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2002

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Two Algorithms For Shaped-Based Porosity Measures, Leen-Kiat Soh Jan 2002

Two Algorithms For Shaped-Based Porosity Measures, Leen-Kiat Soh

School of Computing: Technical Reports

In this paper, we present two algorithms for shape-based porosity measures. Specifically, we describe two innovative attributes called perimeter porosity and area porosity as feature descriptors. Perimeter porosity refers to how “porous” or “weak” an image object is, while area porosity determines the degree of “branchiness” of an object. We show the applicability of the two measures through a SAR sea ice image classification example.


Dynamic Routing In Translucent Wdm Optical Networks, Xi Yang, Byrav Ramamurthy Jan 2002

Dynamic Routing In Translucent Wdm Optical Networks, Xi Yang, Byrav Ramamurthy

School of Computing: Conference and Workshop Papers

Translucent WDM optical networks use sparse placement of regenerators to overcome the impairments and wavelength contention introduced by fully transparent networks, and achieve a performance close to fully opaque networks with much less cost. Our previous study proved the feasibility of translucent networks using sparse regeneration technique. We addressed the placement of regenerators based on static schemes allowing only fixed number of regenerators at fixed locations. This paper furthers the study by proposing a suite of dynamical routing schemes. Dynamic allocation, advertisement and discovery of regeneration resources are proposed to support sharing transmitters and receivers between regeneration and access functions. …


A Set Of New Sea Ice Feature Descriptors For Sar Images, Leen-Kiat Soh Jan 2002

A Set Of New Sea Ice Feature Descriptors For Sar Images, Leen-Kiat Soh

School of Computing: Technical Reports

In this paper, we present a set of algorithms for describing sea ice features in SAR images. These algorithms we have implemented and incorporated in the ARKTOS software package, an intelligent sea ice classification. These algorithms have unique characteristics. Some are extensions or adaptations of existing image processing techniques to the specific problem domain of satellite sea ice classification, while some are innovative designs, inspired by the aforementioned problem domain. These feature descriptors may be generalized to other remote sensing applications.


Dynamic Traffic Grooming Algorithms For Reconfigurable Sonet Over Wdm Networks, Shu Zhang, Byrav Ramamurthy Jan 2002

Dynamic Traffic Grooming Algorithms For Reconfigurable Sonet Over Wdm Networks, Shu Zhang, Byrav Ramamurthy

School of Computing: Conference and Workshop Papers

The emergence of Wavelength Division Multiplexing (WDM) technology provides the capability for increasing the bandwidth of Synchronous Optical Network (SONET) rings by grooming low-speed traffic streams onto different high-speed wavelength channels. Since the cost of SONET add-drop multiplexers (SADM) at each node dominates the total cost of these networks, how to assign the wavelength, groom in the traffic and bypass the traffic through the intermediate nodes has received a lot of attention from researchers recently.


Constraint Modeling And Reformulation In The Context Of Academic Task Assignment, Robert Glaubius, Berthe Y. Choueiry Jan 2002

Constraint Modeling And Reformulation In The Context Of Academic Task Assignment, Robert Glaubius, Berthe Y. Choueiry

School of Computing: Conference and Workshop Papers

We discuss the modeling and reformulation of a resource allocation problem, the assignment of graduate teaching assistants (GTAs) to courses. Our research contributes the following:

• Formulation of the GTA assignment problem as a nonbinary CSP.

• Design of a new convention for consistency checking to deal with over-constrained problem.

• Definition of a new network-decomposable nonbinary confinement constraint.

• Evaluation of the reformulation of confinement and equality constraints on 3 real-world data sets.


Constraint Modeling And Reformulation In The Context Of Academic Task Assignment, Robert Glaubius, Berthe Y. Choueiry Jan 2002

Constraint Modeling And Reformulation In The Context Of Academic Task Assignment, Robert Glaubius, Berthe Y. Choueiry

School of Computing: Conference and Workshop Papers

We discuss the modeling and reformulation of a resource allocation problem, the assignment of Graduate Teaching Assistants to courses in the University of Nebraska-Lincoln Computer Science Department. We formulate this problem as a non-binary Constraint Satisfaction Problem (CSP) and provide a new convention for consistency checking to deal with the over-constraindness of the problem and the practical requirement of our application. We introduce a new decomposable non-binary constraint, which we call confinement constraint, and describe its relevance in practical requirements of our application. We introduce an new decomposable non-binary constraint, which we call confinement constraint, and describe its relevance in …


Arctic Ocean Snow Melt Onset Dates Derived From Passive Microwave, A New Data Set, Mark R. Anderson, Sheldon D. Drobot Jan 2002

Arctic Ocean Snow Melt Onset Dates Derived From Passive Microwave, A New Data Set, Mark R. Anderson, Sheldon D. Drobot

Department of Earth and Atmospheric Sciences: Faculty Publications

Snow melt onset is defined as the point in time when the appearance of liquid water in the snow pack changes the crystalline structure within the pack. Owing to the associated increase in surface albedo during melt, surface energy absorption increases rapidly after the onset of snow melt. Monitoring interannual variations in snow melt onset is therefore useful for accurately modeling surface conditions, and it is also valuable for validating climate models and detecting climate change. Since microwave emission changes rapidly when liquid water appears in the snow pack, passive microwave remote sensing techniques can monitor melt onset. Passive microwave …


Concordant Paleolatitudes For Neoproterozoic Ophiolitic Rocks Of The Trinity Complex, Klamath Mountains, California, Edward A. Mankinen, Nancy Lindsley-Griffin, John R. Griffin Jan 2002

Concordant Paleolatitudes For Neoproterozoic Ophiolitic Rocks Of The Trinity Complex, Klamath Mountains, California, Edward A. Mankinen, Nancy Lindsley-Griffin, John R. Griffin

Department of Earth and Atmospheric Sciences: Faculty Publications

New paleomagnetic results from the eastern Klamath Mountains of northern California show that Neoproterozoic rocks of the Trinity ophiolitic complex and overlying Middle Devonian volcanic rocks are latitudinally concordant with cratonal North America. Combining paleomagnetic data with regional geologic and faunal evidence suggests that the Trinity Complex and related terranes of the eastern Klamath plate were linked in some fashion to the North American craton throughout that time, but that distance between them may have varied considerably. A possible model that is consistent with our paleomagnetic results and the geologic evidence is that the Trinity Complex formed and migrated parallel …


New Amphicyonid Carnivorans (Mammalia, Daphoeninae) From The Early Miocene Of Southeastern Wyoming, Robert M. Hunt Jr. Jan 2002

New Amphicyonid Carnivorans (Mammalia, Daphoeninae) From The Early Miocene Of Southeastern Wyoming, Robert M. Hunt Jr.

Department of Earth and Atmospheric Sciences: Faculty Publications

Latest Arikareean sediments of the upper Arikaree Group in southeastern Wyoming produced rare fossils of large, early Miocene amphicyonid carnivorans for field parties of the Frick Laboratory, American Museum, from 1932 to 1940. Recent geologic field investigations, including mapping, have discovered additional remains of these carnivorans, clarifying their geographic and stratigraphic distribution, and permitting a more informed description of the earlier collections. These carnivorans come from tuffaceous sandstones of the Upper Harrison beds, the terminal formation-rank unit of the Arikaree Group in southeastern Wyoming. A large species of the amphicyonid Daphoenodon (D. falkenbachi, n. sp.) occurs in northern …


Intercontinental Migration Of Neogene Amphicyonids (Mammalia, Carnivora): Appearance Of The Eurasian Beardog Ysengrinia In North America, Robert M. Hunt Jr. Jan 2002

Intercontinental Migration Of Neogene Amphicyonids (Mammalia, Carnivora): Appearance Of The Eurasian Beardog Ysengrinia In North America, Robert M. Hunt Jr.

Department of Earth and Atmospheric Sciences: Faculty Publications

At the beginning of the Neogene a remarkable faunal turnover occurred within the North American carnivore community. The dominant larger Oligocene carnivores (creodonts, nimravid cats, the amphicyonid Daphoenus) became extinct during the late Oligocene and were replaced in the early Miocene by amphicyonine amphicyonids and hemicyonine ursids that entered North America from Eurasia. During a five million-year interval from ~23 to 18 Ma, large amphicyonines appear in late Arikareean and early Hemingfordian faunas of the North American midcontinent. Although most fossils are from western Nebraska and southeastern Wyoming, occurrences of amphicyonines at several sites in the eastern United States …


Field Trip Guide (For The Nebraska Well Drillers Association) Southwestern Nebraska Geology, D. Eversoll Jan 2002

Field Trip Guide (For The Nebraska Well Drillers Association) Southwestern Nebraska Geology, D. Eversoll

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Scotts Bluff County Test Hole Logs, Vincent H. Dreeszen, Steven S. Sibray, Frank A. Smith Jan 2002

Scotts Bluff County Test Hole Logs, Vincent H. Dreeszen, Steven S. Sibray, Frank A. Smith

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


A Novel Method To Improve The Test Efficiency Of Vlsi Tests, Hailong Cui, Sharad C. Seth, Shashank K. Mehta Jan 2002

A Novel Method To Improve The Test Efficiency Of Vlsi Tests, Hailong Cui, Sharad C. Seth, Shashank K. Mehta

School of Computing: Conference and Workshop Papers

This paper considers reducing the cost of test application by permuting test vectors to improve their defect coverage. Algorithms for test reordering are developed with the goal of minimizing the test cost. Best and worst case bounds are established for the performance of a reordered sequence compared to the original sequence of test application. SEMATECH test data and simulation results are used throughout to illustrate the ideas.


The Importance Of Replication In Wildlife Research, Douglas H. Johnson Jan 2002

The Importance Of Replication In Wildlife Research, Douglas H. Johnson

United States Geological Survey, Northern Prairie Wildlife Research Center: Publications

Wildlife ecology and management studies have been widely criticized for deficiencies in design or analysis. Manipulative experiments-with controls, randomization, and replication in space and time-provide powerful ways of learning about natural systems and establishing causal relationships, but such studies are rare in our field. Observational studies and sample surveys are more common; they also require appropriate design and analysis. More important than the design and analysis of individual studies is metareplication: replication of entire studies. Similar conclusions obtained from studies of the same phenomenon conducted under widely differing conditions will give us greater confidence in the generality of those findings …


Diet Of Shovelnose Sturgeon Downstream From Gavins Point Dam: Final Report, Charles R. Berry Jr. Jan 2002

Diet Of Shovelnose Sturgeon Downstream From Gavins Point Dam: Final Report, Charles R. Berry Jr.

United States Army Corps of Engineers, Omaha District

The diet of shovelnose sturgeon (Scaphirhynchus platorhynchus) in the Missouri River downstream from Gavins Point Dam was characterized in 1993 (N=100 fish) and 1994 (N=103 fish) for comparison with similar data collected in 1971-72 (N=130 fish) by Modde and Schmulbach (1977, hereafter Modde). The primary difference among years in the South Dakota studies was river discharge, which was low in 1993 (9-22 kcfs; kcfs=thousand cubic feet per second), moderate in 1994 (18-31 kcfs), and high in 1971-72 (26-49 kcfs). We compared sturgeon diet weight and the weight of benthic and drifting invertebrates among years, among monthly discharges in …


A Procedural Evaluation Of An Analytic-Deliberative Process: The Columbia River Comprehensive Impact Assessment, Aimee Guglielmo Kinney, Thomas M. Leschine Jan 2002

A Procedural Evaluation Of An Analytic-Deliberative Process: The Columbia River Comprehensive Impact Assessment, Aimee Guglielmo Kinney, Thomas M. Leschine

United States Army Corps of Engineers, Omaha District

The U.S. Department of Energy's Columbia River Comprehensive Impact Assessment (CRCIA) was an ambitious attempt to direct its cleanup of the Hanford Nuclear Reservation toward the most significant risks to the Columbia River resulting from past plutonium production. DOE's approach was uncommonly open, including tribal, regulatory agency, and other Hanford interest group representatives on the board that was to develop the assessment approach. The CRCIA process had attributes of the ``analytic-deliberative'' process for risk assessment recommended by the National Research Council. Nevertheless, differences between the DOE and other participants over what was meant by the term ``comprehensive'' in the group's …


Unifying Lectures, Recitations & Laboratories As A Part Of The Humanized Physics Project, Vicki L. Plano Clark, Robert G. Fuller Jan 2002

Unifying Lectures, Recitations & Laboratories As A Part Of The Humanized Physics Project, Vicki L. Plano Clark, Robert G. Fuller

Robert G. Fuller Publications

As a part of our work in the Humanized Physics Project, we have made the content of the physics laboratories the keystone of our physics content coverage. After having selected an appropriate human application of physics for the laboratory each week, we have shaped the lecture, recitation and homework assignments to support the laboratory. Our poster will provide examples from both semesters of our general physics course.


Segregation Of Spermatozoa Within Sperm Storage Tubules Of Fowl And Turkey Hens, L. M. King, J. P. Brillard, M. R. Bakst, A. M. Donoghue Jan 2002

Segregation Of Spermatozoa Within Sperm Storage Tubules Of Fowl And Turkey Hens, L. M. King, J. P. Brillard, M. R. Bakst, A. M. Donoghue

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

In avian species, spermatozoa reside in the oviduct for prolonged periods in specialized structures known as sperm storage tubules, but little is known about the relative distribution of spermatozoa in these tubules after successive inseminations by different males. The staining efficacies of various fluorescent dyes for fowl and turkey spermatozoa were evaluated to investigate one proposed mechanism of sperm competition. Hens were then inseminated at different intervals with stained and unstained spermatozoa to observe the spatial distribution of spermatozoa within the storage tubules. Several novel fluorescent lipophilic tracers that successfully stain mammalian spermatozoa either did not stain fowl or turkey …


Probability Of Nitrate Contamination Of Recently Recharged Groundwaters In The Conterminous United States, Bernard Nolan, Kerie Hitt, Barbara Ruddy Jan 2002

Probability Of Nitrate Contamination Of Recently Recharged Groundwaters In The Conterminous United States, Bernard Nolan, Kerie Hitt, Barbara Ruddy

United States Geological Survey: Staff Publications

A new logistic regression (LR) model was used to predict the probability of nitrate contamination exceeding 4 mg/L in predominantly shallow, recently recharged groundwaters of the United States. The new model contains variables representing (1) N fertilizer loading (p < 0.001), (2) percent cropland-pasture (p < 0.001), (3) natural log of human population density (p < 0.001), (4) percent well-drained soils (p < 0.001), (5) depth to the seasonally high water table (p < 0.001), and (6) presence or absence of unconsolidated sand and gravel aquifers (p =0.002). Observed and average predicted probabilities associated with deciles of risk are well correlated (r2 = 0.875), indicating that the LR model fits the data well. The likelihood of nitrate contamination is greater in areas with high N loading and well-drained surficial soils over unconsolidated sand and gravels. The LR model correctly predicted the status of nitrate contamination in 75% of wells in a validation data set. Considering all wells used in both calibration and …


Review Of Determination Of Organic Compounds In Soils, Sediments And Sludges By T. R. Crompton, John J. Johnston Jan 2002

Review Of Determination Of Organic Compounds In Soils, Sediments And Sludges By T. R. Crompton, John J. Johnston

United States Department of Agriculture Wildlife Services: Staff Publications

T. R. Crompton has accomplished the Herculean task of summarizing the literature (up to 1998) for the determination of organic and organometallic substances in soils, aquatic, and marine sediments and sludge. Although previous books address the analysis of such compounds in water, this is the first book dedicated to the analysis of pollutants in soils, sediments, and sludges, matrices that typically contain a variety of interfering compounds and offer significant analytical challenges. Overall, the book is relatively easy to read; the “camera ready” manuscript produced by the author contains clear tables, figures, and font. Classes of compounds addressed in this …


Safety Of Brucella Abortus Strain Rb51 Vaccine In Non-Target Ungulates And Coyotes, Terry J. Kreeger, Thomas J. Deliberto, Steven C. Olsen, William H. Edwards, Walter E. Cook Jan 2002

Safety Of Brucella Abortus Strain Rb51 Vaccine In Non-Target Ungulates And Coyotes, Terry J. Kreeger, Thomas J. Deliberto, Steven C. Olsen, William H. Edwards, Walter E. Cook

United States Department of Agriculture Wildlife Services: Staff Publications

Brucellosis is endemic in free-ranging elk (Cervus elaphus) and bison (Bison bison) in the Greater Yellowstone Area (GYA; USA). It is possible that an oral brucellosis vaccine could be developed and disseminated in the GYA to reduce disease transmission. Should this occur, non-target species other than elk and bison may come in contact with the vaccine resulting in morbidity or mortality. To assess biosafety, bighorn sheep (Ovis canadensis; n=10), pronghorn (Antilocapra americana; n=9), mule deer (Odocoileus hemionus; n=11), moose (Alces alces shirasi; n=10), and …


Overview Of Hydrocarbon Production, Consumption, Reserves And Potential, At World And Local Scales, Mitchell E. Henry, Debra Higley Jan 2002

Overview Of Hydrocarbon Production, Consumption, Reserves And Potential, At World And Local Scales, Mitchell E. Henry, Debra Higley

United States Geological Survey: Staff Publications

Hydrocarbon (oil and gas) production and consumption, along with remaining resources, are irregularly distributed across the world and within countries. Daily world hydrocarbon production, in 1999, was 72.6 million barrels of oil (mbo) and 232 billion cubic feet of gas (bcfg). Daily average production in 1999, for North America, was 14 mbo and 71.7 bcfg, and, for the United States, it was 8.1 mbo and 50.9 bcfg. North American average daily consumption for 1999 was 23.4 mbo and 71.5 bcfg. The United States produced 42 percent of the oil and 85 percent of the gas it consumed in 1999. Onshore …


Wildlife Diseases: Crying Wolf Or Crying Shame?, Robert G. Mclean Jan 2002

Wildlife Diseases: Crying Wolf Or Crying Shame?, Robert G. Mclean

United States Geological Survey: Staff Publications

Diseases of North American wildlife are causing serious problems for wildlife, and some wildlife diseases pose health threats to humans and domestic animals. Information will be presented at this wildlife disease session to alert resource managers enough to consider disease as an important issue when managing wildlife populations. It will be a crying shame if appropriate actions are not taken to monitor diseases adequately and to prevent or control them to protect our wildlife resources.


The Last Interglacial Period On The Pacific Coast Of North America: Timing And Paleoclimate, Daniel R. Muhs, Kathleen R. Simmons, George L. Kennedy, Thomas K. Rockwell Jan 2002

The Last Interglacial Period On The Pacific Coast Of North America: Timing And Paleoclimate, Daniel R. Muhs, Kathleen R. Simmons, George L. Kennedy, Thomas K. Rockwell

United States Geological Survey: Staff Publications

New, high-precision U-series ages of solitary corals (Balanophyllia elegans) coupled with molluscan faunal data from marine terraces on the Pacific Coast of North America yield information about the timing and warmth of the last interglacial sea-level highstand. Balanophyllia elegans takes up U in isotopic equilibrium with seawater during growth and shortly after death. Corals from the second terrace on San Clemente Island (offshore southern California), the third terrace on Punta Banda (on the Pacific Coast of northern Baja California), and the Discovery Point Formation on Isla de Guadalupe (in the Pacific Ocean offshore Baja California) date to the …


Evidence For The Timing And Duration Of The Last Interglacial Period From High-Precision Uranium-Series Ages Of Corals On Tectonically Stable Coastlines, Daniel R. Muhs Jan 2002

Evidence For The Timing And Duration Of The Last Interglacial Period From High-Precision Uranium-Series Ages Of Corals On Tectonically Stable Coastlines, Daniel R. Muhs

United States Geological Survey: Staff Publications

The last interglacial period has a timing and duration that can be estimated from U-series dating of emergent, coral-bearing deposits on tectonically stable coastlines. High-precision dating from Bermuda, the Bahamas, Hawaii, and Australia suggests that the last interglacial period had a sea level at least as high as present from ~128,000 to 116,000 yr B.P. Sea level reached a near-present level more quickly after the close of the penultimate glacial period than at the close of the last glacial period and the duration of high sea level is longer than that implied by the deep-sea record.


A Comparative Study Of Geometric Rule Learning By Nutcrackers (Nucifraga Columbiana), Pigeons (Columba Livia), And Jackdaws (Corvus Monedula ), Juli E. Jones, Elena Antoniadis, Sara J. Shettleworth, Alan Kamil Jan 2002

A Comparative Study Of Geometric Rule Learning By Nutcrackers (Nucifraga Columbiana), Pigeons (Columba Livia), And Jackdaws (Corvus Monedula ), Juli E. Jones, Elena Antoniadis, Sara J. Shettleworth, Alan Kamil

Papers in Behavior in Biological Sciences

Three avian species, a seed-caching corvid (Clark’s nutcrackers; Nucifraga columbiana), a non-seed-caching corvid (jackdaws; Corvus monedula), and a non-seed-caching columbid (pigeons; Columba livia), were tested for ability to learn to find a goal halfway between 2 landmarks when distance between the landmarks varied during training. All 3 species learned, but jackdaws took much longer than either pigeons or nutcrackers. The nutcrackers searched more accurately than either pigeons or jackdaws. Both nutcrackers and pigeons showed good transfer to novel landmark arrays in which interlandmark distances were novel, but inconclusive results were obtained from jackdaws. Species differences in this …


Holographic Recording Of Fast Events On A Ccd Camera, Zhiwen Liu, Martin Centurion, George Panotopoulos, John Hong, Demetri Psaltis Jan 2002

Holographic Recording Of Fast Events On A Ccd Camera, Zhiwen Liu, Martin Centurion, George Panotopoulos, John Hong, Demetri Psaltis

Martin Centurion Publications

We report on holographic recording of nanosecond events on a conventional CCD camera. Three frames of an air-discharge event, with resolution of 5.9 ns and frame interval of 12 ns, are recorded in a single CCD frame. Each individual frame is reconstructed by digital filtering of the CCD frame, since successively recorded holograms are centered at different carrier frequencies in the spatial frequency domain.


Neutron Powder Diffraction Studies Of The La0.65Pb0.35Mno3 Perovskite, Camelia Borca, Shireen Adenwalla, Sy-Hwang Liou, Q.L. Xu, J. L. Robertson, Peter A. Dowben Jan 2002

Neutron Powder Diffraction Studies Of The La0.65Pb0.35Mno3 Perovskite, Camelia Borca, Shireen Adenwalla, Sy-Hwang Liou, Q.L. Xu, J. L. Robertson, Peter A. Dowben

Peter Dowben Publications

The structure of La0.65Pb0.35MnO3 has been studied by neutron powder diffraction. From the temperature dependence of the lattice parameters, we observe that La0.65Pb0.35MnO3 remains single phase in the temperature interval from 25 to 400 K, with a rhombohedral (R3c) structure. The collinear Mn spins suffer a thermally driven reorientation transition close to the Curie temperature, as obtained from powder samples (using neutron diffraction) and from thin films [using ferromagnetic resonance (FMR)]. The reorientation transition may indicate the presence of local Jahn–Teller (JT) lattice distortions, which are prevented from …


How Does Water Freeze Inside Carbon Nanotubes?, Kenichiro Koga, G.T. Gao, Hideki Tanaka, Xiao Cheng Zeng Jan 2002

How Does Water Freeze Inside Carbon Nanotubes?, Kenichiro Koga, G.T. Gao, Hideki Tanaka, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Phase behavior of quasi-one-dimensional water confined inside a carbon nanotube is studied in the thermodynamic space of temperature, pressure, and diameter of the cylindrical container. Four kinds of solid-like ordered structures—ice nanotubes—form spontaneously from liquid-like disordered phases at low temperatures. In the model system that comprises of TIP4P water molecules interacting with each other via short-range Lennard–Jones and long-range Coulomb site–site potentials under a periodic boundary condition in the axial direction, the phase change occurs either discontinuously or continuously depending on the path in the thermodynamic space. That the isotherms for a given diameter are found to be similar to …


Implications Of Single-Particle Experiments For Track Theory, Therapy And Radiation Protection, Robert Katz, Francis Cucinotta Jan 2002

Implications Of Single-Particle Experiments For Track Theory, Therapy And Radiation Protection, Robert Katz, Francis Cucinotta

Robert Katz Publications

‘‘Because the predominant exposure of cells in humans is to single isolated tracks, a critical question is what effects a single track is capable of producing and with what probabilities.’’ ‘‘Most of the current biophysical models. . . make the clear prediction that a single track can produce virtually all of the detrimental stochastic effects of interest.’’ ‘‘But one model, in particular (the amorphous track model of Katz and coworkers), disagrees fundamentally that a single low LET track has the ability to cause the cellular changes.’’ ‘‘This model leads to very dramatic differences in the predicted risk at low doses. …