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

Physical Sciences and Mathematics Commons

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

2001

Utah State University

Discipline
Keyword
Publication
Publication Type
File Type

Articles 1 - 30 of 67

Full-Text Articles in Physical Sciences and Mathematics

Metaxpath, Curtis Dyreson, Michael H. Böhen, Christian S. Jensen Dec 2001

Metaxpath, Curtis Dyreson, Michael H. Böhen, Christian S. Jensen

Curtis Dyreson

This paper presents the METAXPath data model and query language. METAXPath extends XPath with support for XML metadata. XPath is a specification language for locations in an XML document it serves as the basis for XML query languages like XSLT and the XML Query Algebra.

The METAXPath data model is a nested XPath tree. Each level of metadata induces a new level of nesting. The data model separates metadata and data into different data spaces, supports meta-metadata and enables sharing of metadata common to a group of nodes without duplication. The METAXPath query language has a level shift operator to …


Risk Mapping For Northern Kenya And Southern Ethiopia, D. Layne Coppock Dec 2001

Risk Mapping For Northern Kenya And Southern Ethiopia, D. Layne Coppock

Environment and Society Faculty Publications

We used results from 120 group interviews collected in 1998 to quantify how inhabitants across northern Kenya and southern Ethiopia perceive and rank various risks to their livelihoods. We also mapped risk patterns using Global Positioning System (GPS) coordinates. Respondents recognized 15 sources of risk overall, with the most common being reliable access to food and water. Other risks were not mentioned by a majority of respondents and reflected diversity in local situations. Country of residence, wealth class, gender, and predominant means of food production (pastoralism, agro-pastoralism, and farming) influenced risk ranking. For example, wealthy males were most concerned about …


Effects Of A Large Mesospheric Temperature Enhancement On The Hydroxyl Rotational Temperature As Observedfrom The Ground, S. M.L. Melo, R. P. Lowe, W. R. Pendleton Jr., Michael J. Taylor, B. Williams, C. Y. She Dec 2001

Effects Of A Large Mesospheric Temperature Enhancement On The Hydroxyl Rotational Temperature As Observedfrom The Ground, S. M.L. Melo, R. P. Lowe, W. R. Pendleton Jr., Michael J. Taylor, B. Williams, C. Y. She

All Physics Faculty Publications

The rotational temperature obtained from the rotational population distribution in the bands of the hydroxyl airglow has been shown to be a suitable proxy for the temperature at a height of 87 km [She and Lowe, 1998]. In this paper we examine in detail simultaneous observations on November 2–3, 1997, at Fort Collins, Colorado (41°N, 105°W), with both a sodium temperature lidar and the Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) OH mesospheric temperature mapper during which significant differences between the hydroxyl and lidar temperatures occur. The large differences are associated with a major temperature enhancement in the region …


Climatology Of Mid- And Low-Latitude F Region Disturbance Winds Measured By Windii, J. T. Emmert, Bela G. Fejer, C. G. Fesen, G. G. Shepherd, B. H. Solheim Nov 2001

Climatology Of Mid- And Low-Latitude F Region Disturbance Winds Measured By Windii, J. T. Emmert, Bela G. Fejer, C. G. Fesen, G. G. Shepherd, B. H. Solheim

Bela G. Fejer

No abstract provided.


Interpreting Fracture Patterns In Sandstones Interbedded With Ductile Strata At The Salt Valley Anticline, Arches National Park, Utah, John C. Lorenz, Scott P. Cooper Nov 2001

Interpreting Fracture Patterns In Sandstones Interbedded With Ductile Strata At The Salt Valley Anticline, Arches National Park, Utah, John C. Lorenz, Scott P. Cooper

All U.S. Government Documents (Utah Regional Depository)

Sandstones that overlie or that are interbedded with evaporitic or other ductile strata commonly contain numerous localized domains of fractures, each covering an area of a few square miles. Fractures within the Entrada Sandstone at the Salt Valley Anticline are associated with salt mobility within the underlying Paradox Formation. The fracture relationships observed at Salt Valley (along with examples from Paleozoic strata at the southern edge of the Holbrook basin in northeastern Arizona, and sandstones of the Frontier Formation along the western edge of the Green River basin in southwestern Wyoming), show that although each fracture domain may contain consistently …


An Unusual Airglow Waveevent Observed At Cachoeira Paulista 23°S, A. F. Medeiros, Michael J. Taylor, H. Takahashi, P. P. Batista, D. Gobbi Oct 2001

An Unusual Airglow Waveevent Observed At Cachoeira Paulista 23°S, A. F. Medeiros, Michael J. Taylor, H. Takahashi, P. P. Batista, D. Gobbi

All Physics Faculty Publications

An all-sky CCD airglow imager has been used to obtain a wealth of data on the MLT airglow emissions from Cachoeira Paulista, Brazil (22.7° S, 45.0° W). Measurements of the NIR OH, OI(557.7 nm), O2(0,1) and the thermospheric OI(630.0 nm) emissions have been made since October 1998. In addition, simultaneous measurements of the airglow zenith intensities and rotational temperatures, and vertical wind structure between 80 and 100 km were made using a co-located multi-channel photometer and a meteor radar. On the night of July 13, 1999, the CCD images showed active wave events exhibiting a variety of short period wave …


Multiplewavelength Optical Observations Of A Long-Lived Meteor Trail, B. R. Clemesha, A. F. Medeiros, D. Gobbi, H. Takahashi, P. P. Batista, Michael J. Taylor Jul 2001

Multiplewavelength Optical Observations Of A Long-Lived Meteor Trail, B. R. Clemesha, A. F. Medeiros, D. Gobbi, H. Takahashi, P. P. Batista, Michael J. Taylor

All Physics Faculty Publications

A long‐lived meteor trail has been observed at wavelengths of 572.5 nm, 557.7 nm, 630.0 nm, 865.5 nm and in the near infrared band from 715 to 930 nm. The trail was detected at all these wavelengths, with the possible exception of 865.5 nm, where its identification was marginal. It was seen longest (17 minutes) through the wide band NIR 715‐930 nm filter. The fact that the trail was only marginally visible in the 865.5 nm (0–1) band of molecular oxygen, and was strongest in the wide‐band NIR image, raises serious doubts about an earlier suggestion that the infrared light …


Low-Flow Test, San Juan River, Final Environmental Assessment, United States Department Of Interior, Bureau Of Reclamation Jun 2001

Low-Flow Test, San Juan River, Final Environmental Assessment, United States Department Of Interior, Bureau Of Reclamation

All U.S. Government Documents (Utah Regional Depository)

This final environmental assessment (EA) is prepared in compliance with the National Environmental Policy Act (NEPA) of 1969 (Public Law 91-190) to evaluate test flows from Navajo Dam into the San Juan River.

The underlying need for this proposed test is to evaluate the effect of low summer flows on various resources. The information obtained will be used in preparation of an environmental impact statement (EIS) on operating Navajo Reservoir to mimic a natural hydrograph in critical habitat of the San Juan River for the benefit of downstream endangered fish and to allow for future water development.


A Natural Channel Design To Restore The Greenwater River, Washington, Gregory J. Laurie May 2001

A Natural Channel Design To Restore The Greenwater River, Washington, Gregory J. Laurie

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Channelization of the Greenwater River has resulted in a loss of habitat for Chinook salmon, a species listed as threatened under the Endangered Species Act. In order to restore habitat for fish and other aquatic organisms, a design was developed to restore meanders to the original floodplain. The channel design process began at the watershed scale, and progressed down to the scale of the stream channel. A twelve-step design process was followed that considered the influence of watershed disturbances on channel forming processes. Trends in sediment yield were assessed using an existing landslide inventory, and changes in channel pattern were …


Detection Of Changes In Financial Time Series, Rich Madsen May 2001

Detection Of Changes In Financial Time Series, Rich Madsen

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

The purpose of this paper is to examine and model data from several years of foreign currency trading, to determine if one or more change points has occured in the data, and to estimate when those change points took place. Leading up to the analysis of the data we will construct and develop several statistics which we will use to determine if a change point has occured.

This paper falls into the area of computational statistics and will make use of Splus and the S+GARCH module within Splus. Heavy use will also be made of C++. The models that we …


Generalized Minimum Penalized Hellinger Distance Estimation And Generalized Penalized Hellinger Deviance Testing For Generalized Linear Models: The Discrete Case, Huey Yan May 2001

Generalized Minimum Penalized Hellinger Distance Estimation And Generalized Penalized Hellinger Deviance Testing For Generalized Linear Models: The Discrete Case, Huey Yan

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In this dissertation, robust and efficient alternatives to quasi-likelihood estimation and likelihood ratio tests are developed for discrete generalized linear models. The estimation method considered is a penalized minimum Hellinger distance procedure that generalizes a procedure developed by Harris and Basu for estimating parameters of a single discrete probability distribution from a random sample. A bootstrap algorithm is proposed to select the weight of the penalty term. Simulations are carried out to compare the new estimators with quasi-likelihood estimation. The robustness of the estimation procedure is demonstrated by simulation work and by Hapel's α-influence curve. Penalized minimum Hellinger deviance tests …


Mesospheric Planetary Waves Atnorthern Hemisphere Fall Equinox, H. L. Liu, R. G. Roble, Michael J. Taylor, W. R. Pendleton Jr. May 2001

Mesospheric Planetary Waves Atnorthern Hemisphere Fall Equinox, H. L. Liu, R. G. Roble, Michael J. Taylor, W. R. Pendleton Jr.

All Physics Faculty Publications

Northern hemisphere planetary waves are strong in the winter and weak in the summer, and they go through a fast transition around equinox. This transition is studied here using NCAR Thermosphere‐Ionosphere‐Mesosphere‐Electrodynamics general circulation model (TIME‐GCM) simulations with 1997 National Centers for Environmental Prediction (NCEP) analysis. The planetary wave variability during the transition and its effect on the temperature and winds in the mesosphere are examined. The simulated planetary wave structure agrees with climatological studies, and the fast transition of the planetary waves is captured by the model. The wave variability produces large temperature changes in the upper atmosphere above local …


Large Amplitude Perturbations In Mesospheric Oh Meinel And 87-Km Na Lidar Temperatures Around The Autumnal Equinox, Michael J. Taylor, W. R. Pendleton Jr., H. L. Liu, C. Y. She, Larry Gardner, R. G. Roble, V. Vasoli May 2001

Large Amplitude Perturbations In Mesospheric Oh Meinel And 87-Km Na Lidar Temperatures Around The Autumnal Equinox, Michael J. Taylor, W. R. Pendleton Jr., H. L. Liu, C. Y. She, Larry Gardner, R. G. Roble, V. Vasoli

All Physics Faculty Publications

Two high‐precision CEDAR instruments, an OH Mesospheric Temperature Mapper (MTM) and a Na Temperature Lidar, have been used to investigate seasonal variability in the mid‐latitude temperature at ∼87 km altitude over the western USA. Here we report the observation of a large perturbation in mesospheric temperature that occurs shortly after the autumnal equinox in close association with the penetration of planetary‐wave energy from the troposphere into the mesosphere. This perturbation has been observed on three occasions and exhibits a departure of up to ∼25–30 K from the nominal seasonal trend during a disturbed period of ∼2 weeks. Such behavior represents …


Controls On Channel Organization And Morphology In A Glaciated Basin In The Uinta Mountains, Utah, Betty E. Paepke May 2001

Controls On Channel Organization And Morphology In A Glaciated Basin In The Uinta Mountains, Utah, Betty E. Paepke

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The organization and morphology of Middle Fork Sheep Creek and South Fork Sheep Creek, two mountain streams in the upper Sheep Creek basin, are controlled by the spatial distribution of glacial moraines. Both channels are organized into a reoccurring sequence of steep-gradient reaches changing downstream to low-gradient reaches. Steep-gradient reaches are located where the channels flow through moraine s. Low-gradient reaches are located in meadows downstream of the steep-gradient reaches and immediately upstream of the next moraine. Knickpoints in the longitudinal profiles of both streams coincide with the location of moraines.

Large boulder s, beyond the size transportable by the …


Climatology Of Upper Thermospheric Daytime Neutral Winds From Satellite Observations, John T. Emmert May 2001

Climatology Of Upper Thermospheric Daytime Neutral Winds From Satellite Observations, John T. Emmert

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

We studied the global climatology of mid- and low-latitude F region daytime neutral winds using extensive measurements by the Wind Imaging Interferometer (WINDII) instrument on board the Upper Atmosphere Research Satellite (UARS). Quiet-time winds are mostly poleward and westward during the day, and are generally 5-20 m/s smaller in the longitudinal sector closest to the magnetic pole, compared to longitudinally averaged winds. The pre-noon zonal winds are less westward with increasing solar flux, while the post-noon meridional winds are less poleward. Our quiet-time results are in good agreement with the NCAR Thermosphere-Ionosphere- Electrodynamics General Circulation Model (TIEGCM).

We computed residual …


Ecology Of Treeline Whitebark Pine (Pinus Albicaulis) Populations In Central Idaho: Successional Status, Recruitment, And Mortality, And A Spring Temperature Reconstruction From Whitebark Pine Tree Rings, Dana Lee Perkins May 2001

Ecology Of Treeline Whitebark Pine (Pinus Albicaulis) Populations In Central Idaho: Successional Status, Recruitment, And Mortality, And A Spring Temperature Reconstruction From Whitebark Pine Tree Rings, Dana Lee Perkins

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This research investigated the successional status of treeline whitebark pine (Pinus albicaulis) populations on 14 stands in central Idaho and used empirical statistical models to determine the principal factors affecting recruitment and mortality. The longest lived whitebark pines from four additional high-elevation sites were used to develop a tree-ring chronology to reconstruct over 1,000 years of average April-May temperature.

The assessment of stand structures using size-frequency distributions generally provides evidence that treeline whitebark pine populations are currently self-sustaining in areas of low to nonexistent incidence of white pine blister rust (Cronartium ribicola). However the presence of …


Incorporating Technology In Mathematics Education: A Suite Of E-Activities For The Modem Mathematics Classroom, Jennifer E. Youngberg May 2001

Incorporating Technology In Mathematics Education: A Suite Of E-Activities For The Modem Mathematics Classroom, Jennifer E. Youngberg

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

National studies indicate major deficiencies in students' understanding of mathematics. Research suggests that students tend to view mathematics as a set of computational rules rather than a process of discovery and a tool for problem-solving. Most students fail to grasp the concepts behind the computations.

Technology provides a partial solution to this problem. Over the past decade, computers have emerged as a powerful tool in education. Computers place the control of action in the learning process with the student. They allow students to experiment with, explore, and discover mathematics at their own pace. With computers, students can consider more examples …


The Modern Mathematics Classroom: A Collection Of Virtual Manipulatives For Teachers And Students, David Stowell May 2001

The Modern Mathematics Classroom: A Collection Of Virtual Manipulatives For Teachers And Students, David Stowell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

An important assumption in the implementation of the National Council of Teachers of Mathematics (NCTM) Standards 2000 is that the mathematics classroom is a place where students are actively involved in the learning process. One way to foster such a learning environment is by using manipulatives. By their nature, manipulatives make the learning of mathematics a discovery-based activity. As computer use increases in the classroom, virtual manipulatives will become more important as instructional tools. Virtual manipulatives offer advantages over their traditional versions. Most important is their dynamic nature. Their dynamic capabilities provide two main benefits. First, the number of potential …


Intensification In A Risky Environment: The Case Of Improving Private Grazing Land For Beef Production In Utah, Louise D. Sainsbury May 2001

Intensification In A Risky Environment: The Case Of Improving Private Grazing Land For Beef Production In Utah, Louise D. Sainsbury

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Utah ranchers commonly face risks to their livelihoods. The objective of this work was to determine if ranchers could make profitable improvements to private land forage given the combined threat of low beef prices, drought, and possible loss of public grazing.

We used linear programming (LINDO) to identify the most profitable solutions for private land investment with an 11-year simulation. Operations were divided into small, medium, and large size classes. Various forage improvements and public permits were options. Two phases of a beef price cycle (peak and trough) and 2 precipitation patterns (wet and drought) were combined as joint favorable …


Effects Of High Ammonium/Nitrate Ratios On Nitrification And Growth Of Wheat In Hydroponics, Dawn J. Muhlestein May 2001

Effects Of High Ammonium/Nitrate Ratios On Nitrification And Growth Of Wheat In Hydroponics, Dawn J. Muhlestein

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nitrogen is the only plant nutrient taken up as both a cation (NH4+) and anion (NO3-). Nitrate is considered the "safe" form of N and NH/ is generally thought to be toxic, especially at high levels. High NH4+/NO3- ratios are thought to be toxic because they result in a rhizosphere pH low enough to damage root membranes, induced cation deficiencies, and build-up of NH3 caused by delayed NH/ assimilation. These factors can be minimized in hydroponic culture. The objective of these studies was to quantify the effects of high …


Structural And Geochemical Analyses Of Disseminated-Gold Deposits, Bald Mountain-Alligator Ridge District, Nevada: Insights Into Fault-Zone Architecture And Its Effect On Mineralization, K. Jill Hammond May 2001

Structural And Geochemical Analyses Of Disseminated-Gold Deposits, Bald Mountain-Alligator Ridge District, Nevada: Insights Into Fault-Zone Architecture And Its Effect On Mineralization, K. Jill Hammond

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Structural and geochemical analyses of the Top and Casino deposits, Bald Mountain-Alligator Ridge district, Nevada, were conducted to determine how structures affected gold deposition in Carlin-type deposit s. We also examined how permeability changed over time in a fault that cuts siltstone-dominated sedimentary rocks. The association of gold and related arsenic with faults at the margins of a Jurassic pluton and sedimentary rocks suggests that ore fluids migrated along faults and fracture s. Permeability of the faults changed over time within the Casino deposit, where the ore-controlling fault was a distributed conduit in the early stages of mineralization but a …


The Efficacy Of Plant Residue Degradation Products On Phosphorus, Iron, Iodine, And Fluorine Bioavailability To Plants, Cheryl L. Mackowiak May 2001

The Efficacy Of Plant Residue Degradation Products On Phosphorus, Iron, Iodine, And Fluorine Bioavailability To Plants, Cheryl L. Mackowiak

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Plant and animal wastes degrade in soils to form relatively stable humified compounds, which form ion complexes that affect the bioavailability of elements in the soil solution. Hydroponic studies with wheat and rice were conducted to characterize the effect of humic acid (HA) on phosphorus (P), iron (Fe), fluorine (F), and iodine (I) bioavailability. Ferrihydrite [Fe(OH)3] precipitation was greater on root surfaces without HA or synthetic chelates. Oxides such as ferrihydrite strongly adsorb P and provide exchange sites for metals. HA reduced this precipitate and increased P and Fe uptake.

Humic acid had no effect on F toxicity …


Effectiveness Of Earthen Escape Ramps In Reducing Big Game Mortality In Utah, Mary L. Hammer May 2001

Effectiveness Of Earthen Escape Ramps In Reducing Big Game Mortality In Utah, Mary L. Hammer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

One-way escape gates and earthen escape ramps are structures used to enable deer to exit the highway right-of-way along fenced roads. I compared the use of one-way escape gates and earthen escape ramps by mule deer on two highways in Utah to determine if deer exhibited a preference for either structure. Results showed that earthen escape ramps were used by mule deer 8-11 times more frequently than one-way gates. Highway mortality data suggest that the installation of the escape ramps likely reduced mortality of mule deer in both study locations, because we could not attribute reductions in mortality to decreased …


Experimental Investigation Of Snapover: The Sudden Increase Of Plasma Current Drawn To A Positively Biased Conductor When Surrounded By A Dielectric, Clint D. Thomson May 2001

Experimental Investigation Of Snapover: The Sudden Increase Of Plasma Current Drawn To A Positively Biased Conductor When Surrounded By A Dielectric, Clint D. Thomson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Snapover is particularly relevant to Earth-orbiting spacecraft powered by high-voltage solar arrays. During snapover, the current collected by a positively biased conductor that is immersed in a plasma suddenly increases when two conditions are met: i) there is an immediately adjacent insulator; ii) the conductor exceeds a positive threshold voltage with respect to the plasma. The enhanced current develops as a consequence of the insulator, either through secondary electron (SE) emission or by material ionization. Experiments were performed to examine snapover onset potential and current collection dependence on conductor and insulator materials, conductor size and shape, sample history, biasing rate, …


Structural Analysis And A Kink Band Model For The Formation Of The Gemini Fault Zone, An Exhumed Left-Lateral Strike Slip Fault Zone In The Central Sierra Nevada, California, Matthew A. Pachell May 2001

Structural Analysis And A Kink Band Model For The Formation Of The Gemini Fault Zone, An Exhumed Left-Lateral Strike Slip Fault Zone In The Central Sierra Nevada, California, Matthew A. Pachell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The structure and regional tectonic setting of an exhumed, 9.3-km long, left-lateral strike-slip fault zone eludicates processes of growth, linkage, and termination for strike-slip fault zones in granitic rocks. The Gemini fault zone is composed of three steeply dipping, southwest-striking, noncoplanar segments that nucleated and grew along preexisting joints. The fault zone has a maximum slip of 131 m and is an example of a segmented, hard-linked fault zone in which geometrical complexities of the faults and compositional variations of protolith and host rock resulted in nonuniform slip orientations, complex interactions at fault segments, and an asymmetric slip-distance profile. Regional …


The Vacuum Excitation And Squeezing Properties Of Two Quantum Oscillators With Delta-Kicked Interactions, J Y. Ji, David Peak Apr 2001

The Vacuum Excitation And Squeezing Properties Of Two Quantum Oscillators With Delta-Kicked Interactions, J Y. Ji, David Peak

All Physics Faculty Publications

The vacuum excitation and squeezing of two harmonic oscillators with delta-kicked interactions for four types of elementary coupling are studied. The exact quantum motion for the Heisenberg operators and the explicit form of squeezing operators are found. The variances are calculated to study the squeezing properties for position, momentum and generalized quadrature operators.


Visitor Capacity In The National Park System, Dr. Glenn E. Haas, National Park Service, U.S. Department Of The Interior Apr 2001

Visitor Capacity In The National Park System, Dr. Glenn E. Haas, National Park Service, U.S. Department Of The Interior

All U.S. Government Documents (Utah Regional Depository)

This paper reviews social science research on visitor capacity relevant to units of the National Park System (NPS). Visitor capacity is defined as a prescribed number and type of people that an area will accommodate given the desired natural/cultural resource conditions, visitor experiences, and management program. Some 40 years of scientific investigation illustrate the complexity of the interaction between human use and park resources. This paper provides insights from environmental psychology on person-environment relationships, nine capacity-related research findings, a matrix of NPS studies, and recommendations for a program of research.


Weed Control Methods Handbook: Tools & Techniques For Use In Natural Areas, Mandy Tu, Callie Hurd, John M. Randall, The Nature Conservancy Apr 2001

Weed Control Methods Handbook: Tools & Techniques For Use In Natural Areas, Mandy Tu, Callie Hurd, John M. Randall, The Nature Conservancy

All U.S. Government Documents (Utah Regional Depository)

Invasive non-native plants are a serious threat to native species, communities, and ecosystems in many areas around the world. They can compete with and displace native plants, animals, and other organisms that depend on them, alter ecosystem functions and cycles significantly, hybridize with native species, and promote other invaders. The good news is that many plant invasions can be reversed, halted or slowed, and in certain situations, even badly infested areas can be restored to healthy systems dominated by native species. In most instances this requires taking action to control and manage those invasive plants. This handbook provides you with …


Critical Wavelength For River Meandering, Boyd F. Edwards, D. H. Smith Mar 2001

Critical Wavelength For River Meandering, Boyd F. Edwards, D. H. Smith

All Physics Faculty Publications

A fully nonlinear modal analysis identifies a critical centerline wave number qc for river meandering that separates long-wavelength bends, which grow to cutoff, from short-wavelength bends, which decay. Exact, numerical, and approximate analytical results for qc rely on the Ikeda, Parker, and Sawai [J. Fluid Mech. 112, 363 (1981)] model, supplemented by dynamical equations that govern the river migration and length. Predictions also include upvalley bend migration at long times and a peak in lateral migration rates at intermediate times. Experimental tests are suggested.


Radar Studies Of Mid-Latitude Ionospheric Plasma Drifts, L. Scherliess, Bela G. Fejer, J. Holt, L. Goncharenko, C. Armory-Mazaudier, M. J. Buonsanto Feb 2001

Radar Studies Of Mid-Latitude Ionospheric Plasma Drifts, L. Scherliess, Bela G. Fejer, J. Holt, L. Goncharenko, C. Armory-Mazaudier, M. J. Buonsanto

Bela G. Fejer

We use incoherent scatter radar measurements from Millstone Hill and Saint Santin to study the midlatitude F region electrodynamic plasma drifts during geomagnetically quiet and active periods. We present initially a local time, season, and solar flux dependent analytical model of the quiet time zonal and meridional E × B drifts over these stations. We discuss, for the first time, the Saint Santin drift patterns during solar maximum. We have used these quiet time models to extract the geomagnetic perturbation drifts which were modeled as a function of the time history of the auroral electrojet indices. Our results illustrate the …