Digital Commons Network^™

New Techniques To Determine Ages Of Open Clusters Using White Dwarfs, E. J. Jeffery, Ted Von Hippel, Et Al.

Publications

Currently there are two main techniques for independently determining the ages of stellar populations: main-sequence evolution theory (via cluster isochrones) and white dwarf cooling theory. Open clusters provide the ideal environment for the calibration of these two clocks. Because current techniques to derive cluster ages from white dwarfs are observationally challenging, we discuss the feasibility of determining white dwarf ages from the brighter white dwarfs alone. This would eliminate the requirement of observing the coolest (i.e., faintest) white dwarfs. We discuss our method for testing this new idea, as well as the required photometric precision and prior constraints on metallicity, …

Poisson-Boltzmann Calculations Of Nonspecific Salt Effects On Protein-Protein Binding Free Energies, Claudia Bertonati, Barry Honig, Emil Alexov

Publications

The salt dependence of the binding free energy of five protein-protein hetero-dimers and two homo-dimers/tetramers was calculated from numerical solutions to the Poisson-Boltzmann equation. Overall, the agreement with experimental values is very good. In all cases except one involving the highly charged lactoglobulin homo-dimer, increasing the salt concentration is found both experimentally and theoretically to decrease the binding affinity. To clarify the source of salt effects, the salt-dependent free energy of binding is partitioned into screening terms and to self-energy terms that involve the interaction of the charge distribution of a monomer with its own ion atmosphere. In six of …

Bifurcations Of Plane Wave (Cw) Solutions In The Complex Cubic-Quintic Ginzburg-Landau Equation, S.C. Mancas, S. Roy Choudhury

Publications

Singularity Theory is used to comprehensively investigate the bifurcations of the steady-states of the traveling wave ODEs of the cubic-quintic Ginzburg-Landau equa- tion (CGLE). These correspond to plane waves of the PDE. In addition to the most general situation, we also derive the degeneracy conditions on the eight coefficients of the CGLE under which the equation for the steady states assumes each of the possible quartic (the quartic fold and an unnamed form), cubic (the pitchfork and the winged cusp), and quadratic (four possible cases) normal forms for singularities of codimension up to three. Since the actual governing equations are …

The Complex Cubi-Quintic Ginzburg-Landau Equation: Hopf Bifurcations Yielding Traveling Waves, S.C. Mancas, S. Roy Choudhury

Publications

In this paper we use a traveling wave reduction or a so{called spatial approxima- tion to comprehensively investigate the periodic solutions of the complex cubic{quintic Ginzburg{Landau equation. The primary tools used here are Hopf bifurcation theory and perturbation theory. Explicit results are obtained for the post{bifurcation periodic orbits and their stability. Generalized and degenerate Hopf bifurcations are also brie y considered to track the emergence of global structure such as homoclinic orbits.

The Metallicity Distribution Of Intracluster Stars In Virgo, Benjamin F. Willaims, Ted Von Hippel, Et Al.

Publications

We have used the Hubble Space Telescope's Advanced Camera for Surveys (ACS) to detect and measure ~5300 stars in a single intracluster field in the Virgo Cluster. By performing F606W and F814W photometry on these stars, we have determined their metallicity distribution function and constrained the types of stars present in this portion of Virgo's intracluster space. Based on the small number of stars detected that were brighter than the red giant branch (RGB) tip, we suggest that in this region, Virgo's intracluster stars are mostly old (10 Gyr). Through analysis of the RGB stars themselves, we determine that …

The Resolved Stellar Populations Of A Dwarf Spheroidal Galaxy In The Virgo Cluster, Patrick R. Durell, Ted Von Hippel, Et Al.

Publications

We report on the discovery of a faint (MV ~ -10.6 ± 0.2) dwarf spheroidal galaxy on deep F606W and F814W Hubble Space Telescope images of a Virgo intracluster field. The galaxy is easily resolved in our images, as our color magnitude diagram (CMD) extends 1 magnitude beyond the tip of the red giant branch (RGB). Thus, it is the deepest CMD for a small dwarf galaxy inside a cluster environment. Using the colors of the RGB stars, we derive a metal abundance for the dwarf of [M/H] = -2.3 ± 0.3 and show that the metallicity dispersion …

Time-Resolved Ducting Of Atmospheric Acoustic-Gravity Waves By Analysis Of The Vertical Energy Flux, Yonghui Yu, Michael P. Hickey Ph.D.

Publications

A new 2-D time-dependent model is used to simulate the propagation of an acoustic-gravity wave packet in the atmosphere. A Gaussian tropospheric heat source is assumed with a forcing period of 6.276 minutes. The atmospheric thermal structure creates three discrete wave ducts in the stratosphere, mesosphere, and lower thermosphere, respectively. The horizontally averaged vertical energy flux is derived over altitude and time in order to examine the time-resolved ducting. This ducting is characterized by alternating upward and downward energy fluxes within a particular duct, which clearly show the reflections occurring from the duct boundaries. These ducting simulations are the first …

Soldier/Hardware-In-The-Loop Simulation-Based Combat Vehicle Duty Cycle Measurement: Duty Cycle Experiment 2, Mark Brudnak, Mike Pozolo, Victor Paul, Syed Mohammad, Marc Compere, Et Al.

Publications

This paper describes a human-in-the-loop motion-based simulator interfaced to hybrid-electric power system hardware both of which were used to measure the duty cycle of a combat vehicle in a virtual simulation environment. The project discussed is a greatly expanded follow-on to the experiment published in [1]. This paper is written in the context of [1] and therefore highlights the enhancements. The most prominent of these enhancements is the integration (in real-time) of the Power & Electric System Integration Lab (P&E SIL) with a motion base simulator by means of a “long haul” connection over the Internet (a geographical distance of …

A Dyad Theory Of Hydrodynamics And Electrodynamics, Preston Jones

Publications

The dyadic calculus is developed in a form suitable for the description of physical relations in curved space. The 4-space equations of hydrodynamics and electrodynamics are constructed using this dyadic calculus. As a demonstration of the relationship between gravity and electrodynamics a time varying metric is shown to generate electromagnetic radiation.

Chemical And Dynamical Processes In The Mesospheric Emissive Layer. First Results Of Stereoscopic Observations, M. Faivre, G. Moreels, Pierre-Dominique Pautet, J. Clairemidi, F. Dumont, O. Lorin, F. Colas

Publications

[1] The mesospheric emissive layer is an efficient tracer of the dynamical processes propagating in the atmosphere at that level. CCD images in the near infrared taken from the ground at slant angles often reveal the existence of wavy fields. A series of such images has been transformed, using matrix operations, producing a downward satellite-type view that covers a circular area of radius ∼1000 km at the altitude of the layer. The Fourier characteristics of the wave system are measured using a Morlet-type wavelet generator function with horizontal wavelengths of mostly ∼20–40 km and 100–150 km and temporal periods of …

Virgo’S Intracluster Globular Clusters As Seen By The Advanced Camera For Surveys, Benjamin F. Williams, Robin Ciardullo, Ted Von Hippel, Et Al.

Publications

We report the discovery of four candidate intracluster globular clusters (IGCs) in a single deepHST ACS field of the Virgo Cluster. We show that each cluster is roughly spherical, has a magnitude near the peak of the Virgo globular cluster luminosity function, has a radial profile that is best fitted by a King model, and is surrounded by an excess of point sources that have the colors and magnitudes of cluster red giant stars. Despite the fact that two of our IGC candidates have integrated colors redder than the mean of the M87 globular cluster system, we propose that …

Should There Be A National Curriculum For Technological Literacy?, Laura J. Hummell, Ethan B. Lipton, Melissa Morrow, Jerry Streichler, Karen Zuga

Publications

The author discusses her belief that the United States should have a national curriculum for technological literacy. The author asserts that there are huge discrepancies and deficiencies existing in technology-based curricula, and as a result students in the United States are being ill-prepared for living and working in a globally based economy and society. The author believes that if a national curriculum for technological literacy is developed it should resemble the Standards for Technological Literacy (2000/2002), which was created by the International Technology Education Association. The author points out that in order for such a curriculum to be successful it …

Curricular Value And Instructional Needs For Infusing Engineering Design Into K-12 Technology Education, David K. Gattie, Robert C. Wicklein

Publications

An overarching objective of Technology Education in the U.S. is to improve technological literacy among K-12 students (DeVore, 1964; Savage and Sterry, 1990; International Technology Education Association, 1996, 2000, 2003). This is addressed in part through a focus on end-product technology and the use and importance of various technologies in society (Savage and Sterry, 1990). While such a focus is certainly necessary, it may not be sufficient if the objective is to infuse engineering into the technology education field. Current efforts at the University of Georgia propose adjusting the focus of Technology Education to a defined emphasis on engineering design …

Critical Features Of Engineering Design In Technology Education, Paul A. Asunda, Roger Hill

Publications

The purpose of this study was to find critical features of engineering design that can be incorporated within technology education learning activities, and develop a rubric for assessing these features. Data were collected through semi-structured interviews with three professors actively involved in engineering education. Supporting documents such as engineering design course outlines and rubrics were also examined. Using a phenomenological approach, this study identified the concept of engineering design, key features of the engineering design process, and critical elements that should be assessed in an engineering design activity in the context of technology education. A key product of the study …

Wind Damage And Salinity Effects Of Hurricanes Katrina And Rita On Coastal Baldcypress Forests Of Louisiana, William Conner, Thomas W. Doyle, Richard H. Day, Ken W. Krauss, Christopher M. Swarzenski

Publications

The frequency of hurricane landfall in a given coastal stretch may play a more important role in the ecology of coastal forests than previously thought because of direct and indirect impacts of fallen trees and the introduction of salt water that lingers long after the storm passes. Findings show that surge events can inundate interior freshwater forests many miles from the coast and elevate soil salinities twofold to threefold. These elevated salinities may contribute to delayed mortality of certain tree species and set the stage for eventual forest decline and dieback.

Science And The Storms: The Usgs Response To The Hurricanes Of 2005 - Chapter Six: Ecological Impacts, William Conner, Stephen Faulkner, Wylie Barrow, Brady Couvillion, Lori Randall, Michael Baldwin

Publications

Ecological impacts from the hurricanes of 2005 affected both vegetation and the animals that depend on coastal habits on land and in water. Discussed in this section are migratory birds, coastal marsh vegetation, chenier forests, coastal floodplain forests, mangrove forests, estuaries, and the endangered manatee.

Economic Impact Of Ubiquitous Wireless Internet In South Carolina, 2007 January, Robert T. Carey, Camilla Hertwig

Publications

No abstract provided.

Downscaling Daily Maximum And Minimum Air Temperature In The Midwestern Usa: A Hybrid Empirical Approach, Justin T. Schoof, S C. Pryor, S M. Robeson

Publications

A new hybrid empirical downscaling technique is presented and applied to assess 21st century projections of maximum and minimum daily surface air temperatures (Tmax, Tmin) over the Midwestern USA. Our approach uses multiple linear regression to downscale the seasonal variations of the mean and standard deviation of daily Tmax and Tmin and the lag-0 and lag-1 correlations between daily Tmax and Tmin based on GCM simulation of the large-scale climate. These downscaled parameters are then used as inputs to a stochastic weather generator to produce time series of the daily Tmax and Tmin at 26 surface stations, in three time …

Phylogenetic Relationships And Ecological Speciation In The Mistletoe Tristerix (Loranthaceae): The Influence Of Pollinators, Dispersers, And Hosts, Amico C. Guillermo, Romina Vidal-Russel, Daniel L. Nickrent

Publications

Phylogenies can provide valuable information on biotic and abiotic factors associated with speciation. We examined species relationships in Tristerix (Loranthaceae), a genus of 11 species with an Andean distribution from Colombia to Chile. A previous classification divided Tristerix into subgenera Tristerix (two species) and Metastachys (nine species). We tested this classification by generating a molecular phylogeny of the genus using nuclear ribosomal DNA ITS and chloroplast atpB-rbcL intergenic spacer and trnL-F regions. All partitions generally gave congruent trees, thus a combined analysis was conducted. Tristerix was composed of a northern clade (six species) and a southern clade (four species). Tristerix …

Heating Methods And Detection Limits For Infrared Thermography Inspection Of Fiber-Reinforced Polymer Composites, Jeff R. Brown, H. R. Hamilton

Publications

The use of fiber-reinforced polymer (FRP) composites to strengthen existing civil infrastructure is expanding rapidly. Many FRP systems used to strengthen reinforced concrete are applied using a wet lay-up method in which dry fibers are saturated on site and then applied to the surface. This research investigated using infrared thermography (IRT) as a nondestructive evaluation (NDE) tool for detecting air voids and epoxy-filled holes in FRP systems bonded to a concrete substrate. Four small-scale specimens with FRP thicknesses ranging from 1 to 4 mm (0.04 to 0.16 in.) containing fabricated defects were constructed and inspected in a laboratory setting. Three …

Laws Against Bubbles: An Experimental-Asset-Market Approach To Analyzing Financial Regulation, Erik F. Gerding

Publications

This article analyzes the effectiveness of proposed and actual securities, financial, and tax laws designed to prevent, or dampen the severity of asset price bubbles, including laws designed to mitigate excessive speculation. The article employs experimental asset market research to measure the effectiveness of these anti-bubble laws in correcting mispricings. Experimental asset markets represent complex simulations of stock markets in which subjects trade securities over a computer network. These markets allow scholars to test causal links between legal policies and market effects in ways that empirical research alone cannot. With these virtual markets, researchers can identify asset price bubbles - …

An External Perspective On The Nature Of Noneconomic Compensatory Damages And Their Regulation, Ronald J. Allen, Alexia Brunet, Susan Spies Roth

Publications

No abstract provided.

Illuminating Secrecy: A New Economic Analysis Of Confidential Settlements, Scott A. Moss

Publications

Even the most hotly contested lawsuits typically end in a confidential settlement forbidding the parties from disclosing their allegations, evidence, or settlement amount. Confidentiality draws fierce criticism for harming third parties by concealing serious misdeeds like discrimination, pollution, defective manufacturing, and sexual abuse. Others defend confidentiality as a mutually beneficial pay-for-silence bargain that facilitates settlement, serves judicial economy, and prevents frivolous copycat lawsuits. This debate is based in economic logic, yet most analyses have been surprisingly shallow as to how confidentiality affects incentives to settle. Depicting a more nuanced, complex reality of litigation and settlement, this Article reaches several conclusions …

The Patent Office Meets The Poison Pill: Why Legal Methods Cannot Be Patented, Andrew A. Schwartz

Publications

In 2003, for the first time in its 170-year history, the United States Patent Office began awarding patents for novel legal innovations, in addition to traditional inventions such as the telephone or airplane. Commentators have accepted the Patent Office's power to grant legal method patents, but at the same time have criticized this new type of patent on policy grounds. But no one has suggested that the Patent Office exceeded its authority by awarding patents for legal methods, until now.

In the Patent Act of 1952, which is still in effect today, Congress established certain requirements for patentability, including a …

Data Mining Methods Applied To Flight Operations Quality Assurance Data: A Comparison To Standard Statistical Methods, Alan J. Stolzer, Carl Halford

Publications

"In a previous study, multiple regression techniques were applied to Flight Operations Quality Assurance-derived data to develop parsimonious model(s) for fuel consumption on the Boeing 757 airplane. The present study examined several data mining algorithms, including neural networks, on the fuel consumption problem and compared them to the multiple regression results obtained earlier. Using regression methods, parsimonious models were obtained that explained approximately 85% of the variation in fuel flow. In general data mining methods were more effective in predicting fuel consumption. Classification and Regression Tree methods reported correlation coefficients of .91 to .92, and General Linear Models and Multilayer …

Book Review: No Place To Hide, Gary C. Kessler

Publications

This document is Dr. Kessler's review of No Place to Hide, by Robert O'Harrow, Jr. Free Press, 2006. ISBN 0-7432-8705-3.

Multiphoton Response Of Retinal Rod Photoreceptors, Vasilios Alexiades, Harihar Khanal

Publications

Phototransduction is the process by which light is converted into an electrical response in retinal photoreceptors. Rod photoreceptors contain a stack of (about 1000) disc membranes packed with photopigment rhodopsin molecules, which absorb the photons. We present computational experiments which show the profound effect on the response of the distances (how many discs apart) photons happen to be absorbed at. This photon-distribution effect alone can account for much of the observed variability in response.

Book Review: Conquest In Cyberspace: National Security And Information Warfare, Gary C. Kessler

Publications

This document is Dr. Kessler's review of Conquest in Cyberspace: National Security and Information Warfare, by Martin C. Libicki. Cambridge University Press, 2007. ISBN 978-0-521-69214-4

Oscillation Criteria For First-Order Forced Nonlinear Difference Equations, Ravi P. Agarwal, Said R. Grace, Tim Smith

Publications

Some new criteria for the oscillation of first-order forced nonlinear difference equations are established.

Early-Time Chromatic Variations In The Wind-Swept Medium Of Grb 021211 And The Faintness Of Its Afterglow, M. C. Nysewander, D. E. Reichart, H.-S. Park, G. G. Williams, K. Kinugasa, D. Q. Lamb, A. A. Henden, S. Klose, T. Kato, A Harper, H Yamaoka, C Laws, K Torii, D G. York, J C. Barentine, J Dembicky, R J. Mcmillan, J A. Moran, Dieter H. Hartmann, B Ketzeback, M B. Bayliss, J A. Crain, A C. Foster, M Schwartz, P Holvorcem, P A. Price, R Canterna, G B. Crew, G R. Ricker, S D. Barthelmy

Publications

We present Follow-Up Network for Gamma-Ray Bursts (FUN GRB) Collaboration observations of the optical afterglow of GRB 021211 made between 143 s and 102 days after the burst. Our unique data set includes the earliest filtered detections and color information for an afterglow in the pre-Swift era. We find that the afterglow is best described by (1) a propagation through a wind-swept medium, (2) a cooling break that is blueward of the observed optical frequencies, and (3) a hard electron energy distribution. However, superimposed on this ‘‘standard model’’ behavior we find, one and possibly two, significant chromatic variations during the …