Digital Commons Network^™

Electrical Impedance Imaging Of Corrosion On A Partially Accessible 2-Dimensional Region, Court Hoang, Katherine Osenbach

Mathematical Sciences Technical Reports (MSTR)

In this paper we examine the inverse problem of determining the amount of corrosion on an inaccessible surface of a two-dimensional region. Using numerical methods, we develop an algorithm for approximating corrosion profile using measurements of electrical potential along the accessible portion of the region. We also evaluate the effect of error on the problem, address the issue of ill-posedness, and develop a method of regularization to correct for this error. An examination of solution uniqueness is also presented.

Anti-Cloaking: The Mathematics Of Disguise, Theresa C. Anderson, Brooke E. Phillips

Mathematical Sciences Technical Reports (MSTR)

Recent developments in cloaking, the ability to selectively bend electromagnetic waves so as to render an object invisible, have been abundant. Based on cloaking principles, we will describe several ways to mathematically disguise objects in the context of electrical impedance imaging. Through the use of a change-of-variables scheme we show how one can make an object appear enlarged, translated, or rotated by surrounding it with a suitable "metamaterial," a man-made material that selectively redirects current. Analysis of eigenvectors and eigenvalues, which describe how current flows, follow. We prove that in order to disguise an object, a metamaterial must encompass both …

Retired A Stars And Their Companions. Iii. Comparing The Mass–Period Distributions Of Planets Around A-Type Stars And Sun-Like Stars, Brendan P. Bowler, John Asher Johnson, Geoffrey W. Marcy, Gregory W. Henry, Kathryn M. G. Peek, Debra A. Fischer, Kelsey I. Clubb, Michael C. Liu, Sabine Reffert, Christian Schwab, Thomas B. Lowe

Information Systems and Engineering Management Research Publications

We present an analysis of ∼5 years of Lick Observatory radial velocity measurements targeting a uniform sample of 31 intermediate-mass (IM) subgiants (1.5 ≲ M*/M☉≲ 2.0) with the goal of measuring the occurrence rate of Jovian planets around (evolved) A-type stars and comparing the distributions of their orbital and physical characteristics to those of planets around Sun-like stars. We provide updated orbital solutions incorporating new radial velocity measurements for five known planet-hosting stars in our sample; uncertainties in the fitted parameters are assessed using a Markov-Chain Monte Carlo method. The frequency of Jovian planets interior to 3 AU is 26+9−8%, …

Solutions Of A System Of Integral Equations In Orlicz Spaces, Ravi P. Agarwal, Donal O'Regan, Patricia J.Y. Wong

Mathematics and System Engineering Faculty Publications

We consider the following system of integral equations Ui(t) = ∫1gi(t,s)fi(s,u1(s),u2(s),...,un(s))ds, a.e. t [0,1], 1 ≤ i ≤ n. Our aim is to establish criteria such that the above system has a solution (u±,U2,... ,un) where uiLφ (Orlicz space), 1 < i < n. We further investigate the system Ui(t) = ∫1gi(t,s)fi(s,u1(s),u2(s),...,un(s))ds, a.e. t [0,1], 1 ≤ i ≤ n. and establish the existence of constant-sign solutions in Orlicz spaces, i.e., for each 1 ≤ i ≤ n, Oui > 0 and ui G L

Detection Of Psilocybin Mushroom Analogs In Chocolate: Incorporating Current Events Into The Undergraduate Teaching Laboratory, Brandon Huskins, Christopher Dockery

Faculty Articles

In this experiment, tryptamine is used as a psilocin analog and is dispersed onto a Fisher brand cellulose laboratory sponge to simulate dehydrated mushrooms. The resulting “mushroom” material is ground, molded into chocolate, and presented to student groups for real-world and applied analyses. Students isolate the tryptamine from the chocolate using their knowledge of drug chemistry, solubility, pH, extractions, etc. Qualitative analysis is conducted by comparison to standards (Thin Layer Chromatography or Gas Chromatography) and quantitative analysis is conducted by Gas Chromatography using the method of internal standards.

Joint Fire Science Program – Lake Mead National Recreation Area Revegetating Burned Arid Lands: Identifying Successful Native Species Using Trait And Competition Analysis: Quarterly Progress Report, Time Period: October 1 — December 31, 2009, Margaret N. Rees

Fire Science

• Article accepted for publication in Journal of Arid Environments.

• Recharged irrigation gel packs for outplanting and watered seed plots at Goodsprings site.

• Completed full year of seed granivory trials at Goodsprings site.

• Presented information on this Task Agreement to 4th International Fire Ecology and Management Congress.

• Maintained nursery plots and added installment of nitrogen treatment.

Lake Mead National Recreation Area Monitoring And Evaluation Of Sensitive Wildlife: Quarterly Progress Report, Period Ending December 31, 2009, Margaret N. Rees

Wildlife Monitoring

Project 1. Relict Leopard Frog Monitoring, Management, and Research

• All milestones and deliverables are on schedule
• Fall surveys at all sites have been completed
• Mark-recapture surveys scheduled for fall were completed
• Short-term habitat improvements at two sites were conducted
• RLFCT meeting was hosted
• Draft annual report was written and presented at the RLFCT meeting

Project 2. Bald Eagle Winter Monitoring and Evaluation

• All milestones and deliverables are on schedule
• An annual project review presentation was given to Clark County
• A draft final report was written and submitted to Clark County
• All data for this project was transferred to the County …

Nevada Interagency Volunteer Program: Helping Hands Across Public Lands – Phase Ii: Quarterly Progress Report, Period Covering October 1, 2009 To December 31, 2009, Margaret N. Rees

Get Outdoors Nevada

• The number of records in the volunteer database decreased by 14% over last quarter. The database now contains 5,996 records.
• Website activity increased, recording an average of 121,918 hits per month, an increase of 8% from last quarter, with an average of 9,686 pages viewed per month.
• Volunteer fall training has been completed.
• One hundred and twenty-seven people attended the Volunteer Recognition Event.

Partial Wave Analysis Of The Reaction Γp→Pω And The Search For Nucleon Resonances, M. Williams, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

An event-based partial wave analysis (PWA) of the reaction γp → pω has been performed on a high-statistics dataset obtained using the CLAS at Jefferson Lab for center-of-mass energies from threshold up to 2.4 GeV. This analysis benefits from access to the world’s first high-precision spin-density matrix element measurements, available to the event-based PWA through the decay distribution of ω → π ⁺π ⁻π⁰. The data confirm the dominance of the t-channel π⁰ exchange amplitude in the forward direction. The dominant resonance contributions are consistent with the previously identified states F₁₅(1680) and …

Differential Cross Sections And Spin Density Matrix Elements For The Reaction Γp→Pω, M. Williams, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

High-statistics differential cross sections and spin-density matrix elements for the reaction γp → pω have been measured using the CEBAF large acceptance spectrometer (CLAS) at Jefferson Lab for center-of-mass (c.m.) energies from threshold up to 2.84 GeV. Results are reported in 112 10-MeV wide c.m. energy bins, each subdivided into cos θ^ω_c.m. bins of width 0.1. These are the most precise and extensive ω photoproduction measurements to date. A number of prominent structures are clearly present in the data. Many of these have not previously been observed due to limited statistics in earlier measurements.

Highly Nitrated Cyclopropanes As New High Energy Materials: Dft Calculations On The Properties Of C3H6−N(No2)N (N=3–6), Aloysus K. Lawong, David W. Ball

Chemistry Faculty Publications

As part of a continuing study of new potential high energy materials, here we present results of calculations on cyclopropane molecules with three or more nitro groups. DFT calculations suggest that all molecules can exist as minimum-energy stationary states. Energy calculations indicate that some nitrocyclopropanes have a specific enthalpy of decomposition in excess of 8kJg⁻¹, suggesting that they be explored as new potential high energy materials.

A High-Yield Synthesis Of Chalcopyrite Cuins2 Nanoparticles With Exceptional Size Control, Aaron Thurber, Alex Punnoose

Physics Faculty Publications and Presentations

We report high-yield and efficient size-controlled syntheses of Chalcopyrite CuInS₂ nanoparticles by decomposing molecular single source precursors (SSPs) via microwave irradiation in the presence of 1,2-ethanedithiol at reaction temperatures as low as 100◦C and times as short as 30 minutes. The nanoparticles sizes were 1.8nm to 10.8 nm as reaction temperatures were varied from 100◦C to 200◦C with the bandgaps from 2.71 eV to 1.28 eV with good size control and high yields (64%–95%). The resulting nanoparticles were analyzed by XRD, UV-Vis, ICP-OES, XPS, SEM, EDS, and HRTEM. Titration studies by ¹H NMR using SSP 1 with 1,2-ethanedithiol …

Indirect Gravimetric Determination Of Waters Of Hydration, Marina C. Koether

Faculty Articles

An alternate gravimetric experiment is described that can be employed in the general chemistry or the quantitative analysis laboratory course. The procedure takes less time than conventional methods and introduces students to waters of hydration and indirect determinations.

Double Superhelix Model Of High Density Lipoprotein, Zhiping Wu, Valentin Gogonea, Xavier Lee, Mathew A. Wagner

Chemistry Faculty Publications

High density lipoprotein (HDL), the carrier of so-called “good” cholesterol, serves as the major athero-protective lipoprotein and has emerged as a key therapeutic target for cardiovascular disease. We applied small angle neutron scattering (SANS) with contrast variation and selective isotopic deuteration to the study of nascent HDL to obtain the low resolution structure in solution of the overall time-averaged conformation of apolipoprotein AI (apoA-I) versus the lipid (acyl chain) core of the particle. Remarkably, apoA-I is observed to possess an open helical shape that wraps around a central ellipsoidal lipid phase. Using the low resolution SANS shapes of the protein …

Classical Modeling Of Non-Sequential Double Ionization: Recollision, Time-Delayed Ionization, Drift, And Possible Reattachment, Stanley L. Haan, Z. S. Smith, K. N. Shomsky, P. W. Plantinga

University Faculty Publications and Creative Works

We employ 3d classical ensembles to study Non-Sequential Double Ionization (NSDI) of atoms by strong laser fields at visible and infrared wavelengths. We consider in particular the wavelength dependence of final electron drift directions and the net momentum spectra parallel to the laser polarization. We find that as the wavelength is increased the spectrum transitions from a singlet to a doublet, then to a triplet, and finally back to a doublet. We also show that electrons that escape the central potential-energy well during the pulse may nonetheless be bound to the nucleus after laser turnoff.

Fully Differential Cross Sections For The Single Ionization Of Argon By Positron Impact At Intermediate Energies, Sebastian Otranto, Ronald E. Olson

Physics Faculty Research & Creative Works

In this work, we present theoretical fully differential cross sections (FDCS) for the single ionization of argon by positron impact obtained by means of the CDW-EIS model. the impact energies considered are 113.5 eV and 200 eV. the obtained angular distributions for 2eV and 5 eV emitted electrons are compared to those obtained for electron impact under the same energetic configuration. in particular, we show that the shape of the binary structure evolves from a single peak to a two-peak structure as the projectile scattering angle is increased. Similar conclusions apply for the usually termed recoil peak structure.

1st And 2nd Order Contributions To The Double Ionization Of Argon Resulting From Positron And Electron Impact, Robert D. Dubois, O. G. De Lucio, J. Gavin

Physics Faculty Research & Creative Works

Angular dependences for electron emission resulting from single and double ionization of argon are presented for 200, 500, and 1000 eV positron and electron impact. from these data, double to single ionization ratios are determined as a function of the emission direction. at each impact energy, these ratios have different angular dependences positive and negative particle impact. the positron and electron induced ratios are analyzed to provide information about how first- and second-order double ionization mechanisms interfere and contribute to the differential electron emission.

Single Ionization Of Ne, Ar And Kr By Proton Impact: Single Differential Distributions In Energy And Angle, Sebastian Otranto, J. E. Miraglia, Ronald E. Olson

Physics Faculty Research & Creative Works

Synopsis in this work we present a theoretical study of singly differential cross sections in energy and angle for the single ionization of neon, argon and krypton by proton impact. Theoretical results obtained by means of the Continuum Distorted Wave-Eikonal initial state (CDW-EIS) model are compared to those provided by the First-Born Approximation (FBA) and the classical trajectory Monte Carlo (CTMC) method as well as to experimental data from several laboratories. We note in particular for argon, that the CDW-EIS model does not reproduce the experimental data as accurately as expected, while the CTMC instead is in very good agreement.

Exploring Differences Of Atomic And Molecular Ionization By Electron Impact, X. Ren, A. Senftleben, T. Pflüger, A. Dorn, I. Bray, D. V. Fursa, J. Colgan, M. S. Pindzola, O. Al-Hagan, Don H. Madison, J. Ullrich

Physics Faculty Research & Creative Works

Electron impact single ionization of helium and the hydrogen molecule is studied at equivalent electron kinematics to explore the differences of atomic and molecular ionization. Fully differential cross sections (FDCS) were obtained covering the whole solid angle in order to critically test theoretical calculations.

Longitudinal Recoil Ion Momentum Distributions For Proton-Argon Ionizing Collisions At Intermediate Energies, S. Otranto, Ronald E. Olson

Physics Faculty Research & Creative Works

Synopsis Proton-argon ionizing collisions at intermediate energies are studied by means of the classical trajectory Monte Carlo method (CTMC). in particular, we focus on the longitudinal and transverse recoil momentum distributions for the process. We compare the profile of the longitudinal momentum distribution at the abrupt rise region corresponding to the electron capture to the continuum (ECC) processes, with those obtained for simpler targets like H and He. Selected subsets of the data show that the recoiling multielectronic ion plays a major role in the low energy electron emission, influencing the angular asymmetry of the electronic emission.

Photoassociation Spectroscopy Of Purely Long-Range Krypton Molecules, Z. Smith, J. Banister, R. Norman, K. Hoogeboom

University Faculty Publications and Creative Works

Photoassociation spectra for purely long-range (PLR) krypton molecules are both computed and measured. The photoassociation laser is tuned just red of the 5s[3/2]2-5p[5/2]2 transition at 810.6 nm, over a frequency range in which fourteen different PLR potential wells support hundreds of vibrational bound states. In the experiment, laser light is directed into a cloud of magneto-optically trapped 84Kr atoms, and the emission of both ultraviolet photons and ions is monitored. Peaks in these signals are observed for laser frequencies within 200 MHz of the atomic resonance. Ongoing work is aimed at improving the experimental signal and understanding the degree of …

New Double Ionization Channel Uncovered In Four-Particle Dalitz Plots, Michael Schulz, M. F. Ciappina, T. Kirchner, D. Fischer, R. Moshammer, J. Ullrich

Physics Faculty Research & Creative Works

Synopsis Double ionization in 6 MeV p + He collisions was analyzed in terms of 4-particle Dalitz plots.

Triply Differential Measurements For 200 Ev E⁺-And E--Ar Collisions, O. G. De Lucio, Robert D. Dubois

Physics Faculty Research & Creative Works

Triply differential single ionization yields for projectile scattering and electron emission are presented for 200 eV positron and electron impact ionization of argon. the projectile scattering and the electron emission are observed to be different for positron and electron impact.

Electron Impact Ionization And Fragmentation Of C2h2, A. C.F. Santos, Robert D. Dubois, E. C. Montenegro

Physics Faculty Research & Creative Works

Ionization and fragmentation of C₂H₂ resulting from 750 eV electron impact is measured as a function of electron loss. Electron losses up to 400 eV are investigated. the interaction kinematics are investigated by measuring ejected electron-C₂H₂+ ion-scattered projectile coincidences and generating triply and doubly differential yields for the electron emission and projectile scattering respectively.

Theoretical & Experimental (E,2e) Studies For Electron Impact Ionization Of Argon Measured In The Perpendicular Plane, Ola Al-Hagan, Christian Kaiser, Andrew Murray, Don H. Madison

Physics Faculty Research & Creative Works

FDCS for electron impact ionization of the Argon atom with equal energy outgoing electrons ranging from 1 eV to 25 eV are studied in the perpendicular plane.

Theoretical Fully Differential Cross Sections For Transfer-Excitation Collisions, A. L. Harris, Jerry Peacher, Michael Schulz, Don H. Madison

Physics Faculty Research & Creative Works

Synopsis Transfer-excitation calculations from a full four-body theoretical model will be compared with experiment.

Double Differential Projectile Angular Distributions For Single Ionization Of Atomic Hydrogen By 75 Kev Proton Impact, A. C. Laforge, K. Egodapitiya, J. S. Alexander, A. Hasan, Michael Schulz

Physics Faculty Research & Creative Works

Synopsis Doubly differential cross sections (DDCSp) for single ionization of atomic hydrogen by 75-keV proton impact as a function of the projectile scattering angle and energy loss have been measured.

Minima In The Triple Differential Cross Sections For The Electron-Impact Ionization Of Helium, J. Colgan, C. Kaiser, A. J. Murray, O. Al-Hagan, Don H. Madison, M. S. Pindzola

Physics Faculty Research & Creative Works

We examine unusual minima found in the triple differential cross sections for the electron-impact ionization of helium for configurations where the incident electron is out-of-plane with respect to the plane in which the outgoing electrons are detected. the position of the experimentally determined minima are confirmed by time-dependent close-coupling calculations. an analysis is made of the origin of the minima in the cross section, where it is found they are due to deep destructive interference between the partial-wave amplitudes which contribute to the differential cross section.

Single And Multiple Projectile Electron-Loss And Capture Of Low Charge States Of Oxygen Beams Colliding With The Methane Molecule, A. C.F. Santos, M. M. Sant'anna, W. Wolff, G. M. Sigaud, E. C. Montenegro, Robert D. Dubois

Physics Faculty Research & Creative Works

The projectile electron loss and capture are important ionization components collision channels in dressed ion-atom and ion-molecule collisions. They play important roles in several processes connected to the penetration of neutral and charged projectiles in gases, in radiation damage and upper atmospheric physics. in this work, cross sections for total single and multiple electron loss and capture of O^-, Oo, O⁺, O²⁺ projectiles impinging on the methane molecule were measured in the 15 keV ≤ E ≤ 1000 keV energy range. in addition, an extended version of the free-collision model was employed for the calculation …

Photoassociation Spectroscopy Of Purely Long-Range Krypton Molecules, Z. Smith, J. Banister, R. Norman, K. Hoogeboom

University Faculty Publications and Creative Works

Photoassociation spectra for purely long-range (PLR) krypton molecules are both computed and measured. The photoassociation laser is tuned just red of the 5s[3/2]2-5p[5/2]2 transition at 810.6 nm, over a frequency range in which fourteen different PLR potential wells support hundreds of vibrational bound states. In the experiment, laser light is directed into a cloud of magneto-optically trapped 84Kr atoms, and the emission of both ultraviolet photons and ions is monitored. Peaks in these signals are observed for laser frequencies within 200 MHz of the atomic resonance. Ongoing work is aimed at improving the experimental signal and understanding the degree of …