Digital Commons Network^™

Characterization Of Two-Dimensional Finite-Aperture Wire Grid Polarizers By A Spectral-Domain Technique, Michael A. Jensen, Gregory P. Nordin

Faculty Publications

We investigate the transmission characteristics of perfectly conducting two-dimensional wire grid polarizers fabricated in finite and infinite apertures using a rigorous spectral-domain mode-matching method. Specifically, the transmission coefficient for both transverse-electric and transverse-magnetic polarizations, extinction ratio, and diffraction pattern are characterized for a wide variety of geometric and material parameters including aperture dimension, conducting wire fill factor, wire spacing, polarizer thickness, material dielectric constants, and incident wave arrival angle. The results indicate that the transmission behavior is largely insensitive to aperture dimension.

Timescale Stretch Parameterization Of Type Ia Supernova B-Band Light Curves, G. Goldhaber, D. E. Groom, A. Kim, G. Aldering, P. Astier, A. Conley, S. E. Deustua, R. Ellis, S. Fabbro, A. S. Fruchter, A. Goobar, I. Hook, M. Irwin, M. Kim, R. A. Knop, C. Lidman, R. Mcmahon, P. E. Nugent, R. Pain, N. Panagia, C. R. Pennypacker, S. Perlmutter, P. Ruiz-Lapuente, B. Schaefer, N. A. Walton, T. York

Faculty Publications

R-band intensity measurements along the light curve of Type Ia supernovae (SNe Ia) discovered by the Supernova Cosmology Project (SCP) are fitted in brightness to templates allowing a free parameter the time-axis width factor w ≡ s(1 + z). The data points are then individually aligned in the time axis, normalized, and K-corrected back to the rest frame, after which the nearly 1300 normalized intensity measurements are found to lie on a well-determined common rest-frame B-band curve, which we call the "composite curve." The same procedure is applied to 18 low-redshift Calán/Tololo SNe with z < 0.11; these nearly 300 B-band photometry points are found to lie on the composite curve equally well. The SCP search technique produces several measurements before maximum light for each supernova. We demonstrate that the linear stretch factor, s, which parameterizes the light-curve timescale, appears independent of z, and applies equally well to the declining and rising parts of the light curve. In fact, the B-band template that best fits this composite curve fits the individual supernova photometry data when stretched by a factor s with x2/dof ≈ 1 - thus, as well as any parameterization can, given the current data sets. The measurement of the date of explosion, however, is model dependent and not tightly constrained by the current data. We also demonstrate the 1 + z light-curve time-axis broadening expected from cosmological expansion. This argues strongly against alternative explanations, such as tired light, for the redshift of distant objects.

Review Of Silent Night: The Remarkable 1914 Christmas Truce, Michael F. Russo

Faculty Publications

No abstract provided.

Dirt Road Corrugations, Temple H. Fay, Keith A. Hardie, Stephan V. Joubert

Faculty Publications

WE CONSIDER FACTORS INFLUENCING the build-up of corrugations on dirt roads and the reactions of vehicles to them. We suggest that corrugations are (at least in part) a consequence of a natural tangential oscillation of the tread surface of the car lure that occurs when the vehicle is being driven or braked. Secondly, we suggest that the unpleasant vibration experienced by a vehicle passing over a corrugated road is the result of a beat produced by the difference of the frequency of oscillation of its own tyres and the frequency of the stimulation received by the vehicle due to passage …

Improving Cluster Utilization Through Set Based Allocation Policies, Quinn O. Snell, Julio C. Facelli, Brian D. Haymore, David B. Jackson

Faculty Publications

While clusters have already proven themselves in the world of high performance computing, some clusters are beginning to exhibit resource inefficiencies due to increasing hardware diversity. Much of the success of clusters lies in the use of commodity components built to meet various hardware standards. These standards have allowed a great level of hardware backwards compatibility that is now resulting in a condition referred to as hardware 'drift' or heterogeneity. The hardware heterogeneity introduces problems when diverse compute nodes are allocated to a parallel job, as most parallel jobs are not self-balancing. This paper presents a new method that allows …

Photon Decay At The Schwarzschild Horizon, Brett Altschul, R. Jackiw

Faculty Publications

A recent proposal that gravity theory is an emergent phenomenon also entails the possibility of photon decay near the Schwarzschild event horizon. We present a possible mechanism for such decay, which utilizes a dimensional reduction near the horizon. © 2001 Elsevier Science B.V.

Measurement Of The Cosmic-Ray Energy Spectrum And Composition From 1017 To 1018.3 Ev Using A Hybrid Technique, T. Abu-Zayyad, K. Belov, D. J. Bird, J. Boyer, Z. Cao, M. Catanese, G. F. Chen, R. W. Clay, C. E. Covault, H. Y. Dai, B. R. Dawson, J. W. Elbert, B. E. Fick, L. F. Fortson, J. W. Fowler, K. G. Gibbs, M. A.K. Glasmacher, K. D. Green, Y. Ho, A. Huang, C. C. Jui, M. J. Kidd, D. B. Kieda, B. C. Knapp, S. Ko, C. G. Larsen, W. Lee, E. C. Loh, E. J. Mannel, J. Matthews, J. N. Matthews, B. J. Newport, D. F. Nitz

Faculty Publications

We study the spectrum and average mass composition of cosmic rays with primary energies between 1017 and 1018 eV using a hybrid detector consisting of the High Resolution Fly's Eye (HiRes) prototype and the Michigan Muon Array (MIA). Measurements have been made of the change in the depth of shower maximum as a function of energy. A complete Monte Carlo simulation of the detector response and comparisons with shower simulations leads to the conclusion that the cosmic-ray intensity is changing from a heavier to a lighter composition in this energy range. The spectrum is consistent with earlier Fly's Eye measurements …

L-Cysteine-Mediated Destabilization Of Dinitrosyl Iron Complexes In Proteins, Paul A. Rogers, Huangen Ding

Faculty Publications

Nitric oxide is a signaling molecule in intercellular communication as well as a powerful weapon used by macrophages to kill tumor cells and pathogenic bacteria. Here, we show that when Escherichia coli cells are exposed to nitric oxide, its ferredoxin [2Fe-2S] cluster is nitrosylated, forming the dinitrosyl iron complex with a characteristic EPR signal at gav = 2.04. Such formed ferredoxin dinitrosyl iron complex is efficiently repaired in E. coli cells even in the absence of new protein synthesis. However, the repair activity is completely inactivated once E. coli cells are disrupted, indicating that repairing the ferredoxin dinitrosyl iron complex …

Crystal Growth, Structure Determination And Magnetism Of A New Hexagonal Rhodate: Ba9rh8o24, Katharine E. Stitzer, M. D. Smith, J. Darriet, Hans Conrad Zur Loye

Faculty Publications

Single crystals of Ba9Rh8O24, grown from a molten potassium carbonate flux, crystallize in the spacegroup R¯3c with lattice parameters of a = 10.0899(4) and c = 41.462(2) Å. Magnetic measurements on oriented single crystals reveal the existence of magnetic anisotropy

An Α-Helical Domain Within The Carboxyl Terminus Of Herpes Simplex Virus Type 1 (Hsv-1) Glycoprotein B (Gb) Is Associated With Cell Fusion And Resistance To Heparin Inhibition Of Cell Fusion, Timothy P. Foster, Jeff M. Melancon, Konstantin G. Kousoulas

Faculty Publications

Previous studies from our laboratory indicated that a 28-amino-acid carboxyl-terminal truncation of gB caused extensive virus-induced cell fusion (Baghian et al., 1993, J Virol 67, 2396-2401). We tested the ability of additional truncations and mutations within gB to cause cell fusion in the recently established virus-free cell fusion assay (Turner et al., 1998, J. Virol. 72, 873-875). Deletion of the carboxyl-terminal 28 amino acids of gB (gBΔ28), which removed part of the predicted α-helical structure H17b, caused extensive cell fusion. A gB truncation specified by gBΔ36, which removed the entire H17b domain, caused as much cell fusion as the gBΔ28 …

Two-Channel Kondo Lattice Model On A Ladder Studied By The Density-Matrix Renormalization-Group Method, Juana Moreno, Shaojin Qin, P. Coleman, Lu Yu

Faculty Publications

Using the density-matrix renormalization-group (DMRG) method we study a two-channel Kondo lattice model on a half-filled ladder. Our model involves an on-site s-wave and a nearest neighbor d-wave coupling between the local moments and the conduction electrons on the ladder. By changing the relative strength of the two Kondo interactions we examine the evolution of the system from a conventional Kondo insulator with a singlet at each site to a special kind of semimetallic state formed by overlapping of Zhang-Rice-like singlets. The DMRG is used to study how the spin and charge correlation functions evolve between these two regimes.

Commentary: Considerations For Use Of Racial/Ethnic Classification In Etiologic Research, Jay S. Kaufman, Richard S. Cooper

Faculty Publications

Numerous authors have critiqued the use of race as an etiologic quantity in medical research. Despite this criticism, the use of variables encoding racial/ethnic categorization has increased in epidemiology, and most researchers agree that important variation in disease risk is captured by this classification system. Previous discussions have generally neglected to articulate guidelines for appropriate use of racial/ethnic information in etiologic research. The authors summarize the logical, conceptual, and practical problems associated with the "ethnic paradigm" as currently applied in biomedical sciences and offer a set of methodological recommendations toward more valid use of racial/ethnic classification in etiologic studies. These …

Kaufman And Copper Respond To "Race,'Racism,And The Practice Of Epidemiology, Jay S. Kaufman, Richard S. Cooper

Faculty Publications

No abstract provided.

Measurement Of The Rate Of Ve + D → P + P + E− Interactions Produced By 8B Solar Neutrinos At The Sudbury Neutrino Observatory, Q. R. Ahmad, R. C. Allen, T. C. Andersen, J. D. Anglin, G. Bühler, J. C. Barton, E. W. Beier, M. Bercovitch, J. Bigu, S. Biller, R. A. Black, I. Blevis, R. J. Boardman, J. Boger, E. Bonvin, M. G. Boulay, M. G. Bowler, T. J. Bowles, S. J. Brice, M. C. Browne, T. V. Bullard, T. H. Burritt, K. Cameron, J. Cameron, Y. D. Chan, M. Chen, H. H. Chen, X. Chen

Faculty Publications

Solar neutrinos from 8B decay have been detected at the Sudbury Neutrino Observatory via the charged current (CC) reaction on deuterium and the elastic scattering (ES) of electrons. The flux of νe’s is measured by the CC reaction rate to be φCC(ve) = 1.75 ± 0.07(stat)+0.12−0.11(syst) ± 0.05(theor) × 106 cm−2s−1. Comparison of φCC(ve) to the Super-Kamiokande Collaboration’s precision value of the flux inferred from the ES reaction yields a 3.3σ difference, assuming the systematic uncertainties are normally distributed, providing evidence of an active non-ve component in the solar flux. The total flux of active 8B neutrinos is determined to …

Pulsed Atomic Layer Epitaxy Of Quaternary Alingan Layers, J. Zhang, E. Kuokstis, Q. Fareed, H. Wang, J. Yang, Grigory Simin, M. Asif Khan, R. Gaska, M. Shur

Faculty Publications

In this letter, we report on a material deposition scheme for quaternary Al_xIn_yGa_1−x–yN layers using a pulsed atomic layer epitaxy (PALE) technique. The PALE approach allows accurate control of the quaternary layer composition and thickness by simply changing the number of aluminum,indium, and gallium pulses in a unit cell and the number of unit cell repeats. Using PALE, AlInGaN layers with Al mole fractions in excess of 40% and strong room-temperature photoluminescence peaks at 280 nm can easily be grown even at temperatures lower than 800 °C.

Function Of Escherichia Coli Biotin Carboxylase Requires Catalytic Activity Of Both Subunits Of The Homodimer, Kamala Janiyani, Tee Bordelon, Grover L. Waldrop, John E. Cronan

Faculty Publications

Biotin carboxylase catalyzes the ATP-dependent carboxylation of biotin and is one component of the multienzyme complex acetyl-CoA carboxylase that catalyzes the first committed step in fatty acid synthesis. The Escherichia coli biotin carboxylase is readily isolated from the other components of the acetyl-CoA carboxylase complex such that enzymatic activity is retained. The three-dimensional structure of biotin carboxylase, determined by x-ray crystallography, demonstrated that the enzyme is a homodimer consisting of two active sites in which each subunit contains a complete active site. To understand how each subunit contributes to the overall function of biotin carboxylase, we made hybrid molecules in …

Statistics And Supermetallicity: The Metallicity Of Ngc 6791, B. J. Taylor

Faculty Publications

For the old galactic cluster NGC 6791, Peterson & Green (1998a) and Chaboyer et al. (1999) have found that [Fe/H] approximately + 0.4 dex. A second look at that conclusion is taken in this paper. Zero-point problems are reviewed for a high-dispersion analysis done by Peterson & Green, and it is found that accidental errors have not been determined rigorously for the results of that analysis. It is also noted that in a color-magnitude analysis performed by Chaboyer et al., the important metallicity range between 0.0 and + 0.3 dex is not explored and hence is not ruled out. Moreover, …

Evidence For Temperature Dependent Moments Ordering In Ferromagnetic Nimnsb(100), C. N. Borca, Takashi Komesu, Hae Kyung Jeong, P. A. Dowben, Delia Ristoiu, Ch Hordequin, J. P. Nozières, J. Pierre, Shane Stadler, Y. U. Idzerda

Faculty Publications

From magnetic circular dichroism measurements of the Heusler alloy NiMnSb, in combination with other techniques, we show that a dramatic increase in the Mn and Ni moments occurs below a "crossover" transition temperature of about 80-100 K. This phase transition is well below the Curie temperature of NiMnSb (∼730 K). While the spin polarization near the Fermi level, from spin-polarized inverse photoemission, remains very high for k=0, it is unlikely that NiMnSb is a half-metallic ferromagnet near room temperature.

Green Electrochemistry. Examples And Challenges, Michael A. Matthews

Faculty Publications

Electrochemical methods have been proposed for synthesis of organic compounds, including conversion of CO₂. Such methods may provide a basis for environmentally friendly and sustainable methods for chemical production. Nevertheless, electrochemical syntheses are not widely utilized. Several examples of ongoing research are presented that illustrate both the opportunities as well as the challenges associated with the utilization of electrochemistry for green chemical manufacturing.

Book Review: Changing History: Afro-Cuban Cabildos And The Societies Of Color In The Nineteenth Century, By Philip A. Howard, Matt D. Childs

Faculty Publications

No abstract provided.

Passivity-Based Control Of Saturated Induction Motors, Levent U. Gökdere, Marwan A. Simaan, Charles W. Brice

Faculty Publications

A passivity-based controller, which takes into account saturation of the magnetic material in the main flux path of the induction motor, is developed to provide close tracking of time-varying speed and flux trajectories in the high magnetic saturation regions. The proposed passivity based controller is experimentally verified. Also, a comparison between the controllers based on the saturated and nonsaturated magnetics is presented to demonstrate the benefit of the controller based on the saturated magnetics

The Effect Of Courtroom Technologies On And In Appellate Proceedings And Courtrooms, Fredric I. Lederer

Faculty Publications

No abstract provided.

The Decision To Breastfeed In The United States: Does Race Matter?, Renata Forste Phd, Jessica Weiss Bs, Emily Lippincott Bs

Faculty Publications

Objectives. To estimate the effects of maternal and birth characteristics on the decision to breastfeed and to relate breastfeeding practices to racial differences in infant mortality.

Methods. Using a sample of women with young children from the National Survey of Family Growth (NSFG), Cycle V, 1995, the likelihood of breastfeeding was modeled using logistic regression techniques. In addition, single, live births from the NSFG 1988 and 1995 surveys were analyzed to model the effects of race and breastfeeding on infant mortality using Cox regression methods.

Results. After controlling for socioeconomic background and birth characteristics, race remained a strong predictor of …

Livelock Avoidance For Meta-Schedulers, Mark J. Clement, John Jardine, Quinn O. Snell

Faculty Publications

Meta-scheduling, a process which allows a user to schedule a job across multiple sites, has a potential for livelock. Current systems avoid livelock by locking down resources at multiple sites and allowing a metascheduler to control the resources during the lock down period or by limiting job size to that which will fit on one site. The former approach leads to poor utilization; the later poses limitations on job size. This research uses BYU's Meta-scheduler (YMS) which allows jobs to be scheduled across multiple sites without the need for locking down the nodes. YMS avoids livelock through exponential back-off This …

Spline Based Path Planning For Unmanned Air Vehicles, Kevin B. Judd, Timothy W. Mclain

Faculty Publications

A trajectory planning scheme that generates feasible flight routes for an unmanned air vehicle (UAV) is developed. A preliminary path is generated from a Voronoi diagram based on threat locations. This path consists of a series of straight-line segments that cannot be followed exactly by the UAV. Using a series of cubic splines to connect these straight-line segments, this path is refined into an optimum path that is flyable by the UAV. Utilizing a decomposition strategy, both the full path (coarse detail) to the target and the proximate optimum path (fine detail) near the UAV can be quickly computed. The …

The Scientific Foundations Of Habitat Conservation Plans: A Quantitative Assessment, Elaine K. Harding, Elizabeth E. Crone, Bret D. Elderd, Jonathan M. Hoekstra, Alexa J. Mckerrow, John D. Perrine, Jim Regetz, Leslie J. Rissler, Amanda G. Stanley, Eric L. Walters

Faculty Publications

The number of habitat conservation plans (HCP) has risen dramatically since the first plan was written over 18 years ago. Until recently, no studies have quantitatively investigated the scientific foundations underlying these documents. As part of a larger study of HCPs, we examined 43 plans primarily to assess the availability and use of scientific data and secondarily to determine the extent of involvement by, and influence of independent scientists within the process. Specifically, our analysis focused on five key steps taken when an HCP is developed: assessing status of a species, determining take, predicting the project effects, mitigating for those …

Quasi-Su(3) Truncation Scheme For Even-Even Sd-Shell Nuclei, C. E. Vargas, J. G. Hirsch, J. P. Draayer

Faculty Publications

The quasi-SU(3) symmetry was uncovered in full pf and sdg shell-model calculations for both even-even and odd-even nuclei. It manifests itself through a dominance of single-particle and quadrupole-quadrupole terms in a Hamiltonian used to describe well-deformed nuclei. A practical consequence of the quasi-SU(3) symmetry is an efficient basis truncation scheme. In [C.E. Vargas et al., Phys. Rev. C 58 (1998) 1488] it is shown that when this type of Hamiltonian is diagonalized in an SU(3) basis, only a few irreducible representations (irreps) of SU(3) are needed to describe the yrast band, the leading S=0 irrep augmented with the leading S=1 …

Comment On "Observation Of Superluminal Behaviors In Wave Propagation", Harry Ringermacher, Lawrence R. Mead

Faculty Publications

No abstract provided.

Electromagnetics, David V. Arnold, Richard H. Selfridge, Karl F. Warnick

Faculty Publications

Many applications of electrical engineering require a knowledge of the behavior of voltages and currents in electronic devices and within conductors. In many other situations it is not enough to understand the behavior the voltages and currents in just the conductors and other components, but also the influence of the voltage and current on surrounding materials.

Observation Of An Anomalous Number Of Dimuon Events In A High Energy Neutrino Beam, T. Adams, A. Alton, S. Avvakumov, L. De Barbaro, P. De Barbaro, R. H. Bernstein, A. Bodek, T. Bolton, J. Brau, D. Buchholz, H. Budd, L. Bugel, J. Conrad, R. B. Drucker, B. T. Fleming, R. Frey, J. A. Formaggio, J. Goldman, M. Goncharov, D. A. Harris, R. A. Johnson, J. H. Kim, S. Koutsoliotas, M. J. Lamm, W. Marsh, D. Mason, J. Mcdonald, C. Mcnulty, K. S. Mcfarland, D. Naples, P. Nienaber, A. Romosan, W. K. Sakumoto

Faculty Publications

A search for long-lived neutral particles (N0’s) with masses above 2.2GeV/c2 that decay into at least one muon has been performed using an instrumented decay channel at the NuTeV experiment at Fermilab. Data were examined for particles decaying into the final states μμ, μe, and μ π . Three μ μ events were observed over an expected standard model background of 0.069 ± 0.010 events; no events were observed in the other modes. © 2001 American Physical Society.