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Articles 1 - 26 of 26
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Diet-Selection Ecology Of Tropically And Temperately Adapted Honey Bees, Robert G. Danka, Richard L. Hellmich, Thomas E. Rinderer, Anita M. Collins
Diet-Selection Ecology Of Tropically And Temperately Adapted Honey Bees, Robert G. Danka, Richard L. Hellmich, Thomas E. Rinderer, Anita M. Collins
Richard L Hellmich
Colonies of tropically adapted (Africanized) honey bees had greater numbers and higher percentages of pollen foragers than did temperately adapted (European) honey bees. European colonies had greater overall foraging activity. The number of pollen gatherers in Africanized nests was greater throughout the daily foraging cycle, and was especially high early in the morning when pollen was most abundant. Africanized colonies fielded more pollen collectors even when levels of stimuli which are known to regulate pollen foraging were altered experimentally. Collectively, the foraging patterns resulted in larger stores of pollen in Africanized honey bee nests, while European bee nests typically had …
On The Liquid Flow Distribution In Trickle-Bed Reactors, Rodney O. Fox
On The Liquid Flow Distribution In Trickle-Bed Reactors, Rodney O. Fox
Rodney O. Fox
The previous analytical expression for the liquid flow distribution in trickle beds found by maximizing the so-called configurational entropy is reviewed, and a novel derivation is offered, more closely modeling data found in the literature. The novel distribution is an analytical expression describing the liquid flow distribution recently found by employing a Monte Carlo simulation of the very large lattice model (VLLM), thus reducing this computationally time-consuming procedure to a simple equation. The resultant distribution is a function of the total flow rate through the trickle bed, the bed permeability as expressed by the number of open channels through the …
Theoretical Study Of The Environmental Effects On The Hyperfine Fields Of Ni And Fe In Ni0.75fe0.25, H. Ebert, H. Winter, B. Gyorffy, Duane D. Johnson, F. J. Pinski
Theoretical Study Of The Environmental Effects On The Hyperfine Fields Of Ni And Fe In Ni0.75fe0.25, H. Ebert, H. Winter, B. Gyorffy, Duane D. Johnson, F. J. Pinski
Duane D. Johnson
The dependence of the hyperfine fields Bhf of Ni and Fe in Ni0.75Fe0.25 on the surrounding atomic configuration has been studied by performing charge selfconsistent 6 shell-cluster Korringa-Kohn-Rostoker Coherent Potential Approximation (KKR-CPA) bandstructure calculations. By replacing the CPA- scatterers in the various shells around the central atom by Ni - or Fe-atoms, respectively, it could be shown that the hyperfine fields vary linearly with the number of Fe-atoms within a given shell and that the changes of Bhf due to simultaneous changes of the atomic configurations of different shells are additive. The changes of the hyperfine fields upon ordering of …
Prey Depletion By Odonate Larvae: Combining Evidence From Multiple Field Experiments, Clay L. Pierce, Dan M. Johnson, Thomas H. Martin, Charles N. Watson, Robert E. Bohanan, Philip H. Crowley
Prey Depletion By Odonate Larvae: Combining Evidence From Multiple Field Experiments, Clay L. Pierce, Dan M. Johnson, Thomas H. Martin, Charles N. Watson, Robert E. Bohanan, Philip H. Crowley
Clay L. Pierce
In this paper we re-analyze previously published data regarding the response of several prey populations to manipulation of predaceous larval dragonfly (Insecta: Odonata) densities in four separate field enclosure experiments. Using a computer-intensive "rerandomization" approach to testing hypotheses, we show that the individual experiments were not sufficiently powerful to consistently reject false null hypotheses. Combining the data from three comparable experiments, we can enhance the power associated with such tests. Three prey categories (Trichoptera, Oligochaeta, and large Cladocera), constituting less than one-third of the typical odonate diet, were found to be consistently depleted in enclosures with odonate larvae; but the …
Molecular And Electronic Structure Of Si3h6, Mark S. Gordon, David Bartol
Molecular And Electronic Structure Of Si3h6, Mark S. Gordon, David Bartol
Mark S. Gordon
The ground state of disilylsilylene ((SiH3)2Si) is predicted to be the closed-shell (lAin C2 symmetry) state, about 6 kcal/mol below the lowest triplet es, in C2v symmetry) at the MP4/6-31 0( d) //3-21 0* level of theory. A second triplet with a very small Si-Si-Si angle e A in C2 symmetry) is found to be more than 30 kcal/mol above the ground state. The global minimum on the Si3H6 ground-state surface is predicted to be trisilacyclopropane, 18.3 and 9.7 kcalfmol, respectively, below (SiH3)2Si and SiH3SiH=SiH2•
Ab Initio Calculations On Some C3sih4 Isomers, George W. Schriver, Mark J. Fink, Mark S. Gordon
Ab Initio Calculations On Some C3sih4 Isomers, George W. Schriver, Mark J. Fink, Mark S. Gordon
Mark S. Gordon
Restricted Hartree-Fock ab initio calculations have been performed on various isomers of silacyclobutadiene (C3SiH 4). Geometry optimizations were performed by using various basis sets. Geometric results were similar, but proper description of relative energies required the larger 6-31G* basis. Calculations treating election correlation at the MP2 level were performed on the seven lowest energy structures. These calculations gave similar results. The most stable species found is 2-methylsilacycloprop-2-en-1-ylidene. Silacyclobutadiene is almost 60 kcal mol- 1 less stable, while silatetrahedrane lies a further 32 kcal mol-1 higher in energy. The most stable isomer with normal valence is 2-silabut-1-en-3-yne, 28.2 kcal mol-1 above …
Π Bond Strengths In The Second And Third Periods, Michael W. Schmidt, Phi N. Truong, Mark S. Gordon
Π Bond Strengths In The Second And Third Periods, Michael W. Schmidt, Phi N. Truong, Mark S. Gordon
Mark S. Gordon
All possible pi bonds formed between the elements C, N, 0, Si, P, and S are considered. The pi bond strengths are estimated by the cis-trans rotation barriers (where possible) and by hydrogenation energies. The ability of these elements to form strong pibonds is in the order 0 > N "" C » S > P > Si. In addition, computed bond lengths and vibrational stretching frequencies are reported for both the singly and doubly bound compounds. The structure of the lowest triplet state of each double-bonded compound is given, along with the singlet-triplet splitting.
Thermal Decomposition Of Methanethiol And Ethanethiol, Kim K. Baldridge, Mark S. Gordon, Douglas E. Johnson
Thermal Decomposition Of Methanethiol And Ethanethiol, Kim K. Baldridge, Mark S. Gordon, Douglas E. Johnson
Mark S. Gordon
Selected ground-state decomposition pathways for methanethiol and ethanethiol are considered, using ab initio electronic structure calculations including electron correlation. The decomposition of methanethiol to form methylene and hydrogen sulfide requires a large activation energy (108.3 kcaljmol). In contrast, the energy required for the homolytic cleavage of the C-S bond is calculated to be just 67.2 kcaljmol. For ethanethiol, carbene formation is more competitive with radical processes. Here, the activation energy for the 1,1 elimination of H2S to form ethylidene (76.9 kcaljmol) is smaller than that for the direct formation of ethylene via a 1,2 elimination (106.6 kcaljmol) and only 12 …
Post-Effect Of Ammonia On Energetics Of Laying Hens At High Temperatures, Hongwei Xin, James A. Deshazer, M. M. Beck
Post-Effect Of Ammonia On Energetics Of Laying Hens At High Temperatures, Hongwei Xin, James A. Deshazer, M. M. Beck
Hongwei Xin
Leghorn layers were monitored for heat loss, feed intake, egg production and respiratory rate at various environmental temperatures (TJ after first being exposed to aerial ammonia (NH3). The initial exposure was to 10 or 60 ppm NH3 at a T, of 25 °C for 30 days to simulate a winter environmental condition in a poultry facility. Hens were then allowed to recover in an environment of 5 ppm of NH3 at a T^ of 22 °C for seven days to simulate a spring environmental condition. Birds were then placed individually in a partitional calorimeter free of NH3 at 25, 29, …
Molecular-Marker-Facilitated Investigations Of Quantitative-Trait Loci In Maize. I. Numbers, Genomic Distribution And Types Of Gene Action, Jonathan F. Wendel, M. D. Edwards, Charles W. Stuber
Molecular-Marker-Facilitated Investigations Of Quantitative-Trait Loci In Maize. I. Numbers, Genomic Distribution And Types Of Gene Action, Jonathan F. Wendel, M. D. Edwards, Charles W. Stuber
Jonathan F. Wendel
Individual genetic factors which underlie variation in quantitative traits of maize were investigated in each of two F 2 populations by examining the mean trait expressions of genotypic classes at each of 17-20 segregating marker loci. It was demonstrated that the trait expression of marker locus classes could be interpreted in terms of genetic behavior at linked quantitative trait loci (QTLs). For each of 82 traits evaluated, QTLs were detected and located to genomic sites. The numbers of detected factors varied according to trait, with the average trait significantly influenced by almost two-thirds of the marked genomic sites. Most of …
Heats Of Formation For Third-Period Hydrides: Test Of An Extended Basis Set, Mark S. Gordon, John Heitzinger
Heats Of Formation For Third-Period Hydrides: Test Of An Extended Basis Set, Mark S. Gordon, John Heitzinger
Mark S. Gordon
The extended basis set developed by McLean and Chandler for third-period atoms is combined with the -311G hydrogen basis and augmented by polarization functions to predict the heats of formation of third-period hydrides at the full MP4 computational level. The calculated heats of formation are at least as accurate as those predicted for second-row hydrides by using MP4/6-311G(d,p) wave functions, with a root mean square error of approximately 4 kcaljmol.
Ground-State Potential Energy Surface Of Phosphine Oxide, Jerry A. Boatz, Michael W. Schmidt, Mark S. Gordon
Ground-State Potential Energy Surface Of Phosphine Oxide, Jerry A. Boatz, Michael W. Schmidt, Mark S. Gordon
Mark S. Gordon
A network of elimination reactions of H3PO in its ground state is examined by using ab initio (3-21G* and 6-31G** with MP3 perturbation corrections) wave functions. In addition to the eliminations, several isomerizations and internal rotations of the parent compound and its fragments are investigated. The insertion and reactive scattering reactions of H2 + HPO, which are characterized more fully with MP4(SDTQ) perturbation corrections, are followed by using the intrinsic reaction coordinate and energy-localized orbitals.
Insertion Of Methylene Into Ethane And Cyclopropane, Mark S. Gordon, J. A. Boatz, David R. Gano, Marie G. Friederichs
Insertion Of Methylene Into Ethane And Cyclopropane, Mark S. Gordon, J. A. Boatz, David R. Gano, Marie G. Friederichs
Mark S. Gordon
The insertions of methylene into the CH and CC bonds of ethane and into a CC bond of cyclopropane are calculated by using third-order perturbation theory with the 6-31G(d) basis set. At this level of theory, the barriers for these reactions are predicted to be 0.2, 46.0, and 2.2 kcaljmol, respectively. Thus, the introduction of strain has a dramatic effect on the barrier to insertion into a heavy atom-heavy atom bond.
Potential Energy Surfaces For Polyatomic Reaction Dynamics, Donald G. Truhlar, Rozeanne Steckler, Mark S. Gordon
Potential Energy Surfaces For Polyatomic Reaction Dynamics, Donald G. Truhlar, Rozeanne Steckler, Mark S. Gordon
Mark S. Gordon
The last few years have seen an explosive growth of interest in detailed studies of polyatomic reaction dynamics. Improved experimental techniques, more powerful semiclassical dynamical methods, and accurate electronic structure capabilities have all combined to focus attention on detailed dynamical questions for larger and larger systems. Many of these questions have previously been tackled primarily for atom-diatom or diatom-diatom collisions or isolated triatomics. 1- 5 Although of course the final word on such simpler systems has not been said (and never will be), we will focus in the present review on more complicated cases. Thus the "polyatomic" in the title …
Responses Of Africanized Honey Bees Hymenoptera Apidae To Pollination Management Stress, Robert G. Danka, Thomas E. Rinderer, Anita M. Collins, Richard L. Hellmich Ii
Responses Of Africanized Honey Bees Hymenoptera Apidae To Pollination Management Stress, Robert G. Danka, Thomas E. Rinderer, Anita M. Collins, Richard L. Hellmich Ii
Richard L Hellmich
Fifteen Africanized (AHB) and 15 European (EHB) honey bee, Apis mellifera L., colonies were moved to six different crop sites during a 2-mo test in Venezuela. Several problems with AHB suggested that these bees may be difficult to use commerically for pollination. Debilitating reductions of adult populations occurred more frequently among AHB colonies (n = 12) than among EHB colonies (n = 5). In 6 of 11 tests of defensive response, targets were stung more by AHB colonies than by EHB colonies; no differences were found in the five other stinging comparisons. Also during defense tests, AHB colonies typically had …
Differential Drone Production By Africanized And European Honey Bee Colonies, Thomas E. Rinderer, Anita M. Collins, Richard L. Hellmich Ii, Robert G. Danka
Differential Drone Production By Africanized And European Honey Bee Colonies, Thomas E. Rinderer, Anita M. Collins, Richard L. Hellmich Ii, Robert G. Danka
Richard L Hellmich
The numbers of mature drones leaving colonies of Africanized and European honey bees were counted after they had been trapped at colony entrances. Two apiaries, each with 10 European and 10 Africanized colonies, were trapped for drones exiting individual colonies on 3 separate days at two week intervals. Africanized colonies maintained far more drones and far more Africanized drones parasitized European colonies than vice versa. These two factors resulted in 91% of the drones leaving colonies in the apiaries being Africanized.
Fish Acute Toxicity Syndromes And Their Use In The Qsar Approach To Hazard Assessment, Steven P. Bradbury, James M. Mckim, Gerald J. Niemi
Fish Acute Toxicity Syndromes And Their Use In The Qsar Approach To Hazard Assessment, Steven P. Bradbury, James M. Mckim, Gerald J. Niemi
Steven P. Bradbury
Implementation of the Toxic Substances Control Act of 1977 creates the need to reliably establish testing priorities because laboratory resources are limited and the number of industrial chemicals requiring evaluation is overwhelming. The use of quantitative structure activity relationship (QSAR) models as rapid and predictive screening tools to select more potentially hazardous chemicals for in-depth laboratory evaluation has been proposed. Further implementation and refinement of quantitative structure-toxicity relationships in aquatic toxicology and hazard assessment requires the development of a "mode-of-action" database. With such a database, a qualitative structure-activity relationship can be formulated to assign the proper mode of action, and …
Physiological Response Of Rainbow Trout (Salmo Gairdneri) To Acute Fenvalerate Lntoxication, Steven P. Bradbury, James M. Mckim, Joel R. Coats
Physiological Response Of Rainbow Trout (Salmo Gairdneri) To Acute Fenvalerate Lntoxication, Steven P. Bradbury, James M. Mckim, Joel R. Coats
Steven P. Bradbury
The physiological responses of rainbow trout (Salmo gairdneri) to fenvalerate intoxication during aqueous exposure were examined to provide information about the pyrethroid mode of action in fish. Trout (n = 4) were exposed to 412 ± 50 μg/liter fenvalerate and died in 10.9 ± 1.5 hr. Brain, liver, and carcass fenvalerate concentrations associated with mortality were 0.16 ± 0.05, 3.62 ± 0.57, and 0.25 ± 0.05 mg/kg, respectively. Visible signs of intoxication included elevated cough rate, tremors, and seizures. Histopathological examination of gill tissue showed damage consistent with irritation. An evaluation of respiratory-cardiovascular and blood chemistry responses indicated an elevated …
Improved Simple Techniques For Identifying Africanized And European Honey Bees, Thomas E. Rinderer, H. Allen Sylvester, Steven M. Buco, Vicki A. Lancaster, Elton W. Herbert, Anita M. Collins, Richard L. Hellmich Ii
Improved Simple Techniques For Identifying Africanized And European Honey Bees, Thomas E. Rinderer, H. Allen Sylvester, Steven M. Buco, Vicki A. Lancaster, Elton W. Herbert, Anita M. Collins, Richard L. Hellmich Ii
Richard L Hellmich
Eight simple techniques based on discriminant statistical procedures are presented to identify Africanized and European bees in the Americas. These techniques arc based on measurements of forewing lengths, the wet and dry weights of degastered bees, and femur lengths. Improved methodologies and statistical procedures result in many more correct identifications at high probabilities of class membership.
The Further Geometry Of Grain Boundaries In Hexagonal Close-Packed Metals, Fu-Rong Chen, Alexander H. King
The Further Geometry Of Grain Boundaries In Hexagonal Close-Packed Metals, Fu-Rong Chen, Alexander H. King
Alexander H. King
A technique is given for finding partial DSC vectors appropriate to crystals with more than one atom per lattice site. The DSC lattice is made up of vectors that represent displacements of one crystal with respect to the other that leave the boundary structure shifted, but not complete. A new, rapid method for finding the step vectors associated with perfect DSC dislocations is described. Partial DSC vectors and step vectors for perfect DSC dislocations in hexagonal close-packed crystals are determined. The availability of reactions between lattice partial dislocations and grain boundaries in hexagonal close-packed crystals is also assessed.
Calculated High‐Pressure Properties Of Solid Acetylene And Possible Polymerization Paths, Richard Alan Lesar
Calculated High‐Pressure Properties Of Solid Acetylene And Possible Polymerization Paths, Richard Alan Lesar
Richard Alan Lesar
Results of theoretical calculations at 0 K on the two known structures of solid acetylene using the modified Gordon–Kim plus damped dispersion model are reported. The lattice energy of the low temperature C m c astructure is compared to that of the high temperature P a3 structure at zero pressure and found to be slightly less stable, though a very small pressure (about 0.25 kbar) stabilizes the C m c astructure relative to the P a3 structure. Agreement between the experimental structure and energy for the C m c astructure and our present results is good. Structural properties of the …
Ultrasonic Nondestructive Evaluation Of Fibre-Reinforced Composite Materials - A Review, Vikram K. Kinra, Vinay Dayal
Ultrasonic Nondestructive Evaluation Of Fibre-Reinforced Composite Materials - A Review, Vikram K. Kinra, Vinay Dayal
Vinay Dayal
This paper reviews various ultrasonic nondestructive evaluation techniques applicable to fibre-reinforced composites. The techniques are briefly described and key references are cited. Methods to evaluate the reduced stiffness of composites due to micro-damage are described. Results show that for composites through-the-thickness attenuation increases and stiffness does not change due to transverse cracks, but in-plane stiffness and attenuation changes are substantial and can be measured by the Lamb wave techniques.
Vibrational Frequency Shifts In Dense Molecular Fluids, Richard Alan Lesar
Vibrational Frequency Shifts In Dense Molecular Fluids, Richard Alan Lesar
Richard Alan Lesar
A theory is presented for calculating the bond length and vibrational frequency shifts in dense molecular fluids. We combine equation‐of‐state calculations based on the effective spherical potentials of Shaw, Johnson, and co‐workers with a simple model for the interactions of a molecule with the surrounding fluid. The repulsive interactions are approximated with the hard‐sphere model of Schweizer and Chandler. We extend their model by including an improved treatment of the long‐range attractive interactions and the centrifugal forces. We apply this model to fluid nitrogen and compare with static and shock wave experimental frequency shifts, as well as computer simulation data, …
Forage Quality Of Perennial Glandular-Haired And Eglandular Medicago Populations, Andrew W. Lenssen
Forage Quality Of Perennial Glandular-Haired And Eglandular Medicago Populations, Andrew W. Lenssen
Andrew W. Lenssen
No abstract provided.
Interaction Between Magnetic And Compositional Order In Ni‐Rich Ni C Fe1−C Alloys (Invited), J. B. Staunton, Duane D. Johnson, B. L. Gyorffy
Interaction Between Magnetic And Compositional Order In Ni‐Rich Ni C Fe1−C Alloys (Invited), J. B. Staunton, Duane D. Johnson, B. L. Gyorffy
Duane D. Johnson
We have developed a first‐principles electronic theory of concentration fluctuations in spin polarized binary alloys. It is a mean field theory of the state of compositional order and it is based on the local spin density (LSD) approximation for describing the electrons. The usual averages over the statistical mechanical ensemble are carried out with the aid of the self‐consistent Korringe–Kohn–Rostoker coherent‐potential approximation (SCF‐KKR‐CPA). To illustrate the main consequences of the theory we study the compositional short‐range order in the Ni c Fe1−c alloy system. We find that the ordering energy is almost entirely of magnetic origin.
Estimating The Value Of Water Quality Improvements In A Recreational Demand Framework, Nancy E. Bockstael, Catherine Kling, W. Michael Hanemann
Estimating The Value Of Water Quality Improvements In A Recreational Demand Framework, Nancy E. Bockstael, Catherine Kling, W. Michael Hanemann
Catherine Kling
With the advent of Executive Order 12291, policymakers involved in water quality regulation are increasingly interested in assessing the benefits of their programs. Several methods for valuing water quality improvements using recreational demand models have been developed by economists, most of which depend on observing recreationists visiting an array of sites with varying water quality and costs of access. In this paper, three general types of models are described: systems of demands, discrete choice models, and the hedonic travel cost approach; the latter two models are demonstrated using a common data set on water quality and swimming behavior in the …