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Preliminary Results From The Russian-American Gallium Experiment Cr-Neutrino Source Measurement, S. R. Elliott, J. N. Abdurashitov, T. J. Bowles, M. L. Cherry, B. T. Cleveland, T. Daily, R. Davis, V. N. Gavrin, S. V. Girin, V. V. Gorbatschev, A. O. Gusev, A. V. Kalikhov, N. G. Khairnasov, V. N. Karaulov, T. V. Knodel, V. N. Kornoukhov, Yu S. Khomyakov, K. Lande, C. K. Lee, V. L. Levitin, V. I. Maev, I. N. Mirmov, P. I. Nazarenko, J. S. Nico, A. M. Pshukov, A. M. Shalagin, A. A. Shikhin, V. S. Shkol'nik, N. V. Skorikov, W. A. Teasdale, E. P. Veretenkin, V. M. Vermul, D. L. Wark Jan 1996

Preliminary Results From The Russian-American Gallium Experiment Cr-Neutrino Source Measurement, S. R. Elliott, J. N. Abdurashitov, T. J. Bowles, M. L. Cherry, B. T. Cleveland, T. Daily, R. Davis, V. N. Gavrin, S. V. Girin, V. V. Gorbatschev, A. O. Gusev, A. V. Kalikhov, N. G. Khairnasov, V. N. Karaulov, T. V. Knodel, V. N. Kornoukhov, Yu S. Khomyakov, K. Lande, C. K. Lee, V. L. Levitin, V. I. Maev, I. N. Mirmov, P. I. Nazarenko, J. S. Nico, A. M. Pshukov, A. M. Shalagin, A. A. Shikhin, V. S. Shkol'nik, N. V. Skorikov, W. A. Teasdale, E. P. Veretenkin, V. M. Vermul, D. L. Wark

Faculty Publications

The Russian-American Gallium Experiment has been collecting solar neutrino data since early 1990. The flux measurement of solar neutrinos is well below that expected from solar models. We discuss the initial results of a measurement of experimental efficiencies by exposing the gallium target to neutrinos from an artificial source. The capture rate of neutrinos from this source is very close to that which is expected. The result can be expressed as a ratio of the measured capture rate to the anticipated rate from the source activity. This ratio is 0.93 + 0.15, - 0.17 where the systematic and statistical errors …

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The Macho Project Large Magellanic Cloud Variable Star Inventory. Iv. New R Coronae Borealis Stars, C. Alcock, R. A. Allsman, D. R. Alves, T. S. Axelrod, A. Decker, D. P. Bennett, G. C. Clayton, K. H. Cook, K. C. Freeman, K. Griest, J. A. Guern, D. Kilkenny, M. J. Lehner, S. L. Marshall, D. Minniti, B. A. Peterson, M. R. Pratt, P. J. Quinn, A. W. Rodgers, C. W. Stubbs, W. Sutherland, D. Welch Jan 1996

The Macho Project Large Magellanic Cloud Variable Star Inventory. Iv. New R Coronae Borealis Stars, C. Alcock, R. A. Allsman, D. R. Alves, T. S. Axelrod, A. Decker, D. P. Bennett, G. C. Clayton, K. H. Cook, K. C. Freeman, K. Griest, J. A. Guern, D. Kilkenny, M. J. Lehner, S. L. Marshall, D. Minniti, B. A. Peterson, M. R. Pratt, P. J. Quinn, A. W. Rodgers, C. W. Stubbs, W. Sutherland, D. Welch

Faculty Publications

We report the discovery of two new R Coronae Borealis (RGB) stars in the LMC using the MACHO project photometry database. The identification of both stars has been confirmed spectroscopically. One is a cool RGB star (Teff ∼ 5000 K), characterized by very strong Swan bands of C2 and violet bands of CN, and weak or absent Bahner lines, G band, and 12C13C bands. The second star is an example of a hot RGB star, of which only three were previously known to exist in the Galaxy and none in the LMC. Its spectrum is characterized by several G n …

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Lattice Dynamics Of Ii-Vi Materials Using The Adiabatic Bond-Charge Model, B. Rajput, D. Browne Jan 1996

Lattice Dynamics Of Ii-Vi Materials Using The Adiabatic Bond-Charge Model, B. Rajput, D. Browne

Faculty Publications

We extend the adiabatic bond-charge model, originally developed for group IV semiconductors and III-V compounds, to study phonons in more ionic II-VI compounds with a zinc-blende structure. Phonon spectra, density of states, and specific heats are calculated for six II-VI compounds and compared with both experimental data and the results of other models. We show that the six-parameter bond-charge model gives a good description of the lattice dynamics of these materials. We also discuss trends in the parameters with respect to the ionicity and metallicity of these compounds. © 1996 The American Physical Society.

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First-Principles Lcgo Calculation Of The Magneto-Optical Properties Of Nickel And Iron, Neeraj Mainkar, D. Browne, J. Callaway Jan 1996

First-Principles Lcgo Calculation Of The Magneto-Optical Properties Of Nickel And Iron, Neeraj Mainkar, D. Browne, J. Callaway

Faculty Publications

We report a first-principles, self-consistent, all-electron, linear combination of Gaussian orbitals calculation of a comprehensive collection of magneto-optical properties of nickel and iron based on density-functional theory. Among the many magneto-optical effects, we have studied the equatorial Kerr effect for absorption in the optical as well as soft-x-ray region, where it is called x-ray magnetic linear dichroism. In the optical region the effect is of the order of 2% while in the x-ray region it is of the order of 1% for the incident angles considered. In addition, the polar Kerr effect, x-ray magnetic circular dichroism, and total x-ray absorption …

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The Russian-American Gallium Experiment (Sage) Cr Neutrino Source Measurement, J. N. Abdurashitov, V. N. Gavrin, S. V. Girin, V. V. Gorbachev, T. V. Ibragimova, A. V. Kalikhov, N. G. Khairnasov, T. V. Knodel, V. N. Kornoukhov, I. N. Mirmov, A. A. Shikhin, E. P. Veretenkin, V. M. Vermul, V. E. Yants, G. T. Zatsepin, T. J. Bowles, J. S. Nico, W. A. Teasdale, D. L. Wark, M. L. Cherry, V. N. Karaulov, V. L. Levitin, V. I. Maev, P. I. Nazarenko, V. S. Shkol-Nik, N. V. Skorikov, B. T. Cleveland, T. Daily, R. Davis, K. Lande, C. K. Lee, P. W. Wildenhain, Y. U.S. Khomyakov Jan 1996

The Russian-American Gallium Experiment (Sage) Cr Neutrino Source Measurement, J. N. Abdurashitov, V. N. Gavrin, S. V. Girin, V. V. Gorbachev, T. V. Ibragimova, A. V. Kalikhov, N. G. Khairnasov, T. V. Knodel, V. N. Kornoukhov, I. N. Mirmov, A. A. Shikhin, E. P. Veretenkin, V. M. Vermul, V. E. Yants, G. T. Zatsepin, T. J. Bowles, J. S. Nico, W. A. Teasdale, D. L. Wark, M. L. Cherry, V. N. Karaulov, V. L. Levitin, V. I. Maev, P. I. Nazarenko, V. S. Shkol-Nik, N. V. Skorikov, B. T. Cleveland, T. Daily, R. Davis, K. Lande, C. K. Lee, P. W. Wildenhain, Y. U.S. Khomyakov

Faculty Publications

The solar neutrino capture rate measured by SAGE is well below that predicted by solar models. To check the overall experimental efficiency, we exposed 13 tonnes of Ga metal to a reactor-produced 517 kCi source of 51Cr. The ratio of the measured production rate to that predicted from the source activity is 0.95+/-0.11\(stat\)+0.05/-0.08\(syst\). This agreement verifies that the experimental efficiency is measured correctly, establishes that there are no unknown systematic errors at the 10% level, and provides considerable evidence for the reliability of the solar neutrino measurement. © 1996 The American Physical Society.

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Isotopic Evolution Of The Tonga Arc During Lau Basin Rifting; Evidence From The Volcaniclastic Record, Peter D. Clift, Pieter Z. Vroon Jan 1996

Isotopic Evolution Of The Tonga Arc During Lau Basin Rifting; Evidence From The Volcaniclastic Record, Peter D. Clift, Pieter Z. Vroon

Faculty Publications

New Pb, Sr and Nd isotope data from volcaniclastic sediments recovered from the Tonga forearc and Lau Basin permit the isotopic evolution of a section of this arc system, next to the modern island of Ata, to be traced through the backarc basin rifting process from 7·0 Ma to the present. The new data suggest that the isotopic character of the mantle wedge remains constant, and of Pacific mid-ocean ridge basalt (MORB) character, during the early rifting phase. The isotopic evidence supports trace element data in showing an increase in the sediment contribution to arc petrogenesis about 2-3 m.y. after …

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Pervanadate Activation Of Intracellular Kinases Leads To Tyrosine Phosphorylation And Shedding Of Syndecan-1, Jane Reiland, Vanessa L. Ott, Connie S. Lebakken, Charles Yeaman, James Mccarthy, Alan C. Rapraeger Jan 1996

Pervanadate Activation Of Intracellular Kinases Leads To Tyrosine Phosphorylation And Shedding Of Syndecan-1, Jane Reiland, Vanessa L. Ott, Connie S. Lebakken, Charles Yeaman, James Mccarthy, Alan C. Rapraeger

Faculty Publications

Syndecan-1 is a transmembrane haparan sulphate proteoglycan that binds extracellular matrices and growth factors, making it a candidate to act between these regulatory molecules and intracellular signalling pathways. It has a highly conserved transmembrane/cytoplasmic domain that contains four conserved tyrosines. One of these is in a consensus sequence for tyrosine kinase phosphorylation. As an initial step to investigating whether or not phosphorylation of these tyrosines is part of a signal-transduction pathway, we have monitored the tyrosine phosphorylation of syndecan-1 by cytoplasmic tyrosine kinases in intact cells. Tyrosine phosphorylation of syndecan-1 is observed when NMuMG cells are treated with sodium orthovanadate …

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A Low-Co2-Inducible Gene Encoding An Alanine:Α-Ketoglutarate Aminotransferase In Chlamydomonas Reinhardtii, Zhi Yuan Chen, Mark D. Burow, Catherine B. Mason, James V. Moroney Jan 1996

A Low-Co2-Inducible Gene Encoding An Alanine:Α-Ketoglutarate Aminotransferase In Chlamydomonas Reinhardtii, Zhi Yuan Chen, Mark D. Burow, Catherine B. Mason, James V. Moroney

Faculty Publications

At low-CO2 (air) conditions, the unicellular green alga Chlamydomonas reinhardtii acquires the ability to raise its internal inorganic carbon concentration. To study this adaptation to low CO2, cDNA clones induced under low-CO2 growth conditions were selected through differential screening. One full-length clone is 2552 bp, with an open reading frame encoding 521 amino acids. The deduced amino acid sequence shows about 50% identity with alanine:α-ketoglutarate aminotransferase (Ala AT, EC 2.6.1.2) from plants and animals, and the mRNA of this clone increased 4- to 5-fold 4 h after cells were switched from high-CO2 to low-CO2 growth conditions. The expression of the …

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Metabolism Of Gemmules From The Freshwater Sponge Eunapius Fragilis During Diapause And Post-Diapause States, Stephen H. Loomis, Steven C. Hand, Paul E. Fell Jan 1996

Metabolism Of Gemmules From The Freshwater Sponge Eunapius Fragilis During Diapause And Post-Diapause States, Stephen H. Loomis, Steven C. Hand, Paul E. Fell

Faculty Publications

Post-diapause gemmules of the freshwater sponge Eunapius fragilis remained quiescent when maintained at 5°C. Germination occurred within 48 to 72 h following warming to 20°-23°C, culminating with the emergence of a new sponge from the collagenous capsule. Both heat dissipation and oxygen consumption climbed steadily during germination and eventually reached 600% of the starting values. By comparison, energy flow was much lower over the same period of time in diapausing gemmules, clearly demonstrating metabolic depression during diapause. The calorimetric:respirometric (CR) ratio increased significantly from -354 kJ/mol O2 to -541 kJ/mol O2 between hours 3.5 and 56.5 of germination, with an …

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Effect Of Mutations On The Sensitivity Of Human Beta-Cell Glucokinase To Liver Regulatory Protein, M. Veiga-Da-Cunha, L. Z. Xu, Y. H. Lee, D. Marotta, S. J. Pilkis, E. Van Schaftingen Jan 1996

Effect Of Mutations On The Sensitivity Of Human Beta-Cell Glucokinase To Liver Regulatory Protein, M. Veiga-Da-Cunha, L. Z. Xu, Y. H. Lee, D. Marotta, S. J. Pilkis, E. Van Schaftingen

Faculty Publications

Human beta-cell glucokinase and its liver counterpart displayed a half-saturating concentration of glucose (S0.5) of about 8 mmol/l and a Hill coefficient of 1.7, and were as sensitive to inhibition by the rat liver regulatory protein as the rat liver enzyme. These results indicate that the N-terminal region of glucokinase, which differs among these three enzymes, is not implicated in the recognition of the regulatory protein. They also suggest that the regulatory protein, or a related protein, could modulate the affinity of glucokinase for glucose in beta cells. We have also tested the effect of several mutations, many of which …

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Responses Of Methanotrophic Activity In Soils And Cultures To Water Stress, S. Schnell, G. M. King Jan 1996

Responses Of Methanotrophic Activity In Soils And Cultures To Water Stress, S. Schnell, G. M. King

Faculty Publications

Diffusive gas transport at high water contents and physiological water stress at low water contents limited atmospheric methane consumption rates during experimental manipulations of soil water content and water potential. Maximum rates of atmospheric methane consumption occurred at a soil water content of 25% (grams per gram [dry weight]) and a water potential of about - 0.2 MPa. In contrast, uptake rates were highest at a water content of 38% and a water potential of -0.03 MPa when methane was initially present at 200 ppm. Uptake rates of atmospheric and elevated methane decreased when water potentials were reduced by adding …

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Regulation Of Methane Oxidation In A Freshwater Wetland By Water Table Changes And Anoxia, Peter Roslev, Gary M. King Jan 1996

Regulation Of Methane Oxidation In A Freshwater Wetland By Water Table Changes And Anoxia, Peter Roslev, Gary M. King

Faculty Publications

The effects of water table fluctuations and anoxia on methane emission and methane oxidation were studied in a freshwater marsh. Seasonal aerobic methane oxidation rates varied between 15% and 76% of the potential diffusive methane flux (diffusive flux in the absence of aerobic oxidation). On an annual basis, approximately 43% of the methane diffusing into the oxic zone was oxidized before reaching the atmosphere. The highest methane oxidation was observed when the water table was below the peat surface. This was confirmed in laboratory experiments where short-term decreases in water table levels increased methane oxidation but also net methane emission. …

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Characterization Of The Denaturation And Renaturation Of Human Plasma Vitronectin Ii. Investigation Into The Mechanism Of Formation Of Multimers, Ping Zhuang, Huo Li, Jason G. Williams, Nancy V. Wagner, Dietmar Seiffert, Cynthia B. Peterson Jan 1996

Characterization Of The Denaturation And Renaturation Of Human Plasma Vitronectin Ii. Investigation Into The Mechanism Of Formation Of Multimers, Ping Zhuang, Huo Li, Jason G. Williams, Nancy V. Wagner, Dietmar Seiffert, Cynthia B. Peterson

Faculty Publications

Unfolding and refolding of plasma vitronectin appear irreversible under near physiological conditions, with rearrangements of disulfides and self-association to a multimeric form observed as prominent structural alterations which accompany denaturation. A mechanism for the folding reactions of vitronectin has been proposed (Zhuang, P., Blackburn, M. NPeterson, C. B. (1996) J. Biol. Chem. 270, 14323-14332) in which vitronectin acquires a partially folded intermediate structure which is highly prone to oligomerize into a multimeric form. Strongly oxidizing conditions adopted for refolding from urea were effective at preventing disulfide rearrangement which disrupts distal disulfides near the C terminus of the protein. Prohibiting disulfide …

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Random Amplified Polymorphic Dna Markers In Sweetpotato Infected With Fusarium Lateritium, Frank A. Buffone, Don R. La Bonte, Christopher A. Clark Jan 1996

Random Amplified Polymorphic Dna Markers In Sweetpotato Infected With Fusarium Lateritium, Frank A. Buffone, Don R. La Bonte, Christopher A. Clark

Faculty Publications

DNA isolated from Fusarium lateritium Nees: Fr.-infected 'Jewel' sweetpotato [Ipomoea batatas (L.) Lam.] plants was compared to F. lateritium-free 'Jewel' plants for differences in random amplified polymorphic DNA (RAPD) marker products. Differences in RAPD marker products were detected. Amplified DNA isolations from F. lateritium-infected 'Jewel' plants generated additional, unique DNA fragments not found in amplified DNA isolations of F. lateritium-free 'Jewel' plants. These unique amplified DNA fragments were consistent with those obtained from amplified DNA isolations of the F. lateritium isolate, 91-27-2, used for inoculation. We found that F. lateritium DNA successfully competes with sweetpotato DNA in the polymerase chain …

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Heritability Estimates For Reaction Resistance To Sweetpotato Chlorotic Leaf Distortion Caused By Fusarium Lateritium, Bong Kyoo Kim, Don R. La Bonte, Christopher A. Clark, Mario I. Buteler Jan 1996

Heritability Estimates For Reaction Resistance To Sweetpotato Chlorotic Leaf Distortion Caused By Fusarium Lateritium, Bong Kyoo Kim, Don R. La Bonte, Christopher A. Clark, Mario I. Buteler

Faculty Publications

Narrow-sense heritabilities for reaction to chlorotic leaf distortion (CLD), incited by Fusarium lateritium Nees: Fr., were estimated in sweetpotato [Ipomoea batatas (L.) Lam] by variance component analysis and parent-offspring regression. Visually rated severity reactions to CLD varied greatly among the 20 parents used to generate half-sib progeny from open- pollinated nurseries in 1990 and 1991. Progeny from each nursery were evaluated along with parents in a completely randomized design in two consecutive years. Narrow-sense heritability (h2) estimates based on variance components were moderate on an entry mean basis at 0.61 in 1990, 0.38 in 1991, and 0.33 for the two …

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Nutritional Status In Rural Nigerians [17], R. Cooper, C. Rotimi, J. Kaufman, A. Luke Jan 1996

Nutritional Status In Rural Nigerians [17], R. Cooper, C. Rotimi, J. Kaufman, A. Luke

Faculty Publications

No abstract provided.

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Obesity And Hypertension Prevalence In Populations Of African Origin, Jay S. Kaufman, Ramón A. Durazo-Arvizu, Charles N. Rotimi, Daniel L. Mcgee, Richard S. Cooper Jan 1996

Obesity And Hypertension Prevalence In Populations Of African Origin, Jay S. Kaufman, Ramón A. Durazo-Arvizu, Charles N. Rotimi, Daniel L. Mcgee, Richard S. Cooper

Faculty Publications

Obesity has been shown to be associated with hypertension in Africa, the Caribbean, and the United States, but there has not previously been an opportunity to compare the magnitude of this relation and estimate the contribution of obesity to hypertension risk across these populations. The International Collaborative Study on Hypertension in Blacks (ICSHIB) used age-stratified sampling and a standardized protocol to measure blood pressure and hypertension risk factors. We analyzed data on 9,102 men and women, age 25-74 years, from seven sites. We studied hypertension (140/90 mmHg or medication) in relation to body mass index (BMI) and sex-specific BMI cutpoints …

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Relationship Between Birth Weight And Awake Blood Pressure In Children And Adolescents In Absence Of Intrauterine Growth Retardation, Empar Lurbe, Josep Redon, Vicente Alvarez, Ramon Durazo, Ana Gomez, Jose Tacons, Richard S. Cooper Jan 1996

Relationship Between Birth Weight And Awake Blood Pressure In Children And Adolescents In Absence Of Intrauterine Growth Retardation, Empar Lurbe, Josep Redon, Vicente Alvarez, Ramon Durazo, Ana Gomez, Jose Tacons, Richard S. Cooper

Faculty Publications

This study was designed to examine the relationship between birth weight (BW) and ambulatory blood pressure in children and adolescents, born at term in absence of intrauterine growth retardation. Twenty-four hour ambulatory blood pressure monitoring (ABPM) was performed on 332 children (150 boys), aged from 6 to 16 years. Subjects were stratified by BW tertiles and age. ABPM was performed using SpaceLabs 90207 monitor during a regular school day. Blood pressure (BP) was measured every 20 min from 06:00 to 24:00, and thereafter every 30 min. Means of systolic BP (SBP) and diastolic BP (DBP) during 24 h, daytime (08:00 …

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Gravimetric Method For The Measurement Of Sugar Consumption By Adult Velvetbean Caterpillar (Lepidoptera: Noctuidae), Xikui Wei, Seth J. Johnson Jan 1996

Gravimetric Method For The Measurement Of Sugar Consumption By Adult Velvetbean Caterpillar (Lepidoptera: Noctuidae), Xikui Wei, Seth J. Johnson

Faculty Publications

Determination of food consumption by adult Lepidoptera, especially noctuid species, has not been well studied, possibly because of a lack of appropriate methodology. In order to measure sugar consumption by velvetbean caterpillar, Anticarsia gemmatalis Hubner, a gravimetric method was developed and is presented here together with results obtained using this method. After 24-h exposure to a moth, liquid consumption by the moth was determined by weighing the remaining solution on an electronic balance. The amount of solution consumed was calculated by converting the difference between the weight of the remaining solution and that of the unfed control to a volumetric …

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Beet Armyworm (Lepidoptera: Noctuidae) Control On Cotton In Louisiana, V. J. Mascarenhas, B. R. Leonard, E. Burris, J. B. Graves Jan 1996

Beet Armyworm (Lepidoptera: Noctuidae) Control On Cotton In Louisiana, V. J. Mascarenhas, B. R. Leonard, E. Burris, J. B. Graves

Faculty Publications

Efficacy of selected labeled and experimental insecticides against beet armyworm, Spodoptera exigua (Hubner), populations from Louisiana were determined in both a laboratory diet bioassay and in replicated field plots. Significantly higher LC50'S for chlorpyrifos and thiodicarb were observed for one of two field-collected strains relative to a laboratory-reference strain in the laboratory diet bioassays. No significant differences in susceptibility between the reference strain and field-collected strains were observed for chlorfenapyr (proposed common name), spinosad or tebufenozide. For the reference strain, LC50's (ppm) for tebufenozide, spinosad, chlorfenapyr, chlorpyrifos, and thiodicarb were 2.6, 2.8, 4.8, 4.9, and 319.8, respectively. In two field …

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Strategic Agricultural Trade Policy Interdependence And The Exchange Rate: A Game Theoretic Analysis, P. Lynn Kennedy Jan 1996

Strategic Agricultural Trade Policy Interdependence And The Exchange Rate: A Game Theoretic Analysis, P. Lynn Kennedy

Faculty Publications

Strategic Agricultural Trade Policy Interdependence is modeled using a game theoretic framework. The model distinguishes between the European Community, the United States and a politically passive rest-of-the-world. Particular emphasis is placed on the effect of the exchange rate on the equilibrium outcome of this game. Without compensatory payments to those with the highest political influence, the results suggest that only modest reform is possible. With compensation, liberalization occurs but free trade is not obtained. Simulations also indicate that the U.S. gains incentive to reduce protection given a depreciation of the dollar, while incentive to liberalize trade policies decreases as the …

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Unavoidable Minors Of Large 3-Connected Binary Matroids, Guoli Ding, Bogdan Oporowski, James Oxley, Dirk Vertigan Jan 1996

Unavoidable Minors Of Large 3-Connected Binary Matroids, Guoli Ding, Bogdan Oporowski, James Oxley, Dirk Vertigan

Faculty Publications

We show that, for every integer n greater than two, there is a number N such that every 3-connected binary matroid with at least N elements has a minor that is isomorphic to the cycle matroid of K3,n, its dual, the cycle matroid of the wheel with n spokes, or the vector matroid of the binary matrix (In|Jn-In), where Jn is the n × n matrix of all ones. © 1996 Academic Press, Inc.

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Excluding A Long Double Path Minor, Guoli Ding Jan 1996

Excluding A Long Double Path Minor, Guoli Ding

Faculty Publications

The "height" of a graph G is defined to be the number of steps to construct G by two simple graph operations. Let Bn be the graph obtained from an n-edge path by doubling each edge in parallel. Then, for any minor-closed class script G of graphs, the following are proved to be equivalent: (1) Some Bn is not in script G; (2) There is a number h such that every graph in script G has height at most h; (3) script G is well-quasi-ordered by the topological minor relation; (4) There is a polynomial function p( • ) such …

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An Anticipatory Itô Formula, Hui Hsiung Kuo, Kenjiro Nishi Jan 1996

An Anticipatory Itô Formula, Hui Hsiung Kuo, Kenjiro Nishi

Faculty Publications

No abstract provided.

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Composites With Imperfect Interface, Robert Lipton, Bog D.An Vernescu Jan 1996

Composites With Imperfect Interface, Robert Lipton, Bog D.An Vernescu

Faculty Publications

New variational principles and bounds are introduced, describing the effective conductivity tensor for anisotropic two-phase heat conducting composites with interfacial surface resistance between phases. The new upper bound is given in terms of the two-point correlation function, component volume fractions and moment of inertia tensor for the surface of each heterogeneity. The new lower bound is given in terms of the interfacial surface area, component volume fractions and a scale-free matrix of parameters. This matrix corresponds to the effective conductivity associated with the same geometry but with non-conducting inclusions. The bounds are applied to theoretically predict the occurrence of size …

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On Inequivalent Representations Of Matroids Over Finite Fields, James Oxley, Dirk Vertigan, Geoff Whittle Jan 1996

On Inequivalent Representations Of Matroids Over Finite Fields, James Oxley, Dirk Vertigan, Geoff Whittle

Faculty Publications

Kahn conjectured in 1988 that, for each prime power q, there is an integer n(q) such that no 3-connected GF(q)-representable matroid has more than n(q) inequivalent GF(q)-representations. At the time, this conjecture was known to be true for q = 2 and q = 3, and Kahn had just proved it for q = 4. In this paper, we prove the conjecture for q = 5, showing that 6 is a sharp value for n(5). Moreover, we also show that the conjecture is false for all larger values of q. © 1996 Academic Press, Inc.

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Extension Sets For Real Analytic Functions And Applications To Radon Transforms, Vernor Arguedas, Ricardo Estrada Jan 1996

Extension Sets For Real Analytic Functions And Applications To Radon Transforms, Vernor Arguedas, Ricardo Estrada

Faculty Publications

The real analytic character of a function f(x,y) is determined from its behavior along radial directions fθ(s) = f(s cos θ, s sin θ) for θ ∈ E, where Ε is a "small" set A support theorem for Radon transforms in the plane is proved In particular if fθ extends to an entire function for θ ∈ Ε and ƒ (x, y) is real analytic in R2 then it also extends to an entire function in C2. © 1996, Hindawi Publishing Corporation. All rights reserved.

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Multigrid Methods For Parameter Dependent Problems, Susanne C. Brenner Jan 1996

Multigrid Methods For Parameter Dependent Problems, Susanne C. Brenner

Faculty Publications

Multigrid methods for parameter dependent problems are discussed. The contraction numbers of the algorithms are proved within a unifying framework to be bounded away from one, independent of the parameter and the mesth levels. Examples include the pure displacement and pure traction boundary value problems in planar linear elasticity, the Timoshenko beam problem, and the Reissner-Mindlin plate problem.

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Rigorous Solution Of The Quantum Einstein Equations, Rodolfo Gambini, Jorge Pullin Jan 1996

Rigorous Solution Of The Quantum Einstein Equations, Rodolfo Gambini, Jorge Pullin

Faculty Publications

We show that the second coefficient of the Conway knot polynomial is annihilated by the Hamiltonian constraint of canonically quantized general relativity in the loop representation. The calculations are carried out in a fully regularized lattice framework. Crucial to the calculation is the explicit form of the skein relations of the second coefficient, which relate it to the Gauss linking number. Contrary to the lengthy formal continuum calculation, the rigorous lattice version can be summarized in a few pictures. © 1996 The American Physical Society.

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Analytic Approximations To The Spacetime Of A Critical Gravitational Collapse, Richard H. Price, Jorge Pullin Jan 1996

Analytic Approximations To The Spacetime Of A Critical Gravitational Collapse, Richard H. Price, Jorge Pullin

Faculty Publications

We present analytic expressions that approximate the behavior of the spacetime of a collapsing spherically symmetric scalar field in the critical regime first discovered by Choptuik. We find that the critical region of spacetime can usefully be divided into a "quiescent," an "oscillatory," and a moving "transition" region. We find that in the quiescent and oscillatory regions the critical solution can be well approximated by a flat spacetime scalar field solution. A qualitative nonlinear matching of the solutions across the transition region yields the right order of magnitude for the oscillations of the discretely self-similar critical solution found by Choptuik. …

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