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2019

University of Nevada, Las Vegas

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Articles 31 - 60 of 182

Full-Text Articles in Physical Sciences and Mathematics

Morphological Signatures Induced By Dust Back Reactions In Discs With An Embedded Planet, Chao-Chin Yang, Zhaohuan Zhu Nov 2019

Morphological Signatures Induced By Dust Back Reactions In Discs With An Embedded Planet, Chao-Chin Yang, Zhaohuan Zhu

Physics & Astronomy Faculty Research

Recent observations have revealed a gallery of substructures in the dust component of nearby protoplanetary discs, including rings, gaps, spiral arms, and lopsided concentrations. One interpretation of these substructures is the existence of embedded planets. Not until recently, however, most of the modelling effort to interpret these observations ignored the dust back reaction to the gas. In this work, we conduct local-shearing-sheet simulations for an isothermal, inviscid, non-self-gravitating, razor-thin dusty disc with a planet on a fixed circular orbit. We systematically examine the parameter space spanned by planet mass (0.1Mth ≤ Mp ≤ 1Mth, where Mth is the thermal mass), …

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Synthesis, Optical, And Thermal Properties Of 2,4,6-Tris(4-Substituted Phenyl)Pyrylium Tosylates And Triflimides, Pradip Kumar Bhowmik, Christina Inbok Lee, Jung Jae Koh, Haesook Han, Ahamed Jubair, Vladimir Kartazaev, Swapan Kumar Gayen Nov 2019

Synthesis, Optical, And Thermal Properties Of 2,4,6-Tris(4-Substituted Phenyl)Pyrylium Tosylates And Triflimides, Pradip Kumar Bhowmik, Christina Inbok Lee, Jung Jae Koh, Haesook Han, Ahamed Jubair, Vladimir Kartazaev, Swapan Kumar Gayen

Chemistry and Biochemistry Faculty Research

A group of five 2,4,6-tris(4-substituted phenyl)pyrylium tosylates were synthesized in one-pot reaction from para-substituted benzaldehyde and para-substituted acetophenones using tosic acid as a condensing agent. The tosylate salts were converted to the corresponding triflimide salts by metathesis reactions. Chemical structures, as well as optical spectroscopic and thermal properties of these salts were studied using pertinent experimental techniques. Trimethyl- and trihalo-substituted pyrylium salts emitted strong blue light with peaks in the 456 nm–479 nm range and trimethoxy-pyrylium salts emitted intense green light with maxima around 526 nm in acetonitrile solution. Quantum yields of the solutions were rather low, but the salts …

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Bis(Tetra­Phenyl­Arsonium) Hexa­Fluorido­Technetate(Iv) Dihydrate: Preparation, Structure And Spectroscopic Analysis, Samundeeswari Mariappan Balasekaran, Frederic Poineau Nov 2019

Bis(Tetra­Phenyl­Arsonium) Hexa­Fluorido­Technetate(Iv) Dihydrate: Preparation, Structure And Spectroscopic Analysis, Samundeeswari Mariappan Balasekaran, Frederic Poineau

Chemistry and Biochemistry Faculty Research

Reports of quadrivalent transition-metal fluoride salts containing bulky organic cations are limited. In this context, we prepared the bis­(tetra­phenyl­arsonium) hexa­fluorido­technetate(IV) dihydrate salt, (C24H20As)2[TcF6]·2H2O, by a cation metathesis reaction of (NH4)2[TcF6] in water. This is the first report of an arsonium salt of the hexa­fluorido­technetate(IV) dianion. (AsPh4)2[TcF6]·2H2O crystallizes in the triclinic space group P[\overline{1}]. The [TcF6]2− anion adopts a slightly distorted octa­hedral geometry with an average Tc—F bond length of 1.933 Å. The cyclic voltammogram of (AsPh4)2[TcF6]·2H2O in CH3CN shows a one-electron reversible oxidation wave at 1.496 V.

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Smooth Flow In Diamond: Atomistic Ductility And Electronic Conductivity, Chang Liu, Xianqi Song, Quan Li, Yanming Ma, Changfeng Chen Nov 2019

Smooth Flow In Diamond: Atomistic Ductility And Electronic Conductivity, Chang Liu, Xianqi Song, Quan Li, Yanming Ma, Changfeng Chen

Physics & Astronomy Faculty Research

Diamond is the quintessential superhard material widely known for its stiff and brittle nature and large electronic band gap. In stark contrast to these established benchmarks, our first-principles studies unveil surprising intrinsic structural ductility and electronic conductivity in diamond under coexisting large shear and compressive strains. These complex loading conditions impede brittle fracture modes and promote atomistic ductility, triggering rare smooth plastic flow in the normally rigid diamond crystal. This extraordinary structural change induces a concomitant band gap closure, enabling smooth charge flow in deformation created conducting channels. These startling soft-and-conducting modes reveal unprecedented fundamental characteristics of diamond, with profound …

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Design And Modeling Of A New Biomimetic Soft Robotic Jellyfish Using Ipmc-Based Electroactive Polymers, Zakai J. Olsen, Kwang J. Kim Nov 2019

Design And Modeling Of A New Biomimetic Soft Robotic Jellyfish Using Ipmc-Based Electroactive Polymers, Zakai J. Olsen, Kwang J. Kim

Mechanical Engineering Faculty Research

Smart materials and soft robotics have been seen to be particularly well-suited for developing biomimetic devices and are active fields of research. In this study, the design and modeling of a new biomimetic soft robot is described. Initial work was made in the modeling of a biomimetic robot based on the locomotion and kinematics of jellyfish. Modifications were made to the governing equations for jellyfish locomotion that accounted for geometric differences between biology and the robotic design. In particular, the capability of the model to account for the mass and geometry of the robot design has been added for better …

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Nonideal Mhd Simulation Of Hl Tau Disk: Formation Of Rings, Xiao Hu, Zhaohuan Zhu, Satoshi Okuzumi, Xue-Ning Bai, Lile Wang, Kengo Tomida, James M. Stone Oct 2019

Nonideal Mhd Simulation Of Hl Tau Disk: Formation Of Rings, Xiao Hu, Zhaohuan Zhu, Satoshi Okuzumi, Xue-Ning Bai, Lile Wang, Kengo Tomida, James M. Stone

Physics & Astronomy Faculty Research

Recent high-resolution observations unveil ring structures in circumstellar disks. The origin of these rings has been widely investigated under various theoretical scenarios. In this work we perform global 3D nonideal MHD simulations including effects from both ohmic resistivity and ambipolar diffusion (AD) to model the HL Tau disk. The nonideal MHD diffusion profiles are calculated based on the global dust evolution calculation including sintering effects. Disk ionization structure changes dramatically across the snow line due to the change of dust size distribution close to the snow line of major volatiles. We find that accretion is mainly driven by disk wind. …

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Effects Of Rate Of Drying, Life History Phase, And Ecotype On The Ability Of The Moss Bryum Argenteum To Survive Desiccation Events And The Influence On Conservation And Selection Of Material For Restoration, Joshua Lee Greenwood, Lloyd R. Stark, Lindsay P. Chiquoine Oct 2019

Effects Of Rate Of Drying, Life History Phase, And Ecotype On The Ability Of The Moss Bryum Argenteum To Survive Desiccation Events And The Influence On Conservation And Selection Of Material For Restoration, Joshua Lee Greenwood, Lloyd R. Stark, Lindsay P. Chiquoine

Life Sciences Faculty Research

Desiccation stress is frequently experienced by the moss Bryum argenteum and can influence survival, propagation and niche selection. We attempted to disentangle the interacting factors of life history phase (five categories) and rate of desiccation (time allotted for induction of desiccation tolerance) for 13 ecotypes of B. argenteum. Using chlorophyll fluorescence as a stress index, we determined how these parameters influenced desiccation tolerance. Rate of drying and life phase significantly affected desiccation tolerance. The reaction norms of desiccation tolerance displayed by the 13 ecotypes showed a substantial degree of variation in phenotypic plasticity. We observed differences in survival and fluorescence …

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Synchrotron Self-Compton Emission From External Shocks As The Origin Of The Sub-Tev Emission In Grb 180720b And Grb 190114c, Xiang-Yu Wang, Ruo-Yu Liu, Hai-Ming Zhang, Shao-Qiang Xi, Bing Zhang Oct 2019

Synchrotron Self-Compton Emission From External Shocks As The Origin Of The Sub-Tev Emission In Grb 180720b And Grb 190114c, Xiang-Yu Wang, Ruo-Yu Liu, Hai-Ming Zhang, Shao-Qiang Xi, Bing Zhang

Physics & Astronomy Faculty Research

Recently, very high-energy photons above 100 GeV were reported to be detected from GRB 190114C and GRB 180720B at, respectively, 100–1000 s and 10 hr after the burst. We model the available broadband data of both GRBs with the synchrotron plus synchrotron self-Compton (SSC) emission of the afterglow shocks. We find that the sub-TeV emission of GRB 180720B can be interpreted as the SSC emission from afterglow shocks expanding in a constant-density circumburst medium. The SSC emission of GRB 190114C dominates over the synchrotron component from GeV energies at ~100 s, which can explain the possible hard spectrum of the …

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Changes In Pm2.5 Peat Combustion Source Profiles With Atmospheric Aging In An Oxidation Flow Reactor, Judith C. Chow, Junji Cao, Lung-Wen Anthony Chen, Xiaoliang Wang, Qiyuan Wang, Jie Tian, Steven Sai Hang Ho, Adam C. Watts, Tessa B. Carlson, Steven D. Kohl, John G. Watson Oct 2019

Changes In Pm2.5 Peat Combustion Source Profiles With Atmospheric Aging In An Oxidation Flow Reactor, Judith C. Chow, Junji Cao, Lung-Wen Anthony Chen, Xiaoliang Wang, Qiyuan Wang, Jie Tian, Steven Sai Hang Ho, Adam C. Watts, Tessa B. Carlson, Steven D. Kohl, John G. Watson

Environmental & Occupational Health Faculty Publications

Smoke from laboratory chamber burning of peat fuels from Russia, Siberia, the USA (Alaska and Florida), and Malaysia representing boreal, temperate, subtropical, and tropical regions was sampled before and after passing through a potential-aerosol-mass oxidation flow reactor (PAM-OFR) to simulate intermediately aged (∼2 d) and well-aged (∼7 d) source profiles. Species abundances in PM2.5 between aged and fresh profiles varied by several orders of magnitude with two distinguishable clusters, centered around 0.1 % for reactive and ionic species and centered around 10 % for carbon. Organic carbon (OC) accounted for 58 %–85 % of PM2.5 mass in fresh profiles with …

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"Double-Tracking" Characteristics Of The Spectral Evolution Of Grb 131231a: Synchrotron Origin?, Liang Li, Jin-Jun Geng, Yan-Zhi Meng, Xue-Feng Wu, Yong-Feng Huang, Yu Wang, Rahim Moradi, Lucas Uhm, Bing Zhang Oct 2019

"Double-Tracking" Characteristics Of The Spectral Evolution Of Grb 131231a: Synchrotron Origin?, Liang Li, Jin-Jun Geng, Yan-Zhi Meng, Xue-Feng Wu, Yong-Feng Huang, Yu Wang, Rahim Moradi, Lucas Uhm, Bing Zhang

Physics & Astronomy Faculty Research

The characteristics of the spectral evolution of the prompt emission of gamma-ray bursts (GRBs), which are closely related to the radiation mechanism (synchrotron or photosphere), are still an unsolved subject. Here, by performing the detailed time-resolved spectral fitting of GRB 131231A, which has a very bright and well-defined single pulse, some interesting spectral evolution features have been found. (i) Both the low-energy spectral index α and the peak energy E p exhibit the "flux-tracking" pattern ("double-tracking" characteristics). (ii) The parameter relations, i.e., F (the energy flux)-α, F–E p, and E p–α, along with the analogous Yonetoku E p–L γ,iso relation …

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An Ideal Testbed For Planet-Disk Interaction: Two Giant Protoplanets In Resonance Shaping The Pds 70 Protoplanetary Disk, Jaehan Bae, Zhaohuan Zhu, Clément Baruteau, Myriam Benisty, Cornelis P. Dullemong, Stefano Facchini, Andrea Isella, Miriam Keppler, Laura M. Pérez, Richard Teague Oct 2019

An Ideal Testbed For Planet-Disk Interaction: Two Giant Protoplanets In Resonance Shaping The Pds 70 Protoplanetary Disk, Jaehan Bae, Zhaohuan Zhu, Clément Baruteau, Myriam Benisty, Cornelis P. Dullemong, Stefano Facchini, Andrea Isella, Miriam Keppler, Laura M. Pérez, Richard Teague

Physics & Astronomy Faculty Research

While numerical simulations have been playing a key role in the studies of planet–disk interaction, testing numerical results against observations has been limited so far. With the two directly imaged protoplanets embedded in its circumstellar disk, PDS 70 offers an ideal testbed for planet–disk interaction studies. Using two-dimensional hydrodynamic simulations we show that the observed features can be well explained with the two planets in formation, providing strong evidence that previously proposed theories of planet–disk interaction are in action, including resonant migration, particle trapping, size segregation, and filtration. Our simulations suggest that the two planets are likely in 2:1 mean …

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Diagnosing 0.1–10 Au Scale Morphology Of The Fu Ori Disk Using Alma And Vlti/Gravity, Hauyu Baobab Liu, Antoine Merand, Joel D. Green, Sebastian Perez, Antonio S. Hales, Yao-Lun Yang, Michael M. Dunham, Yasuhiro Hasegawa, Thomas Henning, Roberto Galvin-Madrid, Agnes Kospal, Michihiro Takami, Eduardo I. Vorobyov, Zhaohuan Zhu Oct 2019

Diagnosing 0.1–10 Au Scale Morphology Of The Fu Ori Disk Using Alma And Vlti/Gravity, Hauyu Baobab Liu, Antoine Merand, Joel D. Green, Sebastian Perez, Antonio S. Hales, Yao-Lun Yang, Michael M. Dunham, Yasuhiro Hasegawa, Thomas Henning, Roberto Galvin-Madrid, Agnes Kospal, Michihiro Takami, Eduardo I. Vorobyov, Zhaohuan Zhu

Physics & Astronomy Faculty Research

We report new Atacama Large Millimeter/submillimeter Array Band 3 (86–100 GHz; ~80 mas angular resolution) and Band 4 (146–160 GHz; ~50 mas angular resolution) observations of the dust continuum emission toward the archetypal and ongoing accretion burst young stellar object FU Ori, which simultaneously covered its companion, FU Ori S. In addition, we present near-infrared (2–2.45 μm) observations of FU Ori taken with the General Relativity Analysis via VLT InTerferometrY (GRAVITY; ~1 mas angular resolution) instrument on the Very Large Telescope Interferometer (VLTI). We find that the emission in both FU Ori and FU Ori S at (sub)millimeter and near-infrared …

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A Dynamic Quantitative Microbial Risk Assessment For Norovirus In Potable Reuse System, Erfaneh Amoueyan, Sajjad Ahmad, Joseph N.S. Eisenberg, Daniel Gerrity Oct 2019

A Dynamic Quantitative Microbial Risk Assessment For Norovirus In Potable Reuse System, Erfaneh Amoueyan, Sajjad Ahmad, Joseph N.S. Eisenberg, Daniel Gerrity

Civil and Environmental Engineering and Construction Faculty Research

This study describes the results of a dynamic quantitative microbial risk assessment (QMRA) for norovirus (NoV) that was used to evaluate the relative significance of foodborne, person-to-person, and person-to-sewage-to-person transmission pathways. This last pathway was incorporated into simulated potable reuse systems to evaluate the adequacy of typical treatment trains, operational conditions, and regulatory frameworks. The results confirm that secondary and foodborne transmission dominate the overall risk calculation and that waterborne NoV likely contributes no appreciable public health risk, at least in the scenarios modeled in this study. De facto reuse with an environmental buffer storage time of at least 30 …

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The Frb 121102 Host Is Atypical Among Nearby Fast Radio Bursts, Ye Li, Bing Zhang, Kentaro Nagamine, Jingjing Shi Oct 2019

The Frb 121102 Host Is Atypical Among Nearby Fast Radio Bursts, Ye Li, Bing Zhang, Kentaro Nagamine, Jingjing Shi

Physics & Astronomy Faculty Research

We search for host galaxy candidates of nearby fast radio bursts (FRBs), FRB 180729.J1316+55, FRB 171020, FRB 171213, FRB 180810.J1159+83, and FRB 180814.J0422+73 (the second repeating FRB). We compare the absolute magnitudes and the expected host dispersion measure DMhost of these candidates with that of the first repeating FRB, FRB 121102, as well as those of long gamma-ray bursts (LGRBs) and superluminous supernovae (SLSNe), the proposed progenitor systems of FRB 121102. We find that while the FRB 121102 host is consistent with those of LGRBs and SLSNe, the nearby FRB host candidates, at least for FRB 180729.J1316+55, FRB 171020, and …

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Reproduction And Dispersal Of Biological Soil Crust Organisms, Steven D. Warren, Larry L. St. Clair, Lloyd R. Stark, Louise A. Lewis, Nuttapon Pombubpa, Tania Kurbessoian, Jason E. Stajich, Zachary T. Aanderud Oct 2019

Reproduction And Dispersal Of Biological Soil Crust Organisms, Steven D. Warren, Larry L. St. Clair, Lloyd R. Stark, Louise A. Lewis, Nuttapon Pombubpa, Tania Kurbessoian, Jason E. Stajich, Zachary T. Aanderud

Life Sciences Faculty Research

Biological soil crusts (BSCs) consist of a diverse and highly integrated community of organisms that effectively colonize and collectively stabilize soil surfaces. BSCs vary in terms of soil chemistry and texture as well as the environmental parameters that combine to support unique combinations of organisms—including cyanobacteria dominated, lichen-dominated, and bryophyte-dominated crusts. The list of organismal groups that make up BSC communities in various and unique combinations include—free living, lichenized, and mycorrhizal fungi, chemoheterotrophic bacteria, cyanobacteria, diazotrophic bacteria and archaea, eukaryotic algae, and bryophytes. The various BSC organismal groups demonstrate several common characteristics including—desiccation and extreme temperature tolerance, production of various …

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Relativistic Astronomy. Iii. Test Of Special Relativity Via Doppler Effect, Yuan-Pei Yang, Jin-Peng Zhu, Bing Zhang Sep 2019

Relativistic Astronomy. Iii. Test Of Special Relativity Via Doppler Effect, Yuan-Pei Yang, Jin-Peng Zhu, Bing Zhang

Physics & Astronomy Faculty Research

The "Breakthrough Starshot" program is planning to send transrelativistic probes to travel to nearby stellar systems within decades. Because the probe velocity is designed to be a good fraction of the light speed, Zhang & Li recently proposed that these transrelativistic probes can be used to study astronomical objects and to test special relativity. In this work, we propose some methods to test special relativity and constrain photon mass using the Doppler effect with the images and spectral features of astronomical objects as observed in the transrelativistic probes. We introduce more general theories to set up the framework of testing …

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A Global View Of The Inner Accretion And Ejection Flow Around Super Massive Black Holes, Margherita Giustini, Daniel Proga Sep 2019

A Global View Of The Inner Accretion And Ejection Flow Around Super Massive Black Holes, Margherita Giustini, Daniel Proga

Physics & Astronomy Faculty Research

Context. Understanding the physics and geometry of accretion and ejection around super massive black holes (SMBHs) is important to understand the evolution of active galactic nuclei (AGN) and therefore of the large scale structures of the Universe. Aims. We aim at providing a simple, coherent, and global view of the sub-parsec accretion and ejection flow in AGN with varying Eddington ratio, ṁ, and black hole mass, MBH. Methods. We made use of theoretical insights, results of numerical simulations, as well as UV and X-ray observations to review the inner regions of AGN by including different accretion and ejection modes, with …

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Numerical Simulation Based Targeting Of The Magushan Skarn Cu-Mo Deposit, Middle-Lower Yangtze Metallogenic Belt, China, Xunyu Hu, Xiaohui Li, Feng Yuan, Alison Ord, Simon M. Jowitt, Yue Li, Wenqiang Dai, Rui Ye, Taofa Zhou Sep 2019

Numerical Simulation Based Targeting Of The Magushan Skarn Cu-Mo Deposit, Middle-Lower Yangtze Metallogenic Belt, China, Xunyu Hu, Xiaohui Li, Feng Yuan, Alison Ord, Simon M. Jowitt, Yue Li, Wenqiang Dai, Rui Ye, Taofa Zhou

Geoscience Faculty Publications

The Magushan Cu–Mo deposit is a skarn deposit within the Nanling–Xuancheng mining district of the Middle-Lower Yangtze River Metallogenic Belt (MLYRMB), China. This study presents the results of a new numerical simulation that models the ore-forming processes that generated the Magushan deposit and enables the identification of unexplored areas that have significant exploration potential under areas covered by thick sedimentary sequences that cannot be easily explored using traditional methods. This study outlines the practical value of numerical simulation in determining the processes that operate during mineral deposit formation and how this knowledge can be used to enhance exploration targeting in …

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Polar Alignment Of A Protoplanetary Disc Around An Eccentric Binary – Iii. Effect Of Disc Mass, Rebecca G. Martin, Stephen H. Lubow Sep 2019

Polar Alignment Of A Protoplanetary Disc Around An Eccentric Binary – Iii. Effect Of Disc Mass, Rebecca G. Martin, Stephen H. Lubow

Physics & Astronomy Faculty Research

An initially sufficiently misaligned low-mass protoplanetary disc around an eccentric binary undergoes damped nodal oscillations of tilt angle and longitude of ascending node. Dissipation causes evolution towards a stationary state of polar alignment in which the disc lies perpendicular to the binary orbital plane with angular momentum aligned to the eccentricity vector of the binary. We use hydrodynamic simulations and analytical methods to investigate how the mass of the disc affects this process. The simulations suggest that a disc with non-zero mass settles into a stationary state in the frame of the binary, the generalized polar state, at somewhat lower …

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The Radial Distribution Of Dust Particles In The Hl Tau Disk From Alma And Vla Observations, Carlos Carrasco-Gonzalez, Anibal Sierra, Mario Flock, Zhaohuan Zhu, Thomas Henning, Claire Chandler, Roberto Galvan-Madrid, Enrique Macias, Guillem Anglada, Hendrik Linz, Mayra Osorio, Luis F. Rodriguez, Leonardo Testi, Jose M. Torrelles, Laura Perez, Yao Liu Sep 2019

The Radial Distribution Of Dust Particles In The Hl Tau Disk From Alma And Vla Observations, Carlos Carrasco-Gonzalez, Anibal Sierra, Mario Flock, Zhaohuan Zhu, Thomas Henning, Claire Chandler, Roberto Galvan-Madrid, Enrique Macias, Guillem Anglada, Hendrik Linz, Mayra Osorio, Luis F. Rodriguez, Leonardo Testi, Jose M. Torrelles, Laura Perez, Yao Liu

Physics & Astronomy Faculty Research

Understanding planet formation requires one to discern how dust grows in protoplanetary disks. An important parameter to measure in disks is the maximum dust grain size present. This is usually estimated through measurements of the dust opacity at different millimeter wavelengths assuming optically thin emission and dust opacity dominated by absorption. However, Atacama Large Millimeter/submillimeter Array (ALMA) observations have shown that these assumptions might not be correct in the case of protoplanetary disks, leading to overestimation of particle sizes and to underestimation of the disk's mass. Here, we present an analysis of high-quality ALMA and Very Large Array images of …

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Literature Review: Biocement For Stabilization Of Expansive Soils In Las Vegas, Nevada, Silva Topchyan, Moses Karakouzian Sep 2019

Literature Review: Biocement For Stabilization Of Expansive Soils In Las Vegas, Nevada, Silva Topchyan, Moses Karakouzian

LSAMP Poster Presentations

The aim of this study was to present a possibility for the use of biocementon expansive clay. Expansive soil is a type of clay when exposed to water and moisture changes its volume. Due to the clays swelling and shrinkage behavior itsdifficult to use it in engineering and construction projects, therefore costly and unhealthy techniques have been used to stabiliseexpansive soil in order to address the problem [12]. A possible healthy and environmentally friendly solution is Biocement which uses microbial induced calcite precipitation (MICP) in order to help aggregate soil to form a stable cementitiousmaterial. MICP isdependent on the innate …

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Gamma-Ray Bursts Induced By Turbulent Reconnection, A. Lazarian, Bing Zhang, Siyao Xu Sep 2019

Gamma-Ray Bursts Induced By Turbulent Reconnection, A. Lazarian, Bing Zhang, Siyao Xu

Physics & Astronomy Faculty Research

We revisit the Internal-Collision-induced MAgnetic Reconnection and Turbulence model of gamma-ray bursts (GRBs) in view of the advances made in understanding of both relativistic magnetic turbulence and relativistic turbulent magnetic reconnection. We identify the kink instability as the most natural way of changing the magnetic configuration to release the magnetic free energy through magnetic reconnection, as well as driving turbulence that enables fast turbulent reconnection. We show that this double role of the kink instability is important for explaining the prompt emission of GRBs. Our study confirms the critical role that turbulence plays in boosting reconnection efficiency in GRBs and …

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Photoionization Calculations Of The Radiation Force Due To Spectral Lines In Agns, Randall C. Dannen, Daniel Proga, Timothy R. Kallman, Tim Waters Sep 2019

Photoionization Calculations Of The Radiation Force Due To Spectral Lines In Agns, Randall C. Dannen, Daniel Proga, Timothy R. Kallman, Tim Waters

Physics & Astronomy Faculty Research

One of the main mechanisms that could drive mass outflows in active galactic nuclei (AGNs) is radiation pressure due to spectral lines. Although straightforward to understand, the actual magnitude of the radiation force is challenging to compute because the force depends on the physical conditions in the gas, as well as the strength, spectral energy distribution (SED), and geometry of the radiation field. We present results from our photoionization and radiation transfer calculations of the force multiplier, M(ξ, t), using the same radiation field to compute the gas photoionization and thermal balance. We assume low gas density (n = 104 …

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Closing The Nuclear Fuel Cycle With A Simplified Minor Actinide Lanthanide Separation Process (Alsep) And Additive Manufacturing, Artem V. Gelis, Peter Kozak, Andrew T. Breshears, M. Alex Brown, Cari Launiere, Emily L. Campbell, Gabreil B. Hall, Tatiana G. Levitskaia, Vanessa E. Holfeltz, Gregg J. Lumetta Sep 2019

Closing The Nuclear Fuel Cycle With A Simplified Minor Actinide Lanthanide Separation Process (Alsep) And Additive Manufacturing, Artem V. Gelis, Peter Kozak, Andrew T. Breshears, M. Alex Brown, Cari Launiere, Emily L. Campbell, Gabreil B. Hall, Tatiana G. Levitskaia, Vanessa E. Holfeltz, Gregg J. Lumetta

Chemistry and Biochemistry Faculty Research

Expanded low-carbon baseload power production through the use of nuclear fission can be enabled by recycling long-lived actinide isotopes within the nuclear fuel cycle. This approach provides the benefits of (a) more completely utilizing the energy potential of mined uranium, (b) reducing the footprint of nuclear geological repositories, and (c) reducing the time required for the radiotoxicity of the disposed waste to decrease to the level of uranium ore from one hundred thousand years to a few hundred years. A key step in achieving this goal is the separation of long-lived isotopes of americium (Am) and curium (Cm) for recycle …

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Nitric Oxide Is Involved In Heavy Ion-Induced Non-Targeted Effects In Human Fibroblasts, Megumi Hada, Premkumar B. Saganti, Francis A. Cucinotta Sep 2019

Nitric Oxide Is Involved In Heavy Ion-Induced Non-Targeted Effects In Human Fibroblasts, Megumi Hada, Premkumar B. Saganti, Francis A. Cucinotta

Health Physics & Diagnostic Sciences Faculty Publications

Previously, we investigated the dose response for chromosomal aberration (CA) for exposures corresponding to less than one particle traversal per cell nucleus by high energy and charge (HZE) particles, and showed that the dose responses for simple exchanges for human fibroblast irradiated under confluent culture conditions were best fit by non-linear models motivated by a non-targeted effect (NTE). Our results suggested that the simple exchanges in normal human fibroblasts have an important NTE contribution at low particle fluence. Nitric oxide (NO) has been reported as a candidate for intercellular signaling for NTE in many studies. In order to estimate the …

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Limits On The Weak Equivalence Principle And Photon Mass With Frb 121102 Subpulses, Nan Xing, He Gao, Jun-Jie Wei, Zhengxiang Li, Weiyang Wang, Bing Zhang, Xue-Feng Wu, Peter Meszaros Sep 2019

Limits On The Weak Equivalence Principle And Photon Mass With Frb 121102 Subpulses, Nan Xing, He Gao, Jun-Jie Wei, Zhengxiang Li, Weiyang Wang, Bing Zhang, Xue-Feng Wu, Peter Meszaros

Physics & Astronomy Faculty Research

Fast radio bursts (FRBs) are short-duration (~millisecond) radio transients with cosmological origin. The simple sharp features of the FRB signal have been utilized to probe two fundamental laws of physics, namely, testing Einstein's weak equivalence principle and constraining the rest mass of the photon. Recently, Hessels et al. found that after correcting for dispersive delay, some of the bursts in FRB 121102 have complex time–frequency structures that include subpulses with a time–frequency downward drifting property. Using the delay time between subpulses in FRB 121102, here we show that the parameterized post-Newtonian parameter γ is the same for photons with different …

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Modifications Of The Cztse/Mo Back-Contact Interface By Plasma Treatments, Wenjin Chen, Teoman Taskesen, David Nowak, Ulf Mikolajczak, Mohamed H. Sayed, Devendra Pareek, Jorg Ohland, Thomas Schnabel, Erik Ahlswede, Dirk Hauschild, Lothar Weinhardt, Clemens Heske, Jurgen Parisi, Levent Gutay Aug 2019

Modifications Of The Cztse/Mo Back-Contact Interface By Plasma Treatments, Wenjin Chen, Teoman Taskesen, David Nowak, Ulf Mikolajczak, Mohamed H. Sayed, Devendra Pareek, Jorg Ohland, Thomas Schnabel, Erik Ahlswede, Dirk Hauschild, Lothar Weinhardt, Clemens Heske, Jurgen Parisi, Levent Gutay

Chemistry and Biochemistry Faculty Research

Molybdenum (Mo) is the most commonly used back-contact material for copper zinc tin selenide (CZTSe)-based thin-film solar cells. For most fabrication methods, an interfacial molybdenum diselenide (MoSe2) layer with an uncontrolled thickness is formed, ranging from a few tens of nm up to ≈1 μm. In order to improve the control of the back-contact interface in CZTSe solar cells, the formation of a MoSe2 layer with a homogeneous and defined thickness is necessary. In this study, we use plasma treatments on the as-grown Mo surface prior to the CZTSe absorber formation, which consists of the deposition of stacked metallic layers …

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Space Telescope And Optical Reverberation Mapping Project. Viii. Time Variability Of Emission And Absorption In Ngc 5548 Based On Modeling The Ultraviolet Spectrum, Gerard A. Kriss, Gisella De Rosa, Justin Ely, Bradley M. Peterson, J. Kaastra, M. Mehdipour, Gary J. Ferland, Maryamossadat Dehghanian, S. Mathur, Rick Edelson, Kirk T. Korista, N. Arav, Aaron J. Barth, Misty C. Bentz, W. Niel Brandt, D. Michael Crenshaw, E. Dalla Bonta, K. D. Kenney, C. Done, Michael Eracleous, Michael M. Fausnaugh, E. Gardner, Michael R. Goad, Catherine J. Grier, Keith Horne, Christopher S. Kochanek, I. M. Mchardy, Hagai Netzer, Anna Pancoast, L. Pei, Richard W. Pogge, Daniel Proga Aug 2019

Space Telescope And Optical Reverberation Mapping Project. Viii. Time Variability Of Emission And Absorption In Ngc 5548 Based On Modeling The Ultraviolet Spectrum, Gerard A. Kriss, Gisella De Rosa, Justin Ely, Bradley M. Peterson, J. Kaastra, M. Mehdipour, Gary J. Ferland, Maryamossadat Dehghanian, S. Mathur, Rick Edelson, Kirk T. Korista, N. Arav, Aaron J. Barth, Misty C. Bentz, W. Niel Brandt, D. Michael Crenshaw, E. Dalla Bonta, K. D. Kenney, C. Done, Michael Eracleous, Michael M. Fausnaugh, E. Gardner, Michael R. Goad, Catherine J. Grier, Keith Horne, Christopher S. Kochanek, I. M. Mchardy, Hagai Netzer, Anna Pancoast, L. Pei, Richard W. Pogge, Daniel Proga

Physics & Astronomy Faculty Research

We model the ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 obtained with the Hubble Space Telescope during the 6 month reverberation mapping campaign in 2014. Our model of the emission from NGC 5548 corrects for overlying absorption and deblends the individual emission lines. Using the modeled spectra, we measure the response to continuum variations for the deblended and absorption-corrected individual broad emission lines, the velocity-dependent profiles of Lyα and C iv, and the narrow and broad intrinsic absorption features. We find that the time lags for the corrected emission lines are comparable to those for the original data. …

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Viewing Angle Constraints On S190425z And S190426c And The Joint Gravitational-Wave/Gamma-Ray Detection Fractions For Binary Neutron Star Mergers, Hao-Ran Song, Shun-Ke Ai, Min-Hao Wang, Nan Xing, He Gao, Bing Zhang Aug 2019

Viewing Angle Constraints On S190425z And S190426c And The Joint Gravitational-Wave/Gamma-Ray Detection Fractions For Binary Neutron Star Mergers, Hao-Ran Song, Shun-Ke Ai, Min-Hao Wang, Nan Xing, He Gao, Bing Zhang

Physics & Astronomy Faculty Research

The Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo scientific collaboration (LVC) detected two binary neutron star (BNS) merger candidates, S190425z and S190426c. The Fermi-Gamma-ray Burst Monitor (GBM) observed 55.6% (for S190425z) and 100% (for S190426c) of the probability regions of both events at the respective merger times, but no gamma-ray burst (GRB) was detected in either case. The derived luminosity upper limits suggest that a short GRB similar to GRB 170817A would not be detectable for both cases due to their distances, which are larger than that of GW170817. Assuming that the jet profile obtained from GW170817/GRB 170817A is quasi-universal …

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Implementation Of National Policies For A Total Asbestos Ban: A Global Comparison, Ro-Ting Lin Phd, Lung-Chang Chien Drph, Masamine Jimba Phd, Sugio Furuya Bec, Ken Takahashi Phd Aug 2019

Implementation Of National Policies For A Total Asbestos Ban: A Global Comparison, Ro-Ting Lin Phd, Lung-Chang Chien Drph, Masamine Jimba Phd, Sugio Furuya Bec, Ken Takahashi Phd

Environmental & Occupational Health Faculty Publications

Background Two international Conventions from the International Labor Organization (ILO; C162 Asbestos Convention) and the UN (Basel Convention) offer governments guidelines for achieving a total asbestos ban policy, but the long-term effect of these Conventions on policy implementation, and the role of government effectiveness, remains unknown. We aimed to investigate associations between government ratification of the ILO and UN international Conventions, government effectiveness, and implementation of a national total asbestos ban. Methods We obtained data for year of a national asbestos ban, year of ratification of one or both international Conventions, and World Bank government effectiveness scores for 108 countries …

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