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Full-Text Articles in Physical Sciences and Mathematics

Review Of: The World Of Scary Video Games: A Study In Videoludic Horror, Approaches To Digital Game Studies, Matthew Murray Dec 2018

Review Of: The World Of Scary Video Games: A Study In Videoludic Horror, Approaches To Digital Game Studies, Matthew Murray

Library Faculty Publications

No abstract provided.


Linking Gait Dynamics To Mechanical Cost Of Legged Locomotion, David V. Lee, Sarah L. Harris Oct 2018

Linking Gait Dynamics To Mechanical Cost Of Legged Locomotion, David V. Lee, Sarah L. Harris

Life Sciences Faculty Publications

For millenia, legged locomotion has been of central importance to humans for hunting, agriculture, transportation, sport, and warfare. Today, the same principal considerations of locomotor performance and economy apply to legged systems designed to serve, assist, or be worn by humans in urban and natural environments. Energy comes at a premium not only for animals, wherein suitably fast and economical gaits are selected through organic evolution, but also for legged robots that must carry sufficient energy in their batteries. Although a robot's energy is spent at many levels, from control systems to actuators, we suggest that the mechanical cost ...


Streaming Instability Of Multiple Particle Species In Protoplanetary Disks, Noemi Schaffer, Chao-Chin Yang, Anders Johansen Oct 2018

Streaming Instability Of Multiple Particle Species In Protoplanetary Disks, Noemi Schaffer, Chao-Chin Yang, Anders Johansen

Physics & Astronomy Faculty Publications

The radial drift and diffusion of dust particles in protoplanetary disks affect both the opacity and temperature of such disks, as well as the location and timing of planetesimal formation. In this paper, we present results of numerical simulations of particle-gas dynamics in protoplanetary disks that include dust grains with various size distributions. We have considered three scenarios in terms of particle size ranges, one where the Stokes number τs = 10−1−100, one where τs = 10−4−10−1, and finally one where τs= 10−3−100. Moreover, we considered both discrete and continuous distributions in particle size. In ...


A Bayesian Framework For Exoplanet Direct Detection And Non-Detection, Jean-Baptiste Ruffio, Dimitri Mawet, Ian Czekala, Bruce Macintosh, Robert J. De Rosa, Garreth Ruane, Michael Bottom, Laurent Pueyo, Jason J. Wang, Lea Hirsch, Zhaohuan Zhu, Eric L. Nielsen Oct 2018

A Bayesian Framework For Exoplanet Direct Detection And Non-Detection, Jean-Baptiste Ruffio, Dimitri Mawet, Ian Czekala, Bruce Macintosh, Robert J. De Rosa, Garreth Ruane, Michael Bottom, Laurent Pueyo, Jason J. Wang, Lea Hirsch, Zhaohuan Zhu, Eric L. Nielsen

Physics & Astronomy Faculty Publications

Rigorously quantifying the information in high-contrast imaging data is important for informing follow-up strategies to confirm the substellar nature of a point source, constraining theoretical models of planet–disk interactions, and deriving planet occurrence rates. However, within the exoplanet direct imaging community, non-detections have almost exclusively been defined using a frequentist detection threshold (i.e., contrast curve) and associated completeness. This can lead to conceptual inconsistencies when included in a Bayesian framework. A Bayesian upper limit is such that the true value of a parameter lies below this limit with a certain probability. The associated probability is the integral of ...


Reaction Optimization Of Pyrazinoquinoxaline Based Organic Semiconductor With Cruciform Shape, Marco Valverde Paredes, Dong-Chan Lee Oct 2018

Reaction Optimization Of Pyrazinoquinoxaline Based Organic Semiconductor With Cruciform Shape, Marco Valverde Paredes, Dong-Chan Lee

LSAMP Poster Presentations

In this work, an optimum reaction condition was established to synthesize a pyrazinoquinoxaline based organic semiconductor with cruciform shape.


Multicolor Blackbody Emission In Grb 081221, Shu-Jin Hou, Bin-Bin Zhang, Yan-Zhi Meng, Xue-Feng Wu, En-Wei Liang, Hou-Jun Lü, Tong Liu, Yun-Feng Liang, Lin Lin, Rui-Jing Lu, Jin-Shu Huang, Bing Zhang Oct 2018

Multicolor Blackbody Emission In Grb 081221, Shu-Jin Hou, Bin-Bin Zhang, Yan-Zhi Meng, Xue-Feng Wu, En-Wei Liang, Hou-Jun Lü, Tong Liu, Yun-Feng Liang, Lin Lin, Rui-Jing Lu, Jin-Shu Huang, Bing Zhang

Physics & Astronomy Faculty Publications

The radiation mechanism of the prompt emission of gamma-ray bursts (GRBs) remains an open question. Although their spectra are usually well fitted with the empirical Band function, which is widely believed to be fully nonthermal and interpreted as an optically thin synchrotron emission, accumulating evidence shows that a thermal component actually exists. In this paper, a multicolor blackbody (mBB) model is proposed for the time-integrated spectrum of GRB 081221 by assuming a power-law distribution of the thermal luminosities with temperature, which manifests photospheric emissions from a different radius and/or angle. The effects of the minimum temperature kT min, the ...


A Comprehensive Analysis Of Fermi Gamma-Ray Burst Data. Iv. Spectral Lag And Its Relation To E P Evolution, Rui-Jing Lu, Yun-Feng Liang, Da-Bin Lin, Jing Lü, Xiang-Gao Wang, Hou-Jun Lü, Hong-Bang Liu, En-Wei Liang, Bing Zhang Oct 2018

A Comprehensive Analysis Of Fermi Gamma-Ray Burst Data. Iv. Spectral Lag And Its Relation To E P Evolution, Rui-Jing Lu, Yun-Feng Liang, Da-Bin Lin, Jing Lü, Xiang-Gao Wang, Hou-Jun Lü, Hong-Bang Liu, En-Wei Liang, Bing Zhang

Physics & Astronomy Faculty Publications

The spectral evolution and spectral lag behavior of 92 bright pulses from 84 gamma-ray bursts observed by the Fermi Gamma-ray Burst Monitor (GBM) telescope are studied. These pulses can be classified into hard-to-soft pulses (H2S; 64/92), H2S-dominated-tracking pulses (21/92), and other tracking pulses (7/92). We focus on the relationship between spectral evolution and spectral lags of H2S and H2S-dominated-tracking pulses. The main trend of spectral evolution (lag behavior) is estimated with ( ), where E p is the peak photon energy in the radiation spectrum, t + t 0 is the observer time relative to the beginning of pulse −t ...


Pressure Effect On The Antiferromagnetic Compound Ce2ni3ge5, Jun Gouchi, Yuki Nakamura, Miho Nakashima, Tasushi Amako, Ravhi Kumar, Yoshiya Uwatoko Oct 2018

Pressure Effect On The Antiferromagnetic Compound Ce2ni3ge5, Jun Gouchi, Yuki Nakamura, Miho Nakashima, Tasushi Amako, Ravhi Kumar, Yoshiya Uwatoko

Physics & Astronomy Faculty Publications

In this study, the electrical resistivity and magnetization of a single crystal of Ce2Ni3Ge5 heavy fermion compound were performed under pressure. The resistivity and magnetization showed two antiferromagnetic transitions at ambient pressure. On applying pressure, the transitions merged at 1 GPa. At higher pressures, the antiferromagnetic transition temperature decreases, and disappears. It is suggesting that the critical pressure of Ce2Ni3Ge5 was 4.1 GPa.


Review Of: Families At Play: Connecting And Learning Through Video Games, Matthew Murray Oct 2018

Review Of: Families At Play: Connecting And Learning Through Video Games, Matthew Murray

Library Faculty Publications

No abstract provided.


The Optical/Nir Afterglow Of Grb 111209a: Complex Yet Not Unprecedented, D. A. Kann, P. Schady, E. F. Olivares, S. Klose, A. Rossi, D. A. Perley, Bing Zhang, T. Krühler, J. Greiner, A. Nicuesa Guelbenzu, J. Elliott, F. Knust, Z. Cano, R. Filgas, E. Pian, P. Mazzali, J. P. U. Fynbo, G. Leloudas, P. M. J. Afonso, C. Delvaux, J. F. Graham, A. Rau, S. Schmidl, S. Schulze, M. Tanga, A. C. Updike, K. Varela Oct 2018

The Optical/Nir Afterglow Of Grb 111209a: Complex Yet Not Unprecedented, D. A. Kann, P. Schady, E. F. Olivares, S. Klose, A. Rossi, D. A. Perley, Bing Zhang, T. Krühler, J. Greiner, A. Nicuesa Guelbenzu, J. Elliott, F. Knust, Z. Cano, R. Filgas, E. Pian, P. Mazzali, J. P. U. Fynbo, G. Leloudas, P. M. J. Afonso, C. Delvaux, J. F. Graham, A. Rau, S. Schmidl, S. Schulze, M. Tanga, A. C. Updike, K. Varela

Physics & Astronomy Faculty Publications

Context. Afterglows of gamma-ray bursts (GRBs) are simple in the most basic model, but can show many complex features. The ultra-long duration GRB 111209A, one of the longest GRBs ever detected, also has the best-monitored afterglow in this rare class of GRBs. Aims. We want to address the question whether GRB 111209A was a special event beyond its extreme duration alone, and whether it is a classical GRB or another kind of high-energy transient. The afterglow may yield significant clues. Methods. We present afterglow photometry obtained in seven bands with the GROND imager as well as in further seven bands ...


Strongly Lensed Repeating Fast Radio Bursts As Precision Probes Of The Universe, Zheng-Xiang Li, He Gao, Xu-Heng Ding, Guo-Jian Wang, Bing Zhang Sep 2018

Strongly Lensed Repeating Fast Radio Bursts As Precision Probes Of The Universe, Zheng-Xiang Li, He Gao, Xu-Heng Ding, Guo-Jian Wang, Bing Zhang

Physics & Astronomy Faculty Publications

See full text for abstract.


Computational Discovery Of A New Rhombohedral Diamond Phase, Zhen-Zhen Li, Jian-Tao Wang, Hiroshi Mizuseki, Changfeng Chen Sep 2018

Computational Discovery Of A New Rhombohedral Diamond Phase, Zhen-Zhen Li, Jian-Tao Wang, Hiroshi Mizuseki, Changfeng Chen

Physics & Astronomy Faculty Publications

We identify by first-principles calculations a new diamond phase in R¯3c (D63d) symmetry, which has a 16-atom rhombohedral primitive cell, thus termed R16 carbon. This rhombohedral diamond comprises a characteristic all-sp3 six-membered-ring bonding network, and it is energetically more stable than previously identified diamondlike six-membered-ring bonded BC8 and BC12 carbon phases. A phonon mode analysis verifies the dynamic structural stability of R16 carbon, and electronic band calculations reveal that it is an insulator with a direct band gap of 4.45 eV. Simulated x-ray diffraction patterns provide an excellent match to recently reported distinct diffraction peaks found in milled ...


The Sisal Database: A Global Resource To Document Oxygen And Carbon Isotope Records From Speleothems, Kamolphat Atsawawaranunt, Laia Comas-Bru, Sahar Amirnezhad Mozhdehi, Michael Deininger, Sandy P. Harrison, Andy Baker, Meighan Boyd, Nikita Kaushal, Syed Masood Ahmad, Yassine Ait Brahim, Monica Arienzo, Petra Bajo, Kerstin Braun, Yuval Burstyn, Sakonvan Chawchai, Wuhui Duan, István Gábor Hatvani, Jun Hu, Zoltán Kern, Inga Labuhn, Matthew Lachniet, Franziska A. Lechleitner, Andrew Lorrey, Carlos Pérez-Mejías, Robyn Pickering, Nick Scroxton, Sisal Working Group Members Sep 2018

The Sisal Database: A Global Resource To Document Oxygen And Carbon Isotope Records From Speleothems, Kamolphat Atsawawaranunt, Laia Comas-Bru, Sahar Amirnezhad Mozhdehi, Michael Deininger, Sandy P. Harrison, Andy Baker, Meighan Boyd, Nikita Kaushal, Syed Masood Ahmad, Yassine Ait Brahim, Monica Arienzo, Petra Bajo, Kerstin Braun, Yuval Burstyn, Sakonvan Chawchai, Wuhui Duan, István Gábor Hatvani, Jun Hu, Zoltán Kern, Inga Labuhn, Matthew Lachniet, Franziska A. Lechleitner, Andrew Lorrey, Carlos Pérez-Mejías, Robyn Pickering, Nick Scroxton, Sisal Working Group Members

Geoscience Faculty Publications

Stable isotope records from speleothems provide information on past climate changes, most particularly information that can be used to reconstruct past changes in precipitation and atmospheric circulation. These records are increasingly being used to provide out-of-sample evaluations of isotope-enabled climate models. SISAL (Speleothem Isotope Synthesis and Analysis) is an international working group of the Past Global Changes (PAGES) project. The working group aims to provide a comprehensive compilation of speleothem isotope records for climate reconstruction and model evaluation. The SISAL database contains data for individual speleothems, grouped by cave system. Stable isotopes of oxygen and carbon (δ18O, δ13C) measurements are ...


Long-Lived Remnants From Binary Neutron Star Mergers, David Radice, Albino Perego, Sebastiano Bernuzzi, Bing Zhang Sep 2018

Long-Lived Remnants From Binary Neutron Star Mergers, David Radice, Albino Perego, Sebastiano Bernuzzi, Bing Zhang

Physics & Astronomy Faculty Publications

Massive neutron stars (NSs) with lifetimes of at least several seconds are expected to be the result of a sizable fraction of NS mergers. We study their formation using a large set of numerical relativity simulations. We show that they are initially endowed with angular momentum that significantly exceeds the mass-shedding limit for rigidly rotating equilibria. We find that gravitational wave (GW) emission is not able to remove this excess angular momentum within the time over which solid body rotation should be achieved. Instead, we argue that the excess angular momentum could be carried away by massive winds. Long-lived merger ...


Unraveling The Stereodynamics Of Cold Controlled Hd−H2 Collisions, James F. E. Croft, Naduvalath Balakrishnan, Meng Huang, Hua Guo Sep 2018

Unraveling The Stereodynamics Of Cold Controlled Hd−H2 Collisions, James F. E. Croft, Naduvalath Balakrishnan, Meng Huang, Hua Guo

Chemistry and Biochemistry Faculty Publications

Measuring inelastic rates with partial-wave resolution requires temperatures close to a Kelvin or below, even for the lightest molecule. In a recent experiment, Perreault, Mukherjee, and Zare [Nat. Chem. 10, 561 (2018).] studied collisional relaxation of excited HD molecules in the v=1, j=2 state by para- and ortho-H2 at a temperature of about 1 K, extracting the angular distribution of scattered HD in the v=1, j=0 state. By state preparation of the HD molecules, control of the angular distribution of scattered HD was demonstrated. Here, we report a first-principles simulation of that experiment which enables us ...


Parametric Study Of The Rossby Wave Instability In A Two-Dimensional Barotropic Disk. Ii. Nonlinear Calculations, Tomohiro Ono, Takayuki Muto, Kengo Tomida, Zhaohuan Zhu Aug 2018

Parametric Study Of The Rossby Wave Instability In A Two-Dimensional Barotropic Disk. Ii. Nonlinear Calculations, Tomohiro Ono, Takayuki Muto, Kengo Tomida, Zhaohuan Zhu

Physics & Astronomy Faculty Publications

Vortices in protoplanetary disks have attracted attention since the discovery of lopsided structures. One of the possible mechanisms for producing vortices is the Rossby wave instability (RWI). In our previous work, we have performed detailed linear stability analyses of the RWI with various initial conditions. In this paper, we perform numerical simulations of the vortex formation by the RWI in two-dimensional barotropic disks using the Athena++ code. As initial conditions, we consider axisymmetric disks with a Gaussian surface density bump of various contrasts and half-widths. Perturbations grow as expected from the linear stability analyses in the linear and weakly nonlinear ...


Understanding The Death Of Massive Stars Using An Astrophysical Transients Observatory, Peter W. Roming, Eddie Baron, Amanda J. Bayless, Volker Bromm, Peter J. Brown, Michael W. Davis, Anastasia Fialkov, Brian Fleming, Kevin France, Chris L. Fryer, Thomas K. Greathouse, Jed J. Hancock, D. Andrew Howell, Andrew J. Levan, Abraham Loeb, Raffaella Margutti, Mark L. Mcconnell, Paul T. O'Brien, Julian P. Osborne, Daniel A. Perley, Eric M. Schlegel, Rhaana L. C. Starling, Nial R. Tanvir, Mark Tapley, Patrick A. Young, Bing Zhang Aug 2018

Understanding The Death Of Massive Stars Using An Astrophysical Transients Observatory, Peter W. Roming, Eddie Baron, Amanda J. Bayless, Volker Bromm, Peter J. Brown, Michael W. Davis, Anastasia Fialkov, Brian Fleming, Kevin France, Chris L. Fryer, Thomas K. Greathouse, Jed J. Hancock, D. Andrew Howell, Andrew J. Levan, Abraham Loeb, Raffaella Margutti, Mark L. Mcconnell, Paul T. O'Brien, Julian P. Osborne, Daniel A. Perley, Eric M. Schlegel, Rhaana L. C. Starling, Nial R. Tanvir, Mark Tapley, Patrick A. Young, Bing Zhang

Physics & Astronomy Faculty Publications

The death of massive stars, manifested as gamma-ray bursts and core-collapse supernovae, critically influence how the universe formed and evolves. Despite their fundamental importance, our understanding of these enigmatic objects is severely limited. We have performed a concept study of an Astrophysical Transient Observatory (ATO) that will rapidly facilitate an expansion of our understanding of these objects. ATO combines a very wide-field X-ray telescope, a near-infrared telescope, a multi-mode ultraviolet instrument, and a rapidly slewing spacecraft to realize two primary goals: (1) characterize the highest-redshift massive stars and their environments, and (2) constrain the poorly understood explosion mechanism of massive ...


Synchrotron Radiation From Electrons With A Pitch-Angle Distribution, Yuan-Pei Yang, Bing Zhang Aug 2018

Synchrotron Radiation From Electrons With A Pitch-Angle Distribution, Yuan-Pei Yang, Bing Zhang

Physics & Astronomy Faculty Publications

In most astrophysical processes involving synchrotron radiation, the pitch-angle distribution of the electrons is assumed to be isotropic. However, if electrons are accelerated anisotropically, e.g., in a relativistic shock wave with an ordered magnetic field or in magnetic reconnection regions, the electron pitch angles might be anisotropic. In this Letter, we study synchrotron radiation from electrons with a pitch-angle distribution with respect to a large-scale uniform magnetic field. Assuming that the pitch-angle distribution is normal with a scatter of σ p and that the viewing direction is where the pitch-angle direction peaks, we find that for electrons with a ...


Multiferroic And Ferroic Topological Order In Ligand-Functionalized Germanene And Arsenene, Liangzhi Kou, Yandong Ma, Ting Liao, Aijun Du, Changfeng Chen Aug 2018

Multiferroic And Ferroic Topological Order In Ligand-Functionalized Germanene And Arsenene, Liangzhi Kou, Yandong Ma, Ting Liao, Aijun Du, Changfeng Chen

Physics & Astronomy Faculty Publications

Two-dimensional (2D) materials that exhibit ferroelectric, ferromagnetic, or topological order have been a major focal topic of nanomaterials research in recent years. The latest efforts in this field explore 2D quantum materials that host multiferroic or concurrent ferroic and topological order. We present a computational discovery of multiferroic state with coexisting ferroelectric and ferromagnetic order in recently synthesized CH2OCH3-functionalized germanene. We show that an electric-field-induced rotation of the ligand CH2OCH3 molecule can serve as the driving mechanism to switch the electric polarization of the ligand molecule, while unpassivated Ge p(z) orbits generate ferromagnetism. Our study also reveals coexisting ferroelectric ...


Warping A Protoplanetary Disc With A Planet On An Inclined Orbit, Rebecca Nealon, Giovanni Dipierro, Richard Alexander, Rebecca G. Martin, Chris Nixon Aug 2018

Warping A Protoplanetary Disc With A Planet On An Inclined Orbit, Rebecca Nealon, Giovanni Dipierro, Richard Alexander, Rebecca G. Martin, Chris Nixon

Physics & Astronomy Faculty Publications

Recent observations of several protoplanetary discs have found evidence of departures from flat, circular motion in the inner regions of the disc. One possible explanation for these observations is a disc warp, which could be induced by a planet on a misaligned orbit. We present three-dimensional numerical simulations of the tidal interaction between a protoplanetary disc and a misaligned planet. For low planet masses, we show that our simulations accurately model the evolution of inclined planet orbit (up to moderate inclinations). For a planet massive enough to carve a gap, the disc is separated into two components and the gas ...


Ttv-Determined Masses For Warm Jupiters And Their Close Planetary Companions, Dong-Hong Wu, Songhu Wang, Ji-Lin Zhou, Jason H. Steffen, Gregory Laughlin Aug 2018

Ttv-Determined Masses For Warm Jupiters And Their Close Planetary Companions, Dong-Hong Wu, Songhu Wang, Ji-Lin Zhou, Jason H. Steffen, Gregory Laughlin

Physics & Astronomy Faculty Publications

Although the formation and the properties of hot Jupiters (with orbital periods P < 10 days) have attracted a great deal of attention, the origins of warm Jupiters (10 < P < 100 days) are less well studied. Using a transit timing analysis, we present the orbital parameters of five planetary systems containing warm Jupiters, Kepler 30, Kepler 117, Kepler 302, Kepler 487, and Kepler 418. Three of them, Kepler-30 c(M p = 549.4 ± 5.6 M ⊕), Kepler-117 c(M p = 702 ± 63 M ⊕), and Kepler 302 c(M p = 933 ± 527 M ⊕), are confirmed to be real warm Jupiters based on their mass. Insights drawn from the radius–temperature relationship lead to the inference that hot Jupiters and warm Jupiters can be roughly separated by T eff,c = 1123.7 ± 3.3 K. Also, T eff,c provides a good separation for Jupiters with companion fraction consistent with zero (T eff > T eff,c) and those with companion fraction significantly different from zero (T eff < T eff,c).


Circumbinary Discs Around Merging Stellar-Mass Black Holes, Rebecca G. Martin, Chris Nixon, Fu-Guo Xie, Andrew King Aug 2018

Circumbinary Discs Around Merging Stellar-Mass Black Holes, Rebecca G. Martin, Chris Nixon, Fu-Guo Xie, Andrew King

Physics & Astronomy Faculty Publications

A circumbinary disc around a pair of merging stellar-mass black holes may be shocked and heated during the recoil of the merged hole, causing a near-simultaneous electromagnetic counterpart to the gravitational wave event. The shocks occur around the recoil radius, where the disc orbital velocity is equal to the recoil velocity. The amount of mass present near this radius at the time of the merger is critical in determining how much radiation is released. We explore the evolution of a circumbinary disc in two limits. First, we consider an accretion disc that feels no torque from the binary. The disc ...


Unraveling The Structure And Bonding Evolution Of The Newly Discovered Iron Oxide Feo2, Cheng Lu, Maximilian Amsler, Changfeng Chen Aug 2018

Unraveling The Structure And Bonding Evolution Of The Newly Discovered Iron Oxide Feo2, Cheng Lu, Maximilian Amsler, Changfeng Chen

Physics & Astronomy Faculty Publications

Recently reported synthesis of FeO2 at high pressure has stimulated great interest in exploring this new iron oxide and elucidating its properties. Here, we present a systematic computational study of crystal structure, chemical bonding, and sound velocity of FeO2 in a wide range of pressure. Our results establish thermodynamic stability of the experimentally observed pyrite phase (P-phase) of FeO2 at pressures above 74 GPa and unveil two metastable FeO2 phases in Pbcn and P4(2)/mnm symmetry at lower pressures. Simulated x-ray diffraction (XRD) spectra of Pbcn and P4(2)/mnm FeO2 match well with measured XRD data of the ...


Ultrafast Laser Filament-Induced Fluorescence Spectroscopy Of Uranyl Fluoride, P. J. Skrodzki, M. Burger, L. A. Finney, F. Poineau, S. M. Balasekaran, J. Nees, K. R. Czerwinski, I. Jovanovic Aug 2018

Ultrafast Laser Filament-Induced Fluorescence Spectroscopy Of Uranyl Fluoride, P. J. Skrodzki, M. Burger, L. A. Finney, F. Poineau, S. M. Balasekaran, J. Nees, K. R. Czerwinski, I. Jovanovic

Chemistry and Biochemistry Faculty Publications

Uranyl fluoride (UO2F2) is a compound which forms in the reaction between water and uranium hexafluoride, a uranium containing gas widely used for uranium enrichment. Uranyl fluoride exhibits negligible natural background in atmosphere; as a result, its observation implies the presence and active operation of nearby enrichment facilities and could be used as a tracer for treaty verification technologies. Additionally, detection of UO2F2 has a potential application in guiding remediation efforts around enrichment facilities. Laser-induced fluorescence (LIF) has been proposed in the past as a viable technique for the detection and tracking of UO2F2. We demonstrate that ultrafast laser filamentation ...


Characteristics Of Two-Episode Emission Patterns In Fermi Long Gamma-Ray Bursts, Lin Lan, Hou-Jun Lü, Shu-Qing Zhong, Hai-Ming Zhang, Jared Rice, Ji-Gui Cheng, Shen-Shi Du, Long Li, Jie Lin, Rui-Jing Lu, En-Wei Liang Aug 2018

Characteristics Of Two-Episode Emission Patterns In Fermi Long Gamma-Ray Bursts, Lin Lan, Hou-Jun Lü, Shu-Qing Zhong, Hai-Ming Zhang, Jared Rice, Ji-Gui Cheng, Shen-Shi Du, Long Li, Jie Lin, Rui-Jing Lu, En-Wei Liang

Physics & Astronomy Faculty Publications

Two-episode emission components separated by quiescent gaps in the prompt emission of gamma-ray bursts (GRBs) have been observed in the Swift era, but there is a lack of spectral information due to the narrow energy band of the Swift/Burst Alert Telescope. In this paper, a systematic analysis of the spectral and temporal properties of the prompt emission of 101 Fermi/Gamma-ray Burst Monitor detected long GRBs show the existence of two-episode emission components in the light curves, with quiescent times of up to hundreds of seconds. We focus on investigating the differences of those two emission episodes. We find ...


Gamma-Ray Burst/Supernova Associations: Energy Partition And The Case Of A Magnetar Central Engine, Hon-Jun Lü, Lin Lan, Bing Zhang, En-Wei Liang, David Alexander Kann, Shen-Shi Du, Jun Shen Jul 2018

Gamma-Ray Burst/Supernova Associations: Energy Partition And The Case Of A Magnetar Central Engine, Hon-Jun Lü, Lin Lan, Bing Zhang, En-Wei Liang, David Alexander Kann, Shen-Shi Du, Jun Shen

Physics & Astronomy Faculty Publications

The favored progenitor model for Gamma-ray Bursts (GRBs) with Supernova (SN) association is the core collapse of massive stars. One possible outcome of such a collapse is a rapidly spinning, strongly magnetized neutron star ("magnetar"). We systematically analyze the multi-wavelength data of GRB/SN associations detected by several instruments before 2017 June. Twenty GRB/SN systems have been confirmed via direct spectroscopic evidence or a clear light curve bump, as well as some spectroscopic evidence resembling a GRB-SN. We derive/collect the basic physical parameters of the GRBs and the SNe, and look for correlations among these parameters. We find ...


Collisional Quenching Of Highly Excited H2 Due To H2 Collisions, Yier Wan, B. H. Yang, P. C. Stancil, Balakrishnan Naduvalath, Nikhil J. Parekh, R. C. Forrey Jul 2018

Collisional Quenching Of Highly Excited H2 Due To H2 Collisions, Yier Wan, B. H. Yang, P. C. Stancil, Balakrishnan Naduvalath, Nikhil J. Parekh, R. C. Forrey

Chemistry and Biochemistry Faculty Publications

Rate coefficients for pure rotational quenching in H2(ν 1 = 0, j 1) + H2(ν 2 = 0, j 2) collisions from initial levels of j 1 = 2–31 (j 2 = 0 or 1) to all lower rotational levels are presented. We carried out extensive quantum mechanical close-coupling calculations based on a recently published H2–H2 potential energy surface (PES) developed by Patkowski et al. that has been demonstrated to be more reliable than previous work. Rotational transition cross sections with initial levels of j 1 = 2–14, 18, 19, 24, and 25 were computed for energies ranging from 10−6 ...


Mining Association Rules For Low-Frequency Itemsets, Jimmy Ming-Tai Wu, Justin Zhan, Sanket Chobe Jul 2018

Mining Association Rules For Low-Frequency Itemsets, Jimmy Ming-Tai Wu, Justin Zhan, Sanket Chobe

Computer Science Faculty Publications

High utility itemset mining has become an important and critical operation in the Data Mining field. High utility itemset mining generates more profitable itemsets and the association among these itemsets, to make business decisions and strategies. Although, high utility is important, it is not the sole measure to decide efficient business strategies such as discount offers. It is very important to consider the pattern of itemsets based on the frequency as well as utility to predict more profitable itemsets. For example, in a supermarket or restaurant, beverages like champagne or wine might generate high utility (profit), but also sell less ...


White Dwarf Pollution By Asteroids From Secular Resonances, Jeremy L. Smallwood, Rebecca G. Martin, Mario Livio, Stephen H. Lubow Jul 2018

White Dwarf Pollution By Asteroids From Secular Resonances, Jeremy L. Smallwood, Rebecca G. Martin, Mario Livio, Stephen H. Lubow

Physics & Astronomy Faculty Publications

In the past few decades, observations have revealed signatures of metals polluting the atmospheres of white dwarfs. The diffusion time-scale for metals to sink from the atmosphere of a white dwarf is of the order of days for a hydrogen-dominated atmosphere. Thus, there must be a continuous supply of metal-rich material accreting onto these white dwarfs. We investigate the role of secular resonances that excite the eccentricity of asteroids allowing them to reach star-grazing orbits leading them to tidal disruption and the formation of a debris disc. Changes in the planetary system during the evolution of the star lead to ...


What Powered The Optical Transient At2017gfo Associated With Gw170817?, Shao-Ze Li, Liang-Duan Liu, Yun-Wei Yu, Bing Zhang Jul 2018

What Powered The Optical Transient At2017gfo Associated With Gw170817?, Shao-Ze Li, Liang-Duan Liu, Yun-Wei Yu, Bing Zhang

Physics & Astronomy Faculty Publications

The groundbreaking discovery of the optical transient AT2017gfo associated with GW170817 opens a unique opportunity to study the physics of double neutron star (NS) mergers. We argue that the standard interpretation of AT2017gfo as being powered by radioactive decay of r-process elements faces the challenge of simultaneously accounting for the peak luminosity and peak time of the event, as it is not easy to achieve the required high mass, and especially the low opacity of the ejecta required to fit the data. A plausible solution would be to invoke an additional energy source, which is probably provided by the merger ...