Digital Commons Network^™

Tidal Asymmetry And Residual Circulation Over Linear Sandbanks And Their Implication On Sediment Transport: A Process-Oriented Numerical Study, Rosario Sanay, George Voulgaris, John C. Warner

Faculty Publications

A series of process-oriented numerical simulations is carried out in order to evaluate the relative role of locally generated residual flow and overtides on net sediment transport over linear sandbanks. The idealized bathymetry and forcing are similar to those present in the Norfolk Sandbanks, North Sea. The importance of bottom drag parameterization and bank orientation with respect to the ambient flow is examined in terms of residual flow and overtide generation, and subsequent sediment transport implications are discussed. The results show that although the magnitudes of residual flow and overtides are sensitive to bottom roughness parameterization and bank orientation, the …

Tomography Of The Darcy Velocity From Self-Potential Measurements, A. Jardani, A. Revil, A. Bolève, A. Crespy, J.-P. Dupont, W. Barrash, Bwalya Malama

Natural Resources Management and Environmental Sciences

An algorithm is developed to interpret self-potential (SP) data in terms of distribution of Darcy velocity of the ground water. The model is based on the proportionality existing between the streaming current density and the Darcy velocity. Because the inverse problem of current density determination from SP data is underdetermined, we use Tikhonov regularization with a smoothness constraint based on the differential Laplacian operator and a prior model. The regularization parameter is determined by the L-shape method. The distribution of the Darcy velocity depends on the localization and number of non-polarizing electrodes and information relative to the distribution of the …

Target Space Duality With Dilaton And Tachyon Field, Blazej Ruszczycki

Open Access Dissertations

We study the target space duality of classical two dimensional sigma models. The models with dilaton and tachyon field are analyzed. As a motivating example the historical electric-magnetic duality is presented. We review the construction of the duality transformation and the integrability conditions for the nonlinear sigma models with target spaces described by general metrics and antisymmetric two-forms. We generalize the formalism for the models whose actions contain the dilaton and tachyon field. For the dilaton field case it is required that the duality is a property solely of the target manifolds, independent of the world-sheet geometry. For both cases …

A Quantitative Description Of The Interaction Of Enhancement And Depression Of Transmitter Release At The Neuromuscular Junction, Alice M. Holohean

Open Access Dissertations

Synaptic transmission alters the strength of the postsynaptic potential, through a process called short-term synaptic plasticity (STP). In this study, endplate potentials (EPPs) from the frog neuromuscular junction were used to resolve and quantify the presynaptic components involved in enhancement and depression of transmitter release during repetitive stimulation under normal quantal release conditions (2 mM Ca2+, 1mM Mg2+). During trains of stimulation given between 10 - 200 Hz, the amplitude of the EPPs first increased then decreased; a maximum increase of 77% was produced after 2-4 stimuli. EPP amplitudes began to increase at ~ 20 Hz, were maximal at ~ …

Sound Transmission Through A Fluctuating Ocean: A Modal Approach, Ilya A. Udovydchenkov

Open Access Dissertations

Sound transmission through a fluctuating deep ocean environment is considered. It is assumed that the environment consists of a range-independent background, on which a small-scale perturbation, due for example to internal waves, is superimposed. The modal description of underwater sound propagation is used extensively. The temporal spread of modal group arrivals in weakly range-dependent deep ocean environments is considered. The phrase "modal group arrival" refers to the contribution to a transient wavefield corresponding to a fixed mode number. It is shown that there are three contributions to modal group time spreads which combine approximately in quadrature. These are the reciprocal …

2007 Winter Boise State University Commencement Program

Commencement Programs

No abstract provided.

Tomography Of The Darcy Velocity From Self-Potential Measurements, A. Jardani, A. Revil, A. Bolève, A. Crespy, J.-P. Dupont, Warren Barrash, Bwalya Malama

CGISS Publications and Presentations

An algorithm is developed to interpret self-potential (SP) data in terms of distribution of Darcy velocity of the ground water. The model is based on the proportionality existing between the streaming current density and the Darcy velocity. Because the inverse problem of current density determination from SP data is underdetermined, we use Tikhonov regularization with a smoothness constraint based on the differential Laplacian operator and a prior model. The regularization parameter is determined by the L-shape method. The distribution of the Darcy velocity depends on the localization and number of non-polarizing electrodes and information relative to the distribution of the …

University Of Nebraska At Omaha, December Commencement 2007, University Of Nebraska At Omaha

Commencement Programs

No abstract provided.

Incorporating Grain Size Effects In Taylor Crystal Plasticity, Bradley S. Fromm

Theses and Dissertations

A method to incorporate grain size effects into crystal plasticity is presented. The classical Hall-Petch equation inaccurately predicts the macroscopic yield strength for materials with non-equiaxed grains or materials that contain unequal grain size distributions. These deficiencies can be overcome by incorporating both grain size and orientation characteristics into crystal plasticity theory. Homogenization relationships based on a viscoplastic Taylor-like approach are introduced along with a new function, the grain size and orientation distribution function (GSODF). Estimates of the GSODF for high purity α-titanium are recovered through orientation imaging microscopy coupled with the chord length distribution. A comparison between the new …

Observation Of P-Wave Threshold Behavior In Electron Attachment To F2 Molecules, M. Braun, M.-W. Ruf, Ilya I. Fabrikant, H. Hotop

Ilya Fabrikant Publications

Using the high resolution laser photoelectron attachment method, we demonstrate that the cross section for F^- formation due to electron capture by F² (X¹Σ_g⁺) molecules at very low energies exhibits p-wave threshold behavior. This finding confirms the theoretical expectation that low-energy attachment to F₂ proceeds through the F₂^-(² Σ_u⁺) p-wave shape resonance in contrast with previous experimental claims for s-wave threshold behavior.

Measurement Of The Pp̅ → Wz + X Cross Section At √S =1.96 Tev And Limits On Wwz Trilinear Gauge Couplings, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

We present measurements of the process pp̅ → WZ + X → ℓ′νℓℓ&#; at √s = 1.96 TeV, where ℓ and ℓ′ are electrons or muons. Using 1 fb^-1 of data from the D0 experiment, we observe 13 candidates with an expected background of 4.5 ± 0.6 events and measure a cross section σ(WZ) = 2.7_-1.3^+1.7 pb. From the number of observed events and the Z boson transverse momentum distribution, we limit the trilinear WWZ gauge couplings to -0.17 ≤ λ_Z ≤ 0.21(Δκ_Z= 0) at the 95% C.L. for a form …

American Index Put Options Early Exercise Premium Estimation, Ako Doffou

WCBT Faculty Publications

"This paper examines empirically the value of early exercise by testing the ability of two American put valuation models to predict the early exercise premium for the S&P 100 American put options. An accuracy test and a quality test are performed on (1) the MacMillan (1986) & Barone-Adesi and Whaley (1987) model, and (2) the Carr, Jarrow and Myneni(1992) model. The test results show that early exercise premium is significant regardless of moneyness. Moreover, consistent with the theory, the value of early exercise is significantly negatively related to moneyness and interest rates and significantly positively related to time to maturity …

Biogeochemical Evolution Of Cryoconite Holes On Canada Glacier, Taylor Valley, Antarctica, Elizabeth A. Bagshaw, Martyn Tranter, Andrew G. Fountain, Kathleen A. Welch, Hassan J. Basagic, W. Berry Lyons

Geography Faculty Publications and Presentations

The cryoconite holes of the McMurdo Dry Valleys are simple, closed biogeochemical systems involving water, ice, mineral and organic debris, which serve as ecosystems for consortia of microorganisms. This study is the first to document the seasonal and annual chemical evolution of solutes in cryoconite holes. Samples of glacier ice, frozen cryoconite holes and those containing water were collected during the austral summer of 2005–2006. The isolation age was calculated from the excess Cl‾ in the holes, and varied from 0 to 5 years (a), consistent with the last hot summer when the cryoconite holes were open to the atmosphere. …

Review Of The Triumph Of Numbers By I. B. Cohen, H L. Vacher

Numeracy

I. Bernard Cohen, The Triumph of Numbers: How Counting Shaped Modern Life. (New York: W.W. Norton & Company, 2005). 209 pp. $24.95 (USA). ISBN 0-393-05769-0.

The premier historian of science ends his career telling how the world has become awash in numbers—“how numbers entered the conduct of life and of government, the understanding of nature, and the analysis of societies.” The stories begin with Kepler and end with Florence Nightingale. In between, major players include Galileo, Harvey, Leeuwenhoek, and Halley; Graunt and Petty; Jefferson and Franklin; Lavoisier, Sinclair, Pinel and Louis; Guerry and Quetelet. The book tells of the spread …

Birds–Dead And Deadly: Why Numeracy Needs To Address Social Construction, Joel Best

Numeracy

Sociologists use the term social construction to refer to the processes by which people assign meaning to their world. This paper argues that numeracy education needs to address social construction. In particular, thinking critically about the statistics the news media report regarding social issues requires understanding the competitive nature of the social problems marketplace, and the social forces that allow questionable numbers to receive widespread public attention. Such critiques must incorporate more than assessing how the numbers were calculated; they must consider the social construction of particular statistics. Two recent examples—claims about the number of birds killed flying into windows, …

Development Of Case Stories By Interviewing Students About Their Critical Moments In Science, Math, And Engineering Classes, Vicki V. May, Thomas H. Luxon, Kathy Weaver, Rachel Esselstein, Cynthia Char

Numeracy

Dartmouth’s Critical Moments project is designed to promote discussions among faculty and graduate students about the retention of students, particularly women and minorities, in science, math, and engineering (SME) disciplines. The first phase of the ongoing project has been the development of four case stories, which are fictionalized composites drawn from surveys and interviews of real Dartmouth students. The surveyed population was 125 students in general chemistry. Of the 77 who agreed to be interviewed, 61 reported having experienced a critical moment – i.e., a positive or negative event or time that had a significant impact on the student’s academic …

Teachers Talk: Pressure Points In The K-8 Mathematics Curriculum, Kim Rheinlander, Dorothy Wallace, Wells Morrison, Daniel Ansari, Donna Coch, B. Venus Williams

Numeracy

Forty K-8 teachers participated in small, in-depth, facilitated discussions about "pressure points" in the curriculum. We define a pressure point as a topic, skill, or concept that is crucial to future mathematics learning but which many or most students do not master to the extent expected at a given grade level. They are issues that persist from one grade level to the next; eventually they impair the ability of students to succeed in technical disciplines. The teachers identified a number of pressure points; we focus on an understanding of place value and "reasonableness" of answer as two examples that were …

Scientifically Based Research In Quantitative Literacy: Guidelines For Building A Knowledge Base, Richard L. Scheaffer

Numeracy

Research in quantitative literacy (QL) is in its infancy, so now is the time to begin a regimen for healthy growth into adulthood. As a new discipline still defining itself, QL has the opportunity to build a sound infrastructure for accumulating a solid body of interconnected research that will serve the discipline well in years to come. To that end, much can be learned from recent studies of the weaknesses of mathematics education research and recommendations on how to overcome them. Mathematics education lacks a strong research foundation, one that is scientific, cumulative, interconnected, and intertwined with teaching practice. These …

Evolution Of Numeracy And The National Numeracy Network, Bernard L. Madison, Lynn Arthur Steen

Numeracy

The National Numeracy Network grew from heightened awareness of the complex and sophisticated nature of quantitative literacy and the resulting need for interdisciplinary attention to education for quantitative literacy in schools and colleges. This complexity and sophistication applies especially to the US where it is fueled by an agile economy and the needs of a democratic society. This paper describes the environment surrounding the National Numeracy Network’s establishment, some of its activities, and some complementary and synergistic actions by other professional societies. The paper concludes with a sample of quantitative literacy programs in colleges and universities

The Scope Of Numeracy, H L. Vacher, Dorothy Wallace

Numeracy

No abstract provided.

Lagrangian Coherent Structures And Transport In Two-Dimensional Incompressible Flows With Oceanographic And Atmospheric Applications, Irina I. Rypina

Open Access Dissertations

The Lagrangian dynamics of two-dimensional incompressible fluid flows is considered, with emphasis on transport processes in atmospheric and oceanic flows. The dynamical-systems-based approach is adopted; the Lagrangian motion in such systems is studied with the aid of Kolmogorov-Arnold-Moser (KAM) theory, and results relating to stable and unstable manifolds and lobe dynamics. Some nontrivial extensions of well-known results are discussed, and some extensions of the theory are developed. In problems for which the flow field consists of a steady background on which a time-dependent perturbation is superimposed, it is shown that transport barriers arise naturally and play a critical role in …

An Ab Initio Study Of The Structures, Vibrational Spectra, And Energetics Of Alshx (X = –1, 0, +1), Sujata Guha, Joseph S. Francisco

Chemistry Faculty Research

The ground state of aluminum hydrosulfide, AlSHX (where X = − 1,0, + 1), has been examined using high-level ab initio electronic structure calculations at the CCSD(T) level with an augmented correlation-consistent basis set. The geometries have been optimized up through the aug-cc-pV5Z level and vibrational frequencies calculated using the aug-cc-pV5Z basis set. The energetic properties of AlSH are also examined. The adiabatic ionization potential and electron affinity of AlSH are calculated to be 198.5 and 7.7 kcal mol−1, respectively. Dissociation of AlSH into AlS + H will require 78.2 kcal mol−1 of energy, and the Al-S bond energy is …

Ultrashort Intense-Field Optical Vortices Produced With Laser-Etched Mirrors, James Strohaber, Timothy D. Scarborough, Cornelis J. Uiterwaal

C.J.G.J. Uiterwaal Publications

We introduce a simple and practical method to create ultrashort intense optical vortices for applications involving high-intensity lasers. Our method utilizes femtosecond laser pulses to laser etch grating lines into laser-quality gold mirrors. These grating lines holographically encode an optical vortex. We derive mathematical equations for each individual grating line to be etched, for any desired (integer) topological charge. We investigate the smoothness of the etched grooves. We show that they are smooth enough to produce optical vortices with an intensity that is only a few percent lower than in the ideal case. We demonstrate that the etched gratings can …

Clemson Commencement Program, December 2007, Clemson University

Clemson Commencement Programs

No abstract provided.

Automated Refinement And Augmentation Of Web Service Description Files, Marc Fisher Ii, Sebastian Elbaum, Gregg Rothermel

School of Computing: Technical Reports

Web Service Description Language (WSDL) is being increasingly used to specify web service interfaces. Specifications of this type, however, are often incomplete or imprecise. For example, cursory examination of the WSDL file for Amazon’s E-Commerce Web Service reveals that it often uses a less specific type where a more specific type is applicable, or declares that elements could be missing where other documentation indicates that they are required. Further, specifications reflecting the temporal relationships between operations are completely missing, which is not surprising since they are not supported by the current WSDL standard. These problems in WSDL specifications can cause …

Preparation Of Divalent And Trivalent Antigens For Immunogical Studies On Degranulation Of Mast Cells And Preparation Of Ceragenins For Antiviral Studies Against Vaccinia Virus., Dianliang Geng

Theses and Dissertations

CHAPTER 1

Aggregation of receptors for IgE (Fc RI) causes mast cells and basophils to release preformed contents of granules, including histamine and a variety of enzymes. This process, called degranulation plays a central role in allergic reactions. Methods to study this process are to create multivalent ligands which can interact with the receptors and, in turn, lead to aggregation of the receptors. We prepared a series of fluorophore-labeled divalent and trivalent antigens to study the degranulation of mast cells. Trivalent antigens proved to be much better stimulators for degranulation of mast cells than divalent antigens. These results indicate that …

Holy Cross Magazine, Vol. 42 No. 1, Winter 2008, College Of The Holy Cross

Holy Cross Magazine

The Place For Athletics
At a time when college sports scandals abound and the Academy is rethinking the proper place for athletics within the world of higher education, HCM recently sponsored a forum on this complex and challenging subject. Read the transcript of this discussion and discover what the future might hold for Crusader sports.
Moderated by Clark V. Booth ’61
Photographs by Patrick O’Connor

Flashback: The Bard of Linden Lane
Jesuit, College administrator and ardent booster for alma mater, Rev. Michael J. Earls of the Class of 1896 brought national attention to Holy Cross when he hosted G.K. Chesterton’s …

Evidence For A Population Of High-Redshift Submillimeter Galaxies From Interferometric Imaging, Joshua D. Younger, Giovanni G. Fazio, Jia Sheng Huang, Min S. Yun, Grant W. Wilson, Matthew L.N. Ashby, Mark A. Gurwell, Kamson Lai, Alison B. Peck, Glen R. Petitpas, David J. Wilner, Daisuke Iono, Kotaro Kohno, Ryohei Kawabe, David H. Hughes, Itziar Aretxaga, Tracy Webb, Alejo Martínez-Sansigre, Sungeun Kim, Kimberly S. Scott, Jason Austermann, Thushara Perera, James Lowenthal, Eva Schinnerer, Vernesa Smolčić

Astronomy: Faculty Publications

We have used the Submillimeter Array to image a flux-limited sample of seven submillimeter galaxies, selected by the AzTEC camera on the JCMT at 1.1 mm, in the COSMOS field at 890 μm with ∼2″ resolution. All of the sources - two radio-bright and five radio-dim - are detected as single point sources at high significance (>6 σ), with positions accurate to ∼0.2″ that enable counterpart identification at other wavelengths observed with similarly high angular resolution. All seven have IRAC counterparts, but only two have secure counterparts in deep HST ACS imaging. As compared to the two radio-bright sources …

Merged Ionization/Dissociation Fronts In Planetary Nebulae, William J. Henney, R. J. R. Williams, Gary J. Ferland, Gargi Shaw, C. R. O'Dell

Physics and Astronomy Faculty Publications

The hydrogen ionization and dissociation front around an ultraviolet radiation source should merge when the ratio of ionizing photon flux to gas density is sufficiently low and the spectrum is sufficiently hard. This regime is particularly relevant to the molecular knots that are commonly found in evolved planetary nebulae, such as the Helix Nebula, where traditional models of photodissociation regions have proved unable to explain the high observed luminosity in H₂ lines. In this paper we present results for the structure and steady state dynamics of such advection-dominated merged fronts, calculated using the Cloudy plasma/molecular physics code. We find …

Spatio-Temporal Associations Between Goes Aerosol Optical Depth Retrievals And Ground-Level Pm2.5, Christopher J. Paciorek, Yang Liu, Hortensia Moreno-Macias, Shobha Kondragunta

Harvard University Biostatistics Working Paper Series

We assess the strength of association between aerosol optical depth (AOD) retrievals from the GOES Aerosol/Smoke Product (GASP) and ground-level fine particulate matter (PM2.5) to assess AOD as a proxy for PM2.5 in the United States. GASP AOD is retrieved from a geostationary platform and therefore provides dense temporal coverage with half-hourly observations every day, in contrast to once per day snapshots from polar-orbiting satellites. However, GASP AOD is based on a less-sophisticated instrument and retrieval algorithm. We find that correlations between GASP AOD and PM2.5 over time at fixed locations are reasonably high, except in the winter and in …