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2004

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Articles 3391 - 3420 of 4447

Full-Text Articles in Physical Sciences and Mathematics

Synthesis Of The Novel Crown Ether 1 ,9-Dioxa-4,6-Dithiacycloundecane, Cassie Booth Jan 2004

Synthesis Of The Novel Crown Ether 1 ,9-Dioxa-4,6-Dithiacycloundecane, Cassie Booth

Capstone Research Projects

Attempts to produce novel crowns, incorporating a thioacetal fragment, were made via two synthetic pathways. Despite the well-established reactions found in path A (see figure 3), this method failed to produce the desired crown. Path B, a one-pot reaction originally designed to close rings via the addition of a thioacetal fragment, yielded an oily product that was purified with a silica gel column (48.3% yield). Initial analysis by 1H NMR showed a structure consistent with that of the desired crown (figure 2). Mass spectroscopy was used to verify product identity, confirming the creation of our target molecule 1 ,9-dioxa-4,6-dithiacycloundecane.

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Calculating The Unrestricted Partition Function Towards An Investigation Of Its Arithmetic Properties, Robert Jacobson Jan 2004

Calculating The Unrestricted Partition Function Towards An Investigation Of Its Arithmetic Properties, Robert Jacobson

Capstone Research Projects

No abstract provided.

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Environmental Swap Energy And Role Of Configurational Entropy In Transfer Of Small Molecules From Water Into Alkanes, Pavel Smejtek, Robert Campbell Word Jan 2004

Environmental Swap Energy And Role Of Configurational Entropy In Transfer Of Small Molecules From Water Into Alkanes, Pavel Smejtek, Robert Campbell Word

Physics Faculty Publications and Presentations

We studied the effect of segmented solvent molecules on the free energy of transfer of small molecules from water into alkanes (hexane, heptane, octane, decane, dodecane, tetradecane, and hexadecane). For these alkanes we measured partition coefficients of benzene, 3-methylindole (3MI), 2,3,4,6-tetrachlorophenol (TeCP), and 2,4,6-tribromophenol (TriBP) at 3, 11, 20, 3, and 47 °C. For 3MI, TeCP, and TriBP the dependence of free energy of transfer on length of alkane chains was found to be very different from that for benzene. In contrast to benzene, the energy of transfer for 3MI, TeCP, and TriBP was independent of the number of carbons …

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Electric Discharge: Boundary Conditions, Mostafa Hemmati, Chris Justice Jan 2004

Electric Discharge: Boundary Conditions, Mostafa Hemmati, Chris Justice

Journal of the Arkansas Academy of Science

The electron gas in electric discharge can be described by a set of one-dimensional fluid dynamical equations. The fundamental equations are those of a three-component (electrons, ions, and neutral particles) fluid, different from the treatment of the problem inplasma physics, a fully ionized two-component case. The leading edge of the wave is treated as a shock front driven mainly by the electron gas pressure. Integrating the one-dimensional global differential equations for mass balance, conservation of momentum and energy, and evaluating the constant of integration at the wave front permits derivation of boundary conditions on electron temperature and electron velocity. Using …

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Impact Of Black Shale Weathering On Sediment Quality, G. M. Ogendi, R. E. Hannigan, Jerry L. Farris, D. Smith Jan 2004

Impact Of Black Shale Weathering On Sediment Quality, G. M. Ogendi, R. E. Hannigan, Jerry L. Farris, D. Smith

Journal of the Arkansas Academy of Science

Weathering of black shales leads to elevated metal concentrations in both surface water and stream sediments. In spite of the recent focus on black shales, few data exist on the ecological impacts of this process particularly on aquatic organisms. The key objective of this study was to determine the impact of trace metal concentrations in sediments upon aquatic organisms. To achieve the above objective, stream sediment samples were collected from streams draining black shale and limestone (used as a reference stream) lithologies located in central Arkansas between June 2003 and January 2004. Trace metal concentrations were measured by the dynamic …

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The Effects Of Multiple Mutations In The Hydrophobic Core Upon The Stability Of Staphylococcal Nuclease, Rebecca L. Danforth Jan 2004

The Effects Of Multiple Mutations In The Hydrophobic Core Upon The Stability Of Staphylococcal Nuclease, Rebecca L. Danforth

Inquiry: The University of Arkansas Undergraduate Research Journal

Previous work in the laboratory of my research advisor, Dr. Wesley Stites, has investigated the core packing of the protein staphylococcal nuclease. The core of a protein is critical in determining a protein's structure and stability. The hydrophobicity of the core has long been thought to be the principal driving force for folding, but recent work in the Stites lab has shown that optimization of van der Waals contacts and minimization of cavities, in our shorthand term, packing, is at least as energetically important. We are building upon this information in our attempt to better pack the protein core. If …

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Correlation Between Atmospheric Co2 Concentration And Vegetation Greenness In North America: Co2 Fertilization Effect, C. Lim, Menas Kafatos, P. Megonigal Jan 2004

Correlation Between Atmospheric Co2 Concentration And Vegetation Greenness In North America: Co2 Fertilization Effect, C. Lim, Menas Kafatos, P. Megonigal

Mathematics, Physics, and Computer Science Faculty Articles and Research

The possibility that rising atmospheric CO2 concentrations are influencing plant growth in contemporary ecosystems has received little attention, and the studies that exist have been done on a small spatial scale. We correlated the monthly rate of relative change in normalized differenced vegetation index (NDVI) from advanced very high resolution radiometer (AVHRR) data to the rate of change in atmospheric CO2 concentration during the natural vegetation growing season for evidence of a possible CO2 fertilization effect on vegetation development. The study addressed seasonal and annual patterns in spatially averaged NDVI for 3 different ecological regions in North America from 1982 …

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Tailwater Recovery Systems For Irrigation: Benefit/Cost Analysis And Water Resource Conservation Technique In Northeast Arkansas, Jennifer L. Bouldin, Nate A. Bickford, H. B. Stroud, G. S. Guha Jan 2004

Tailwater Recovery Systems For Irrigation: Benefit/Cost Analysis And Water Resource Conservation Technique In Northeast Arkansas, Jennifer L. Bouldin, Nate A. Bickford, H. B. Stroud, G. S. Guha

Journal of the Arkansas Academy of Science

Water, one of the earth's most vital resources, is particularly significant in the Arkansas Delta agricultural landscape. While both surface and groundwater are extremely important, 94% of the 26.9 billion L (7.1 billion gal) of water pumped daily from the Alluvial Aquifer is used for agricultural purposes. This common property is subsequently being depleted and sustainable conservation methods are being pursued. State and federal incentive programs encourage the use of a tailwater recovery system in agricultural irrigation. With the use of a complete recovery system, benefits include not only government incentives for wetland habitat, but reduced groundwater use and decreased …

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Hells Canyon National Recreation Area Case Study, Jim Martin, Doug Cannon, University Of Colorado Boulder. Natural Resources Law Center Jan 2004

Hells Canyon National Recreation Area Case Study, Jim Martin, Doug Cannon, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

30, A-8, B-5 p. : ill., map

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King Range National Conservation Area Case Study, Ann Morgan, Doug Cannon, University Of Colorado Boulder. Natural Resources Law Center Jan 2004

King Range National Conservation Area Case Study, Ann Morgan, Doug Cannon, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

25, A-2, B-4, C-2 p. : ill., map

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Protective Designations On Federal Lands: Case Studies Of National Conservation Areas, National Monuments, National Parks, National Recreation Areas, And Wilderness Areas, University Of Colorado Boulder. Natural Resources Law Center Jan 2004

Protective Designations On Federal Lands: Case Studies Of National Conservation Areas, National Monuments, National Parks, National Recreation Areas, And Wilderness Areas, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

18, A-4 p.

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Private Lands Conservation In The British Virgin Islands, Joan Marsan, University Of Colorado Boulder. Natural Resources Law Center Jan 2004

Private Lands Conservation In The British Virgin Islands, Joan Marsan, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

46 p. ; 28 cm

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Private Lands Conservation In The Dominican Republic, Julie Truelsen, University Of Colorado Boulder. Natural Resources Law Center Jan 2004

Private Lands Conservation In The Dominican Republic, Julie Truelsen, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

56 p. ; 28 cm

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Private Lands Conservation In Puerto Rico, Elizabeth Mccormack, University Of Colorado Boulder. Natural Resources Law Center Jan 2004

Private Lands Conservation In Puerto Rico, Elizabeth Mccormack, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

41 p. ; 28 cm

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Private Lands Conservation In The Commonwealth Of The Northern Mariana Islands, Gregg De Bie, University Of Colorado Boulder. Natural Resources Law Center Jan 2004

Private Lands Conservation In The Commonwealth Of The Northern Mariana Islands, Gregg De Bie, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

68 p. ; 28 cm

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Private Lands Conservation In Jamaica, Katharine Stone, University Of Colorado Boulder. Natural Resources Law Center Jan 2004

Private Lands Conservation In Jamaica, Katharine Stone, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

1, 35 leaves ; 28 cm

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A University Online Portal For Enterprise Learning Communities, Marco Neumann, Ciaran Mcdonnell, Deirdre Hogan, Carol Reinsford, Stefan Decker Jan 2004

A University Online Portal For Enterprise Learning Communities, Marco Neumann, Ciaran Mcdonnell, Deirdre Hogan, Carol Reinsford, Stefan Decker

Conference papers

This paper describes the Programme for University Industry Interface Semantic Web Portal project that supports the efforts in enterprise training units to upskill the employee in the company and facilitates the creation and reuse of knowledge in online communities. The main purpose of this project is to support on-line learning communities and monitor the changing needs and skills of the work force in enterprise environments.

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First Upper Limits From Ligo On Gravitational Wave Bursts, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Joseph D. Romano, Cristina V. Torres Jan 2004

First Upper Limits From Ligo On Gravitational Wave Bursts, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Joseph D. Romano, Cristina V. Torres

Physics and Astronomy Faculty Publications and Presentations

We report on a search for gravitational wave bursts using data from the first science run of the Laser Interferometer Gravitational Wave Observatory (LIGO) detectors. Our search focuses on bursts with durations ranging from 4 to 100 ms, and with significant power in the LIGO sensitivity band of 150 to 3000 Hz. We bound the rate for such detected bursts at less than 1.6 events per day at a 90% confidence level. This result is interpreted in terms of the detection efficiency for ad hoc waveforms (Gaussians and sine Gaussians) as a function of their root-sum-square strain hrss; typical sensitivities …

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Analysis Of First Ligo Science Data For Stochastic Gravitational Waves, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Joseph D. Romano Jan 2004

Analysis Of First Ligo Science Data For Stochastic Gravitational Waves, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Joseph D. Romano

Physics and Astronomy Faculty Publications and Presentations

We present the analysis of between 50 and 100 h of coincident interferometric strain data used to search for and establish an upper limit on a stochastic background of gravitational radiation. These data come from the first LIGO science run, during which all three LIGO interferometers were operated over a 2-week period spanning August and September of 2002. The method of cross correlating the outputs of two interferometers is used for analysis. We describe in detail practical signal processing issues that arise when working with real data, and we establish an observational upper limit on a f−3 power spectrum of …

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Geology Across And Under The Western Snake River Plain, Idaho: Owyhee Mountains To The Boise Foothills, Spencer H. Wood Jan 2004

Geology Across And Under The Western Snake River Plain, Idaho: Owyhee Mountains To The Boise Foothills, Spencer H. Wood

Geosciences Faculty Publications and Presentations

This 1-day field trip is a transect across the western Snake River Plain (fig. 1). The western plain is a continental- rift structure, 300 km long and 70 km wide. It is bounded and internally faulted by northwest-trending normal faults. The western Snake River Plain has a different orientation and structure than the eastern plain. The eastern plain is a curious downwarp related to magmatism and extension along the track of the Yellowstone hot spot (fig. 2). The faulted basin of the western plain began forming about 12 m.y. ago, and much of the relief was completed by 9 Ma. …

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Ogallala Aquifer, Robert F. Diffendal Jr. Jan 2004

Ogallala Aquifer, Robert F. Diffendal Jr.

School of Natural Resources: Faculty Publications

The Ogallala Aquifer, or High Plains Aquifer, is a porous body of complex sediments and sedimentary rock formations that conducts groundwater and yields significant quantities of water to wells and springs. The principal sediments and rocks of the aquifer range in age from 33 million years old to sediments being deposited today, but the majority is less than 12 million-years old. Much of the aquifer is composed of the Ogallala Group or Formation. The dominant sediments in the Ogallala and the other hydrogeologic units in the aquifer are riverand wind-deposited sands. The aquifer underlies about 174,000 square miles of the …

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Topographic Maps, Robert F. Diffendal Jr. Jan 2004

Topographic Maps, Robert F. Diffendal Jr.

School of Natural Resources: Faculty Publications

Topographic maps show the general configuration of the land surface, including its relief and the position of natural and man-made features. The configuration is shown commonly by contour lines, imaginary lines connecting all points of equal elevation on the earth's surface above or below a datum plane such as mean sea level. When the land slope is steeper the contour lines are closer together. Topographic maps at scales of one inch to a mile or greater (shown as 1:63,360 on the map) are used in many ways. They are particularly important in preparation of various types of geologic maps and …

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Special Section On The Algorithmics Of Software Model Checking — Introductory Paper, Matthew Dwyer, Stefan Leue Jan 2004

Special Section On The Algorithmics Of Software Model Checking — Introductory Paper, Matthew Dwyer, Stefan Leue

School of Computing: Faculty Publications

The term “software model checking” has recently been coined to refer to a flourishing area of research in software verification – the formal, automated analysis of program source code. Software model checking is considered an important application of classical model checking, where the model of a software system is analyzed in an automated fashion for compliance with a property specification. While classical model checking assumes the existence of an abstract model of the software system to be analyzed, in software model checking the emphasis is on directly analyzing program code given in a standard programming language, such as Java or …

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Front Matter Jan 2004

Front Matter

Journal of the Iowa Academy of Science: JIAS

No abstract provided.

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Back Cover Jan 2004

Back Cover

Journal of the Iowa Academy of Science: JIAS

No abstract provided.

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Front Matter Jan 2004

Front Matter

Journal of the Iowa Academy of Science: JIAS

No abstract provided.

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Back Cover Jan 2004

Back Cover

Journal of the Iowa Academy of Science: JIAS

No abstract provided.

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Disjoint Np-Pairs, Christian Glasser, Alan L. Selman, Samik Sengupta, Liyu Zhang Jan 2004

Disjoint Np-Pairs, Christian Glasser, Alan L. Selman, Samik Sengupta, Liyu Zhang

Computer Science Faculty Publications and Presentations

We study the question of whether the class DisjNP of disjoint pairs (A, B) of NP-sets contains a complete pair. The question relates to the question of whether optimal proof systems exist, and we relate it to the previously studied question of whether there exists a disjoint pair of NP-sets that is NP-hard. We show under reasonable hypotheses that nonsymmetric disjoint NP-pairs exist, which provides additional evidence for the existence of P-inseparable disjoint NP-pairs. We construct an oracle relative to which the class of disjoint NP-pairs does not have a complete pair; an oracle relative to which …

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Experimental Studies On Nucleation, Nanoparticle's Formation And Polymerization From The Vapor Phase, Victor Maher Abdelsayed Jan 2004

Experimental Studies On Nucleation, Nanoparticle's Formation And Polymerization From The Vapor Phase, Victor Maher Abdelsayed

Theses and Dissertations

This research is divided into three major parts. In part I, the critical supersaturations required for the homogeneous nucleation of 2,2,2-trifluorothanol (TFE) vapor have been measured over a temperature range (266-296 K) using an upward thermal diffusion cloud chamber (DCC). The measured supersaturations are in agreement with the predictions of both the classical and the scaled theory of nucleation. Moreover, the condensation of supersaturated TFE vapor on laser-vaporized magnesium nanoparticles has been studied under different experimental conditions, such as the supersaturation, the pressure and the electric field. In part II, the laser vaporization controlled condensation (LVCC) technique was used to …

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Gas Phase Studies Of Molecular Clusters Containing Metal Cations, And The Ion Mobility Of Styrene Oligomers, Edreese Housni Alsharaeh Jan 2004

Gas Phase Studies Of Molecular Clusters Containing Metal Cations, And The Ion Mobility Of Styrene Oligomers, Edreese Housni Alsharaeh

Theses and Dissertations

This study is divided into three parts. Part I deals with the mechanism of the self-initiated polymerization (or thermal polymerization) of styrene in the gas phase. In this work, we present the first direct evidence for the thermally self-initiated polymerization of styrene in the gas phase. Our approach is based on on-line analysis of the gas phase Oligomers by mass-selected ion mobility. The mobility measurements provide structural information on the ionized oligomers based on their collision cross-sections (Ω) which depend on the geometric shapes of the ions. Theoretical calculations of possible structural candidates of the Oligomers ions are then used …

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