Physical Sciences and Mathematics Commons^™

Evolution Of Magnetism In The Single-Crystal Honeycomb Iridates (Na1−XLiX)2Iro3, Gang Cao, Tongfei Qi, L. Li, Jsaminka Terzic, Vincent Shian Cao, Shujuan Yuan, M. Tovar, Ganpathy Murthy, Ribhu K. Kaul

Physics and Astronomy Faculty Publications

We report the successful synthesis of single crystals of the layered iridate (Na_1−xLi_x)₂IrO₃, 0 ≤ x ≤ 0.9, and a thorough study of its structural, magnetic, thermal, and transport properties. This compound allows a controlled interpolation between Na₂IrO₃ and Li₂IrO₃, while maintaining the quantum magnetism of the honeycomb Ir⁴⁺ planes. The measured phase diagram demonstrates a suppression of the Néel temperature T_N at an intermediate x, indicating that the magnetic orders in Na₂IrO₃ and Li₂IrO_{3 …}

Nicotine Exploits A Copi-Mediated Process For Chaperone-Mediated Up-Regulation Of Its Receptors, Brandon J. Henderson, Rahul Srinivasan, Weston A. Nichols, Crystal N. Dilworth, Diana F. Gutierrez, Elisha D. W. Mackey, Sheri Mckinney, Ryan M. Drenan, Christopher I. Richards, Henry A. Lester

Chemistry Faculty Publications

Chronic exposure to nicotine up-regulates high sensitivity nicotinic acetylcholine receptors (nAChRs) in the brain. This up-regulation partially underlies addiction and may also contribute to protection against Parkinson's disease. nAChRs containing the α6 subunit (α6* nAChRs) are expressed in neurons in several brain regions, but comparatively little is known about the effect of chronic nicotine on these nAChRs. We report here that nicotine up-regulates α6* nAChRs in several mouse brain regions (substantia nigra pars compacta, ventral tegmental area, medial habenula, and superior colliculus) and in neuroblastoma 2a cells. We present evidence that a coat protein complex I (COPI)-mediated process mediates this …

Molecular Hydrogen Regulated Star Formation In Cosmological Smoothed Particle Hydrodynamics Simulations, Robert Thompson, Kentaro Nagamine, Jason Jaacks, Jun-Hwan Choi

Physics and Astronomy Faculty Publications

Some observations have shown that star formation (SF) correlates tightly with the presence of molecular hydrogen (H₂); therefore, it is important to investigate its implication on galaxy formation in a cosmological context. In the present work, we implement a sub-grid model (hereafter H₂-SF model) that tracks the H₂ mass fraction within our cosmological smoothed particle hydrodynamics code GADGET-3 by using an equilibrium analytic model of Krumholz et al. This model allows us to regulate the SF in our simulation by the local abundance of H₂ rather than the total cold gas density, which naturally …

Atomic Data For S Ii—Toward Better Diagnostics Of Chemical Evolution In High-Redshift Galaxies, Romas Kisielius, Varsha P. Kulkarni, Gary J. Ferland, Pavel Bogdanovich, Matt L. Lykins

Physics and Astronomy Faculty Publications

Absorption-line spectroscopy is a powerful tool used to estimate element abundances in both the nearby and distant universe. The accuracy of the abundances thus derived is naturally limited by the accuracy of the atomic data assumed for the spectral lines. We have recently started a project to perform new extensive atomic data calculations used for optical/UV spectral lines in the plasma modeling code Cloudy using state of the art quantal calculations. Here, we demonstrate our approach by focussing on S II, an ion used to estimate metallicities for Milky Way interstellar clouds as well as distant damped Lyman-alpha (DLA) and …

The Progenitors Of The Compact Early-Type Galaxies At High Redshift, Christina C. Williams, Mauro Giavalisco, Paolo Cassata, Elena Tundo, Tommy Wiklind, Yicheng Guo, Bomee Lee, Guillermo Barro, Stijn Wuyts, Eric F. Bell, Christopher J. Conselice, Avishai Dekel, Sandra M. Faber, Henry C. Ferguson, Norman A. Grogin, Nimish Hathi, Kuang-Han Huang, Dalibor D. Kocevski, Anton M. Koekemoer, David C. Koo, Swara Ravindranath, Sarah Salimbeni

Physics and Astronomy Faculty Publications

We use GOODS and CANDELS images to identify progenitors of massive (M > 10¹⁰ M _☉) compact early-type galaxies (ETGs) at z ~ 1.6. Because merging and accretion increase the size of the stellar component of galaxies, if the progenitors are among known star-forming galaxies, these must be compact themselves. We select candidate progenitors among compact Lyman-break galaxies at z ~ 3 on the basis of their mass, star-formation rate (SFR), and central stellar density, and we find that these account for a large fraction of, and possibly all, compact ETGs at z ~ 1.6. We find that …

Effects Of External Radiation Fields On Line Emission—Application To Star-Forming Regions, Marios Chatzikos, Gary J. Ferland, R. J. R. Williams, Ryan Porter, P. A. M. Vanhoof

Physics and Astronomy Faculty Publications

A variety of astronomical environments contain clouds irradiated by a combination of isotropic and beamed radiation fields. For example, molecular clouds may be irradiated by the isotropic cosmic microwave background, as well as by a nearby active galactic nucleus. These radiation fields excite atoms and molecules and produce emission in different ways. We revisit the escape probability theorem and derive a novel expression that accounts for the presence of external radiation fields. We show that when the field is isotropic the escape probability is reduced relative to that in the absence of external radiation. This is in agreement with previous …

Economic Challenges Facing Kentucky’S Electricity Generation Under Greenhouse Gas Constraints, Energy And Environment Cabinet, Commonwealth Of Kentucky, Department Of Statistics, University Of Kentucky, Center For Applied Energy Research, University Of Kentucky, Pacific Northwest National Laboratory

Statistics Reports

From the preface:

For the Energy and Environment Cabinet (EEC), which has primacy in administering most federal environmental laws and regulations at the state level, we have to understand the implications of what is arguably one of the most challenging issues to confront us—greenhouse gas (GHG) emissions and their impact on climate change. Efforts to reduce GHG or carbon dioxide (CO₂) emissions have moved beyond the point of discussion at the national level, and the United States Supreme Court has ruled that the U.S. Environmental Protection Agency (EPA) has the authority to regulate GHG emissions. Furthermore, while public …

Broadcasting With Prediction And Selective Forwarding In Vehicular Networks, Jainjun Yang, Zongming Fei

Computer Science Faculty Publications

Broadcasting in vehicular networks has attracted great interest in research community and industry. Broadcasting on disseminating information to individual vehicle beyond the transmission range is based on inter-vehicle communication systems. It is crucial to broadcast messages to other vehicles as fast as possible because the messages in vehicle communication systems are often emergency messages such as accident warning or alarm. In many current approaches, the message initiator or sender selects the node among its neighbors that is farthest away from it in the broadcasting direction and then assigns the node to rebroadcast the message once the node gets out of …

Thiol-Containing Compounds For The Removal Of Elements From Tissues And Formulations Therefor, Boyd E. Haley, David A. Atwood, Niladri Gupta

Chemistry Faculty Patents

Methods and pharmaceutical formulations for ameliorating heavy metal toxicity and/or oxidative stress are disclosed, comprising administering pharmaceutically effective amounts of ligands according to the present disclosure.

To see the remainder of the abstract, please download this patent.

Approximate Techniques In Solving Optimal Camera Placement Problems, Jian Zhao, Ruriko Yoshida, Sen-Ching Samson Cheung, David Haws

Statistics Faculty Publications

While the theoretical foundation of the optimal camera placement problem has been studied for decades, its practical implementation has recently attracted significant research interest due to the increasing popularity of visual sensor networks. The most flexible formulation of finding the optimal camera placement is based on a binary integer programming (BIP) problem. Despite the flexibility, most of the resulting BIP problems are NP-hard and any such formulations of reasonable size are not amenable to exact solutions. There exists a myriad of approximate algorithms for BIP problems, but their applications, efficiency, and scalability in solving camera placement are poorly understood. Thus, …

Conversion Of Iodide To Hypoiodous Acid And Iodine In Aqueous Microdroplets Exposed To Ozone, Elizabeth A. Pillar, Marcelo I. Guzman, Jose M. Rodriguez

Chemistry Faculty Publications

Halides are incorporated into aerosol sea spray, where they start the catalytic destruction of ozone (O₃) over the oceans and affect the global troposphere. Two intriguing environmental problems undergoing continuous research are (1) to understand how reactive gas phase molecular halogens are directly produced from inorganic halides exposed to O₃ and (2) to constrain the environmental factors that control this interfacial process. This paper presents a laboratory study of the reaction of O₃ at variable iodide (I^–) concentration (0.010–100 μM) for solutions aerosolized at 25 °C, which reveal remarkable differences in the reaction intermediates …

Upland Habitat Quality And Historic Landscape Composition Influence Genetic Variation Of A Pond-Breeding Salamander, Stephen C. Richter, Steve J. Price, Chelsea S. Kross, Jeremiah R. Alexander, Michael E. Dorcas

Forestry and Natural Resources Faculty Publications

Understanding the temporal and spatial scale at which habitat alteration impacts populations is important for conservation and management. Amphibians have declined more than other vertebrates, and pond-breeding species are particularly susceptible to habitat loss and fragmentation because they have terrestrial and aquatic life stages. One approach to management of pond-breeding species is protection of core upland habitat surrounding the breeding pond. We used genetic variation as an indicator of population status in a common amphibian species, spotted salamanders (Ambystoma maculatum), to determine how amount of suitable upland habitat relates to population status in the greater Charlotte, North Carolina, …

Detecting The Rapidly Expanding Outer Shell Of The Crab Nebula: Where To Look, Xiang Wang, Gary J. Ferland, J. A. Baldwin, E. D. Loh, C. T. Richardson

Physics and Astronomy Faculty Publications

We present a range of steady-state photoionization simulations, corresponding to different assumed shell geometries and compositions, of the unseen postulated rapidly expanding outer shell to the Crab Nebula. The properties of the shell are constrained by the mass that must lie within it, and by limits to the intensities of hydrogen recombination lines. In all cases the photoionization models predict very strong emissions from high ionization lines that will not be emitted by the Crab's filaments, alleviating problems with detecting these lines in the presence of light scattered from brighter parts of the Crab. The near-NIR [Ne VI] λ7.652 μ …

The Deep2 Galaxy Redshift Survey: Design, Observations, Data Reduction, And Redshifts, Jeffery A. Newman, Michael C. Cooper, Marc Davis, S. M. Faber, Alison L. Coil, Puragra Guhathakurta, David C. Koo, Andrew C. Phillips, Charlie Conroy, Aaron A. Dutton, Douglas P. Finkbeiner, Brian F. Gerke, David J. Rosario, Benjamin J. Weiner, Renbin Yan, Justin J. Harker, Susan A. Kassin, N. P. Konidaris, Kamson Lai, Darren S. Madgwick, K. G. Noeske, Gregory D. Wirth, A. J. Connolly, N. Kaiser, Evan N. Kirby, Brian C. Lemaux, Lihwai Lin, Jennifer M. Lotz, G. A. Luppino, C. Marinoni

Physics and Astronomy Faculty Publications

We describe the design and data analysis of the DEEP2 Galaxy Redshift Survey, the densest and largest high-precision redshift survey of galaxies at z ~ 1 completed to date. The survey was designed to conduct a comprehensive census of massive galaxies, their properties, environments, and large-scale structure down to absolute magnitude M_B = –20 at z ~ 1 via ~90 nights of observation on the Keck telescope. The survey covers an area of 2.8 deg² divided into four separate fields observed to a limiting apparent magnitude of R_AB = 24.1. Objects with z ≲ 0.7 are readily …

Supermassive Black Hole Formation At High Redshifts Via Direct Collapse: Physical Processes In The Early Stage, Jun-Hwan Choi, Isaac Shlosman, Mitchell C. Begelman

Physics and Astronomy Faculty Publications

We use numerical simulations to explore whether direct collapse can lead to the formation of supermassive black hole (SMBH) seeds at high redshifts. Using the adaptive mesh refinement code ENZO, we follow the evolution of gas within slowly tumbling dark matter (DM) halos of M_vir ~ 2 × 10⁸ M_☉ and R_vir ~ 1 kpc. For our idealized simulations, we adopt cosmologically motivated DM and baryon density profiles and angular momentum distributions. Our principal goal is to understand how the collapsing flow overcomes the centrifugal barrier and whether it is subject to fragmentation which can potentially …

Thimerosal Exposure And The Role Of Sulfation Chemistry And Thiol Availability In Autism, Janet K. Kern, Boyd E. Haley, David A. Geier, Lisa K. Sykes, Paul G. King, Mark R. Geier

Chemistry Faculty Publications

Autism spectrum disorder (ASD) is a neurological disorder in which a significant number of the children experience a developmental regression characterized by a loss of previously acquired skills and abilities. Typically reported are losses of verbal, nonverbal, and social abilities. Several recent studies suggest that children diagnosed with an ASD have abnormal sulfation chemistry, limited thiol availability, and decreased glutathione (GSH) reserve capacity, resulting in a compromised oxidation/reduction (redox) and detoxification capacity. Research indicates that the availability of thiols, particularly GSH, can influence the effects of thimerosal (TM) and other mercury (Hg) compounds. TM is an organomercurial compound (49.55% Hg …

Controlled Magnetic Reversal In Permalloy Films Patterned Into Artificial Quasicrystals, Vinayak Shantaram Bhat, J. Sklenar, B. Farmer, J. Woods, Jeffrey Todd Hastings, S. J. Lee, J. B. Ketterson, Lance E. De Long

Physics and Astronomy Faculty Publications

We have patterned novel Permalloy thin films with quasicrystalline Penrose P2 tilings and measured their dc magnetization and ferromagnetic resonance absorption. Reproducible anomalies in the hysteretic, low-field data signal a series of abrupt transitions between ordered magnetization textures, culminating in a smooth evolution into a saturated state. Micromagnetic simulations compare well to experimental dc hysteresis loops and ferromagnetic resonance spectra and indicate that systematic control of magnetic reversal and domain wall motion can be achieved via tiling design, offering a new paradigm of magnonic quasicrystals.

Amyloid Β-Peptide (1–42)-Induced Oxidative Stress In Alzheimer Disease: Importance In Disease Pathogenesis And Progression, D. Allan Butterfield, Aaron M. Swomley, Rukhsana Sultana

Chemistry Faculty Publications

Significance: Alzheimer disease (AD) is an age-related neurodegenerative disease. AD is characterized by progressive cognitive impairment. One of the main histopathological hallmarks of AD brain is the presence of senile plaques (SPs) and another is elevated oxidative stress. The main component of SPs is amyloid beta-peptide (Aβ) that is derived from the proteolytic cleavage of amyloid precursor protein.

Recent Advances: Recent studies are consistent with the notion that methionine present at 35 position of Aβ is critical to Aβ-induced oxidative stress and neurotoxicity. Further, we also discuss the signatures of oxidatively modified brain proteins, identified using redox proteomics approaches, during …

Long-Term Spectral Evolution Of Tidal Disruption Candidates Selected By Strong Coronal Lines, Chen-Wei Yang, Ting-Gui Wang, Gary J. Ferland, Weimin Yuan, Hong-Yan Zhou, Peng Jiang

Physics and Astronomy Faculty Publications

We present results of follow-up optical spectroscopic Multi-Mirror Telescope (MMT) observations of seven rare, extreme coronal line-emitting galaxies reported by Wang et al. Large variations in coronal lines are found in four objects, making them strong candidates for tidal disruption events (TDEs). For the four TDE candidates, all the coronal lines with ionization states higher than [Fe VII] disappear within 5-9 yr. The [Fe VII] line faded by a factor of about five in one object (J0952+2143) within 4 yr, whereas the line emerged in another two objects that previously did not show the line. A strong increment in the …

Constraints On Oh Megamaser Excitation From A Survey Of Oh Satellite Lines, James Mcbride, Carl Heiles, Moshe Elitzur

Physics and Astronomy Faculty Publications

We report the results of a full-Stokes survey of all four 18 cm OH lines in 77 OH megamasers (OHMs) using the Arecibo Observatory. This is the first survey of OHMs that included observations of the OH satellite lines; only four of the 77 OHMs have existing satellite line observations in the literature. Satellite line emission is detected in five sources, three of which are redetections of previously published sources. The two sources with new detections of satellite line emission are IRAS F10173+0829, which was detected at 1720 MHz, and IRAS F15107+0724, for which both the 1612 MHz and 1720 …

Is Security Sustainable?, Jeremy W. Crampton

Geography Faculty Publications

No abstract provided.

The Redshift And Mass Dependence On The Formation Of The Hubble Sequence At Z > 1 From Candels/Uds, Alice Mortlock, Christopher J. Conselice, William G. Hartley, Jamie R. Ownsworth, Caterina Lani, Asa F. L. Bluck, Omar Almaini, Kenneth Duncan, Arjen Van Der Wel, Anton M. Koekemoer, Avishai Dekel, Romeel Davé, Harry C. Ferguson, Duilia F. De Mello, Jeffrey A. Newman, Sandra M. Faber, Norman A. Grogin, Dalibor D. Kocevski, Kamson Lai

Physics and Astronomy Faculty Publications

In this paper we present a detailed study of the structures and morphologies of a sample of 1188 massive galaxies with M_* ≥ 10¹⁰ M_⊙between redshifts z = 1 and 3 within the Ultra Deep Survey (UDS) region of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) field. Using this sample we determine how galaxy structure and morphology evolve with time, and investigate the nature of galaxy structure at high redshift. We visually classify our sample into discs, ellipticals and peculiar systems and correct for redshift effects on these classifications through simulations. We find significant …

Interstellar H2O Masers From J Shocks, David Hollenbach, Moshe Elitzur, Christopher F. Mckee

Physics and Astronomy Faculty Publications

We present a model in which the 22 GHz H₂O masers observed in star-forming regions occur behind shocks propagating in dense regions (preshock density n ₀ ~ 10⁶-10⁸ cm^–3). We focus on high-velocity (v_s ≳ 30 km s^–1) dissociative J shocks in which the heat of H₂ re-formation maintains a large column of ~300-400 K gas; at these temperatures the chemistry drives a considerable fraction of the oxygen not in CO to form H₂O. The H₂O column densities, the hydrogen densities, and the warm …

The Importance Of Major Mergers In The Build Up Of Stellar Mass In Brightest Cluster Galaxies At Z = 1, C. Lidman, G. Iacobuta, A. E. Bauer, L. F. Barrientos, P. Cerulo, W. J. Couch, L. Delaye, R. Demarco, E. Ellingson, A. J. Faloon, D. Gilbank, M. Huertas-Company, S. Mei, J. Meyers, A. Muzzin, A. Noble, J. Nantais, A. Rettura, P. Rosati, R. Sánchez-Janssen, V. Strazzullo, T. M. A. Webb, G. Wilson, Renbin Yan, H. K. C. Yee

Physics and Astronomy Faculty Publications

Recent independent results from numerical simulations and observations have shown that brightest cluster galaxies (BCGs) have increased their stellar mass by a factor of almost 2 between z ∼ 0.9 and z ∼ 0.2. The numerical simulations further suggest that more than half this mass is accreted through major mergers. Using a sample of 18 distant galaxy clusters with over 600 spectroscopically confirmed cluster members between them, we search for observational evidence that major mergers do play a significant role. We find a major merger rate of 0.38 ± 0.14 mergers per Gyr at z ∼ 1. While the uncertainties, …

Tuning The JEff = 1/2 Insulating State Via Electron Doping And Pressure In The Double-Layered Iridate Sr3Ir2O7, L. Li, P. P. Kong, Tongfei Qi, C. Q. Jin, Shujuan Yuan, Lance E. Delong, P. Schlottmann, Gang Cao

Physics and Astronomy Faculty Publications

Sr₃Ir₂O₇ exhibits a novel J_eff = 1/2 insulating state that features a splitting between J_eff = 1/2 and 3/2 bands due to spin-orbit interaction. We report a metal-insulator transition in Sr3Ir2O7 via either dilute electron doping (La³⁺ for Sr²⁺) or application of high pressure up to 35 GPa. Our study of single-crystal Sr₃Ir₂O₇ and (Sr_1−xLa_x)₃Ir₂O₇ reveals that application of high hydrostatic pressure P leads to a drastic reduction in the electrical resistivity by as much …

Comparative Feedstock Analysis In Setaria Viridis L. As A Model For C4 Bioenergy Grasses And Panicoid Crop Species, Carloalberto Petti, Andrew Shearer, Mizuki Tateno, Mathew J. Ruwaya, Sue E. Nokes, Tom Brutnell, Seth Debolt

Horticulture Faculty Publications

Second generation feedstocks for bioethanol will likely include a sizable proportion of perennial C4 grasses, principally in the Panicoideae clade. The Panicoideae contain agronomically important annual grasses including Zea mays L. (maize), Sorghum bicolor (L.) Moench (sorghum), and Saccharum officinarum L. (sugar cane) as well as promising second generation perennial feedstocks including Miscanthus × giganteus and Panicum virgatum L. (switchgrass). The underlying complexity of these polyploid grass genomes is a major limitation for their direct manipulation and thus driving a need for rapidly cycling comparative model. Setaria viridis (green millet) is a rapid cycling C4 panicoid grass with a relatively …

Polypeptides, Systems, And Methods Useful For Detecting Glucose, Sylvia Daunert, Kendrick Turner, Smita Joel, Laura Rowe

Chemistry Faculty Patents

The presently-disclosed subject matter provides biosensors for detecting molecules of interest. The biosensors include a polypeptide capable of selectively-binding glucose, wherein the polypeptide molecule is selected from: an unnatural analogue of wild type glucose binding protein; a fragment of wild type glucose binding protein; and an unnatural analogue fragment of wild type glucose binding protein.

Influence Of Media Composition On The Growth Rate Of Chlorella Vulgaris And Scenedesmus Acutus Utilized For Co2 Mitigation, Czarena L. Crofcheck, Xinyi E, Aubrey Shea, Michael D. Montross, Mark Crocker, Rodney Andrews

Biosystems and Agricultural Engineering Faculty Publications

Atmospheric carbon dioxide levels have increased since the industrial revolution due to increasing combustion of fossil fuels. One possible CO₂ mitigation strategy is the use of microalgae for mitigation of CO₂. This paper focuses on the influence of media composition on the growth rate of two microalgae strains, Chlorella vulgaris and Scenedesmus actus. A KNO₃ based medium was found to work better for Chlorella, while a urea based equivalent worked better for Scenedesmus. The urea based media investigated here resulted in growth similar to that found with previously reported KNO₃ based media. …

Single-Step Electrochemical Functionalization Of Double-Walled Carbon Nanotube (Dwcnt) Membranes And The Demonstration Of Ionic Rectification, Xin Zhan, Ji Wu, Zhiqiang Chen, Bruce J. Hinds

Chemistry Faculty Publications

Carbon nanotube (CNT) membranes allow the mimicking of natural ion channels for applications in drug delivery and chemical separation. Double-walled carbon nanotube membranes were simply functionalized with dye in a single step instead of the previous two-step functionalization. Non-faradic electrochemical impedance spectra indicated that the functionalized gatekeeper by single-step modification can be actuated to mimic the protein channel under bias. This functional chemistry was proven by a highly efficient ion rectification, wherein the highest experimental rectification factor of ferricyanide was up to 14.4. One-step functionalization by electrooxidation of amine provides a simple and promising functionalization chemistry for the application of …

2,2',5',6-Tetrachloro-4-[(1S)-1-Methylpropoxy]Biphenyl, Hans-Joachim Lehmler, Huimin Wu, Sean Parkin

Chemistry Faculty Publications

In the title molecule, C₁₆H₁₄Cl₄O, the dihedral angle between the least-square planes of the benzene rings is 84.40 (7)°. No unusual intermolecular interactions are present.