Physical Sciences and Mathematics Commons^™

Lyapunov Exponents For Small Aspect Ratio Rayleigh-Benard Convection, Janet Scheel, M. Cross

Janet D. Scheel

Leading order Lyapunov exponents and their corresponding eigenvectors have been computed numerically for small aspect ratio, three-dimensional Rayleigh-Benard convection cells with no-slip boundary conditions. The parameters are the same as those used by Ahlers and Behringer [Phys. Rev. Lett. 40, 712 (1978)] and Gollub and Benson [J. Fluid Mech. 100, 449 (1980)] in their work on a periodic time dependence in Rayleigh-Benard convection cells. Our work confirms that the dynamics in these cells truly are chaotic as defined by a positive Lyapunov exponent. The time evolution of the leading order Lyapunov eigenvector in the chaotic regime will also be discussed. …

Electrostatic Assembly Of A Redox Catalysis System For Detection Of Glutamate, Alice Harper, Mark Anderson

Mark R. Anderson

Interfacial assemblies capable of determining glutamate by redox catalysis are prepared by electrostatic assembly of alternating layers of ferrocene poly(allylamine) polymer and glutamate oxidase on a gold electrode. Deposition of the polymer was confirmed in cyclic voltammetry measurements by the presence of a surface wave corresponding to the oxidation of the ferrocene group. In the presence of glutamate in the adjacent electrolyte solution, the current increases and approaches a pseudosteady state, consistent with redox catalysis. Electrodes modified with glutamate oxidase had a linear response to glutamate up to 0.0045 M with sensitivity of 20 μA/cm2 and a limit of detection …

Climate Change And Late Pliocene Acceleration Of Erosion In The Himalaya, Katharine Huntington, Ann Blythe, Kip Hodges

Ann Blythe

Studies of active mountain ranges suggest that atmospheric and geodynamic processes may be strongly coupled through erosion — a hypothesis that has led to a debate over the relative importance of climate and far-field tectonic forcing in influencing erosion. We addressed this debate by developing the detailed long-term erosional history of a transect in the central Annapurna Range of Nepal for comparison with the climate and tectonic forcing histories of the region. Patterns of apatite fission-track and muscovite 40Ar/39Ar apparent ages with elevation indicate a five-fold increase in apparent erosion rate between 2.5 and 0.9 Ma ago. The time frame …

Nano And Microscale Adhesion Energy Measurement For Au-Au Contacts In Microswitch Structures, Nima Rahbar, Zong Zong, Yifang Cao, Wole Soboyejo

Nima Rahbar

This paper presents a study of adhesion energies that are relevant to Au–Au microswitch contacts at the nano- and micronscales. Adhesionmeasurements are obtained from cantilevered Aumicroelectromechanical system(MEMS)microswitch structures with varying lengths. Scanning electron microscopymeasurements of the microbeam profiles are combined with fracture mechanics model for the estimation of the adhesion energy. Adhesion contact and pull-off experiments are combined with theoretical models for the extraction of adhesion energies associated with Au-coated atomic force microscopy tips and Aumicroswitch substrates. Finite element method simulation was also performed to account for crack-tip shielding contributions from asperities in contact between Au–Au microscale cantilevered MEMS structure. …

Physical And Structural Basis For The Strong Interactions Of The -Impy- Central Pairing Motif In The Polyamide F-Impyim, K. Buchmueller, S. Bailey, D. Matthews, Z. Taherbhai, J. Register, Z. Davis, Chrystal Bruce, C. O'Hare, J. Hartley, M. Lee

Chrystal D. Bruce

The polyamide f-ImPyIm has a higher affinity for its cognate DNA than either the parent analogue, distamycin A (10-fold), or the structural isomer, f-PyImIm (250-fold), has for its respective cognate DNA sequence. These findings have led to the formulation of a two-letter polyamide “language” in which the -ImPy- central pairings associate more strongly with Watson−Crick DNA than -PyPy-, -PyIm-, and -ImIm-. Herein, we further characterize f-ImPyIm and f-PyImIm, and we report thermodynamic and structural differences between -ImPy- (f-ImPyIm) and -PyIm- (f-PyImIm) central pairings. DNase I footprinting studies confirmed that f-ImPyIm is a stronger binder than distamycin A and f-PyImIm and …

Incorporating Support For Event Algebra In Relational Stream Systems, Vijay Dialani, Inderpal Narang

Vijay Dialani

Data stream management systems make prominent use of a subset of relational algebra for describing continuous queries. The phenomenon has highlighted the wide spread use of declarative interface for stream data manipulation. As relational algebra is set oriented while the data streams are essentially sequences of data, there exist some cases where the use of relational algebra to describe processing in a data stream management system is counter productive. Supporting event algebraic operations on stream systems represents one such case. We have developed a combination of sequence algebra and relational algebra that is capable of supporting event algebra. Our alternative …

Formation And Stabilization Of Persistent Free Radicals, Barry Dellinger, Slawomir Lomnicki, Lavrent Khachatryan, Zofia Maskos, Randall W. Hall, Julien Adounkpe, Cheri Mcferrin, Hieu Truong

Randall W. Hall

Nanostructured Bi2se3 Films And Their Thermoelectric Transport Properties., Xiaofeng Qiu, Leah Austin, Philip Muscarella, Jeffrey Dyck, Clemens Burda

Jeffrey Dyck

No abstract provided.

Precision And Accuracy Of Thermal Calibration Of Atomic Force Microscopy Cantilevers, Nancy Burnham, G Matei, E Thoreson, J Pratt, D Newell

Nancy A. Burnham

To have confidence in force measurements made with atomic force microscopes(AFMs), the spring constant of the AFM cantilevers should be known with good precision and accuracy, a topic not yet thoroughly treated in the literature. In this study, we compared the stiffnesses of uncoated tipless uniform rectangular silicon cantilevers among thermal, loading, and geometric calibration methods; loading was done against an artifact from the National Institute of Standards and Technology (NIST). The artifact was calibrated at NIST using forces that were traceable to the International System of units. The precision and accuracy of the thermal method were found to be …

Breathless: Schools, Air Toxics, And Environmental Justice In California, Manuel Pastor, Rachel Morello-Frosch, James Sadd

James Sadd

The exposure of children to environmental disamenities has emerged as a key policy concern in recent years, with some analysts and activists suggesting that minority children are disproportionately impacted. Utilizing a dataset that combines air toxics at the census tract level with school-based demographic and other information, this article indicates disparate exposures for students of color in California schools and suggests that there may be negative impacts on one measure of academic performance, even after controlling for other factors usually associated with test scores. Policy implications include a special focus on school remediation and strengthening overall efforts to reduce emissions …

Characterization Of The Domain Chaos Convection State By The Largest Lyapunov Exponent, Janet Scheel, A. Jayaraman, H. Greenside, P. Fischer

Janet D. Scheel

Using numerical integrations of the Boussinesq equations in rotating cylindrical domains with realistic boundary conditions, we have computed the value of the largest Lyapunov exponent λ1 for a variety of aspect ratios and driving strengths. We study in particular the domain chaos state, which bifurcates supercritically from the conducting fluid state and involves extended propagating fronts as well as point defects. We compare our results with those from Egolf et al., [Nature 404, 733 (2000)], who suggested that the value of λ1 for the spiral defect chaos state of a convecting fluid was determined primarily by bursts of instability arising …

Structure And Enhanced Reactivity Rates Of The D 5 H Sc3n@ C80 And Lu3n@ C80 Metallofullerene Isomers: The Importance Of The Pyracylene Motif, Ting Cai, Liaosa Xu, Mark Anderson, Zhongxin Ge, Tianming Zuo, Xuelei Wang, Marilyn Olmstead, Alan Balch, Harry Gibson, Harry Dorn

Mark R. Anderson

In this paper we report enhanced reactivity of the D5h isomers in comparison with the more common Ih isomers of Sc3N@C80 and Lu3N@C80 toward Diels−Alder and 1,3-dipolar tritylazomethine ylide cycloaddition reactions. Also, the structure of the D5h isomer of Sc3N@C80 has been determined through single-crystal X-ray diffraction on D5h-Sc3N@C80·Ni(OEP)·2benzene (OEP = octaethylporphyrin). The Sc3N portion of D5h-Sc3N@C80 is strictly planar, but the plane of these four atoms is tipped out of the noncrystallographic, horizontal mirror plane of the fullerene by 30°. The combination of short bond length and high degree of pyramidization for the central carbon atoms of the pyracylene …

Substantial Pressure Effect On The Resistivity And Curie Temperature For The Diluted Magnetic Semiconductor Sb2–X Vx Te3., Jeffrey Dyck, K. Ahilan, M. Aronson, C. Uher, P. Lošťák

Jeffrey Dyck

The influence of hydrostatic pressure on the electrical resistivity ρ and ferromagnetic transition temperature T C of bulk, single crystal Sb1–x Vx Te3 with x = 0.03 is presented. Pressure strongly suppresses ρ at all temperatures, with an overall decrease of about 35% at 1.6 GPa. The peak in ρ , a signature of T C, moves to lower temperature with increasing pressure. An overall suppression of T C near 40% at 1.6 GPa is observed. The results are discussed within the context of a carrier-mediated ferromagnetic exchange interaction.

Bayesian Wavelet Estimation Of Partially Linear Models, Leming Qu

Leming Qu

A Bayesian wavelet approach is presented for estimating a partially linear model (PLM). A PLM consists of a linear part and a nonparametric component. The nonparametric component is represented with a wavelet series where the wavelet coefficients have assumed prior distributions. The prior for each coefficient consists of a mixture of a normal distribution and a point mass at 0. The linear parameters are assumed to have a normal prior. The hyperparameters are estimated by the marginal maximum likelihood estimator using the direct maximization. The model selection and model averaging methods give different estimates of the model parameters. MCMC computation …

Effect Of The Centrifugal Force On Domain Chaos In Rayleigh-Bénard Convection, Janet Scheel, N. Becker, M. Cross, G. Ahlers

Janet D. Scheel

Experiments and simulations from a variety of sample sizes indicated that the centrifugal force significantly affects the domain-chaos state observed in rotating Rayleigh-Bénard convection-patterns. In a large-aspect-ratio sample, we observed a hybrid state consisting of domain chaos close to the sample center, surrounded by an annulus of nearly stationary nearly radial rolls populated by occasional defects reminiscent of undulation chaos. Although the Coriolis force is responsible for domain chaos, by comparing experiment and simulation we show that the centrifugal force is responsible for the radial rolls. Furthermore, simulations of the Boussinesq equations for smaller aspect ratios neglecting the centrifugal force …

A New Basis For The Solution Of The One-Dimensional Transport Equation, Stephen Brill

Stephen H. Brill

We present a family of functions that satisfy the one-dimensional convection-diffusion equation. This partial differential equation is widely used in the sciences and engineering, including to model the transport of contaminant dissolved in groundwater. Combinations of these functions are formed to satisfy boundary and initial conditions. The result is an inexpensive and highly accurate solution methodology.

Substrate Rigidity Regulates The Formation And Maintenance Of Tissues, Nancy Burnham, Wei-Hui Guo, Margo Frey, Yu-Li Wang

Nancy A. Burnham

The ability of cells to form tissues represents one of the most fundamental issues in biology. However, it is unclear what triggers cells to adhere to one another in tissues and to migrate once a piece of tissue is planted on culture surfaces. Using substrates of identical chemical composition but different flexibility, we show that this process is controlled by substrate rigidity: on stiff substrates, cells migrate away from one another and spread on surfaces, whereas on soft substrates they merge to form tissue-like structures. Similar behavior was observed not only with fibroblastic and epithelial cell lines but also explants …

Climatic Forcing Of Erosion, Landscape, And Tectonics In The Bhutan Himalayas, Djordje Grujic, Isabelle Coutand, Bodo Bookhagen, Stéphane Bonnet, Ann Blythe, Chris Duncan

Ann Blythe

A fundamental objective in studies of climate-erosion-tectonics coupling is to document convincing correlation between observable indicators of these processes on the scale of a mountain range. The eastern Himalayas are a unique range to quantify the contribution of tectonics and climate to long-term erosion rates, because uniform and steady tectonics have persisted for several million years, while monsoonal precipitation patterns have varied in space and time. Specifically, the rise of the Shillong plateau, the only orographic barrier in the Himalayan foreland, has reduced the mean annual precipitation downwind in the eastern Bhutan Himalaya at the Miocene-Pliocene transition. Apatite fission-track (AFT) …

Computer Skills, Gender, And Technostress In Higher Education, Sonya Shepherd

Sonya S. Gaither

The creation of computer software and hardware, telecommunications, databases, and the Internet has affected society as a whole, and particularly higher education by giving people new productivity options and changing the way they work (Hulbert, 1998). In the so-called “information age” the increasing use of technology has become the driving force in the way people work, learn, and play (Drake, 2000). As this force evolves, the people using technology change also (Nelson, 1990). Adapting to technology is not simple. Some people tend to embrace change while others resist change (Wolski & Jackson, 1999). Before making a decision on whether to …

A History Of Political Experience, Leslie Marsh

Leslie Marsh

This book survives superficial but fails deeper scrutiny. A facile, undiscerning criticism of Lectures in the History of Political Thought (LHPT) is that on Oakeshott’s own account these are lectures on a non-subject: ‘I cannot detect anything which could properly correspond to the expression “the history of political thought”’ (p. 32). This is an entirely typical Oakeshottian swipe – elegant and oblique – at the title of the lecture course he inherited from Harold Laski. If title and quotation sit awkwardly we should remember that Oakeshott never prepared the text for publication – a fortiori he did not prepare it …

Collaborative Games: Lessons Learned From Board Games, Jose Zagal, Rick Jochen, Hsi Idris

Jose P Zagal

Collaborative mechanisms are starting to become prominent in computer games, like massively multiplayer online games (MMOGs); however, by their nature, these games are difficult to investigate. Game play is often complex and the underlying mechanisms are frequently opaque. In contrast, board games are simple. Their game play is fairly constrained and their core mechanisms are transparent enough to analyze. In this article, the authors seek to understand collaborative games. Because of their simplicity, they focus on board games. The authors present an analysis of collaborative games. In particular, they focus on Reiner Knizia’s LORDOFTHERINGS, considered by many to be the …

High-Resolution Raman Spectra With Femtosecond Pulses: An Example Of Combined Time- And Frequency-Domain Spectroscopy, Sukhendu Nath, Diana Urbanek, Sean Kern, Mark Berg

Sean J. Kern

Frequency-domain spectroscopy requires long pulses, whereas time-domain spectroscopy requires short pulses. This Letter demonstrates both theoretically and experimentally that simultaneous detection in frequency and time generates well-resolved spectra using intermediate-length pulses. In the case of coherent Raman spectroscopy, typical femtosecond pulses lie between the time and frequency domains. To demonstrate this method, a high-resolution Raman spectrum of nitrobenzene is obtained from 60 fs pulses. Phase control, pulse shaping, or pulses of widely differing duration are not required.

An Undular Bore Solution For The Higher-Order Korteweg-De Vries Equation, Tim Marchant

Tim Marchant

Undular bores describe the evolution and smoothing out of an initial step in mean height and are frequently observed in both oceanographic and meteorological applications. The undular bore solution for the higher-order Korteweg-de Vries (KdV) equation is derived, using an asymptotic transformation which relates the KdV equation and its higher-order counterpart. The higher-order KdV equation considered includes all possible third-order correction terms (where the KdV equation retains second-order terms). The asymptotic transformation is then applied to the KdV undular bore solution to obtain the higher-order undular bore. Examples of higher-order undular bores, describing both surface and internal waves, are presented. …

Solitary Wave Interaction And Evolution For A Higher-Order Hirota Equation, Tim Marchant

Tim Marchant

Solitary wave interaction and evolution for a higher-order Hirota equation is examined. The higher-order Hirota equation is asymptotically transformed to a higher-order member of the NLS hierarchy of integrable equations, if the higher-order coefficients satisfy a certain algebraic relationship. The transformation is used to derive higher-order one- and two-soliton solutions. It is shown that the interaction is asymptotically elastic and the higher-order corrections to the coordinate and phase shifts are derived. For the higher-order Hirota equation resonance occurs between the solitary waves and linear radiation, so soliton perturbation theory is used to determine the details of the evolving wave and …

Evidence For Monazite Growth At ~1.6 Ga And ~1.4 Ga In Proterozoic Migmatites Of The Santa Fe Range, North-Central New Mexico, Dan Heuer, Christopher Daniel

Dan Heuer

Supracrustal Proterozoic migmatites exposed in the Aspen Basin area of the Santa Fe Range represent the northernmost exposure of the Mazatzal (~1.65 Ga) crustal province. Two migmatite samples (plag-bt-ms-qtz-hem±grt) yield preliminary in-situ electron microprobe U-Th-total Pb ages from monazite that are ~1.4 Ga; however, 1 grain yields a core age of ~1.6 Ga.

Monazite are generally aligned subparallel to a regional moderately, south-dipping foliation (S1), indicating monazite growth was pre- or synkinematic. X-ray mapping of monazite shows variable U, Th, Pb, Y, and Ce zoning, interpreted to reflect three periods of monazite growth. Xenotime are relatively unzoned in most elements, …

Monazite Thermochronometry In Migmatites From North-Central New Mexico: Contact Metamorphism Or A Regional Mid-Crustal Melt-Rich Layer?, Dan Heuer, Christopher Daniel, Joseph Pyle

Dan Heuer

Monazite thermochronometry demonstrates that Proterozoic migmatites exposed in the central Santa Fe range and the Rincon range of north-central New Mexico preserve high-temperature monazite that crystallized near 1.4 Ga. No 1.4 Ga plutons are exposed in the Rincon range; however, undated plutons are present in the Santa Fe Range and a contact metamorphic setting is possible. Alternatively, partial melting in these two areas may represent a regional, mid-crustal, melt-rich layer.

Subhedral monazite in both areas are commonly aligned subparallel with the dominant regional foliation. Monazite from the central Santa Fe range show three distinct compositional domains. Relatively high-Y cores yield …

Modelling A Wool Scour Bowl, Tim Marchant

Tim Marchant

Wool scouring is the process of washing dirty wool after shearing. Our model simulates, using the advection-diffusion equation, the movement of contaminants within a scour bowl. The effects of varying the important parameters are investigated. Interesting, but simple, relationships are found which give insight into the dynamics of a scour bowl.

Jet-Based Methods To Print Living Cells, Bradley Ringeisen, Christina Othon, Jason Barron, H Young, Barry Spargo

Christina M Othon

Cell printing has been popularized over the past few years as a revolutionary advance in tissue engineering has potentially enabled heterogeneous 3-D scaffolds to be built cell-by-cell. This review article summarizes the state-of-the-art cell printing techniques that utilize fluid jetting phenomena to deposit 2- and 3-D patterns of living eukaryotic cells. There are four distinct categories of jetbased approaches to printing cells. Laser guidance direct write (LG DW) was the first reported technique to print viable cells by forming patterns of embryonic-chick spinal-cord cells on a glass slide (1999). Shortly after this, modified laser-induced forward transfer techniques (LIFT) and modified …

Projects That Assist With Content In A Traditional Organic Chemistry Course, John Esteb, John Magers, Luanne Mcnulty, Anne Wilson

John Esteb

Projects that engage undergraduate students in content-based courses, such as organic chemistry, must relate to the material and provide useful tools for the divergent needs of the students. There are few examples of these types of projects in the literature. Herein, we describe two projects, the reaction notebook and the end-of-semester synthesis activity. Each project is designed to stimulate student ownership of the material and leads to engagement with the content of the course.

Note: Link is to the article in a subscription database available to users affiliated with Butler University. Appropriate login information will be required for access. Users …

Kinetic Deuterium Isotope Effects On The Reactions Of 2-(4-Methoxyphenyl)Oxirane In Water Solutions, Ram Mohan, Victoria Ukachukwu, Dale Whalen

Ram S. Mohan

The rates of reaction of 2-(4-methoxyphenyl)oxirane (4-methoxystyrene oxide), trans-3-deutereo-2-(4-methoxyphenyl)oxirane and 3,3-dideutereo-2-(4-methoxyphenyl)oxirane in water solutions were measured as functions of pH. Kinetic deuterium isotope effects for the reactions of the mono- and di-deuterated (4-methoxyphenyl)oxiranes were determined for both the acid-catalyzed hydrolysis to diols and the pH-independent reactions leading mostly to rearranged aldehyde and involving a 1,2-hydrogen migration. The inverse kinetic deuterium isotopes for acid-catalyzed hydrolyses of the deuterated (4-methoxyphenyl)oxiranes to diols are consistent with rate-limiting epoxide ring opening. The magnitudes of the normal kinetic deuterium isotope effects on the pH-independent reactions of deuterated 4-methoxyphenyloxiranes are significantly smaller than the deuterium …