Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

PDF

1991

Discipline
Institution
Keyword
Publication
Publication Type

Articles 31 - 60 of 1468

Full-Text Articles in Physical Sciences and Mathematics

Hepatic Microsomal N-Hydroxylation Of Aniline And 4-Chloroaniline By Rainbow Trout (Onchorhyncus Mykiss), Steven P. Bradbury, J. M. Dady, A. D. Hoffman, M. M. Voit, D. L. Olson Dec 1991

Hepatic Microsomal N-Hydroxylation Of Aniline And 4-Chloroaniline By Rainbow Trout (Onchorhyncus Mykiss), Steven P. Bradbury, J. M. Dady, A. D. Hoffman, M. M. Voit, D. L. Olson

Steven P. Bradbury

N-Hydroxylation of aniline and 4-chloroaniline was quantified in rainbow trout microsomal preparations using h.p.l.c.-liquid scintillation methods. Radioactive phenylhydroxylamine and 4-chlorophenylhydroxylamine metabolites were identified by co-elution with non-labelled standards. The method provided resolution of metabolite standards, and quantification of both N-hydroxylated metabolites was achieved without derivatization. The maximum velocities at 25 degrees C were 33.8 +/- 1.40 and 22.0 +/- 0.98 pmol/min per mg for aniline and 4-chloroaniline N-hydroxylation, respectively. The Km values were 1.0 +/- 0.11 and 0.8 +/- 0.11 mM for aniline and 4-chloroaniline N-hydroxylation, respectively. These activities were not induced by treatment of the trout with Aroclor 1254 …


Polymer Research In Austria. I: Introduction And The Facilities, Otto Vogl, Josef Schurz, Bernd Thrattnigg, Klaus Hummel, Wolfgang Daimler, Klaus Lederer Dec 1991

Polymer Research In Austria. I: Introduction And The Facilities, Otto Vogl, Josef Schurz, Bernd Thrattnigg, Klaus Hummel, Wolfgang Daimler, Klaus Lederer

Otto Vogl

No abstract provided.


Japan-U.S. Seminar On Polymer Synthesis, Otto Vogl, Hiroyuki Nishide Dec 1991

Japan-U.S. Seminar On Polymer Synthesis, Otto Vogl, Hiroyuki Nishide

Otto Vogl

No abstract provided.


Electron-Energy And –Angular Distributions In The Double Photoionization Of Helium, R. Wehlitz, Franz Heiser, Oliver Hemmers, B. Langer, A. Menzel, U. Becker Dec 1991

Electron-Energy And –Angular Distributions In The Double Photoionization Of Helium, R. Wehlitz, Franz Heiser, Oliver Hemmers, B. Langer, A. Menzel, U. Becker

Environmental Studies Faculty Publications

Photoelectron spectra of helium have been measured at different angles and at various energies above the double-ionization threshold up to 120 eV to investigate the behavior of the energy and angular distributions, of shake-off electrons. Both energy and angular distributions clearly show a U-shaped profile which turns to a flat curve near threshold pointing to a uniform intensity distribution over the kinetic energy for all angles in this excitation energy regime. Our results for the angular-distribution asymmetry parameter indicate qualitative agreement with theoretical predictions but fail to provide them quantitatively.


An Efficient Neural Algorithm For The Multiclass Problem, Rangachari Anand, Kishan Mehrotra, Chilukuri K. Mohan, Sanjay Ranka Dec 1991

An Efficient Neural Algorithm For The Multiclass Problem, Rangachari Anand, Kishan Mehrotra, Chilukuri K. Mohan, Sanjay Ranka

Electrical Engineering and Computer Science - Technical Reports

One connectionist approach to the classification problem, which has gained popularity in recent years, is the use of backpropagation-trained feed-forward neural networks. In practice, however, we find that the rate of convergence of net output error is especially low when training networks for multi-class problems. In this paper, we show that while backpropagation will reduce the Euclidean distance between the actual and desired output vectors, the difference between some of the components of these vectors will actually increase in the first iteration. Furthermore, the magnitudes of subsequent weight changes in each iteration are very small, so that many iterations are …


Efficient Maximum-Likelihood Soft-Decision Decoding Of Linear Block Codes Using Algorithm A, Yunghsiang S. Han, Carlos R.P. Hartmann, Chih-Chieh Chen Dec 1991

Efficient Maximum-Likelihood Soft-Decision Decoding Of Linear Block Codes Using Algorithm A, Yunghsiang S. Han, Carlos R.P. Hartmann, Chih-Chieh Chen

Electrical Engineering and Computer Science - Technical Reports

In this report we present a novel and efficient maximum-likelihood soft-decision decoding algorithm for linear block codes. The approach used here is to convert the decoding problem into a search problem through a graph which is a trellis for an equivalent code of the transmitted code. Algorithm A*, which uses a priority-first search strategy, is employed to search through this graph. This search is guided by an evaluation function f defined to take advantage of the information provided by the received vector and the inherent properties of the transmitted code. This function f is used to drastically reduce the search …


Parallel Divide And Conquer, Per Brinch Hansen Dec 1991

Parallel Divide And Conquer, Per Brinch Hansen

Electrical Engineering and Computer Science - Technical Reports

We develop a generic divide and conquer algorithm for a parallel tree machine. From the generic algorithm we derive balanced, parallel versions of quicksort and the fast Fourier transform by substitution of data types, variables and statements. The performance of these algorithms is analyzed and measured on a Computing Surface configured as a tree machine with distributed memory.


Do Hypercubes Sort Faster Than Tree Machines?, Per Brinch Hansen Dec 1991

Do Hypercubes Sort Faster Than Tree Machines?, Per Brinch Hansen

Electrical Engineering and Computer Science - Technical Reports

We develop a balanced, parallel quicksort algorithm for a hypercube and compare it with a similar algorithm for a binary tree machine. The performance of the hypercube algorithm is measured on a Computing Surface.


The Fast Fourier Transform, Per Brinch Hansen Dec 1991

The Fast Fourier Transform, Per Brinch Hansen

Electrical Engineering and Computer Science - Technical Reports

This tutorial discusses the fast Fourier transform, which has numerous applications in signal and image processing. The FFT computes the frequency components of a signal that has been sampled at n points in O( n log n) time. We explain the FFT and illustrate it by examples and Pascal algorithms. We assume that you are familiar with elementary calculus.


The Probe, Issue 117 - December 1991 Dec 1991

The Probe, Issue 117 - December 1991

The Probe: Newsletter of the National Animal Damage Control Association

THE PROBE
National Animal Damage Control Association
DECEMBER 1991
Evaluating Performance of the Soft-Catch® Coyote Trap
Calendar of Upcoming Events
President Bush Has Unique Style Of Animal Damage Control
Soft-Catch® Traps...
Animal Damage Control in the News:
It’s the “Gull War” at Kennedy International
Cyanide Baits May Be Allowed on BLM Land
Pocket Gopher Control Evaluation at Rogue River National Forest
“USA” Today Lists Predator Protection Tips
International Resolution Supports Regulated Trapping
Over Forty NADCA Members Attend 5th Eastern Wildlife Damage Control Conference
USDA Is Helping to Limit Rabies Outbreak In Texas
Wildlife Veterinarians Adopt Position Statement on Oral Rabies …


Practical Prefetching Techniques For Parallel File Systems, David Kotz, Carla Schlatter Ellis Dec 1991

Practical Prefetching Techniques For Parallel File Systems, David Kotz, Carla Schlatter Ellis

Dartmouth Scholarship

Parallel disk subsystems have been proposed as one way to close the gap between processor and disk speeds. In a previous paper we showed that prefetching and caching have the potential to deliver the performance benefits of parallel file systems to parallel applications. In this paper we describe experiments with practical prefetching policies, and show that prefetching can be implemented efficiently even for the more complex parallel file access patterns. We test these policies across a range of architectural parameters.


Caching And Writeback Policies In Parallel File Systems, David Kotz, Carla Schlatter Ellis Dec 1991

Caching And Writeback Policies In Parallel File Systems, David Kotz, Carla Schlatter Ellis

Dartmouth Scholarship

Improvements in the processing speed of multiprocessors are outpacing improvements in the speed of disk hardware. Parallel disk I/O subsystems have been proposed as one way to close the gap between processor and disk speeds. Such parallel disk systems require parallel file system software to avoid performance-limiting bottlenecks. We discuss cache management techniques that can be used in a parallel file system implementation. We examine several writeback policies, and give results of experiments that test their performance.


Remote Estimation Of The Diffuse Attenuation Coefficient In A Moderately Turbid Estuary, Richard P. Stumpf, Jonathan Pennock Dec 1991

Remote Estimation Of The Diffuse Attenuation Coefficient In A Moderately Turbid Estuary, Richard P. Stumpf, Jonathan Pennock

School of Marine Science and Ocean Engineering

Abstract

Solutions of the radiative transfer equation are used to derive relationships of water reflectance to the diffuse attenuation coefficient (K) in moderately turbid water (K > 0.5 m−1). Data sets collected from the NOAA AVHRR and in situ observations from five different dates confirm the appropriateness of these relationships, in particular the logistic equation. Values of K calculated from the reflectance data agree to within 60% of the observed values, although the reflectance derived using a more comprehensive aerosol correction is sensitive to chlorophyll concentrations greater than 50 μg L−1. Agreement between in situ and remote …


Surface Structure Of √3x√3r 30 Cl/Ni(111) Determined Using Low-Temperature Angle-Resolved-Photoemission Extended Fine Structure, Li-Qiong Wang, Z. Hussain, Z. Q. Huang, A. E. Schach Von Wittenau, Dennis W. Lindle, D. A. Shirley Dec 1991

Surface Structure Of √3x√3r 30 Cl/Ni(111) Determined Using Low-Temperature Angle-Resolved-Photoemission Extended Fine Structure, Li-Qiong Wang, Z. Hussain, Z. Q. Huang, A. E. Schach Von Wittenau, Dennis W. Lindle, D. A. Shirley

Chemistry and Biochemistry Faculty Research

A surface structural study of the √3 × √3 R30° Cl/Ni(111) adsorbate system was made using low-temperature angle-resolved photoemission extended fine structure. The experiments were performed along two emission directions, [111] and [110], and at two temperatures, 120 and 300 K. The multiple-scattering spherical-wave analysis determined that the Cl atom adsorbs in the fcc threefold hollow site, 1.837(8) Å above the first nickel layer, with a Cl-Ni bond length of 2.332(6) Å, and an approximate 5% contraction between the first and the second nickel layers (the errors in parentheses are statistical standard deviations only).


Photoemission And Electronic Structure Of Tungsten-Based Metallic Glasses And Alloys , M.A. Engelhardt, Sitaram Jaswal, David J. Sellmyer Dec 1991

Photoemission And Electronic Structure Of Tungsten-Based Metallic Glasses And Alloys , M.A. Engelhardt, Sitaram Jaswal, David J. Sellmyer

David Sellmyer Publications

The structure and electronic density of states of intertransition-metal glasses of the form TxW1-x have been investigated, where T=Cu, Ni, and Co. The film samples were prepared by cosputtering in a chamber with a rapidly rotating, water-cooled substrate. Experiments included x-ray diffraction and ultraviolet photoemission at photon energies of 21.2 and 40.8 eV, and electronic-structure calculations were performed with a self-consistent linear combination of muffin-tin-orbitals method. For the calculations the structures were simulated by either disordered crystalline or amorphous clusters of 60–64 atoms in a periodically extended supercell. The range of amorphous alloy formation was determined …


Design And Analysis Of Asynchronous Adders, Khalid Khanfar Dec 1991

Design And Analysis Of Asynchronous Adders, Khalid Khanfar

Masters Theses

The aim of this study is to come up with a fast adder suitable for use in self-timed subsystems. 7 adders were evaluated.

The findings from this study indicated that a Conditional Sum Adder (CSA) is the best candidate for high speed addition. One of the two resulting adders was given the name High Speed Conditional Sum Adder (HSCSA) .


Reductive Cleavage Of Cyclopentadienylmanganese Tricarbonyl, Mani S. Iyer Dec 1991

Reductive Cleavage Of Cyclopentadienylmanganese Tricarbonyl, Mani S. Iyer

Masters Theses

Since the isolation of ferrocene in 1951, it has been shown to behave like benzene and may be acylated, sulfonated, metalated, and arylated. Like benzene, it also resists hydrogenation.

Daniel Trifan and Louis Nicholas (1957) were the first to show that ferrocene can be smoothly degraded by lithium and ethylamine. The isolation of free cyclopentadienyl ion on hydrolysis of the reaction mixture indicates that the cleavage leads initially to cyclopentadienyl lithium salt. A similar procedure applied to cyclopentadienylmanganese tricarbonyl also resulted in the formation of cyclopentadienyl lithium salt. This, when added to ferrous chloride, gave ferrocene. This technique can be …


Specifying Interdatabase Dependencies In A Multidatabase Environment, Marek Rusinkiewicz, Amit P. Sheth, George Karabatis Dec 1991

Specifying Interdatabase Dependencies In A Multidatabase Environment, Marek Rusinkiewicz, Amit P. Sheth, George Karabatis

Kno.e.sis Publications

The problem of interdatabase dependencies and the effect they have on applications updating interdependent data are addressed. A model that allows specifications of constraints among multiple databases in a declarative fashion is proposed. The separation of the constraints from the application programs facilitates the maintenance of data constraints and allows flexibility in their implementation. It allows investigation of various mechanisms for enforcing the constraints, independently of the application programs. By grouping the constraints together, it is possible to check their completeness and discover possible contradictions among them. The concepts of polytransactions, which use interdatabase dependencies to generate a series of …


Selected Studies On Certain Iron Sandwich Complexes, Mashitah M. Yusoff Dec 1991

Selected Studies On Certain Iron Sandwich Complexes, Mashitah M. Yusoff

Masters Theses

In these studies, the synthesis of [2.3](1,3)cyclopentadiendoparacyclophane was attempted. Like ferrocene and [2.2]paracyclophane, it is expected to exhibit transannular π-electronic interaction throughout its molecular structure and therefore, one dimensional semiconductivity.

The preparation of dialkylferrocenes had resulted in complex inseparable mixtures. Due to the fluxional nature of its intermediates, their conversion to stable Diels-Alder adducts would facilitate analysis. In this project, certain Diels-Alder adducts of bis-cyclopentadienyliron dicarbonyl intermediates were prepared for analysis.

Very few transition metal complexes of pyrrole are currently known. [2.2](2,5)Pyrroloparacyclophane was perceived to be stable especially as a part of an iron sandwich complex. The final phase …


Structural, Depositional, And Diagenetic Controls On Reservoir Development: St. Peter Sandstone, Newaygo County, Michigan, Mark S. Caldwell Dec 1991

Structural, Depositional, And Diagenetic Controls On Reservoir Development: St. Peter Sandstone, Newaygo County, Michigan, Mark S. Caldwell

Masters Theses

Enhanced reservoir quality in the Middle Ordovician St. Peter Sandstone is observed in gas bearing zones in wells located on domal structures. Geometry and degree of this enhanced porosity development is the result of the interplay of structural, depositional, and diagenetic controls. An integrated subsurface study of the Woodville/Goodwell field area was performed in order to document controls on hydrocarbon accumulation.

Recurrent structural growth of domal features throughout the Paleozoic is well documented by isopach mapping. Burial and thermal history studies indicate that hydrocarbons were generated in Ordovician aged source rocks during late Devonian to early Mississippian time, and accumulated …


Resonant Electron Transfer And K-Shell Excitation Of Lithiumlike Projectiles In Collisions With Molecular Hydrogen, M. Anwar Kamal Dec 1991

Resonant Electron Transfer And K-Shell Excitation Of Lithiumlike Projectiles In Collisions With Molecular Hydrogen, M. Anwar Kamal

Masters Theses

An experimental investigation of resonant transfer and excitation (RTE) for collisions of Mg9+ (lithiumlike) projectile ions with a molecular hydrogen gas target has been made. The experimental cross sections for projectile K-shell x rays coincident with electron capture in the energy of 33- to 60-MeV are found to be in good agreement with theoretical RTE calculations. The present results confirm the agreement between experiment and theory which has been reported for RTE involving K-shell excitation for projectiles with atomic numbers between 9 and 92 incident on H2 and He targets.

Cross sections for total K-shell x-ray production and …


Recycling: Knowledge, Demographic & Motivational Factors Which Differentiate Behavior, David Ducoff Dec 1991

Recycling: Knowledge, Demographic & Motivational Factors Which Differentiate Behavior, David Ducoff

Masters Theses & Specialist Projects

This study focuses on motivation -Involved in recycling behavior among residents of Muhlenberg County, Kentucky. Knowledge of recycling and how it was acquired, and the variables of environmental concern, economic incentive and the peer pressure were compared so that behavior could be distinguished that separated recyclers from nonrecyclers. Talcott Parsons' work in action theory and George Homans' work in exchange theory provide the theoretical foundation for my study. The research was approached in a qualitatively based design with interviews of twenty area residents. Demographic factors of age, sex, religious affiliation, church attendance, education and income of respondents were solicited. In …


Sediment Characterization Of Coastal Lagoons And Bays, Mid-Atlantic Region, Maynard N. Nichols, C. M. Brouwer-Riel Dec 1991

Sediment Characterization Of Coastal Lagoons And Bays, Mid-Atlantic Region, Maynard N. Nichols, C. M. Brouwer-Riel

Reports

Sediment characterizations for the following lagoons and bays:

  • Great South Bay
  • Barnegat Bay
  • New Jersey Inland Bays, Great Sound
  • Delaware Inland Bays
  • Chincoteague Bay


The Prairie Naturalist Volume 23, No. 4. December 1991 Dec 1991

The Prairie Naturalist Volume 23, No. 4. December 1991

The Prairie Naturalist

Paul B. Kannowski, Editor

Nikki R. Seabloom, Assistant Editor

Douglas H. Johnson, Book Review Editor

CONTENTS

KENTUCKY BLUEGRASS RESPONSE TO BURNING: INTERACTIONS BETWEEN FIRE AND SOIL MOISTURE ▪ G. W. Blankespoor and B. S. Bich

FORAGE PRODUCTION AND USE ON BIGHORN SHEEP WINTER RANGE

FOLLOWING SPRING BURNING IN GRASSLAND AND PONDEROSA PINE HABITATS ▪ T. G. Easterly and K. J. Jenkins

SHORT-TERM MORTALITY OF SMALLMOUTH BASS CAUGHT DURING A LIVE-RELEASE TOURNAMENT AT LAKE OAHE, SOUTH DAKOTA ▪ J. J. Jackson and D. W. Willis

CRAYFISH IN SAND LAKE NATIONAL WILDLIFE REFUGE ▪ C. D. Dieter

PIPING PLOVERS NEST ON DRY …


Groundwater Levels In Nebraska, 1990, Gregory V. Steele, Perry B. Wigley Dec 1991

Groundwater Levels In Nebraska, 1990, Gregory V. Steele, Perry B. Wigley

Conservation and Survey Division

No abstract provided.


Preliminary Epidemiological Interpretation Of The Intrinsic And Extrinsic Factors Contributing To The Coverage And Participation Rates Of The Vaccination Program In Arssi, Ethiopia, Muchie Kidanu Dec 1991

Preliminary Epidemiological Interpretation Of The Intrinsic And Extrinsic Factors Contributing To The Coverage And Participation Rates Of The Vaccination Program In Arssi, Ethiopia, Muchie Kidanu

Electronic Theses and Dissertations

Many immunization programs in developing countries arr now undergoing a period of rapid utilization. Innovative strategies, such as immunization holidays, are being tried. Political commitment and enthusiasm are high. There is a strong desire by health professionals to protect the lives of many children from the untimely death and/or disability resulting from infectious diseases preventable by vaccination.

Evaluation of an immunization program can benefit other elements of the health system, particularly those that are not amenable to objective evaluation as immunization. In this case, immunization can serve as an indicator of the overall performance of the health system. The problems …


Formation Of Positronium In E+ + H- Collisions, Jack C. Straton, Richard J. Drachman Dec 1991

Formation Of Positronium In E+ + H- Collisions, Jack C. Straton, Richard J. Drachman

Physics Faculty Publications and Presentations

Cross sections for positronium formation by capture from the negative hydrogen ion are given. Orthogonalization corrections to the Coulomb (first-order) Born approximation (CBA) differential and total cross sections are calculated using approximate H- wave functions of both Löwdin [Phys. Rev. 90, 123 (1953)] and Chandrasekhar [Astrophys. J. 100, 176 (1944)]. The present calculation of the CBA cross sections using the post interaction for Löwdin’s wave function (LCBAPS) disagrees with the calculation of Choudhury, Mukherjee, and Sural (CMS) [Phys. Rev. A 33, 2358 (1986)], whereas our results using the prior interaction agree. Thus, where CMS found an order …


Convection In The Melt, John Bryant Drake Dec 1991

Convection In The Melt, John Bryant Drake

Doctoral Dissertations

A physical problem involving the melting/freezing of a phase-change material (PCM) is the applied setting of this research. The development of models that couple the partial differential equations for energy transport and fluid motion with phases of differing densities is a primary goal of the research. In Chapter 2, a general framework is developed for the formulation of conservation laws that admit interfaces. A notion of weak solution is developed and its relation with classical and other weak formulations is discussed. Conditions that hold across various kinds of interfaces are also developed. The formulation is examined for the conservation of …


Knowledge-Based Systems Approach For Offshore Safety Training, B. S. Lee, Venky Shankararaman Dec 1991

Knowledge-Based Systems Approach For Offshore Safety Training, B. S. Lee, Venky Shankararaman

Research Collection School Of Computing and Information Systems

A number of training methods has been used within the offshore industry to impart safety knowledge and safe operating skills. In this paper a Knowledge-Based Safety Training architecture is proposed. The architecture uses both expert system and hypertext methods and is also applicable to plants other than offshore platforms. Special attention is given to the types of knowledge dealt with in safety training and how to represent this knowledge and teach it using various teaching strategies.


Study Of The Heavy Fermion/Spin-Glass System, Ce1-X GdX Al3, Using 155Gd Mossbauer Spectroscopy, Nicholas G. Ruggiero Dec 1991

Study Of The Heavy Fermion/Spin-Glass System, Ce1-X GdX Al3, Using 155Gd Mossbauer Spectroscopy, Nicholas G. Ruggiero

Physics Theses & Dissertations

The magnetic properties of Ce1-xGdx.Al3 have been studied using 155Gd Mossbauer spectroscopy. It has been shown that the magnetic moments of the host GdAl3 are constrained to the basal plane. The magnetic properties of GdAl3 can best be described in the framework of RKKY theory. Prior studies of Ce1-xGdxAl3, have revealed complex magnetic behavior throughout the series. As observed with Mossbauer spectroscopy magnetic ordering occurs for x ≥ 0.5, though not at the reported spin glass temperatures. For x = 0.23 and x = 0.18, the …