Physical Sciences and Mathematics Commons^™

Global Patterns And Predictions Of Seafloor Biomass Using Random Forests, Chih-Lin Wei, Gilbert T. Rowe, Elva Escobar-Briones, Antje Boetius, Thomas Soltwedel, M. Julian Caley, Yousria Soliman, Falk Huettmann, Fangyuan Qu, Zishan Yu, C. Roland Pitcher, Richard L. Haedrich, Mary K. Wicksten, Michael A. Rex, Jeffrey G. Baguley, Jyotsna Sharma, Roberto Danovaro, Ian R. Macdonald, Clifton C. Nunnally, Jody W. Deming, Paul Montagna, Mélanie Lévesque, Jan Marcin Weslawski, Maria Wlodarska-Kowalczuk, Baban S. Ingole, Brian J. Bett, David S. M. Billett, Andrew Yool, Bodil A. Bluhm, Katrin Iken, Bhavani E. Narayanaswamy

Biology Faculty Publication Series

A comprehensive seafloor biomass and abundance database has been constructed from 24 oceanographic institutions worldwide within the Census of Marine Life (CoML) field projects. The machine-learning algorithm, Random Forests, was employed to model and predict seafloor standing stocks from surface primary production, water-column integrated and export particulate organic matter (POM), seafloor relief, and bottom water properties. The predictive models explain 63% to 88% of stock variance among the major size groups. Individual and composite maps of predicted global seafloor biomass and abundance are generated for bacteria, meiofauna, macrofauna, and megafauna (invertebrates and fishes). Patterns of benthic standing stocks were positive …

Upsilon(1s)->Gamma+F2'(1525); F2'(1525)->K0sk0s Decays, Raymond Mountain, Marina Artuso, S. Blusk, T. Skwarnicki

Physics - All Scholarship

We report on a study of exclusive radiative decays of the Upsilon(1S) resonance into a final state consisting of a photon and two K0s candidates. We find evidence for a signal for Upsilon(1S)->gamma f_2'(1525); f_2'(1525)->K0sK0s, at a rate (4.0+/-1.3+/-0.6)x10^{-5}, consistent with previous observations of Upsilon(1S)->gamma f_2'(1525); f_2'(1525)->K+K-, and isospin. Combining this branching fraction with existing branching fraction measurements of Upsilon(1S)->gamma f_2'(1525) and J/psi->gamma f_2'(1525), we obtain the ratio of branching fractions: B(Upsilon(1S)->gamma f_2'(1525))/B(J/psi->gamma f_2'(1525))=0.09+/-0.02, approximately consistent with expectations based on soft collinear effective theory.

Next-To-Next-To-Leading Soft-Gluon Corrections For The Top Quark Cross Section And Transverse Momentum Distribution, Nikolaos Kidonakis

Faculty Articles

I present results for top quark production in hadronic collisions at LHC and Tevatron energies. The soft-gluon corrections to the differential cross section are resummed at next-to-next-to-leading-logarithm accuracy via the two-loop soft anomalous dimension matrices. Approximate next-to-next-to-leading-order differential and total cross sections are calculated. Detailed theoretical predictions are shown for the t (t) over bar cross section and the top quark p(T) distribution at the Tevatron and the LHC.

Comparative Study Of Field Enhancement Between Isolated And Coupled Metal Nanoparticles: An Analytical Approach, Greg Sun, Jacob B. Khurgin

Physics Faculty Publications

We present an analytical model that takes into account the coupling between the surface plasmon modes in complex metal nanostructures. We apply this model to evaluate the field enhancement in the gap of two coupled Au metal spheres embedded in GaN dielectric and compare the result with that obtained by the single sphere. The results show additional improvement can be obtained in the gap depending on the width of the gap. This approach offers a clear physical insight for the enhancement and a straightforward method for optimization.

Coherent Heteroepitaxy Of Bi2se3 On Gaas (111)B, Anthony Richardella, Duming M. Zhang, Joon S. Lee, Alison E. Patteson (Koser), David W. Rench, Andrew L. Yeats, Bob B. Buckley, David D. Awschalom, Nitin Samarth

Physics - All Scholarship

We report the heteroepitaxy of single crystal thin films of Bi2Se3 on the (111)B surface of GaAs by molecular beam epitaxy. We find that Bi2Se3 grows highly c-axis oriented, with an atomically sharp interface with the GaAs substrate. By optimizing the growth of a very thin GaAs buffer layer before growing the ⁠Bi2Se3, we demonstrate the growth of thin films with atomically flat terraces over hundreds of nanometers. Initial time-resolved Kerr rotation measurements herald opportunities for probing coherent spin dynamics at the interface between a candidate topological insulator and a large class of GaAs-based heterostructures.

Effect Of A Strategically Positioned Methoxy Substituent On The Photochemistry Of 3-Aryl-3h-1-Oxacyclopenta[L]Phenanthren-2-Ones, Roshini Thumpakara, Binoy Jose, Perupparampil Unnikrishnan, Sreedharan Prathapan, Nigam Rath

Chemistry & Biochemistry Faculty Works

Irradiation of 3-methoxy-3-aryl-3H-1-oxacyclopenta[l]phenanthren-2-one derivatives 5a–d resulted in singlet-mediated decarbonylation reaction leading to the formation of phenanthrene derivatives 9a–d. The structure of the photoproduct was unequivocally established on the basis of X-ray crystallographic analysis.

Cosmic Voices: Searching For Signs Of Life Elsewhere In The Universe, Shane L. Larson

Public Talks

No abstract provided.

Strategies To Resolve The Three-Dimensional Structure Of The Genome Of Small Single-Stranded Icosahedral Viruses, Eduardo Sanz Garcia

Theses and Dissertations

The aim of this study is the three-dimensional structural characterization of the genome packaging inside viral capsids via cryo-electron microscopy and three-dimensional reconstruction. The genome of some single-stranded viruses can be densely packaged within their capsid shells. Several stretches of the genome are known to adopt stable secondary structures, however, to date, little is known about the three-dimensional organization of the genome inside their capsid shells. Two techniques have been developed to facilitate the structural elucidation of genome packaging: the asymmetric random-model method, and the symmetry-mismatch, random model method. Both techniques were successfully tested with model and experimental data. The …

An Fpga-Based System For Tracking Digital Information Transmitted Via Peer-To-Peer Protocols, Karl R. Schrader, Barry E. Mullins, Gilbert L. Peterson, Robert F. Mills

Faculty Publications

This paper presents a Field Programmable Gate Array (FPGA)-based tool designed to process file transfers using the BitTorrent Peer-to-Peer (P2P) protocol and VoIP phone calls made using the Session Initiation Protocol (SIP). The tool searches selected control messages in real time and compares the unique identifier of the shared file or phone number against a list of known contraband files or phone numbers. Results show the FPGA tool processes P2P packets of interest 92% faster than a software-only configuration and is 97.6% accurate at capturing and processing messages at a traffic load of 89.6 Mbps.

D-Dimensional Bose Gases And The Lambert W Function, Sree Ram Valluri, J Tanguay, M Gil, D J. Jeffrey

Physics and Astronomy Publications

The applications of the Lambert W function (also known as the W function) to D-dimensional Bose gases are presented. We introduce two sets of families of logarithmic transcendental equations that occur frequently in thermodynamics and statistical mechanics and present their solution in terms of the W function. The low temperature T behavior of free ideal Bose gases is considered in three and four dimensions. It is shown that near condensation in four dimensions, the chemical potential μ and pressure P can be expressed in terms of T through the W function. The low T behavior of one- and two-dimensional ideal …

Quantifying Canal Leakage Rates Using A Mass-Balance Approach And Heat-Based Hydraulic Conductivity Estimates In Selected Irrigation Canals, Western Nebraska, 2007 Through 2009, Christopher M. Hobza, Michael J. Andersen

United States Geological Survey: Water Reports and Publications

The water supply in areas of the North Platte River Basin in the Nebraska Panhandle has been designated as fully appropriated or overappropriated by the Nebraska Department of Natural Resources (NDNR). Enacted legislation (Legislative Bill 962) requires the North Platte Natural Resources District (NPNRD) and the NDNR to develop an Integrated Management Plan (IMP) to balance groundwater and surface-water supply and demand in the NPNRD. A clear understanding of the groundwater and surface-water systems is critical for the development of a successful IMP. The primary source of groundwater recharge in parts of the NPNRD is from irrigation canal leakage. Because …

Environmental Consciousness: Human Motivation For Thinking Ecologically, Rob Pigue

Student Theses 2001-2013

What is the motivation for acting environmentally? Why do people care? What is the reason for buying fluorescent bulbs and hybrid cars, energy efficient appliances and reusable water bottles? Why is it that people turn off the lights when they leave a room, turn off the faucet while brushing their teeth, and go through the inconvenience of recycling?

Humans are known to act out of self-interest. Regardless of what people do or why they do it, their motivation can always be traced back to personal gain.

So why go green? Nothing about reducing, reusing, or recycling has any direct impact …

Study On Algebras With Retractions And Planes Over A Dvr., Prosenjit Das Dr.

Doctoral Theses

Aim:The main aim of this thesis is to study the following problems:1. For a Noetherian ring R, to find a set of minimal sufficient fibre conditions for an R-algebra with a retraction to R to be an A1-fibration over R.2. To investigate sufficient conditions for a factorial A1-form, with a retraction to the base ring, to be A1.3. To investigate whether planes of the form b(X, Y)Zn – a(X, Y) are co- ordinate planes in the polynomial ring in three variables X, Y and Z over a discrete valuation ring.The 1st problem will be discussed in Chapter 3 entitled Codimension- …

Minimum Description Length Measures Of Evidence For Enrichment, Zhenyu Yang, David R. Bickel

COBRA Preprint Series

In order to functionally interpret differentially expressed genes or other discovered features, researchers seek to detect enrichment in the form of overrepresentation of discovered features associated with a biological process. Most enrichment methods treat the p-value as the measure of evidence using a statistical test such as the binomial test, Fisher's exact test or the hypergeometric test. However, the p-value is not interpretable as a measure of evidence apart from adjustments in light of the sample size. As a measure of evidence supporting one hypothesis over the other, the Bayes factor (BF) overcomes this drawback of the p-value but lacks …

Nesting Ecology Of The Mississippi And Swallow-Tailed Kite In White River National Wildlife Refuge, Arkansas, Scott James Chiavacci

Student Theses and Dissertations

The Swallow-tailed (Elanoides forficatus; STKI) and Mississippi kite (Ictinia mississippiensis; MIKI) both express relatively poor reproductive success in White River National Wildlife Refuge (WRNWR), east-central Arkansas. I studied the nesting ecology of both species in WRNWR to determine factors contributing to their low nest survival. I located 41 MIKI nests from 2008-2009 and documented 8 causes of nest failure. The overall estimated probability of nest survival was ~25%, but estimated daily nest survival varied between nest periods among and across years. I found no consistent predictors of nest survival among the variables I measured. Also, I determined snake excluder devices, …

Preliminary Analysis Of Thermally Induced Condensed Phase Electron Transfer Reactions Of Cadmium Chloride And Lead Chloride With Electropositive Metals, Vamshi Addaguduru

Student Theses and Dissertations

The thermal stabilities and thermal decomposition for the metal halides, cadmium chloride and lead chloride with electropositive metals like Mn, Zn, Cr and Fe were studied at elevated temperatures using thermal analysis techniques, thermogravimetry and differential thermal analysis using TG/DTA apparatus. The reactions of cadmium chloride and lead chloride with electropositive metals were conducted in Cu pans and found that Zinc metal may show a reaction with both CdCl2 and PbCl2; Manganese may not react with CdCl2 and may react with PbCl2; iron may react with CdCl2 but not with PbCl2 and chromium may not react with both the metal …

Preliminary Analysis Of Thermally Induced Condensed Phase Electron Transfer Reactions Of Nickel Chloride With Electropositive Metals, Rajeshwari Devi Kamineni

Student Theses and Dissertations

The thermal decomposition, dehydration and thermal stability studies of nickel (II) chloride hexahydrate and nickel (II) chloride hexahydrate with electropositive metals cobalt, cadmium, iron, chromium, zinc and manganese have been investigated by non-isothermal method using TG/DTA under argon gas flow. The thermal decomposition and dehydration reactions reveal that there is loss of six water molecules from NiCl2.6H2O. A catalytic action of Cu from Cu pans in thermal decomposition reactions of NiCl2.6H2O and NiCl2.6H2O with electropositive metals was also observed. The change in enthalpy (∆H) of the Fe and Co with NiCl2.6H2O was calculated from the TG/DTA plot onset temperature, using …

Detecting Electron Motion In Atoms And Molecules, Hua-Chieh Shao, Anthony F. Starace

Anthony F. Starace Publications

The detection of spatial and temporal electronic motion by scattering of subfemtosecond pulses of 10 keV electrons from coherent superpositions of electronic states of both H and T⁺₂ is investigated. For the H atom, we predict changes in the diffraction images that reflect the time-dependent effective radius of the electronic charge density. For an aligned T⁺₂ molecule, the diffraction image changes reflect the time-dependent localization or delocalization of the electronic charge density.

Unl Physicists Model Potential 4-D Imaging Technique, Tom Simons, Hua-Chieh Shao, Anthony F. Starace

Anthony F. Starace Publications

A long-standing goal of science is to be able to understand how matter behaves at the atomic and subatomic level. How electrons rearrange when atoms or molecules come together is the essence of chemistry, and the ability to manipulate those rearrangements is the goal of the emerging sphere of nanotechnology. A fuller understanding could lead to enormous scientific and technological breakthroughs. Unfortunately, significant problems confront scientists and engineers in attacking the question. Not only are atoms and molecules very small, requiring highly specialized equipment to "see" them, everything at the atomic level happens very, very fast. For example, an electron …

Does Entropic Gravity Bound The Masses Of The Photon And Graviton?, Jonas R. Mureika, R. B. Mann

Physics Faculty Works

If the information transfer between test particle and holographic screen in entropic gravity respects both the uncertainty principle and causality, a lower limit on the number of bits in the universe relative to its mass may be derived. Furthermore, these limits indicate particles that putatively travel at the speed of light -- the photon and/or graviton -- have a non-zero mass m≥10−68 kg. This result is found to be in excellent agreement with current experimental mass bounds on the graviton and photon, suggesting that entropic gravity may be the result of a (recent) softly-broken local symmetry. Stronger bounds emerge …

Crystalline Order On Catenoidal Capillary Bridges, Mark Bowick, Zhenwei Yao

Physics - All Scholarship

We study the defect structure of crystalline particle arrays on negative Gaussian curvature capillary bridges with vanishing mean curvature (catenoids). The threshold aspect ratio for the appearance of isolated disclinations is found and the optimal positions for dislocations determined. We also discuss the transition from isolated disclinations to scars as particle number and aspect ratio are varied.

Crystalline Order On Catenoidal Capillary Bridges, Mark Bowick, Zhenwei Yao

Physics - All Scholarship

We study the defect structure of crystalline particle arrays on negative Gaussian curvature capillary bridges with vanishing mean curvature (catenoids). The threshold aspect ratio for the appearance of isolated disclinations is found and the optimal positions for dislocations determined. We also discuss the transition from isolated disclinations to scars as particle number and aspect ratio are varied.

University Of Richmond Climate Action Plan, University Of Richmond

Plans

The Climate Action Plan for the University of Richmond establishes the framework for achieving the University’s climate action goals under the American College and University Presidents Climate Commitment. The University of Richmond’s goal is to reduce greenhouse gas emissions 30% by 2020 and 100% by 2050. In addition to emissions reduction, the Climate Action Plan articulates goals for embedding sustainability into the curricular and co-curricular aspects of a Richmond education. The plan has been developed under the leadership of the Sustainability Working Group and the University’s Sustainability Coordinator. Climate Action Plan subgroups, with representation of staff, faculty, and students, drafted …

Metastable Anions Of Dinitrobenzene: Resonances For Electron Attachment And Kinetic Energy Release, A. Mauracher, S. Denifl, A. Edtbauer, M. Hager, M. Probst, Olof E. Echt, T. D. Maerk, P. Scheier, T. A. Field, K. Graupner

Physics & Astronomy

Attachment of free, low-energy electrons to dinitrobenzene (DNB) in the gas phase leads to DNB as well as several fragment anions. DNB, (DNB-H), (DNB-NO), (DNB-2NO), and (DNB-NO(2)) are found to undergo metastable (unimolecular) dissociation. A rich pattern of resonances in the yield of these metastable reactions versus electron energy is observed; some resonances are highly isomer-specific. Most metastable reactions are accompanied by large average kinetic energy releases (KER) that range from 0.5 to 1.32 eV, typical of complex rearrangement reactions, but (1,3-DNB-H)(-) features a resonance with a KER of only 0.06 eV for loss of NO. (1,3-DNB-NO)(-) offers a rare …

Pitch Angle Scattering In The Outer Heliosheath And Formation Of The Interstellar Boundary Explorer Ribbon, Konstantin V. Gamayunov, Ming Zhang, Hamid K. Rassoul

Aerospace, Physics, and Space Science Faculty Publications

The dominant and unexpected feature in the first Interstellar Boundary EXplorer (IBEX) maps is a ribbon of the enhanced energetic neutral atom (ENA) emissions. Presenting the first results from IBEX,McComas et al. identified six possible mechanisms of ribbon formation. One of the mechanisms, the so-called secondary ENA mechanism, was already quantitatively elaborated by Heerikhuisen et al., and they successfully reproduced the main features of the ribbon. We further study the "secondary ENA" mechanism by quantifying a previously omitted stage of the proton evolution between two consecutive acts of the charge-exchange in the outer heliosheath (OHS). The main findings can be …

Pitch Aangle Scattering In The Outer Heliosheath And Formation Of The Interstellar Boundary Explorer Ribbon, Konstantin V. Gamayunov, Ming Zhang, Hamid K. Rassoul

Aerospace, Physics, and Space Science Faculty Publications

The dominant and unexpected feature in the first Interstellar Boundary EXplorer (IBEX) maps is a ribbon of the enhanced energetic neutral atom (ENA) emissions. Presenting the first results from IBEX,McComas et al. identified six possible mechanisms of ribbon formation. One of the mechanisms, the so-called secondary ENA mechanism, was already quantitatively elaborated by Heerikhuisen et al., and they successfully reproduced the main features of the ribbon. We further study the "secondary ENA" mechanism by quantifying a previously omitted stage of the proton evolution between two consecutive acts of the charge-exchange in the outer heliosheath (OHS). The main findings can be …

The Kepler Light Curve Of V344 Lyrae: Constraining The Thermal-Viscous Limit Cycle Instability, John K. Cannizzo, Martin D. Still, Steve B. Howell, Matt A. Wood, Alan P. Smale

Aerospace, Physics, and Space Science Faculty Publications

We present time-dependent modeling based on the accretion disk limit cycle model for a 270 d light curve of the short-period SU UMa-type dwarf nova V344 Lyr taken by Kepler. The unprecedented precision and cadence (1 minute) far surpass that generally available for long-term light curves. The data encompass two superoutbursts and 17 normal (i.e., short) outbursts. The main decay of the superoutbursts is nearly perfectly exponential, decaying at a rate ~12 d mag−1, while the much more rapid decays of the normal outbursts exhibit a faster-than-exponential shape. Our modeling using the basic accretion disk limit cycle can produce the …

Precision Frequency Measurements With Interferometric Weak Values, David J. Starling, P. Ben Dixon, Andrew N. Jordan, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

We demonstrate an experiment which utilizes a Sagnac interferometer to measure a change in optical frequency of 129 ± 7 kHz/√Hz with only 2 mW of continuous-wave, single-mode input power. We describe the measurement of a weak value and show how even higher-frequency sensitivities may be obtained over a bandwidth of several nanometers. This technique has many possible applications, such as precision relative frequency measurements and laser locking without the use of atomic lines.

A Landscape Assessment Study Of The South Gozo Fault Area, Mariella Xuereb

Masters Theses, 2010-2019

The South Gozo Fault region features a heterogeneous landscape which extends from Ras il-Qala on the east, to „Mgarr ix-Xini‟ on the south-eastern littoral. In recent decades, parts of this region have experienced substantial levels of development while others remain untouched. This study seeks to explore the impact of existing and proposed development projects on the character and value of the South Gozo Fault landscape. A landscape character assessment, together with an assessment of the value of the landscape will be conducted, with the aim of analyzing the present character and value of the landscape, and comparing this with the …

A Preliminary Assessment Of The Long-Term Prospects For Offshore Wind Farms In Maltese Territorial Waters, Dane Orion Zammit

Masters Theses, 2010-2019

Almost all of Malta’s current interest in offshore wind development is focused on the development of an offshore wind farm at Sikka L-Bajda in northwest Malta by 2020, to help the country reach its mandated 2020 RES target. The offshore wind industry is rapidly gaining momentum, with larger projects in deeper waters further offshore being commissioned every year. Countries like Germany and the United Kingdom have actively constructed, or are planning to construct, offshore wind farms at transitional water depths before 2020. The offshore wind energy market has historically been restricted to the North Sea, the Baltic Sea and the …