Physical Sciences and Mathematics Commons^™

“Every Breath You Take... ”: The Demographics Of Toxic Air Releases In Southern California, James Sadd, Manuel Pastor, J. Boer, Lori Snyder

James Sadd

In this article, the authors investigate the relationship between ethnicity and potential environmental hazards in the metropolitan Los Angeles area. Using a variety of techniques, including geographic information systems (GIS) mapping, univariate comparisons, and logit, ordered logit, and tobit regression analysis, the authors find that, even controlling for other factors such as income and the extent of manufacturing employment and land use, minority residents tend to be disproportionately located in neighborhoods surrounding toxic air emissions. The results generally support the propositions of the proponents of “environmental justice”; in the conclusion, they consider what this might mean for urban land use …

The Correlation Of Physical Properties Of Organic Molecules With Computed Molecular Surface Areas., Robert Mebane, Shannon Schanley, Thomas Rybolt, Chrystal Bruce

Chrystal D. Bruce

The objective of this paper is to show that a student's understanding of molecular properties can be enhanced with the study of molecular surface areas obtained from readily available molecular modeling software.

Radiocarbon Chronology And Δ13c Analysis Of Mid-To Late-Holocene Aeolian Environments, Guadalupe Mountains National Park, Texas, Usa, David Wilkins, Donald Currey

David E. Wilkins

The Red Dunes of Guadalupe Mountains National Park are quartzose sand sheets and dunes stabilized by sparse plant cover. Stratigraphy, radiocarbon dating, and δ13C analysis were examined in two of the larger arroyos for correlating evidence of aeolian deposition, which in this basin is taken as an indication of arid conditions. Four quartz-sand lithostratigraphic units, representing intervals of aeolian activity, are identified. Radiocarbon dates provide constraint on the timing of the three youngest quartz-sand units. A mid-Holocene aeolian interval, represented by a single radiocarbon date of 6350± 70 BP, is interpreted as transitional to an altithermal regime. A neopluvial period, …

The Spectral Function Of Composites: The Inverse Problem, Anthony Day, M. Thorpe

Anthony Roy Day

No abstract provided.

Elastic And Shear Moduli Of Single-Walled Carbon Nanotube Ropes, Nancy Burnham, Jean-Paul Salvetat, G Andrew D Briggs, Jean-Marc Bonard, Revathi Bacsa, Andrzej Kulik, Thomas Stöckli, László Forró

Nancy A. Burnham

Carbon nanotubes are believed to be the ultimate low-density high-modulus fibers, which makes their characterization at nanometer scale vital for applications. By using an atomic force microscope and a special substrate, the elastic and shear moduli of individual single-walled nanotube (SWNT) ropes were measured to be of the order of 1 TPa and 1 GPa, respectively. In contrast to multiwalled nanotubes, an unexpectedly low intertube shear stiffness dominated the flexural behavior of the SWNT ropes. This suggests that intertube cohesion should be improved for applications of SWNT ropes in high-performance composite materials.

Synthesis Of Bulk Polycrystalline Indium Nitride At Subatmospheric Pressures., Jeffrey Dyck, K. Kash, C. Hayman, A. Argoitia, M. Grossner, J. Angus, W.-L. Zhou

Jeffrey Dyck

Polycrystalline, wurtzitic indium nitride was synthesized by saturating indium with nitrogen from microwave plasma sources. The structure was confirmed by x-ray diffraction, electron diffraction, and elemental analysis. Two types of growth were observed: (i) dendritic crystals on the original melt surface, and (ii) hexagonal platelets adjacent to the In metal source on the upper edge of the crucible. The method does not involve a foreign substrate to initiate growth and is a potential alternative to the high-pressure techniques normally associated with bulk growth of indium nitride. The lattice parameters were a = 3.5366 ± 0.0005 angstrom and c = 5.7009 …

Mathematica In Action, Stan Wagon

Stan Wagon, Retired

No abstract provided.

Optimization Methods For Logical Inference, Vijay Chandru, John Hooker

John Hooker

No abstract provided.

Invertibly Convergent Infinite Products Of Matrices, William F. Trench

William F. Trench

No abstract provided.

Projections Of Alzheimer's Disease In The United States And The Public Health Impact Of Delaying Disease Onset., Ron Brookmeyer, Sarah Gray, Claudia Kawas

Ron Brookmeyer

OBJECTIVES: The goal of this study was to project the future prevalence and incidence of Alzheimer's disease in the United States and the potential impact of interventions to delay disease onset.

METHODS: The numbers of individuals in the United States with Alzheimer's disease and the numbers of newly diagnosed cases that can be expected over the next 50 years were estimated from a model that used age-specific incidence rates summarized from several epidemiological studies, US mortality rates, and US Bureau of the Census projections.

RESULTS: in 1997, the prevalence of Alzheimer's disease in the United States was 2.32 million (range: …

Analytical Mechanics, Janet Scheel, Louis Hand

Janet D. Scheel

No abstract provided.

Charge Density Wave Caused By Reducing Thse3 By One Electron. Superstructure And Short-Range Order In Ath2se6 (A = K, Rb) Studied By X-Ray Diffraction, Electron Diffraction, And Diffuse Scattering, Kyoung-Shin Choi, Rhonda Patschke, Simon Billinge, Mark Waner, Marcos Dantus, Mercouri Kanatzidis

Mark J. Waner

Charge Density Wave Caused by Reducing ThSe3 by One Electron. Superstructure and Short-Range Order in ATh2Se6 (A = K, Rb) Studied by X-ray Diffraction, Electron Diffraction, and Diffuse Scattering

Two-Surface Virial Analysis Of Alkane Adsorption On Carbopack C With And Without Hydrogen Treatment., Chrystal Bruce, Thomas Rybolt, Howard Thomas, Tara Agnew, Brandon Davis

Chrystal D. Bruce

Second gas–solid virial coefficients for propane, butane, pentane, and hexane were found for Carbopack C and Carbopack C-HT (Supelco Inc.) within the temperature range of 323 to 471 K using gas–solid chromatography in the Henry's law region of adsorption. Carbopack C and Carbopack C-HT are both graphitized carbon black powders. Treatment of Carbopack C with hydrogen at 1273 K converts it to Carbopack C-HT and is believed to remove certain high energy sites or “hot spots” from the carbon surface. These two surfaces provide appropriate model systems to test a two-surface virial analysis. Surface areas for both powders were calculated …

The Penrose Dodecahedron Revisited, Padmanabhan Aravind, Jordan Massad

Padmanabhan K. Aravind

This paper gives an elementary account of the ‘‘Penrose dodecahedron,’’ a set of 40 states of a spin- 3 2 particle used by Zimba and Penrose @Stud. Hist. Phil. Sci. 24, 697–720 ~1993!# to give a proof of Bell’s nonlocality theorem. The Penrose rays are constructed here from the rotation operator of a spin- 3 2 particle and the geometry of a dodecahedron, and their orthogonality properties are derived and illustrated from a couple of different viewpoints. After recalling how the proof of Bell’s theorem can be reduced to a coloring problem on the Penrose rays, a ‘‘proof-tree’’ argument is …

Experimental Studies Of Fe-Mg Carbonates And Their Role In Petrogenesis

Andrea M. Koziol

A Heavy Top Quark From Flavor-Universal Colorons, Marko Popovic, Elizabeth Simmons

Marko B. Popovic

Ordinary technicolor and extended technicolor cannot produce the heavy top quark unaided. We demonstrate that a flavor-universal extension of the color interactions combined with an extended hypercharge sector that singles out the third generation can provide the necessary assistance. We discuss current experimental constraints and suggest how collider experiments can search for the predicted new heavy gauge bosons.

‘Race, Gender And Justice’: New Technologies And Student Empowerment, Ron Buckmire, Donna Maeda, Gabrielle Foreman

Ron Buckmire

No abstract provided.

Improving Performance By Branch Reordering, Minghui Yang, Gang-Ryung Uh, David B. Whalley

Gang-Ryung Uh

Friction Anisotropy And Asymmetry Of A Compliant Monolayer Induced By A Small Molecular Tilt, Nancy Burnham, M Liley, D. Gourdon, Dimitrios Stamou, U Meseth, T Fischer, C Lautz, H Stahlberg, H Vogel, C Duschl

Nancy A. Burnham

Lateral force microscopy in the wearless regime was used to study the friction behavior of a lipid monolayer on mica. In the monolayer, condensed domains with long-range orientational order of the lipid molecules were present. The domains revealed unexpectedly strong friction anisotropies and non-negligible friction asymmetries. The angular dependency of these effects correlated well with the tilt direction of the alkyl chains of the monolayer, as determined by electron diffraction and Brewster angle microscopy. The molecular tilt causing these frictional effects was less than 15 degrees, demonstrating that even small molecular tilts can make a major contribution to friction.

Synthesis Of Licoo2 Powders For Lithium-Ion Batteries From Precursors Derived By Rotary Evaporation., P. Kumpta, D. Gallet, A. Waghray, G. Blomgren, Michael Setter

Michael P. Setter

Lithium cobalt oxide (LiCoO2) has received considerable attention in the last few years and is a well-known cathode material for high voltage (4 V) rechargeable Li-ion batteries. A simple chemical approach based on aqueous solution chemistry has been developed to synthesize molecularly mixed amorphous precursors. The precursors begin to transform to form LiCoO2 upon heat treatment at temperatures as low as 400°C. Strong peaks characteristic of the desired high temperature (HT) phase of LiCoO2 evolve when the precursors are heat treated to 800°C for 2 h. The morphology and particle size of the powders have been examined using scanning electron …

The Voltammetry Of C84 Isomers, Mark Anderson, Harry Dorn, Steven Stevenson, Susanne Dana

Mark R. Anderson

The square-wave voltammetry of isolated isomers of C84 is reported. Based on their relative abundance, the isomers are assumed to have D2 and D2d symmetry. The D2 isomer has four reversible reductions at −0.65, −0.98, −1.34, and −1.75 V versus Fc/Fc+ prior to electrolyte decomposition. This behavior is consistent with previous reports, and is similar to the voltammetry of C60 and C70 (e.g. sequential reductions spaced at slightly increasing intervals). The D2d isomer has five reversible reductions at −0.46, −0.77, −1.58, −1.98, and −2.27 V versus Fc/Fc+ prior to the onset of electrolyte decomposition. The large potential difference separating the …

Imaging The Molecular Dimensions And Oligomerization Of Proteins At Liquid/Solid Interfaces, Mark Waner, Martha Gilchrist, Melvin Schindler, Marcos Dantus

Mark J. Waner

Individual Concanavalin A (ConA) molecules have been imaged at the liquid/solid interface with an atomic force microscope (AFM). Three-dimensional sizing with very high resolution (<5 Å) has been obtained by a novel approach based on height distributions, which avoids the tip convolution effects which normally affect scanning probe microscopy techniques. Each height measurement correlates to a particular molecular orientation on the surface. A large number of such measurements provide a statistical ensemble of orientations. The complete height distribution reflects the three-dimensional size of the protein sample and hence its tertiary and quaternary structure. A surface adsorption and orientation model, based on a minimization of surface adsorption energy, is proposed. This model is in good agreement with the observed height distribution of Con A molecules at the liquid/solid interface. Analysis of Con A and succinylated Con A molecules on mica demonstrates that Con A dimers are the prevalent species at the liquid/solid interface. This is in contrast to the tetrameric organization of Con A normally observed in solution. The new possibilities opened by height distribution analysis on the physical characterization of biomolecules at interfaces are also discussed.

Active Tectonics And Ultrahigh-Pressure Rocks, Ann Blythe

Ann Blythe

This chapter compares modern exhumation and surface uplift rates with the rates needed for the preservation of ultrahigh pressure (UHP) metamorphic rocks. The highest recorded exhumation rates of ~ 5–10 mm/a are inferred from isotopic and fission-track analyses in the Himalaya, Southern Alps of New Zealand, and D’Entrecasteaux Islands. Similar rates (~7 mm/a) of surface uplift are measured from leveling surveys in Nepal and correlations of marine terraces in the Southern Alps. In Nepal, however, this surface uplift rate is occurring despite erosion, and the true rate of surface uplift is probably considerably higher. In restraining bends along the San …

Using An E-Mail Tutorial And Student Seminars To Improve An Intermediate-Level Undergraduate Physics Course, Janet Scheel

Janet D. Scheel

The authors revised the junior-level classical mechanics course at Cornell University to incorporate asynchronous, autonomous, and group learning. We created an E-mail tutorial and a student seminar. We will first discuss the theoretical background for these changes and then describe the results of their implementation over a period of three years.

Longitudinal Study Of Dental Development In Chimpanzees Of Known Chronological Age: Implications For Understanding The Age At Death Of Plio-Pleistocene Hominids, Robert Anemone, Mark Mooney

Robert L. Anemone

Reconstruction of life history variables of fossil hominids on the basis of dental development requires understanding of and comparison with the pattern and timing of dental development among both living humans and pongids. Whether dental development among living apes or humans provides a better model for comparison with that of Plio-Pleistocene hominids of the genus Australopithecus remains a contentious point. This paper presents new data on chimpanzees documenting developmental differences in the dentitions of modern humans and apes and discusses their significance in light of recent controversies over the human or pongid nature of australopithecine dental development. Longitudinal analysis of …

Cloning And Conservation Of Biological Diversity: Paradox, Panacea, Or Pandora's Box?, Shaily Menon, Kamaljit Bawa, Leah Gorman

Shaily Menon

The success of a Scottish team in cloning a mammal from an adult tissue cell has generated considerable speculation in the popular press about potential applications to conservation biology. Possibilities that have been mentioned include cloning endangered species and creating gene banks for the germplasm of rare species. Sensational or inaccurate reports might encourage the mistaken notion that cloning technology is more advanced or reliable than it actually is. More important, such reports might foster the myth that there is no longer an urgency to conserve endangered species or their habitats as long as we have frozen germplasm and cloning …

Synthesis Of [15n,15n‘]-N,N,N‘,N‘-Tetramethyl- Ethylenediamine And Its Use In Solvation Studies Of [6li]-N-Butyllithium., Delia Waldmüller, Barbara Kotsatos, Michael Nichols, Paul Williard

Michael A Nichols

No abstract provided.

Timing And Extent Of Late Quaternary Paleolakes In The Trans-Pecos Closed Basin, West Texas And South-Central New Mexico, David Wilkins, Donald Currey

David E. Wilkins

The Trans-Pecos Closed Basin is a hydrographically closed region covering 20,000 km centered on Salt Basin, 160 km east of El Paso, Texas. Geomorphic and limnetic evidence have been used to identify four major highstands for Lake King during the last glacial maximum (LGM). Additional geomorphic features from a second, recently identified, paleolake, Lake Sacramento, have been found in the Beargrass subbasin, a nested subbasin approximately 75 km northwest of Salt Basin. Radiocarbon ages of the organic material in Lake King sediments date four abrupt climate changes and rapid lacustrine transgressions during the LGM with a quasi-periodicity of 2000 yr. …

Two-Photon Optogalvanic Spectra Of Argon: Odd Parity Rydberg States, Naveed Piracha, M. Baig, S. Khan, B. Suleman

Naveed K. Piracha

Extensive new data on the odd-parity, single-colour, two-photon optogalvanic spectra of argon in the visible region is reported using an excimer-pumped dye laser in conjunction with an argon discharge cell. The experimental technique enables us to record a pure two-photon spectrum in a region which is dominated by one-photon transitions. A large number of two-photon transitions, originating from the two metastable states [...] and [...] to the excited states of configurations [...] (J=0, 2) and [...] (J = 0 - 4) of argon, has been recorded and arranged into 10 Rydberg series. The interchannel interactions among the [...] and the …

Small Scale Electronic Transport In Diamond Microcrystals., M. Jaeger, S. Hyun, Anthony Day, M. Thorpe, B. Golding

Anthony Roy Day

The interpretation of electronic transport in polycrystalline diamond has proven difficult as a result of the disorder arising from physical and chemical inhomogeneities. We describe experimental methods, based on electron beam lithography, for studying transport in single crystallites grown by CVD on Si substrates. The electrical contacting process utilizes the flexibility of the scanning electron microscope to write metallic contacts to individual crystallites with lateral dimensions of a few μm. A detailed analysis of the current distribution in the crystals allows us to extract the electronic conductivity from arbitrarily shaped, faceted crystals.