Astrophysics and Astronomy Commons^™

Induced Ferromagnetism In Multilayered Graphene In Proximity With Cofe2o4, Himanshu Verma, Dereje Seifu, Shashi P. Karna, Haiping Hong, Mohindar S. Seehra

Faculty & Staff Scholarship

Composites of anisotropic diamagnetic multilayer Graphene (MLG) and ferrimagnetic CoFe2O4 (CFO) nanoparticles (NPs) were synthesized through a one-step sonication process in the presence of a surfactant. The samples were characterized at ambi- ent using x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, magnetic force microscopy (MFM) and magnetometry (vibrating sample magnetometer). An induced ferromagnetism was observed in MLG with saturation magnetization MS = 18 emu/g(MLG). This induced ferromagnetism is attributed to ferrimagnetic CFO uniformly distributed on the surface of diamagnetic MLG. SEM images confirm uniform dense distribu- tion of CFO nanoparticles on MLG. MFM images …

Motivations Of Educators For Participating In An Authentic Astronomy Research Experience Professional Development Program, Luisa M. Rebull, T. Roberts, W. Laurence, Michael Fitzgerald, D. A. French, Varoujan Gorjian, G. K. Squires

Research outputs 2014 to 2021

[This paper is part of the Focused Collection on Astronomy Education Research.] The NASA/IPAC Teacher Archive Research Program (NITARP) partners small groups of educators with a research astronomer for a year-long authentic research project. This program aligns well with the characteristics of high-quality professional development (PD) programs and has worked with a total of 103 educators since 2005. In this paper, surveys were explored that were obtained from 74 different educators, at up to four waypoints during the course of 13 months, incorporating data from the class of 2010 through the class of 2017. This paper investigates how participating teachers …

Multi-Telescope Radio Observations For Low Frequency Gravitational Wave Astrophysics, Megan L. Jones

Graduate Theses, Dissertations, and Problem Reports (ETD)

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has the principal goal of detecting gravitational waves (GWs) in the nanohertz part of the spectrum using pulsar timing. This thesis presents results from radio campaigns at frequencies from 322 MHz to 10 GHz aimed at both multi-messenger constraints on GW sources and improving the timing sensitivity. The primary expected source of GWs at the nanohertz frequencies to which pulsar timing is sensitive are supermassive black hole (SMBH) binaries. We investigate a purported SMBH displaced from the galactic photocenter in NGC 3115. We explore the possibilities that the source is a …

The Earth's Magnetosphere, Soren Ormseth

Undergraduate Theses, Professional Papers, and Capstone Artifacts

The Interstellar Boundary Explorer (IBEX) is an Earth orbiting satellite launched in 2008; designed to map the boundary of our Solar System. In this presentation, we focus on how data collected by the IBEX-Hi sensor can be used to map the distribution of hot ions within the Earth's magnetosphere. As opposed to other satellites, IBEX images the magnetosphere from afar rather than by going through it. An improvement on the previous imaging techniques was developed, and we compare the new results to the old.

Reactive Oxygen Species Generation In Human Cells By A Novel Magnetic Resonance Imaging Contrast Agent, Li Wang, Eric Lin, Mary J. Johansen, Timothy Madden, Edward Felix, Karen S. Martirosyan, Steven J. Frank

Physics & Astronomy Faculty Publications

The novel positive-contrast magnetic resonance imaging (MRI) marker C4 consists of an aqueous solution of cobalt chloride (CoCl 2 ) complexed with the chelator N-acetylcysteine (NAC). We evaluated whether the presence of C4 or its components would produce reactive oxygen species (ROS, including hydroxyl, peroxyl, or other reactive oxygen species) in cultured cells. Human cancer or normal cells were incubated with 1% (w/v) CoCl 2 ·6H 2 O or 2% NAC or a combination of both (1% CoCl 2 ·6H 2 O: 2% NAC in an aqueous solution, abbreviated as Co: NAC) in the presence or absence of H 2 …

Toxicity Evaluation Of A Novel Magnetic Resonance Imaging Marker Cocl2-N-Acetylcysteine In Rats, Li Wang, Mihai Gagea, Karen S. Martirosyan, Mary Johansen, Timothy Madden, Lisa Norberg, Kirk S. Culotta, Steven J. Frank

Physics & Astronomy Faculty Publications

C4 (cobalt dichloride-N-acetylcysteine [1% CoCl 2 :2% NAC]) is a novel magnetic resonance imaging contrast marker that facilitates visualization of implanted radioactive seeds in cancer brachytherapy. We evaluated the toxicity of C4. Rats were assigned to control (0% CoCl 2 :NAC), low-dose (0.1% CoCl 2 :2% NAC), reference-dose (C4), and high-dose (10% CoCl 2 :2% NAC) groups. Agent was injected into the left quadriceps femoris muscle of the rats. Endpoints were organ and body weights, hematology, and serum chemistry and histopathologic changes of tissues at 48 hours and 28 and 63 days after dosing. Student's t tests were used. No …

The Origin Of The First Neutron Star - Neutron Star Merger, K. Belczynski, A. Askar, M. Arca-Sedda, M. Chruslinska, M. Donnari, M. Giersz, M. Benacquista, R. Spurzem, D. Jin, G. Wiktorowicz, D. Belloni

Physics & Astronomy Faculty Publications

The first neutron star-neutron star (NS-NS) merger was discovered on August 17, 2017 through gravitational waves (GW170817) and followed with electromagnetic observations. This merger was detected in an old elliptical galaxy with no recent star formation. We perform a suite of numerical calculations to understand the formation mechanism of this merger. We probe three leading formation mechanisms of double compact objects: classical isolated binary star evolution, dynamical evolution in globular clusters, and nuclear cluster formation to test whether they are likely to produce NS-NS mergers in old host galaxies. Our simulations with optimistic assumptions show current NS-NS merger rates at …

Effect Of Non-Hermiticity On Adiabatic Elimination In Coupled Waveguides, Rahman Sharaf, M. Dehghani, Hamidreza Ramezani

Physics & Astronomy Faculty Publications

We investigate the influence of non-Hermiticity on the adiabatic elimination in coupled waveguides.We show that although the total norm of the system is not conserved in parity-time symmetric phase, the dark state intensity remains constant. However, in broken phase the eliminated waveguide loses its darkness, i.e., its field amplitude starts increasing. In both exact and broken phases, the effective Hamiltonian derived from the adiabatic elimination condition describes the dynamics of all states except the dark state. Specifically, it cannot predict the amplification in the intensity of the dark state. Our results can strengthen the control of the dynamics in cavities …

Galaxy And Mass Assembly (Gama): The Mechanisms For Quiescent Galaxy Formation At Z < 1, K. Rowlands, V. Wild, N. Bourne, M. Bremer, S. Brough, S. P. Driver, A. M. Hopkins, M. S. Owers, S. Phillipps, K. Pimbblet, A. E. Sansom, L. Wang, M. Alpaslan, J. Bland-Hawthorn, M. Colless, Benne W. Holwerda, E. N. Taylor

Faculty and Staff Scholarship

One key problem in astrophysics is understanding how and why galaxies switch off their star formation, building the quiescent population that we observe in the local Universe. From the Galaxy And Mass Assembly and VIsible MultiObject Spectrograph Public Extragalactic Redshift surveys, we use spectroscopic indices to select quiescent and candidate transition galaxies. We identify potentially rapidly transitioning post-starburst (PSB) galaxies and slower transitioning green-valley galaxies. Over the last 8Gyr, the quiescent population has grown more slowly in number density at high masses (M* > 1011M⊙) than at intermediate masses (M* > 1010.6M⊙). There is evolution in both the PSB and green-valley stellar …

Comparative Study Of Cv3 Carbonaceous Chondrites Allende And Bali Using Micro-Raman Spectroscopy And Sem/Eds, Raka Paul

All Graduate Theses, Dissertations, and Other Capstone Projects

The birth of the solar system (over 4 billion years) is speculated to have happened from a nebula, swirling and compacting in localized regions to eventually form the Sun and planets. This complex process consists of numerous changes and intermediary steps, yet to be fully understood. Carbonaceous chondritic meteorites are relics of that process and therefore have potential to reveal information about the formation history. Several theories have been formulated linking their composition to planet formation. This study focusses on two carbonaceous chondritic specimens, Allende and Bali, both of the group CV and petrologic type 3. CV meteorites are abundant …

Feasibility Of The Debris Ring Transit Method For The Solar-Like Star Hd 107146 By An Occulted Galaxy, L. Van Sluijs, D. A.J.H. Vaendel, Benne W. Holwerda, M. A. Kenworthy, G. Schneider

Faculty and Staff Scholarship

Occulting galaxy pairs have been used to determine the transmission and dust composition within the foreground galaxy. Observations of the nearly face-on ring-like debris disc around the solar-like star HD 107146 by HST/ACS in 2004 and HST/STIS in 2011 reveal that the debris ring is occulting an extended background galaxy over the subsequent decades. Our aim is to use 2004 Hubble Space Telescope (HST) observations of this system to model the galaxy and apply this to the 2011 observation in order to measure the transmission of the galaxy through the outer regions of the debris disc. We model the galaxy …

Rr Lyrae Calibration Using Sdss, Single-Epoch Spectroscopy, Stacy Long

Theses and Dissertations--Physics and Astronomy

I use single-epoch, SDSS spectroscopy of RR Lyraes identified in the Catalina survey to separate the spectra into same-temperature groups. Then I draw temperature-phase diagrams of the groups. I find shocked stars, improperly phased stars, low amplitude stars, and a few that are more likely eclipsing binaries. The RR Lyraes are then given precise metallicities by measurements of the CaII K and H-β, H-γ, and H-δ lines. This leads to better distance measurements, which allow me to confirm a distinction between the inner and outer galactic halo.

Magnetic Field Design To Reduce Systematic Effects In Neutron Electric Dipole Moment Measurements, James Ryan Dadisman

Theses and Dissertations--Physics and Astronomy

Charge-Conjugation (C) and Charge-Conjugation-Parity (CP) Violation is one of the three Sakharov conditions to explain via baryogenesis the observed baryon asymmetry of the universe (BAU). The Standard Model of particle physics (SM) contains sources of CP violation, but cannot explain the BAU. This motivates searches for new physics beyond the standard model (BSM) which address the Sakharov criteria, including high-precision searches for new sources of CPV in systems for which the SM contribution is small, but larger effects may be present in BSM theories. A promising example is the search for the electric dipole moment of the neutron (nEDM), which …

Future Nuisance Flooding In Norfolk, Va, From Astronomical Tides And Annual To Decadal Internal Climate Variability, A. G. Burgos, B. D. Hamlington, P. R. Thompson, R. D. Ray

OES Faculty Publications

Increasing sea level rise will lead to more instances of nuisance flooding along the Virginia coastline in the coming decades, causing road closures and deteriorating infrastructure. These minor flood events can be caused by astronomical tides alone, in addition to internal climate variability on annual to decadal timescales. An assessment of nuisance flooding from these two effects is presented up until the year 2050 for Norfolk, Virginia. The analysis of water levels indicates that nuisance flooding from tides alone in conjunction with a medium-high sea level scenario will result in flooding beginning in 2030 with frequency increasing thereafter. The addition …

Identification And Mitigation Of Narrow Spectral Artifacts That Degrade Searches For Persistent Gravitational Waves In The First Two Observing Runs Of Advanced Ligo, P. B. Covas, A. Effler, E. Goetz, P. M. Meyers, A. Neunzert, M. Oliver, B. L. Pearlstone, Volker Quetschke, Karla E. Ramirez, Darkhan Tuyenbayev

Physics & Astronomy Faculty Publications

Searches are under way in Advanced LIGO and Virgo data for persistent gravitational waves from continuous sources, e.g. rapidly rotating galactic neutron stars, and stochastic sources, e.g. relic gravitational waves from the Big Bang or superposition of distant astrophysical events such as mergers of black holes or neutron stars. These searches can be degraded by the presence of narrow spectral artifacts (lines) due to instrumental or environmental disturbances. We describe a variety of methods used for finding, identifying and mitigating these artifacts, illustrated with particular examples. Results are provided in the form of lists of line artifacts that can safely …

Pathways To The Cosmos:The Alignment Of Megalithic Tombs In Ireland And Atlantic Europe, Frank Prendergast, Gabriel Cooney

Articles

Gabriel Cooney and Frank Prendergast present the context of and outline the approach to this one-day conference organised by Archaeology Ireland on behalf of the National Monuments Service at the Department of Culture, Heritage and the Gaeltacht and the Office of Public Works to mark the European Year of Cultural Heritage 2018. The event will take place at Dublin Castle on 15 September 2018.

Block Copolymer Elastomer With Graphite Filler: Effect Of Processing Conditions And Silane Coupling Agent On The Composite Properties, Denis M. Panaitescu, Raluca Augusta Gabor, Cristian Andi Nicolae, Anca Constantina Parau, Catalin Vitelaru, Valentin Raditoiu, Mircea Chipara

Physics & Astronomy Faculty Publications

The control of morphology and interface in poly(styrene-ethylene/butylene-styrene) (SEBS) composites with graphitic fillers is extremely important for the design of piezoresistive sensors for body motion or flexible temperature sensors. The effects of a high amount of graphite (G) and silane coupling agent on the morphology and properties of SEBS composites with anisotropic mechanical properties are reported. The physical and chemical bonding of silane to both G and SEBS surface was proved by EDX and TGA results; this improved interface influenced both the thermal and mechanical properties of the composite. The vinyltriethoxysilane (VS) promoted the formation of char residue and, being …

Numerical Study Of The Relativistic Three-Body Quantization Condition In The Isotropic Approximation, Raúl A. Briceño, Maxwell T. Hansen, Stephen R. Sharpe

Physics Faculty Publications

We present numerical results showing how our recently proposed relativistic three-particle quantization condition can be used in practice. Using the isotropic (generalized s-wave) approximation, and keeping only the leading terms in the effective range expansion, we show how the quantization condition can be solved numerically in a straightforward manner. In addition, we show how the integral equations that relate the intermediate three-particle infinite-volume scattering quantity, K_df,3, to the physical scattering amplitude can be solved at and below threshold. We test our methods by reproducing known analytic results for the 1/L expansion of the threshold state, the volume …

The Encyclopedia Of Neutrosophic Researchers - Vol. 2, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

This is the second volume of the Encyclopedia of Neutrosophic Researchers, edited from materials offered by the authors who responded to my invitation. The introduction contains a short history of neutrosophics, together with links to the main papers and books. The authors who have published neutrosophic papers, books, or defended neutrosophic master theses or PhD dissertations and are not included in the two ENR volumes, are kindly invited to send their self-presentations or their CVs, a photo, and a list of neutrosophic publications to [email protected] and [email protected] to be part of a third volume.

Florentin Smarandache

Scalar Field Vacuum Expectation Value Induced By Gravitational Wave Background, Preston Jones, Patrick Mcdougall, Michael Ragsdale, Douglas Singleton

Publications

We show that a massless scalar field in a gravitational wave background can develop a non-zero vacuum expectation value. We draw comparisons to the generation of a non-zero vacuum expectation value for a scalar field in the Higgs mechanism and with the dynamical Casimir vacuum. We propose that this vacuum expectation value, generated by a gravitational wave, can be connected with particle production from gravitational waves and may have consequences for the early Universe where scalar fields are thought to play an important role.