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1997

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Articles 631 - 660 of 2472

Full-Text Articles in Physical Sciences and Mathematics

Activation In The Comptel Double-Scattering Gamma-Ray Telescope, D Morris, Mark L. Mcconnell, James M. Ryan, R Diehl, U Oberlack, V Schonfelder, M Varendorff, G Weidenspointer, H Deboer, K Bennett Jul 1997

Activation In The Comptel Double-Scattering Gamma-Ray Telescope, D Morris, Mark L. Mcconnell, James M. Ryan, R Diehl, U Oberlack, V Schonfelder, M Varendorff, G Weidenspointer, H Deboer, K Bennett

Space Science Center

Abstract-The COMPTEL gamma-ray telescope has been operating in low Earth orbit for six years, since the launch of the Compton Gamma-Ray Observatory in April 1991. Comparisons of data for different orbits and epochs show evidence of activation on time scales from minutes (27Mg, q,2=9.5 min) to years C2Na, q&.58 yr). The activation is correlated with both the orbital altitude and solar cosmic-ray modulation. Because it requires coincident measurements in two different detectors, COMPTEL is most susceptible to instrumental background events in which two or more photons are produced simultaneously.

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Recurrent Geomagnetic Storms And Relativistic Electron Enhancements In The Outer Magnetosphere: Istp Coordinated Measurements, D N. Baker, X Li, Niescja E. Turner, J H. Allen, L F. Bargatze, J B. Blake, R B. Sheldon, H E. Spence, R D. Belian, G D. Reeves, S G. Kanekal, B Klecker, R P. Lepping, K Ogilvie, R A. Mewaldt, T Onsager, H J. Singer, G Rostoker Jul 1997

Recurrent Geomagnetic Storms And Relativistic Electron Enhancements In The Outer Magnetosphere: Istp Coordinated Measurements, D N. Baker, X Li, Niescja E. Turner, J H. Allen, L F. Bargatze, J B. Blake, R B. Sheldon, H E. Spence, R D. Belian, G D. Reeves, S G. Kanekal, B Klecker, R P. Lepping, K Ogilvie, R A. Mewaldt, T Onsager, H J. Singer, G Rostoker

Physics and Astronomy Faculty Research

New, coordinated measurements from the International Solar-Terrestrial Physics (ISTP) constellation of spacecraft are presented to show the causes and effects of recurrent geomagnetic activity during recent solar minimum conditions. It is found using WIND and POLAR data that even for modest geomagnetic storms, relativistic electron fluxes are strongly and rapidly enhanced within the outer radiation zone of the Earth's magnetosphere. Solar wind data are utilized to identify the drivers of magnetospheric acceleration processes. Yohkoh solar soft X-ray data are also used to identify the solar coronal holes that produce the high-speed solar wind streams which, in turn, cause the recurrent …

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Afec: An Adaptive Forward Error- Correction Protocol And Its Analysis, Kihong Park Jul 1997

Afec: An Adaptive Forward Error- Correction Protocol And Its Analysis, Kihong Park

Department of Computer Science Technical Reports

No abstract provided.

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General Pattern Matching, Alberto Apostolico Jul 1997

General Pattern Matching, Alberto Apostolico

Department of Computer Science Technical Reports

No abstract provided.

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The Contour Spectrum, Chandrajit L. Bajaj, Valerio Pasucci, Daniel R. Schikore Jul 1997

The Contour Spectrum, Chandrajit L. Bajaj, Valerio Pasucci, Daniel R. Schikore

Department of Computer Science Technical Reports

No abstract provided.

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Neutron Resonance Spectroscopy Of 107ag, And 109ag, L Y. Lowie, J D. Bowman, Bret E. Crawford, P P J. Delheij, T Haseyama, J N. Knudsen, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, Y-F Yen, V W. Yuan Jul 1997

Neutron Resonance Spectroscopy Of 107ag, And 109ag, L Y. Lowie, J D. Bowman, Bret E. Crawford, P P J. Delheij, T Haseyama, J N. Knudsen, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, Y-F Yen, V W. Yuan

Physics and Astronomy Faculty Publications

Parity violation has been observed in a number of previously unreported neutron resonances in silver. Analysis of these parity violation data requires improved neutron resonance spectroscopy. The neutron total cross section for natural silver was measured for En=10–800 eV with the time-of-flight method at the Los Alamos Neutron Scattering Center. The neutron capture reaction was studied with both a natural silver target and a highly enriched sample (98.29%) of 107Ag. A total of 38 previously unreported resonances were observed. The combination of the two measurements allowed assignment of the newly observed resonances to 107Ag or to …

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Catches Of Humpback And Other Whales From Shore Stations At Moss Landing And Trinidad, California, 1919-1926, Phillip Clapham, Stephen Leatherwood, Isidore Szczepaniak, Robert L. Brownell Jr. Jul 1997

Catches Of Humpback And Other Whales From Shore Stations At Moss Landing And Trinidad, California, 1919-1926, Phillip Clapham, Stephen Leatherwood, Isidore Szczepaniak, Robert L. Brownell Jr.

United States Department of Commerce: Staff Publications

Logbook data from California shore whaling stations at Moss Landing (1919-1922 and 1924) and Trinidad (1920 and 1922-1926) are analyzed. The logs for the two stations record the taking of 2,111 whales, including 1,871 humpbacks, 177 fin whales, 26 sei whales, 3 blue whales, 12 sperm whales, 7 gray whales, 1 right whale, 1 Baird’s beaked whale, and 13 whales of unspecified type (probably humpbacks). Most whales were taken from spring to autumn, but catches were made in all months of some years. The sex ratios of humpback, fin, and sei whales (the three species with sufficient sample sizes to …

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Core Scattering Of Stark Wave Packets, M. L. Naudeau, C. I. Sukenik, P. H. Bucksbaum Jul 1997

Core Scattering Of Stark Wave Packets, M. L. Naudeau, C. I. Sukenik, P. H. Bucksbaum

Physics Faculty Publications

We investigate the wave packet dynamics of electrons bound in the nonseparable potential of cesium in a static electric field using time-domain Ramsey interferometry. Specially shaped wave packets with low radial dispersion enable us to view the interaction between the wave packet and the atomic core. Experiments in cesium, together with quantum defect calculations of cesium and hydrogen, demonstrate changes in the motion and shape of these wave packets due to core scattering.

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An Analysis Of Tropical Transport: Influence Of The Quasi-Biennial Oscillation, Eugene C. Cordero, S. Randolph Kawa, Mark R. Schoeberl Jul 1997

An Analysis Of Tropical Transport: Influence Of The Quasi-Biennial Oscillation, Eugene C. Cordero, S. Randolph Kawa, Mark R. Schoeberl

Eugene C. Cordero

An analysis of over 4 years of Upper Atmosphere Research Satellite (UARS) measurements of CH4, HF, O3, and zonal wind are used to study the influence of the quasi-biennial oscillation (QBO) on constituent transport in the tropics. At the equator, spectral analysis of the Halogen Occultation Experiment (HALOE) and Microwave Limb Sounder (MLS) observations reveals QBO signals in constituent and temperature fields at altitudes between 20 and 45 km. Between these altitudes, the location of the maximum QBO amplitude roughly corresponds with the location of the largest vertical gradient in the constituent field. Thus, at 40 …

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Quality Of Service Provision In Noncooperative Network Environments, Kihong Park, Meera Sitharam, Shaogang Chen Jul 1997

Quality Of Service Provision In Noncooperative Network Environments, Kihong Park, Meera Sitharam, Shaogang Chen

Department of Computer Science Technical Reports

No abstract provided.

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Idealwise Algebraic Independence For Elements Of The Completion Of A Local Domain, William Heinzer, Christel Rotthaus, Sylvia Wiegand Jul 1997

Idealwise Algebraic Independence For Elements Of The Completion Of A Local Domain, William Heinzer, Christel Rotthaus, Sylvia Wiegand

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Over the past forty years many examples in commutative algebra have been constructed using the following principle: Let k be a field, let S k[xl Xn]x,xn) be a localized polynomial ring over k, and let a be an ideal in the completion S of S such that the associated prims of a are in the generic formal fiber of S; that is, p N S (0) for each p Ass(S/a):. Then S embeds in S/a, the fraction field Q(S) of S embeds in the fraction ring of S/a, and for certain choices of a, the intersection D Q(S) f3 (S/a) …

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Auslander Systems, K. N. Haddad, Aimee S. A. Johnson Jul 1997

Auslander Systems, K. N. Haddad, Aimee S. A. Johnson

Mathematics & Statistics Faculty Works

The authors generalize the dynamical system constructed by J. Auslander in 1959, resulting in perhaps the simplest family of examples of minimal but not strictly ergodic systems. A characterization of unique ergodicity and mean-L-stability is given. The new systems are also shown to have zero topological entropy and fail to be weakly rigid. Some results on the set of idempotents in the enveloping semigroup are also achieved.

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The Probe, Issue 178 - July 1997 Jul 1997

The Probe, Issue 178 - July 1997

The Probe: Newsletter of the National Animal Damage Control Association

CONTENTS:
Michigan Bear Referendum
CALENDAR OF UPCOMING EVENTS
Brown Tree Snakes Plague Guam
ADC on the Web (extracted from postings to the WDAMAGE Bulletin Board)
Teens Arrested for Animal Rights Activity
Study Looks At Coyote Effects on Pronghorn
Sportsmen Protest 'Alliance for Animals' Meeting
Legislative Update
Fund for Animals Seeks USFWS Grant
Diverse Wildlife Problems in Texas

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The Probe, Issue 178 - July 1997 Jul 1997

The Probe, Issue 178 - July 1997

The Probe: Newsletter of the National Animal Damage Control Association

Contents:
Michigan Bear Referendum
Calendar of Upcoming Events
Brown Tree Snakes to Continue to Plague Guam
ADC on the Web (extracted from postings to the WDAMAGE Bulletin Board)
Teens Arrested for Animal Rights Activity
Sportsmen Protest 'Alliance for Animals' Meeting
Study Looks At Coyote Effects on Pronghorn
Legislative Updates: Arizona, California, Colorado, Wisconsin
Fund for Animals Seeks USFWS Grant
Diverse Wildlife Problems in Texas

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Canadian Cooperative Wildlife Health Center Newsletter, Volume 4-3, Summer 1997 Jul 1997

Canadian Cooperative Wildlife Health Center Newsletter, Volume 4-3, Summer 1997

Canadian Cooperative Wildlife Health Centre: Newsletters and Publications

CCWHC Newsletter on the World Wide Web
Five-Year Review of the CCWHC
Centre for Coastal Health Moves to Nanaimo
Newcastle Disease in Cormorants, California, USA-May 1997
Chronic Wasting Disease of Wild Deer
Salmonellosis in Herons, Gannet
Probable Newcastle Disease in a cormorant
Neoplasm in Eiders
Birthing Death in a Harbour Porpoise
Low Prevalence of Neoplasia in St. Lawrence River Eels
Mortality at a Bird Feeder
Suspected Teflton Toxicosis in Songbirds
Suspected Avitrol Poisoning of Non-target Species
Forensic (medico-legal) Examinations
Mortality of Porpoises in British Columbia
Predator Attacks in British Columbia
Spring Botulism

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Critical Issues For Understanding Particle Acceleration In Impulsive Solar Flares, James A. Miller, Peter J. Cargill, A. Gordon Emslie, Gordon D. Holman, Brian R. Dennis, Ted N. La Rosa, Robert M. Winglee, Stephen G. Benka, S. Tsuneta Jul 1997

Critical Issues For Understanding Particle Acceleration In Impulsive Solar Flares, James A. Miller, Peter J. Cargill, A. Gordon Emslie, Gordon D. Holman, Brian R. Dennis, Ted N. La Rosa, Robert M. Winglee, Stephen G. Benka, S. Tsuneta

Faculty Articles

This paper, a review of the present status of existing models for particle acceleration during impulsive solar flares, was inspired by a week-long workshop held in the Fall of 1993 at NASA Goddard Space Flight Center. Recent observations from Yohkoh and the Compton Gamma Ray Observatory, and a reanalysis of older observations from the Solar Maximum Mission, have led to important new results concerning the location, timing, and efficiency of particle acceleration in flares. These are summarized in the first part of the review. Particle acceleration processes are then discussed, with;particular emphasis on new developments in stochastic acceleration by magnetohydrodynamic …

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Monte Carlo Study Of The Square-Lattice Annealed Ising Model On Percolating Clusters, P. D. Scholten, Miron Kaufman Jul 1997

Monte Carlo Study Of The Square-Lattice Annealed Ising Model On Percolating Clusters, P. D. Scholten, Miron Kaufman

Physics Faculty Publications

Simulations of an Ising q-state Pods model which is equivalent to the Ising model on annealed percolation clusters are used to determine the phase diagram of the model in two dimensions. Three topologically different phase diagrams are obtained: (i) for q=2, there are two critical Ising lines meeting at T=0 at the four-state Potts critical point; (ii) for 24, the Ising:critical line intersects a Line of first-order transitions at a critical end point.

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Quantum Manifestations Of Bifurcations Of Closed Orbits In The Photodetachment Cross Section Of H- In Parallel Fields, Aaron D. Peters, Charles Jaffé, J. Gao, John B. Delos Jul 1997

Quantum Manifestations Of Bifurcations Of Closed Orbits In The Photodetachment Cross Section Of H- In Parallel Fields, Aaron D. Peters, Charles Jaffé, J. Gao, John B. Delos

Arts & Sciences Articles

In the preceding paper, we showed that the semiclassical approximation diverges at a bifurcation, and that this divergence coincides with the passage of a focused cusp through the origin. Here we obtain a wave function in the vicinity of this cusp, and we use that wave function to eliminate the divergences in the photodetachment cross section. To describe the focused cusp, we first discuss the wave function of an ordinary two-dimensional (nonfocused) cusp. This wave function is known as a Pearcey function, and it has been studied extensively. Then we show how the formulas that lead to the Pearcey function …

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Physical Parameterization Of Stellar Spectra: The Neural Network Approach, Coryn A.L. Bailer-Jones, Ted Von Hippel, Mike Irwin, Gerard Gilmore Jul 1997

Physical Parameterization Of Stellar Spectra: The Neural Network Approach, Coryn A.L. Bailer-Jones, Ted Von Hippel, Mike Irwin, Gerard Gilmore

Publications

We present a technique which employs artificial neural networks to produce physical parameters for stellar spectra. A neural network is trained on a set of synthetic optical stellar spectra to give physical parameters (e.g. Teff, log g, [M/H]). The network is then used to produce physical parameters for real, observed spectra. Our neural networks are trained on a set of 155 synthetic spectra, generated using the spectrum program written by Gray (Gray & Corbally 1994, Gray & Arlt 1996). Once trained, the neural network is used to yield Teff for over 5000 B–K spectra extracted from a set of photographic …

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Native Vegetation Handbook For The Shire Of Beverley, Rod Safstrom Jul 1997

Native Vegetation Handbook For The Shire Of Beverley, Rod Safstrom

Native vegetation handbook series

This Handbook is one of a series covering the agricultural region of Western Australia. The Handbook aims to assist the development of sustainable farming systems which combine agricultural production and nature conservation. Information is provided on the natural resources of the Shire of Beverley, including the existing vegetation, drainage systems and soils. Problems in managing these resources are described and community initiatives to tackle the problems are summarised.

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Native Vegetation Handbook For The Shire Of Pingelly, Rod Safstrom Jul 1997

Native Vegetation Handbook For The Shire Of Pingelly, Rod Safstrom

Native vegetation handbook series

This Handbook is one of a series covering the agricultural region of Western Australia. The Handbook aims to assist the development of sustainable farming systems which combine agricultural production and nature conservation. Information is provided on the natural resources of the Shire of Pingelly, including the existing vegetation, drainage systems and soils. Problems in managing these resources are described and community initiatives to tackle the problems are summarised. It is hoped that this Handbook will contribute to the long term viability of the agricultural landscape and the conservation of native vegetation within the Shire.

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Using The Simplex Code To Construct Relative Difference Sets In 2-Groups, James A. Davis, Surinder K. Sehgal Jul 1997

Using The Simplex Code To Construct Relative Difference Sets In 2-Groups, James A. Davis, Surinder K. Sehgal

Department of Math & Statistics Faculty Publications

Relative Difference Sets with the parameters (2a, 2b, 2a, 2a-b) have been constructed many ways (see [2], [3], [5], [6], and [7] for examples). This paper modifies an example found in [1] to construct a family of relative difference sets in 2-groups that gives examples for b = 2 and b = 3 that have a lower rank than previous examples. The Simplex code is used in the construction.

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High Resolution Oi (630 Nm) Image Measurements Of Fregion Depletion Drifts During The Guara Campaign, Michael J. Taylor, J. Labelle, J. A.H. Sobral Jul 1997

High Resolution Oi (630 Nm) Image Measurements Of Fregion Depletion Drifts During The Guara Campaign, Michael J. Taylor, J. Labelle, J. A.H. Sobral

All Physics Faculty Publications

A high performance, all‐sky, imaging system has provided data on the evolution and drift motions of F‐region depletions above the magnetic dip equator at Alcântara, Brazil, (2.3°S, 44.5°W). Monochromatic images of depletions in the OI(630 nm) nightglow were recorded on eight nights during 1‐16 October, 1994, as part of the Guará campaign. The drift motions of the depletions were typically 80–100 m/s eastward prior to local midnight and reduced to a minimum of ∼30–50 m/s in the morning hours, in accord with previous observations. However, on October 2–3 and 12–13 the depletions were observed to reverse direction for ∼60–90 min, …

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Effects Of Spatial Resolution And Landscape Structure On Land Cover Characterization, Wenli Yang Jul 1997

Effects Of Spatial Resolution And Landscape Structure On Land Cover Characterization, Wenli Yang

Department of Geography: Dissertations, Theses, and Student Research

This dissertation addressed problems in scaling, problems that are among the main challenges in remote sensing. The principal objective of the research was to investigate the effects of changing spatial scale on the representation of land cover. A second objective was to determine the relationship between such effects, characteristics of landscape structure and scaling procedures. Four research issues related to spatial scaling were examined. They included: 1) the upscaling of Normalized Difference Vegetation Index (NDVI); 2) the effects of spatial scale on indices of landscape structure; 3) the representation of land cover databases at different spatial scales; and 4) the …

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Relative Motion Between The Caribbean And North American Plates And Related Boundary Zone Deformation From A Decade Of Gps Observations, Timothy H. Dixon, Frederic Farina, Charles Demets, Pamela Jansma, Paul Mann, Eric Calais Jul 1997

Relative Motion Between The Caribbean And North American Plates And Related Boundary Zone Deformation From A Decade Of Gps Observations, Timothy H. Dixon, Frederic Farina, Charles Demets, Pamela Jansma, Paul Mann, Eric Calais

School of Geosciences Faculty and Staff Publications

Global Positioning System (GPS) measurements in 1986, 1994, and 1995 at sites in Dominican Republic, Puerto Rico, Cuba, and Grand Turk define the velocity of the Caribbean plate relative to North America. The data show eastward motion of the Caribbean plate at a rate of 21 ± 1 mm/yr (1 standard error ) in the vicinity of southern Dominican Republic, a factor of 2 higher than the NUVEL-1A plate motion model prediction of 11 ± 3 mm/yr. Independent measurements on San Andres Island, and an Euler vector derived from these data, also suggest a rate that is much higher than …

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Small Angle Neutron Scattering From Nanodroplet Aerosols, Barbara Ellen Wyslouzil, Janice L. Cheung, Gerald Wilemski, Reinhard Strey Jul 1997

Small Angle Neutron Scattering From Nanodroplet Aerosols, Barbara Ellen Wyslouzil, Janice L. Cheung, Gerald Wilemski, Reinhard Strey

Physics Faculty Research & Creative Works

We report the first measurements of small angle neutron scattering from an aerosol. The aerosol was produced by expanding a D2O-N2 vapor mixture in a supersonic Laval nozzle. The neutron wavelength (0.5 nm) is less than the typical particle size, and we can therefore derive the average particle size (5-8 nm), number density (~1012 cm-3), and polydispersity of the size distribution directly from the experimental data rather than by inferring them from complex models of particle formation and growth. We also predict and observe a Doppler shift-induced anisotropy in the scattering pattern due to …

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Canadian Cooperative Wildlife Health Centre, Volume 4-3, Summer 1997 Jul 1997

Canadian Cooperative Wildlife Health Centre, Volume 4-3, Summer 1997

Canadian Cooperative Wildlife Health Centre: Newsletters and Publications

CCWHC Newsletter on the World Wide Web
Five-Year Review of the CCWHC
Centre for Coastal Health moves to Nanaimo
Newcastle Disease in Cormorants, California, USA - May 1997
Chronic Wasting Disease of Wild Deer
Salmonellosis in Herons, Gannet
Probable Newcastle Disease in a Cormorant
Neoplasm in Eiders
Birthing Death in a Harbour Porpoise
Low Prevalence of Neoplasia in St. Lawrence River Eels
Mortality at a Bird Feeder
Strychnine Poisoning of a Peregrine Falcon
Suspected Teflon Toxicosis in Songbirds
Suspected Avitrol Poisoning of Non-target Species
Forensic (Medico-legal) Examinations
Mortality of Porpoises in British Columbia
Predator Attacks in British Columbia
Spring Botulism

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The Detoxification Of Petroleum Contaminated Coastal Plain Sandy Soil Using An Amended Vermicomposting Approach, John Charles Kraemer Jul 1997

The Detoxification Of Petroleum Contaminated Coastal Plain Sandy Soil Using An Amended Vermicomposting Approach, John Charles Kraemer

Health Services Research Dissertations

This study explores the feasibility of utilizing an amended vermicomposting treatment approach for detoxifying petroleum hydrocarbon contaminated sandy soil. The bench-scale testing of gasoline and diesel contaminated soil using three test soil vessels and one control soil vessel was performed in a laboratory setting for a six week time period. The control soil received no treatment other than distilled water to maintain soil moisture. Treatment 1 consisted of direct application of liquid municipal biologic sludge on a weekly basis. Treatment 2 consisted of the addition of 30 Eisenia foetida earthworms and distilled water. Treatment 3 consisted of direct application of …

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Researchers Pool Knowledge About Antarctic Dry Valleys, Andrew G. Fountain, Sarah Spaulding Jul 1997

Researchers Pool Knowledge About Antarctic Dry Valleys, Andrew G. Fountain, Sarah Spaulding

Geology Faculty Publications and Presentations

Most of us think of ice when we think of the Antarctic, and rightly so, considering that only 5% of it is ice-free. Dry valleys--the ice-free areas--have sandy, rocky valley floors, ice-covered lakes, and streams that flow only two months of the year. The McMurdo Dry Valleys (78øS 163øE) are the largest of these regions.

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Center For Sustainable Agricultural Systems Newsletter, July/August 1997 Jul 1997

Center For Sustainable Agricultural Systems Newsletter, July/August 1997

Center for Sustainable Agricultural Systems: Newsletters (1993-2000)

Contents:

Economic, Environmental and Sociological Effects of Whole-farm Production Systems in Eastern Nebraska: Alternative Production Systems and Quality of Life

SARE Announces Two Grant Opportunities

A Woman's Place on the Farm

Nebraska Resources Ideal for Aquaculture

Glickman Announces National Commission on Small Farms

Diverse Strategies for Diverse Crops

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