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A Tribute To Robert U. Ayres For A Lifetime Of Work In Technological Forecasting And Related Areas, Steven M. MILLER 2019 Singapore Management University

A Tribute To Robert U. Ayres For A Lifetime Of Work In Technological Forecasting And Related Areas, Steven M. Miller

Research Collection School Of Information Systems

Bob Ayres was born in the UnitedStates in 1932. For his university studies at the bachelors, masters and PhD levels, he concentrated in physics and mathematics. When we think of Bob today, we think of his pioneering work across the areas of technological forecasting, industrial metabolism and industrial ecology, and the role of energy and thermodynamics in economic growth. How did a person with a strong fundamental education as a physicist end up as a pioneering thinker and thought leader at the intersection of energy, environment and economics?


Heavy Quarkonia Production At Lhc And Eic Using Basis Light-Front Quantization Wavefunctions, Guangyao Chen, Yang Li, Kirill Tuchin, James P. Vary 2019 Iowa State University and Georgia State University

Heavy Quarkonia Production At Lhc And Eic Using Basis Light-Front Quantization Wavefunctions, Guangyao Chen, Yang Li, Kirill Tuchin, James P. Vary

Kirill Tuchin

We study exclusive charmonium and bottomonium production in ultra-peripheral heavy-ion collisions and electron-ion collisions within the dipole picture. We employ heavy quarkonium light-front wavefunctions obtained within the basis light-front quantization framework, which has some features of the light-front holographic QCD. We focus on comparison with measurements of exclusive charmonium and bottomonium production in ultraperipheral pp, pPb and PbPb collisions at LHC and find reasonable agreement with the cross sections. We also discuss the coherent production cross-section ratios of excited states to the ground state for charmonium and bottomonium, which exhibit insensitivity to the dipole model parameters. We show that ...


Chiral Cherenkov And Chiral Transition Radiation In Anisotropic Matter, Kirill Tuchin 2019 Iowa State University

Chiral Cherenkov And Chiral Transition Radiation In Anisotropic Matter, Kirill Tuchin

Kirill Tuchin

A significant contribution to the electromagnetic radiation by a fast electric charge moving in anisotropic chiral matter arises from spontaneous photon radiation due to the chiral anomaly. While such a process, also known as the “vacuum Cherenkov radiation,” is forbidden in the QED vacuum, it can occur in chiral matter, where it is more appropriate to call it the “chiral Cherenkov radiation.” Its contribution to the radiation spectrum is of order α2 compared to α3 of the bremsstrahlung. I derive the frequency spectrum and the angular distribution of this radiation in the high energy limit. The quantum effects ...


Impact Of Domain Walls On The Chiral Magnetic Effect In Hot Qcd Matter, Kirill Tuchin 2019 Iowa State University

Impact Of Domain Walls On The Chiral Magnetic Effect In Hot Qcd Matter, Kirill Tuchin

Kirill Tuchin

The chiral magnetic effect (CME)—the separation of positive and negative electric charges along the direction of the external magnetic field in quark-gluon plasma and other topologically nontrivial media—is a consequence of the coupling of electrodynamics to the topological gluon field fluctuations that form metastable CP-odd domains. In phenomenological models it is usually assumed that the domains are uniform and the influence of the domain walls on the electric current flow is not essential. This article challenges the latter assumption. A simple model consisting of a uniform spherical domain in a uniform time-dependent magnetic field is introduced and ...


Pairwise Completely Positive Matrices And Conjugate Local Diagonal Unitary Invariant Quantum States, Nathaniel Johnston, Olivia MacLean 2019 Mount Allison University

Pairwise Completely Positive Matrices And Conjugate Local Diagonal Unitary Invariant Quantum States, Nathaniel Johnston, Olivia Maclean

Electronic Journal of Linear Algebra

A generalization of the set of completely positive matrices called pairwise completely positive (PCP) matrices is introduced. These are pairs of matrices that share a joint decomposition so that one of them is necessarily positive semidefinite while the other one is necessarily entrywise non-negative. Basic properties of these matrix pairs are explored and several testable necessary and sufficient conditions are developed to help determine whether or not a pair is PCP. A connection with quantum entanglement is established by showing that determining whether or not a pair of matrices is pairwise completely positive is equivalent to determining whether or not ...


Coinage Metal–Sulfur Complexes: Stability On Metal(111) Surfaces And In The Gas Phase, Jiyoung Lee, Theresa L. Windus, Patricia A. Thiel, James W. Evans, Da-Jiang Liu 2019 Iowa State University and Ames Laboratory

Coinage Metal–Sulfur Complexes: Stability On Metal(111) Surfaces And In The Gas Phase, Jiyoung Lee, Theresa L. Windus, Patricia A. Thiel, James W. Evans, Da-Jiang Liu

James W. Evans

We provide a comprehensive theoretical assessment at the level of density functional theory (DFT) of the stability of various coinage metal–sulfur complexes, both in the gas phase and also for the complexes adsorbed on the (111) surface of the same coinage metal. Our primary interest lies in the latter where earlier scanning tunneling microscopy (STM) experiments were interpreted to suggest the existence of adsorbed S-decorated metal trimers, sometimes as a component of more complex adlayer structures. Recent STM studies at 5 K directly observed other isolated adsorbed metal–sulfur complexes. For these adsorbed species, we calculate various aspects of ...


Coinage Metal–Sulfur Complexes: Stability On Metal(111) Surfaces And In The Gas Phase, Jiyoung Lee, Theresa L. Windus, Patricia A. Thiel, James W. Evans, Da-Jiang Liu 2019 Iowa State University and Ames Laboratory

Coinage Metal–Sulfur Complexes: Stability On Metal(111) Surfaces And In The Gas Phase, Jiyoung Lee, Theresa L. Windus, Patricia A. Thiel, James W. Evans, Da-Jiang Liu

Patricia A. Thiel

We provide a comprehensive theoretical assessment at the level of density functional theory (DFT) of the stability of various coinage metal–sulfur complexes, both in the gas phase and also for the complexes adsorbed on the (111) surface of the same coinage metal. Our primary interest lies in the latter where earlier scanning tunneling microscopy (STM) experiments were interpreted to suggest the existence of adsorbed S-decorated metal trimers, sometimes as a component of more complex adlayer structures. Recent STM studies at 5 K directly observed other isolated adsorbed metal–sulfur complexes. For these adsorbed species, we calculate various aspects of ...


Coinage Metal–Sulfur Complexes: Stability On Metal(111) Surfaces And In The Gas Phase, Jiyoung Lee, Theresa L. Windus, Patricia A. Thiel, James W. Evans, Da-Jiang Liu 2019 Iowa State University and Ames Laboratory

Coinage Metal–Sulfur Complexes: Stability On Metal(111) Surfaces And In The Gas Phase, Jiyoung Lee, Theresa L. Windus, Patricia A. Thiel, James W. Evans, Da-Jiang Liu

Theresa Windus

We provide a comprehensive theoretical assessment at the level of density functional theory (DFT) of the stability of various coinage metal–sulfur complexes, both in the gas phase and also for the complexes adsorbed on the (111) surface of the same coinage metal. Our primary interest lies in the latter where earlier scanning tunneling microscopy (STM) experiments were interpreted to suggest the existence of adsorbed S-decorated metal trimers, sometimes as a component of more complex adlayer structures. Recent STM studies at 5 K directly observed other isolated adsorbed metal–sulfur complexes. For these adsorbed species, we calculate various aspects of ...


Characteristics Of Sulfur Atoms Adsorbed On Ag(100), Ag(110), And Ag(111) As Probed With Scanning Tunneling Microscopy: Experiment And Theory, Peter M. Spurgeon, Da-Jiang Liu, Holly Walen, Junepyo Oh, Hyun Jin Yang, Yousoo Kim, Patricia A. Thiel 2019 Iowa State University

Characteristics Of Sulfur Atoms Adsorbed On Ag(100), Ag(110), And Ag(111) As Probed With Scanning Tunneling Microscopy: Experiment And Theory, Peter M. Spurgeon, Da-Jiang Liu, Holly Walen, Junepyo Oh, Hyun Jin Yang, Yousoo Kim, Patricia A. Thiel

Patricia A. Thiel

In this paper, we report that S atoms on Ag(100) and Ag(110) exhibit a distinctive range of appearances in scanning tunneling microscopy (STM) images, depending on the sample bias voltage, VS. Progressing from negative to positive VS, the atomic shape can be described as a round protrusion surrounded by a dark halo (sombrero) in which the central protrusion shrinks, leaving only a round depression. This progression resembles that reported previously for S atoms on Cu(100). We test whether DFT can reproduce these shapes and the transition between them, using a modified version of the Lang–Tersoff–Hamann ...


The Challenge For Vision Of Fluctuating Real-World Illumination, David H. Foster 2019 University of Manchester

The Challenge For Vision Of Fluctuating Real-World Illumination, David H. Foster

MODVIS Workshop

No abstract provided.


Approaching Critical Thinking Through Science, Linda A. George, Jack C. Straton 2019 Portland State University

Approaching Critical Thinking Through Science, Linda A. George, Jack C. Straton

Linda A. George

One unanticipated development of University Studies is the degree to which it rapidly became seen not just as general education, but as the replacement for all generally re quired courses. Because the natural sciences had com prised one of the distribution areas of the old program, expectations that the new program would teach science quickly flowered, although exactly what faculty mean by that term has yet to be established. In fact, discussions of what we intend by science education have brought in creased attention to these expectations as we continually revisit the goals of University Studies. The matter is far ...


Haro 11, Pox 186, And Vcc 1313: The Enigmatic Behavior Of Hi Non-Emitters, Sarah H. Taft 2019 Macalester College

Haro 11, Pox 186, And Vcc 1313: The Enigmatic Behavior Of Hi Non-Emitters, Sarah H. Taft

Macalester Journal of Physics and Astronomy

We present neutral hydrogen (HI) observations from the Very Large Array (VLA) telescope of the galaxies Haro 11, Pox 186, and VCC 1313. 24 hours of deep spectral line observation at the 21 cm line were obtained from the program 17B-287 of Haro 11, the primary galaxy studied in this capstone, and 176 and 203 respective minutes of archival VLA data at the 21 cm line were obtained from the program AS0832 of Pox 186 and VCC 1313, the secondary and tertiary sources of study for this capstone. Haro 11 is one of a very small number of local dwarf ...


Binary Neutron Star Merger Rates. Predictions From Observations Of Dwarf Galaxies And Observable Rates With Ground-Based Gravitational-Wave Detectors, Karen Perez Sarmiento 2019 Macalester College

Binary Neutron Star Merger Rates. Predictions From Observations Of Dwarf Galaxies And Observable Rates With Ground-Based Gravitational-Wave Detectors, Karen Perez Sarmiento

Macalester Journal of Physics and Astronomy

Binary Neutron Star (BNS) mergers are interesting events in the field of multi-messenger astronomy since they are sources of detectable gravitational wave signals and electromagnetic transients. Here I introduce a new method to calculate a conservative, lower-limit for the rate of BNS merger events that is proportional to the stellar mass and is based on evidence of an r-process event in the dwarf galaxy Reticulum II. Two estimates of the stellar mass in the nearby universe were made using a Schechter Mass Function and a modified version of the 2MASS Extended Source Catalog (2MASS XSC). The BNS merger event rates ...


Uv Led System For Pl Measurements On Gan Samples, Dona H. Pantova 2019 Macalester College

Uv Led System For Pl Measurements On Gan Samples, Dona H. Pantova

Macalester Journal of Physics and Astronomy

Gallium Nitride materials are direct bandgap semiconductors with important applications, such as in the production of light-emitting diodes and transistors. The process of photoluminescence, in which excited electron and holes emit electro-magnetic radiation when they recombine, can be used to study the structure and quality of Gallium Nitride materials. Due to the size of the bandgap in these materials (3.4eV), ultraviolet light is required to create electron-hole pairs in GaN. We designed and built a system, which uses ultraviolet light, to take measurements on GaN samples provided by a local company, Lightwave Photonics, who were interested in the quality ...


Investigation On The Electrical Properties Of Cdo/Zno Thin Films Using Thz Spectroscopy, Ramon Molina 2019 Macalester College

Investigation On The Electrical Properties Of Cdo/Zno Thin Films Using Thz Spectroscopy, Ramon Molina

Macalester Journal of Physics and Astronomy

In this work, we study the electrical properties of transparent conducting oxides using physical and optical techniques. The objective is to characterize the conductivity of a series of cadmium oxide zinc-oxide thin films with varying cadmium concentrations using three methods. The Hall Effect estimates carrier concentration, sheet conductivity, and carrier mobility. Optical methods, such as FTIR spectroscopy, can provide estimates of the plasma frequency, which describes a metal’s transition from being transparent to opaque to light. THz spectroscopy extracts the complex conductivity of materials in the far infrared spectrum and provides insights on the optical transport properties of conductors ...


Understanding Solar Activity During The Last 400 Years, Sam Q. Hollenbach 2019 Macalester College

Understanding Solar Activity During The Last 400 Years, Sam Q. Hollenbach

Macalester Journal of Physics and Astronomy

The solar cycle has a profound effect on both terrestrial and extra-terrestrial operations. Understanding the history of the solar cycle is necessary for studying long term trends, however older data is difficult to calibrate due to the sparsity of observations. In this paper we propose a new method for calibrating sunspot number data that does not rely on observational overlap. Initial testing shows promise in this method’s success, though more work must be done to ensure calibration consistency across all observers.


Recent Evolution Of The Eta Carinae Supernova Imposter System, Greta L. Helmel 2019 Macalester College

Recent Evolution Of The Eta Carinae Supernova Imposter System, Greta L. Helmel

Macalester Journal of Physics and Astronomy

The supernova imposter Eta Carinae and its surrounding Homunculus reflection nebula have been of great interest for the last several decades. As the most massive star known in our Galaxy, this object is of particular importance in understanding high mass loss episodes and final stages in the evolution of other similarly massive stars in the later stages of their lives. Observations using the STIS CCD Instrument have been taken over the past 20 years for both the central star and the Homunculus as part of the Hubble Space Telescope (HST) Treasury Program on Eta Carinae. Recent changes in the spectra ...


The Neutral Hydrogen Kinematics Of The Dwarf Galaxy Merger Ngc 3239, Robert N. Ford 2019 Macalester College

The Neutral Hydrogen Kinematics Of The Dwarf Galaxy Merger Ngc 3239, Robert N. Ford

Macalester Journal of Physics and Astronomy

We present H I spectral line images of the nearby dwarf galaxy NGC 3239. The galaxy’s curious morphology suggests that it is a post-merger system. We propose that NGC 3239 is a merger because it has multiple tidal tails, an enhanced velocity dispersion throughout the disk, and widespread star formation. We have produced kinematic moment maps corresponding to the H I column density, radial velocity, and velocity dispersion. Further, position velocity (P-V) slices of the galaxy were taken and three-color images were made using the SDSS G, R, and I, filters for comparison with the moment maps. These slices ...


Carrier Mobility Of Bismuth-Doped Perovskite, Kelly Flugaur-Leavitt 2019 Macalester College

Carrier Mobility Of Bismuth-Doped Perovskite, Kelly Flugaur-Leavitt

Macalester Journal of Physics and Astronomy

As renewable energy increasingly becomes a priority around the world, the demand for inexpensive, efficient solar cells is greater than ever. Lead halide perovskites show promising potential, but have their share of drawbacks that could be improved through slight changes to its elemental composition. We used time-resolved terahertz spectroscopy to probe the differences created by doping lead halide perovskites with bismuth. We found that all samples, regardless of bismuth content, had a recombination time longer than one nanosecond, and that charge-carrier mobility decreased with the addition of bismuth.


Photometry Of Star Clusters From Mendel Observatory, James Biegel 2019 Merrimack College

Photometry Of Star Clusters From Mendel Observatory, James Biegel

Across the Bridge: The Merrimack Undergraduate Research Journal

We have observed four open star clusters and three globular star clusters using Mendel Observatory’s 18” Richey-Chrétien telescope. Our photometry data was obtained using nonstandard R, G, and B filters. We plotted the results in the form of a Hertzsprung-Russell (H-R) diagram in an attempt to determine the so called “turn-off point” for the observed clusters, which is a strong indicator of age. Due to our limited sample size of stars in each cluster, we were not able to determine the turn-off points and obtain relative ages for the clusters. However, we find that the shapes of our H-R ...


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