Physical Sciences and Mathematics Commons^™

Near–Infrared Classification Spectroscopy: H–Band Spectra Of Fundamental Mk Standards, Michael R. Meyer, Suzan Edwards, Kenneth H. Hinkle, Stephen E. Strom

Astronomy: Faculty Publications

We present a catalog of H-band spectra for 85 stars of approximately solar abundance observed at a resolving power of 3000 with the KPNO Mayall 4 m Fourier Transform Spectrometer. The atlas covers spectral types O7M5 and luminosity classes IV as defined in the MK system. We identify both atomic and molecular indices and line ratios that are temperature and luminosity sensitive, allowing spectral classification to be carried out in the H-band. The line ratios permit spectral classification in the presence of continuum excess emission, which is commonly found in premain-sequence or evolved stars. We demonstrate that with …

A Late Cambrian Positive Carbon-Isotope Excursion In The Southern Appalachians: Relation To Biostratigraphy, Sequence Stratigraphy, Environments Of Deposition, And Diagenesis, Bosiljka Glumac, Kenneth R. Walker

Geosciences: Faculty Publications

A positive carbon-isotope excursion is recorded within the Upper Cambrian sedimentary succession in the southern Appalachians that consists of the Nolichucky Shale, the Maynardville Formation, and the Copper Ridge Dolomite. The lower part of the succession contains Aphelaspis zone fauna (Early Steptoean). The extensively dolomitized and poorly fossiliferous nature of the upper part of the succession precludes any detailed biostratigraphic determinations. Correlation with similar positive carbon-isotope excursions in coeval successions elsewhere suggests that this excursion represents a perturbation in the global cycling of carbon. Comparison of excursions at different localities in North America provides a means for the application of …

Near-Infrared Galaxy Counts To J And K ∼ 24 As A Function Of Image Size, Matthew A. Bershady, James D. Lowenthal, David C. Koo

Astronomy: Faculty Publications

We have used the Keck 10 m telescope to count objects as a function of image size in two high Galactic latitude Ðelds covering 1.5 arcmin2 and reaching 50% completeness depths of K \ 24 and J \ 24.5 for stellar sources. Our counts extend D1 mag deeper in K than those of surveys with other telescopes; complement other Keck surveys in the K-band that provide counts at comparable or shallower depths but that have not utilized image structure; and extend by several magnitudes the J-band counts from brighter surveys using smaller telescopes that cover larger areas. We Ðnd the …

Permitted Iron Emission Lines In The Classical T Tauri Star Dr Tauri, Georgina Beristain, Suzan Edwards, John Kwan

Astronomy: Faculty Publications

We present a study of permitted emission lines of Fe I and Fe II in the spectrum of the high-accretion rate classical T Tauri star DR Tau. Echelle spectra collected at the 4 m Mayall telescope at Kitt Peak National Observatory between 1988 and 1992 include four epochs with red spectral coverage (~5000-6800 Å) and three with blue spectral coverage (~4000-4950 Å). A total of 62 unblended Fe I and Fe II lines are identified, their profiles are examined, and ratios of line pairs that are sensitive to column density or temperature are analyzed.

The unblended Fe profiles exhibit a …

Ichnology Of Holocene Carbonate Eolianites On San Salvador Island, Bahamas: Diversity And Significance, H. Allen Curran, Brian White

Geosciences: Faculty Publications

Reprinted from: H. Allen Curran and John E. Mylroie (eds.), Proceedings of the 9th Symposium on the Geology of the Bahamas and Other Carbonate Regions: San Salvador, Bahamian Field Station

Computational Geometry Column 33, Joseph O'Rourke

Computer Science: Faculty Publications

Several recent SIGGRAPH papers on surface simplification are described.

Physical Dependence Of The Sensitivity And Room-Temperature Stability Of Auxge1-X Thin Film Resistive Thermometers On Annealing Conditions, Nathanael A. Fortune, Michael J. Graf, Keizo Murata

Physics: Faculty Publications

The reported nearly constant temperature sensitivity of appropriately annealed polycrystalline AuxGe1-x thin films at cryogenic temperatures would appear to make them promising materials for low mass, rapid thermal response resistive thermometers, but their adoption has been limited by difficulties in fabrication and uncertainties in annealing. In this work, we present a method of fabrication and annealing which allows control of the two most important parameters for these films: the room-temperature resistivity ρRT and the temperature sensitivity η(T), where η ≡ -d In R/d In T. We find that the dependence of ρRT on total anneal duration t for x≈0.18 is …

Far-Ultraviolet Spectra Of Starburst Galaxies: Stellar Population And The Kinematics Of The Interstellar Medium, Rosa M. Gonzalez Delgado, Claus Leitherer, Timothy Heckman, James D. Lowenthal, Henry C. Ferguson, Carmelle Robert

Astronomy: Faculty Publications

The far-ultraviolet spectra of the four starburst galaxies NGC 6090, Mrk 66, Mrk 1267, and IRAS 0833 + 6517 were observed with the Hopkins Ultraviolet Telescope during the Astro-2 mission. Additional data were obtained for IRAS 0833 + 6517 with the Goddard High-Resolution Spectrograph (GHRS) on the Hubble Space Telescope. We analyze the observations in terms of the stellar content and the kinematics of the interstellar medium, and we discuss the implications of these results for the interpretation of the ultraviolet spectra of high-redshift galaxies. Evolutionary synthesis models are used to constrain the star formation history from the absolute ultraviolet …

A Longitudinal Study Of Engineering Student Performance And Retention. V. Comparisons With Traditionally-Taught Students, Richard M. Felder, Gary Felder, E. Jacquelin Dietz

Physics: Faculty Publications

In a longitudinal study at North Carolina State University, a cohort of students took five chemical engineering courses taught by the same instructor in five consecutive semesters. The courses made extensive use of active and cooperative learning and a variety of other techniques designed to address a broad spectrum of learning styles. Previous reports on the study summarized the instructional methods used in the experimental course sequence, described the performance of the cohort in the introductory chemical engineering course, and examined performance and attitude differences between students from rural and urban backgrounds and between male and female students.1–4 This paper …

Comparison Of Recent Coral Life And Death Assemblages To Pleistocene Reef Communities: Implications For Rapid Faunal Replacement On Recent Reefs, Benjamin J. Greenstein, Lora A. Harris, H. Allen Curran

Geosciences: Faculty Publications

Marine ecologists and paleoecologists are increasingly recognizing that the Pleistocene and Holocene fossil record of coral reefs is the exclusive database from which an assessment of the long-term responses of reef communities to environmental perturbations may be obtained. The apparent persistence of coral communities in the face of intense fluctuations in sea level and sea surface temperature during glacial and interglacial stages of Pleistocene time is in marked contrast to dramatic fluctuations in reef community structure documented by short-term monitoring studies. We compared the taxonomic structure of live and dead coral communities on a modem patch reef currently undergoing a …

Isotope Geochemistry Of Proterozoic Talc Occurrences In Archean Marbles Of The Ruby Mountains, Southwest Montana, U.S.A, John B. Brady, John T. Cheney, Amy Larson Rhodes, Angela Vasquez, Chris Green, Mathieu Duvall, Ari Kogut, Lewis Kaufman, Dana Kovaric

Geosciences: Faculty Publications

Talc occurs as massive, economic deposits in upper amphibolite facies marbles of Archean age in southwestern Montana. Previous workers have demonstrated that the talc is a replacement of the marble that resulted from interaction with a large volume of fluid. δ18O (SMOW) values for dolomite and calcite range from 20-25‰ for the unaltered Archean marbles to as little as 8-10‰ in the talc deposits, suggesting that the metasomatic fluids had low δ18O values. In contrast, δ13C values for calcite and dolomite are similar for all samples (-2 to +2‰ PDB). Therefore, it is likely that the metasomatic fluids were oxygen-rich …

Bahamian Coral Reefs Yield Evidence Of A Brief Sea-Level Lowstand During The Last Interglacial, Brian White, H. Allen Curran, Mark A. Wilson

Geosciences: Faculty Publications

The growth of large, bank-barrier coral reefs on the Bahamian islands of Great Inagua and San Salvador during the last interglacial was interrupted by at least one major cycle of sea regression and transgression. The fall of sea level resulted in the development of a wave-cut platform that abraded early Sangamon corals in parts of the Devil's Point reef on Great Inagua, and produced erosional breaks in the reefal sequences elsewhere in the Devil's Point reef and in theCockburnTown reef on SanSalvador. Minor red caliche and plant trace fossils formed on earlier interglacial reefal rocks during the low stand. The …

Status Of Coral Reefs In The Northern Areas Of The Wider Caribbean, Judy Lang, Pedro Alcolado, Juan Pablo Carricart-Ganivet, Mark Chiappone, H. Allen Curran, Phil Dustan, Gudrun Gaudian, Francisco Geraldes, Steve Gittings, Robbie Smith, Wes Tunnell, Jean Wiener

Geosciences: Faculty Publications

Published on behalf of the (GCRMN) Global Coral Reef Monitoring Network by the Australian Institute of Marine Science

Ophiomorpha Nodosa In Estuarine Sands Of The Lower Miocene Calvert Formation At The Pollack Farm Site, Delaware, Molly F. Miller, H. Allen Curran, Ronald L. Martino

Geosciences: Faculty Publications

No abstract provided.

A Version Of A Theorem Of Dahlberg For The Subelliptic Dirichlet Problem, Luca Capogna, Nicola Garofalo, Duy Minh Nhieu

Mathematics Sciences: Faculty Publications

No abstract provided.

Illumination By Floodlights, William Steiger, Ileana Streinu

Computer Science: Faculty Publications

We consider three problems about the illumination of planar regions with floodlights of prescribed angles. Problem 1 is the decision problem: given a wedge W of angle φ ≤ π, n points p1 . . . . . pn in the plane and n angles α1 . . . . . αn such that ∑ni=1 αi ≤ θ, decide whether W can be illuminated by floodlights of angles α1 , . . . , αn placed in some order at the points p1 , . . . , pn and then rotated appropriately. We show that this problem is the …

Computational Geometry Column 34, Pankaj K. Agarwal, Joseph O'Rourke

Computer Science: Faculty Publications

Problems presented at the open-problem session of the 14th Annual ACM Symposium on Computational Geometry are listed.

Percentile Blobs For Image Similarity, Nicholas Howe

Computer Science: Faculty Publications

We present a new algorithm called PBSIM for computing image similarity, based upon a novel method of extracting bloblike features from images. In tests on a classification task using a data set of over 1000 images, PBSIM shows significantly higher accuracy than algorithms based upon color histograms, as well as previously reported results for another approach based upon bloblike features.

The Vertex-Edge Visibility Graph Of A Polygon, Joseph O'Rourke, Ileana Streinu

Computer Science: Faculty Publications

We introduce a new polygon visibility graph, the vertex-edge visibility graph GV E, and demonstrate that it encodes more geometric information about the polygon than does the vertex visibility graph GV. © 1998 Elsevier Science B.V.