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1,104 results on '"Brown, Gregory P"'

3. ERK hyperactivation serves as a unified mechanism of escape in intrinsic and acquired CDK4/6 inhibitor resistance in acral lentiginous melanoma

Author

Jagirdar, Kasturee, Portuallo, Marie E., Wei, Meihan, Wilhide, Matthew, Bravo Narula, Jeremy A., Robertson, Bailey M., Alicea, Gretchen M., Aguh, Crystal, Xiao, Min, Godok, Tetiana, Fingerman, Dylan, Brown, Gregory Schuyler, Herlyn, Meenhard, Elad, Vissy M., Guo, Xinyu, Toska, Eneda, Zabransky, Daniel J., Wubbenhorst, Bradley, Nathanson, Katherine L., Kwatra, Shawn, Goyal, Yogesh, Ji, Hongkai, Liu, Qin, and Rebecca, Vito W.

Published
2024
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4. Altered Reinforcement Learning from Reward and Punishment in Anorexia Nervosa: Evidence from Computational Modeling

Author

Wierenga, Christina E, Reilly, Erin, Bischoff-Grethe, Amanda, Kaye, Walter H, and Brown, Gregory G

Subjects
Eating Disorders, Anorexia, Clinical Research, Brain Disorders, Behavioral and Social Science, Basic Behavioral and Social Science, Nutrition, Mental Health, Mental health, Good Health and Well Being, Humans, Punishment, Anorexia Nervosa, Reward, Computer Simulation, Affect, Eating disorders, prediction error, operant learning, decision-making, cognition, probabilistic associative learning, Medical and Health Sciences, Psychology and Cognitive Sciences, Experimental Psychology
Abstract

ObjectivesAnorexia nervosa (AN) is associated with altered sensitivity to reward and punishment. Few studies have investigated whether this results in aberrant learning. The ability to learn from rewarding and aversive experiences is essential for flexibly adapting to changing environments, yet individuals with AN tend to demonstrate cognitive inflexibility, difficulty set-shifting and altered decision-making. Deficient reinforcement learning may contribute to repeated engagement in maladaptive behavior.MethodsThis study investigated learning in AN using a probabilistic associative learning task that separated learning of stimuli via reward from learning via punishment. Forty-two individuals with Diagnostic and Statistical Manual of Mental Disorders (DSM)-5 restricting-type AN were compared to 38 healthy controls (HCs). We applied computational models of reinforcement learning to assess group differences in learning, thought to be driven by violations in expectations, or prediction errors (PEs). Linear regression analyses examined whether learning parameters predicted BMI at discharge.ResultsAN had lower learning rates than HC following both positive and negative PE (p

Published
2022

7. Detecting the Inverted-U in fMRI Studies of Schizophrenia: A Comparison of Three Analysis Methods.

Author

Thomas, Michael, Duffy, John, Swerdlow, Neal, Brown, Gregory, and Light, Gregory

Subjects
Confounds, Neuroimaging, Psychometrics, Schizophrenia, Working Memory, Humans, Magnetic Resonance Imaging, Memory, Short-Term, Parietal Lobe, Prefrontal Cortex, Schizophrenia
Abstract

OBJECTIVE: Cognitive tasks are used to probe neuronal activity during functional magnetic resonance imaging (fMRI) to detect signs of aberrant cognitive functioning in patients diagnosed with schizophrenia (SZ). However, nonlinear (inverted-U-shaped) associations between neuronal activity and task difficulty can lead to misinterpretation of group differences between patients and healthy comparison subjects (HCs). In this paper, we evaluated a novel method for correcting these misinterpretations based on conditional performance analysis. METHOD: Participants included 25 HCs and 27 SZs who performed a working memory (WM) task (N-back) with 5 load conditions while undergoing fMRI. Neuronal activity was regressed onto: 1) task load (i.e., parametric task levels), 2) marginal task performance (i.e., performance averaged over all load conditions), or 3) conditional task performance (i.e., performance within each load condition). RESULTS: In most regions of interest, conditional performance analysis uniquely revealed inverted-U-shaped neuronal activity in both SZs and HCs. After accounting for conditional performance differences between groups, we observed few difference in both the pattern and level of neuronal activity between SZs and HCs within regions that are classically associated with WM functioning (e.g., posterior dorsolateral prefrontal and parietal association cortices). However, SZs did show aberrant activity within the anterior dorsolateral prefrontal cortex. CONCLUSIONS: Interpretations of differences in neuronal activity between groups, and of associations between neuronal activity and performance, should be considered within the context of task performance. Whether conditional performance-based differences reflect compensation, dedifferentiation, or other processes is not a question that is easily resolved by examining activation and performance data alone.

Published
2022

8. High-resolution Laboratory Measurements of K-shell X-ray Line Polarization and Excitation Cross Sections in Heliumlike S XV Ions

Author

Shah, Chintan, Hell, Natalie, Hubbard, Antonia, Gu, Ming Feng, MacDonald, Michael J., Eckart, Megan E., Kelley, Richard L., Kilbourne, Caroline A., Leutenegger, Maurice A., Porter, F. Scott, and Brown, Gregory V.

Subjects
Physics - Atomic Physics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Physics - Plasma Physics
Abstract

We report measurements of electron-impact excitation cross sections for the strong K-shell n=2-1 transitions in S XV using the LLNL EBIT-I electron beam ion trap, two crystal spectrometers, and the EBIT Calorimeter Spectrometer. The cross sections are determined by direct normalization to the well known cross sections of radiative electron capture, measured simultaneously. Using contemporaneous polarization measurements with the two crystal spectrometers, whose dispersion planes are oriented parallel and perpendicular to the electron beam direction, the polarization of the direct excitation line emission is determined, and in turn the isotropic total cross sections are extracted. We further experimentally investigate various line-formation mechanisms, finding that radiative cascades and collisional inner-shell ionization dominate the degree of linear polarization and total line-emission cross sections of the forbidden line $z$., Comment: 16 Pages, 9 Figures, published in ApJ

Published
2021
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9. Observation of strong two-electron--one-photon transitions in few-electron ion

Author

Togawa, Moto, Kühn, Steffen, Shah, Chintan, Amaro, Pedro, Steinbrügge, René, Stierhof, Jakob, Hell, Natalie, Rosner, Michael, Fujii, Keisuke, Bissinger, Matthias, Ballhausen, Ralf, Hoesch, Moritz, Seltmann, Jörn, Park, SungNam, Grilo, Filipe, Porter, F. Scott, Santos, José Paulo, Chung, Moses, Stöhlker, Thomas, Wilms, Jörn, Pfeifer, Thomas, Brown, Gregory V., Leutenegger, Maurice A., Bernitt, Sven, and López-Urrutia, José R. Crespo

Subjects
Physics - Atomic Physics, Astrophysics - High Energy Astrophysical Phenomena, Physics - Plasma Physics
Abstract

We resonantly excite the $K$ series of O$^{5+}$ and O$^{6+}$ up to principal quantum number $n=11$ with monochromatic x rays, producing $K$-shell holes, and observe their relaxation by soft-x-ray emission. Some photoabsorption resonances of O$^{5+}$ reveal strong two-electron--one-photon (TEOP) transitions. We find that for the $[(1s\,2s)_1\,5p_{3/2}]_{3/2;1/2}$ states, TEOP relaxation is by far stronger than the radiative decay and competes with the usually much faster Auger decay path. This enhanced TEOP decay arises from a strong correlation with the near-degenerate upper states $[(1s\,2p_{3/2})_1\,4s]_{3/2;1/2}$ of a Li-like satellite blend of the He-like $K\alpha$ transition. Even in three-electron systems, TEOP transitions can play a dominant role, and the present results should guide further research on the ubiquitous and abundant many-electron ions where electronic energy degeneracies are far more common and configuration mixing is stronger., Comment: Published in PRA

Published
2020
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10. High Resolution Photoexcitation Measurements Exacerbate the Long-Standing Fe XVII Oscillator Strength Problem

Author

Kühn, Steffen, Shah, Chintan, López-Urrutia, José R. Crespo, Fujii, Keisuke, Steinbrügge, René, Stierhof, Jakob, Togawa, Moto, Harman, Zoltán, Oreshkina, Natalia S., Cheung, Charles, Kozlov, Mikhail G., Porsev, Sergey G., Safronova, Marianna S., Berengut, Julian C., Rosner, Michael, Bissinger, Matthias, Ballhausen, Ralf, Hell, Natalie, Park, SungNam, Chung, Moses, Hoesch, Moritz, Seltmann, Jörn, Surzhykov, Andrey S., Yerokhin, Vladimir A., Wilms, Jörn, Porter, F. Scott, Stöhlker, Thomas, Keitel, Christoph H., Pfeifer, Thomas, Brown, Gregory V., Leutenegger, Maurice A., and Bernitt, Sven

Subjects
Physics - Atomic Physics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Solar and Stellar Astrophysics, Physics - Plasma Physics
Abstract

For more than 40 years, most astrophysical observations and laboratory studies of two key soft x-ray diagnostic $2p-3d$ transitions, $3C$ and $3D$, in Fe XVII ions found oscillator strength ratios $f(3C)/f(3D)$ disagreeing with theory, but uncertainties had precluded definitive statements on this much studied conundrum. Here, we resonantly excite these lines using synchrotron radiation at PETRA III, and reach, at a millionfold lower photon intensities, a 10 times higher spectral resolution, and 3 times smaller uncertainty than earlier work. Our final result of $f(3C)/f(3D) = 3.09(8)(6)$ supports many of the earlier clean astrophysical and laboratory observations, while departing by five sigmas from our own newest large-scale ab initio calculations, and excluding all proposed explanations, including those invoking nonlinear effects and population transfers., Comment: Main text (6 pages, 3 figures), Supplmentary Material (8 pages, 4 figure), Published in Physical Review Letters

Published
2019
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12. How Much Water Is in a Mouthful, and How Many Mouthfuls Should I Drink? A Laboratory Exercise to Help Students Understand Developing a Hydration Plan

Author

Brown, Gregory A., Shaw, Brandon S., and Shaw, Ina

Abstract

Preventing impairments in athletic performance is an important concept for students that are preparing for careers that involve working with athletes. Gaining hands on, laboratory-based experience in measuring exercise induced dehydration can help students understand how to help athletes prevent dehydration induced impairment in performance. This article describes a laboratory exercise for junior and senior students in a sports nutrition class, in which the students measure changes in body mass (as a measure of dehydration) due to 40 min of moderate-intensity exercise and 40 min of vigorous-intensity exercise. The students also measure how much water is in a mouthful from a sports bottle and from a drinking fountain. The students then calculate how many mouthfuls are necessary to replace exercise induced fluid losses. This laboratory exercise has been well received by students and has improved performance on the test regarding hydration.

Published
2021
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13. Laboratory Calibrations of Fe XII-XIV Line-Intensity Ratios for Electron Density Diagnostics

Author

Arthanayaka, Thusitha P., Beiersdorfer, Peter, Brown, Gregory V., Gu, Ming Feng, Hahn, Michael, Hell, Natalie, Lockard, Tom E., and Savin, Daniel Wolf

Subjects
Astrophysics - Solar and Stellar Astrophysics, Physics - Atomic Physics
Abstract

We have used an electron beam ion trap to measure electron-density-diagnostic line-intensity ratios for extreme ultraviolet lines from F XII, XIII, and XIV at wavelengths of 185-205 255-276 Angstroms. These ratios can be used as density diagnostics for astrophysical spectra and are especially relevant to solar physics. We found that density diagnostics using the Fe XIII 196.53/202.04 and the Fe XIV 264.79/274.21 and 270.52A/274.21 line ratios are reliable using the atomic data calculated with the Flexible Atomic Code. On the other hand, we found a large discrepancy between the FAC theory and experiment for the commonly used Fe XII (186.85 + 186.88)/195.12 line ratio. These FAC theory calculations give similar results to the data tabulated in CHIANTI, which are commonly used to analyze solar observations. Our results suggest that the discrepancies seen between solar coronal density measurements using the Fe XII (186.85 + 186.88)/195.12 and Fe XIII 196.54/202.04 line ratios are likely due to issues with the atomic calculations for Fe XII.

Published
2019
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14. Chandra X-ray spectroscopy of the focused wind in the Cygnus X-1 system III. Dipping in the low/hard state

Author

Hirsch, Maria, Hell, Natalie, Grinberg, Victoria, Ballhausen, Ralf, Nowak, Michael A., Pottschmidt, Katja, Schulz, Norbert S., Dauser, Thomas, Hanke, Manfred, Kallman, Timothy R., Brown, Gregory V., and Wilms, Jörn

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present an analysis of three Chandra High Energy Transmission Gratings observations of the black hole binary Cyg X-1/HDE 226868 at different orbital phases. The stellar wind that is powering the accretion in this system is characterized by temperature and density inhomogeneities including structures, or "clumps", of colder, more dense material embedded in the photoionized gas. As these clumps pass our line of sight, absorption dips appear in the light curve. We characterize the properties of the clumps through spectral changes during various dip stages. Comparing the silicon and sulfur absorption line regions (1.6-2.7 keV $\equiv$ 7.7-4.6 {\AA}) in four levels of varying column depth reveals the presence of lower ionization stages, i.e., colder or denser material, in the deeper dip phases. The Doppler velocities of the lines are roughly consistent within each observation, varying with the respective orbital phase. This is consistent with the picture of a structure that consists of differently ionized material, in which shells of material facing the black hole shield the inner and back shells from the ionizing radiation. The variation of the Doppler velocities compared to a toy model of the stellar wind, however, does not allow us to pin down an exact location of the clump region in the system. This result, as well as the asymmetric shape of the observed lines, point at a picture of a complex wind structure., Comment: 19 pages, 15 figures, accepted for publication in A&A

Published
2019
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15. Unlocking the Capabilities of Future High-Resolution X-ray Spectroscopy Missions Through Laboratory Astrophysics

Author

Betancourt-Martinez, Gabriele, Akamatsu, Hiroki, Barret, Didier, Bautista, Manuel, Bernitt, Sven, Bianchi, Stefano, Bodewits, Dennis, Brickhouse, Nancy, Brown, Gregory V., Costantini, Elisa, Coreno, Marcello, López-Urrutia, José R. Crespo, Cumbee, Renata, Eckart, Megan, Ferland, Gary, Fiore, Fabrizio, Fogle, Michael, Foster, Adam, Garcia, Javier, Gorczyca, Tom, Grinberg, Victoria, Grosso, Nicolas, Gu, Liyi, Gu, Ming Feng, Guainazzi, Matteo, Hell, Natalie, Herder, Jan-Willem den, Kaastra, Jelle, Kallman, Timothy, Lee, Julia, Leutenegger, Maurice, Marler, Joan, McCammon, Dan, Nakashima, Shinya, Nicastro, Fabrizio, Paerels, Frits, Pajot, François, Pointecouteau, Etienne, Porquet, Delphine, Porter, F. Scott, Savin, Daniel Wolf, Sawada, Makoto, Shah, Chintan, Simionescu, Aurora, de Simone, Monica, Sosolik, Chad, Stancil, Phillip, Steinbrügge, René, and Yamaguchi, Hiroya

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract

Thanks to high-resolution and non-dispersive spectrometers onboard future X-ray missions such as XRISM and Athena, we are finally poised to answer important questions about the formation and evolution of galaxies and large-scale structure. However, we currently lack an adequate understanding of many atomic processes behind the spectral features we will soon observe. Large error bars on parameters as critical as transition energies and atomic cross sections can lead to unacceptable uncertainties in the calculations of e.g., elemental abundance, velocity, and temperature. Unless we address these issues, we risk limiting the full scientific potential of these missions. Laboratory astrophysics, which comprises theoretical and experimental studies of the underlying physics behind observable astrophysical processes, is therefore central to the success of these missions., Comment: Science white paper submitted to the Astro2020 Decadal Survey

Published
2019

16. Evidence for a novel subcortical mechanism for posterior cingulate cortex atrophy in HIV peripheral neuropathy

Author

Keltner, John R, Tong, Alan, Visser, Eelke, Jenkinson, Mark, Connolly, Colm G, Dasca, Alyssa, Sheringov, Aleks, Calvo, Zachary, Umbao, Earl, Mande, Rohit, Bilder, Mary Beth, Sahota, Gagandeep, Franklin, Donald R, Corkran, Stephanie, Grant, Igor, Archibald, Sarah, Vaida, Florin, Brown, Gregory G, Atkinson, J Hampton, Simmons, Alan N, and Ellis, Ronald J

Subjects
Biomedical and Clinical Sciences, Neurosciences, Clinical Sciences, Neurodegenerative, Peripheral Neuropathy, Pain Research, Chronic Pain, 2.1 Biological and endogenous factors, Aetiology, Neurological, Adult, Aged, Atrophy, Brain Mapping, Cross-Sectional Studies, Female, Gyrus Cinguli, HIV, HIV Infections, Humans, Magnetic Resonance Imaging, Male, Middle Aged, Neuralgia, Paresthesia, Peripheral Nervous System Diseases, Thalamus, White Matter, Brain, Imaging, Peripheral neuropathy, CHARTER Group, Medical Microbiology, Virology, Clinical sciences, Medical microbiology
Abstract

We previously reported that neuropathic pain was associated with smaller posterior cingulate cortical (PCC) volumes, suggesting that a smaller/dysfunctional PCC may contribute to development of pain via impaired mind wandering. A gap in our previous report was lack of evidence for a mechanism for the genesis of PCC atrophy in HIV peripheral neuropathy. Here we investigate if volumetric differences in the subcortex for those with neuropathic paresthesia may contribute to smaller PCC volumes, potentially through deafferentation of ascending white matter tracts resulting from peripheral nerve damage in HIV neuropathy. Since neuropathic pain and paresthesia are highly correlated, statistical decomposition was used to separate pain and paresthesia symptoms to determine which regions of brain atrophy are associated with both pain and paresthesia and which are associated separately with pain or paresthesia. HIV+ individuals (N = 233) with and without paresthesia in a multisite study underwent structural brain magnetic resonance imaging. Voxel-based morphometry and a segmentation/registration tool were used to investigate regional brain volume changes associated with paresthesia. Analysis of decomposed variables found that smaller midbrain and thalamus volumes were associated with paresthesia rather than pain. However, atrophy in the PCC was related to both pain and paresthesia. Peak thalamic atrophy (p = 0.004; MNI x = - 14, y = - 24, z = - 2) for more severe paresthesia was in a region with reciprocal connections with the PCC. This provides initial evidence that smaller PCC volumes in HIV peripheral neuropathy are related to ascending white matter deafferentation caused by small fiber damage observed in HIV peripheral neuropathy.

Published
2020

17. Detection of polarized gamma-ray emission from the Crab nebula with Hitomi Soft Gamma-ray Detector

Author

Hitomi Collaboration, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W., Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W., Blandford, Roger, Brenneman, Laura W., Brown, Gregory V., Bulbul, Esra, Cackett, Edward M., Chernyakova, Maria, Chiao, Meng P., Coppi, Paolo S., Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P., Herder, Jan-Willem den, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E., Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C., Ferrigno, Carlo, Foster, Adam R., Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C., Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M., Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S., Hornschemeier, Ann, Hoshino, Akio, Hughes, John P., Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L., Kilbourne, Caroline A., Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A., Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A., Limousin, Olivier, Loewenstein, Michael, Long, Knox S., Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R., Mehdipour, Missagh, Miller, Eric D., Miller, Jon M., Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F., Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K., Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stephane, Petre, Robert, Pinto, Ciro, Porter, Frederick S., Pottschmidt, Katja, Reynolds, Christopher S., Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J., Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K., Soong, Yang, Stawarz, Lukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shin'ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T., Tashiro, Makoto S., Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shin'ichiro, Urry, C. Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R., Williams, Brian J., Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y., Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, Zoghbi, Abderahmen, and Uchida, Yuusuke

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present the results from the Hitomi Soft Gamma-ray Detector (SGD) observation of the Crab nebula. The main part of SGD is a Compton camera, which in addition to being a spectrometer, is capable of measuring polarization of gamma-ray photons. The Crab nebula is one of the brightest X-ray / gamma-ray sources on the sky, and, the only source from which polarized X-ray photons have been detected. SGD observed the Crab nebula during the initial test observation phase of Hitomi. We performed the data analysis of the SGD observation, the SGD background estimation and the SGD Monte Carlo simulations, and, successfully detected polarized gamma-ray emission from the Crab nebula with only about 5 ks exposure time. The obtained polarization fraction of the phase-integrated Crab emission (sum of pulsar and nebula emissions) is (22.1 $\pm$ 10.6)% and, the polarization angle is 110.7$^o$ + 13.2 / $-$13.0$^o$ in the energy range of 60--160 keV (The errors correspond to the 1 sigma deviation). The confidence level of the polarization detection was 99.3%. The polarization angle measured by SGD is about one sigma deviation with the projected spin axis of the pulsar, 124.0$^o$ $\pm$0.1$^o$., Comment: 19 pages, 18 figures, 6 tables. Accepted for publication in PASJ

Published
2018
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23. Laboratory Measurements of X-Ray Emission from Highly Charged Argon Ions

Author

Bulbul, Esra, Foster, Adam, Brown, Gregory V., Bautz, Mark W., Beiersdorfer, Peter, Hell, Natalie, Kilbourne, Caroline, Kraft, Ralph, Kelley, Richard, Leutenegger, Maurice A., Miller, Eric D., Porter, F. Scott, and Smith, Randall K.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Uncertainties in atomic models will introduce noticeable additional systematics in calculating the flux of weak dielectronic recombination (DR) satellite lines, affecting the detection and flux measurements of other weak spectral lines. One important example is the Ar XVII He-beta DR, which is expected to be present in emission from the hot intracluster medium (ICM) of galaxy clusters and could impact measurements of the flux of the 3.5 keV line that has been suggested as a secondary emission from a dark matter interaction. We perform a set of experiments using the Lawrence Livermore National Laboratory's electron beam ion trap (EBIT-I) and the X-Ray Spectrometer quantum calorimeter (XRS/EBIT), to test the Ar XVII He-beta DR origin of the 3.5 keV line. We measured the X-ray emission following resonant DR onto helium-like and lithium-like Argon using EBIT-I's Maxwellian simulator mode at a simulated electron temperature of Te=1.74 keV. The measured flux of the Ar XVII He-beta DR lined is too weak to account for the flux in the 3.5 keV line assuming reasonable plasma parameters. We, therefore, rule out Ar XVII He-beta DR as a significant contributor to the 3.5 keV line. A comprehensive comparison between the atomic theory and the EBIT experiment results is also provided., Comment: Accepted for publication in ApJ. 11 pages, 5 figures

Published
2018
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24. Hitomi X-ray Observation of the Pulsar Wind Nebula G21.5$-$0.9

Author

Hitomi Collaboration, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W., Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W., Blandford, Roger, Brenneman, Laura W., Brown, Gregory V., Bulbul, Esra, Cackett, Edward M., Chernyakova, Maria, Chiao, Meng P., Coppi, Paolo S., Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P., Herder, Jan-Willem den, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E., Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C., Ferrigno, Carlo, Foster, Adam R., Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C., Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M., Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S., Hornschemeier, Ann, Hoshino, Akio, Hughes, John P., Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L., Kilbourne, Caroline A., Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A., Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A., Limousin, Olivier, Loewenstein, Michael, Long, Knox S., Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R., Mehdipour, Missagh, Miller, Eric D., Miller, Jon M., Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F., Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K., Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S., Pottschmidt, Katja, Reynolds, Christopher S., Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sato, Toshiki, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J., Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K., Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shin'ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T., Tashiro, Makoto S., Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shin'ichiro, Urry, C. Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R., Williams, Brian J., Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y., Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, Zoghbi, Abderahmen, Nakaniwa, Nozomu, Murakami, Hiroaki, and Guest, Benson

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present results from the Hitomi X-ray observation of a young composite-type supernova remnant (SNR) G21.5$-$0.9, whose emission is dominated by the pulsar wind nebula (PWN) contribution. The X-ray spectra in the 0.8-80 keV range obtained with the Soft X-ray Spectrometer (SXS), Soft X-ray Imager (SXI) and Hard X-ray Imager (HXI) show a significant break in the continuum as previously found with the NuSTAR observation. After taking into account all known emissions from the SNR other than the PWN itself, we find that the Hitomi spectra can be fitted with a broken power law with photon indices of $\Gamma_1=1.74\pm0.02$ and $\Gamma_2=2.14\pm0.01$ below and above the break at $7.1\pm0.3$ keV, which is significantly lower than the NuSTAR result ($\sim9.0$ keV). The spectral break cannot be reproduced by time-dependent particle injection one-zone spectral energy distribution models, which strongly indicates that a more complex emission model is needed, as suggested by recent theoretical models. We also search for narrow emission or absorption lines with the SXS, and perform a timing analysis of PSR J1833$-$1034 with the HXI and SGD. No significant pulsation is found from the pulsar. However, unexpectedly, narrow absorption line features are detected in the SXS data at 4.2345 keV and 9.296 keV with a significance of 3.65 $\sigma$. While the origin of these features is not understood, their mere detection opens up a new field of research and was only possible with the high resolution, sensitivity and ability to measure extended sources provided by an X-ray microcalorimeter., Comment: 16 pages, 8 figures, 4 tables. Accepted for publication in PASJ

Published
2018
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25. Temperature Structure in the Perseus Cluster Core Observed with Hitomi

Author

Hitomi Collaboration, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W., Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W., Blandford, Roger, Brenneman, Laura W., Brown, Gregory V., Bulbul, Esra, Cackett, Edward M., Chernyakova, Maria, Chiao, Meng P., Coppi, Paolo S., Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P., Herder, Jan-Willem den, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E., Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C., Ferrigno, Carlo, Foster, Adam R., Fujimoto, Ryuichi, Fukazawa, Yasushi, Furukawa, Maki, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C., Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M., Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S., Hornschemeier, Ann, Hoshino, Akio, Hughes, John P., Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Kato, Yuichi, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L., Kilbourne, Caroline A., Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A., Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A., Limousin, Olivier, Loewenstein, Michael, Long, Knox S., Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R., Mehdipour, Missagh, Miller, Eric D., Miller, Jon M., Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F., Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K., Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S., Pottschmidt, Katja, Reynolds, Christopher S., Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J., Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K., Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shiníchiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T., Tashiro, Makoto S., Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shiníchiro, Urry, C. Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R., Williams, Brian J., Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y., Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, and Zoghbi, Abderahmen

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The present paper investigates the temperature structure of the X-ray emitting plasma in the core of the Perseus cluster using the 1.8--20.0 keV data obtained with the Soft X-ray Spectrometer (SXS) onboard the Hitomi Observatory. A series of four observations were carried out, with a total effective exposure time of 338 ks and covering a central region $\sim7'$ in diameter. The SXS was operated with an energy resolution of $\sim$5 eV (full width at half maximum) at 5.9 keV. Not only fine structures of K-shell lines in He-like ions but also transitions from higher principal quantum numbers are clearly resolved from Si through Fe. This enables us to perform temperature diagnostics using the line ratios of Si, S, Ar, Ca, and Fe, and to provide the first direct measurement of the excitation temperature and ionization temperature in the Perseus cluster. The observed spectrum is roughly reproduced by a single temperature thermal plasma model in collisional ionization equilibrium, but detailed line ratio diagnostics reveal slight deviations from this approximation. In particular, the data exhibit an apparent trend of increasing ionization temperature with increasing atomic mass, as well as small differences between the ionization and excitation temperatures for Fe, the only element for which both temperatures can be measured. The best-fit two-temperature models suggest a combination of 3 and 5 keV gas, which is consistent with the idea that the observed small deviations from a single temperature approximation are due to the effects of projection of the known radial temperature gradient in the cluster core along the line of sight. Comparison with the Chandra/ACIS and the XMM-Newton/RGS results on the other hand suggests that additional lower-temperature components are present in the ICM but not detectable by Hitomi SXS given its 1.8--20 keV energy band., Comment: 29 pages, 19 figures, 9 tables. Accepted for publication in PASJ

Published
2017
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26. Atomic data and spectral modeling constraints from high-resolution X-ray observations of the Perseus cluster with Hitomi

Author

Hitomi Collaboration, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W., Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W., Blandford, Roger, Brenneman, Laura W., Brown, Gregory V., Bulbul, Esra, Cackett, Edward M., Chernyakova, Maria, Chiao, Meng P., Coppi, Paolo S., Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P., Herder, Jan-Willem den, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E., Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C., Ferrigno, Carlo, Foster, Adam R., Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C., Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M., Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hell, Natalie, Hiraga, Junko S., Hornschemeier, Ann, Hoshino, Akio, Hughes, John P., Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L., Kilbourne, Caroline A., Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A., Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A., Limousin, Olivier, Loewenstein, Michael, Long, Knox S., Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R., Mehdipour, Missagh, Miller, Eric D., Miller, Jon M., Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F., Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K., Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S., Pottschmidt, Katja, Reynolds, Christopher S., Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J., Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K., Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shin'ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T., Tashiro, Makoto S., Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shin'ichiro, Urry, C. Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R., Williams, Brian J., Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y., Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, Zoghbi, Abderahmen, and Raassen, A. J. J.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The Hitomi SXS spectrum of the Perseus cluster, with $\sim$5 eV resolution in the 2-9 keV band, offers an unprecedented benchmark of the atomic modeling and database for hot collisional plasmas. It reveals both successes and challenges of the current atomic codes. The latest versions of AtomDB/APEC (3.0.8), SPEX (3.03.00), and CHIANTI (8.0) all provide reasonable fits to the broad-band spectrum, and are in close agreement on best-fit temperature, emission measure, and abundances of a few elements such as Ni. For the Fe abundance, the APEC and SPEX measurements differ by 16%, which is 17 times higher than the statistical uncertainty. This is mostly attributed to the differences in adopted collisional excitation and dielectronic recombination rates of the strongest emission lines. We further investigate and compare the sensitivity of the derived physical parameters to the astrophysical source modeling and instrumental effects. The Hitomi results show that an accurate atomic code is as important as the astrophysical modeling and instrumental calibration aspects. Substantial updates of atomic databases and targeted laboratory measurements are needed to get the current codes ready for the data from the next Hitomi-level mission., Comment: 46 pages, 25 figures, 11 tables. Accepted for publication in PASJ

Published
2017
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27. Hitomi Observations of the LMC SNR N132D: Highly Redshifted X-ray Emission from Iron Ejecta

Author

Hitomi Collaboration, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W., Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W., Blandford, Roger, Brenneman, Laura W., Brown, Gregory V., Bulbul, Esra, Cackett, Edward M., Chernyakova, Maria, Chiao, Meng P., Coppi, Paolo S., Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P., Herder, Jan-Willem den, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E., Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C., Ferrigno, Carlo, Foster, Adam R., Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C., Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M., Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S., Hornschemeier, Ann, Hoshino, Akio, Hughes, John P., Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L., Kilbourne, Caroline A., Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A., Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A., Limousin, Olivier, Loewenstein, Michael, Long, Knox S., Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R., Mehdipour, Missagh, Miller, Eric D., Miller, Jon M., Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F., Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K., Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S., Pottschmidt, Katja, Reynolds, Christopher S., Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sato, Toshiki, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J., Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K., Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shin'ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T., Tashiro, Makoto S., Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shin'ichiro, Urry, C. Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R., Williams, Brian J., Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y., Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, and Zoghbi, Abderahmen

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present Hitomi observations of N132D, a young, X-ray bright, O-rich core-collapse supernova remnant in the Large Magellanic Cloud (LMC). Despite a very short observation of only 3.7 ks, the Soft X-ray Spectrometer (SXS) easily detects the line complexes of highly ionized S K and Fe K with 16-17 counts in each. The Fe feature is measured for the first time at high spectral resolution. Based on the plausible assumption that the Fe K emission is dominated by He-like ions, we find that the material responsible for this Fe emission is highly redshifted at ~800 km/s compared to the local LMC interstellar medium (ISM), with a 90% credible interval of 50-1500 km/s if a weakly informative prior is placed on possible line broadening. This indicates (1) that the Fe emission arises from the supernova ejecta, and (2) that these ejecta are highly asymmetric, since no blue-shifted component is found. The S K velocity is consistent with the local LMC ISM, and is likely from swept-up ISM material. These results are consistent with spatial mapping that shows the He-like Fe concentrated in the interior of the remnant and the S tracing the outer shell. The results also show that even with a very small number of counts, direct velocity measurements from Doppler-shifted lines detected in extended objects like supernova remnants are now possible. Thanks to the very low SXS background of ~1 event per spectral resolution element per 100 ks, such results are obtainable during short pointed or slew observations with similar instruments. This highlights the power of high-spectral-resolution imaging observations, and demonstrates the new window that has been opened with Hitomi and will be greatly widened with future missions such as the X-ray Astronomy Recovery Mission (XARM) and Athena., Comment: 18 pages, 15 figures, 1 table. Accepted for publication by PASJ

Published
2017
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28. Glimpse of the highly obscured HMXB IGR J16318-4848 with Hitomi

Author

Hitomi Collaboration, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W., Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W., Blandford, Roger, Brenneman, Laura W., Brown, Gregory V., Bulbul, Esra, Cackett, Edward M., Chernyakova, Maria, Chiao, Meng P., Coppi, Paolo S., Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P., Herder, Jan-Willem den, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E., Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C., Ferrigno, Carlo, Foster, Adam R., Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C., Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M., Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S., Hornschemeier, Ann, Hoshino, Akio, Hughes, John P., Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L., Kilbourne, Caroline A., Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A., Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A., Limousin, Olivier O., Loewenstein, Michael, Long, Knox S., Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R., Mehdipour, Missagh, Miller, Eric D., Miller, Jon M., Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F., Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K., Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S., Pottschmidt, Katja, Reynolds, Christopher S., Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemitsos, Peter J., Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K., Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shin'ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T., Tashiro, Makoto S., Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shin'ichiro, Urry, C. Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R., Williams, Brian J., Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y., Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, Zoghbi, Abderahmen, and Nakaniwa, Nozomi

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report a Hitomi observation of IGR J16318-4848, a high-mass X-ray binary system with an extremely strong absorption of N_H~10^{24} cm^{-2}. Previous X-ray studies revealed that its spectrum is dominated by strong fluorescence lines of Fe as well as continuum emission. For physical and geometrical insight into the nature of the reprocessing material, we utilize the high spectroscopic resolving power of the X-ray microcalorimeter (the soft X-ray spectrometer; SXS) and the wide-band sensitivity by the soft and hard X-ray imager (SXI and HXI) aboard Hitomi. Even though photon counts are limited due to unintended off-axis pointing, the SXS spectrum resolves Fe K{\alpha_1} and K{\alpha_2} lines and puts strong constraints on the line centroid and width. The line width corresponds to the velocity of 160^{+300}_{-70} km s^{-1}. This represents the most accurate, and smallest, width measurement of this line made so far from any X-ray binary, much less than the Doppler broadening and shift expected from speeds which are characteristic of similar systems. Combined with the K-shell edge energy measured by the SXI and HXI spectra, the ionization state of Fe is estimated to be in the range of Fe I--IV. Considering the estimated ionization parameter and the distance between the X-ray source and the absorber, the density and thickness of the materials are estimated. The extraordinarily strong absorption and the absence of a Compton shoulder component is confirmed. These characteristics suggest reprocessing materials which are distributed in a narrow solid angle or scattering primarily with warm free electrons or neutral hydrogen., Comment: 17 pages, 9 figures, 2 tables, accepted for publication in PASJ

Published
2017
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29. Hitomi Observation of Radio Galaxy NGC 1275: The First X-ray Microcalorimeter Spectroscopy of Fe-K{\alpha} Line Emission from an Active Galactic Nucleus

Author

Hitomi Collaboration, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W., Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W., Blandford, Roger, Brenneman, Laura W., Brown, Gregory V., Bulbul, Esra, Cackett, Edward M., Chernyakova, Maria, Chiao, Meng P., Coppi, Paolo S., Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P., Herder, Jan-Willem den, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E., Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C., Ferrigno, Carlo, Foster, Adam R., Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C., Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M., Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S., Hornschemeier, Ann, Hoshino, Akio, Hughes, John P., Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L., Kilbourne, Caroline A., Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A., Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A., Limousin, Olivier O., Loewenstein, Michael, Long, Knox S., Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R., Mehdipour, Missagh, Miller, Eric D., Miller, Jon M., Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F., Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K., Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S., Pottschmidt, Katja, Reynolds, Christopher S., Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemitsos, Peter J., Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K., Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shin'ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T., Tashiro, Makoto S., Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shin'ichiro, Urry, C. Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R., Williams, Brian J., Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y., Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, Zoghbi, Abderahmen, and Kawamuro, Taiki

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The origin of the narrow Fe-K{\alpha} fluorescence line at 6.4 keV from active galactic nuclei has long been under debate; some of the possible sites are the outer accretion disk, the broad line region, a molecular torus, or interstellar/intracluster media. In February-March 2016, we performed the first X-ray microcalorimeter spectroscopy with the Soft X-ray Spectrometer (SXS) onboard the Hitomi satellite of the Fanaroff-Riley type I radio galaxy NGC 1275 at the center of the Perseus cluster of galaxies. With the high energy resolution of ~5 eV at 6 keV achieved by Hitomi/SXS, we detected the Fe-K{\alpha} line with ~5.4 {\sigma} significance. The velocity width is constrained to be 500-1600 km s$^{-1}$ (FWHM for Gaussian models) at 90% confidence. The SXS also constrains the continuum level from the NGC 1275 nucleus up to ~20 keV, giving an equivalent width ~20 eV of the 6.4 keV line. Because the velocity width is narrower than that of broad H{\alpha} line of ~2750 km s$^{-1}$, we can exclude a large contribution to the line flux from the accretion disk and the broad line region. Furthermore, we performed pixel map analyses on the Hitomi/SXS data and image analyses on the Chandra archival data, and revealed that the Fe-K{\alpha} line comes from a region within ~1.6 kpc from the NGC 1275 core, where an active galactic nucleus emission dominates, rather than that from intracluster media. Therefore, we suggest that the source of the Fe-K{\alpha} line from NGC 1275 is likely a low-covering fraction molecular torus or a rotating molecular disk which probably extends from a pc to hundreds pc scale in the active galactic nucleus system., Comment: 20 pages, 8 figures, 6 tables, accepted for publication in PASJ

Published
2017
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30. Atmospheric gas dynamics in the Perseus cluster observed with Hitomi

Author

Hitomi Collaboration, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W., Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W., Blandford, Roger, Brenneman, Laura W., Brown, Gregory V., Bulbul, Esra, Cackett, Edward M., Canning, Rebecca E. A., Chernyakova, Maria, Chiao, Meng P., Coppi, Paolo S., Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P., Herder, Jan-Willem den, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E., Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C., Ferrigno, Carlo, Foster, Adam R., Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C., Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M., Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashi, Tasuku, Hayashida, Kiyoshi, Hiraga, Junko S., Hornschemeier, Ann, Hoshino, Akio, Hughes, John P., Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Shota, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L., Kilbourne, Caroline A., Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A., Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A., Limousin, Olivier, Loewenstein, Michael, Long, Knox S., Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R., Mehdipour, Missagh, Miller, Eric D., Miller, Jon M., Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F., Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K., Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S., Pottschmidt, Katja, Reynolds, Christopher S., Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J., Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K., Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shin'ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Keigo, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T., Tashiro, Makoto S., Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shin'ichiro, Urry, C. Megan, Ursino, Eugenio, Wang, Qian H. S., Watanabe, Shin, Werner, Norbert, Wilkins, Dan R., Williams, Brian J., Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y., Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, and Zoghbi, Abderahmen

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Extending the earlier measurements reported in Hitomi collaboration (2016, Nature, 535, 117), we examine the atmospheric gas motions within the central 100~kpc of the Perseus cluster using observations obtained with the Hitomi satellite. After correcting for the point spread function of the telescope and using optically thin emission lines, we find that the line-of-sight velocity dispersion of the hot gas is remarkably low and mostly uniform. The velocity dispersion reaches maxima of approximately 200~km~s$^{-1}$ toward the central active galactic nucleus (AGN) and toward the AGN inflated north-western `ghost' bubble. Elsewhere within the observed region, the velocity dispersion appears constant around 100~km~s$^{-1}$. We also detect a velocity gradient with a 100~km~s$^{-1}$ amplitude across the cluster core, consistent with large-scale sloshing of the core gas. If the observed gas motions are isotropic, the kinetic pressure support is less than 10\% of the thermal pressure support in the cluster core. The well-resolved optically thin emission lines have Gaussian shapes, indicating that the turbulent driving scale is likely below 100~kpc, which is consistent with the size of the AGN jet inflated bubbles. We also report the first measurement of the ion temperature in the intracluster medium, which we find to be consistent with the electron temperature. In addition, we present a new measurement of the redshift to the brightest cluster galaxy NGC~1275., Comment: 52 pages, 16 figures, 8 tables, accepted for publication in PASJ

Published
2017
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31. Latent Variable Modeling and Adaptive Testing for Experimental Cognitive Psychopathology Research

Author

Thomas, Michael L., Brown, Gregory G., Patt, Virginie M., and Duffy, John R.

Abstract

The adaptation of experimental cognitive tasks into measures that can be used to quantify neurocognitive outcomes in translational studies and clinical trials has become a key component of the strategy to address psychiatric and neurological disorders. Unfortunately, while most experimental cognitive tests have strong theoretical bases, they can have poor psychometric properties, leaving them vulnerable to measurement challenges that undermine their use in applied settings. Item response theory-based computerized adaptive testing has been proposed as a solution but has been limited in experimental and translational research due to its large sample requirements. We present a generalized latent variable model that, when combined with strong parametric assumptions based on mathematical cognitive models, permits the use of adaptive testing without large samples or the need to precalibrate item parameters. The approach is demonstrated using data from a common measure of working memory--the N-back task--collected across a diverse sample of participants. After evaluating dimensionality and model fit, we conducted a simulation study to compare adaptive versus nonadaptive testing. Computerized adaptive testing either made the task 36% more efficient or score estimates 23% more precise, when compared to nonadaptive testing. This proof-of-concept study demonstrates that latent variable modeling and adaptive testing can be used in experimental cognitive testing even with relatively small samples. Adaptive testing has the potential to improve the impact and replicability of findings from translational studies and clinical trials that use experimental cognitive tasks as outcome measures.

Published
2021
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32. Early adolescent brain markers of late adolescent academic functioning

Author

Meruelo, Alejandro Daniel, Jacobus, Joanna, Idy, Erick, Nguyen-Louie, Tam, Brown, Gregory, and Tapert, Susan Frances

Subjects
Biological Psychology, Psychology, Neurosciences, Pediatric, Clinical Research, 4.2 Evaluation of markers and technologies, Detection, screening and diagnosis, Neurological, Academic Success, Adolescent, Bayes Theorem, Biomarkers, Brain, Brain Mapping, Cerebral Cortex, Child, Cognition, Female, Forecasting, Humans, Intelligence Tests, Magnetic Resonance Imaging, Male, Sensitivity and Specificity, naive Bayesian classifier, Academic performance, Adolescence, Magnetic resonance imaging, Cortical thickness, naïve Bayesian classifier, Medical and Health Sciences, Psychology and Cognitive Sciences, Experimental Psychology, Biomedical and clinical sciences, Health sciences
Abstract

Academic performance in adolescence strongly influences adult prospects. Intelligence quotient (IQ) has historically been considered a strong predictor of academic performance. Less objectively explored have been morphometric features. We analyzed brain MRI morphometry metrics in early adolescence (age 12-14 years) as quantitative predictors of academic performance over high school using a naïve Bayesian classifier approach with n = 170 subjects. Based on the mean GPA, subjects were divided into high (GPA ≥3.54; n = 87) and low (GPA

Published
2019

33. Salience–Default Mode Functional Network Connectivity Linked to Positive and Negative Symptoms of Schizophrenia

Author

Hare, Stephanie M, Ford, Judith M, Mathalon, Daniel H, Damaraju, Eswar, Bustillo, Juan, Belger, Aysenil, Lee, Hyo Jong, Mueller, Bryon A, Lim, Kelvin O, Brown, Gregory G, Preda, Adrian, van Erp, Theo GM, Potkin, Steven G, Calhoun, Vince D, and Turner, Jessica A

Subjects
Brain Disorders, Mental Health, Neurosciences, Schizophrenia, Mental health, Good Health and Well Being, Adult, Connectome, Female, Humans, Magnetic Resonance Imaging, Male, Middle Aged, Nerve Net, ICA, salience network, default mode network, positive symptoms, negative symptoms, resting-state fMRI, Medical and Health Sciences, Psychology and Cognitive Sciences, Psychiatry
Abstract

Schizophrenia is a complex, debilitating mental disorder characterized by wide-ranging symptoms including delusions, hallucinations (so-called positive symptoms), and impaired motor and speech/language production (so-called negative symptoms). Salience-monitoring theorists propose that abnormal functional communication between the salience network (SN) and default mode network (DMN) begets positive and negative symptoms of schizophrenia, yet prior studies have predominately reported links between disrupted SN/DMN functional communication and positive symptoms. It remains unclear whether disrupted SN/DMN functional communication explains (1) solely positive symptoms or (2) both positive and negative symptoms of schizophrenia. To address this question, we incorporate time-lag-shifted functional network connectivity (FNC) analyses that explored coherence of the resting-state functional magnetic resonance imaging signal of 3 networks (anterior DMN, posterior DMN, and SN) with fixed time lags introduced between network time series (1 TR = 2 s; 2 TR = 4 s). Multivariate linear regression analysis revealed that severity of disordered thought and attentional deficits were negatively associated with 2 TR-shifted FNC between anterior DMN and posterior DMN. Meanwhile, severity of flat affect and bizarre behavior were positively associated with 1 TR-shifted FNC between anterior DMN and SN. These results provide support favoring the hypothesis that lagged SN/DMN functional communication is associated with both positive and negative symptoms of schizophrenia.

Published
2019

34. The Relationship Between Regional Cerebral Blood Flow Estimates and Alcohol Problems at 5‐Year Follow‐Up: The Role of Level of Response

Author

Courtney, Kelly E, Infante, Maria Alejandra, Brown, Gregory G, Tapert, Susan F, Simmons, Alan N, Smith, Tom L, and Schuckit, Marc A

Subjects
Biological Psychology, Biomedical and Clinical Sciences, Psychology, Substance Misuse, Clinical Research, Neurosciences, Alcoholism, Alcohol Use and Health, Mental health, Good Health and Well Being, Adolescent, Adult, Alcoholism, Brain, Cerebrovascular Circulation, Female, Follow-Up Studies, Humans, Magnetic Resonance Imaging, Male, Self Report, Time Factors, Young Adult, Cerebral Blood Flow, Level of Response, Alcohol Problems, Arterial Spin Labeling, Young Adults, Clinical Sciences, Substance Abuse, Clinical sciences, Biological psychology, Clinical and health psychology
Abstract

BackgroundAcute alcohol consumption is associated with temporarily increased regional cerebral blood flow (CBF). The extent of this increase appears to be moderated by individual differences in the level of response (LR) to alcohol's subjective effects. The low LR phenotype is a known risk factor for the development of alcohol problems. This study investigates how the low LR phenotype relates to the relationship between alcohol-related changes in CBF and alcohol problems 5 years later.MethodsYoung adults (ages 18 to 25) were selected based on their LR to alcohol and underwent a neuroimaging protocol including arterial spin labeling and functional scans. These participants were recontacted ~5 years later and assessed on alcohol outcomes. A final sample of 107 subjects (54 low and 53 high LR subjects) was included in the analyses. Whole-brain analysis revealed 5 clusters of significant alcohol-induced, versus placebo-induced, CBF changes that were consistent with a previous report. Peak alcohol-placebo CBF response was extracted from these regions and, along with the LR group, submitted to a hierarchical linear regression predicting alcohol problems. Analyses controlled for age, sex, and baseline alcohol problems.ResultsIn the regression analysis, greater alcohol-placebo CBF difference in the right middle/superior/inferior frontal gyri and bilateral anterior cingulate gyri clusters predicted greater future alcohol problems for the low LR group, whereas this relationship was not found to be significant in the high LR group.ConclusionsThis study demonstrates a clinically important relationship between CBF and future alcohol problems, particularly in individuals with a low LR phenotype. These initial results help to elucidate the neurobiological pathways involved in the development of alcohol use disorders for individuals with low LR.

Published
2019

35. Cortical Brain Abnormalities in 4474 Individuals With Schizophrenia and 5098 Control Subjects via the Enhancing Neuro Imaging Genetics Through Meta Analysis (ENIGMA) Consortium.

Author

van Erp, Theo GM, Walton, Esther, Hibar, Derrek P, Schmaal, Lianne, Jiang, Wenhao, Glahn, David C, Pearlson, Godfrey D, Yao, Nailin, Fukunaga, Masaki, Hashimoto, Ryota, Okada, Naohiro, Yamamori, Hidenaga, Bustillo, Juan R, Clark, Vincent P, Agartz, Ingrid, Mueller, Bryon A, Cahn, Wiepke, de Zwarte, Sonja MC, Hulshoff Pol, Hilleke E, Kahn, René S, Ophoff, Roel A, van Haren, Neeltje EM, Andreassen, Ole A, Dale, Anders M, Doan, Nhat Trung, Gurholt, Tiril P, Hartberg, Cecilie B, Haukvik, Unn K, Jørgensen, Kjetil N, Lagerberg, Trine V, Melle, Ingrid, Westlye, Lars T, Gruber, Oliver, Kraemer, Bernd, Richter, Anja, Zilles, David, Calhoun, Vince D, Crespo-Facorro, Benedicto, Roiz-Santiañez, Roberto, Tordesillas-Gutiérrez, Diana, Loughland, Carmel, Carr, Vaughan J, Catts, Stanley, Cropley, Vanessa L, Fullerton, Janice M, Green, Melissa J, Henskens, Frans A, Jablensky, Assen, Lenroot, Rhoshel K, Mowry, Bryan J, Michie, Patricia T, Pantelis, Christos, Quidé, Yann, Schall, Ulrich, Scott, Rodney J, Cairns, Murray J, Seal, Marc, Tooney, Paul A, Rasser, Paul E, Cooper, Gavin, Shannon Weickert, Cynthia, Weickert, Thomas W, Morris, Derek W, Hong, Elliot, Kochunov, Peter, Beard, Lauren M, Gur, Raquel E, Gur, Ruben C, Satterthwaite, Theodore D, Wolf, Daniel H, Belger, Aysenil, Brown, Gregory G, Ford, Judith M, Macciardi, Fabio, Mathalon, Daniel H, O'Leary, Daniel S, Potkin, Steven G, Preda, Adrian, Voyvodic, James, Lim, Kelvin O, McEwen, Sarah, Yang, Fude, Tan, Yunlong, Tan, Shuping, Wang, Zhiren, Fan, Fengmei, Chen, Jingxu, Xiang, Hong, Tang, Shiyou, Guo, Hua, Wan, Ping, Wei, Dong, Bockholt, Henry J, Ehrlich, Stefan, Wolthusen, Rick PF, King, Margaret D, Shoemaker, Jody M, Sponheim, Scott R, De Haan, Lieuwe, and Koenders, Laura

Subjects
Karolinska Schizophrenia Project, Brain, Frontal Lobe, Prefrontal Cortex, Temporal Lobe, Humans, Magnetic Resonance Imaging, Severity of Illness Index, Linear Models, Case-Control Studies, Schizophrenia, Age of Onset, Adolescent, Adult, Aged, Middle Aged, Child, Female, Male, Young Adult, Neuroimaging, Cortical, Imaging, Meta-analysis, Surface area, Thickness, Serious Mental Illness, Biomedical Imaging, Mental Health, Clinical Research, Neurosciences, Brain Disorders, Mental health, Biological Sciences, Medical and Health Sciences, Psychology and Cognitive Sciences, Psychiatry
Abstract

BackgroundThe profile of cortical neuroanatomical abnormalities in schizophrenia is not fully understood, despite hundreds of published structural brain imaging studies. This study presents the first meta-analysis of cortical thickness and surface area abnormalities in schizophrenia conducted by the ENIGMA (Enhancing Neuro Imaging Genetics through Meta Analysis) Schizophrenia Working Group.MethodsThe study included data from 4474 individuals with schizophrenia (mean age, 32.3 years; range, 11-78 years; 66% male) and 5098 healthy volunteers (mean age, 32.8 years; range, 10-87 years; 53% male) assessed with standardized methods at 39 centers worldwide.ResultsCompared with healthy volunteers, individuals with schizophrenia have widespread thinner cortex (left/right hemisphere: Cohen's d = -0.530/-0.516) and smaller surface area (left/right hemisphere: Cohen's d = -0.251/-0.254), with the largest effect sizes for both in frontal and temporal lobe regions. Regional group differences in cortical thickness remained significant when statistically controlling for global cortical thickness, suggesting regional specificity. In contrast, effects for cortical surface area appear global. Case-control, negative, cortical thickness effect sizes were two to three times larger in individuals receiving antipsychotic medication relative to unmedicated individuals. Negative correlations between age and bilateral temporal pole thickness were stronger in individuals with schizophrenia than in healthy volunteers. Regional cortical thickness showed significant negative correlations with normalized medication dose, symptom severity, and duration of illness and positive correlations with age at onset.ConclusionsThe findings indicate that the ENIGMA meta-analysis approach can achieve robust findings in clinical neuroscience studies; also, medication effects should be taken into account in future genetic association studies of cortical thickness in schizophrenia.

Published
2018

36. Disrupted network cross talk, hippocampal dysfunction and hallucinations in schizophrenia.

Author

Hare, Stephanie M, Law, Alicia S, Ford, Judith M, Mathalon, Daniel H, Ahmadi, Aral, Damaraju, Eswar, Bustillo, Juan, Belger, Aysenil, Lee, Hyo Jong, Mueller, Bryon A, Lim, Kelvin O, Brown, Gregory G, Preda, Adrian, van Erp, Theo GM, Potkin, Steven G, Calhoun, Vince D, and Turner, Jessica A

Subjects
Hippocampus, Neural Pathways, Humans, Hallucinations, Magnetic Resonance Imaging, Brain Mapping, Schizophrenia, Schizophrenic Psychology, Rest, Adult, Female, Male, ALFF, FNC, Resting-state, fMRI, Mental Health, Serious Mental Illness, Brain Disorders, Neurosciences, Clinical Research, Aetiology, 2.1 Biological and endogenous factors, Neurological, Mental health, Medical and Health Sciences, Psychology and Cognitive Sciences, Psychiatry
Abstract

Hallucinations characterize schizophrenia, with approximately 59% of patients reporting auditory hallucinations and 27% reporting visual hallucinations. Prior neuroimaging studies suggest that hallucinations are linked to disrupted communication across distributed (sensory, salience-monitoring and subcortical) networks. Yet, our understanding of the neurophysiological mechanisms that underlie auditory and visual hallucinations in schizophrenia remains limited. This study integrates two resting-state functional magnetic resonance imaging (fMRI) analysis methods - amplitudes of low-frequency fluctuations (ALFF) and functional network connectivity (FNC) - to explore the hypotheses that (1) abnormal FNC between salience and sensory (visual/auditory) networks underlies hallucinations in schizophrenia, and (2) disrupted hippocampal oscillations (as measured by hippocampal ALFF) beget changes in FNC linked to hallucinations. Our first hypothesis was supported by the finding that schizophrenia patients reporting hallucinations have higher FNC between the salience network and an associative auditory network relative to healthy controls. Hippocampal ALFF was negatively associated with FNC between primary auditory cortex and the salience network in healthy subjects, but was positively associated with FNC between these networks in patients reporting hallucinations. These findings provide indirect support favoring our second hypothesis. We suggest future studies integrate fMRI with electroencephalogram (EEG) and/or magnetoencephalogram (MEG) methods to directly probe the temporal relation between altered hippocampal oscillations and changes in cross-network functional communication.

Published
2018

39. Hitomi X-ray studies of Giant Radio Pulses from the Crab pulsar

Author

Hitomi Collaboration, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W., Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W., Blandford, Roger, Brenneman, Laura W., Brown, Gregory V., Bulbul, Esra, Cackett, Edward M., Chernyakova, Maria, Chiao, Meng P., Coppi, Paolo S., Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P., Herder, Jan-Willem den, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E., Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C., Ferrigno, Carlo, Foster, Adam R., Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C., Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M., Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S., Hornschemeier, Ann, Hoshino, Akio, Hughes, John P., Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L., Kilbourne, Caroline A., Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A., Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A., Limousin, Olivier O., Loewenstein, Michael, Long, Knox S., Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R., Mehdipour, Missagh, Miller, Eric D., Miller, Jon M., Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F., Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K., Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Oshimizu, Kenya, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S., Pottschmidt, Katja, Reynolds, Christopher S., Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J., Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K., Soong, Yang, Stawarz, Ł ukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shiníchiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T., Tashiro, Makoto S., Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shiníchiro, Urry, C. Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R., Williams, Brian J., Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y., Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, Zoghbi, Abderahmen, Terasawa, Toshio, Sekido, Mamoru, Takefuji, Kazuhiro, Kawai, Eiji, Misawa, Hiroaki, Tsuchiya, Fuminori, Yamazaki, Ryo, Kobayashi, Eiji, Kisaka, Shota, and Aoki, Takahiro

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

To search for giant X-ray pulses correlated with the giant radio pulses (GRPs) from the Crab pulsar, we performed a simultaneous observation of the Crab pulsar with the X-ray satellite Hitomi in the 2 -- 300 keV band and the Kashima NICT radio observatory in the 1.4 -- 1.7 GHz band with a net exposure of about 2 ks on 25 March 2016, just before the loss of the Hitomi mission.The timing performance of the Hitomi instruments was confirmed to meet the timing requirement and about 1,000 and 100 GRPs were simultaneously observed at the main and inter-pulse phases, respectively, and we found no apparent correlation between the giant radio pulses and the X-ray emission in either the main or inter-pulse phases.All variations are within the 2 sigma fluctuations of the X-ray fluxes at the pulse peaks, and the 3 sigma upper limits of variations of main- or inter- pulse GRPs are 22\% or 80\% of the peak flux in a 0.20 phase width, respectively, in the 2 -- 300 keV band.The values become 25\% or 110\% for main or inter-pulse GRPs, respectively, when the phase width is restricted into the 0.03 phase.Among the upper limits from the Hitomi satellite, those in the 4.5-10 keV and the 70-300 keV are obtained for the first time, and those in other bands are consistent with previous reports.Numerically, the upper limits of main- and inter-pulse GRPs in the 0.20 phase width are about (2.4 and 9.3) $\times 10^{-11}$ erg cm$^{-2}$, respectively. No significant variability in pulse profiles implies that the GRPs originated from a local place within the magnetosphere and the number of photon-emitting particles temporally increases.However, the results do not statistically rule out variations correlated with the GRPs, because the possible X-ray enhancement may appear due to a $>0.02$\% brightening of the pulse-peak flux under such conditions., Comment: 18 pages, 7 figure, 6 tables, accepted for publication in PASJ

Published
2017
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40. Phase diagrams and free-energy landscapes for model spin-crossover materials with antiferromagnetic-like nearest-neighbor and ferromagnetic-like long-range interactions

Author

Chan, Chor-Hoi, Brown, Gregory, and Rikvold, Per Arne

Subjects
Condensed Matter - Materials Science, Condensed Matter - Other Condensed Matter, Condensed Matter - Statistical Mechanics
Abstract

We present phase diagrams, free-energy landscapes, and order-parameter distributions for a model spin-crossover material with a two-step transition between the high-spin and low-spin states (a square-lattice Ising model with antiferromagnetic-like nearest-neighbor and ferromagnetic-like long-range interactions) [P. A. Rikvold et al., Phys. Rev. B 93, 064109 (2016)]. The results are obtained by a recently introduced, macroscopically constrained Wang-Landau Monte Carlo simulation method [C. H. Chan, G. Brown, and P. A. Rikvold, Phys. Rev. E 95, 053302 (2017)]. The method's computational efficiency enables calculation of thermodynamic quantities for a wide range of temperatures, applied fields, and long-range interaction strengths. For long-range interactions of intermediate strength, tricritical points in the phase diagrams are replaced by pairs of critical end points and mean-field critical points that give rise to horn-shaped regions of metastability. The corresponding free-energy landscapes offer insights into the nature of asymmetric, multiple hysteresis loops that have been experimentally observed in spin-crossover materials characterized by competing short-range interactions and long-range elastic interactions., Comment: 35 pages, 20 figures

Published
2017
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41. Density of states for systems with multiple order parameters: a constrained Wang-Landau method

Author

Chan, Chor-Hoi, Brown, Gregory, and Rikvold, Per Arne

Subjects
Condensed Matter - Statistical Mechanics, Physics - Computational Physics
Abstract

A macroscopically constrained Wang-Landau Monte Carlo method was recently proposed to calculate the joint density of states (DOS) for systems with multiple order parameters. Here we demonstrate results for a nearest-neighbor Ising antiferromagnet with ferromagnetic long-range interactions (a model spin-crossover material). Its two relevant order parameters are the magnetization $M$ and the staggered magnetization $M_{\rm s}$. The joint DOS, $g(E,M,M_{\rm s})$ where $E$ is the total system energy, is calculated for zero external field and long-range interaction strength, and then obtained for arbitrary values of these two field-like model parameters by a simple transformation of $E$. Illustrations are shown for several parameter sets., Comment: 8 pages, 3 figures

Published
2017
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42. Macroscopically constrained Wang-Landau method for systems with multiple order parameters and its application to drawing complex phase diagrams

Author

Chan, Chor-Hoi, Brown, Gregory, and Rikvold, Per Arne

Subjects
Condensed Matter - Statistical Mechanics, Physics - Computational Physics
Abstract

A generalized approach to Wang-Landau simulations, macroscopically constrained Wang-Landau, is proposed to simulate the density of states of a system with multiple macroscopic order parameters. The method breaks a multidimensional random-walk process in phase space into many separate, one-dimensional random-walk processes in well-defined subspaces. Each of these random walks is constrained to a different set of values of the macroscopic order parameters. When the multi-variable density of states is obtained for one set of values of field-like model parameters, the density of states for any other values of these parameters can be obtained by a simple transformation of the total system energy. All thermodynamic quantities of the system can then be rapidly calculated at any point in the phase diagram. We demonstrate how to use the multi-variable density of states to draw the phase diagram, as well as order-parameter probability distributions at specific phase points, for a model spin-crossover material: an antiferromagnetic Ising model with ferromagnetic long-range interactions. The field-like parameters in this model are an effective magnetic field and the strength of the long-range interaction., Comment: 35 pages, 11 figures

Published
2017
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43. Cutaneous shedding in amphibians causes shifts in bacterial microbiomes.

Author

WEITZMAN, Chava L., BROWN, Gregory P., GIBB, Karen, and CHRISTIAN, Keith

Abstract

Considerable research has focused on microbes on amphibian skin, as they act as the first line of defense against invading pathogens. This effort has generated substantial data on patterns across species, space, time, and ontogeny, alongside a growing list of beneficial antifungal symbionts. Though there is evidence of stability in amphibian skin microbial communities, there is also an indication that regular skin shedding reduces cultivable bacteria, with regrowth and recolonization in the period between sheds. This suggests that skin communities are in constant flux, and we lack an understanding of how the membership and structure of those communities are affected by shedding events. In this study, we conducted experiments on cane toads (Rhinella marina) to investigate the influence of shedding on skin microbiomes. We first used quantitative PCR to verify a positive correlation between bacterial loads and time in the days after shedding. We then resampled individuals over time to describe changes in community composition in the 38 h after shedding using amplicon sequencing. Similar to trends of bacterial loads, we found increases in alpha diversity over time after shedding, suggesting that shedding reduces bacterial diversity as it knocks down bacterial loads. During the 38‐h period, community structure became similar to pre‐shed communities in some individuals, but there was no consistent pattern in structural changes among individuals. In light of the amphibian chytridiomycosis pandemic, understanding how physiological events such as skin shedding affect beneficial bacteria and communities on amphibians would provide important insight into amphibian ecology. [ABSTRACT FROM AUTHOR]

Published
2024
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45. Mental health issues of children and youth encountered by police.

Author

Hoffman, Alicia M., Hoffman, Ronald E., Smith, Trevor F., Brown, Gregory P., and Hirdes, John P.

Subjects
POLICE intervention, MENTAL health of youth, CHILDREN, POLICE training, SELF-injurious behavior
Abstract

The purpose of this study was to identify major characteristics of children and youth with mental health problems who have contact with police officers and to determine which variables lead to the highest probability of police intervention and if there are differences between children and youth compared to adults. Two samples were taken from data obtained from the use of a new police brief mental health screener (interRAI BMHS) in a large southwestern Ontario city between April 2016 and April 2019: 619 cases under age 18 and 4,084 cases over age 18. Univariate and bivariate analysis revealed that all 23 variables on the BMHS were significantly associated with police intervention except for intoxication by drugs or alcohol, squalid home environment, and refusal to take prescribed medication. Variables with the highest odds of police intervention included hallucinations, diminished cognitive skills for daily decision-making, and family or others concerned for potential self-harm. Logistic regression analysis indicated that the variables most predictive of police intervention were hallucinations, lack of insight into their own mental health problems, violent ideation, violence to others, self-injurious attempt in the last 7 days, suicide plan, diminished cognitive skills for daily decision-making, and family or others concerned for self-harm. As to the differences between under and over age 18, adults had higher frequencies of intoxication, hallucinations, delusions, pressured speech, and abnormal thoughts, while under age 18 had slightly higher frequency of socially inappropriate/disruptive behaviour. Risk of harm variables were high in both groups; however, they were clearly higher in the under age 18 group, in particular self-injurious attempt in the last 7 days. The results of this study indicate that there are distinct differences between why police officers intervene with children and youth as opposed to adults which should be reflected in police training and intervention policy. [ABSTRACT FROM AUTHOR]

Published
2024
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46. Cerebral blood flow predicts differential neurotransmitter activity.

Author

Dukart, Juergen, Holiga, Štefan, Chatham, Christopher, Hawkins, Peter, Forsyth, Anna, McMillan, Rebecca, Myers, Jim, Lingford-Hughes, Anne R, Nutt, David J, Merlo-Pich, Emilio, Risterucci, Celine, Boak, Lauren, Umbricht, Daniel, Schobel, Scott, Liu, Thomas, Mehta, Mitul A, Zelaya, Fernando O, Williams, Steve C, Brown, Gregory, Paulus, Martin, Honey, Garry D, Muthukumaraswamy, Suresh, Hipp, Joerg, Bertolino, Alessandro, and Sambataro, Fabio

Subjects
Central Nervous System, Humans, Neurotransmitter Agents, Anesthetics, Dissociative, Antipsychotic Agents, Central Nervous System Stimulants, Antidepressive Agents, Second-Generation, Magnetic Resonance Imaging, Cerebrovascular Circulation, Adult, Female, Male, Young Adult, Healthy Volunteers, Neurophysiological Monitoring, Brain Disorders, Neurosciences, Neurological, Anesthetics, Dissociative, Antidepressive Agents, Second-Generation, Biochemistry and Cell Biology, Other Physical Sciences
Abstract

Application of metabolic magnetic resonance imaging measures such as cerebral blood flow in translational medicine is limited by the unknown link of observed alterations to specific neurophysiological processes. In particular, the sensitivity of cerebral blood flow to activity changes in specific neurotransmitter systems remains unclear. We address this question by probing cerebral blood flow in healthy volunteers using seven established drugs with known dopaminergic, serotonergic, glutamatergic and GABAergic mechanisms of action. We use a novel framework aimed at disentangling the observed effects to contribution from underlying neurotransmitter systems. We find for all evaluated compounds a reliable spatial link of respective cerebral blood flow changes with underlying neurotransmitter receptor densities corresponding to their primary mechanisms of action. The strength of these associations with receptor density is mediated by respective drug affinities. These findings suggest that cerebral blood flow is a sensitive brain-wide in-vivo assay of metabolic demands across a variety of neurotransmitter systems in humans.

Published
2018

47. Effects of HIV Infection, methamphetamine dependence and age on cortical thickness, area and volume

Author

MacDuffie, Katherine E, Brown, Gregory G, McKenna, Benjamin S, Liu, Thomas T, Meloy, MJ, Tawa, Brianna, Archibald, Sarah, Fennema-Notestine, Christine, Atkinson, J Hampton, Ellis, Ronald J, Letendre, Scott L, Hesselink, John R, Cherner, Mariana, Grant, Igor, and Group, TMARC

Subjects
Medical Microbiology, Biomedical and Clinical Sciences, Methamphetamine, Infectious Diseases, Clinical Research, HIV/AIDS, Substance Misuse, Sexually Transmitted Infections, Infection, Adult, Anti-Retroviral Agents, Cerebral Cortex, Female, Frontal Lobe, Gyrus Cinguli, HIV Infections, Humans, Magnetic Resonance Imaging, Male, Middle Aged, Young Adult, HIV infection, Methamphetamine dependence, Aging, Cortical thickness, Cortical area, Cortical volume, TMARC Group, Neurosciences, Biological psychology, Clinical and health psychology
Abstract

ObjectiveThis study examined the effects of HIV infection, methamphetamine dependence and their interaction on cortical thickness, area and volume, as well as the potential interactive effects on cortical morphometry of HIV and methamphetamine with age.MethodT1-weighted structural images were obtained on a 3.0T General Electric MR750 scanner. Freesurfer v5.3.0 was used to derive cortical thickness, area and volume measures in thirty-four regions based on Desikan-Killiany atlas labels.ResultsFollowing correction for multiple statistical tests, HIV diagnosis was not significantly related to cortical thickness or area in any ROI, although smaller global cortical area and volume were seen in those with lower nadir CD4 count. HIV diagnosis, nevertheless, was associated with smaller mean cortical volumes in rostral middle frontal gyrus and in the inferior and superior parietal lobes. Methamphetamine dependence was significantly associated with thinner cortex especially in posterior cingulate gyrus, but was not associated with cortical area or volume following correction for multiple statistical tests. We found little evidence that methamphetamine dependence moderated differences in cortical area, volume or thickness for any ROI in the HIV seropositive group. Interactions with age revealed that HIV diagnosis attenuated the degree of age-related cortical thinning seen in non-infected individuals; intercepts indicated that young HIV seropositive individuals had thinner cortex than non-infected peers.ConclusionsMethamphetamine dependence does not appear to potentiate a reduction of cortical area, volume or thickness in HIV seropositive individuals. The finding of thinner cortex in young HIV seropositive individuals and the association between CD4 nadir and global cortical area and volume argue for prioritizing early antiretroviral treatment.

Published
2018

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