophysics of Galaxies - Abstract
High sensitivity interstellar scintillation and polarization observations of PSR~B0656+14 made at three epochs over a year using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) show that the scattering is dominated by two different compact regions. We identify the one nearer to the pulsar with the shell of the Monogem Ring, thereby confirming the association. The other is probably associated with the Local Bubble. We find that the observed position angles of the pulsar spin axis and the space velocity are significantly different, with a separation of $19\fdg3\pm$0\fdg8, inconsistent with a previously published near-perfect alignment of $1\degr\pm 2\degr$. The two independent scattering regions are clearly defined in the secondary spectra which show two strong forward parabolic arcs. The arc curvatures imply that the scattering screens corresponding to the outer and inner arcs are located approximately 28~pc from PSR B0656+14 and 185~pc from the Earth, respectively. Comparison of the observed Doppler profiles with electromagnetic simulations shows that both scattering regions are mildly anisotropic. For the outer arc, we estimate the anisotropy $A_R$ to be approximately 1.3, with the scattering irregularities aligned parallel to the pulsar velocity. For the outer arc, we compare the observed delay profiles with delay profiles computed from a theoretical strong-scattering model. Our results suggest that the spatial spectrum of the scattering irregularities in the Monogem Ring is flatter than Kolmogorov, but further observations are required to confirm this., Comment: 21 pages, 11 figures, accepted for publication in the Astronomical Journal
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- 2022
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40. The SPAN512 mid-latitude pulsar survey at the Nan\c{c}ay Radio Telescope
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Desvignes, Gregory, Cognard, Ismael, Smith, David A., Champion, David, Guillemot, Lucas, Kramer, Michael, Lespagnol, Patrice, Octau, Franck, and Theureau, Gilles
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
The large number of ongoing surveys for pulsars and transients at various radio observatories is motivated by the science obtained from these sources. Timing and polarisation analysis of relativistic binaries can place strong constraints on theories of gravity. The observation of a growing number of millisecond pulsars (MSPs) spread over the celestial sphere may allow the detection of a stochastic gravitational wave background arising from supermassive black hole binaries. A more complete sample of young pulsars improves our knowledge of neutron star birth and evolution. Transients such as fast radio bursts can serve to probe the intergalactic medium. The SPAN512 pulsar survey covers intermediate Galactic latitudes using the L-band receiver of the Nan\c{c}ay Radio Telescope (NRT). The survey covers 224 sq. deg. of the sky for a total exposure time of 2200 h. Population syntheses predict the discovery of 3 to 19 new normal pulsars and a few MSPs. We present detailed modelling of the NRT beam with its L-band receiver and its sensitivity which we used to precisely assess the expected survey yield. We used the flexible Pulsar Arecibo L-band Feed Array data processing pipeline to search the 47 TB of SPAN512 data for pulsars and transients. The SPAN512 survey discovered two new MSPs and one new middle-aged pulsar. We focus on the analysis of the 2.4-ms spin period pulsar J2205+6012 for which we also report the detection of gamma-ray pulsations. Its narrow pulse width (35 $\mu$s at an observing frequency of 2.55 GHz) allows for sub-microsecond timing precision over 8 years, with exciting prospects for pulsar timing array programs., Comment: 13 pages, 11 figures, 5 tables. Accepted in A&A
- Published
- 2022
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41. Unlikely Collaboration: Gertrude Stein, Bernard Faÿ, and the Vichy Dilemma by Barbara Will (review)
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Kramer, Michael P.
- Published
- 2015
42. Using a Geolocation Social Networking Application to Calculate the Population Density of Sex-Seeking Gay Men for Research and Prevention Services
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Delaney, Kevin P, Kramer, Michael R, Waller, Lance A, Flanders, W Dana, and Sullivan, Patrick S
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Computer applications to medicine. Medical informatics ,R858-859.7 ,Public aspects of medicine ,RA1-1270 - Abstract
BackgroundIn the United States, human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) continues to have a heavy impact on men who have sex with men (MSM). Among MSM, black men under the age of 30 are at the most risk for being diagnosed with HIV. The US National HIV/AIDS strategy recommends intensifying efforts in communities that are most heavily impacted; to do so requires new methods for identifying and targeting prevention resources to young MSM, especially young MSM of color. ObjectiveWe piloted a methodology for using the geolocation features of social and sexual networking applications as a novel approach to calculating the local population density of sex-seeking MSM and to use self-reported age and race from profile postings to highlight areas with a high density of minority and young minority MSM in Atlanta, Georgia. MethodsWe collected data from a geographically systematic sample of points in Atlanta. We used a sexual network mobile phone app and collected application profile data, including age, race, and distance from each point, for either the 50 closest users or for all users within a 2-mile radius of sampled points. From these data, we developed estimates of the spatial density of application users in the entire city, stratified by race. We then compared the ratios and differences between the spatial densities of black and white users and developed an indicator of areas with the highest density of users of each race. ResultsWe collected data from 2666 profiles at 79 sampled points covering 883 square miles; overlapping circles of data included the entire 132.4 square miles in Atlanta. Of the 2666 men whose profiles were observed, 1563 (58.63%) were white, 810 (30.38%) were black, 146 (5.48%) were another race, and 147 (5.51%) did not report a race in their profile. The mean age was 31.5 years, with 591 (22.17%) between the ages of 18-25, and 496 (18.60%) between the ages of 26-30. The mean spatial density of observed profiles was 33 per square mile, but the distribution of profiles observed across the 79 sampled points was highly skewed (median 17, range 1-208). Ratio, difference, and distribution outlier measures all provided similar information, highlighting areas with higher densities of minority and young minority MSM. ConclusionsUsing a limited number of sampled points, we developed a geospatial density map of MSM using a social-networking sex-seeking app. This approach provides a simple method to describe the density of specific MSM subpopulations (users of a particular app) for future HIV behavioral surveillance and allow targeting of prevention resources such as HIV testing to populations and areas of highest need.
- Published
- 2014
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43. Radio detection of an elusive millisecond pulsar in the Globular Cluster NGC 6397
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Zhang, Lei, Ridolfi, Alessandro, Blumer, Harsha, Freire, Paulo, Manchester, Richard N., McLaughlin, Maura, Kremer, Kyle, Cameron, Andrew D., Zhang, Zhiyu, Behrend, Jan, Burgay, Marta, Buchner, Sarah, Champion, David J., Chen, Weiwei, Dai, Shi, Feng, Yi, Fu, Xiaoting, Guo, Meng, Hobbs, George, Keane, Evan F., Kramer, Michael, Levin, Lina, Li, Xiangdong, Ni, Mengmeng, Pan, Jingshan, Padmanabh, Prajwal V., Possenti, Andrea, Ransom, Scott M., Tsai, Chao-Wei, Krishnan, Vivek Venkatraman, Wang, Pei, Zhang, Jie, Zhi, Qijun, Zhang, Yongkun, and Li, Di
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
We report the discovery of a new 5.78 ms-period millisecond pulsar (MSP), PSR J1740-5340B (NGC 6397B), in an eclipsing binary system discovered with the Parkes radio telescope (now also known as Murriyang), Australia, and confirmed with the MeerKAT radio telescope in South Africa. The measured orbital period, 1.97 days, is the longest among all eclipsing binaries in globular clusters (GCs) and consistent with that of the coincident X-ray source U18, previously suggested to be a 'hidden MSP'. Our XMM-Newton observations during NGC 6397B's radio quiescent epochs detected no X-ray flares. NGC 6397B is either a transitional MSP or an eclipsing binary in its initial stage of mass transfer after the companion star left the main sequence. The discovery of NGC 6397B potentially reveals a subgroup of extremely faint and heavily obscured binary pulsars, thus providing a plausible explanation to the apparent dearth of binary neutron stars in core-collapsed GCs as well as a critical constraint on the evolution of GCs.
- Published
- 2022
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44. Discovery of a radio emitting neutron star with an ultra-long spin period of 76 seconds
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Caleb, Manisha, Heywood, Ian, Rajwade, Kaustubh, Malenta, Mateusz, Stappers, Benjamin, Barr, Ewan, Chen, Weiwei, Morello, Vincent, Sanidas, Sotiris, Eijnden, Jakob van den, Kramer, Michael, Buckley, David, Brink, Jaco, Motta, Sara Elisa, Woudt, Patrick, Weltevrede, Patrick, Jankowski, Fabian, Surnis, Mayuresh, Buchner, Sarah, Bezuidenhout, Mechiel Christiaan, Driessen, Laura Nicole, and Fender, Rob
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
The radio-emitting neutron star population encompasses objects with spin periods ranging from milliseconds to tens of seconds. As they age and spin more slowly, their radio emission is expected to cease. We present the discovery of an ultra-long period radio-emitting neutron star, J0901-4046, with spin properties distinct from the known spin and magnetic-decay powered neutron stars. With a spin-period of 75.88 s, a characteristic age of 5.3 Myr, and a narrow pulse duty-cycle, it is uncertain how radio emission is generated and challenges our current understanding of how these systems evolve. The radio emission has unique spectro-temporal properties such as quasi-periodicity and partial nulling that provide important clues to the emission mechanism. Detecting similar sources is observationally challenging, which implies a larger undetected population. Our discovery establishes the existence of ultra-long period neutron stars, suggesting a possible connection to the evolution of highly magnetized neutron stars, ultra-long period magnetars, and fast radio bursts, Comment: Published in Nature Astronomy - https://www.nature.com/articles/s41550-022-01688-x
- Published
- 2022
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45. Towards multiple ion applications in particle therapy
- Author
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Inaniwa, Taku, primary, Kramer, Michael, additional, Mairani, Andrea, additional, Scifoni, Emanuele, additional, and Sokol, Olga, additional
- Published
- 2023
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46. The science case and challenges of space-borne sub-millimeter interferometry
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Gurvits, Leonid I., Paragi, Zsolt, Amils, Ricardo I., van Bemmel, Ilse, Boven, Paul, Casasola, Viviana, Conway, John, Davelaar, Jordy, Díez-González, M. Carmen, Falcke, Heino, Fender, Rob, Frey, Sándor, Fromm, Christian M., Gallego-Puyol, Juan D., García-Miró, Cristina, Garrett, Michael A., Giroletti, Marcello, Goddi, Ciriaco, Gómez, José L., van der Gucht, Jeffrey, Guirado, José Carlos, Haiman, Zoltán, Helmich, Frank, Hudson, Ben, Humphreys, Elizabeth, Impellizzeri, Violette, Janssen, Michael, Johnson, Michael D., Kovalev, Yuri Y., Kramer, Michael, Lindqvist, Michael, Linz, Hendrik, Liuzzo, Elisabetta, Lobanov, Andrei P., López-Fernández, Isaac, Malo-Gómez, Inmaculada, Masania, Kunal, Mizuno, Yosuke, Plavin, Alexander V., Rajan, Raj T., Rezzolla, Luciano, Roelofs, Freek, Ros, Eduardo, Rygl, Kazi L. J., Savolainen, Tuomas, Schuster, Karl, Venturi, Tiziana, Verkouter, Marjolein, de Vicente, Pablo, Visser, Pieter N. A. M., Wiedner, Martina C., Wielgus, Maciek, Wiik, Kaj, and Zensus, J. Anton
- Subjects
Astrophysics - Instrumentation and Methods for Astrophysics ,Astrophysics - Cosmology and Nongalactic Astrophysics ,Astrophysics - Astrophysics of Galaxies - Abstract
Ultra-high angular resolution in astronomy has always been an important vehicle for making fundamental discoveries. Recent results in direct imaging of the vicinity of the supermassive black hole in the nucleus of the radio galaxy M87 by the millimeter VLBI system Event Horizon Telescope and various pioneering results of the Space VLBI mission RadioAstron provided new momentum in high angular resolution astrophysics. In both mentioned cases, the angular resolution reached the values of about 10-20 microrcseconds. Further developments toward at least an order of magnitude "sharper" values are dictated by the needs of astrophysical studies and can only be achieved by placing millimeter and submillimeter wavelength interferometric systems in space. A concept of such the system, called Terahertz Exploration and Zooming-in for Astrophysics (THEZA), has been proposed in the framework of the ESA Call for White Papers for the Voayage 2050 long term plan in 2019. In the current paper we discuss several approaches for addressing technological challenges of the THEZA concept. In particular, we consider a novel configuration of a space-borne millimeter/sub-millimeter antenna which might resolve several bottlenecks in creating large precise mechanical structures. The paper also presents an overview of prospective space-qualified technologies of low-noise analogue front-end instrumentation for millimeter/sub-millimeter telescopes, data handling and processing. The paper briefly discusses approaches to the interferometric baseline state vector determination and synchronisation and heterodyning system. In combination with the original ESA Voyage 2050 White Paper, the current work sharpens the case for the next generation microarcsceond-level imaging instruments and provides starting points for further in-depth technology trade-off studies., Comment: The paper on 29 pages contains 12 figures, accepted for publication in Acta Astronautica, based on the presentation at the 72nd IAC, Dubai, UAE, October 2021
- Published
- 2022
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47. Long-term scintillation studies of EPTA pulsars. I. Observations and basic results
- Author
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Liu, Yulan, Verbiest, Joris P. W., Main, Robert A., Wu, Ziwei, Ambalappat, Krishnakumar Moochickal, Champion, David J., Cognard, Ismaël, Guillemot, Lucas, Gaikwad, Madhuri, Janssen, Gemma H., Kramer, Michael, Keith, Michael J., Karuppusamy, Ramesh, Künkel, Lars, Liu, Kuo, McKee, James W., Mickaliger, Mitchell B., Stappers, Ben W., Shaifullah, Golam. M., and Theureau, Gilles
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
Interstellar scintillation analysis of pulsars allows us to probe the small-scale distribution and inhomogeneities of the ionized interstellar medium. Our priority is to present the data set and the basic measurements of scintillation parameters of pulsars employing long-term scintillation observations carried out from 2011 January to 2020 August by the European Pulsar Timing Array radio telescopes in the 21-cm and 11-cm bands. Additionally, we aim to identify future possible lines of study using this long-term scintillation dataset. We present the long-term time series of $\nu_{\rm d}$ and $\tau_{\rm d}$ for 13 pulsars. Sanity-checks and comparisons indicate that the scintillation parameters of our work and previously published works are mostly consistent. For two pulsars, PSRs~J1857+0943 and J1939+2134, we were able to obtain measurements of the $\nu_{\rm d}$ at both bands, which allows us to derive the time series of frequency scaling indices with a mean and a standard deviation of 2.82$\pm$1.95 and 3.18$\pm$0.60, respectively. We found some interesting features which will be studied in more detail in subsequent papers in this series: (i) in the time series of PSR~J1939+2134, where the scintillation bandwidth sharply increases or decreases associated with a sharp change of dispersion measure; (ii) PSR~J0613$-$0200 and PSR~J0636+5126 show a strong annual variation in the time series of the $\tau_{\rm d}$; (iii) PSR~J1939+2134 shows a weak anti-correlation between scintillation timescale and dispersion in WSRT data., Comment: 18 pages, 6 figures, 4 tables, accepted for publication in A&A
- Published
- 2022
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48. “So that I can trust them with my body:” How people with low incomes who may become pregnant define and prioritize quality reproductive health care
- Author
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Newton-Levinson, Anna, Blake, Sarah C, Swartzendruber, Andrea, Kramer, Michael R, and Sales, Jessica M
- Published
- 2024
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49. Holy Ignorance: When Religion and Culture Part Ways by Olivier Roy (review)
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Kramer, Michael P.
- Published
- 2015
50. Neighborhood deprivation in relation to ovarian reserve and outcomes of ovarian stimulation among oocyte donors
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Suresh, Tanvi, LaPointe, Sarah, Lee, Jaqueline C., Nagy, Zsolt P., Shapiro, Daniel B., Kramer, Michael R., Hipp, Heather S., and Gaskins, Audrey J.
- Published
- 2024
- Full Text
- View/download PDF
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