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1995

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Articles 421 - 450 of 2193

Full-Text Articles in Physical Sciences and Mathematics

Safe Stratified Datalog With Integer Order Programs, Peter Revesz Sep 1995

Safe Stratified Datalog With Integer Order Programs, Peter Revesz

CSE Conference and Workshop Papers

Guaranteeing termination of programs on all valid inputs is important for database applications. Termination cannot be guaranteed in Stratified Datalog with integer (gap)-order programs on generalized databases because they express any Turing-computable function. This paper introduces a restriction of those programs that can express only computable queries. The restricted language has a high expressive power and a non-elementary data complexity.


Temperature Fluctuations In Photoionized Nebulae, J. B. Kingdon, Gary J. Ferland Sep 1995

Temperature Fluctuations In Photoionized Nebulae, J. B. Kingdon, Gary J. Ferland

Physics and Astronomy Faculty Publications

Recombination lines in gaseous nebulae frequently yield parent-ion abundances that are several times larger than abundances derived from forbidden lines. One possible explanation for this discrepancy is the presence of temperature fluctuations. We examine temperature fluctuations in model nebulae by utilizing Peimbert's t2 parameter. We have run large grids of models, varying the stellar temperature and the total hydrogen density. We consider two abundance sets: The first uses "typical" planetary nebulae abundances, while the second examines the effect of increasing the metals and grains by a factor of 3. We also consider both a constant density distribution and one …


An Improved Method For Determining And Characterizing Alignments Of Point-Like Features And Its Implications For The Pinacate Volcanic Field, Sonora, Mexico, Tim Lutz, J T. Gutmann Sep 1995

An Improved Method For Determining And Characterizing Alignments Of Point-Like Features And Its Implications For The Pinacate Volcanic Field, Sonora, Mexico, Tim Lutz, J T. Gutmann

Earth & Space Sciences Faculty Publications

We present an improved method for determining statistically significant alignments of pointlike features. One of the principal such methods now in use, the two-point azimuth method, depends on a homogeneous distribution of points over the region of interest. Modification of this approach by use of the relatively new statistical technique of kernel density estimation permits treatment of heterogeneous point distributions without introducing substantial dependence on choice of the grid employed in the test for significance of apparent preferred orientations. The improved method can selectively reveal alignments on different spatial scales and can suggest the locations of alignments as well as …


Large-Area Submillimeter Resolution Cdznte Strip Detector For Astronomy, James M. Ryan, John R. Macri, Mark L. Mcconnell, Brian K. Dann, M L. Cherry, T G. Guzik, F P. Doty, Boris A. Apotovsky, J F. Butler Sep 1995

Large-Area Submillimeter Resolution Cdznte Strip Detector For Astronomy, James M. Ryan, John R. Macri, Mark L. Mcconnell, Brian K. Dann, M L. Cherry, T G. Guzik, F P. Doty, Boris A. Apotovsky, J F. Butler

Space Science Center

We report the first performance measurements of a sub-millimeter CdZnTe strip detector developed as a prototype for space-borne astronomical instruments. Strip detector arrays can be used to provide two-dimensional position resolution with fewer electronic channels than pixellated arrays. Arrays of this type and other candidate technologies are under investigation for the position-sensitive backplane detector for a coded-aperture telescope operating in the range of 30 - 300 keV. The prototype is a 1.4 mm thick, 64 multiplied by 64 stripe CdZnTe array of 0.375 mm pitch in both dimensions, approximately one square inch of sensitive area. Pulse height spectra in both …


Comments On “Measurements Of 7Be And 210Pb In Rain, Snow, And Hall”, M. Baskaran Sep 1995

Comments On “Measurements Of 7Be And 210Pb In Rain, Snow, And Hall”, M. Baskaran

Environmental Science and Geology Faculty Research Publications

No abstract available


Remanence Measurements On Individual Magnetotactic Bacteria Using A Pulsed Magnetic Field, Ietje Penninga, Hendrik De Waard, Bruce M. Moskowitz, Dennis A. Bazylinski, Richard B. Frankel Sep 1995

Remanence Measurements On Individual Magnetotactic Bacteria Using A Pulsed Magnetic Field, Ietje Penninga, Hendrik De Waard, Bruce M. Moskowitz, Dennis A. Bazylinski, Richard B. Frankel

Physics

We describe pulsed-magnetic-field remanence measurements of individual, killed, undisrupted cells of three different types of magnetotactic bacteria. The measurement technique involved the observation of aligned, individual magnetotactic bacteria with a light microscope as they were subjected to magnetic pulses of increasing amplitude. We show that for MM cells, the hysteresis loop is square, with the coercive field variable from cell to cell. This is consistent with just two magnetization states for the single chain of magnetite particles. For MR and MMP cells, the hysteresis loops are not square, indicating that there are several different magnetization states, and that individual cells …


Controlled Biomineralization Of Magnetite (Fe3O4) And Greigite (Fe3S4) In A Magnetotactic Bacterium, Dennis A. Bazylinski, Richard B. Frankel, Brigid R. Heywood, Stephen Mann, John W. King, Percy L. Donaghay, Alfred K. Hanson Sep 1995

Controlled Biomineralization Of Magnetite (Fe3O4) And Greigite (Fe3S4) In A Magnetotactic Bacterium, Dennis A. Bazylinski, Richard B. Frankel, Brigid R. Heywood, Stephen Mann, John W. King, Percy L. Donaghay, Alfred K. Hanson

Physics

A slowly moving, rod-shaped magnetotactic bacterium was found in relatively large numbers at and below the oxic-anoxic transition zone of a semianaerobic estuarine basin. Unlike all magnetotactic bacteria described to date, cells of this organism produce single-magnetic-domain particles of an iron oxide, magnetite (Fe3O4), and an iron sulfide, greigite (Fe3O4), within their magnetosomes. The crystals had different morphologies, being arrowhead or tooth shaped for the magnetite particles and roughly rectangular for the greigite particles, and were coorganized within the same chain(s) in the same cell with their long axes along the chain …


Thindown In Biological 1-Hit Detectors: E. Coli B/R And Bs-1*, Zhang Chunxiang, Robert Katz Sep 1995

Thindown In Biological 1-Hit Detectors: E. Coli B/R And Bs-1*, Zhang Chunxiang, Robert Katz

Robert Katz Publications

According to the theory of Butts and Katz and the new radial dose distribution of Zhang et al., we have calculated inactivation cross sections for the heavy ion bombardment of E. Coli B/r and Bs-1 which w& in agreement with the measurements of Scliafer et made with ions from O to U at energies from 1.5 to 19.5 MeV/u. The data display "thindown", and the decrease in cross section with an increase in stopping power is accompanied by a decrease in energy of a bombarding ion. Following an earlier analysis of heavy ion bombardments of these E. Coli mutants with …


55. Hermann Janeschitz-Kriegl, Otto Vogl, Anton Schausberger Sep 1995

55. Hermann Janeschitz-Kriegl, Otto Vogl, Anton Schausberger

Otto Vogl

No abstract provided.


Table Of Contents Volume Six, Number Four, Fall 1995, Risk Editorial Board Sep 1995

Table Of Contents Volume Six, Number Four, Fall 1995, Risk Editorial Board

RISK: Health, Safety & Environment (1990-2002)

Table of contents for the journal RISK: Health, Safety & Environment (ISSN: 1073-8673)


An Architecture For A Camputs-Scale Wireless Mobile Internet, Douglas E. Comer, John C. Lin, Vincent F. Russo Sep 1995

An Architecture For A Camputs-Scale Wireless Mobile Internet, Douglas E. Comer, John C. Lin, Vincent F. Russo

Department of Computer Science Technical Reports

No abstract provided.


Proceedings Of The Mspls Spring '95 Workshop, Gerald Baumgartner, Vincent R. Russo Sep 1995

Proceedings Of The Mspls Spring '95 Workshop, Gerald Baumgartner, Vincent R. Russo

Department of Computer Science Technical Reports

No abstract provided.


Regular Algebraic Curve Segments (Ii) - Interpolation And Approximation, Guoliang Xu, Changrajit L. Bajaj Sep 1995

Regular Algebraic Curve Segments (Ii) - Interpolation And Approximation, Guoliang Xu, Changrajit L. Bajaj

Department of Computer Science Technical Reports

No abstract provided.


Regular Algebraic Curve Segments (I)- Definitions And Characteristics, Guoliang Xu, Changrajit L. Bajaj Sep 1995

Regular Algebraic Curve Segments (I)- Definitions And Characteristics, Guoliang Xu, Changrajit L. Bajaj

Department of Computer Science Technical Reports

No abstract provided.


Virtual Celluoid, Switch Staffs Sep 1995

Virtual Celluoid, Switch Staffs

SWITCH

The article is an analysis of the author’s research pertaining to films relating to or containing the concept of virtual reality. The author lists several films such as Johnny Mnemnonic, Virtuosity, The Net, and Disclosure and provides a brief synopsis and review of each movie. Each film explains the concept of virtual reality through differing plots and methods such as cyberspace, progressive software, and artificial intelligence. The author also gives their own insight into and ratings of the films, explaining what they think is the most relatable in terms of overall storyline as well as how realisticly the movie portrays …


Splines And Geometric Modeling, Chandrajit L. Bajaj, Susan Evans Sep 1995

Splines And Geometric Modeling, Chandrajit L. Bajaj, Susan Evans

Department of Computer Science Technical Reports

No abstract provided.


Distributed And Collaborative Synthetic Environments, Chandrajit L. Bajaj, Fausto Bernardini Sep 1995

Distributed And Collaborative Synthetic Environments, Chandrajit L. Bajaj, Fausto Bernardini

Department of Computer Science Technical Reports

No abstract provided.


S-To-P Broadcasting On Coarse-Grained Machines, Susanne E. Hambrusch, Ashfaq A. Khokhar, Yi Liu Sep 1995

S-To-P Broadcasting On Coarse-Grained Machines, Susanne E. Hambrusch, Ashfaq A. Khokhar, Yi Liu

Department of Computer Science Technical Reports

No abstract provided.


A Novel Design For A Small Retractable Cylindrical Mirror Analyzer, D.N. Mcilroy, Peter A. Dowben, A. Knop, E. Ruhl Sep 1995

A Novel Design For A Small Retractable Cylindrical Mirror Analyzer, D.N. Mcilroy, Peter A. Dowben, A. Knop, E. Ruhl

Peter Dowben Publications

In this paper we will review the performance of a “miniature” single pass cylindrical mirror analyzer (CMA) which we have used successfully in a variety of experiments. The underlying premise behind this CMA design was to minimize spatial requirements while maintaining an acceptable level of instrumental resolution. While we are presenting the results of a single pass cylindrical mirror analyzer, improvements on the present design, such as going to a double pass design, will undoubtedly improve the instrumental resolution.


A Novel Design For A Small Retractable Cylindrical Mirror Analyzer, D.N. Mcilroy, Peter A. Dowben, A. Knop, E. Ruhl Sep 1995

A Novel Design For A Small Retractable Cylindrical Mirror Analyzer, D.N. Mcilroy, Peter A. Dowben, A. Knop, E. Ruhl

Peter Dowben Publications

In this paper we will review the performance of a “miniature” single pass cylindrical mirror analyzer (CMA) which we have used successfully in a variety of experiments. The underlying premise behind this CMA design was to minimize spatial requirements while maintaining an acceptable level of instrumental resolution. While we are presenting the results of a single pass cylindrical mirror analyzer, improvements on the present design, such as going to a double pass design, will undoubtedly improve the instrumental resolution.


The Prairie Naturalist Volume 27, No.3. September 1995 Sep 1995

The Prairie Naturalist Volume 27, No.3. September 1995

The Prairie Naturalist

SONGBIRD RESPONSES TO SAGEBRUSH REMOVAL IN A HIGH ELEVATION SAGEBRUSH STEPPE ECOSYSTEM ▪ L L Kerley and S. H Anderson

THE AVIFAUNA OF REMNANT TALLGRASS PRAIRIE NEAR BOULDER, COLORADO ▪ C E Bock, J. H Bock, and B. C Bennett

SHORT -TERM RESPONSES OF SMALL MAMMALS TO AUTUMN FIRE IN TALLGRASS PRAIRIE ▪ B.R. McMillan, D. E Brillhart, G A. Kaufman, and D. W. Kaufman

DIVERGENT SELECTION FOR SEED MASS IN FOXTAIL DALEA ▪ R. Bortnem and A. Boe

NOTES

American Woodcock Use of a Nest Box ▪ D.L. Bergman and J. M. Bergman

BOOK REVIEWS

Iowa's Vascular Plants ▪ …


The Probe, Issue # 158 - September 1995 Sep 1995

The Probe, Issue # 158 - September 1995

The Probe: Newsletter of the National Animal Damage Control Association

Wildlife relocation impacts both animals and humans
Massachusetts Court Okays Some Use of "Soft-Hold" Traps
Cousin of Lyme Disease?
Coyotes Continue as Overwhelming Predators Responsible for U.S. Sheep & Lamb Losses
Video Review: "Bat-Free Belfries: A Guide to Bat-Proofing." Produced by Pennsylvania State University, College of Agricultural Services. Content developed by Lisa M. Willias-Whitmer and Margaret C. Brittingham
FMC Corp. Predator Control Brochure
New Rabies Vaccine
Evaluation of the Super YardGard Electronic Device for Repelling Whitetailed Deer
Wolf Damage Control Program Sued


Anisotropic Anharmonicity Of Lattice And Molecular Vibrations Of 1,2,4,5 Tetrabromobenzene Determined By Piezomodulated Raman Spectroscopy, K.M. White, Craig J. Eckhardt Sep 1995

Anisotropic Anharmonicity Of Lattice And Molecular Vibrations Of 1,2,4,5 Tetrabromobenzene Determined By Piezomodulated Raman Spectroscopy, K.M. White, Craig J. Eckhardt

Craig J. Eckhardt Publications

Strain-induced coupling constants for the anharmonicity of Raman-active lattice and certain molecular modes of vibration in 1,2,4,5-tetrabromobenzene (TBB) crystals have been determined using piezomodulated Raman spectroscopy. These constants, which are directly related to the first anharmonic term in the potential energy expansion for lattice dynamical calculations, are a quantitative measurement of the modal anharmonicities in the TBB molecular crystal. Application of uniaxial stress in the experiments permits the anisotropy of the anharmonicity to be determined as well as its magnitude. The TBB lattice modes are significantly coupled by the induced strains and the effects of coupling were observed to be …


Stress Evolution During The Growth Of Ultrathin Layers Of Iron And Iron Silicide On Si(111), D. Sander, Axel Enders, J. Kirschner Sep 1995

Stress Evolution During The Growth Of Ultrathin Layers Of Iron And Iron Silicide On Si(111), D. Sander, Axel Enders, J. Kirschner

Axel Enders Publications

Using a simple optical deflection technique, we measured continuously the mechanical stress during the growth of Fe films of 0.1–1.5 nm thickness on Si(111) in ultrahigh vacuum (UHV). The stress versus coverage dependence is discussed in view of the different growth modes during the various stages of Fe deposition. The deposition of up to 0.3 nm Fe induces a compressive stress of -1 N/m. We assign this stress to the formation of a reactive Fe–Si interface layer with a silicide-like structure. Subsequent Fe deposition at 300 K leads to a small tensile stress of 0.7 N/m, whereas the deposition at …


Implementation Of A Campuswide Distributed Mass Storage Service: The Dream Versus Reality, Betty Jo Armstead, Stephen Prahst Sep 1995

Implementation Of A Campuswide Distributed Mass Storage Service: The Dream Versus Reality, Betty Jo Armstead, Stephen Prahst

Armstead Publications and Presentations

In 1990, a technical team at NASA Lewis Research Center, Cleveland, Ohio, began defining a Mass Storage Service to provide long-term archival storage, short-term storage for very large files, distributed Network File System access, and backup services for critical data that resides on workstations and personal computers. Because of software availability and budgets, the total service was phased in over 3 years. During the process of building the service from the commercial technologies available, our Mass Storage Team refined the original vision and learned from the problems and mistakes that occurred. We also enhanced some technologies to better meet the …


A Comparative Evaluation Of Voice Versus Keypad Input For Manipulating Electronic Technical Data For Flight Line Maintenance Technicians, David A. Chapman, James R. Simmons Sep 1995

A Comparative Evaluation Of Voice Versus Keypad Input For Manipulating Electronic Technical Data For Flight Line Maintenance Technicians, David A. Chapman, James R. Simmons

Theses and Dissertations

Interactive Electronic Technical Manuals will soon become a requirement for aircraft maintenance technicians. An important aspect in their development is the selection of an input device that will enhance, rather than impede, technician performance. The purpose of this thesis was to evaluate two types of input devices that can he used: a voice recognition input and a keypad input. Studies to date have evaluated the superiority of digital data over paper data, and advantages of using a Head Mounted Display Device over a flat screen laptop computer. No research has evaluated the input device. An experiment was conducted to determine …


Air Force Materiel Command (Afmc) Modeling, Simulation, And Analysis (Ms&A) Interactive Database, Timothy J. Wagner Sep 1995

Air Force Materiel Command (Afmc) Modeling, Simulation, And Analysis (Ms&A) Interactive Database, Timothy J. Wagner

Theses and Dissertations

This study develops a high level, unifying taxonomy for Modeling, Simulation, and Analysis (MS&A) products for the Air Force Materiel Command (AFMC). AFMC is concerned that limited resources are being expended on duplicative MS&A efforts. No mechanism exists that would confirm or deny this concern, so it was suggested that a database could be developed to catalog and track AFMC's MS&A inventory. First, it was necessary to determine the information that a decision maker needs to select a suitable MS&A product. Potential traits and characteristics were identified through review of current regulatory guidance, interviews with MS&A users, and a study …


Collisional Dynamics Of The Rubidium 52P Levels, Matthew D. Rotondaro Sep 1995

Collisional Dynamics Of The Rubidium 52P Levels, Matthew D. Rotondaro

Theses and Dissertations

The collisional dynamics of the 52P levels in rubidium has been examined using steady-state laser absorption and spectrally-resolved laser induced fluorescence techniques. State-to-state cross-sections for energy transfer between Zeeman split levels ranged from 16-248 °A2 for collisions with nitrogen and rare gases. These energy transfer cross-sections exhibit a significant dependence on (J,mj) state and certain symmetry relationships are demonstrated. A sub-Doppler spectrum of the Zeeman split levels indicating the isotopic shift in the D1 line of 106 ± 35 was obtained using laser saturation spectroscopy.


Vr Projects, P.D. Quick Sep 1995

Vr Projects, P.D. Quick

SWITCH

A description of three three projects having to do with virtual reality. The first is the Nanomanipulator, developed at the University of North Carolina Chapel Hill Department of Computer Science in conjunction with the UCLA Department of Chemistry in 1991. It is a machine that allows the user to interact with microscopic particles previously only visible in 2D from an electron microscope. The second project, The Augmented Reality Project, also developed at the Chapel Hill Department of Computer Science. This device used ultrasound images to be placed over a body allowing the user to see inside of it. The final …


Vrware Beware: Vr At Siggraph, P.D. Quick Sep 1995

Vrware Beware: Vr At Siggraph, P.D. Quick

SWITCH

The article uses the author’s experiences from the event of Siggraph ‘95 to comment on upcoming products using virtual or augmented reality. The article includes further discussion on the products’ effects on the psychology and physiology of consumers. Some examples include the “i-Glasses” from Virtual I/O, the “Smart Model” from Multigen, as well as the nanomanipulator created by University of North Carolina Chapel Hill Department of Computer Science, and the Phobia Project developed by the Georgia Tech Graphics Visualization and Usability Center. The article also covers not only the products of this event, but also the courses, panels, papers, and …