Physics Commons^™

Responses Of Mn2+ Speciation In Deinococcus Radiodurans And Escherichia Coli To Γ-Radiation By Advanced Paramagnetic Resonance Methods, Ajay Sharma, Elena K. Gaidamakova, Vera Y. Matrosova, Brian Bennett, Michael J. Daly, Brian M. Hoffman

Physics Faculty Research and Publications

The remarkable ability of bacterium Deinococcus radiodurans to survive extreme doses of γ-rays (12,000 Gy), 20 times greater than Escherichia coli, is undiminished by loss of Mn-dependent superoxide dismutase (SodA). D. radiodurans radiation resistance is attributed to the accumulation of low-molecular-weight (LMW) “antioxidant” Mn²⁺–metabolite complexes that protect essential enzymes from oxidative damage. However, in vivo information about such complexes within D. radiodurans cells is lacking, and the idea that they can supplant reactive-oxygen-species (ROS)–scavenging enzymes remains controversial. In this report, measurements by advanced paramagnetic resonance techniques [electron-spin-echo (ESE)-EPR/electron nuclear double resonance/ESE envelope modulation (ESEEM)] reveal differential details …

Slip Flow Regimes And Induced Fluid Structure In Nanoscale Polymer Films: Recent Results From Molecular Dynamics Simulations, Nikolai V. Priezjev

Physics Seminars

Over the last decade, there has been enormous interest in understanding transport phenomena in micro and nanofluidic systems and, in particular, in accurate prediction of fluid flows with slip boundary conditions at liquid-solid interfaces. In this presentation we will discuss recent results obtained from molecular dynamics simulations of fluids that consist of monomers or linear polymer chains confined by crystalline surfaces. The effects of shear rate and wall lattice orientation on the slip behavior are studied for a number of material parameters of the interface, such as fluid and wall densities, wall-fluid interaction energy, polymer chain length, and wall lattice …

Cantor-Type Cylindrical-Coordinate Method For Differential Equations With Local Fractional Derivatives, Xiao-Jun Yang

Xiao-Jun Yang

In this Letter, we propose to use the Cantor-type cylindrical-coordinate method in order to investigate a family of local fractional differential operators on Cantor sets. Some testing examples are given to illustrate the capability of the proposed method for the heat-conduction equation on a Cantor set and the damped wave equation in fractal strings. It is seen to be a powerful tool to convert differential equations on Cantor sets from Cantorian-coordinate systems to Cantor-type cylindrical-coordinate systems.

Applicability Of Carbon And Boron Nitride Nanotubes As Biosensors: Effect Of Biomolecular Adsorption On The Transport Properties Of Carbon And Boron Nitride Nanotubes, Xiaoliang Zhong, Saikat Mukhopadhyay, Gowtham S, Ravindra Pandey, Shashi P. Karna

Data Science Publications

The effect of molecular adsorption on the transport properties of single walled carbon and boron nitride nanotubes (CNTs and BNNTs) is investigated using density functional theory and nonequilibrium Green’s function methods. The calculated I-V characteristics predict noticeable changes in the conductivity of semiconducting BNNTs due to physisorption of nucleic acid base molecules. Specifically, guanine which binds to the side wall of BNNT significantly enhances its conductivity by introducing conduction channels near the Fermi energy of the bioconjugated system. For metallic CNTs, a large background current masks relatively small changes in current due to the biomolecular adsorption. The results therefore suggest …

Microbeam Production Using Straight And Tapered Glass Capillaries, Asma M. Ayyad

Research and Creative Activities Poster Day

No abstract provided.

Study Of 14b Using (D,P) Reaction In Inverse Kinematics, Shadi Bedoor, Jonathan C. Lighthall, Scott T. Marley

Research and Creative Activities Poster Day

No abstract provided.

Expanded Iron Uta Spectra—Probing The Thermal Stability Limits In Agn Clouds, Gary J. Ferland, R. Kisielius, F. P. Keenan, P. A. M. Van Hoof, V. Jonauskas, Matt L. Lykins, R. L. Porter, R. J. R. Williams

Physics and Astronomy Faculty Publications

The Fe unresolved transition arrays (UTAs) produce prominent features in the ~15-17 Å wavelength range in the spectra of active galactic nuclei (AGNs). Here, we present new calculations of the energies and oscillator strengths of inner-shell lines from Fe XIV, Fe XV, and Fe XVI. These are crucial ions since they are dominant at inflection points in the gas thermal stability curve, and UTA excitation followed by autoionization is an important ionization mechanism for these species. We incorporate these, and data reported in previous papers, into the plasma simulation code Cloudy. This updated physics is subsequently employed to reconsider the …

Simulation Chamber For Space Environment Survivability Testing, Robert H. Johnson, Lisa D. Montierth

Student Showcase

A vacuum chamber was designed and built that simulates the space environment making possible the testing of material modification due to exposure of solar radiation. Critical environmental components required include an ultra high vacuum (10-9 Torr), a UV/VIS/NIR solar spectrum source, an electron gun and charge plasma, temperature extremes, and long exposure duration. To simulate the solar spectrum, a solar simulator was attached to the chamber with a range of 200nm to 2000nm. The exposure time can be accelerated by scaling the solar intensity up to four suns. A Krypton lamp imitates the 120 nm ultraviolet hydrogen Lymann alpha emission …

Optical Properties And Growth Dynamics Of Oxides On Single Crystal Ain, Jacob Bugno, Sujit Biswas

The Review: A Journal of Undergraduate Student Research

Aluminum nitride (AIN) is a novel wide bandgap semiconductor. This research focused on optical properties of AIN as well as native oxide properties of single crystal AIN. Refractive index, absorption coefficient, and oxide film thickness were measured using absorption spectrophotometer and ellipsometer. Additionally, we were also interested in characterizing the oxide and studying its growth dynamics. To achieve this, we used successive ellipsometric measurements. Transmission measurements from the spectrophotometer were analyzed, and absorption spectra between 200 and 2500 nm was numerically extracted. To analyze ellipsometric data, a two parameter analytical algorithm was used. This calculated the best fit parameters for …

Electron Penetration Ranges As A Function Of Effective Number Of Valence Electrons, Teancum Quist, Blake Moore, Greg Wilson, Jr Dennison

Posters

The Continuous-Slow-Down Approximation (CSDA) is used to create a simple composite analytical formula to estimate the range or maximum penetration depth of incident electrons into diverse materials including conductors, semiconductors, and insulators. This formula generates an approximation to the range using a single fitting parameter, N_v, described as the effective number of valence electrons. This range of the formulation extends to electrons with energies from <10 eV to >10MeV, with 20% accuracy. A list comprised of 222 materials has been collected that greatly extends the applicability of this model. Several key material constants were compiled for each material, including the atomic …

Satellite Motion In A Manev Potential With Drag, Samantha Kirk, Ioannis Haranas, Ioannis Gkigkitzis

Physics and Computer Science Faculty Publications

In this paper, we consider a satellite orbiting in a Manev gravitational potential under the influence of an atmospheric drag force that varies with the square of velocity. Using an exponential atmosphere that varies with the orbital altitude of the satellite, we examine a circular orbit scenario. In particular, we derive expressions for the change in satellite radial distance as a function of the drag force parameters and obtain numerical results. The Manev potential is an alternative to the Newtonian potential that has a wide variety of applications, in astronomy, astrophysics, space dynamics, classical physics, mechanics, and even atomic physics.

Using Physlets In Hs Physical Science, Mackay Salley, Matt Menard

Arthur Vining Davis High Impact Fellows Projects

The project proposed involves using physlets as a means of getting students engaged and delivering ideas and concepts in a novel manner. Physlets are Java applets that are designed to address a specific Physics concept. There are many similar applets for other fields such as chemlets which address Chemistry topics. There are many resources regarding physlets and we have chosen to focus on one repository, Physlet Physics by Wolfgang Christian and Mario Belloni. With the funding from the Arthur Vining Davis Jr. Grant, we can purchase a reference text and a copy of a CD with approximately three hundred physlets …

Contributions To Background Reduction And Computer Simulations For Cuore & Cuore-0, Ivo J. Plamenac

Physics

CUORE and CUORE-0 aim to observe neutrinoless double beta decay in ¹³⁰Te; observing such this particular decay would substantiate the Majorana model for the neutrino and expand our current understanding of particle physics. This report will provide an overview of the Standard Model, our current framework for particle interactions, as well as the technical details of the CUORE experiment. Over the summers of 2010 and 2011, I contributed to the efforts of the CUORE collaboration by assisting in aspects such as background reduction, and explored detector behavior using computer simulations.

Nambu-Goldstone Modes And Diffuse Deformations In Elastic Shells, Christian Santangelo

Christian Santangelo

I consider the shape of a deformed elastic shell. Using the fact that the lowest-energy, small deformations are along infinitesimal isometries of the shell's mid-surface, I describe a class of weakly stretching deformations for thin shells based on the Nambu–Goldstone modes associated with those isometries. The main result is an effective theory to describe the diffuse deformations of thin shells that incorporate stretching and bending energies. The theory recovers previous results for the propagation of a “pinch” on a cylinder. A cone, on the other hand, has two length scales governing the persistence of a pinch: one governing the relaxation …

Towards A Better Understanding Of Space-Time Causality: Kolmogorov Complexity And Causality As A Matter Of Degree, Vladik Kreinovich, Andres Ortiz

Departmental Technical Reports (CS)

Space-time causality is one of the fundamental notions of modern physics; however, it is difficult to define in observational physical terms. Intuitively, the fact that a space-time event e=(t,x) can causally influence an event e'=(t',x') means that what we do in the vicinity of e changes what we observe at e'. If we had two copies of the Universe, we could perform some action at e in one copy but not in another copy; if we then observe the difference at e', this would be an indication of causality. However, we only observe one Universe, in which we either perform …

Full Superposition Principle Is Inconsistent With Non-Deterministic Versions Of Quantum Physics, Andres Ortiz, Vladik Kreinovich

Departmental Technical Reports (CS)

Many practical systems are non-deterministic, in the sense that available information about the initial states and control values does not uniquely determine the future states. For some such systems, it is important to take quantum effects into account. For that, we need to develop non-deterministic versions of quantum physics. In this paper, we show that for non-deterministic versions of quantum physics, we cannot require superposition principle -- one of the main fundamental principles of modern quantum mechanics. Specifically, while we can consider superpositions of states corresponding to the same version of the future dynamics, it is not consistently possible to …

Electronic Spectral Properties Of The Two-Dimensional Infinite-U Hubbard Model, Ehsan Khatami, Daniel Hansen, Edward Perepelitsky, Marcos Rigol, Sriram Shastry

Faculty Publications

A strong-coupling series expansion for the Green's function and the extremely correlated Fermi liquid (ECFL) theory are used to calculate the moments of the electronic spectral functions of the infinite-U Hubbard model. Results from these two complementary methods agree very well at both low densities, where the ECFL solution is the most accurate, and at high to intermediate temperatures, where the series converge. We find that a modified first moment, which underestimates the contributions from the occupied states and is accessible in the series through the time-dependent Green's function, best describes the peak location of the spectral function in the …

Mapcores 2012-2013 Assessment Report, Kristen Nairn, Pamela L. Bacon, Jim Crumley, Lynn Ziegler

MapCores Faculty Publications

This is a report showing the assessment results for the MapCores (MAthematics, Physics, COmputer science REsearch Scholars) program at the College of Saint Benedict. Started in 2009, MapCores is a cohort-based program designed to increase women's interest and achievement in mathematics, physics, computer science and engineering. The report was submitted for the National Science Foundation grant number 0965705.

The Use Of Statistics In Experimental Physics, Thomas J. Pfaff, Maksim Sipos, M. C. Sullivan, B. G. Thompson, Max Tran

Publications and Research

Most mathematicians are aware of the importance of statistics in biological sciences, business, and economics, but are less aware that statistics is used every day in experimental physics. This paper gives three interesting examples of how statistics plays a vital role in physics. These examples use the basic statistical tools of residuals analysis and goodness of fit.

Nanobiotechnology Can Boost Crop Production And Quality: First Evidence From Increased Plant Biomass, Fruit Yield And Phytomedicine Content In Bitter Melon (Momordica Charantia), Chittaranjan Kole, Phullara Kole, K Manoj Randunu, Poonam Choudhary, Ramakrishna Podila, Pu Chen Ke, Apparao M. Rao, Richard K. Marcus

Publications

BACKGROUND:

Recent research on nanoparticles in a number of crops has evidenced for enhanced germination and seedling growth, physiological activities including photosynthetic activity and nitrogen metabolism, mRNA expression and protein level, and also positive changes in gene expression indicating their potential use in crop improvement. We used a medicinally rich vegetable crop, bitter melon, as a model to evaluate the effects of seed treatment with a carbon-based nanoparticle, fullerol [C60(OH)20], on yield of plant biomass and fruit characters, and phytomedicine contents in fruits.

RESULTS:

We confirmed the uptake, translocation and accumulation of fullerol through bright field imaging and Fourier transform …