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Iowa State University

1994

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Critical Dynamics Of Nonconserved Ising-Like Systems, K. E. Bassler, Beate Schmittmann Dec 1994

Critical Dynamics Of Nonconserved Ising-Like Systems, K. E. Bassler, Beate Schmittmann

Beate Schmittmann

We show that the dynamical fixed point of Ising-like models, characterized by a single scalar, nonconserved ordering field, is stable near four dimensions with respect to all dynamic perturbations, including those of a nonequilibrium nature.


Non-Opsonic Attachment Of Bordetella Bronchiseptica Mediated By Cd11/Cd18 And Cell Surface Carbohydrates, Karen B. Register, Mark R. Ackermann, Marcus E. Kehrli Jr. Dec 1994

Non-Opsonic Attachment Of Bordetella Bronchiseptica Mediated By Cd11/Cd18 And Cell Surface Carbohydrates, Karen B. Register, Mark R. Ackermann, Marcus E. Kehrli Jr.

Mark R. Ackermann

Porcine atrophic rhinitis associated with Bordetella bronchiseptica is characterized by a severe inflammatory response in the mucosa of the nasal turbinates. Initial infiltrates of polymorphonuclear leukocytes (PMN) are followed by accumulations of mononuclear cells. In this report, we have investigated the interaction between porcine PMN and B. bronchiseptica. PMN incubated in PBS with a fluorescently labeled hemagglutinating porcine isolate, but not a non-hemagglutinating variant, had high levels of cell-associated fluorescence as determined by flow cytometry. Light microscopy indicated that most cell-associated bacteria were ingested. Transmission electron microscopy confirmed the presence of intracellular bacteria, which were contained within membrane-bound phagosomes. A …


Low‐Temperature Phase Diagram Of Ybbipt, R. Movshovich, A. Lacerda, Paul C. Canfield, J. D. Thompson, Z. Fisk Nov 1994

Low‐Temperature Phase Diagram Of Ybbipt, R. Movshovich, A. Lacerda, Paul C. Canfield, J. D. Thompson, Z. Fisk

Paul C. Canfield

Resistivity measurements are reported on the cubic heavy‐fermion compound YbBiPt at ambient and hydrostatic pressures to ≊19 kbar and in magnetic fields to 1 T. The phase transition at T c =0.4 K is identified by a sharp rise in resistivity. That feature is used to build low‐temperature H‐T and P‐Tphase diagrams. The phase boundary in the H‐T plane follows the weak‐coupling BCS expression remarkably well from T c to T c /4, while small hydrostatic pressure of ≊1 kbar suppresses the low‐temperature phase entirely. These effects of hydrostatic pressure and magnetic field on the phase transition are consistent with …


Using Biodiversity Data To Assess Species--Habitat Relationships In Glacier National Park, Montana, Diane M. Debinski, Peter F. Brussard Nov 1994

Using Biodiversity Data To Assess Species--Habitat Relationships In Glacier National Park, Montana, Diane M. Debinski, Peter F. Brussard

Diane M. Debinski

Biodiversity surveys are becoming increasingly popular. However, standard analysis techniques for these data have not yet been developed. This paper explores the use of multivariate ordination techniques for assessing species—habitat relationships using biodiversity data. The research was conducted in Glacier National Park, Montana, and birds and butterflies were chosen as the taxonomic groups of study. Biodiversity assessment sites were established throughout a range of habitats and monitored from 1987 through 1989. Presence/absence sampling over the total number of sampling sites was used to classify species commonness and rarity. Approximately 86% of the historically recorded butterflies and 70% of the historically …


Spontaneous Structure Formation In Driven Systems With Two Species: Exact Solutions In A Mean-Field Theory, I. Vilfan, R. K. P. Zia, Beate Schmittmann Oct 1994

Spontaneous Structure Formation In Driven Systems With Two Species: Exact Solutions In A Mean-Field Theory, I. Vilfan, R. K. P. Zia, Beate Schmittmann

Beate Schmittmann

A stochastic lattice gas of particles, subject to an excluded volume constraint and to a uniform external driving field, is investigated. Using a mean-field theory for a system with equal number of oppositely charged particles, exact results are obtained. Focusing on the current-vs-density plot, we propose an explanation for the discontinuous transition found in earlier simulations. A critical value of the drive, below which this transition becomes continuous, is found. These results are supported by a bifurcation analysis, leading to an equation of motion for the amplitude of the soft mode.


How Synchronous Are Neogene Marine Plankton Events?, Cinzia Spencer-Cervato, Hans R. Thierstein, David B. Lazarus, Jean-Pierre Beckmann Oct 1994

How Synchronous Are Neogene Marine Plankton Events?, Cinzia Spencer-Cervato, Hans R. Thierstein, David B. Lazarus, Jean-Pierre Beckmann

Cinzia Cervato

An electronic supplement of this material may be obtained on adiskette or Anonymous FTP from KOSMOS.AGU.ORG. (LOGIN toAGU's FTP account using ANONYMOUS as the username andGUEST as the password. Go to the right directory by typing CDAPEND. Type LS to see what files are available. Type GET and thename of the file to get it. Finally, type EXIT to leave the system.)(Paper 94PA01456, How synchronous are Neogene marine planktonevents?, by C. Spencer-Cervato, H. R. Thierstein, D. B. Lazarus, andJ-P Beckmann). Diskette may be ordered from American GeophysicalUnion, 2000 Florida Avenue, N.W., Washington, DC 20009; $15.00.Payment must accompany order. We analyzed …


Pulmonary Lesions In Fetuses Exposed In Utero To Porcine Reproductive And Respiratory Syndrome Virus, Kelly M. Lager, Mark R. Ackermann Oct 1994

Pulmonary Lesions In Fetuses Exposed In Utero To Porcine Reproductive And Respiratory Syndrome Virus, Kelly M. Lager, Mark R. Ackermann

Mark R. Ackermann

The salient features of a porcine reproductive and respiratory syndrome (PRRS) epizootic include respiratory disease followed by reproductive failure. The respiratory component is usually recognized first in finishing pigs or in the breeding herd as a mild flu-like disease with a high morbidity for all ages and high mortality in younger pigs. In breeding herds, acute maternal reproductive failure often follows the onset of respiratory disease. PRRS is characterized by a sudden increase in early farrowings, late-term abortions, stillborn and mummified fetuses, weak neonates with high mortality, late returns to estrus, and repeat breeders. No consistent histopathology has been obseived …


Impact Of Human Visual Perception Of Color On Very Low Bit-Rate Image Coding, Sarah A. Rajala Sep 1994

Impact Of Human Visual Perception Of Color On Very Low Bit-Rate Image Coding, Sarah A. Rajala

Sarah A. Rajala

One of the keys to obtaining acceptable quality imagery/video encoded at very low bit rates is to transmit only that information which is critical to human perception. To successfully achieve this goal, one must not only understand the human visual system, but be able to utilize this information in the design of their codec. This paper will present an overview of the properties associated with color science and human visual perception, and how they could make an impact on very low bit-rate image coding.


Participation Of The Β Phosphonate Group In Carbocation Formation, Joseph B. Lambert, Robert W. Embridge, Yan Zhao Sep 1994

Participation Of The Β Phosphonate Group In Carbocation Formation, Joseph B. Lambert, Robert W. Embridge, Yan Zhao

Yan Zhao

Diethyl (2-(tosyloxy)cyclohexyl)phosphonates have been prepared to test the hypothesis that the strongly electron-withdrawing phosphonate group can stabilize the formation of a /3 carbocation through hyperconjugation. Systems were constructed with the 180" dihedral angle between phosphonate and tosyloxy that is optimal for such participation and with the 60" dihedral angle that minimizes it. Reactions were carried out in aqueous mixtures of ethanol, trifluoroethanol, and hexafluoro-2-propanol. The 60" case had the standard profile for bimolecular reaction with solvent (kB),w ith a slower rate that is sensitive to solvent nucleophilicity. The 180" case had the standard profile for a carbocation pathway (kc), with …


Compositional Short-Range Ordering In Metallic Alloys: Band-Filling, Charge-Transfer, And Size Effects From A First-Principles All-Electron Landau-Type Theory, J. B. Staunton, Duane D. Johnson, F. J. Pinski Jul 1994

Compositional Short-Range Ordering In Metallic Alloys: Band-Filling, Charge-Transfer, And Size Effects From A First-Principles All-Electron Landau-Type Theory, J. B. Staunton, Duane D. Johnson, F. J. Pinski

Duane D. Johnson

Using a mean-field statistical description, we derive a general formalism to investigate atomic short-range order in alloys based on a density-functional description of the finite-temperature, grand potential of the random alloy. This ‘‘first-principles,’’ Landau-type approach attempts to treat several contributions (electronic structure, Fermi surface, electrostatics, magnetism, etc.) to the electronic energy on an equal footing. An important ingredient for the statistical averaging is the replacement of the molecular mean fields (Weiss fields) with Onsager cavity fields, which forces the diagonal part of the fluctuation-dissipation theorem to be obeyed. To show its general applicability and usefulness, we apply the theory to …


First-Principles All-Electron Theory Of Atomic Short-Range Ordering In Metallic Alloys: D022- Versus L12-Like Correlations, Duane D. Johnson, J. B. Staunton, F. J. Pinski Jul 1994

First-Principles All-Electron Theory Of Atomic Short-Range Ordering In Metallic Alloys: D022- Versus L12-Like Correlations, Duane D. Johnson, J. B. Staunton, F. J. Pinski

Duane D. Johnson

We use a ‘‘first-principles’’ concentration-wave approach based on a finite-temperature, electronic density-functional, mean-field, grand potential of the random alloy to investigate the high-temperature atomic short-range order (ASRO) in Ni75V25 and Pd75V25 solid solutions. Experimentally, these similar alloys both develop D022-type long-range order at low temperatures but different ASRO at high temperatures. Our calculations describe the measured ASRO well. We compare these results with those found for a hypothetical Co75Ti25 solid solution. Since this alloy orders directly from the melt into the L12 phase, it should exhibit strong L12-like ASRO, as we find in our calculations. We analyze the features in …


Surface-Induced Ordering In Asymmetric Block Copolymers, Y. Liu, W. Zhao, X. Zheng, Alexander H. King, A. Sing, M. H. Rafailovich, J. Sokolov, K. H. Dai, E. J. Kramer, S. A. Schwarz, O. Gebizlioglu, S. K. Sinha Jul 1994

Surface-Induced Ordering In Asymmetric Block Copolymers, Y. Liu, W. Zhao, X. Zheng, Alexander H. King, A. Sing, M. H. Rafailovich, J. Sokolov, K. H. Dai, E. J. Kramer, S. A. Schwarz, O. Gebizlioglu, S. K. Sinha

Alexander H. King

The surface-induced ordering in thin films of asymmetric deuterated polystyrene (dPS)- poly(viny1pyridine) (PVP) diblock and triblock copolymers of comparable polymerization index and PVP volume fraction - 0.25) was studied using transmission electron microscopy, atomic force microscopy, secondary ion massspectrometry, and neutron reflectivity. The morphology of both di- and triblock copolymer films was found to be cylindrical except for the layer adjacent to the silicon oxide surface, which due to the strong interaction of silica with PVP, was lamellar. The spacing between adjacent cylindrical layers was found to be consistent with mean field theory predictions. In the triblock copolymer films the …


A Nuclear Juvenile Hormone-Binding Protein From Larvae Of Manduca Sexta: A Putative Receptor For The Metamorphic Action Of Juvenile Hormone, Subba R. Palli, Kazushige Touhara, Jean-Philippe Charles, Bryony C. Bonning, Jeffrey K. Atkinson, Stephen C. Trowell, Kiyoshi Hiruma, Walter G. Goodman, Themis Kyriakides, Glenn D. Prestwich, Bruce D. Hammock, Lynn M. Ridiford Jun 1994

A Nuclear Juvenile Hormone-Binding Protein From Larvae Of Manduca Sexta: A Putative Receptor For The Metamorphic Action Of Juvenile Hormone, Subba R. Palli, Kazushige Touhara, Jean-Philippe Charles, Bryony C. Bonning, Jeffrey K. Atkinson, Stephen C. Trowell, Kiyoshi Hiruma, Walter G. Goodman, Themis Kyriakides, Glenn D. Prestwich, Bruce D. Hammock, Lynn M. Ridiford

Bryony C. Bonning

A 29-kDa nuclear juvenile hormone (JH)-binding protein from the epidermis of Manduca sexta larvae was purified by using the photoaffinity analog for JH II ([3H]epoxyhomofarnesyldiazoacetate) and partially sequenced. A 1.1-kb cDNA was isolated by using degenerate oligonucleotide primers for PCR based on these sequences. The cDNA encoded a 262-amino acid protein that showed no similarity with other known proteins, except for short stretches of the interphotoreceptor retinoid-binding protein, rhodopsin, and human nuclear protein p68. Recombinant baculovirus containing this cDNA made a 29-kDa protein that was covalently modified by [3H]epoxyhomofarnesyldiazoacetate and specifically bound the natural enantiomer of JH I (Kd = …


Reducing Respiratory Artifacts In Chest Mr Images Through Hybrid Space Motion Tracking And Postprocessing, John N. Campbell, Wesley E. Snyder, Peter Santago Ii, Sarah A. Rajala, Craig A. Hamilton May 1994

Reducing Respiratory Artifacts In Chest Mr Images Through Hybrid Space Motion Tracking And Postprocessing, John N. Campbell, Wesley E. Snyder, Peter Santago Ii, Sarah A. Rajala, Craig A. Hamilton

Sarah A. Rajala

A new postprocessing method of correcting for respiratory motion induced artifacts in MRI is presented. The motion of the chest during respiration is modeled as a combination of translation and dilation. Displacements of the chest wall are tracked via a thin, MR-sensitive plate placed on the patient's chest during a scan. Scanning with phase encoding left/right (L/R) and frequency encoding anterior/posterior (A/P) causes the motion artifacts to be repeated in the L/R direction, thus not overlapping on the plate. By performing the inverse A/P Fourier transform, the resulting hybrid space data has A/P spatial data and L/R spatial frequency data, …


The Phosphate Transporter From Pea Mitochondria (Isolation And Characterization In Proteolipid Vesicles), Cecilia A. Mcintosh, David J. Oliver May 1994

The Phosphate Transporter From Pea Mitochondria (Isolation And Characterization In Proteolipid Vesicles), Cecilia A. Mcintosh, David J. Oliver

David J. Oliver

The phosphate transporter from mitochondria will exchange matrix phosphate for cytosolic phosphate and facilitate either phosphate/proton symport or phosphate/hydroxyl ion antiport. The phosphate transported into the matrix by this carrier is either used for ATP synthesis or exchanges back out to the cytosol on the dicarboxylate transporter, permitting entry of malate and succinate into the matrix. The phosphate transporter was solubilized from etiolated pea (Pisum sativum L. cv Alaska) mitochondrial membranes with Triton X-114, purified approximately 500-fold by hydroxylapatite chromatography, and reconstituted into azolectin vesicles that were preloaded with 0.1 or 10 mM phosphate. Phosphate transport was measured as the …


Renormalization-Group Study Of A Hybrid Driven Diffusive System, K. E. Bassler, Beate Schmittmann May 1994

Renormalization-Group Study Of A Hybrid Driven Diffusive System, K. E. Bassler, Beate Schmittmann

Beate Schmittmann

We consider a d-dimensional stochastic lattice gas of interacting particles, diffusing under the influence of a short-ranged, attractive Ising Hamiltonian and a ‘‘hybrid’’ external field which is a superposition of a uniform and an annealed random drive, acting in orthogonal subspaces of dimensions one and m, respectively. Driven into a nonequilibrium steady state, the half-filled system phase segregates via a continuous transition at a field-dependent critical temperature. Using renormalization-group techniques, we show that its critical behavior falls into a new universality class with upper critical dimension dc=5-m, characterized by two distinct anisotropy exponents, which, like all other indices, are computed …


Distribution Of Anti-Cd68 (Ebm11) Immunoreactivity In Formalin-Fixed, Paraffin-Embedded Bovine Tissues, Mark R. Ackermann, B. M. Debey, T. J. Stabel, J. H. Gold, K. B. Register, J. T. Meehan May 1994

Distribution Of Anti-Cd68 (Ebm11) Immunoreactivity In Formalin-Fixed, Paraffin-Embedded Bovine Tissues, Mark R. Ackermann, B. M. Debey, T. J. Stabel, J. H. Gold, K. B. Register, J. T. Meehan

Mark R. Ackermann

A commercially acquired anti-human macrophage antibody (anti-CD68; EBM11) was used in an immunocytochemical technique to detect macrophages in formalin-fixed, paraffin-embedded tissues from cattle, pigs, humans, rats, turkeys, dogs, and cats. In healthy cattle, the antibody labeled alveolar macrophages, pulmonary intravascular cells (presumably intravascular macrophages), and macrophage-like cells in other tissues. In bovine lungs infected with Pasteurella haemolytica, EBM11 antibody labeled 95% of alveolar macrophages and macrophages within alveolar septa but only 0–2% of streaming or “oat” leukocytes. Alveolar macrophages were also stained by EBM11 in pigs but not in rats, turkeys, dogs, and cats. The antibody also stained macrophage aggregates …


Use Of Extrapolation In Computing Color Look-Up Tables, Sarah A. Rajala, H. Joel Trussell, Atish P. Kakodkar Apr 1994

Use Of Extrapolation In Computing Color Look-Up Tables, Sarah A. Rajala, H. Joel Trussell, Atish P. Kakodkar

Sarah A. Rajala

Colorimetric reproduction requires calibrated color output devices. One way to characterize a color output device is with a 3D look-up table which maps the tristimulus values, t, to the control values, c of the output device. The functional form of the output device can be written in vector notation as t equals F(c). The purpose of calibration is to define an inverse mapping from tristimulus values to control values. Since the function F((DOT)) has no closed form, it is defined by interpolation from a table of values. Given a set of control values ]ci[ on a regular grid and the …


Aspects Of Vernacular Architecture In Postpalatial And Early Iron Age Crete, Margaret S. Mook, Donald C. Haggis Apr 1994

Aspects Of Vernacular Architecture In Postpalatial And Early Iron Age Crete, Margaret S. Mook, Donald C. Haggis

Margaret S. Mook

Vernacular architecture in Postpalatial Crete exhibits a distinct diversion from the domestic architectural traditions of the Neopalatial period. In Neopalatial Crete, house designs are frequently dependent on Minoan palatial models and all house styles have a complexity that is seldom seen in the ensuing periods. Changes in vernacular architectural plans have emerged by the beginning of Late Minoan III, and include single-room dwellings and axially planned twoor three-room houses; they are found island-wide and continue and develop through the Early Iron Age. Standard features of these architectural types are defined and documented from LM III through the Late Geometric period, …


Phenotypic Expression Of Recombinant Plasmids Pkt107 And Phk11 In An Avirulent Avian Escherichia Coli, Richard E. Wooley, Lisa K. Nolan, John Brown, Penelope S. Gibbs, Denise I. Bounous Mar 1994

Phenotypic Expression Of Recombinant Plasmids Pkt107 And Phk11 In An Avirulent Avian Escherichia Coli, Richard E. Wooley, Lisa K. Nolan, John Brown, Penelope S. Gibbs, Denise I. Bounous

Lisa K. Nolan

An avirulent wild-type avian Escherichia coli strain (Av) was electrotransformed with plasmids coding for complement resistance (pKT107) and Colicin V (ColV) production (pHK11) in order to study the effects of complement resistance and ColV production on virulence. Transformants were also compared with the wild type for embryo lethality, uptake by macrophages, motility, growth rate, plasmid content, and hemolysis. Growth rates and complement resistance patterns of strain Av and transformant Av+pHK1 1 were similar, but Av+pHK11 caused a significantly greater number of deaths in embryos and acquired motility. Transformant Av+pKT107 had a lower rate of phagocytosis, a slower growth rate, and …


Characterization Of An Avirulent Mutant Of A Virulent Avian Escherichia Coli Isolate, Lisa K. Nolan, Richard E. Wooley, Catherine W. Giddings, John Brown Mar 1994

Characterization Of An Avirulent Mutant Of A Virulent Avian Escherichia Coli Isolate, Lisa K. Nolan, Richard E. Wooley, Catherine W. Giddings, John Brown

Lisa K. Nolan

A virulent, complement-resistant avian Escherichia co/lisolate and its avirulent, complement-sensitive, transposon-insertion mutant were compared for the purpose of revealing structures associated with complement resistance. Both had a smooth lipopolysaccharide layer, contained traT, and lacked a capsule, but the mutant possessed a 16.2-kilodalton outer-membrane protein (OMP) not present in the wild-type. This protein may be the product of a coding region interrupted by transposon insertion. Such results suggest that an OMP greater than 16.2 kilodaltons in size may be responsible for the complement resistance and virulence of this wild-type E. coli.


Infected Cell Types In Ovine Lung Following Exposure To Bovine Respiratory Syncytial Virus, J. T. Meehan, R. C. Cutlip, H. D. Lehmkuhl, J. P. Kluge, Mark R. Ackermann Mar 1994

Infected Cell Types In Ovine Lung Following Exposure To Bovine Respiratory Syncytial Virus, J. T. Meehan, R. C. Cutlip, H. D. Lehmkuhl, J. P. Kluge, Mark R. Ackermann

Mark R. Ackermann

Sixteen adult sheep (ten females, six males obtained from a closed flock at National Animal Disease Center, Ames, IA) were experimentally infected with bovine respiratory syncytial virus strain 375 (BRSV), and lung tissues were stained for viral antigen. Two infected sheep were euthanatized at each of the following post-inoculation times: 12, 24, 36, 48, 72, 96, 144, and 192 hours. Lung, nasal turbinates, trachea, right cranial bronchial and mediastinal lymph nodes, liver, and spleen were collected for histologic evaluation. An indirect immunoperoxidase technique was performed on routine paraffin-embedded sections of lung tissue, trachea, turbinates, and bronchial and mediastinal lymph nodes …


Effect Of Normal Intestinal Flora Of Chickens On Colonization By Virulent Colicin V-Producing, Avirulent, And Mutant Colicin V-Producing Avian Escherichia Coli, Richard E. Wooley, John Brown, Penelope S. Gibbs, Lisa K. Nolan, Kathy R. Turner Mar 1994

Effect Of Normal Intestinal Flora Of Chickens On Colonization By Virulent Colicin V-Producing, Avirulent, And Mutant Colicin V-Producing Avian Escherichia Coli, Richard E. Wooley, John Brown, Penelope S. Gibbs, Lisa K. Nolan, Kathy R. Turner

Lisa K. Nolan

Colonization of the intestinal tracts of newly hatched chicks with Escherichia coli was attempted by swabbing test organisms onto the air-shell of 19-day-old embryos. Test organisms consisted of two virulent E. coli isolates, one avirulent isolate, and one laboratory-derived mutant of the avirulent isolate carrying a recombinant plasmid coding for Colicin V production. Chicks were cultured weekly for 3 weeks for total E. coliand for the test organisms using selective media. Control chicks were sampled on weeks 1 and 5, and the normal E. coli intestinal microflora were examined for the production of colicins. The two virulent E. coli isolates …


Minorities In Hospitality Management, Robert H. Bosselman Jan 1994

Minorities In Hospitality Management, Robert H. Bosselman

Robert H. Bosselman

Although diversity in hospitality management benefits from business open-door policies and managerial development programs, it will be necessary for educational programs to go well beyond their traditional recruitment and retention programs to help minorities pursue opportunities in the hospitality field. This article reviews minority participation in the field and proposes some strategies for success.


Insect Control By Use Of Recombinant Baculoviruses Expressing Juvenile Hormone Esterase, Bryony C. Bonning, Bruce D. Hammock Jan 1994

Insect Control By Use Of Recombinant Baculoviruses Expressing Juvenile Hormone Esterase, Bryony C. Bonning, Bruce D. Hammock

Bryony C. Bonning

Anti-juvenile hormone activity, and the resulting cessation of feeding, has long been considered by the agricultural chemical industry as a means for insect control. Juvenile hormone esterase (JHE) contributes to the decline in JH titer at certain times during larval development. This chapter reviews the efforts made to develop a fast acting recombinant baculovirus insecticide by creating a virus which will express artificially high levels of JHE in the insect at inappropriate times. The findings are discussed in the light of our current understanding of the regulation of larval development and the role of JHE. Prospects for the newly developed, …


Predicting Modes Of Toxic Action From Chemical Structure: An Overview, Steven P. Bradbury Jan 1994

Predicting Modes Of Toxic Action From Chemical Structure: An Overview, Steven P. Bradbury

Steven P. Bradbury

In the field of environmental toxicology, and especially aquatic toxicology, quantitative structure activity relationships (QSARs) have developed as scientifically-credible tools for predicting the toxicity of chemicals when little or no empirical data are available. A basic and fundamental understanding of toxicological principles has been considered crucial to the continued acceptance and application of these techniques as biologically relevant. As a consequence, there has been an evolution of QSAR development and application from that of a chemical-class perspective to one that is more consistent with assumptions regarding modes of toxic action. The assessment of a compound’s likely mode of toxic action …


Improved Fokker–Planck Model For The Joint Scalar, Scalar Gradient Pdf, Rodney O. Fox Jan 1994

Improved Fokker–Planck Model For The Joint Scalar, Scalar Gradient Pdf, Rodney O. Fox

Rodney O. Fox

The joint scalar, scalar gradient probability density function (PDF) of an inert nonpremixed scalar diffusing in a one-dimensional system of random-sized lamellas is investigated by numerical simulation. The form of the scalar PDF, at a given RMS value, is nearly identical to that predicted by direct numerical simulation (DNS) of scalar mixing in isotropic turbulence and the mapping closure, and the moments of both the scalar and the scalar gradient suggest that their limiting marginal PDF are Gaussian. The joint scalar, scalar gradient PDF is found to be restricted to a bounded region in the scalar-scalar gradient plane, whose form …


Influence Of Summer Storms On The Solution Geochemistry In A Coastal Plain Hydrosequence, Jeffrey M. Novak, C. Lee Burras Jan 1994

Influence Of Summer Storms On The Solution Geochemistry In A Coastal Plain Hydrosequence, Jeffrey M. Novak, C. Lee Burras

C. Lee Burras

An understanding of factors which influence wetland soil solution chemistry is important for soil solutions are known to influence some chemical properties of surface waters. The influence of summer storms on the solution geochemistry in a South Carolina riverine wetland soil was evaluated by comparing pore water collected 2,4 hr after five summer storm events with pore water acquired during five nonstorm periods. Pore water was collected by tension lysimeters buried at 15 to 152 cm in two locations along a hydrologic gradient. Samples of rain, throughfall and stream water were also collected. Overall, summer storms had no significant influence …


Induced Lsoflavonoids In Diverse Populations Of Astragalus Cicer, Andrew W. Lenssen, Susan S. Martin, Charley E. Townsend Jan 1994

Induced Lsoflavonoids In Diverse Populations Of Astragalus Cicer, Andrew W. Lenssen, Susan S. Martin, Charley E. Townsend

Andrew W. Lenssen

lsoflavonoids were induced in mature leaves of the legume Asbagalus cicer L. by spores of the fungus Bipoaris zeicola. The five major elicited compounds included two isoflavans (mucronulatol and astraciceran), two isoflavones (cajanin and acicerone), and a pterocarpan (maackiain). Only occasional traces of these compounds were detected in controls. Among 41 populations originating in Europe or Russia, mean total elicited isoflavonoid content differed 12-fold. Mucronulatol was the predominant compound elicited, comprising 20-70% of total isoflavonoids. Significant interpopulational differences existed for each isoflavonoid, but no geographic patterns of total or relative proportions of the five compounds were discernible.


Acicerone: An Isoflavone From Astragalus Cicer, Andrew W. Lenssen, Susan S. Martin, Charley E. Townsend, Bruce Hawkins Jan 1994

Acicerone: An Isoflavone From Astragalus Cicer, Andrew W. Lenssen, Susan S. Martin, Charley E. Townsend, Bruce Hawkins

Andrew W. Lenssen

A new isoflavone isolated from fungus-inoculated roots of Astragalus cicer has been identified as 6-hydroxy- 7-methoxy-3’,4’-methylenedioxyisoflavone (acicerone).