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Articles 1 - 30 of 203

Full-Text Articles in Physical Sciences and Mathematics

Foundations Of Wave Phenomena, Charles G. Torre Dec 2016

Foundations Of Wave Phenomena, Charles G. Torre

Charles G. Torre

This is an undergraduate text on the mathematical foundations of wave phenomena. Version 8.2.

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Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, Charles G. Torre, Dionisios Krongos Jul 2015

Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, Charles G. Torre, Dionisios Krongos

Charles G. Torre

Rainich-type conditions giving a spacetime “geometrization” of matter fields in general relativity are reviewed and extended. Three types of matter are considered: perfect fluids, scalar fields, and electromagnetic fields. Necessary and sufficient conditions on a spacetime metric for it to be part of a perfect fluid solution of the Einstein equations are given. Formulas for constructing the fluid from the metric are obtained. All fluid results hold for any spacetime dimension. Geometric conditions on a metric which are necessary and sufficient for it to define a solution of the Einstein-scalar field equations and formulas for constructing the scalar field from …

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A Solution In Weyl Gravity With Planar Symmetry, James Thomas Wheeler May 2015

A Solution In Weyl Gravity With Planar Symmetry, James Thomas Wheeler

James Thomas Wheeler

We solve the Bach equation for Weyl gravity for the case of a static metric with planar symmetry. The solution is not conformal to the solution to the corresponding Einstein equation.

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The Spacetime Co-Torsion In Torsion-Free Biconformal Spaces, James Thomas Wheeler Feb 2015

The Spacetime Co-Torsion In Torsion-Free Biconformal Spaces, James Thomas Wheeler

James Thomas Wheeler

In preceding studies, [TR Gamma minus, TR Gamma plus] we showed that the solution for the connection of flat biconformal space also solves the curved space field equations for the torsion and co-torsion. We continued this investigation with an attempt to solve the full set of torsion and co-torsion field equations, with only the assumption of vanishing torsion and the known form of the metric. We successfully reduced the torsion equations to a single equation. Here, we reduce that equation to its essential degrees of freedom. We find that the spacetime co-torsion is entirely determined by the scale vector and …

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Variation Of The Weyl Action, James Thomas Wheeler Feb 2015

Variation Of The Weyl Action, James Thomas Wheeler

James Thomas Wheeler

We show how to vary the fourth order Weyl gravity action to derive the Bach equation.

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Torsion Free Biconformal Spaces: Reducing The Torsion Field Equations, James Thomas Wheeler Jan 2015

Torsion Free Biconformal Spaces: Reducing The Torsion Field Equations, James Thomas Wheeler

James Thomas Wheeler

Our goal is to solve the full set of torsion and co-torsion field equations of Euclidean biconformal space, with only the assumption of vanishing torsion. Here we begin by resolving the involution constraints, symmetry conditions and torsion field equation into a single equation for further study.

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A Systems-Based Approach To Address Unintended Consequences Of Demand-Driven Transportation Planning In National Parks And Public Lands, Steven Lawson, Peter Newman, Christopher Monz Jan 2015

A Systems-Based Approach To Address Unintended Consequences Of Demand-Driven Transportation Planning In National Parks And Public Lands, Steven Lawson, Peter Newman, Christopher Monz

Christopher Monz

No abstract provided.

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Linkages Between Water Challenges And Land Use Planning In Megacities, Enjie Li, Joanna Endter-Wada, Shujuan Li Jan 2015

Linkages Between Water Challenges And Land Use Planning In Megacities, Enjie Li, Joanna Endter-Wada, Shujuan Li

Joanna Endter-Wada

No abstract provided.

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Gauge Theories Of General Relativity, James Thomas Wheeler Nov 2014

Gauge Theories Of General Relativity, James Thomas Wheeler

James Thomas Wheeler

General relativity can be seen as a gauge theory of the Lorentz, Poincaré, Weyl, de Sitter, or conformal groups. In most of these, there is little or no difference from the standard formulation in Riemannian geometry, but the higher symmetries — de Sitter and conformal — introduce new features and explain old ones. The potential presence of a cosmological constant, the spacetime metric, cosmological dust, symplectic structure, Kähler structure and even the existence of a timelike direction can all be seen to arise from the underlying group structure.

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Weyl Gravity As General Relativity, James Thomas Wheeler Jul 2014

Weyl Gravity As General Relativity, James Thomas Wheeler

James Thomas Wheeler

When the full connection of Weyl conformal gravity is varied instead of just the metric, the resulting vacuum field equations reduce to the vacuum Einstein equation, up to the choice of local units, if and only if the torsion vanishes. This result differs strongly from the usual fourth-order formulation of Weyl gravity.

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Perihelion Precession In General Relativity, Charles G. Torre Apr 2014

Perihelion Precession In General Relativity, Charles G. Torre

Charles G. Torre

This is a Maple worksheet providing a relatively quick and informal sketch of a demonstration that general relativistic corrections to the bound Kepler orbits introduce a perihelion precession. Any decent textbook will derive this result. My analysis aligns with that found in the old text "Introduction to General Relativity", by Adler, Bazin and Schiffer. The plan of the analysis is as follows. * Model the planetary orbits as geodesics in the (exterior) Schwarzschild spacetime. * Compute the geodesic equations. * Simplify them using symmetries and first integrals. * Isolate the differential equation expressing the radial coordinate as a function of …

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The Spacetime Geometry Of A Null Electromagnetic Field, Charles G. Torre Feb 2014

The Spacetime Geometry Of A Null Electromagnetic Field, Charles G. Torre

Charles G. Torre

We give a set of local geometric conditions on a spacetime metric which are necessary and sufficient for it to be a null electrovacuum, that is, the metric is part of a solution to the Einstein-Maxwell equations with a null electromagnetic field. These conditions are restrictions on a null congruence canonically constructed from the spacetime metric, and can involve up to five derivatives of the metric. The null electrovacuum conditions are counterparts of the Rainich conditions, which geometrically characterize non-null electrovacua. Given a spacetime satisfying the conditions for a null electrovacuum, a straightforward procedure builds the null electromagnetic field from …

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Paleolimnological Analysis Of The History Of Metals Contamination In The Great Salt Lake, Utah, Wayne A. Wurtsbaugh, Katrina Moser, Peter R. Leavitt Jan 2014

Paleolimnological Analysis Of The History Of Metals Contamination In The Great Salt Lake, Utah, Wayne A. Wurtsbaugh, Katrina Moser, Peter R. Leavitt

Wayne A. Wurtsbaugh

Three sediment cores from the Great Salt Lake were analyzed to determine the magnitude and timing for the deposition of 21 metal contaminants. In the main lake (Gilbert Bay) concentrations of copper, lead, zinc, cadmium, silver, molybdenum, tin, mercury and others began increasing in the sediments in the late 1800s or early 1900s and peaked in the 1950s. These increases were coincident with increases in mining and smelting activities for these metals in Utah. Contamination indices in the 1950s were 20-60 fold above background concentrations for silver, copper, lead and molybdenum, and <15-fold for most other metals. Since the 1950s, concentrations of most metals in the sediments have decreased 2-5 fold coincident with decreases in mining and improved smelting technologies. Nevertheless concentrations for many metals in surficial sediments are still above acceptable criteria established for freshwater ecosystems. In contrast to most metals, concentrations of selenium and arsenic were stable or increasing slightly in the Gilbert Bay sediments. In a coring site located in Farmington Bay near an EPA Superfund Site discharge canal, concentrations of metals were high and showed no indication of decreasing in more recent sediments. Surficial sediments from additional sites in the Great Salt Lake indicated that metals were more concentrated towards the southern end of the lake where the primary sources of contamination were located.

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Research Report: Water User Dimensions Of Meter Implementation On Secondary Pressurized Irrigation Systems, Joanna Endter-Wada, Diana Glenn, Clayton Lewis, Roger Kjelgren, Christopher Neale Apr 2013

Research Report: Water User Dimensions Of Meter Implementation On Secondary Pressurized Irrigation Systems, Joanna Endter-Wada, Diana Glenn, Clayton Lewis, Roger Kjelgren, Christopher Neale

Joanna Endter-Wada

Weber Basin Water Conservancy District (District) secured Bureau of Reclamation funding in spring 2011 to install individual secondary water meters at residential connections in order to implement water efficiency and accountability measures included in the District’s Water Conservation Plan (Weber Basin Water Conservancy District, 2010). Initially, the District will not use the meters for billing water use but, instead, will use them to help the District determine if end users are exceeding their contracted allotment of water and to promote water use accountability.The purpose of the study titled “Water User Dimensions of Meter Implementation on Secondary Pressurized Irrigation Systems” conducted …

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Beef Production And Consumption: Sustainable Alternatives, Roslynn Brain Mar 2013

Beef Production And Consumption: Sustainable Alternatives, Roslynn Brain

Roslynn Brain

Sustainable living involves choosing a lifestyle with minimal environmental impacts. The ultimate goal is to leave future generations with a healthier environment than the one we were born into. How can we do that with beef consumption? Beef is part of American culture, so is there a way to make wiser choices when it comes to purchasing beef ? The short answer is, yes!

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Can The Causeway In The Great Salt Lake Be Used To Manage Salinity, Sarah E. Null, Wayne A. Wurtsbaugh, Craig Miller Jan 2013

Can The Causeway In The Great Salt Lake Be Used To Manage Salinity, Sarah E. Null, Wayne A. Wurtsbaugh, Craig Miller

Wayne A. Wurtsbaugh

No abstract provided.

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Urban Edibles: Ornamentals, Roslynn Brain Jan 2013

Urban Edibles: Ornamentals, Roslynn Brain

Roslynn Brain

Who says the only place for city dwellers to pick up their daily dose of vegetables is the local farmers market or grocer? Much of the produce you need and enjoy is available to you in your own backyard and, better yet, is free of cost! Urban foraging is the art of finding, identifying and collecting wild edibles in everyday urban settings. From delicious fruits to weeds you would never in your wildest dreams think to eat, cities are full of handpicked eating opportunities!

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Effect Of Sudden Stratospheric Warmingon Lunar Tidal Modulation Of The Equatorial Electrojet, J. Park, H. Luhr, M. Kunze, Bela G. Fejer, K. W. Min Mar 2012

Effect Of Sudden Stratospheric Warmingon Lunar Tidal Modulation Of The Equatorial Electrojet, J. Park, H. Luhr, M. Kunze, Bela G. Fejer, K. W. Min

Bela G. Fejer

[1] Using the equatorial electrojet (EEJ) peak current intensity as deduced from CHAMP magnetic observations from the years 2001 through 2009, we investigated the relationship between sudden stratospheric warming (SSW) and lunitidal signatures in the tropical ionosphere. There is a practically one-to-one correspondence between midwinter SSW periods and the strongest 13 day modulation of the EEJ strength as observed by CHAMP. That is, all the midwinter SSW periods from December 2001 to August 2009 were accompanied by an enhanced 13 day modulation of the EEJ strength. No other geophysical phenomenon brought about as strong a 13 day modulation as those …

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Investigating Mountain Waves In Mtm Image Data At Cerro Pachon, Chile, Neal R. Criddle, M. J. Taylor, P.-D. Pautet, Y. Zhao, G. Swenson, A. Liu Jan 2012

Investigating Mountain Waves In Mtm Image Data At Cerro Pachon, Chile, Neal R. Criddle, M. J. Taylor, P.-D. Pautet, Y. Zhao, G. Swenson, A. Liu

Neal R Criddle

Gravity waves are important drivers of chemical species mixing, energy and momentum transfer into the MLT (~80 - 100 km) region. As part of a collaborative program involving instruments from several institutions Utah State University has operated a Mesospheric Temperature Mapper (MTM) at the new Andes Lidar Observatory (ALO) on Cerro Pachon (30.2°S, 70.7°W) Since August 2009. A primary goal of this program is to quantify the impact of mountain waves on the MLT region. The Andes region is an excellent natural laboratory for investigating gravity wave influences on the MLT region, especially the study of mountain waves, created by …

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The Density Factor In The Synthesis Of Carbon Nanotube Forest By Injection Chemical Vapor Deposition, R. W. Call, C. G. Read, C. Mart, T. -C. Shen Jan 2012

The Density Factor In The Synthesis Of Carbon Nanotube Forest By Injection Chemical Vapor Deposition, R. W. Call, C. G. Read, C. Mart, T. -C. Shen

T. -C. Shen

Beneath the seeming straight-forwardness of growing carbon nanotube(CNT) forests by the injection chemical vapor deposition(CVD) method, control of the forest morphology on various substrates is yet to be achieved. Using ferrocene dissolved in xylene as the precursor, we demonstrate that the concentration of ferrocene and the injection rate of the precursor dictate the CNT density of these forests. However, CNT density will also be affected by the substrates and the growth temperature which determine the diffusion of the catalyst adatoms. The CNT growth rate is controlled by the temperature and chemical composition of the gases in the CVD reactor. We …

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Windowed Pq-Grams For Approximate Joins Of Data-Centric Xml, Nikolaus Augsten, Michael H. Böhlen, Curtis Dyreson, Johann Gamper Jan 2012

Windowed Pq-Grams For Approximate Joins Of Data-Centric Xml, Nikolaus Augsten, Michael H. Böhlen, Curtis Dyreson, Johann Gamper

Curtis Dyreson

In data integration applications, a join matches elements that are common to two data sources. Since elements are represented slightly different in each source, an approximate join must be used to do the matching. For XML data, most existing approximate join strategies are based on some ordered tree matching technique, such as the tree edit distance. In data-centric XML, however, the sibling order is irrelevant, and two elements should match even if their subelement order varies. Thus, approximate joins for data-centric XML must leverage unordered tree matching techniques. This is computationally hard since the algorithms cannot rely on a predefined …

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Adding Temporal Constraints To Xml Schema, Faiz Currim, Sabah Currim, Curtis Dyreson, Richard T. Snodgrass, Steven W. Thomas, Rui Zhang Jan 2012

Adding Temporal Constraints To Xml Schema, Faiz Currim, Sabah Currim, Curtis Dyreson, Richard T. Snodgrass, Steven W. Thomas, Rui Zhang

Curtis Dyreson

If past versions of XML documents are retained, what of the various integrity constraints defined in XML Schema on those documents? This paper describes how to interpret such constraints as sequenced constraints, applicable at each point in time. We also consider how to add new variants that apply across time, so-called non-sequenced constraints. Our approach supports temporal documents that vary over both valid and transaction time, whose schema can vary over transaction time. We do this by replacing the schema with a (possibly time-varying) temporal schema and replacing the document with a temporal document, both of which are upward compatible …

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Observations Of The Vertical Ion Drift In The Equatorial Ionosphere During The Solar Minimum Period Of 2009, R. A. Stoneback, R. A. Heelis, A. G. Burrell, W. R. Coley, Bela G. Fejer, E. Pacheco Dec 2011

Observations Of The Vertical Ion Drift In The Equatorial Ionosphere During The Solar Minimum Period Of 2009, R. A. Stoneback, R. A. Heelis, A. G. Burrell, W. R. Coley, Bela G. Fejer, E. Pacheco

Bela G. Fejer

[1] The extended solar minimum conditions in 2008 and 2009 presented an opportunity to investigate the ionosphere at lower solar activity levels than previously observed. The Coupled Ion Neutral Dynamics Investigation (CINDI) Ion Velocity Meter (IVM) instrument onboard the Communication/Navigation Outage Forecasting System is used to construct the median meridional (vertical) ion drifts, ion densities, and O+ concentrations during periods of low geomagnetic activity for four characteristic seasons each year spanning late 2008 to 2010. The presence of a large semidiurnal component in the ion drift variation at the equator produced significant differences from typical ionospheric conditions. Instead of upward …

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New Insights Into The Outlet Conditions Of Late Pleistocene Lake Bonneville, Southeastern Idaho, Usa, Susanne U. Janecke, Robert Q. Oaks Jr. Nov 2011

New Insights Into The Outlet Conditions Of Late Pleistocene Lake Bonneville, Southeastern Idaho, Usa, Susanne U. Janecke, Robert Q. Oaks Jr.

Susanne U. Janecke

Geologic, geomorphic, and geophysical analyses of landforms, sediments, and structures in northern Cache Valley, USA, document a revised history of flooding and recession of Lake Bonneville, the world's premier pluvial lake. Crosscutting relationships suggest that the Riverdale fault produced a surface-rupturing earthquake ∼25 km southeast of Zenda shortly before, during, or after the Bonneville flood, as well as possible younger surface ruptures. Thus fluctuating stresses and pore pressure induced by changing lake levels may have triggered a large earthquake that, in turn, triggered the Bonneville flood. The flood scoured ∼25 km of Cache and Marsh Valleys and activated landslides during …

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Enhanced Lunar Semidiurnal Equatorial Vertical Plasma Drifts During Sudden Stratospheric Warmings, Bela G. Fejer, B. D. Tracy, J. L. Chau Nov 2011

Enhanced Lunar Semidiurnal Equatorial Vertical Plasma Drifts During Sudden Stratospheric Warmings, Bela G. Fejer, B. D. Tracy, J. L. Chau

Bela G. Fejer

[1] Large scale electrodynamic and plasma density variations in the low latitude ionosphere have recently been associated with sudden stratospheric warming (SSW) events. We present average patterns of largely enhanced lunar semidiurnal equatorial vertical plasma drift perturbations during arctic winter low and high solar flux SSW events. These perturbations play a dominant role in the electrodynamic response of the low latitude ionosphere to SSWs. Our models indicate that the amplitudes of the enhanced lunar semidiurnal drifts are strongly local time and solar flux dependent, with largest values during early morning low solar flux SSW periods. These results suggest that ionospheric …

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Envs 6900: Graduate Student Publishing Seminar, Charles Romesburg Jun 2011

Envs 6900: Graduate Student Publishing Seminar, Charles Romesburg

Charles Romesburg

Course syllabus for ENVS 6900, Graduate Student Publishing Seminar describes course (purpose, format, etc.) and provides lists of readings and magazine outlets for student writings.

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Building An Interdisciplinary Research Program In Water Conservation: Approach, Preliminary Findings, And Next Steps, David E. Rosenberg, Joanna Endter-Wada, Arthur Caplan, Diana T. Glenn Apr 2011

Building An Interdisciplinary Research Program In Water Conservation: Approach, Preliminary Findings, And Next Steps, David E. Rosenberg, Joanna Endter-Wada, Arthur Caplan, Diana T. Glenn

Diana T. Glenn

Effective urban water conservation programs must harness a synergy of new technologies, public policies, social cost pricing, information dissemination, citizen engagement, and coordinated actions across decision making scales. Together, these factors affect the volume of water an individual user ultimately saves and the overall success of a conservation program or programs. Over the past 18 months, we have started building an interdisciplinary research program in urban water conservation to quantify and assess the effects of these interconnected factors to motivate citizen engagement. We have interviewed water utility managers and conservation coordinators across the state of Utah, held focus groups with …

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Lettau Affect Colloquium: Or Seeing Natural Philosophy With Len, L. F. Hall Feb 2011

Lettau Affect Colloquium: Or Seeing Natural Philosophy With Len, L. F. Hall

Leonard F. Hall

I was a Senior-Grad student in the Department of Meteorology at the University of Wisconsin at Madison on 19 December 1969. After purchasing a camera to photograph motorcycle trips, I returned to the 13th floor of the Meteorology and Space Science building in time to attend the annual slide show presented by Professor Heinz H. Lettau. Slides were collected from department members to augment his own and Dr. Lettau organized and presented the set. It was a feast of previously unnoticed phenomena that enriched my life. This presentation of photos and composites celebrates a rich contribution of a Doktor Vater …

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Seasonal Variability And Dynamics Of Mesospheric Gravity Waves Over The Andes, Neal R. Criddle, M. J. Taylor, P.-D. Pautet, Y. Zhao Jan 2011

Seasonal Variability And Dynamics Of Mesospheric Gravity Waves Over The Andes, Neal R. Criddle, M. J. Taylor, P.-D. Pautet, Y. Zhao

Neal R Criddle

The ALO is a new facility developed for atmospheric research, located at the foot of the Andes mountain range in Cerro Pachon, Chile (30.2°S, 70.7°W). As part of a collaborative program, Utah State has a Mesospheric Temperature Mapper (MTM) on site, which is used to study short period gravity wave dynamics and temperature variations in the mesosphere-lower thermosphere region. The MTM began taking measurements of the OH(6,2) and O2(0,1) spectral bands in August 2009 and a complete profile of seasonal variation in gravity wave characteristics has been created for August 2009 through August 2010 using the OH(6,2) Band. The primary …

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New Symbolic Tools For Differential Geometry, Gravitation, And Field Theory (Extended Version), Charles G. Torre, Ian M. Anderson Jan 2011

New Symbolic Tools For Differential Geometry, Gravitation, And Field Theory (Extended Version), Charles G. Torre, Ian M. Anderson

Charles G. Torre

DifferentialGeometry is a Maple software package which symbolically performs fundamental operations of calculus on manifolds, differential geometry, tensor calculus, Lie algebras, Lie groups, transformation groups, jet spaces, and the variational calculus. These capabilities, combined with dramatic recent improvements in symbolic approaches to solving algebraic and differential equations, have allowed for development of powerful new tools for solving research problems in gravitation and field theory. The purpose of this paper is to describe some of these new tools and present some advanced applications involving: Killing vector fields and isometry groups, Killing tensors and other tensorial invariants, algebraic classification of curvature, and …

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