3D RISM theory with fast reciprocal-space electrostatics
Heil, Jochen; Kast, Stefan M.
2015-03-21
The calculation of electrostatic solute-solvent interactions in 3D RISM (“three-dimensional reference interaction site model”) integral equation theory is recast in a form that allows for a computational treatment analogous to the “particle-mesh Ewald” formalism as used for molecular simulations. In addition, relations that connect 3D RISM correlation functions and interaction potentials with thermodynamic quantities such as the chemical potential and average solute-solvent interaction energy are reformulated in a way that calculations of expensive real-space electrostatic terms on the 3D grid are completely avoided. These methodical enhancements allow for both, a significant speedup particularly for large solute systems and a smoother convergence of predicted thermodynamic quantities with respect to box size, as illustrated for several benchmark systems.
Du, Qi-Shi; Liu, Peng-Jun; Huang, Ri-Bo
2008-02-01
In this study the excess chemical potential of the integral equation theory, 3D-RISM-HNC [Q. Du, Q. Wei, J. Phys. Chem. B 107 (2003) 13463-13470], is visualized in three-dimensional form and localized at interaction sites of solute molecule. Taking the advantage of reference interaction site model (RISM), the calculation equations of chemical excess potential are reformulized according to the solute interaction sites s in molecular space. Consequently the solvation free energy is localized at every interaction site of solute molecule. For visualization of the 3D-RISM-HNC calculation results, the excess chemical potentials are described using radial and three-dimensional diagrams. It is found that the radial diagrams of the excess chemical potentials are more sensitive to the bridge functions than the radial diagrams of solvent site density distributions. The diagrams of average excess chemical potential provide useful information of solute-solvent electrostatic and van der Waals interactions. The local description of solvation free energy at active sites of solute in 3D-RISM-HNC may broaden the application scope of statistical mechanical integral equation theory in solution chemistry and life science.
Kiyota, Yasuomi; Yoshida, Norio; Hirata, Fumio
2011-11-08
A new approach to investigate a molecular recognition process of protein is presented based on the three-dimensional reference interaction site model (3D-RISM) theory, a statistical mechanics theory of molecular liquids. Numerical procedure for solving the conventional 3D-RISM equation consists of two steps. In step 1, we solve ordinary RISM (or 1D-RISM) equations for a solvent mixture including target ligands in order to obtain the density pair correlation functions (PCF) among molecules in the solution. Then, we solve the 3D-RISM equation for a solute-solvent system to find three-dimensional density distribution functions (3D-DDF) of solvent species around a protein, using PCF obtained in the first step. A key to the success of the method was to regard a target ligand as one of "solvent" species. However, the success is limited due to a difficulty of solving the 1D-RISM equation for a solvent mixture, including large ligand molecules. In the present paper, we propose a method which eases the limitation concerning solute size in the conventional method. In this approach, we solve a solute-solute 3D-RISM equations for a protein-ligand system in which both proteins and ligands are regarded as "solutes" at infinite dilution. The 3D- and 1D-RISM equations are solved for protein-solvent and ligand-solvent systems, respectively, in order to obtain the 3D- and 1D-DDF of solvent around the solutes, which are required for solving the solute-solute 3D-RISM equation. The method is applied to two practical and noteworthy examples concerning pharmaceutical design. One is an odorant binding protein in the Drosophila melanogaster , which binds an ethanol molecule. The other is phospholipase A2, which is known as a receptor of acetylsalicylic acid or aspirin. The result indicates that the method successfully reproduces the binding mode of the ligand molecules in the binding sites measured by the experiments.
Huang, WenJuan; Blinov, Nikolay; Kovalenko, Andriy
2015-04-30
The octanol-water partition coefficient is an important physical-chemical characteristic widely used to describe hydrophobic/hydrophilic properties of chemical compounds. The partition coefficient is related to the transfer free energy of a compound from water to octanol. Here, we introduce a new protocol for prediction of the partition coefficient based on the statistical-mechanical, 3D-RISM-KH molecular theory of solvation. It was shown recently that with the compound-solvent correlation functions obtained from the 3D-RISM-KH molecular theory of solvation, the free energy functional supplemented with the correction linearly related to the partial molar volume obtained from the Kirkwood-Buff/3D-RISM theory, also called the "universal correction" (UC), provides accurate prediction of the hydration free energy of small compounds, compared to explicit solvent molecular dynamics [ Palmer , D. S. ; J. Phys.: Condens. Matter 2010 , 22 , 492101 ]. Here we report that with the UC reparametrized accordingly this theory also provides an excellent agreement with the experimental data for the solvation free energy in nonpolar solvent (1-octanol) and so accurately predicts the octanol-water partition coefficient. The performance of the Kovalenko-Hirata (KH) and Gaussian fluctuation (GF) functionals of the solvation free energy, with and without UC, is tested on a large library of small compounds with diverse functional groups. The best agreement with the experimental data for octanol-water partition coefficients is obtained with the KH-UC solvation free energy functional.
Miyata, Tatsuhiko; Hirata, Fumio
2008-04-30
We have developed an algorithm for sampling the conformational space of large flexible molecules in solution, which combines the molecular dynamics (MD) method and the three-dimensional reference interaction site model (3D-RISM) theory. The solvent-induced force acting on solute atoms was evaluated as the gradient of the solvation free energy with respect to the solute-atom coordinates. To enhance the computation speed, we have applied a multiple timestep algorithm based on the RESPA (Reversible System Propagator Algorithm) to the combined MD/3D-RISM method. By virtue of the algorithm, one can choose a longer timestep for renewing the solvent-induced force compared with that of the conformational update. To illustrate the present MD/3D-RISM simulation, we applied the method to a model of acetylacetone in aqueous solution. The multiple timestep algorithm succeeded in enhancing the computation speed by 3.4 times for this model case. Acetylacetone possesses an intramolecular hydrogen-bonding capability between the hydroxyl group and the carbonyl oxygen atom, and the molecule is significantly stabilized due to this hydrogen bond, especially in gas phase. The intramolecular hydrogen bond was kept intact during almost entire course of the MD simulation in gas phase, while in the aqueous solutions the bond is disrupted in a significant number of conformations. This result qualitatively agrees with the behavior on a free energy barrier lying upon the process for rotating a torsional degree of freedom of the hydroxyl group, where it is significantly reduced in aqueous solution by a cancellation between the electrostatic interaction and the solvation free energy.
NASA Astrophysics Data System (ADS)
Tikhonov, D. A.; Sobolev, E. V.
2011-04-01
A method of integral equations of the theory of liquids in the reference interaction site model (RISM) approximation is used to estimate the Gibbs energy averaged over equilibrium trajectories computed by molecular mechanics. Peptide oxytocin is selected as the object of interest. The Gibbs energy is calculated using all chemical potential formulas introduced in the RISM approach for the excess chemical potential of solvation and is compared with estimates by the generalized Born model. Some formulas are shown to give the wrong sign of Gibbs energy changes when peptide passes from the gas phase into water environment; the other formulas give overestimated Gibbs energy changes with the right sign. Note that allowance for the repulsive correction in the approximate analytical expressions for the Gibbs energy derived by thermodynamic perturbation theory is not a remedy.
Stumpe, Martin C.; Blinov, Nikolay; Wishart, David; Kovalenko, Andriy; Pande, Vijay S.
2010-01-01
Water plays a unique role in all living organisms. Not only is it nature’s ubiquitous solvent, but it also actively takes part in many cellular processes. In particular, the structure and properties of interfacial water near biomolecules like proteins are often related to the function of the respective molecule. It can therefore be highly instructive to study the local water density around solutes in cellular systems, particularly when solvent-mediated forces like the hydrophobic effect are relevant. Computational methods like molecular dynamics (MD) simulations seem well suited to study these systems at the atomic level. However, due to sampling requirements, it is not clear that MD simulations are indeed the method of choice to obtain converged densities at a given level of precision. We here compare the calculation of local water densities with two different methods, MD simulations and the three-dimensional reference interaction site model with the Kovalenko-Hirata closure (3D-RISM-KH). In particular, we investigate the convergence of the local water density to assess the required simulation times for different levels of resolution. Moreover, we provide a quantitative comparison of the densities calculated with MD and with 3D-RISM-KH, and investigate the effect of the choice of the water model for both methods. Our results show that 3D-RISM-KH yields density distributions that are very similar to those from MD up to a 0.5 Å resolution, but for significantly reduced computational cost. The combined use of MD and 3D-RISM-KH emerges as an auspicious perspective for efficient solvent sampling in dynamical systems. PMID:21174421
Imai, Takashi; Kovalenko, Andriy; Hirata, Fumio; Kidera, Akinori
2009-06-01
It has been shown that trifluoroethanol (TFE) induces helical structure in peptides and proteins. The molecular mechanism is, however, still not completely elucidated. In this study, the TFE effects on the solvation structure and on the free energy change associated with the helix-coil transition of a polypeptide are analyzed by using the three-dimensional reference interaction site model (3D-RISM) molecular theory of solvation. The theoretical result shows that TFE preferentially solvates at low concentrations around 30 vol% both for the helix and coil structures. However, the characteristic preferential solvation is not as significant in the TFE-induced helix stabilization as generally considered. It is also found that the overall energy contributes to the free energy difference more substantially than the solvation entropy.
Range Information Systems Management (RISM) Phase 1 Report
NASA Technical Reports Server (NTRS)
Bastin, Gary L.; Harris, William G.; Nelson, Richard A.
2002-01-01
RISM investigated alternative approaches, technologies, and communication network architectures to facilitate building the Spaceports and Ranges of the future. RISM started by document most existing US ranges and their capabilities. In parallel, RISM obtained inputs from the following: 1) NASA and NASA-contractor engineers and managers, and; 2) Aerospace leaders from Government, Academia, and Industry, participating through the Space Based Range Distributed System Working Group (SBRDSWG), many of whom are also; 3) Members of the Advanced Range Technology Working Group (ARTWG) subgroups, and; 4) Members of the Advanced Spaceport Technology Working Group (ASTWG). These diverse inputs helped to envision advanced technologies for implementing future Ranges and Range systems that builds on today s cabled and wireless legacy infrastructures while seamlessly integrating both today s emerging and tomorrow s building-block communication techniques. The fundamental key is to envision a transition to a Space Based Range Distributed Subsystem. The enabling concept is to identify the specific needs of Range users that can be solved through applying emerging communication tech
NASA Astrophysics Data System (ADS)
Luchko, Tyler; Blinov, Nikolay; Limon, Garrett C.; Joyce, Kevin P.; Kovalenko, Andriy
2016-11-01
Implicit solvent methods for classical molecular modeling are frequently used to provide fast, physics-based hydration free energies of macromolecules. Less commonly considered is the transferability of these methods to other solvents. The Statistical Assessment of Modeling of Proteins and Ligands 5 (SAMPL5) distribution coefficient dataset and the accompanying explicit solvent partition coefficient reference calculations provide a direct test of solvent model transferability. Here we use the 3D reference interaction site model (3D-RISM) statistical-mechanical solvation theory, with a well tested water model and a new united atom cyclohexane model, to calculate partition coefficients for the SAMPL5 dataset. The cyclohexane model performed well in training and testing (R=0.98 for amino acid neutral side chain analogues) but only if a parameterized solvation free energy correction was used. In contrast, the same protocol, using single solute conformations, performed poorly on the SAMPL5 dataset, obtaining R=0.73 compared to the reference partition coefficients, likely due to the much larger solute sizes. Including solute conformational sampling through molecular dynamics coupled with 3D-RISM (MD/3D-RISM) improved agreement with the reference calculation to R=0.93. Since our initial calculations only considered partition coefficients and not distribution coefficients, solute sampling provided little benefit comparing against experiment, where ionized and tautomer states are more important. Applying a simple pK_{ {a}} correction improved agreement with experiment from R=0.54 to R=0.66, despite a small number of outliers. Better agreement is possible by accounting for tautomers and improving the ionization correction.
Luchko, Tyler; Blinov, Nikolay; Limon, Garrett C; Joyce, Kevin P; Kovalenko, Andriy
2016-11-01
Implicit solvent methods for classical molecular modeling are frequently used to provide fast, physics-based hydration free energies of macromolecules. Less commonly considered is the transferability of these methods to other solvents. The Statistical Assessment of Modeling of Proteins and Ligands 5 (SAMPL5) distribution coefficient dataset and the accompanying explicit solvent partition coefficient reference calculations provide a direct test of solvent model transferability. Here we use the 3D reference interaction site model (3D-RISM) statistical-mechanical solvation theory, with a well tested water model and a new united atom cyclohexane model, to calculate partition coefficients for the SAMPL5 dataset. The cyclohexane model performed well in training and testing ([Formula: see text] for amino acid neutral side chain analogues) but only if a parameterized solvation free energy correction was used. In contrast, the same protocol, using single solute conformations, performed poorly on the SAMPL5 dataset, obtaining [Formula: see text] compared to the reference partition coefficients, likely due to the much larger solute sizes. Including solute conformational sampling through molecular dynamics coupled with 3D-RISM (MD/3D-RISM) improved agreement with the reference calculation to [Formula: see text]. Since our initial calculations only considered partition coefficients and not distribution coefficients, solute sampling provided little benefit comparing against experiment, where ionized and tautomer states are more important. Applying a simple [Formula: see text] correction improved agreement with experiment from [Formula: see text] to [Formula: see text], despite a small number of outliers. Better agreement is possible by accounting for tautomers and improving the ionization correction.
Huš, Matej; Munaò, Gianmarco; Urbic, Tomaz
2014-01-01
Thermodynamic and structural properties of a coarse-grained model of methanol are examined by Monte Carlo simulations and reference interaction site model (RISM) integral equation theory. Methanol particles are described as dimers formed from an apolar Lennard-Jones sphere, mimicking the methyl group, and a sphere with a core-softened potential as the hydroxyl group. Different closure approximations of the RISM theory are compared and discussed. The liquid structure of methanol is investigated by calculating site-site radial distribution functions and static structure factors for a wide range of temperatures and densities. Results obtained show a good agreement between RISM and Monte Carlo simulations. The phase behavior of methanol is investigated by employing different thermodynamic routes for the calculation of the RISM free energy, drawing gas-liquid coexistence curves that match the simulation data. Preliminary indications for a putative second critical point between two different liquid phases of methanol are also discussed. PMID:25362323
Huš, Matej; Urbic, Tomaz; Munaò, Gianmarco
2014-10-28
Thermodynamic and structural properties of a coarse-grained model of methanol are examined by Monte Carlo simulations and reference interaction site model (RISM) integral equation theory. Methanol particles are described as dimers formed from an apolar Lennard-Jones sphere, mimicking the methyl group, and a sphere with a core-softened potential as the hydroxyl group. Different closure approximations of the RISM theory are compared and discussed. The liquid structure of methanol is investigated by calculating site-site radial distribution functions and static structure factors for a wide range of temperatures and densities. Results obtained show a good agreement between RISM and Monte Carlo simulations. The phase behavior of methanol is investigated by employing different thermodynamic routes for the calculation of the RISM free energy, drawing gas-liquid coexistence curves that match the simulation data. Preliminary indications for a putative second critical point between two different liquid phases of methanol are also discussed.
Cao, Siqin; Sheong, Fu Kit; Huang, Xuhui
2015-08-07
Reference interaction site model (RISM) has recently become a popular approach in the study of thermodynamical and structural properties of the solvent around macromolecules. On the other hand, it was widely suggested that there exists water density depletion around large hydrophobic solutes (>1 nm), and this may pose a great challenge to the RISM theory. In this paper, we develop a new analytical theory, the Reference Interaction Site Model with Hydrophobicity induced density Inhomogeneity (RISM-HI), to compute solvent radial distribution function (RDF) around large hydrophobic solute in water as well as its mixture with other polyatomic organic solvents. To achieve this, we have explicitly considered the density inhomogeneity at the solute-solvent interface using the framework of the Yvon-Born-Green hierarchy, and the RISM theory is used to obtain the solute-solvent pair correlation. In order to efficiently solve the relevant equations while maintaining reasonable accuracy, we have also developed a new closure called the D2 closure. With this new theory, the solvent RDFs around a large hydrophobic particle in water and different water-acetonitrile mixtures could be computed, which agree well with the results of the molecular dynamics simulations. Furthermore, we show that our RISM-HI theory can also efficiently compute the solvation free energy of solute with a wide range of hydrophobicity in various water-acetonitrile solvent mixtures with a reasonable accuracy. We anticipate that our theory could be widely applied to compute the thermodynamic and structural properties for the solvation of hydrophobic solute.
Cao, Siqin; Sheong, Fu Kit; Huang, Xuhui
2015-08-07
Reference interaction site model (RISM) has recently become a popular approach in the study of thermodynamical and structural properties of the solvent around macromolecules. On the other hand, it was widely suggested that there exists water density depletion around large hydrophobic solutes (>1 nm), and this may pose a great challenge to the RISM theory. In this paper, we develop a new analytical theory, the Reference Interaction Site Model with Hydrophobicity induced density Inhomogeneity (RISM-HI), to compute solvent radial distribution function (RDF) around large hydrophobic solute in water as well as its mixture with other polyatomic organic solvents. To achieve this, we have explicitly considered the density inhomogeneity at the solute-solvent interface using the framework of the Yvon-Born-Green hierarchy, and the RISM theory is used to obtain the solute-solvent pair correlation. In order to efficiently solve the relevant equations while maintaining reasonable accuracy, we have also developed a new closure called the D2 closure. With this new theory, the solvent RDFs around a large hydrophobic particle in water and different water-acetonitrile mixtures could be computed, which agree well with the results of the molecular dynamics simulations. Furthermore, we show that our RISM-HI theory can also efficiently compute the solvation free energy of solute with a wide range of hydrophobicity in various water-acetonitrile solvent mixtures with a reasonable accuracy. We anticipate that our theory could be widely applied to compute the thermodynamic and structural properties for the solvation of hydrophobic solute.
Schmeer, Georg; Maurer, Alexander
2010-03-14
We derived a formula of the chemical excess potential mu of electrolytes in solutions (NaCl, NaNO(3), Me(4)NCl) within the framework of the RISM model of liquid systems as a partial derivative of the Helmholtz energy with respect to the amount n(i) of the compound i. Since it is possible to perform RISM-calculations at very small electrolyte concentrations we compared the concentration dependence of the chemical excess potential with the Debye-Hückel limiting law. In general the concentration dependence of the chemical excess potential of the electrolytes follows the square-root law of Debye-Hückel. The slopes of these functions, however, need a very individual discussion. The HNC-closure relation yields a much too large slope due to the overwhelming electrostatic interaction, whereas the closure relation of Kovalenko and Hirata gives very promising results for atomic ions. According to the deficiencies of the RISM model of the SSOZ-theory the slope furnishes only a dielectric constant of water according to this model. Molecular ions, however, show larger deviations from the postulated concentration dependence.
The solvent effect on the acidities of haloacetic acids in aqueous solution. A RISM-SCF study
NASA Astrophysics Data System (ADS)
Kawata, Masaaki; Ten-no, Seiichiro; Kato, Shigeki; Hirata, Fumio
1995-06-01
The acidities of acetic, fluoracetic and chloroacetic acids in aqueous solution are calculated by means of the ab initio method combined with the reference interaction site method in the statistical mechanics of molecular liquids (the RISM-SCF method). The inversion in the order of acidities experimentally observed when a series of haloacetic acids is immersed into aqueous solution is reproduced. It is shown that the inversion is caused by competition between substitution and solvation effects. The solvation effect is discussed in molecular detail in terms of the charge distribution of the solute and the solute-solvent radial distribution functions.
Omelyan, Igor; Kovalenko, Andriy
2015-04-14
We developed a generalized solvation force extrapolation (GSFE) approach to speed up multiple time step molecular dynamics (MTS-MD) of biomolecules steered with mean solvation forces obtained from the 3D-RISM-KH molecular theory of solvation (three-dimensional reference interaction site model with the Kovalenko-Hirata closure). GSFE is based on a set of techniques including the non-Eckart-like transformation of coordinate space separately for each solute atom, extension of the force-coordinate pair basis set followed by selection of the best subset, balancing the normal equations by modified least-squares minimization of deviations, and incremental increase of outer time step in motion integration. Mean solvation forces acting on the biomolecule atoms in conformations at successive inner time steps are extrapolated using a relatively small number of best (closest) solute atomic coordinates and corresponding mean solvation forces obtained at previous outer time steps by converging the 3D-RISM-KH integral equations. The MTS-MD evolution steered with GSFE of 3D-RISM-KH mean solvation forces is efficiently stabilized with our optimized isokinetic Nosé-Hoover chain (OIN) thermostat. We validated the hybrid MTS-MD/OIN/GSFE/3D-RISM-KH integrator on solvated organic and biomolecules of different stiffness and complexity: asphaltene dimer in toluene solvent, hydrated alanine dipeptide, miniprotein 1L2Y, and protein G. The GSFE accuracy and the OIN efficiency allowed us to enlarge outer time steps up to huge values of 1-4 ps while accurately reproducing conformational properties. Quasidynamics steered with 3D-RISM-KH mean solvation forces achieves time scale compression of conformational changes coupled with solvent exchange, resulting in further significant acceleration of protein conformational sampling with respect to real time dynamics. Overall, this provided a 50- to 1000-fold effective speedup of conformational sampling for these systems, compared to conventional MD
Competitive interaction of monovalent cations with DNA from 3D-RISM
Giambaşu, George M.; Gebala, Magdalena K.; Panteva, Maria T.; Luchko, Tyler; Case, David A.; York, Darrin M.
2015-01-01
The composition of the ion atmosphere surrounding nucleic acids affects their folding, condensation and binding to other molecules. It is thus of fundamental importance to gain predictive insight into the formation of the ion atmosphere and thermodynamic consequences when varying ionic conditions. An early step toward this goal is to benchmark computational models against quantitative experimental measurements. Herein, we test the ability of the three dimensional reference interaction site model (3D-RISM) to reproduce preferential interaction parameters determined from ion counting (IC) experiments for mixed alkali chlorides and dsDNA. Calculations agree well with experiment with slight deviations for salt concentrations >200 mM and capture the observed trend where the extent of cation accumulation around the DNA varies inversely with its ionic size. Ion distributions indicate that the smaller, more competitive cations accumulate to a greater extent near the phosphoryl groups, penetrating deeper into the grooves. In accord with experiment, calculated IC profiles do not vary with sequence, although the predicted ion distributions in the grooves are sequence and ion size dependent. Calculations on other nucleic acid conformations predict that the variation in linear charge density has a minor effect on the extent of cation competition. PMID:26304542
Massively parallel implementation of 3D-RISM calculation with volumetric 3D-FFT.
Maruyama, Yutaka; Yoshida, Norio; Tadano, Hiroto; Takahashi, Daisuke; Sato, Mitsuhisa; Hirata, Fumio
2014-07-05
A new three-dimensional reference interaction site model (3D-RISM) program for massively parallel machines combined with the volumetric 3D fast Fourier transform (3D-FFT) was developed, and tested on the RIKEN K supercomputer. The ordinary parallel 3D-RISM program has a limitation on the number of parallelizations because of the limitations of the slab-type 3D-FFT. The volumetric 3D-FFT relieves this limitation drastically. We tested the 3D-RISM calculation on the large and fine calculation cell (2048(3) grid points) on 16,384 nodes, each having eight CPU cores. The new 3D-RISM program achieved excellent scalability to the parallelization, running on the RIKEN K supercomputer. As a benchmark application, we employed the program, combined with molecular dynamics simulation, to analyze the oligomerization process of chymotrypsin Inhibitor 2 mutant. The results demonstrate that the massive parallel 3D-RISM program is effective to analyze the hydration properties of the large biomolecular systems.
A theory of diffusion controlled reactions in polyatomic molecule system
NASA Astrophysics Data System (ADS)
Kasahara, Kento; Sato, Hirofumi
2016-11-01
The conventional Smoluchowski equation has been extensively utilized to investigate diffusion controlled reactions. However, application of the equation is limited to spherical-particle system. In the present study, a new Smoluchowski equation for polyatomic molecular system is derived based on Zwanzig-Mori projection operator method and reference interaction site model (RISM) theory. The theory is applied to monoatomic molecular liquid, and the obtained time-dependent rate constant is virtually identical with that from conventional Smoluchowski equation. For diatomic molecular liquid, time-dependent distribution function and rate constant are obtained, showing a good agreement with those from molecular dynamics simulation.
Nishiyama, Katsura; Watanabe, Yasuhiro; Yoshida, Norio; Hirata, Fumio
2013-09-07
The Stokes shift magnitudes for coumarin 153 (C153) in 13 organic solvents with various polarities have been determined by means of steady-state spectroscopy and reference interaction-site model-self-consistent-field (RISM-SCF) theory. RISM-SCF calculations have reproduced experimental results fairly well, including individual solvent characteristics. It is empirically known that in some solvents, larger Stokes shift magnitudes are detected than anticipated on the basis of the solvent relative permittivity, ɛr. In practice, 1,4-dioxane (ɛr = 2.21) provides almost identical Stokes shift magnitudes to that of tetrahydrofuran (THF, ɛr = 7.58), for C153 and other typical organic solutes. In this work, RISM-SCF theory has been used to estimate the energetics of C153-solvent systems involved in the absorption and fluorescence processes. The Stokes shift magnitudes estimated by RISM-SCF theory are ∼5 kJ mol(-1) (400 cm(-1)) less than those determined by spectroscopy; however, the results obtained are still adequate for dipole moment comparisons, in a qualitative sense. We have also calculated the solute-solvent site-site radial distributions by this theory. It is shown that solvation structures with respect to the C-O-C framework, which is common to dioxane and THF, in the near vicinity (∼0.4 nm) of specific solute sites can largely account for their similar Stokes shift magnitudes. In previous works, such solute-solvent short-range interactions have been explained in terms of the higher-order multipole moments of the solvents. Our present study shows that along with the short-range interactions that contribute most significantly to the energetics, long-range electrostatic interactions are also important. Such long-range interactions are effective up to 2 nm from the solute site, as in the case of a typical polar solvent, acetonitrile.
Information Theory and the Earth's Density Distribution
NASA Technical Reports Server (NTRS)
Rubincam, D. P.
1979-01-01
An argument for using the information theory approach as an inference technique in solid earth geophysics. A spherically symmetric density distribution is derived as an example of the method. A simple model of the earth plus knowledge of its mass and moment of inertia lead to a density distribution which was surprisingly close to the optimum distribution. Future directions for the information theory approach in solid earth geophysics as well as its strengths and weaknesses are discussed.
Ratkova, Ekaterina L; Fedorov, Maxim V
2011-05-10
Here, we discuss a new method for predicting the hydration free energy (HFE) of organic pollutants and illustrate the efficiency of the method on a set of 220 chlorinated aromatic hydrocarbons. The new model is computationally inexpensive, with one HFE calculation taking less than a minute on a PC. The method is based on a combination of a molecular integral equations theory, one-dimensional reference interaction site model (1D RISM), with the cheminformatics approach. We correct HFEs obtained by the 1D RISM with a set of empirical corrections. The corrections are associated with the partial molar volume and structural descriptors of the molecules. We show that the introduced corrections can significantly improve the quality of the 1D RISM HFE predictions obtained by the partial wave free energy expression [ Ten-no , S. J. Chem. Phys. 2001 , 115 , 3724 ] and the Kovalenko-Hirata closure [ Kovalenko , A. ; Hirata , F. J. Chem. Phys. 1999 , 110 , 10095 ]. We also show that the quality of the model can be further improved by the reparametrization using QM-derived partial charges instead of the originally used OPLS-AA partial charges. The final model gives good results for polychlorinated benzenes (the mean and standard deviation of the error are 0.02 and 0.36 kcal/mol, correspondingly). At the same time, the model gives somewhat worse results for polychlorobiphenyls (PCBs) with a systematic bias of -0.72 kcal/mol but a small standard deviation equal to 0.55 kcal/mol. We note that the error remains the same for the whole set of PCBs, whereas errors of HFEs predicted with continuum solvation models (data were taken from Phillips , K. L. et al. Environ. Sci. Technol. 2008 , 42 , 8412 ) increase significantly for higher chlorinated PCB congeners. In conclusion, we discuss potential future applications of the model and several avenues for its further improvement.
Information theory and the earth's density distribution
NASA Technical Reports Server (NTRS)
Rubincam, D. P.
1978-01-01
The present paper argues for using the information theory approach as an inference technique in solid earth geophysics. A spherically symmetric density distribution is derived as an example of the method. A simple model of the earth plus knowledge of its mass and moment of inertia leads to a density distribution. Future directions for the information theory approach in solid earth geophysics as well as its strengths and weaknesses are discussed.
ON THE DISTRIBUTION THEORY FOR SOME CONSTRAINED LIFE TESTING EXPERIMENTS.
RELIABILITY, *TEST METHODS, * DISTRIBUTION THEORY , MATHEMATICAL MODELS, STATISTICAL DISTRIBUTIONS, MULTIVARIATE ANALYSIS, DECISION THEORY, LIFE EXPECTANCY(SERVICE LIFE), EXPONENTIAL FUNCTIONS, THESES.
A Cavity Corrected 3D-RISM Functional for Accurate Solvation Free Energies
2014-01-01
We show that an Ng bridge function modified version of the three-dimensional reference interaction site model (3D-RISM-NgB) solvation free energy method can accurately predict the hydration free energy (HFE) of a set of 504 organic molecules. To achieve this, a single unique constant parameter was adjusted to the computed HFE of single atom Lennard-Jones solutes. It is shown that 3D-RISM is relatively accurate at predicting the electrostatic component of the HFE without correction but requires a modification of the nonpolar contribution that originates in the formation of the cavity created by the solute in water. We use a free energy functional with the Ng scaling of the direct correlation function [Ng, K. C. J. Chem. Phys.1974, 61, 2680]. This produces a rapid, reliable small molecule HFE calculation for applications in drug design. PMID:24634616
CI therapy distribution: theory, evidence and practice.
Sterr, Annette; Saunders, Amy
2006-01-01
Traditional rehabilitation for hemiplegia is not necessarily based on a supported theoretical foundation and some evidence questiones the efficacy of current practice. The uncertainty relating to underlying theories is a serious issue, henceforth there has been a move to base treatment strategies on scientific foundations which incorporate knowledge of human learning mechanisms and accompanying neurobiological processes. In this paper we argue that constraint induced movement therapy is a potentially very effective intervention that benefits from a strong theoretical grounding. It is demonstrated that the treatment mechanisms are supported by established behavioural learning theory and evidence of brain plasticity. As empirical support for the therapy is gradually mounting, the integration into mainstream practice lends itself as a natural course. In this paper, a series of issues surrounding the distribution of CIT such as constraint use, dose response relationships and accessibility to a wider group of patients are discussed. Further research in these areas is considered important for CIT integration into mainstream practice.
A closure relation to molecular theory of solvation for macromolecules
NASA Astrophysics Data System (ADS)
Kobryn, Alexander E.; Gusarov, Sergey; Kovalenko, Andriy
2016-10-01
We propose a closure to the integral equations of molecular theory of solvation, particularly suitable for polar and charged macromolecules in electrolyte solution. This includes such systems as oligomeric polyelectrolytes at a finite concentration in aqueous and various non-aqueous solutions, as well as drug-like compounds in solution. The new closure by Kobryn, Gusarov, and Kovalenko (KGK closure) imposes the mean spherical approximation (MSA) almost everywhere in the solvation shell but levels out the density distribution function to zero (with the continuity at joint boundaries) inside the repulsive core and in the spatial regions of strong density depletion emerging due to molecular associative interactions. Similarly to MSA, the KGK closure reduces the problem to a linear equation for the direct correlation function which is predefined analytically on most of the solvation shells and has to be determined numerically on a relatively small (three-dimensional) domain of strong depletion, typically within the repulsive core. The KGK closure leads to the solvation free energy in the form of the Gaussian fluctuation (GF) functional. We first test the performance of the KGK closure coupled to the reference interaction site model (RISM) integral equations on the examples of Lennard-Jones liquids, polar and nonpolar molecular solvents, including water, and aqueous solutions of simple ions. The solvation structure, solvation chemical potential, and compressibility obtained from RISM with the KGK closure favorably compare to the results of the hypernetted chain (HNC) and Kovalenko-Hirata (KH) closures, including their combination with the GF solvation free energy. We then use the KGK closure coupled to RISM to obtain the solvation structure and thermodynamics of oligomeric polyelectrolytes and drug-like compounds at a finite concentration in electrolyte solution, for which no convergence is obtained with other closures. For comparison, we calculate their solvation
Solvation effects on chemical shifts by embedded cluster integral equation theory.
Frach, Roland; Kast, Stefan M
2014-12-11
The accurate computational prediction of nuclear magnetic resonance (NMR) parameters like chemical shifts represents a challenge if the species studied is immersed in strongly polarizing environments such as water. Common approaches to treating a solvent in the form of, e.g., the polarizable continuum model (PCM) ignore strong directional interactions such as H-bonds to the solvent which can have substantial impact on magnetic shieldings. We here present a computational methodology that accounts for atomic-level solvent effects on NMR parameters by extending the embedded cluster reference interaction site model (EC-RISM) integral equation theory to the prediction of chemical shifts of N-methylacetamide (NMA) in aqueous solution. We examine the influence of various so-called closure approximations of the underlying three-dimensional RISM theory as well as the impact of basis set size and different treatment of electrostatic solute-solvent interactions. We find considerable and systematic improvement over reference PCM and gas phase calculations. A smaller basis set in combination with a simple point charge model already yields good performance which can be further improved by employing exact electrostatic quantum-mechanical solute-solvent interaction energies. A larger basis set benefits more significantly from exact over point charge electrostatics, which can be related to differences of the solvent's charge distribution.
Efficient stream distributions in radiative transfer theory
NASA Technical Reports Server (NTRS)
Whitney, C.
1974-01-01
This paper discusses a new, computationally-efficient method for approximating the integro-differential equation of radiative transfer with a finite set of coupled differential equations for discrete streams. The method uses recommended spatial distributions of streams that are quite different from those typically used in that they are based on the symmetry of several regular Platonic solids. To facilitate the use of such distributions, an explicit, one-parameter relationship between the physical radiance and the abstract stream is formulated. The parameter is used to determine the minimum number of streams required in the radiative transfer model. Accuracy and computational efficiency are shown to be served best by choosing a stream distribution that is invariant to a large number of three space rotations. For various values of the above-mentioned parameter, the resulting recommended stream distribution is shown to be more computationally efficient than more conventional stream distributions. Finally, the incorporation of polarization in the stream definition is described.
NASA Astrophysics Data System (ADS)
Tielker, Nicolas; Tomazic, Daniel; Heil, Jochen; Kloss, Thomas; Ehrhart, Sebastian; Güssregen, Stefan; Schmidt, K. Friedemann; Kast, Stefan M.
2016-11-01
We predict cyclohexane-water distribution coefficients (log D 7.4) for drug-like molecules taken from the SAMPL5 blind prediction challenge by the "embedded cluster reference interaction site model" (EC-RISM) integral equation theory. This task involves the coupled problem of predicting both partition coefficients (log P) of neutral species between the solvents and aqueous acidity constants (p K a) in order to account for a change of protonation states. The first issue is addressed by calibrating an EC-RISM-based model for solvation free energies derived from the "Minnesota Solvation Database" (MNSOL) for both water and cyclohexane utilizing a correction based on the partial molar volume, yielding a root mean square error (RMSE) of 2.4 kcal mol-1 for water and 0.8-0.9 kcal mol-1 for cyclohexane depending on the parametrization. The second one is treated by employing on one hand an empirical p K a model (MoKa) and, on the other hand, an EC-RISM-derived regression of published acidity constants (RMSE of 1.5 for a single model covering acids and bases). In total, at most 8 adjustable parameters are necessary (2-3 for each solvent and two for the p K a) for training solvation and acidity models. Applying the final models to the log D 7.4 dataset corresponds to evaluating an independent test set comprising other, composite observables, yielding, for different cyclohexane parametrizations, 2.0-2.1 for the RMSE with the first and 2.2-2.8 with the combined first and second SAMPL5 data set batches. Notably, a pure log P model (assuming neutral species only) performs statistically similarly for these particular compounds. The nature of the approximations and possible perspectives for future developments are discussed.
Tielker, Nicolas; Tomazic, Daniel; Heil, Jochen; Kloss, Thomas; Ehrhart, Sebastian; Güssregen, Stefan; Schmidt, K Friedemann; Kast, Stefan M
2016-11-01
We predict cyclohexane-water distribution coefficients (log D 7.4) for drug-like molecules taken from the SAMPL5 blind prediction challenge by the "embedded cluster reference interaction site model" (EC-RISM) integral equation theory. This task involves the coupled problem of predicting both partition coefficients (log P) of neutral species between the solvents and aqueous acidity constants (pK a) in order to account for a change of protonation states. The first issue is addressed by calibrating an EC-RISM-based model for solvation free energies derived from the "Minnesota Solvation Database" (MNSOL) for both water and cyclohexane utilizing a correction based on the partial molar volume, yielding a root mean square error (RMSE) of 2.4 kcal mol(-1) for water and 0.8-0.9 kcal mol(-1) for cyclohexane depending on the parametrization. The second one is treated by employing on one hand an empirical pK a model (MoKa) and, on the other hand, an EC-RISM-derived regression of published acidity constants (RMSE of 1.5 for a single model covering acids and bases). In total, at most 8 adjustable parameters are necessary (2-3 for each solvent and two for the pK a) for training solvation and acidity models. Applying the final models to the log D 7.4 dataset corresponds to evaluating an independent test set comprising other, composite observables, yielding, for different cyclohexane parametrizations, 2.0-2.1 for the RMSE with the first and 2.2-2.8 with the combined first and second SAMPL5 data set batches. Notably, a pure log P model (assuming neutral species only) performs statistically similarly for these particular compounds. The nature of the approximations and possible perspectives for future developments are discussed.
Hydration Free Energies of Molecular Ions from Theory and Simulation.
Misin, Maksim; Fedorov, Maxim V; Palmer, David S
2016-02-11
We present a theoretical/computational framework for accurate calculation of hydration free energies of ionized molecular species. The method is based on a molecular theory, 3D-RISM, combined with a recently developed pressure correction (PC+). The 3D-RISM/PC+ model can provide ∼3 kcal/mol hydration free energy accuracy for a large variety of ionic compounds, provided that the Galvani potential of water is taken into account. The results are compared with direct atomistic simulations. Several methodological aspects of hydration free energy calculations for charged species are discussed.
Quantum key distribution: theory for application
NASA Astrophysics Data System (ADS)
Lütkenhaus, N.
Quantum key distribution bears the promise to set new standards in secure communication. However, on the way from the theoretical principles to the practical implementation we find many obstacles that need to be taken care of. In this article I show how to obtain a key with a realistic setup such that the security of this key can be proven for an important restricted class of eavesdropping attacks, namely the individual attacks.
Small molecule hydration energy and entropy from 3D-RISM
NASA Astrophysics Data System (ADS)
Johnson, J.; Case, D. A.; Yamazaki, T.; Gusarov, S.; Kovalenko, A.; Luchko, T.
2016-09-01
Implicit solvent models offer an attractive way to estimate the effects of a solvent environment on the properties of small or large solutes without the complications of explicit simulations. One common test of accuracy is to compute the free energy of transfer from gas to liquid for a variety of small molecules, since many of these values have been measured. Studies of the temperature dependence of these values (i.e. solvation enthalpies and entropies) can provide additional insights into the performance of implicit solvent models. Here, we show how to compute temperature derivatives of hydration free energies for the 3D-RISM integral equation approach. We have computed hydration free energies of 1123 small drug-like molecules (both neutral and charged). Temperature derivatives were also used to calculate hydration energies and entropies of 74 of these molecules (both neutral and charged) for which experimental data is available. While direct results have rather poor agreement with experiment, we have found that several previously proposed linear hydration free energy correction schemes give good agreement with experiment. These corrections also provide good agreement for hydration energies and entropies though simple extensions are required in some cases.
Distributed Leadership through the Lens of Activity Theory
ERIC Educational Resources Information Center
Yuen, Jeanne Ho Pau; Victor Chen, Der-Thanq; Ng, David
2016-01-01
Purpose: Using Activity Theory as an interpretive lens to examine the distribution of leadership, this paper shares a case study on how leadership for an ICT project was distributed in a Singapore school. Method: The case study involved observations of 49 meetings and 34 interviews of leaders and the teachers who were involved in the ICT project.…
Product Distribution Theory and Semi-Coordinate Transformations
NASA Technical Reports Server (NTRS)
Airiau, Stephane; Wolpert, David H.
2004-01-01
Product Distribution (PD) theory is a new framework for doing distributed adaptive control of a multiagent system (MAS). We introduce the technique of "coordinate transformations" in PD theory gradient descent. These transformations selectively couple a few agents with each other into "meta-agents". Intuitively, this can be viewed as a generalization of forming binding contracts between those agents. Doing this sacrifices a bit of the distributed nature of the MAS, in that there must now be communication from multiple agents in determining what joint-move is finally implemented However, as we demonstrate in computer experiments, these transformations improve the performance of the MAS.
Product Distribution Theory for Control of Multi-Agent Systems
NASA Technical Reports Server (NTRS)
Lee, Chia Fan; Wolpert, David H.
2004-01-01
Product Distribution (PD) theory is a new framework for controlling Multi-Agent Systems (MAS's). First we review one motivation of PD theory, as the information-theoretic extension of conventional full-rationality game theory to the case of bounded rational agents. In this extension the equilibrium of the game is the optimizer of a Lagrangian of the (probability distribution of) the joint stare of the agents. Accordingly we can consider a team game in which the shared utility is a performance measure of the behavior of the MAS. For such a scenario the game is at equilibrium - the Lagrangian is optimized - when the joint distribution of the agents optimizes the system's expected performance. One common way to find that equilibrium is to have each agent run a reinforcement learning algorithm. Here we investigate the alternative of exploiting PD theory to run gradient descent on the Lagrangian. We present computer experiments validating some of the predictions of PD theory for how best to do that gradient descent. We also demonstrate how PD theory can improve performance even when we are not allowed to rerun the MAS from different initial conditions, a requirement implicit in some previous work.
A geometric theory for Lévy distributions
Eliazar, Iddo
2014-08-15
Lévy distributions are of prime importance in the physical sciences, and their universal emergence is commonly explained by the Generalized Central Limit Theorem (CLT). However, the Generalized CLT is a geometry-less probabilistic result, whereas physical processes usually take place in an embedding space whose spatial geometry is often of substantial significance. In this paper we introduce a model of random effects in random environments which, on the one hand, retains the underlying probabilistic structure of the Generalized CLT and, on the other hand, adds a general and versatile underlying geometric structure. Based on this model we obtain geometry-based counterparts of the Generalized CLT, thus establishing a geometric theory for Lévy distributions. The theory explains the universal emergence of Lévy distributions in physical settings which are well beyond the realm of the Generalized CLT.
Flux theory for Poisson distributed pores with Gaussian permeability.
Salinas, Dino G
2016-01-01
The mean of the solute flux through membrane pores depends on the random distribution and permeability of the pores. Mathematical models including such randomness factors make it possible to obtain statistical parameters for pore characterization. Here, assuming that pores follow a Poisson distribution in the lipid phase and that their permeabilities follow a Gaussian distribution, a mathematical model for solute dynamics is obtained by applying a general result from a previous work regarding any number of different kinds of randomly distributed pores. The new proposed theory is studied using experimental parameters obtained elsewhere, and a method for finding the mean single pore flux rate from liposome flux assays is suggested. This method is useful for pores without requiring studies by patch-clamp in single cells or single-channel recordings. However, it does not apply in the case of ion-selective channels, in which a more complex flux law combining the concentration and electrical gradient is required.
The effectiveness of mean-field theory for avalanche distributions
NASA Astrophysics Data System (ADS)
Lee, Edward; Raju, Archishman; Sethna, James
We explore the mean-field theory of the pseudogap found in avalanche systems with long-range anisotropic interactions using analytical and numerical tools. The pseudogap in the density of low-stability states emerges from the competition between stabilizing interactions between spins in an avalanche and the destabilizing random movement towards the threshold caused by anisotropic couplings. Pazmandi et al. have shown that for the Sherrington-Kirkpatrick model, the pseudogap scales linearly and produces a distribution of avalanche sizes with exponent t=1 in contrast with that predicted from RFIM t=3/2. Lin et al. have argued that the scaling exponent ? of the pseudogap depends on the tail of the distribution of couplings and on non-universal values like the strain rate and the magnitude of the coupling strength. Yet others have argued that the relationship between the pseudogap scaling and the distribution of avalanche sizes is dependent on dynamical details. Despite the theoretical arguments, the class of RFIM mean-field models is surprisingly good at predicting the distribution of avalanche sizes in a variety of different magnetic systems. We investigate these differences with a combination of theory and simulation.
Extracting water and ion distributions from solution x-ray scattering experiments.
Nguyen, Hung T; Pabit, Suzette A; Pollack, Lois; Case, David A
2016-06-07
Small-angle X-ray scattering measurements can provide valuable information about the solvent environment around biomolecules, but it can be difficult to extract solvent-specific information from observed intensity profiles. Intensities are proportional to the square of scattering amplitudes, which are complex quantities. Amplitudes in the forward direction are real, and the contribution from a solute of known structure (and from the waters it excludes) can be estimated from theory; hence, the amplitude arising from the solvent environment can be computed by difference. We have found that this "square root subtraction scheme" can be extended to non-zero q values, out to 0.1 Å(-1) for the systems considered here, since the phases arising from the solute and from the water environment are nearly identical in this angle range. This allows us to extract aspects of the water and ion distributions (beyond their total numbers), by combining experimental data for the complete system with calculations for the solutes. We use this approach to test molecular dynamics and integral-equation (3D-RISM (three-dimensional reference interaction site model)) models for solvent structure around myoglobin, lysozyme, and a 25 base-pair duplex DNA. Comparisons can be made both in Fourier space and in terms of the distribution of interatomic distances in real space. Generally, computed solvent distributions arising from the MD simulations fit experimental data better than those from 3D-RISM, even though the total small-angle X-ray scattering patterns are very similar; this illustrates the potential power of this sort of analysis to guide the development of computational models.
Towards Resource Theory of Coherence in Distributed Scenarios
NASA Astrophysics Data System (ADS)
Streltsov, Alexander; Rana, Swapan; Bera, Manabendra Nath; Lewenstein, Maciej
2017-01-01
The search for a simple description of fundamental physical processes is an important part of quantum theory. One example for such an abstraction can be found in the distance lab paradigm: if two separated parties are connected via a classical channel, it is notoriously difficult to characterize all possible operations these parties can perform. This class of operations is widely known as local operations and classical communication. Surprisingly, the situation becomes comparably simple if the more general class of separable operations is considered, a finding that has been extensively used in quantum information theory for many years. Here, we propose a related approach for the resource theory of quantum coherence, where two distant parties can perform only measurements that do not create coherence and can communicate their outcomes via a classical channel. We call this class local incoherent operations and classical communication. While the characterization of this class is also difficult in general, we show that the larger class of separable incoherent operations has a simple mathematical form, yet still preserves the main features of local incoherent operations and classical communication. We demonstrate the relevance of our approach by applying it to three different tasks: assisted coherence distillation, quantum teleportation, and single-shot quantum state merging. We expect that the results we obtain in this work also transfer to other concepts of coherence that are discussed in recent literature. The approach we present here opens new ways to study the resource theory of coherence in distributed scenarios.
Toward a theory of distributed word expert natural language parsing
NASA Technical Reports Server (NTRS)
Rieger, C.; Small, S.
1981-01-01
An approach to natural language meaning-based parsing in which the unit of linguistic knowledge is the word rather than the rewrite rule is described. In the word expert parser, knowledge about language is distributed across a population of procedural experts, each representing a word of the language, and each an expert at diagnosing that word's intended usage in context. The parser is structured around a coroutine control environment in which the generator-like word experts ask questions and exchange information in coming to collective agreement on sentence meaning. The word expert theory is advanced as a better cognitive model of human language expertise than the traditional rule-based approach. The technical discussion is organized around examples taken from the prototype LISP system which implements parts of the theory.
The ideal free distribution: theory and engineering application.
Quijano, Nicanor; Passino, Kevin M
2007-02-01
We extend the theory of the "ideal free distribution" (IFD) from theoretical ecology by providing methods to analytically find the distribution for a relatively general class of "suitability" functions. We show that the resulting IFD is a Nash equilibrium and an evolutionarily stable strategy (ESS). Moreover, we show that for a certain cost function it is a global optimum point. We introduce the "replicator dynamics" for the IFD and show that we provide an allocation strategy that is guaranteed to achieve the IFD. Finally, we show how this allocation strategy can achieve an IFD for a multizone temperature control problem that corresponds to achieving the maximum uniform temperature on a grid under a multivariable saturation constraint.
NASA Astrophysics Data System (ADS)
Sugita, Masatake; Hirata, Fumio
2016-09-01
A protocol to calculate the binding free energy of a host-guest system is proposed based on the MM/3D-RISM method, taking cyclodextrin derivatives and their ligands as model systems. The protocol involves the procedure to identify the most probable binding mode (MPBM) of receptors and ligands by means of the umbrella sampling method. The binding free energies calculated by the MM/3D-RISM method for the complexes of the seven ligands with the MPBM of the cyclodextrin, and with the fluctuated structures around it, are in agreement with the corresponding experimental data in a semi-quantitative manner. It suggests that the protocol proposed here is promising for predicting the binding affinity of a small ligand to a relatively rigid receptor such as cyclodextrin.
Pion momentum distributions in the nucleon in chiral effective theory
Burkardt, Matthias R.; Hendricks, K. S.; Ji, Cheung Ryong; Melnitchouk, Wally; Thomas, Anthony W.
2013-03-01
We compute the light-cone momentum distributions of pions in the nucleon in chiral effective theory using both pseudovector and pseudoscalar pion--nucleon couplings. For the pseudovector coupling we identify $\\delta$-function contributions associated with end-point singularities arising from the pion-nucleon rainbow diagrams, as well as from pion tadpole diagrams which are not present in the pseudoscalar model. Gauge invariance is demonstrated, to all orders in the pion mass, with the inclusion of Weinberg-Tomozawa couplings involving operator insertions at the $\\pi NN$ vertex. The results pave the way for phenomenological applications of pion cloud models that are manifestly consistent with the chiral symmetry properties of QCD.
Phanich, Jiraphorn; Rungrotmongkol, Thanyada; Sindhikara, Daniel; Phongphanphanee, Saree; Yoshida, Norio; Hirata, Fumio; Kungwan, Nawee; Hannongbua, Supot
2016-01-01
The binding affinity of oseltamivir to the influenza B neuraminidase and to its variants with three single substitutions, E119G, R152K, and D198N, is investigated by the MM/3D-RISM method. The binding affinity or the binding free energy of ligand to receptor was found to be determined by a subtle balance of two major contributions that largely cancel out each other: the ligand-receptor interactions and the dehydration free energy. The theoretical results of the binding affinity of the drug to the mutants reproduced the observed trend in the resistivity, measured by IC50 ; the high-level resistance of E119G and R152K, and the low-level resistance of D198N. For E119G and R152K, reduction of the direct drug-target interaction, especially at the mutated residue, is the main source of high-level oseltamivir resistance. This phenomenon, however, is not found in the D198N strain, which is located in the framework of the active-site.
Beyond Flory theory: Distribution functions for interacting lattice trees
NASA Astrophysics Data System (ADS)
Rosa, Angelo; Everaers, Ralf
2017-01-01
While Flory theories [J. Isaacson and T. C. Lubensky, J. Physique Lett. 41, 469 (1980), 10.1051/jphyslet:019800041019046900; M. Daoud and J. F. Joanny, J. Physique 42, 1359 (1981), 10.1051/jphys:0198100420100135900; A. M. Gutin et al., Macromolecules 26, 1293 (1993), 10.1021/ma00058a016] provide an extremely useful framework for understanding the behavior of interacting, randomly branching polymers, the approach is inherently limited. Here we use a combination of scaling arguments and computer simulations to go beyond a Gaussian description. We analyze distribution functions for a wide variety of quantities characterizing the tree connectivities and conformations for the four different statistical ensembles, which we have studied numerically in [A. Rosa and R. Everaers, J. Phys. A: Math. Theor. 49, 345001 (2016), 10.1088/1751-8113/49/34/345001 and J. Chem. Phys. 145, 164906 (2016), 10.1063/1.4965827]: (a) ideal randomly branching polymers, (b) 2 d and 3 d melts of interacting randomly branching polymers, (c) 3 d self-avoiding trees with annealed connectivity, and (d) 3 d self-avoiding trees with quenched ideal connectivity. In particular, we investigate the distributions (i) pN(n ) of the weight, n , of branches cut from trees of mass N by severing randomly chosen bonds; (ii) pN(l ) of the contour distances, l , between monomers; (iii) pN(r ⃗) of spatial distances, r ⃗, between monomers, and (iv) pN(r ⃗|l ) of the end-to-end distance of paths of length l . Data for different tree sizes superimpose, when expressed as functions of suitably rescaled observables x ⃗=r ⃗/√{
Distribution theory approach to implementing directional acoustic sensors.
Schmidlin, Dean J
2010-01-01
The objective of directional acoustic sensors is to provide high directivity while occupying a small amount of space. An idealized point sensor achieves this objective from a knowledge of the spatial partial derivatives of acoustic pressure at a point in space. Direct measurement of these derivatives is difficult in practice. Consequently, it is expedient to come up with indirect methods. The use of pressure sensors to construct finite-difference approximations is an example of such a method. This paper utilizes the theory of distributions to derive another indirect method for estimating the various spatial partial derivatives of the pressure. This alternate method is then used to construct a multichannel filter which processes the acoustic pressure by mean of three-dimensional integral transforms throughout a 6epsilon-length cube centered at the origin. The output of the multichannel filter is a spatially and temporally filtered version of the pressure at the origin. The temporal filter is a lowpass Gaussian filter whose bandwidth is inversely proportional to epsilon. Finally, the lattice method for numerical multiple integration is utilized to develop a discrete-spatial version of the multichannel filter.
Aono, Shinji; Hosoya, Takashi; Sakaki, Shigeyoshi
2013-05-07
One of the difficulties in application of the usual reference interaction site model self-consistent field (RISM-SCF) method to a highly polarized and bulky system arises from the approximate evaluation of electrostatic potential (ESP) with pure point charges. To improve this ESP evaluation, the ESP near a solute is directly calculated with a solute electronic wavefunction, that distant from a solute is approximately calculated with solute point charges, and they are connected with a switching function. To evaluate the fine solvation structure near the solute by incorporating the long-range solute-solvent Coulombic interaction with low computational cost, we introduced the dual solvent box protocol; one small box with the fine spacing is employed for the first and the second solvation shells and the other large box with the normal spacing is employed for long-range solute-solvent interaction. The levoglucosan formation from phenyl α- and β-d-glucosides under basic conditions is successfully inspected by this 3D-RISM-SCF method at the MP2 and SCS-MP2 levels, though the 1D-RISM-SCF could not be applied to this reaction due to the presence of highly polarized and bulky species. This 3D-RISM-SCF calculation reproduces the experimentally reported higher reactivity of the β-anomer. The 3D-RISM-SCF-calculated activation free energy for the β-anomer is closer to the experimental value than the PCM-calculated one. Interestingly, the solvation effect increases the difference in reactivity between these two anomers. The reason is successfully elucidated with 3D-RISM-SCF-calculated microscopic solvation structure and decomposition analysis of solute-solvent interaction.
M-Estimation for Discrete Data: Asymptotic Distribution Theory and Implications.
1985-11-01
n 860 0029 M-ESTIMATION FOR DISCRETE DATA: ASYMPTOTIC DISTRIBUTION THEORY AND IMPLICATIONS by Douglas G. Simpson 1 Departraent of Statistics... distribution theory of M-estimators especially relevant to discrete data, although Theorem 1 is somewhat broader in scope’. The main results are given in...Extended asymptotic distribution theory Conditions for consistency of an M-estimator can be found in Huber (1964, 1967, 1981). Since the smoothness plays
M-Estimation for Discrete Data. Asymptotic Distribution Theory and Implications.
1985-10-01
DATA: ASYMPTOTIC DISTRIBUTION THEORY AND IMPLICATIONS by 1 Douglas G. Simpson Departr.ient of Statistics University of Illinois Urbana, Illinois...asymptotic distribution theory of M-estimators especially relevant to discrete data, although Theorem 1 is somewhat broader in scope’. The main results are...The version (2.5) c (X9 / - ), where s(a)=9 / + (c) is defined by (2.3), is slightly more convenient. 3. Extended asymptotic distribution theory Conditions
NASA Astrophysics Data System (ADS)
Devanthery, N.; Luzi, G.; Stramondo, S.; Bignami, C.; Pierdicca, N.; Wegmuller, U.; Romaniello, V.; Anniballe, R.; Piscini, A.; Albano, M.; Moro, M.; Crosetto, M.
2016-08-01
The estimate of damage after an earthquake using spaceborne remote sensing data is one of the main application of the change detection methodologies widely discussed in literature. APhoRISM - Advanced PRocedures for volcanIc and Seismic Monitoring is a collaborative European Commission project (FP7-SP ACE- 2013-1) addressing the development of innovative methods, using space and ground sensors to support the management and mitigation of the seismic and the volcanic risk. In this paper a novel approach aimed at damage assessment based on the use of a priori information derived by different sources in a preparedness phase is described and a preliminary validation is shown.
Palmer, David S; Mišin, Maksim; Fedorov, Maxim V; Llinas, Antonio
2015-09-08
We report a method to predict physicochemical properties of druglike molecules using a classical statistical mechanics based solvent model combined with machine learning. The RISM-MOL-INF method introduced here provides an accurate technique to characterize solvation and desolvation processes based on solute-solvent correlation functions computed by the 1D reference interaction site model of the integral equation theory of molecular liquids. These functions can be obtained in a matter of minutes for most small organic and druglike molecules using existing software (RISM-MOL) (Sergiievskyi, V. P.; Hackbusch, W.; Fedorov, M. V. J. Comput. Chem. 2011, 32, 1982-1992). Predictions of caco-2 cell permeability and hydration free energy obtained using the RISM-MOL-INF method are shown to be more accurate than the state-of-the-art tools for benchmark data sets. Due to the importance of solvation and desolvation effects in biological systems, it is anticipated that the RISM-MOL-INF approach will find many applications in biophysical and biomedical property prediction.
On Developing a Theory of Distributed Computing: Summary of Current Research.
1980-09-01
The paradigms of theory can be applied to the problems of concurrency and distribution to yield a rich mathematical theory which will provide a solid framework for practitioner and theoretician alike to use in gaining greater understanding of the exciting and important area of distributed computing . The author is currently engaged in an effort to develop such a theory. This paper summarizes work to date and indicates directions for further research. (Author)
Application of integral equation theory to polyolefin liquids and blends
Curro, J.G.; Weinhold, J.D.
1997-11-01
The ability to model the packing of polymers in melts and blends is important in many polymer applications. One significant application is the development of new polymer blends. It would be exceedingly helpful to the materials chemist if molecular modeling could be employed to predict the thermodynamics and phase behavior of hypothetical polymer alloys before embarking on a time consuming and expensive synthesis program. The well known Flory-Huggins theory has been remarkably successful in describing many aspects of polymer mixing from a qualitative point of view. This theory is known, however, to suffer from several deficiencies which can be traceable to the fact that: (1) it is a lattice model requiring both monomer components to have the same volume; and (2) a mean field or random mixing approximation is made which effectively ignores chain connectivity. Because of these limitations the Flory-Huggins theory does not include packing effects and cannot be used to make quantitative molecular engineering calculations. Recently Curro and Schweizer developed a new approach for treating polymer liquids and mixtures which the authors call PRISM theory. This is an extension to polymers of the Reference Interaction Site Model (RISM Theory) developed by Chandler and Andersen to describe the statistical mechanics of small molecule liquids. The PRISM theory is a continuous space description of a polymer liquid, which includes chain connectivity and nonrandom mixing effects in a computationally tractable manner. The primary output from PRISM calculations is the average structure or packing of the amorphous liquid given by the radial distribution function denoted as g(r). This radial distribution function is employed to deduce thermodynamic or structural properties of interest. Here, the authors describe the theoretical approach and demonstrate its application to polyethylene, isotactic polypropylene, syndiotactic polypropylene, and polyisobutylene liquids and blends.
Singularity in the Laboratory Frame Angular Distribution Derived in Two-Body Scattering Theory
ERIC Educational Resources Information Center
Dick, Frank; Norbury, John W.
2009-01-01
The laboratory (lab) frame angular distribution derived in two-body scattering theory exhibits a singularity at the maximum lab scattering angle. The singularity appears in the kinematic factor that transforms the centre of momentum (cm) angular distribution to the lab angular distribution. We show that it is caused in the transformation by the…
Synthesising Theory and Practice: Distributed Leadership in Higher Education
ERIC Educational Resources Information Center
Jones, Sandra; Harvey, Marina; Lefoe, Geraldine; Ryland, Kevin
2014-01-01
Changes facing higher education from increased government, student and community demands are resulting in a greater focus on leadership within universities. Attempts to adapt to higher education theory that underpins leadership in other sectors have been criticised for failing to recognise its unique role in the development of creative and…
Munaò, Gianmarco Costa, Dino; Caccamo, Carlo; Gámez, Francisco; Giacometti, Achille
2015-06-14
We investigate thermodynamic properties of anisotropic colloidal dumbbells in the frameworks provided by the Reference Interaction Site Model (RISM) theory and an Optimized Perturbation Theory (OPT), this latter based on a fourth-order high-temperature perturbative expansion of the free energy, recently generalized to molecular fluids. Our model is constituted by two identical tangent hard spheres surrounded by square-well attractions with same widths and progressively different depths. Gas-liquid coexistence curves are obtained by predicting pressures, free energies, and chemical potentials. In comparison with previous simulation results, RISM and OPT agree in reproducing the progressive reduction of the gas-liquid phase separation as the anisotropy of the interaction potential becomes more pronounced; in particular, the RISM theory provides reasonable predictions for all coexistence curves, bar the strong anisotropy regime, whereas OPT performs generally less well. Both theories predict a linear dependence of the critical temperature on the interaction strength, reproducing in this way the mean-field behavior observed in simulations; the critical density—that drastically drops as the anisotropy increases—turns to be less accurate. Our results appear as a robust benchmark for further theoretical studies, in support to the simulation approach, of self-assembly in model colloidal systems.
Three-Dimensional Molecular Theory of Solvation Coupled with Molecular Dynamics in Amber
Luchko, T.; Simmerling, C.; Gusarov, S.; Roe, D.R., Case, D.A.; Tuszynski, J.; Kovalenko, A.
2010-02-01
We present the three-dimensional molecular theory of solvation (also known as 3D-RISM) coupled with molecular dynamics (MD) simulation by contracting solvent degrees of freedom, accelerated by extrapolating solvent-induced forces and applying them in large multiple time steps (up to 20 fs) to enable simulation of large biomolecules. The method has been implemented in the Amber molecular modeling package and is illustrated here on alanine-dipeptide and protein-G.
Towards a Theory of Distributed Instruction in Creative Arts Education
ERIC Educational Resources Information Center
Rosenfeld Halverson, Erica; Lowenhaupt, Rebecca; Kalaitzidis, T. J.
2015-01-01
This article examines how arts-based informal learning spaces engage young people at the intersection of creativity and technology. We conducted case studies of four youth media arts organizations to understand how teaching is defined and realized in these contexts. We find that teaching is a distributed act that sits at the intersection of…
A model of a linear synchronous motor based on distribution theory
NASA Astrophysics Data System (ADS)
Trapanese, Marco
2012-04-01
The fundamental idea of this paper is to use the distribution theory to analyze linear machines in order to include in the mathematical model both ideal and non ideal features. This paper shows how distribution theory can be used to establish a mathematical model able to describe both the ordinary working condition of a Linear Synchronous Motor (LSM) as well the role of the unavoidable irregularities and non ideal features.
Measurement of continuous distributions of ventilation-perfusion ratios - Theory
NASA Technical Reports Server (NTRS)
Wagner, P. D.; Saltzman, H. A.; West, J. B.
1974-01-01
The resolution of the technique considered is sufficient to describe smooth distributions containing blood flow to unventilated regions (shunt), ventilation to unperfused regions (dead space), and up to three additional modes over the range of finite ventilation-perfusion ratios. In particular, areas whose ventilation-perfusion ratios are low can be separated from unventilated regions and those whose ventilation-perfusion ratios are high can similarly be distinguished from unperfused areas.
General theory of airfoil sections having arbitrary shape or pressure distribution
NASA Technical Reports Server (NTRS)
Allen, H Julian
1945-01-01
In this report a theory of thin airfoils of small camber is developed which permits either the velocity distribution corresponding to a given airfoil shape, or the airfoil shape corresponding to a given velocity distribution to be calculated. The procedures to be employed in these calculations are outlined and illustrated with suitable examples.
ERIC Educational Resources Information Center
Woods, Carol M.; Thissen, David
2006-01-01
The purpose of this paper is to introduce a new method for fitting item response theory models with the latent population distribution estimated from the data using splines. A spline-based density estimation system provides a flexible alternative to existing procedures that use a normal distribution, or a different functional form, for the…
Two-dimensional fluorescence intensity distribution analysis: theory and applications.
Kask, P; Palo, K; Fay, N; Brand, L; Mets, U; Ullmann, D; Jungmann, J; Pschorr, J; Gall, K
2000-04-01
A method of sample analysis is presented which is based on fitting a joint distribution of photon count numbers. In experiments, fluorescence from a microscopic volume containing a fluctuating number of molecules is monitored by two detectors, using a confocal microscope. The two detectors may have different polarizational or spectral responses. Concentrations of fluorescent species together with two specific brightness values per species are determined. The two-dimensional fluorescence intensity distribution analysis (2D-FIDA), if used with a polarization cube, is a tool that is able to distinguish fluorescent species with different specific polarization ratios. As an example of polarization studies by 2D-FIDA, binding of 5'-(6-carboxytetramethylrhodamine) (TAMRA)-labeled theophylline to an anti-theophylline antibody has been studied. Alternatively, if two-color equipment is used, 2D-FIDA can determine concentrations and specific brightness values of fluorescent species corresponding to individual labels alone and their complex. As an example of two-color 2D-FIDA, binding of TAMRA-labeled somatostatin-14 to the human type-2 high-affinity somatostatin receptors present in stained vesicles has been studied. The presented method is unusually accurate among fluorescence fluctuation methods. It is well suited for monitoring a variety of molecular interactions, including receptors and ligands or antibodies and antigens.
The distributional zeta-function in disordered field theory
NASA Astrophysics Data System (ADS)
Svaiter, B. F.; Svaiter, N. F.
2016-09-01
In this paper, we present a new mathematical rigorous technique for computing the average free energy of a disordered system with quenched randomness, using the replicas. The basic tool of this technique is a distributional zeta-function, a complex function whose derivative at the origin yields the average free energy of the system as the sum of two contributions: the first one is a series in which all the integer moments of the partition function of the model contribute; the second one, which cannot be written as a series of the integer moments, can be made as small as desired. This result supports the use of integer moments of the partition function, computed via replicas, for expressing the average free energy of the system. One advantage of the proposed formalism is that it does not require the understanding of the properties of the permutation group when the number of replicas goes to zero. Moreover, the symmetry is broken using the saddle-point equations of the model. As an application for the distributional zeta-function technique, we obtain the average free energy of the disordered λφ4 model defined in a d-dimensional Euclidean space.
Distribution theory for Schrödinger’s integral equation
Lange, Rutger-Jan
2015-12-15
Much of the literature on point interactions in quantum mechanics has focused on the differential form of Schrödinger’s equation. This paper, in contrast, investigates the integral form of Schrödinger’s equation. While both forms are known to be equivalent for smooth potentials, this is not true for distributional potentials. Here, we assume that the potential is given by a distribution defined on the space of discontinuous test functions. First, by using Schrödinger’s integral equation, we confirm a seminal result by Kurasov, which was originally obtained in the context of Schrödinger’s differential equation. This hints at a possible deeper connection between both forms of the equation. We also sketch a generalisation of Kurasov’s [J. Math. Anal. Appl. 201(1), 297–323 (1996)] result to hypersurfaces. Second, we derive a new closed-form solution to Schrödinger’s integral equation with a delta prime potential. This potential has attracted considerable attention, including some controversy. Interestingly, the derived propagator satisfies boundary conditions that were previously derived using Schrödinger’s differential equation. Third, we derive boundary conditions for “super-singular” potentials given by higher-order derivatives of the delta potential. These boundary conditions cannot be incorporated into the normal framework of self-adjoint extensions. We show that the boundary conditions depend on the energy of the solution and that probability is conserved. This paper thereby confirms several seminal results and derives some new ones. In sum, it shows that Schrödinger’s integral equation is a viable tool for studying singular interactions in quantum mechanics.
Distribution theory for Schrödinger's integral equation
NASA Astrophysics Data System (ADS)
Lange, Rutger-Jan
2015-12-01
Much of the literature on point interactions in quantum mechanics has focused on the differential form of Schrödinger's equation. This paper, in contrast, investigates the integral form of Schrödinger's equation. While both forms are known to be equivalent for smooth potentials, this is not true for distributional potentials. Here, we assume that the potential is given by a distribution defined on the space of discontinuous test functions. First, by using Schrödinger's integral equation, we confirm a seminal result by Kurasov, which was originally obtained in the context of Schrödinger's differential equation. This hints at a possible deeper connection between both forms of the equation. We also sketch a generalisation of Kurasov's [J. Math. Anal. Appl. 201(1), 297-323 (1996)] result to hypersurfaces. Second, we derive a new closed-form solution to Schrödinger's integral equation with a delta prime potential. This potential has attracted considerable attention, including some controversy. Interestingly, the derived propagator satisfies boundary conditions that were previously derived using Schrödinger's differential equation. Third, we derive boundary conditions for "super-singular" potentials given by higher-order derivatives of the delta potential. These boundary conditions cannot be incorporated into the normal framework of self-adjoint extensions. We show that the boundary conditions depend on the energy of the solution and that probability is conserved. This paper thereby confirms several seminal results and derives some new ones. In sum, it shows that Schrödinger's integral equation is a viable tool for studying singular interactions in quantum mechanics.
Evaluating Ecohydrological Theories of Woody Root Distribution in the Kalahari
Bhattachan, Abinash; Tatlhego, Mokganedi; Dintwe, Kebonye; O'Donnell, Frances; Caylor, Kelly K.; Okin, Gregory S.; Perrot, Danielle O.; Ringrose, Susan; D'Odorico, Paolo
2012-01-01
The contribution of savannas to global carbon storage is poorly understood, in part due to lack of knowledge of the amount of belowground biomass. In these ecosystems, the coexistence of woody and herbaceous life forms is often explained on the basis of belowground interactions among roots. However, the distribution of root biomass in savannas has seldom been investigated, and the dependence of root biomass on rainfall regime remains unclear, particularly for woody plants. Here we investigate patterns of belowground woody biomass along a rainfall gradient in the Kalahari of southern Africa, a region with consistent sandy soils. We test the hypotheses that (1) the root depth increases with mean annual precipitation (root optimality and plant hydrotropism hypothesis), and (2) the root-to-shoot ratio increases with decreasing mean annual rainfall (functional equilibrium hypothesis). Both hypotheses have been previously assessed for herbaceous vegetation using global root data sets. Our data do not support these hypotheses for the case of woody plants in savannas. We find that in the Kalahari, the root profiles of woody plants do not become deeper with increasing mean annual precipitation, whereas the root-to-shoot ratios decrease along a gradient of increasing aridity. PMID:22470506
Issues in biomedical statistics: comparing means under normal distribution theory.
Ludbrook, J
1995-04-01
The test used most commonly in biomedical research to compare means when measurements have been made on a continuous scale is Student's t-test, followed closely by various forms of analysis of variance. These tests require that defined populations have been randomly sampled, but there are other assumptions about populations and samples that must be satisfied. These include: (i) normality of the population distributions; (ii) equal variance in those normal populations; and (iii) statistical independence of the samples. This review offers advice to investigators on how to recognize breaches of the assumptions of normality and equality of variance, and how to deal with them by modifying the usual t-test or by transforming the experimental data. The sample-size also has an important bearing on statistical inferences: (i) if it is too small, the risk of Type II error is inflated; and (ii) inequality of sample size exaggerates the effects of inequality of variance. The assumption of independence is breached if repeated measurements are made serially rather than in random order, but adjustments to analysis of variance can be made to correct for the inflated risk of Type I error. The review also considers the problem of making multiple comparisons of means, and recommends solutions.
Independent test assessment using the extreme value distribution theory.
Almeida, Marcio; Blondell, Lucy; Peralta, Juan M; Kent, Jack W; Jun, Goo; Teslovich, Tanya M; Fuchsberger, Christian; Wood, Andrew R; Manning, Alisa K; Frayling, Timothy M; Cingolani, Pablo E; Sladek, Robert; Dyer, Thomas D; Abecasis, Goncalo; Duggirala, Ravindranath; Blangero, John
2016-01-01
The new generation of whole genome sequencing platforms offers great possibilities and challenges for dissecting the genetic basis of complex traits. With a very high number of sequence variants, a naïve multiple hypothesis threshold correction hinders the identification of reliable associations by the overreduction of statistical power. In this report, we examine 2 alternative approaches to improve the statistical power of a whole genome association study to detect reliable genetic associations. The approaches were tested using the Genetic Analysis Workshop 19 (GAW19) whole genome sequencing data. The first tested method estimates the real number of effective independent tests actually being performed in whole genome association project by the use of an extreme value distribution and a set of phenotype simulations. Given the familiar nature of the GAW19 data and the finite number of pedigree founders in the sample, the number of correlations between genotypes is greater than in a set of unrelated samples. Using our procedure, we estimate that the effective number represents only 15 % of the total number of independent tests performed. However, even using this corrected significance threshold, no genome-wide significant association could be detected for systolic and diastolic blood pressure traits. The second approach implements a biological relevance-driven hypothesis tested by exploiting prior computational predictions on the effect of nonsynonymous genetic variants detected in a whole genome sequencing association study. This guided testing approach was able to identify 2 promising single-nucleotide polymorphisms (SNPs), 1 for each trait, targeting biologically relevant genes that could help shed light on the genesis of the human hypertension. The first gene, PFH14, associated with systolic blood pressure, interacts directly with genes involved in calcium-channel formation and the second gene, MAP4, encodes a microtubule-associated protein and had already been
Zhou, Yun Pollak, Eli; Miret-Artés, Salvador
2014-01-14
A second order classical perturbation theory is developed and applied to elastic atom corrugated surface scattering. The resulting theory accounts for experimentally observed asymmetry in the final angular distributions. These include qualitative features, such as reduction of the asymmetry in the intensity of the rainbow peaks with increased incidence energy as well as the asymmetry in the location of the rainbow peaks with respect to the specular scattering angle. The theory is especially applicable to “soft” corrugated potentials. Expressions for the angular distribution are derived for the exponential repulsive and Morse potential models. The theory is implemented numerically to a simplified model of the scattering of an Ar atom from a LiF(100) surface.
The force distribution probability function for simple fluids by density functional theory.
Rickayzen, G; Heyes, D M
2013-02-28
Classical density functional theory (DFT) is used to derive a formula for the probability density distribution function, P(F), and probability distribution function, W(F), for simple fluids, where F is the net force on a particle. The final formula for P(F) ∝ exp(-AF(2)), where A depends on the fluid density, the temperature, and the Fourier transform of the pair potential. The form of the DFT theory used is only applicable to bounded potential fluids. When combined with the hypernetted chain closure of the Ornstein-Zernike equation, the DFT theory for W(F) agrees with molecular dynamics computer simulations for the Gaussian and bounded soft sphere at high density. The Gaussian form for P(F) is still accurate at lower densities (but not too low density) for the two potentials, but with a smaller value for the constant, A, than that predicted by the DFT theory.
West, R.; Tsang, Leung; Winebrenner, D.P. )
1993-03-01
Dense medium radiative transfer theory is applied to a three-layer model consisting of two scattering layers overlying a homogeneous half space with a size distribution of particles in each layer. A model with a distribution of sizes gives quite different results than those obtained from a model with a single size. The size distribution is especially important in the low frequency limit when scattering is strongly dependent on particle size. The size distribution and absorption characteristics also affect the extinction behavior as a function of fractional volume. Theoretical results are also compared with experimental data. The sizes, permittivities, and densities used in the numerical illustrations are typical values for snow.
Lemons, D.S.; Feldman, W.C.
1983-09-01
A theoretical model of suprathermal halo or strahl solar wind electrons, including both binary collisions and conservative force fields, is proposed. From this model we derive the collisionally modified electron pitch angle distribution and compare it with relevant measurements made in the solar wind at 1 AU by using the Los Alamos IMP 8 plasma analyzer. Although the collisionally modified distribution is more isotropic than that predicted by simple exospheric theory, it is not isotropic enough to describe the measurements.
The Distribution of the Product Explains Normal Theory Mediation Confidence Interval Estimation.
Kisbu-Sakarya, Yasemin; MacKinnon, David P; Miočević, Milica
2014-05-01
The distribution of the product has several useful applications. One of these applications is its use to form confidence intervals for the indirect effect as the product of 2 regression coefficients. The purpose of this article is to investigate how the moments of the distribution of the product explain normal theory mediation confidence interval coverage and imbalance. Values of the critical ratio for each random variable are used to demonstrate how the moments of the distribution of the product change across values of the critical ratio observed in research studies. Results of the simulation study showed that as skewness in absolute value increases, coverage decreases. And as skewness in absolute value and kurtosis increases, imbalance increases. The difference between testing the significance of the indirect effect using the normal theory versus the asymmetric distribution of the product is further illustrated with a real data example. This article is the first study to show the direct link between the distribution of the product and indirect effect confidence intervals and clarifies the results of previous simulation studies by showing why normal theory confidence intervals for indirect effects are often less accurate than those obtained from the asymmetric distribution of the product or from resampling methods.
Systematic analysis of transverse momentum distribution and non-extensive thermodynamics theory
Sena, I.; Deppman, A.
2013-03-25
A systematic analysis of transverse momentum distribution of hadrons produced in ultrarelativistic p+p and A+A collisions is presented. We investigate the effective temperature and the entropic parameter from the non-extensive thermodynamic theory of strong interaction. We conclude that the existence of a limiting effective temperature and of a limiting entropic parameter is in accordance with experimental data.
Do Hegemons Distribute Private Goods?: A Test of Power-Transition Theory
ERIC Educational Resources Information Center
Bussmann, Margit; Oneal, John R.
2007-01-01
According to power-transition theory, war is most likely when the leading state is challenged by a rapidly growing, dissatisfied rival. Challengers are said to be dissatisfied because the hegemon manages the status quo for its own benefit, rewarding its allies and penalizing rivals. We assess the leading state's ability to distribute the private…
The Feynman integrand as a white noise distribution beyond perturbation theory
Grothaus, Martin; Vogel, Anna
2008-06-18
In this note the concepts of path integrals and techniques how to construct them are presented. Here we concentrate on a White Noise approach. Combining White Noise techniques with a generalized time-dependent Doss' formula Feynman integrands are constructed as white noise distributions beyond perturbation theory.
Information theory lateral density distribution for Earth inferred from global gravity field
NASA Technical Reports Server (NTRS)
Rubincam, D. P.
1981-01-01
Information Theory Inference, better known as the Maximum Entropy Method, was used to infer the lateral density distribution inside the Earth. The approach assumed that the Earth consists of indistinguishable Maxwell-Boltzmann particles populating infinitesimal volume elements, and followed the standard methods of statistical mechanics (maximizing the entropy function). The GEM 10B spherical harmonic gravity field coefficients, complete to degree and order 36, were used as constraints on the lateral density distribution. The spherically symmetric part of the density distribution was assumed to be known. The lateral density variation was assumed to be small compared to the spherically symmetric part. The resulting information theory density distribution for the cases of no crust removed, 30 km of compensated crust removed, and 30 km of uncompensated crust removed all gave broad density anomalies extending deep into the mantle, but with the density contrasts being the greatest towards the surface (typically + or 0.004 g cm 3 in the first two cases and + or - 0.04 g cm 3 in the third). None of the density distributions resemble classical organized convection cells. The information theory approach may have use in choosing Standard Earth Models, but, the inclusion of seismic data into the approach appears difficult.
An approximation theory for the identification of nonlinear distributed parameter systems
NASA Technical Reports Server (NTRS)
Banks, H. T.; Reich, Simeon; Rosen, I. G.
1990-01-01
An abstract approximation framework for the identification of nonlinear distributed parameter systems is developed. Inverse problems for nonlinear systems governed by strongly maximal monotone operators (satisfying a mild continuous dependence condition with respect to the unknown parameters to be identified) are treated. Convergence of Galerkin approximations and the corresponding solutions of finite dimensional approximating identification problems to a solution of the original finite dimensional identification problem is demonstrated using the theory of nonlinear evolution systems and a nonlinear analog of the Trotter-Kato appproximation result for semigroups of bounded linear operators. The nonlinear theory developed here is shown to subsume an existing linear theory as a special case. It is also shown to be applicable to a broad class of nonlinear elliptic operators and the corresponding nonlinear parabolic partial differential equations to which they lead. An application of the theory to a quasilinear model for heat conduction or mass transfer is discussed.
Operator counting and eigenvalue distributions for 3D supersymmetric gauge theories
NASA Astrophysics Data System (ADS)
Gulotta, Daniel R.; Herzog, Christopher P.; Pufu, Silviu S.
2011-11-01
We give further support for our conjecture relating eigenvalue distributions of the Kapustin-Willett-Yaakov matrix model in the large N limit to numbers of operators in the chiral ring of the corresponding supersymmetric three-dimensional gauge theory. We show that the relation holds for non-critical R-charges and for examples with mathcal{N} = {2} instead of mathcal{N} = {3} supersymmetry where the bifundamental matter fields are nonchiral. We prove that, for non-critical R-charges, the conjecture is equivalent to a relation between the free energy of the gauge theory on a three sphere and the volume of a Sasaki manifold that is part of the moduli space of the gauge theory. We also investigate the consequences of our conjecture for chiral theories where the matrix model is not well understood.
An approximation theory for the identification of nonlinear distributed parameter systems
NASA Technical Reports Server (NTRS)
Banks, H. T.; Reich, Simeon; Rosen, I. G.
1988-01-01
An abstract approximation framework for the identification of nonlinear distributed parameter systems is developed. Inverse problems for nonlinear systems governed by strongly maximal monotone operators (satisfying a mild continuous dependence condition with respect to the unknown parameters to be identified) are treated. Convergence of Galerkin approximations and the corresponding solutions of finite dimensional approximating identification problems to a solution of the original finite dimensional identification problem is demonstrated using the theory of nonlinear evolution systems and a nonlinear analog of the Trotter-Kato approximation result for semigroups of bounded linear operators. The nonlinear theory developed here is shown to subsume an existing linear theory as a special case. It is also shown to be applicable to a broad class of nonlinear elliptic operators and the corresponding nonlinear parabolic partial differential equations to which they lead. An application of the theory to a quasilinear model for heat conduction or mass transfer is discussed.
Axisymmetric Distributions of Thick Circular Plate in a Modified Couple Stress Theory
NASA Astrophysics Data System (ADS)
Kumar, Rajneesh; Marin, Marin; Abbas, Ibrahim A.
2015-07-01
In this paper, the two-dimensional axisymmetric distributions of thick circular plate in modified couple stress theory with heat and mass diffusive sources is investigated. The problem is considered in the context of the theories of thermodiffusion elastic solid with one and two relaxation time developed by Sherief et al. [Int. J. Eng. Sci. 42, 591 (2004)] and Kumar and Kansal [Int. J. Solid Struct. 45, 5890 (2008)] by using Laplace and Hankel transforms technique. The displacements, stress components, temperature change and chemical potential are obtained in transformed domain. Particular cases of interest are also deduced.
On the theory of Ostwald ripening: formation of the universal distribution
NASA Astrophysics Data System (ADS)
Alexandrov, D. V.
2015-01-01
A theoretical description of the final stage of Ostwald ripening given by Lifshitz and Slyozov (LS) predicts that after long times the distribution of particles over sizes tends to a universal form. A qualitative behavior of their theory has been confirmed, but experimental particle size distributions are more broad and squat than the LS asymptotic solution. The origin of discrepancies between the theory and experimental data is caused by the relaxation of solutions from the early to late stages of Ostwald ripening. In other words, the initial conditions at the ripening stage lead to the formation of a transition region near the blocking point of the LS theory and completely determine the distribution function. A new theoretical approach of the present analysis based on the Slezov theory (Slezov 1978 Formation of the universal distribution function in the dimension space for new-phase particles in the diffusive decomposition of the supersaturated solid solution J. Phys. Chem. Solids 39 367-74 Slezov 2009 Kinetics of First-Order Phase Transitions (Weinheim: Wiley, VCH)) focuses on a relaxation dynamics of analytical solutions from the early stage of Ostwald ripening to its concluding state, which is described by the LS asymptotic regime. An algebraic equation for the boundaries of a transition layer independent of all material parameters is derived. A time-dependent function \\varepsilon (τ ) responsible for the evolution of solutions at the ripening stage is found. The distribution function obtained is more broad and flat than the LS asymptotic solution. The particle radius, supersaturation and number density as functions of time are determined. The analytical solutions obtained are in good agreement with experimental data.
Omelyan, Igor E-mail: omelyan@icmp.lviv.ua; Kovalenko, Andriy
2013-12-28
We develop efficient handling of solvation forces in the multiscale method of multiple time step molecular dynamics (MTS-MD) of a biomolecule steered by the solvation free energy (effective solvation forces) obtained from the 3D-RISM-KH molecular theory of solvation (three-dimensional reference interaction site model complemented with the Kovalenko-Hirata closure approximation). To reduce the computational expenses, we calculate the effective solvation forces acting on the biomolecule by using advanced solvation force extrapolation (ASFE) at inner time steps while converging the 3D-RISM-KH integral equations only at large outer time steps. The idea of ASFE consists in developing a discrete non-Eckart rotational transformation of atomic coordinates that minimizes the distances between the atomic positions of the biomolecule at different time moments. The effective solvation forces for the biomolecule in a current conformation at an inner time step are then extrapolated in the transformed subspace of those at outer time steps by using a modified least square fit approach applied to a relatively small number of the best force-coordinate pairs. The latter are selected from an extended set collecting the effective solvation forces obtained from 3D-RISM-KH at outer time steps over a broad time interval. The MTS-MD integration with effective solvation forces obtained by converging 3D-RISM-KH at outer time steps and applying ASFE at inner time steps is stabilized by employing the optimized isokinetic Nosé-Hoover chain (OIN) ensemble. Compared to the previous extrapolation schemes used in combination with the Langevin thermostat, the ASFE approach substantially improves the accuracy of evaluation of effective solvation forces and in combination with the OIN thermostat enables a dramatic increase of outer time steps. We demonstrate on a fully flexible model of alanine dipeptide in aqueous solution that the MTS-MD/OIN/ASFE/3D-RISM-KH multiscale method of molecular dynamics
NASA Astrophysics Data System (ADS)
Omelyan, Igor; Kovalenko, Andriy
2013-12-01
We develop efficient handling of solvation forces in the multiscale method of multiple time step molecular dynamics (MTS-MD) of a biomolecule steered by the solvation free energy (effective solvation forces) obtained from the 3D-RISM-KH molecular theory of solvation (three-dimensional reference interaction site model complemented with the Kovalenko-Hirata closure approximation). To reduce the computational expenses, we calculate the effective solvation forces acting on the biomolecule by using advanced solvation force extrapolation (ASFE) at inner time steps while converging the 3D-RISM-KH integral equations only at large outer time steps. The idea of ASFE consists in developing a discrete non-Eckart rotational transformation of atomic coordinates that minimizes the distances between the atomic positions of the biomolecule at different time moments. The effective solvation forces for the biomolecule in a current conformation at an inner time step are then extrapolated in the transformed subspace of those at outer time steps by using a modified least square fit approach applied to a relatively small number of the best force-coordinate pairs. The latter are selected from an extended set collecting the effective solvation forces obtained from 3D-RISM-KH at outer time steps over a broad time interval. The MTS-MD integration with effective solvation forces obtained by converging 3D-RISM-KH at outer time steps and applying ASFE at inner time steps is stabilized by employing the optimized isokinetic Nosé-Hoover chain (OIN) ensemble. Compared to the previous extrapolation schemes used in combination with the Langevin thermostat, the ASFE approach substantially improves the accuracy of evaluation of effective solvation forces and in combination with the OIN thermostat enables a dramatic increase of outer time steps. We demonstrate on a fully flexible model of alanine dipeptide in aqueous solution that the MTS-MD/OIN/ASFE/3D-RISM-KH multiscale method of molecular dynamics
Parameter estimation in nonlinear distributed systems - Approximation theory and convergence results
NASA Technical Reports Server (NTRS)
Banks, H. T.; Reich, Simeon; Rosen, I. G.
1988-01-01
An abstract approximation framework and convergence theory is described for Galerkin approximations applied to inverse problems involving nonlinear distributed parameter systems. Parameter estimation problems are considered and formulated as the minimization of a least-squares-like performance index over a compact admissible parameter set subject to state constraints given by an inhomogeneous nonlinear distributed system. The theory applies to systems whose dynamics can be described by either time-independent or nonstationary strongly maximal monotonic operators defined on a reflexive Banach space which is densely and continuously embedded in a Hilbert space. It is demonstrated that if readily verifiable conditions on the system's dependence on the unknown parameters are satisfied, and the usual Galerkin approximation assumption holds, then solutions to the approximating problems exist and approximate a solution to the original infinite-dimensional identification problem.
Gormley, Denise K; Colella, Christine; Shell, Dustin L
2012-01-01
Learning online requires self-regulation, intrinsic motivation, and independence. Building an online classroom environment that fosters the development of these behaviors for students is key to their success. Use of ARCS (attention, relevance, confidence, satisfaction) Motivational Theory and distributed scaffolding can assist faculty in developing intentional support to help the online student achieve learning outcomes. The authors discuss development of teaching strategies in online, distance learning courses that will enhance student motivation and learning outcomes.
NASA Technical Reports Server (NTRS)
Medan, R. T.; Ray, K. S.
1974-01-01
A description of and users manual are presented for a U.S.A. FORTRAN 4 computer program which evaluates spanwise and chordwise loading distributions, lift coefficient, pitching moment coefficient, and other stability derivatives for thin wings in linearized, steady, subsonic flow. The program is based on a kernel function method lifting surface theory and is applicable to a large class of planforms including asymmetrical ones and ones with mixed straight and curved edges.
A new probability distribution model of turbulent irradiance based on Born perturbation theory
NASA Astrophysics Data System (ADS)
Wang, Hongxing; Liu, Min; Hu, Hao; Wang, Qian; Liu, Xiguo
2010-10-01
The subject of the PDF (Probability Density Function) of the irradiance fluctuations in a turbulent atmosphere is still unsettled. Theory reliably describes the behavior in the weak turbulence regime, but theoretical description in the strong and whole turbulence regimes are still controversial. Based on Born perturbation theory, the physical manifestations and correlations of three typical PDF models (Rice-Nakagami, exponential-Bessel and negative-exponential distribution) were theoretically analyzed. It is shown that these models can be derived by separately making circular-Gaussian, strong-turbulence and strong-turbulence-circular-Gaussian approximations in Born perturbation theory, which denies the viewpoint that the Rice-Nakagami model is only applicable in the extremely weak turbulence regime and provides theoretical arguments for choosing rational models in practical applications. In addition, a common shortcoming of the three models is that they are all approximations. A new model, called the Maclaurin-spread distribution, is proposed without any approximation except for assuming the correlation coefficient to be zero. So, it is considered that the new model can exactly reflect the Born perturbation theory. Simulated results prove the accuracy of this new model.
Health as normal function: a weak link in Daniels's theory of just health distribution.
Krag, Erik
2014-10-01
Drawing on Christopher Boorse's Biostatistical Theory (BST), Norman Daniels contends that a genuine health need is one which is necessary to restore normal functioning - a supposedly objective notion which he believes can be read from the natural world without reference to potentially controversial normative categories. But despite his claims to the contrary, this conception of health harbors arbitrary evaluative judgments which make room for intractable disagreement as to which conditions should count as genuine health needs and therefore which needs should be met. I begin by offering a brief summary of Boorse's BST, the theory to which Daniels appeals for providing the conception of health as normal functioning upon which his overall distributive scheme rests. Next, I consider what I call practical objections to Daniels's use of Boorse's theory. Finally I recount Elseljin Kingma's theoretical objection to Boorse's BST and discuss its impact on Daniels's overall theory. Though I conclude that Boorse's view, so weakened, will no longer be able to sustain the judgments which Daniels's theory uses it to reach, in the end, I offer Daniels an olive branch by briefly sketching an alternative strategy for reaching suitably objective conclusions regarding the health and/or disease status of various conditions.
Amano, Ken-Ichi; Liang, Yunfeng; Miyazawa, Keisuke; Kobayashi, Kazuya; Hashimoto, Kota; Fukami, Kazuhiro; Nishi, Naoya; Sakka, Tetsuo; Onishi, Hiroshi; Fukuma, Takeshi
2016-06-21
Atomic force microscopy (AFM) in liquids can measure a force curve between a probe and a buried substrate. The shape of the measured force curve is related to hydration structure on the substrate. However, until now, there has been no practical theory that can transform the force curve into the hydration structure, because treatment of the liquid confined between the probe and the substrate is a difficult problem. Here, we propose a robust and practical transform theory, which can generate the number density distribution of solvent molecules on a substrate from the force curve. As an example, we analyzed a force curve measured by using our high-resolution AFM with a newly fabricated ultrashort cantilever. It is demonstrated that the hydration structure on muscovite mica (001) surface can be reproduced from the force curve by using the transform theory. The transform theory will enhance AFM's ability and support structural analyses of solid/liquid interfaces. By using the transform theory, the effective diameter of a real probe apex is also obtained. This result will be important for designing a model probe of molecular scale simulations.
Optimization of pressure gauge locations for water distribution systems using entropy theory.
Yoo, Do Guen; Chang, Dong Eil; Jun, Hwandon; Kim, Joong Hoon
2012-12-01
It is essential to select the optimal pressure gauge location for effective management and maintenance of water distribution systems. This study proposes an objective and quantified standard for selecting the optimal pressure gauge location by defining the pressure change at other nodes as a result of demand change at a specific node using entropy theory. Two cases are considered in terms of demand change: that in which demand at all nodes shows peak load by using a peak factor and that comprising the demand change of the normal distribution whose average is the base demand. The actual pressure change pattern is determined by using the emitter function of EPANET to reflect the pressure that changes practically at each node. The optimal pressure gauge location is determined by prioritizing the node that processes the largest amount of information it gives to (giving entropy) and receives from (receiving entropy) the whole system according to the entropy standard. The suggested model is applied to one virtual and one real pipe network, and the optimal pressure gauge location combination is calculated by implementing the sensitivity analysis based on the study results. These analysis results support the following two conclusions. Firstly, the installation priority of the pressure gauge in water distribution networks can be determined with a more objective standard through the entropy theory. Secondly, the model can be used as an efficient decision-making guide for gauge installation in water distribution systems.
Park, Yoon Soo; Lee, Young-Sun; Xing, Kuan
2016-01-01
This study investigates the impact of item parameter drift (IPD) on parameter and ability estimation when the underlying measurement model fits a mixture distribution, thereby violating the item invariance property of unidimensional item response theory (IRT) models. An empirical study was conducted to demonstrate the occurrence of both IPD and an underlying mixture distribution using real-world data. Twenty-one trended anchor items from the 1999, 2003, and 2007 administrations of Trends in International Mathematics and Science Study (TIMSS) were analyzed using unidimensional and mixture IRT models. TIMSS treats trended anchor items as invariant over testing administrations and uses pre-calibrated item parameters based on unidimensional IRT. However, empirical results showed evidence of two latent subgroups with IPD. Results also showed changes in the distribution of examinee ability between latent classes over the three administrations. A simulation study was conducted to examine the impact of IPD on the estimation of ability and item parameters, when data have underlying mixture distributions. Simulations used data generated from a mixture IRT model and estimated using unidimensional IRT. Results showed that data reflecting IPD using mixture IRT model led to IPD in the unidimensional IRT model. Changes in the distribution of examinee ability also affected item parameters. Moreover, drift with respect to item discrimination and distribution of examinee ability affected estimates of examinee ability. These findings demonstrate the need to caution and evaluate IPD using a mixture IRT framework to understand its effects on item parameters and examinee ability. PMID:26941699
NASA Technical Reports Server (NTRS)
Rodriguez, G. (Editor)
1983-01-01
Two general themes in the control of large space structures are addressed: control theory for distributed parameter systems and distributed control for systems requiring spatially-distributed multipoint sensing and actuation. Topics include modeling and control, stabilization, and estimation and identification.
Theory and calculation of water distribution in bentonite in a thermal field
Carnahan, C.L.
1988-09-01
Highly compacted bentonite is under consideration for use as a buffer material in geological repositories for high-level radioactive wastes. To assess the suitability of bentonite for this use, it is necessary to be able to predict the rate and spatial extent of water uptake and water distribution in highly compacted bentonite in the presence of thermal gradients. The ''Buffer Mass Test'' (BMT) was conducted by workers in Sweden as part of the Stripa Project. The BMT measured uptake and spatial distributions of water infiltrating annuli of compacted MX-80 sodium bentonite heated from within and surrounded by granite rock; the measurements provided a body of data very valuable for comparison to results of theoretical calculations. Results of experiments on adsorption of water by highly compacted MX-80 bentonite have been reported by workers in Switzerland. The experiments included measurements of heats of immersion and adsorption-desorption isotherms. These measurements provide the basis for prediction of water vapor pressures in equilibrium with bentonite having specified adsorbed water contents at various temperatures. The present work offers a phenomenological description of the processes influencing movement of water in compacted bentonite in the presence of a variable thermal field. The theory is applied to the bentonite buffer-water system in an assumed steady state of heat and mass transport, using critical data derived from the experimental work done in Switzerland. Results of the theory are compared to distributions of absorbed water in buffers observed in the Swedish BMT experiments. 9 refs., 2 figs.
Adiabatic theory for the population distribution in the evolutionary minority game
NASA Astrophysics Data System (ADS)
Chen, Kan; Wang, Bing-Hong; Yuan, Baosheng
2004-02-01
We study the evolutionary minority game (EMG) using a statistical mechanics approach. We derive a theory for the steady-state population distribution of the agents. The theory is based on an “adiabatic approximation” in which short time fluctuations in the population distribution are integrated out to obtain an effective equation governing the steady-state distribution. We discover the mechanism for the transition from segregation (into opposing groups) to clustering (towards cautious behaviors). The transition is determined by two generic factors: the market impact (of the agents’ own actions) and the short time market inefficiency (arbitrage opportunities) due to fluctuations in the numbers of agents using opposite strategies. A large market impact favors “extreme” players who choose fixed opposite strategies, while large market inefficiency favors cautious players. The transition depends on the number of agents (N) and the effective rate of strategy switching. When N is small, the market impact is relatively large; this favors the extreme behaviors. Frequent strategy switching, on the other hand, leads to a clustering of the cautious agents.
Finite de Finetti theorem for conditional probability distributions describing physical theories
NASA Astrophysics Data System (ADS)
Christandl, Matthias; Toner, Ben
2009-04-01
We work in a general framework where the state of a physical system is defined by its behavior under measurement and the global state is constrained by no-signaling conditions. We show that the marginals of symmetric states in such theories can be approximated by convex combinations of independent and identical conditional probability distributions, generalizing the classical finite de Finetti theorem of Diaconis and Freedman. Our results apply to correlations obtained from quantum states even when there is no bound on the local dimension, so that known quantum de Finetti theorems cannot be used.
Study of isospin nonconservation in the framework of spectral distribution theory
NASA Astrophysics Data System (ADS)
Kar, Kamales; Sarkar, Sukhendusekhar
2015-05-01
The observed isospin-symmetry breaking in light nuclei are caused not only by the Coulomb interaction but also by the isovector one- and two-body plus isotensor two- body nuclear interactions. Spectral distribution theory, which treats nuclear spectroscopy and other structural properties in a statistical framework, has been applied mostly to isospin conserving Hamiltonians. In this paper we extend that to include the nuclear interactions non-scalar in isospin and work out examples in the sd shell to calculate the linear term in the isobaric mass-multiplet equation originating from these non-isoscalar parts.
Analysis of fission-fragment mass distribution within the quantum-mechanical fragmentation theory
NASA Astrophysics Data System (ADS)
Singh, Pardeep; Kaur, Harjeet
2016-11-01
The fission-fragment mass distribution is analysed for the 208Pb(18O, f) reaction within the quantum-mechanical fragmentation theory (QMFT). The reaction potential has been calculated by taking the binding energies, Coulomb potential and proximity potential of all possible decay channels and a stationary Schrödinger equation has been solved numerically to calculate the fission-fragment yield. The overall results for mass distribution are compared with those obtained in experiment. Fine structure dips in yield, corresponding to fragment shell closures at Z = 50 and N=82, which are observed by Bogachev et al., are reproduced successfully in the present calculations. These calculations will help to estimate the formation probabilities of fission fragments and to understand many related phenomena occurring in the fission process.
Khorashadizadeh, S. M. Rastbood, E.; Niknam, A. R.
2015-07-15
The evolution of filamentation instability in a weakly ionized current-carrying plasma with nonextensive distribution was studied in the diffusion frequency region, taking into account the effects of electron-neutral collisions. Using the kinetic theory, Lorentz transformation formulas, and Bhatnagar-Gross-Krook collision model, the generalized dielectric permittivity functions of this plasma system were achieved. By obtaining the dispersion relation of low-frequency waves, the possibility of filamentation instability and its growth rate were investigated. It was shown that collisions can increase the maximum growth rate of instability. The analysis of temporal evolution of filamentation instability revealed that the growth rate of instability increased by increasing the q-parameter and electron drift velocity. Finally, the results of Maxwellian and q-nonextensive velocity distributions were compared and discussed.
Stochastic Growth Theory of Spatially-Averaged Distributions of Langmuir Fields in Earth's Foreshock
NASA Technical Reports Server (NTRS)
Boshuizen, Christopher R.; Cairns, Iver H.; Robinson, P. A.
2001-01-01
Langmuir-like waves in the foreshock of Earth are characteristically bursty and irregular, and are the subject of a number of recent studies. Averaged over the foreshock, it is observed that the probability distribution is power-law P(bar)(log E) in the wave field E with the bar denoting this averaging over position, In this paper it is shown that stochastic growth theory (SGT) can explain a power-law spatially-averaged distributions P(bar)(log E), when the observed power-law variations of the mean and standard deviation of log E with position are combined with the log normal statistics predicted by SGT at each location.
Applications of percolation theory to porous media with distributed local conductances
NASA Astrophysics Data System (ADS)
Hunt, A. G.
Critical path analysis and percolation theory are known to predict accurately dc and low frequency ac electrical conductivity in strongly heterogeneous solids, and have some applications in statistics. Much of this work is dedicated to review the current state of these theories. Application to heterogeneous porous media has been slower, though the concept of percolation was invented in that context. The definition of the critical path is that path which traverses an infinitely large system, with no breaks, which has the lowest possible value of the largest resistance on the path. This resistance is called the rate-limiting, or critical, element, Rc. Mathematical schemes are known for calculating Rc in many cases, but this application is not the focus here. The condition under which critical path analysis and percolation theory are superior to other theories is when heterogeneities are so strong, that transport is largely controlled by a few rate-limiting transitions, and the entire potential field governing the transport is influenced by these individual processes. This is the limit of heterogeneous, deterministic transport, characterized by reproducibility (repeatability). This work goes on to show the issues in which progress with this theoretical approach has been slow (in particular, the relationship between a critical rate, or conductance, and the characteristic conductivity), and what progress is being made towards solving them. It describes applications to saturated and unsaturated flows, some of which are new. The state of knowledge regarding application of cluster statistics of percolation theory to find spatial variability and correlations in the hydraulic conductivity is summarized. Relationships between electrical and hydraulic conductivities are explored. Here, as for the relationship between saturated and unsaturated flows, the approach described includes new applications of existing concepts. The specific case of power-law distributions of pore sizes
Amano, Ken-Ichi; Liang, Yunfeng; Miyazawa, Keisuke; Kobayashi, Kazuya; Hashimoto, Kota; Fukami, Kazuhiro; Nishi, Naoya; Sakka, Tetsuo; Onishi, Hiroshi; Fukuma, Takeshi
2016-08-07
Correction for 'Number density distribution of solvent molecules on a substrate: a transform theory for atomic force microscopy' by Ken-ichi Amano et al., Phys. Chem. Chem. Phys., 2016, 18, 15534-15544.
NASA Astrophysics Data System (ADS)
Scheu, B.; Fowler, A. C.
2015-12-01
Fragmentation is a ubiquitous phenomenon in many natural and engineering systems. It is the process by which an initially competent medium, solid or liquid, is broken up into a population of constituents. Examples occur in collisions and impacts of asteroids/meteorites, explosion driven fragmentation of munitions on a battlefield, as well as of magma in a volcanic conduit causing explosive volcanic eruptions and break-up of liquid drops. Besides the mechanism of fragmentation the resulting frequency-size distribution of the generated constituents is of central interest. Initially their distributions were fitted empirically using lognormal, Rosin-Rammler and Weibull distributions (e.g. Brown & Wohletz 1995). The sequential fragmentation theory (Brown 1989, Wohletz at al. 1989, Wohletz & Brown 1995) and the application of fractal theory to fragmentation products (Turcotte 1986, Perfect 1997, Perugini & Kueppers 2012) attempt to overcome this shortcoming by providing a more physical basis for the applied distribution. Both rely on an at least partially scale-invariant and thus self-similar random fragmentation process. Here we provide a stochastic model for the evolution of grain size distribution during the explosion process. Our model is based on laboratory experiments in which volcanic rock samples explode naturally when rapidly depressurized from initial pressures of several MPa to ambient conditions. The physics governing this fragmentation process has been successfully modelled and the observed fragmentation pattern could be numerically reproduced (Fowler et al. 2010). The fragmentation of these natural rocks leads to grain size distributions which vary depending on the experimental starting conditions. Our model provides a theoretical description of these different grain size distributions. Our model combines a sequential model of the type outlined by Turcotte (1986), but generalized to cater for the explosive process appropriate here, in particular by
Matthews, Thomas J; Whittaker, Robert J
2014-01-01
Published in 2001, The Unified Neutral Theory of Biodiversity and Biogeography (UNTB) emphasizes the importance of stochastic processes in ecological community structure, and has challenged the traditional niche-based view of ecology. While neutral models have since been applied to a broad range of ecological and macroecological phenomena, the majority of research relating to neutral theory has focused exclusively on the species abundance distribution (SAD). Here, we synthesize the large body of work on neutral theory in the context of the species abundance distribution, with a particular focus on integrating ideas from neutral theory with traditional niche theory. First, we summarize the basic tenets of neutral theory; both in general and in the context of SADs. Second, we explore the issues associated with neutral theory and the SAD, such as complications with fitting and model comparison, the underlying assumptions of neutral models, and the difficultly of linking pattern to process. Third, we highlight the advances in understanding of SADs that have resulted from neutral theory and models. Finally, we focus consideration on recent developments aimed at unifying neutral- and niche-based approaches to ecology, with a particular emphasis on what this means for SAD theory, embracing, for instance, ideas of emergent neutrality and stochastic niche theory. We put forward the argument that the prospect of the unification of niche and neutral perspectives represents one of the most promising future avenues of neutral theory research. PMID:25360266
NASA Technical Reports Server (NTRS)
Armand, J. P.
1972-01-01
An extension of classical methods of optimal control theory for systems described by ordinary differential equations to distributed-parameter systems described by partial differential equations is presented. An application is given involving the minimum-mass design of a simply-supported shear plate with a fixed fundamental frequency of vibration. An optimal plate thickness distribution in analytical form is found. The case of a minimum-mass design of an elastic sandwich plate whose fundamental frequency of free vibration is fixed. Under the most general conditions, the optimization problem reduces to the solution of two simultaneous partial differential equations involving the optimal thickness distribution and the modal displacement. One equation is the uniform energy distribution expression which was found by Ashley and McIntosh for the optimal design of one-dimensional structures with frequency constraints, and by Prager and Taylor for various design criteria in one and two dimensions. The second equation requires dynamic equilibrium at the preassigned vibration frequency.
Aono, Shinji; Mori, Toshifumi; Sakaki, Shigeyoshi
2016-03-08
Solvation of transition metal complexes with water has been one of the fundamental topics in physical and coordination chemistry. In particular, Pt(II) complexes have recently attracted considerable interest for their relation to anticancer activity in cisplatin and its analogues, yet the interaction of the water molecule and the metal center has been obscured. The challenge from a theoretical perspective remains that both the microscopic solvation effect and the dynamical electron correlation (DEC) effect have to be treated simultaneously in a reasonable manner. In this work we derive the analytical gradient for the three-dimensional reference interaction site model Møller-Plesset second order (3D-RISM-MP2) free energy. On the basis of the three-regions 3D-RISM self-consistent field (SCF) method recently proposed by us, we apply a new layer of the Z-vector method to the CP-RISM equation as well as point-charge approximation to the derivatives with respect to the density matrix elements in the RISM-CPHF equation to remarkably reduce the computational cost. This method is applied to study the interaction of H2O with the d(8) square planar transition metal complexes in aqueous solution, trans-[Pt(II)Cl2(NH3)(glycine)] (1a), [Pt(II)(NH3)4](2+) (1b), [Pt(II)(CN)4](2-) (1c), and their Pd(II) analogues 2a, 2b, and 2c, respectively, to elucidate whether the usual H2O interaction through O atom (O-ahead mode) or unusual one through H atom (H-ahead mode) is stable in these complexes. We find that the interaction energy of the coordinating water and the transition metal complex changes little when switching from gas to aqueous phase, but the solvation free energy differs remarkably between the two interaction modes, thereby affecting the relative stability of the H-ahead and O-ahead modes. Particularly, in contrast to the expectation that the O-ahead mode is preferred due to the presence of positive charges in 1b, the H-ahead mode is also found to be more stable. The O
ERIC Educational Resources Information Center
Yuan, Ke-Hai; Lu, Laura
2008-01-01
This article provides the theory and application of the 2-stage maximum likelihood (ML) procedure for structural equation modeling (SEM) with missing data. The validity of this procedure does not require the assumption of a normally distributed population. When the population is normally distributed and all missing data are missing at random…
ERIC Educational Resources Information Center
Morgan, Michael; Brickell, Gwyn; Harper, Barry
2008-01-01
This paper explores the application of distributed cognition theory to educational contexts by examining a common learning interaction, the "Copy and Paste" function. After a discussion of distributed cognition and the role of mediating artefacts in real world cognitions, the "Copy and Paste" function is redesigned to embed an effective…
NASA Astrophysics Data System (ADS)
Lee, Hyo-Chang; Chung, Chin-Wook
2015-10-01
Hysteresis, which is the history dependence of physical systems, is one of the most important topics in physics. Interestingly, bi-stability of plasma with a huge hysteresis loop has been observed in inductive plasma discharges. Despite long plasma research, how this plasma hysteresis occurs remains an unresolved question in plasma physics. Here, we report theory, experiment, and modeling of the hysteresis. It was found experimentally and theoretically that evolution of the electron energy distribution (EED) makes a strong plasma hysteresis. In Ramsauer and non-Ramsauer gas experiments, it was revealed that the plasma hysteresis is observed only at high pressure Ramsauer gas where the EED deviates considerably from a Maxwellian shape. This hysteresis was presented in the plasma balance model where the EED is considered. Because electrons in plasmas are usually not in a thermal equilibrium, this EED-effect can be regarded as a universal phenomenon in plasma physics.
Lee, Hyo-Chang; Chung, Chin-Wook
2015-10-20
Hysteresis, which is the history dependence of physical systems, is one of the most important topics in physics. Interestingly, bi-stability of plasma with a huge hysteresis loop has been observed in inductive plasma discharges. Despite long plasma research, how this plasma hysteresis occurs remains an unresolved question in plasma physics. Here, we report theory, experiment, and modeling of the hysteresis. It was found experimentally and theoretically that evolution of the electron energy distribution (EED) makes a strong plasma hysteresis. In Ramsauer and non-Ramsauer gas experiments, it was revealed that the plasma hysteresis is observed only at high pressure Ramsauer gas where the EED deviates considerably from a Maxwellian shape. This hysteresis was presented in the plasma balance model where the EED is considered. Because electrons in plasmas are usually not in a thermal equilibrium, this EED-effect can be regarded as a universal phenomenon in plasma physics.
Lee, Hyo-Chang; Chung, Chin-Wook
2015-01-01
Hysteresis, which is the history dependence of physical systems, is one of the most important topics in physics. Interestingly, bi-stability of plasma with a huge hysteresis loop has been observed in inductive plasma discharges. Despite long plasma research, how this plasma hysteresis occurs remains an unresolved question in plasma physics. Here, we report theory, experiment, and modeling of the hysteresis. It was found experimentally and theoretically that evolution of the electron energy distribution (EED) makes a strong plasma hysteresis. In Ramsauer and non-Ramsauer gas experiments, it was revealed that the plasma hysteresis is observed only at high pressure Ramsauer gas where the EED deviates considerably from a Maxwellian shape. This hysteresis was presented in the plasma balance model where the EED is considered. Because electrons in plasmas are usually not in a thermal equilibrium, this EED-effect can be regarded as a universal phenomenon in plasma physics. PMID:26482650
NASA Technical Reports Server (NTRS)
Anderson, D. E., Jr.; Meier, R. R.; Hodges, R. R., Jr.; Tinsley, B. A.
1987-01-01
The H Balmer alpha nightglow is investigated by using Monte Carlo models of asymmetric geocoronal atomic hydrogen distributions as input to a radiative transfer model of solar Lyman-beta radiation in the thermosphere and atmosphere. It is shown that it is essential to include multiple scattering of Lyman-beta radiation in the interpretation of Balmer alpha airglow data. Observations of diurnal variation in the Balmer alpha airglow showing slightly greater intensities in the morning relative to evening are consistent with theory. No evidence is found for anything other than a single sinusoidal diurnal variation of exobase density. Dramatic changes in effective temperature derived from the observed Balmer alpha line profiles are expected on the basis of changing illumination conditions in the thermosphere and exosphere as different regions of the sky are scanned.
Liu, Yuan; Ning, Chuangang
2015-10-14
Recently, the development of photoelectron velocity map imaging makes it much easier to obtain the photoelectron angular distributions (PADs) experimentally. However, explanations of PADs are only qualitative in most cases, and very limited works have been reported on how to calculate PAD of anions. In the present work, we report a method using the density-functional-theory Kohn-Sham orbitals to calculate the photodetachment cross sections and the anisotropy parameter β. The spherical average over all random molecular orientation is calculated analytically. A program which can handle both the Gaussian type orbital and the Slater type orbital has been coded. The testing calculations on Li(-), C(-), O(-), F(-), CH(-), OH(-), NH2 (-), O2 (-), and S2 (-) show that our method is an efficient way to calculate the photodetachment cross section and anisotropy parameter β for anions, thus promising for large systems.
ρ -meson longitudinal leading-twist distribution amplitude within QCD background field theory
NASA Astrophysics Data System (ADS)
Fu, Hai-Bing; Wu, Xing-Gang; Cheng, Wei; Zhong, Tao
2016-10-01
We revisit the ρ -meson longitudinal leading-twist distribution amplitude (DA) ϕ2;ρ ∥ by using the QCD sum rules approach within the background field theory. To improve the accuracy of the sum rules for its moments ⟨ξn;ρ ∥⟩ , we include the next-to-leading order QCD correction to the perturbative part and keep all nonperturbative condensates up to dimension-six consistently within the background field theory. The first two moments read ⟨ξ2;ρ ∥⟩|1 GeV=0.241 (28 ) and ⟨ξ4;ρ ∥⟩|1 GeV=0.109 (10 ) , indicating a double humped behavior for ϕ2;ρ ∥ at small energy scale. As an application, we apply them to the B →ρ transition form factors within the QCD light-cone sum rules, which are key components for the decay width Γ (B →ρ ℓνℓ) . To compare with the world average of Γ (B →ρ ℓνℓ) issued by Particle Data Group, we predict |Vub|=3.1 9-0.62+0.65 , which agrees with the BABAR and Omnès parametrization prediction within errors.
Vlah, Zvonimir; Seljak, Uroš; Okumura, Teppei; Desjacques, Vincent E-mail: seljak@physik.uzh.ch E-mail: Vincent.Desjacques@unige.ch
2013-10-01
Numerical simulations show that redshift space distortions (RSD) introduce strong scale dependence in the power spectra of halos, with ten percent deviations relative to linear theory predictions even on relatively large scales (k < 0.1h/Mpc) and even in the absence of satellites (which induce Fingers-of-God, FoG, effects). If unmodeled these effects prevent one from extracting cosmological information from RSD surveys. In this paper we use Eulerian perturbation theory (PT) and Eulerian halo biasing model and apply it to the distribution function approach to RSD, in which RSD is decomposed into several correlators of density weighted velocity moments. We model each of these correlators using PT and compare the results to simulations over a wide range of halo masses and redshifts. We find that with an introduction of a physically motivated halo biasing, and using dark matter power spectra from simulations, we can reproduce the simulation results at a percent level on scales up to k ∼ 0.15h/Mpc at z = 0, without the need to have free FoG parameters in the model.
NASA Technical Reports Server (NTRS)
Scudder, J. D.
1978-01-01
A detailed first principle kinetic theory for electrons which is neither a classical fluid treatment nor an exospheric calculation is presented. This theory illustrates the global and local properties of the solar wind expansion that shape the observed features of the electron distribution function, such as its bifurcation, its skewness and the differential temperatures of the thermal and suprathermal subpopulations. Coulomb collisions are substantial mediators of the interplanetary electron velocity distribution function and they place a zone for a bifurcation of the electron distribution function deep in the corona. The local cause and effect precept which permeates the physics of denser media is modified for electrons in the solar wind. The local form of transport laws and equations of state which apply to collision dominated plasmas are replaced with global relations that explicitly depend on the relative position of the observer to the boundaries of the system.
A new measure based on degree distribution that links information theory and network graph analysis
2012-01-01
Background Detailed connection maps of human and nonhuman brains are being generated with new technologies, and graph metrics have been instrumental in understanding the general organizational features of these structures. Neural networks appear to have small world properties: they have clustered regions, while maintaining integrative features such as short average pathlengths. Results We captured the structural characteristics of clustered networks with short average pathlengths through our own variable, System Difference (SD), which is computationally simple and calculable for larger graph systems. SD is a Jaccardian measure generated by averaging all of the differences in the connection patterns between any two nodes of a system. We calculated SD over large random samples of matrices and found that high SD matrices have a low average pathlength and a larger number of clustered structures. SD is a measure of degree distribution with high SD matrices maximizing entropic properties. Phi (Φ), an information theory metric that assesses a system’s capacity to integrate information, correlated well with SD - with SD explaining over 90% of the variance in systems above 11 nodes (tested for 4 to 13 nodes). However, newer versions of Φ do not correlate well with the SD metric. Conclusions The new network measure, SD, provides a link between high entropic structures and degree distributions as related to small world properties. PMID:22726594
A disaggregation theory for predicting concentration gradient distributions in heterogeneous flows
NASA Astrophysics Data System (ADS)
Le Borgne, Tanguy; Huck, Peter; Dentz, Marco; Villermaux, Emmanuel
2016-04-01
Many transport processes occurring in fluid flows depend on concentration gradients, including a wide range of chemical reactions, such as mixing-driven precipitation, and biological processes, such as chemotaxis. A general framework for predicting the distribution of concentration gradients in heterogeneous flow fields is proposed based on a disaggregation theory. The evolution of concentration fields under the combined action of heterogeneous advection and diffusion is quantified from the analysis of the development and aggregation of elementary lamellar structures, which naturally form under the stretching action of flow fields. Therefore spatial correlations in concentrations can be estimated based on the understanding of the lamellae aggregation process that determine the concentration levels at neighboring spatial locations. Using this principle we quantify the temporal evolution of the concentration gradient Probability Density Functions in heterogeneous Darcy fields for arbitrary Peclet numbers. This approach is shown to provide accurate predictions of concentration gradient distributions for a range of flow systems, including turbulent flows and low Reynolds number porous media flows, for confined and dispersing mixtures.
FROM BALLOT THEOREMS TO THE THEORY OF QUEUES,
QUEUEING THEORY, DISTRIBUTION THEORY ), (*PROBABILITY, DISTRIBUTION THEORY ), (* DISTRIBUTION THEORY , QUEUEING THEORY), (*STOCHASTIC PROCESSES... DISTRIBUTION THEORY ), SEQUENCES(MATHEMATICS), DIFFERENCE EQUATIONS, INTEGRAL TRANSFORMS, TIME, STATISTICAL FUNCTIONS
Roles of water in protein structure and function studied by molecular liquid theory.
Imai, Takashi
2009-01-01
The roles of water in the structure and function of proteins have not been completely elucidated. Although molecular simulation has been widely used for the investigation of protein structure and function, it is not always useful for elucidating the roles of water because the effect of water ranges from atomic to thermodynamic level. The three-dimensional reference interaction site model (3D-RISM) theory, which is a statistical-mechanical theory of molecular liquids, can yield the solvation structure at the atomic level and calculate the thermodynamic quantities from the intermolecular potentials. In the last few years, the author and coworkers have succeeded in applying the 3D-RISM theory to protein aqueous solution systems and demonstrated that the theory is useful for investigating the roles of water. This article reviews some of the recent applications and findings, which are concerned with molecular recognition by protein, protein folding, and the partial molar volume of protein which is related to the pressure effect on protein.
NASA Astrophysics Data System (ADS)
Kovalenko, Andriy; Truong, Thanh N.
2000-11-01
We developed a self-consistent three-dimensional reference interaction site model integral equation theory with the molecular hypernetted chain closure (SC-3D-RISM/HNC) for studying thermochemistry of solvation of ionic solutes in a polar molecular solvent. It is free from the inconsistency in the positions of the ion-solvent site distribution peaks, peculiar to the conventional RISM/HNC approach and improves the predictions for the solvation thermodynamics. The SC-3D-RISM treatment can be readily generalized to the case of finite ionic concentrations, including the consistent dielectric corrections to provide a consistent description of the dielectric properties of ion-molecular solution. The proposed theory is tested for hydration of the Na+ and Cl- ions in ambient water at infinite dilution. An improved agreement of the ion hydration structure and thermodynamics with molecular simulation results is found as compared to the conventional RISM/HNC treatment.
Fluctuations/Correlations in Symmetric Diblock Copolymers: Simulations and Theories
NASA Astrophysics Data System (ADS)
Zong, Jing; Yang, Delian; Wang
2012-02-01
Modeling symmetric diblock copolymers as discrete Gaussian chains with soft, finite-range repulsions as commonly used in dissipative-particle dynamics simulations, we have performed fast off-lattice Monte Carlo (FOMC) simulations1 in a canonical ensemble with variable box lengths to study the thermodynamic and structural properties of both the disordered and lamellar phases. Our FOMC results for the disordered phase are further compared, without any parameter-fitting, to those from the reference interaction site model (RISM) and the polymer reference interaction site model (PRISM) theories, as well as the Gaussian fluctuation theory, based on the same model system. Such direct comparisons unambiguously and quantitatively reveal the consequences of various theoretical approximations and the validity of these theories in describing the fluctuations/correlations in disordered diblock copolymers. [4pt] [1] Q. Wang and Y. Yin, J. Chem. Phys., 130, 104903 (2009).
NASA Astrophysics Data System (ADS)
Wendt, Kyle
2016-03-01
How large is the 48Ca nucleus? While the electric charge distribution of this nucleus was accurately measured decades ago, both experimental and ab initio descriptions of the neutron distribution are deficient. We address this question using ab initio calculations of the electric charge, neutron, and weak distributions of 48Ca based on chiral effective field theory. Historically, chiral effective field theory calculations of systems larger than 4 nucleons have been plagued by strong systematic errors which result in theoretical descriptions that are too dense and over bound. We address these errors using a novel approach that permits us to accurately reproduce binding energy and charge radius of 48Ca, and to constrain electroweak observables such as the neutron radius, electric dipole polarizability, and the weak form factor. For a full list of contributors to this work, please see ``Neutron and weak-charge distributions of the 48Ca nucleus,'' Nature Physics (2015) doi:10.1038/nphys3529.
Dekkers, Petrus J; Tuinman, Ilse L; Marijnissen, Jan C M; Friedlander, Sheldon K; Scarlett, B
2002-04-15
The gas to particle synthesis route is a relatively clean and efficient manner for the production of high-quality ceramic powders. These powders can be subsequently sintered in any wanted shape. The modeling of these production systems is difficult because several mechanisms occur in parallel. From theoretical considerations it can be determined, however, that coagulation and sintering are dominant mechanisms as far as shape and size of the particles are considered. In part I of this article an extensive theoretical analysis was given on the self-preserving size distribution theory for power law particles. In this second part, cumulative particle size distributions of silicon and silicon nitride agglomerates, produced in a laser reactor, were determined from TEM pictures and compared to the distributions calculated from this self-preserving theory for power law particles. The calculated distributions were in fair agreement with the measured results, especially at the high end of the distributions. Calculated and measured particle growth rates were also in fair agreement. Using the self-preserving theory an analysis was made on the distribution of annealed silicon agglomerates, of interest in applications to nanoparticle technology.
Liu, Yuan; Ning, Chuangang
2015-10-14
Recently, the development of photoelectron velocity map imaging makes it much easier to obtain the photoelectron angular distributions (PADs) experimentally. However, explanations of PADs are only qualitative in most cases, and very limited works have been reported on how to calculate PAD of anions. In the present work, we report a method using the density-functional-theory Kohn-Sham orbitals to calculate the photodetachment cross sections and the anisotropy parameter β. The spherical average over all random molecular orientation is calculated analytically. A program which can handle both the Gaussian type orbital and the Slater type orbital has been coded. The testing calculations on Li{sup −}, C{sup −}, O{sup −}, F{sup −}, CH{sup −}, OH{sup −}, NH{sub 2}{sup −}, O{sub 2}{sup −}, and S{sub 2}{sup −} show that our method is an efficient way to calculate the photodetachment cross section and anisotropy parameter β for anions, thus promising for large systems.
Force-field functor theory: classical force-fields which reproduce equilibrium quantum distributions
Babbush, Ryan; Parkhill, John; Aspuru-Guzik, Alán
2013-01-01
Feynman and Hibbs were the first to variationally determine an effective potential whose associated classical canonical ensemble approximates the exact quantum partition function. We examine the existence of a map between the local potential and an effective classical potential which matches the exact quantum equilibrium density and partition function. The usefulness of such a mapping rests in its ability to readily improve Born-Oppenheimer potentials for use with classical sampling. We show that such a map is unique and must exist. To explore the feasibility of using this result to improve classical molecular mechanics, we numerically produce a map from a library of randomly generated one-dimensional potential/effective potential pairs then evaluate its performance on independent test problems. We also apply the map to simulate liquid para-hydrogen, finding that the resulting radial pair distribution functions agree well with path integral Monte Carlo simulations. The surprising accessibility and transferability of the technique suggest a quantitative route to adapting Born-Oppenheimer potentials, with a motivation similar in spirit to the powerful ideas and approximations of density functional theory. PMID:24790954
Babbush, Ryan; Parkhill, John; Aspuru-Guzik, Alán
2013-01-01
Feynman and Hibbs were the first to variationally determine an effective potential whose associated classical canonical ensemble approximates the exact quantum partition function. We examine the existence of a map between the local potential and an effective classical potential which matches the exact quantum equilibrium density and partition function. The usefulness of such a mapping rests in its ability to readily improve Born-Oppenheimer potentials for use with classical sampling. We show that such a map is unique and must exist. To explore the feasibility of using this result to improve classical molecular mechanics, we numerically produce a map from a library of randomly generated one-dimensional potential/effective potential pairs then evaluate its performance on independent test problems. We also apply the map to simulate liquid para-hydrogen, finding that the resulting radial pair distribution functions agree well with path integral Monte Carlo simulations. The surprising accessibility and transferability of the technique suggest a quantitative route to adapting Born-Oppenheimer potentials, with a motivation similar in spirit to the powerful ideas and approximations of density functional theory.
Swartz, M A; Berk, D A; Jain, R K
1996-01-01
We present a novel integrative method for characterizing transport in the lymphatic capillaries in the tail of the anesthetized mouse, which is both sensitive and reproducible for quantifying uptake and flow. Interstitially injected, fluorescently labeled macromolecules were used to visualize and quantify these processes. Residence time distribution (RTD) theory was employed to measure net flow velocity in the lymphatic network as well as to provide a relative measure of lymphatic uptake of macromolecules from the interstitium. The effects of particle size and injection pressure were determined. The uptake rate was found to be independent of particle size in the range of a 6- to 18-nm radius; beyond this size, the interstitial matrix seemed to pose a greater barrier. A comparison of 10 vs. 40 cmH2O injection pressure showed a significant influence on the relative uptake rate but not on the net velocity within the network (3.3 +/- 0.8 vs. 3.8 +/- 1.0 micron/s). This suggested the presence of a systemic driving force for baseline lymph propulsion that is independent of the local pressure gradients driving the uptake. This model can be used to examine various aspects of transport physiology of the initial lymphatics.
The application of age distribution theory in the analysis of cytofluorimetric DNA histogram data.
Watson, J V
1977-03-01
Age distribution theory has been employed in a model to analyse a variety of histograms of the DNA content of single cells in samples from experimental tumours growing in tissue culture. The method has produced satisfactory correspondence with the experimental data in which there was a wide variation in the proportions of cells in the intermitotic phases, and generally good agreement between the 3H-thymidine labelling index and the computed proportion in S phase. The model has the capacity to analyse data from populations which contain a proportion of non-cycling cells. However, it is concluded that reliable results for the growth fraction and also for the relative durations of the intermitotic phase times cannot be obtained for the data reported here from the DNA histograms alone. To obtain reliable estimates of the growth fraction the relative durations of the phase time must be known, and conversely, reliable estimates of the relative phase durations can only be obtained if the growth fraction is known.
NASA Astrophysics Data System (ADS)
Lee, Hyo-Chang; Chung, Chin-Wook
2016-09-01
Hysteresis, which is the history dependence of physical systems, indicates that there are more-than-two stable points in a given condition, and it has been considered to one of the most important topics in fundamental physics. Recently, the hysteresis of plasma has become a focus of research because stable plasma operation is very important for fusion reactors, bio-medical plasmas, and industrial plasmas for nano-device fabrication process. Interestingly, the bi-stability characteristics of plasma with a huge hysteresis loop have been observed in inductive discharge plasmas Because hysteresis study in such plasmas can provide a universal understanding of plasma physics, many researchers have attempted experimental and theoretical studies. Despite long plasma research, how this plasma hysteresis occurs remains an unresolved question in plasma physics. Here, we report theory, experiment, and modeling of the hysteresis. It was found experimentally and theoretically that evolution of the electron energy distribution (EED) makes a strong plasma hysteresis. In Ramsauer and non-Ramsauer gas experiments, it was revealed that the plasma hysteresis is observed only at high pressure Ramsauer gas where the EED deviates considerably from a Maxwellian shape. This hysteresis was presented in the plasma balance model where the EED is considered. Because electrons in plasmas are usually not in a thermal equilibrium, this EED-effect can be regarded as a universal phenomenon in plasma physics. This research was partially supported by Korea Research Institute of Standard and Science.
ERIC Educational Resources Information Center
Algina, James; Keselman, H. J.
2008-01-01
Applications of distribution theory for the squared multiple correlation coefficient and the squared cross-validation coefficient are reviewed, and computer programs for these applications are made available. The applications include confidence intervals, hypothesis testing, and sample size selection. (Contains 2 tables.)
A molecular theory of liquid interfaces.
Kovalenko, Andriy; Hirata, Fumio
2005-04-21
We propose a site site generalization of the Lovett-Mow-Buff-Wertheim integro-differential equation for the one-particle density distributions to polyatomic fluids. The method provides microscopic description of liquid interfaces of molecular fluids and solutions. It uses the inhomogeneous site-site direct correlation function of molecular fluid consistently constructed by nonlinear interpolation between the homogeneous ones. The site site correlations of the coexisting bulk phases are obtained from the reference interaction site model (RISM) integral equation with our closure approximation. For illustration, we calculated the structure of the planar liquid-vapor as well as liquid-liquid interfaces of n-hexane and methanol at ambient conditions.
NASA Technical Reports Server (NTRS)
Scudder, J. D.; Olbert, S.
1979-01-01
A kinetic theory for the velocity distribution of solar wind electrons which illustrates the global and local properties of the solar wind expansion is proposed. By means of the Boltzmann equation with the Krook collision operator accounting for Coulomb collisions, it is found that Coulomb collisions determine the population and shape of the electron distribution function in both the thermal and suprathermal energy regimes. For suprathermal electrons, the cumulative effects of Coulomb interactions are shown to take place on the scale of the heliosphere itself, whereas the Coulomb interactions of thermal electrons occur on a local scale near the point of observation (1 AU). The bifurcation of the electron distribution between thermal and suprathermal electrons is localized to the deep solar corona (1 to 10 solar radii).
Aquilanti, Vincenzo; Coutinho, Nayara Dantas; Carvalho-Silva, Valter Henrique
2017-04-28
This article surveys the empirical information which originated both by laboratory experiments and by computational simulations, and expands previous understanding of the rates of chemical processes in the low-temperature range, where deviations from linearity of Arrhenius plots were revealed. The phenomenological two-parameter Arrhenius equation requires improvement for applications where interpolation or extrapolations are demanded in various areas of modern science. Based on Tolman's theorem, the dependence of the reciprocal of the apparent activation energy as a function of reciprocal absolute temperature permits the introduction of a deviation parameter d covering uniformly a variety of rate processes, from those where quantum mechanical tunnelling is significant and d < 0, to those where d > 0, corresponding to the Pareto-Tsallis statistical weights: these generalize the Boltzmann-Gibbs weight, which is recovered for d = 0. It is shown here how the weights arise, relaxing the thermodynamic equilibrium limit, either for a binomial distribution if d > 0 or for a negative binomial distribution if d < 0, formally corresponding to Fermion-like or Boson-like statistics, respectively. The current status of the phenomenology is illustrated emphasizing case studies; specifically (i) the super-Arrhenius kinetics, where transport phenomena accelerate processes as the temperature increases; (ii) the sub-Arrhenius kinetics, where quantum mechanical tunnelling propitiates low-temperature reactivity; (iii) the anti-Arrhenius kinetics, where processes with no energetic obstacles are rate-limited by molecular reorientation requirements. Particular attention is given for case (i) to the treatment of diffusion and viscosity, for case (ii) to formulation of a transition rate theory for chemical kinetics including quantum mechanical tunnelling, and for case (iii) to the stereodirectional specificity of the dynamics of reactions strongly hindered by the
Heavy pseudoscalar twist-3 distribution amplitudes within QCD theory in background fields
NASA Astrophysics Data System (ADS)
Zhong, Tao; Wu, Xing-Gang; Huang, Tao; Fu, Hai-Bing
2016-09-01
In this paper, we study the properties of the twist-3 distribution amplitude (DA) of the heavy pseudoscalars such as η _c, B_c, and η _b. New sum rules for the twist-3 DA moments < ξ ^n_Prangle _HP and < ξ ^n_σ rangle _HP up to sixth order and up to dimension-six condensates are deduced under the framework of the background field theory. Based on the sum rules for the twist-3 DA moments, we construct a new model for the two twist-3 DAs of the heavy pseudoscalar with the help of the Brodsky-Huang-Lepage prescription. Furthermore, we apply them to the B_c→ η _c transition form factor (f^{B_c→ η _c}_+(q^2)) within the light-cone sum rules approach, and the results are comparable with other approaches. It has been found that the twist-3 DAs φ ^P_{3;η _c} and φ ^σ _{3;η _c} are important for a reliable prediction of f^{B_c→ η _c}_+(q^2). For example, at the maximum recoil region, we have f^{B_c→ η _c}_+(0) = 0.674 ± 0.066, in which those two twist-3 terms provide {˜ }33 and {˜ }22 % contributions. Also we calculate the branching ratio of the semi-leptonic decay B_c → η _c lν as Br(B_c → η _c lν ) = ( 9.31^{+2.27}_{-2.01} ) × 10^{-3}.
Vlah, Zvonimir; Seljak, Uroš; Baldauf, Tobias; McDonald, Patrick; Okumura, Teppei E-mail: seljak@physik.uzh.ch E-mail: teppei@ewha.ac.kr
2012-11-01
We develop a perturbative approach to redshift space distortions (RSD) using the phase space distribution function approach and apply it to the dark matter redshift space power spectrum and its moments. RSD can be written as a sum over density weighted velocity moments correlators, with the lowest order being density, momentum density and stress energy density. We use standard and extended perturbation theory (PT) to determine their auto and cross correlators, comparing them to N-body simulations. We show which of the terms can be modeled well with the standard PT and which need additional terms that include higher order corrections which cannot be modeled in PT. Most of these additional terms are related to the small scale velocity dispersion effects, the so called finger of god (FoG) effects, which affect some, but not all, of the terms in this expansion, and which can be approximately modeled using a simple physically motivated ansatz such as the halo model. We point out that there are several velocity dispersions that enter into the detailed RSD analysis with very different amplitudes, which can be approximately predicted by the halo model. In contrast to previous models our approach systematically includes all of the terms at a given order in PT and provides a physical interpretation for the small scale dispersion values. We investigate RSD power spectrum as a function of μ, the cosine of the angle between the Fourier mode and line of sight, focusing on the lowest order powers of μ and multipole moments which dominate the observable RSD power spectrum. Overall we find considerable success in modeling many, but not all, of the terms in this expansion. This is similar to the situation in real space, but predicting power spectrum in redshift space is more difficult because of the explicit influence of small scale dispersion type effects in RSD, which extend to very large scales.
Marshall, Bennett D; Chapman, Walter G
2013-08-07
We develop a new theory for associating fluids with multiple association sites. The theory accounts for small bond angle effects such as steric hindrance, ring formation, and double bonding. The theory is validated against Monte Carlo simulations for the case of a fluid of patchy colloid particles with three patches and is found to be very accurate. Once validated, the theory is applied to study the phase diagram of a fluid composed of three patch colloids. It is found that bond angle has a significant effect on the phase diagram and the very existence of a liquid-vapor transition.
Luding, Stefan; Santos, Andrés
2004-11-01
We report molecular dynamics results for the contact values of the radial distribution functions of binary additive mixtures of hard disks. The simulation data are compared with theoretical predictions from expressions proposed by Jenkins and Mancini [J. Appl. Mech. 54, 27 (1987)] and Santos et al. [J. Chem. Phys. 117, 5785 (2002)]. Both theories agree quantitatively within a very small margin, which renders the former still a very useful and simple tool to work with. The latter (higher-order and self-consistent) theory provides a small qualitative correction for low densities and is superior especially in the high-density domain.
Direct simulation of groundwater transit-time distributions using the reservoir theory
NASA Astrophysics Data System (ADS)
Etcheverry, David; Perrochet, Pierre
Groundwater transit times are of interest for the management of water resources, assessment of pollution from non-point sources, and quantitative dating of groundwaters by the use of environmental isotopes. The age of water is the time water has spent in an aquifer since it has entered the system, whereas the transit time is the age of water as it exits the system. Water at the outlet of an aquifer is a mixture of water elements with different transit times, as a consequence of the different flow-line lengths. In this paper, transit-time distributions are calculated by coupling two existing methods, the reservoir theory and a recent age-simulation method. Based on the derivation of the cumulative age distribution over the whole domain, the approach accounts for the whole hydrogeological framework. The method is tested using an analytical example and its applicability illustrated for a regional layered aquifer. Results show the asymmetry and multimodality of the transit-time distribution even in advection-only conditions, due to the aquifer geometry and to the velocity-field heterogeneity. Résumé Les temps de transit des eaux souterraines sont intéressants à connaître pour gérer l'évaluation des ressources en eau dans le cas de pollution à partir de sources non ponctuelles, et aussi pour dater quantitativement les eaux souterraines au moyen des isotopes du milieu. L'âge de l'eau est le temps qu'elle a passé dans un aquifère depuis qu'elle est entrée dans le système, alors que le temps de transit est l'âge de l'eau au moment où elle quitte le système. L'eau à la sortie d'un aquifère est un mélange d'eaux possédant différents temps de transit, du fait des longueurs différentes des lignes de courant suivies. Dans ce papier, les distributions des temps de transit sont calculées en couplant deux méthodes, la théorie du réservoir et une méthode récente de simulation des âges. Basée sur la dérivation de la distribution cumulées des âges sur
Qin, Jiahu; Fu, Weiming; Gao, Huijun; Zheng, Wei Xing
2016-03-03
This paper is concerned with developing a distributed k-means algorithm and a distributed fuzzy c-means algorithm for wireless sensor networks (WSNs) where each node is equipped with sensors. The underlying topology of the WSN is supposed to be strongly connected. The consensus algorithm in multiagent consensus theory is utilized to exchange the measurement information of the sensors in WSN. To obtain a faster convergence speed as well as a higher possibility of having the global optimum, a distributed k-means++ algorithm is first proposed to find the initial centroids before executing the distributed k-means algorithm and the distributed fuzzy c-means algorithm. The proposed distributed k-means algorithm is capable of partitioning the data observed by the nodes into measure-dependent groups which have small in-group and large out-group distances, while the proposed distributed fuzzy c-means algorithm is capable of partitioning the data observed by the nodes into different measure-dependent groups with degrees of membership values ranging from 0 to 1. Simulation results show that the proposed distributed algorithms can achieve almost the same results as that given by the centralized clustering algorithms.
Okie, Jordan G; Van Horn, David J; Storch, David; Barrett, John E; Gooseff, Michael N; Kopsova, Lenka; Takacs-Vesbach, Cristina D
2015-06-22
The causes of biodiversity patterns are controversial and elusive due to complex environmental variation, covarying changes in communities, and lack of baseline and null theories to differentiate straightforward causes from more complex mechanisms. To address these limitations, we developed general diversity theory integrating metabolic principles with niche-based community assembly. We evaluated this theory by investigating patterns in the diversity and distribution of soil bacteria taxa across four orders of magnitude variation in spatial scale on an Antarctic mountainside in low complexity, highly oligotrophic soils. Our theory predicts that lower temperatures should reduce taxon niche widths along environmental gradients due to decreasing growth rates, and the changing niche widths should lead to contrasting α- and β-diversity patterns. In accord with the predictions, α-diversity, niche widths and occupancies decreased while β-diversity increased with increasing elevation and decreasing temperature. The theory also successfully predicts a hump-shaped relationship between α-diversity and pH and a negative relationship between α-diversity and salinity. Thus, a few simple principles explained systematic microbial diversity variation along multiple gradients. Such general theory can be used to disentangle baseline effects from more complex effects of temperature and other variables on biodiversity patterns in a variety of ecosystems and organisms.
Okie, Jordan G.; Van Horn, David J.; Storch, David; Barrett, John E.; Gooseff, Michael N.; Kopsova, Lenka; Takacs-Vesbach, Cristina D.
2015-01-01
The causes of biodiversity patterns are controversial and elusive due to complex environmental variation, covarying changes in communities, and lack of baseline and null theories to differentiate straightforward causes from more complex mechanisms. To address these limitations, we developed general diversity theory integrating metabolic principles with niche-based community assembly. We evaluated this theory by investigating patterns in the diversity and distribution of soil bacteria taxa across four orders of magnitude variation in spatial scale on an Antarctic mountainside in low complexity, highly oligotrophic soils. Our theory predicts that lower temperatures should reduce taxon niche widths along environmental gradients due to decreasing growth rates, and the changing niche widths should lead to contrasting α- and β-diversity patterns. In accord with the predictions, α-diversity, niche widths and occupancies decreased while β-diversity increased with increasing elevation and decreasing temperature. The theory also successfully predicts a hump-shaped relationship between α-diversity and pH and a negative relationship between α-diversity and salinity. Thus, a few simple principles explained systematic microbial diversity variation along multiple gradients. Such general theory can be used to disentangle baseline effects from more complex effects of temperature and other variables on biodiversity patterns in a variety of ecosystems and organisms. PMID:26019154
1980-09-29
FOUNDATIONS OF EIGENVALUE DISTRIBUTION THEORY FOR GENERAL A NON--ETC(U) SEP 80 M MARCUS, M GOLDBERG, M NEWMAN AFOSR-79-0127 UNCLASSIFIED AFOSR-TR-80...September 1980 Title of Research: Foundations of Eigenvalue Distribution Theory for General & Nonnegative Matrices, Stability Criteria for Hyperbolic
NASA Astrophysics Data System (ADS)
Pimpinelli, Alberto; Einstein, T. L.; González, Diego Luis; Sathiyanarayanan, Rajesh; Hamouda, Ajmi Bh.
2011-03-01
Earlier we showed [PRL 99, 226102 (2007)] that the CZD in growth could be well described by P (s) = asβ exp (-bs2) , where s is the CZ area divided by its average value. Painstaking simulations by Amar's [PRE 79, 011602 (2009)] and Evans's [PRL 104, 149601 (2010)] groups showed inadequacies in our mean field Fokker-Planck argument relating β to the critical nucleus size. We refine our derivation to retrieve their β ~ i + 2 [PRL 104, 149602 (2010)]. We discuss applications of this formula and methodology to experiments on Ge/Si(001) and on various organics on Si O2 , as well as to kinetic Monte Carlo studies homoepitaxial growth on Cu(100) with codeposited impurities of different sorts. In contrast to theory, there can be significant changes to β with coverage. Some experiments also show temperature dependence. Supported by NSF-MRSEC at UMD, Grant DMR 05-20471.
Akemann, G; Bloch, J; Shifrin, L; Wettig, T
2008-01-25
We analyze how individual eigenvalues of the QCD Dirac operator at nonzero quark chemical potential are distributed in the complex plane. Exact and approximate analytical results for both quenched and unquenched distributions are derived from non-Hermitian random matrix theory. When comparing these to quenched lattice QCD spectra close to the origin, excellent agreement is found for zero and nonzero topology at several values of the quark chemical potential. Our analytical results are also applicable to other physical systems in the same symmetry class.
NASA Astrophysics Data System (ADS)
Tsuchiya, Toshiaki; Lenahan, Patrick M.
2017-03-01
We carried out a unique and systematic characterization of single amphoteric Si/SiO2 interface traps using the charge pumping (CP) method. As a result, we obtained the distribution of the energy levels of these traps for the first time. The distribution is reasonably similar to that of the P b0 density of states reported previously. By considering the essential nature of these traps (i.e., those with two energy levels), factors depending on the energy levels, and the Coulomb interactions between traps, we fundamentally corrected the conventional CP theory.
Zhang, Zhe; Kong, Xiangping; Yin, Xianggen; Yang, Zengli; Wang, Lijun
2014-01-01
In order to solve the problems of the existing wide-area backup protection (WABP) algorithms, the paper proposes a novel WABP algorithm based on the distribution characteristics of fault component current and improved Dempster/Shafer (D-S) evidence theory. When a fault occurs, slave substations transmit to master station the amplitudes of fault component currents of transmission lines which are the closest to fault element. Then master substation identifies suspicious faulty lines according to the distribution characteristics of fault component current. After that, the master substation will identify the actual faulty line with improved D-S evidence theory based on the action states of traditional protections and direction components of these suspicious faulty lines. The simulation examples based on IEEE 10-generator-39-bus system show that the proposed WABP algorithm has an excellent performance. The algorithm has low requirement of sampling synchronization, small wide-area communication flow, and high fault tolerance. PMID:25050399
Studies of the Intrinsic Complexities of Magnetotail Ion Distributions: Theory and Observations
NASA Technical Reports Server (NTRS)
Ashour-Abdalla, Maha
1998-01-01
This year we have studied the relationship between the structure seen in measured distribution functions and the detailed magnetospheric configuration. Results from our recent studies using time-dependent large-scale kinetic (LSK) calculations are used to infer the sources of the ions in the velocity distribution functions measured by a single spacecraft (Geotail). Our results strongly indicate that the different ion sources and acceleration mechanisms producing a measured distribution function can explain this structure. Moreover, individual structures within distribution functions were traced back to single sources. We also confirmed the fractal nature of ion distributions.
NASA Astrophysics Data System (ADS)
Richards, Howard L.; Einstein, T. L.
2000-03-01
The so-called generalized Wigner distribution (GWD) has been shown to provide an excellent description of terrace width distributions (TWDs) on vicinal surfaces for which there are repulsive interactions between steps that are proportional to the inverse square of the step separation.(T. L. Einstein and O. Pierre-Louis, Surface Sci. 424), L299 (1999). (S. D. Cohen, H. L. Richards, and T. L. Einstein, preprint.) Until recently, however, there was no plausible physical explanation for the excellent agreement between the GWD and the TWDs observed in Monte Carlo simulations^3 or derived from a few integrable models.^2 Here we show that the GWD can be derived from a mean-field approximation similar in spirit to the Gruber-Mullins approximation.(E. E. Gruber and W. W. Mullins, J. Phys. Chem. Solids 28), 875 (1967) This mean-field treatment can be generalized to other forms of step-step repulsions; the resulting predictions are in good agreement with Monte Carlo simulations. Finally, the process can be inverted to allow nontrivial step-step interactions to be extracted from experimental TWDs.
2016-06-02
is derived to facilitate use of secondary polarization. The model is supported by exper- imental MFOV lidar measurements carried out in a controlled ...Retrieval of droplet-size density distribution from multiple-field-of- view cross-polarized lidar signals: theory and experimental validation...Gilles Roy, Luc Bissonnette, Christian Bastille, and Gilles Vallee Multiple-field-of- view (MFOV) secondary-polarization lidar signals are used to
NASA Astrophysics Data System (ADS)
Cyr-Racine, Francis-Yan; Sigurdson, Kris; Zavala, Jesús; Bringmann, Torsten; Vogelsberger, Mark; Pfrommer, Christoph
2016-06-01
We formulate an effective theory of structure formation (ETHOS) that enables cosmological structure formation to be computed in almost any microphysical model of dark matter physics. This framework maps the detailed microphysical theories of particle dark matter interactions into the physical effective parameters that shape the linear matter power spectrum and the self-interaction transfer cross section of nonrelativistic dark matter. These are the input to structure formation simulations, which follow the evolution of the cosmological and galactic dark matter distributions. Models with similar effective parameters in ETHOS but with different dark particle physics would nevertheless result in similar dark matter distributions. We present a general method to map an ultraviolet complete or effective field theory of low-energy dark matter physics into parameters that affect the linear matter power spectrum and carry out this mapping for several representative particle models. We further propose a simple but useful choice for characterizing the dark matter self-interaction transfer cross section that parametrizes self-scattering in structure formation simulations. Taken together, these effective parameters in ETHOS allow the classification of dark matter theories according to their structure formation properties rather than their intrinsic particle properties, paving the way for future simulations to span the space of viable dark matter physics relevant for structure formation.
General Deformation (Elastic and Inelastic) and Stress Distribution Theory in Soils.
1977-09-01
pavement structure can be completely simulated in laboratory tests based on the theory. Continuation of this research is being sponsored by the Department of Transportation, Transportation Systems Center . (Author)
Aitken, R J; Elton, R A
1984-11-01
The value of Poisson distribution theory in describing and predicting the nature of sperm-egg interaction in vitro has been investigated using an interspecific in-vitro fertilization system, incorporating zona-free hamster oocytes and human spermatozoa. The frequency distribution of polyspermic oocyte penetrations in 72 experiments exhibited good agreement with the Poisson distribution at all levels of fertilization indicating that each oocyte must be of equal penetrability and that there can be no block to polyspermy in this interspecific system. Poisson distribution theory also accurately described the relationship between oocyte penetration and sperm motility in 50 out of 54 separate experiments spread across 10 serial dilution curves. For each dilution series the shape of the fitted curve was fixed but its location along the x-axis varied from donor to donor. The fixed nature of the relationship between sperm motility and egg penetration enables the results of such in-vitro fertilization experiments to be corrected for the number of motile spermatozoa in the incubation media. On the basis of these findings a protocol is described for assessing the results of the zona-free hamster oocyte penetration assay, which involves analysis of the degree of polyspermy followed by the application of Poisson distribution theory to correct the results to a standard concentration of motile spermatozoa. Changes in the penetrating ability of human spermatozoa after vasectomy and characterization of the degree of inter-ejaculate variation in penetrating potential are two clinical examples of such analyses given in the text. The statistical methods described in this paper should also be of general relevance to the study of fertilization mechanisms, in providing a rationale by which to analyse the quantitative nature of sperm-egg interaction in vitro.
NASA Astrophysics Data System (ADS)
Bhandari, A.; Hamre, B.; Frette, Ø.; Stamnes, K.; Stamnes, J. J.
2011-07-01
We used size distributions of volume equivalent spherical particles with complex refractive index to model the inherent optical properties (IOPs) in four different layers of human skin at ten different wavelengths in the visible and near-infrared spectral bands. For each layer, we first computed the size-averaged absorption coefficient, scattering coefficient, and asymmetry factor for the collection of particles in a host medium using Mie theory and compared these IOPs in each layer with those obtained from a bio-optical model (BOM). This procedure was repeated, using an optimization scheme, until satisfactory agreement was obtained between the IOPs obtained from the particle size distribution and those given by the BOM. The size distribution as well as the complex refractive index of the particles, obtained from this modeling exercise, can be used to compute the phase matrix, which is an essential input to model polarized light transport in human skin tissue.
ERIC Educational Resources Information Center
Larwin, Karen H.; Larwin, David A.
2011-01-01
Bootstrapping methods and random distribution methods are increasingly recommended as better approaches for teaching students about statistical inference in introductory-level statistics courses. The authors examined the effect of teaching undergraduate business statistics students using random distribution and bootstrapping simulations. It is the…
Unravelling the size distribution of social groups with information theory in complex networks
NASA Astrophysics Data System (ADS)
Hernando, A.; Villuendas, D.; Vesperinas, C.; Abad, M.; Plastino, A.
2010-07-01
The minimization of Fisher’s information (MFI) approach of Frieden et al. [Phys. Rev. E 60, 48 (1999)] is applied to the study of size distributions in social groups on the basis of a recently established analogy between scale invariant systems and classical gases [Phys. A 389, 490 (2010)]. Going beyond the ideal gas scenario is seen to be tantamount to simulating the interactions taking place, for a competitive cluster growth process, in a scale-free ideal network - a non-correlated network with a connection-degree’s distribution that mimics the scale-free ideal gas density distribution. We use a scaling rule that allows one to classify the final cluster-size distributions using only one parameter that we call the competitiveness, which can be seen as a measure of the strength of the interactions. We find that both empirical city-size distributions and electoral results can be thus reproduced and classified according to this competitiveness-parameter, that also allow us to infer the maximum number of stable social relationships that one person can maintain, known as the Dunbar number, together with its standard deviation. We discuss the importance of this number in connection with the empirical phenomenon known as “six-degrees of separation”. Finally, we show that scaled city-size distributions of large countries follow, in general, the same universal distribution.
Maximum entropy principle based estimation of performance distribution in queueing theory.
He, Dayi; Li, Ran; Huang, Qi; Lei, Ping
2014-01-01
In related research on queuing systems, in order to determine the system state, there is a widespread practice to assume that the system is stable and that distributions of the customer arrival ratio and service ratio are known information. In this study, the queuing system is looked at as a black box without any assumptions on the distribution of the arrival and service ratios and only keeping the assumption on the stability of the queuing system. By applying the principle of maximum entropy, the performance distribution of queuing systems is derived from some easily accessible indexes, such as the capacity of the system, the mean number of customers in the system, and the mean utilization of the servers. Some special cases are modeled and their performance distributions are derived. Using the chi-square goodness of fit test, the accuracy and generality for practical purposes of the principle of maximum entropy approach is demonstrated.
Studies of the Intrinsic Complexities of Magnetotail Ion Distributions: Theory and Observations
NASA Technical Reports Server (NTRS)
Ashour-Abdalla, M.
1999-01-01
We have studied the relationship between the structure seen in measured distribution functions and the detailed magnetospheric configuration. Results from our recent studies using time-dependent large-scale kinetic (LSK) calculations are used to infer the sources of the ions in the velocity distribution functions measured by a single spacecraft (Geotail). Our results strongly indicate that the different ion sources and acceleration mechanisms producing a measured distribution function can explain this structure. Moreover, individual structures within distribution functions were traced back to single sources. We also examined the intrinsic variability of the magnetotail during quiet and steady solar wind conditions and found that the magnetotail possess an intrinsic variability caused by the non-adiabatic acceleration and loss of current-carrying ions from the magnetotail current sheet.
Advances in numerical solutions to integral equations in liquid state theory
NASA Astrophysics Data System (ADS)
Howard, Jesse J.
Solvent effects play a vital role in the accurate description of the free energy profile for solution phase chemical and structural processes. The inclusion of solvent effects in any meaningful theoretical model however, has proven to be a formidable task. Generally, methods involving Poisson-Boltzmann (PB) theory and molecular dynamic (MD) simulations are used, but they either fail to accurately describe the solvent effects or require an exhaustive computation effort to overcome sampling problems. An alternative to these methods are the integral equations (IEs) of liquid state theory which have become more widely applicable due to recent advancements in the theory of interaction site fluids and the numerical methods to solve the equations. In this work a new numerical method is developed based on a Newton-type scheme coupled with Picard/MDIIS routines. To extend the range of these numerical methods to large-scale data systems, the size of the Jacobian is reduced using basis functions, and the Newton steps are calculated using a GMRes solver. The method is then applied to calculate solutions to the 3D reference interaction site model (RISM) IEs of statistical mechanics, which are derived from first principles, for a solute model of a pair of parallel graphene plates at various separations in pure water. The 3D IEs are then extended to electrostatic models using an exact treatment of the long-range Coulomb interactions for negatively charged walls and DNA duplexes in aqueous electrolyte solutions to calculate the density profiles and solution thermodynamics. It is found that the 3D-IEs provide a qualitative description of the density distributions of the solvent species when compared to MD results, but at a much reduced computational effort in comparison to MD simulations. The thermodynamics of the solvated systems are also qualitatively reproduced by the IE results. The findings of this work show the IEs to be a valuable tool for the study and prediction of
NASA Astrophysics Data System (ADS)
Wohletz, K. H.; Sheridan, M. F.; Brown, W. K.
1989-11-01
The assumption that distributions of mass versus size interval for fragmented materials fit the log normal distribution is empirically based and has historical roots in the late 19th century. Other often used distributions (e.g., Rosin-Rammler, Weibull) are also empirical and have the general form for mass per size interval: n(l) = klα exp (-lβ), where n(l) represents the number of particles of diameter l, l is the normalized particle diameter, and k, α, and β are constants. We describe and extend the sequential fragmentation distribution to include transport effects upon observed volcanic ash size distributions. The sequential fragmentation/transport (SFT) distribution is also of the above mathematical form, but it has a physical basis rather than empirical. The SFT model applies to a particle-mass distribution formed by a sequence of fragmentation (comminution) and transport (size sorting) events acting upon an initial mass m': n(x, m) = C ∫∫ n(x', m')p(ξ)dx' dm', where x' denotes spatial location along a linear axis, C is a constant, and integration is performed over distance from an origin to the sample location and mass limits from 0 to m. We show that the probability function that models the production of particles of different size from an initial mass and sorts that distribution, p(ξ), is related to mg, where g (noted as γ for fragmentation processes) is a free parameter that determines the location, breadth, and skewness of the distribution; g(γ) must be greater than -1, and it increases from that value as the distribution matures with greater number of sequential steps in the fragmentation or transport process; γ is expected to be near -1 for "sudden" fragmentation mechanisms such as single-event explosions and transport mechanisms that are functionally dependent upon particle mass. This free parameter will be more positive for evolved fragmentation mechanisms such as ball milling and complex transport processes such as saltation. The SFT
Dubois, D.F.; Hanssen, A.; Rose, H.A.; Russell, D.
1993-10-01
The predictions of strong Langmuir turbulence (SLT) theory are compared with radar observations of HF induced turbulence at Arecibo and Tromso. The altitude distribution of turbulence observed in the cold start experiments of Fejer et al. imply that the ionospheric electron density profile is modified by the induced turbulence. The preconditioned observations at Arecibo and the Tromso observations also appear to require a {open_quotes}disturbed{close_quotes} profile with several percent density fluctuations. With such density modifications postulated the authors conclude the SLT theory is in, at least, qualitative agreement with a large body of observations. Specifically SLT theory predicts, as part of a unified theory, and in distinction to the weak turbulence approximation, at least four unique physical signatures which can be compared to observations: (1) A caviton continuum plus free mode peak in the plasma line power spectrum near reflection altitude for Arecibo conditions. (2) A truncated decay-cascade spectrum at lower altitudes (or densities). (3) A continuous spectrum underlying the decay-cascade spectrum. (4) A zero frequency feature in the ion line power spectrum directly related to caviton dynamics. The authors find that there is sufficient ponderomotive pressure due to the Airy-layered, induced Langmuir turbulence, to modify the electron density profile in a manner consistent with the time behavior of unpreconditioned Arecibo observations. 59 refs., 14 figs.
NASA Technical Reports Server (NTRS)
Edmonds, Larry D.
1987-01-01
The steady state current distribution in a three dimensional integrated circuit is presented. A device physics approach, based on a perturbation method rather than an equivalent lumped circuit approach, is used. The perturbation method allows the various currents to be expressed in terms of elementary solutions which are solutions to very simple boundary value problems. A Simple Steady State Theory is the subtitle because the most obvious limitation of the present version of the analysis is that all depletion region boundary surfaces are treated as equipotential surfaces. This may be an adequate approximation in some applications but it is an obvious weakness in the theory when applied to latched states. Examples that illustrate the use of these analytical methods are not given because they will be presented in detail in the future.
Typical versus averaged overlap distribution in spin glasses: Evidence for droplet scaling theory
NASA Astrophysics Data System (ADS)
Monthus, Cécile; Garel, Thomas
2013-10-01
We consider the statistical properties over disordered samples (J) of the overlap distribution PJ(q) which plays the role of an order parameter in spin glasses. We show that near zero temperature (i) the typical overlap distribution is exponentially small in the central region of -1distribution PJ(q)¯ is nontypical and dominated by rare anomalous samples. Similar statements hold for the cumulative overlap distribution IJ(q0)≡∫0q0dqPJ(q). These results are derived explicitly for the spherical mean-field model with θ=1/3, ϕ(q)=1-q2, and the random variable v corresponds to the rescaled difference between the two largest eigenvalues of Gaussian orthogonal ensemble random matrices. Then we compare numerically the typical and averaged overlap distributions for the long-ranged one-dimensional Ising spin glass with random couplings decaying as J(r)∝r-σ for various values of the exponent σ, corresponding to various droplet exponents θ(σ), and for the mean-field Sherrington-Kirkpatrick model (corresponding formally to the σ=0 limit of the previous model). Our conclusion is that future studies on spin glasses should measure the typical values of the overlap distribution Ptyp(q) or of the cumulative overlap distribution Ityp(q0)=elnIJ(q0)¯ to obtain clearer conclusions on the nature of the spin-glass phase.
A theory of the cancer age-specific incidence data based on extreme value distributions
NASA Astrophysics Data System (ADS)
Soto-Ortiz, Luis; Brody, James P.
2012-03-01
The incidence of cancers varies with age, if normalized this is called the age-specific incidence. A mathematical model that describes this variation should provide a better understanding of how cancers develop. We suggest that the age-specific incidence should follow an extreme value distribution, based on three widely accepted assumptions: (1) a tumor develops from a single cell, (2) many potential tumor progenitor cells exist in a tissue, and (3) cancer is diagnosed when the first of these many potential tumor cells develops into a tumor. We tested this by comparing the predicted distribution to the age-specific incidence data for colon and prostate carcinomas collected by the Surveillance, Epidemiology and End Results network of 17 cancer registries. We found that colon carcinoma age-specific incidence data is consistent with an extreme value distribution, while prostate carcinomas age-specific incidence data generally follows the distribution. This model indicates that both colon and prostate carcinomas only occur in a subset of the population (22% for prostate and 13.5% for colon.) Because of their very general nature, extreme value distributions might be applicable to understanding other chronic human diseases.
Schroeder, J. W. R. Skiff, F.; Howes, G. G.; Kletzing, C. A.; Carter, T. A.; Dorfman, S.
2015-12-10
Wave propagation can be an accurate method for determining material properties. High frequency whistler mode waves (0.7 < ω/|Ω{sub ce}| < 1) in an overdense plasma (ω{sub pe} > |Ω{sub ce}|) are damped primarily by Doppler-shifted electron cyclotron resonance. A kinetic description of whistler mode propagation parallel to the background magnetic field shows that damping is proportional to the parallel electron distribution function. This property enables an experimental determination of the parallel electron distribution function using a measurement of whistler mode wave absorption. The whistler mode wave absorption diagnostic uses this technique on UCLA’s Large Plasma Device (LaPD) to measure the distribution of high energy electrons (5 − 10v{sub te}) with 0.1% precision. The accuracy is limited by systematic effects that need to be considered carefully. Ongoing research uses this diagnostic to investigate the effect of inertial Alfvén waves on the electron distribution function. Results presented here verify experimentally the linear effects of inertial Alfvén waves on the reduced electron distribution function, a necessary step before nonlinear physics can be tested. Ongoing experiments with the whistler mode wave absorption diagnostic are making progress toward the first direct detection of electrons nonlinearly accelerated by inertial Alfvén waves, a process believed to play an important role in auroral generation.
A physical theory of the living state: application to water and solute distribution.
Ling, G N
1988-06-01
This review begins with a summary of the disproof of the membrane-pump theory and the alternative theory of the living cell, the association-induction (AI) hypothesis. Being alive in the AI hypothesis represents the maintenance of a high (negative) energy-low entropy state in which the two major components K+ and water of the living cell are closely associated with the third major component of the living cells, proteins. K+ is adsorbed singly on beta- and gamma- carboxyl groups and the bulk of cell water in multilayers on the exposed NHCO groups of fully extended polypeptide chains of cell proteins. These adsorptions account for both the constancy of cell K+ and cell water per unit of cell proteins. ATP plays a key role in the maintenance of the cooperatively linked protein-ion-water assembly at the living state by its adsorption on key protein site and exercises the controlling influence through its strong inductive effects. Water polarized in multilayers demonstrates size-dependent exclusion of solutes, e.g., large (hydrated) Na+ is excluded from water in living cells or model systems while smaller urea that fits into the dynamic water structure is not excluded. The confirmation of the polarized multilayer theory of cell water by nuclear magnetic resonance (NMR), dielectric, neutron scattering, and other studies not only reverses the conventional belief of the existence of the cell water as normal liquid water; it also gives a new definition to colloids.
NASA Astrophysics Data System (ADS)
Lakowicz, Joseph R.; Szmacinski, Henryk; Johnson, Michael L.
1990-05-01
We examined the time -dependent donor decays of 2 - amino purine (2 -APU) , in the presence of increasing amounts of acceptor 2-aminobenzophenine (2-ABP). As the concentration of 2-ABP increases, the frequency-responses diverge from that predicted by Forster. The data were found to be consistent with modified Forster equations, but at this time we do not state that these modified expressions provide a correct molecular description of this donor-acceptor system. To the best of our knowledge this is the first paper which reports a failure of the Forster theory for randomly distributed donors and acceptors.
NASA Technical Reports Server (NTRS)
Isar, Aurelian
1995-01-01
The harmonic oscillator with dissipation is studied within the framework of the Lindblad theory for open quantum systems. By using the Wang-Uhlenbeck method, the Fokker-Planck equation, obtained from the master equation for the density operator, is solved for the Wigner distribution function, subject to either the Gaussian type or the delta-function type of initial conditions. The obtained Wigner functions are two-dimensional Gaussians with different widths. Then a closed expression for the density operator is extracted. The entropy of the system is subsequently calculated and its temporal behavior shows that this quantity relaxes to its equilibrium value.
THE LEBESGUE-STIELJES INTEGRAL AS APPLIED IN PROBABILITY DISTRIBUTION THEORY
bounded variation and Borel measureable functions are set forth in the introduction. Chapter 2 is concerned with establishing a one to one correspondence between LebesgueStieljes measures and certain equivalence classes of functions which are monotone non decreasing and continuous on the right. In Chapter 3 the Lebesgue-Stieljes Integral is defined and some of its properties are demonstrated. In Chapter 4 probability distribution function is defined and the notions in Chapters 2 and 3 are used to show that the Lebesgue-Stieljes integral of any probability distribution
Theory of Distribution Estimation of Hyperparameters in Markov Random Field Models
NASA Astrophysics Data System (ADS)
Sakamoto, Hirotaka; Nakanishi-Ohno, Yoshinori; Okada, Masato
2016-06-01
We investigated the performance of distribution estimation of hyperparameters in Markov random field models proposed by Nakanishi-Ohno et al., http://doi.org/10.1088/1751-8113/47/4/045001, J. Phys. A 47, 045001 (2014) when used to evaluate the confidence of data. We analytically calculated the configurational average, with respect to data, of the negative logarithm of the posterior distribution, which is called free energy based on an analogy with statistical mechanics. This configurational average of free energy shrinks as the amount of data increases. Our results theoretically confirm the numerical results from that previous study.
Distribution Theory for Glass's Estimator of Effect Size and Related Estimators.
ERIC Educational Resources Information Center
Hedges, Larry V.
1981-01-01
Glass's estimator of effect size, the sample mean difference divided by the sample standard deviation, is studied in the context of an explicit statistical model. The exact distribution of Glass's estimator is obtained and the estimator is shown to have a small sample bias. Alternatives are proposed and discussed. (Author/JKS)
Limit Distribution Theory for Maximum Likelihood Estimation of a Log-Concave Density.
Balabdaoui, Fadoua; Rufibach, Kaspar; Wellner, Jon A
2009-06-01
We find limiting distributions of the nonparametric maximum likelihood estimator (MLE) of a log-concave density, i.e. a density of the form f(0) = exp varphi(0) where varphi(0) is a concave function on R. Existence, form, characterizations and uniform rates of convergence of the MLE are given by Rufibach (2006) and Dümbgen and Rufibach (2007). The characterization of the log-concave MLE in terms of distribution functions is the same (up to sign) as the characterization of the least squares estimator of a convex density on [0, infinity) as studied by Groeneboom, Jongbloed and Wellner (2001b). We use this connection to show that the limiting distributions of the MLE and its derivative are, under comparable smoothness assumptions, the same (up to sign) as in the convex density estimation problem. In particular, changing the smoothness assumptions of Groeneboom, Jongbloed and Wellner (2001b) slightly by allowing some higher derivatives to vanish at the point of interest, we find that the pointwise limiting distributions depend on the second and third derivatives at 0 of H(k), the "lower invelope" of an integrated Brownian motion process minus a drift term depending on the number of vanishing derivatives of varphi(0) = log f(0) at the point of interest. We also establish the limiting distribution of the resulting estimator of the mode M(f(0)) and establish a new local asymptotic minimax lower bound which shows the optimality of our mode estimator in terms of both rate of convergence and dependence of constants on population values.
NASA Technical Reports Server (NTRS)
Chulya, Abhisak; Mullen, Robert L.
1989-01-01
A linear finite strip plate element based on Mindlin-Reissner plate theory is developed. The analysis is suitable for both thin and thick plates. In the formulation, new transverse shear strains are introduced and assumed constant in each two-node linear strip. The element stiffness matrix is explicitly formulated for efficient computation and computer implementation. Numerical results showing the efficiency and predictive capability of the element for the analysis of plates are presented for different support and loading conditions and a wide range of thicknesses. No sign of shear locking is observed with the newly developed element.
Xu, Peng; Yao, Dezhong; Luo, Fen
2005-08-01
The registration method based on mutual information is currently a popular technique for the medical image registration, but the computation for the mutual information is complex and the registration speed is slow. In engineering process, a subsampling technique is taken to accelerate the registration speed at the cost of registration accuracy. In this paper a new method based on statistics sample theory is developed, which has both a higher speed and a higher accuracy as compared with the normal subsampling method, and the simulation results confirm the validity of the new method.
Estimation of variance distribution in three-dimensional reconstruction. I. Theory
NASA Astrophysics Data System (ADS)
Liu, Weiping; Frank, Joachim
1995-12-01
A theory is developed for estimating the three-dimensional (3-D) variance of a 3-D image reconstructed from projections by weighted backprojection. The theory is applicable for any data-collection schemes that produce partially redundant sampling of the angular space. The particular data collection considered here, the single-exposure random-conical scheme, is used for the reconstruction of macromolecules in electron microscopy. In this context, the purpose of the 3-D variance estimation is to detect and localize the conformational variability, to assess the significance of structural differences between two experimentally related 3-D images, and to assess the significance of local features in a 3-D image. The 3-D variance estimate of each reconstruction voxel is obtained by (i) the comparison of closest points on Fourier sections associated with difference projections, (ii) the comparison of neighbor projections in real space, or (iii) the comparison of projections with reprojections of the reconstruction. Copyright (c) 1995 Optical Society of America
Are galaxy distributions scale invariant? A perspective from dynamical systems theory
NASA Astrophysics Data System (ADS)
McCauley, J. L.
2002-06-01
Unless there is an evidence for fractal scaling with a single exponent over distances 0.1<=r<=100h-1Mpc, then the widely accepted notion of scale invariance of the correlation integral for 0.1<=r<=10h-1Mpc must be questioned. The attempt to extract a scaling exponent /ν from the correlation integral /n(r) by plotting /log(n(r)) vs. /log(r) is unreliable unless the underlying point set is approximately monofractal. The extraction of a spectrum of generalized dimensions νq from a plot of the correlation integral generating function Gn(q) by a similar procedure is probably an indication that Gn(q) does not scale at all. We explain these assertions after defining the term multifractal, mutually inconsistent definitions having been confused together in the cosmology literature. Part of this confusion is traced to the confusion in interpreting a measure-theoretic formula written down by Hentschel and Procaccia in the dynamical systems theory literature, while other errors follow from confusing together entirely different definitions of multifractal from two different schools of thought. Most important are serious errors in data analysis that follow from taking for granted a largest term approximation that is inevitably advertised in the literature on both fractals and dynamical systems theory.
Continuous-Time Discrete-Distribution Theory for Activity-Driven Networks
NASA Astrophysics Data System (ADS)
Zino, Lorenzo; Rizzo, Alessandro; Porfiri, Maurizio
2016-11-01
Activity-driven networks are a powerful paradigm to study epidemic spreading over time-varying networks. Despite significant advances, most of the current understanding relies on discrete-time computer simulations, in which each node is assigned an activity potential from a continuous distribution. Here, we establish a continuous-time discrete-distribution framework toward an analytical treatment of the epidemic spreading, from its onset to the endemic equilibrium. In the thermodynamic limit, we derive a nonlinear dynamical system to accurately model the epidemic spreading and leverage techniques from the fields of differential inclusions and adaptive estimation to inform short- and long-term predictions. We demonstrate our framework through the analysis of two real-world case studies, exemplifying different physical phenomena and time scales.
Continuous-Time Discrete-Distribution Theory for Activity-Driven Networks.
Zino, Lorenzo; Rizzo, Alessandro; Porfiri, Maurizio
2016-11-25
Activity-driven networks are a powerful paradigm to study epidemic spreading over time-varying networks. Despite significant advances, most of the current understanding relies on discrete-time computer simulations, in which each node is assigned an activity potential from a continuous distribution. Here, we establish a continuous-time discrete-distribution framework toward an analytical treatment of the epidemic spreading, from its onset to the endemic equilibrium. In the thermodynamic limit, we derive a nonlinear dynamical system to accurately model the epidemic spreading and leverage techniques from the fields of differential inclusions and adaptive estimation to inform short- and long-term predictions. We demonstrate our framework through the analysis of two real-world case studies, exemplifying different physical phenomena and time scales.
Ling, G N; Niu, Z; Ochsenfeld, M
1993-01-01
We determined the equilibrium distribution of twenty-one nonmetabolized nonelectrolytes in frog muscle cells. In all cases, plots of the equilibrium intracellular concentrations of a solute in the cell water against the external concentrations of the solute yielded straight lines in agreement with the prediction of such a rectilinear plot by the polarized multilayer (PM) theory. The slopes of these straight lines yield the equilibrium distribution coefficients or q-value of that solute. It was shown that, again in agreement with the PM theory, the q-values of fourteen nonelectrolytes vary with the molecular volumes of the nonelectrolytes, obeying the "size rule", i.e., the larger the solute, the lower its q-value. The q-values of the remaining seven nonelectrolytes also decrease with their molecular volumes but on a separate curve. These q-value vs. molecular volume plots (q-v plots) show strong resemblance to similar q-v plots of solutes in dialysis sacs containing proteins and polymers assuming the fully-extended conformation (extrovert models) but no, or only weak, resemblance to q-v plots of solutions containing native globular proteins (introvert models). These findings also support the PM theory, according to which some protein(s) pervasively present in cells are in the fully-extended conformation; and that these fully extended cell protein(s) polarize(s) in multilayers all or virtually all cell water. The relationship between the q-values of the nonelectrolytes and the solutes' respective molecular volume are described by two sets of theoretical curves, calculated from an equation introduced in the preceding paper. Both curves were computed on the basis of the same exclusion intensity (Uvp = 126 cal/mole). This factor measures the extra water-to-water interaction of the polarized water which acts to keep solute out of the cell water in degree according to the size of the solute. The two curves are computed on the basis of two different values of U(s), which
Application of wavelet theory to power distribution systems for fault detection
Momoh, J.; Rizy, D.T.
1996-03-01
In this paper an investigation of the wavelet transform as a means of creating a feature extractor for Artificial Neural Network (ANN) training is presented. The study includes a teresstrial-based 3 phase delta power distribution system. Faults were injected into the system and data was obtained from experimentation. Graphical representations of the feature extractors obtained in the time domain, the frequency domain and the wavelet domain are presented to ascertain the superiority of the wavelet ``reform feature extractor.
Judy, M M; Summerour, V; LeConey, T; Roa, R L; Templeton, G H
1982-01-01
A theoretical discussion is presented that describes the diffraction on monochromatic light by a three-dimensional sarcomere array having the following properties. The basic repetitive diffracting unit is the sarcomere. The contiguous arrangement of physically attached serial sarcomeres in the myofibril is contained within the model so that relative position of sarcomeres depend upon the lengths of intervening ones. Sarcomere length is described by a distribution function. This function may be discrete or continuous and contain one or more subpopulations. Two arrangements of sarcomeres are considered: (a) when sarcomeres of different lengths are arranged randomly in myofibrils the amplitude and width of mth order (m greater than or equal to 1) peaks and associated secondary diffraction maxima decrease and increase monotonically, respectively, as the standard deviation of the length distribution increases. No subpeaks are present regardless of the number of subpopulations within the distribution function. This behavior is shown to follow from the dependence of sarcomere position on the length of intervening sarcomeres. (b) When sarcomeres belonging to the same length subpopulation are arranged in serial contiguous fashion to form domains and more than one length subpopulation is present, then mth order diffraction peaks split to form subpeaks. The theoretical basis for this behavior is developed for the first time and may explain the subpeaks evident in diffraction patterns from cardiac and skeletal muscle. PMID:7059651
The complete two-loop integrated jet thrust distribution in soft-collinear effective theory
von Manteuffel, Andreas; Schabinger, Robert M.; Zhu, Hua Xing
2014-03-01
In this work, we complete the calculation of the soft part of the two-loop integrated jet thrust distribution in e+e- annihilation. This jet mass observable is based on the thrust cone jet algorithm, which involves a veto scale for out-of-jet radiation. The previously uncomputed part of our result depends in a complicated way on the jet cone size, r, and at intermediate stages of the calculation we actually encounter a new class of multiple polylogarithms. We employ an extension of the coproduct calculus to systematically exploit functional relations and represent our results concisely. In contrast to the individual contributions, the sum of all global terms can be expressed in terms of classical polylogarithms. Our explicit two-loop calculation enables us to clarify the small r picture discussed in earlier work. In particular, we show that the resummation of the logarithms of r that appear in the previously uncomputed part of the two-loop integrated jet thrust distribution is inextricably linked to the resummation of the non-global logarithms. Furthermore, we find that the logarithms of r which cannot be absorbed into the non-global logarithms in the way advocated in earlier work have coefficients fixed by the two-loop cusp anomalous dimension. We also show that in many cases one can straightforwardly predict potentially large logarithmic contributions to the integrated jet thrust distribution at L loops by making use of analogous contributions to the simpler integrated hemisphere soft function.
Davis, Joe M; Arriaga, Edgar A
2010-01-01
The separation of organelles by capillary electrophoresis (CE) produces large numbers of narrow peaks, which commonly are assumed to originate from single particles. In this paper, we show this is not always true. Here, we use established methods to partition simulated and real organelle CEs into regions of constant peak density and then use statistical-overlap theory to calculate the number of peaks (single particles) in each region. The only required measurements are the number of observed peaks (maxima) and peak standard deviation in the regions and the durations of the regions. Theory is developed for the precision of the estimated peak number and the threshold saturation above which the calculation is not advisable due to fluctuation of peak numbers. Theory shows that the relative precision is good when the saturation lies between 0.2 and 1.0 and is optimal when the saturation is slightly greater than 0.5. It also shows the threshold saturation depends on the peak standard deviation divided by the region's duration. The accuracy and precision of peak numbers estimated in different regions of organelle CEs are verified by computer simulations having both constant and nonuniform peak densities. The estimates are accurate to 6%. The estimated peak numbers in different regions are used to calculate migration-time and electrophoretic-mobility distributions. These distributions are less biased by peak overlap than ones determined by counting maxima and provide more correct measures of the organelle properties. The procedure is applied to a mitochondrial CE, in which over 20% of peaks are hidden by peak overlap.
NASA Technical Reports Server (NTRS)
Mingori, D. L.; Gibson, J. S.; Blelloch, P.; Adamian, A.
1985-01-01
The methods presented are based on results from infinite dimensional control theory, but they can be described and used in a finite dimensional context. This blend leads to an approach which employs powerful ideas on convergence, and is also quite practical for systems of realistic complexity. Appropriate reduced order models are generated simultaneously with the development of the compensator. The required models change as a function of changes in the performance demanded, sensor and actuator location, inherent damping, disturbances, etc. Thus they are driven by the control and estimation problems at hand. The compensators which emerge are very close to the ideal compensators which would be obtained with a very large order model. However, some simplification is frequently possible. The method of balanced realizations was found to be effective for this purpose.
Investigation of the stress distribution around a mode 1 crack with a novel strain gradient theory
NASA Astrophysics Data System (ADS)
Lederer, M.; Khatibi, G.
2017-01-01
Stress concentrations at the tip of a sharp crack have extensively been investigated in the past century. According to the calculations of Inglis, the stress ahead of a mode 1 crack shows the characteristics of a singularity. This solution is exact in the framework of linear elastic fracture mechanics (LEFM). From the viewpoint of multiscale modelling, however, it is evident that the stress at the tip of a stable crack cannot be infinite, because the strengths of atomic bonds are finite. In order to prevent the problem of this singularity, a new version of strain gradient elasticity is employed here. This theory is implemented in the commercial FEM code ABAQUS through user subroutine UEL. Convergence of the model is proved through consecutive mesh refinement. In consequence, the stresses ahead of a mode 1 crack become finite. Furthermore, the model predicts a size effect in the sense “smaller is stronger”.
Particle distribution functions in modulation theory. [for cosmic rays in solar wind
NASA Technical Reports Server (NTRS)
Forman, M. A.; Fisk, L. A.; Axford, W. I.
1974-01-01
Development of a simple formulation of the cosmic ray modulation problem which involves the use of the omnidirectional part of the distribution function in phase space, and the magnitude of the momentum or the rigidity. It is shown that, by employing the proposed formulation, the Compton-Getting factor is greatly simplified, and the well-known force-field equation is reduced to a one-dimensional Vlasov equation. In addition, another Vlasov equation can be written for the very low energy galactic particles which are convected by the solar wind.
Munaò, Gianmarco; Costa, Dino; Caccamo, Carlo
2016-10-19
Inspired by significant improvements obtained for the performances of the polymer reference interaction site model (PRISM) theory of the fluid phase when coupled with 'molecular closures' (Schweizer and Yethiraj 1993 J. Chem. Phys. 98 9053), we exploit a matrix generalization of this concept, suitable for the more general RISM framework. We report a preliminary test of the formalism, as applied to prototype square-well homonuclear diatomics. As for the structure, comparison with Monte Carlo shows that molecular closures are slightly more predictive than their 'atomic' counterparts, and thermodynamic properties are equally accurate. We also devise an application of molecular closures to models interacting via continuous, soft-core potentials, by using well established prescriptions in liquid state perturbation theories. In the case of Lennard-Jones dimers, our scheme definitely improves over the atomic one, providing semi-quantitative structural results, and quite good estimates of internal energy, pressure and phase coexistence. Our finding paves the way to a systematic employment of molecular closures within the RISM framework to be applied to more complex systems, such as molecules constituted by several non-equivalent interaction sites.
NASA Astrophysics Data System (ADS)
Munaò, Gianmarco; Costa, Dino; Caccamo, Carlo
2016-10-01
Inspired by significant improvements obtained for the performances of the polymer reference interaction site model (PRISM) theory of the fluid phase when coupled with ‘molecular closures’ (Schweizer and Yethiraj 1993 J. Chem. Phys. 98 9053), we exploit a matrix generalization of this concept, suitable for the more general RISM framework. We report a preliminary test of the formalism, as applied to prototype square-well homonuclear diatomics. As for the structure, comparison with Monte Carlo shows that molecular closures are slightly more predictive than their ‘atomic’ counterparts, and thermodynamic properties are equally accurate. We also devise an application of molecular closures to models interacting via continuous, soft-core potentials, by using well established prescriptions in liquid state perturbation theories. In the case of Lennard-Jones dimers, our scheme definitely improves over the atomic one, providing semi-quantitative structural results, and quite good estimates of internal energy, pressure and phase coexistence. Our finding paves the way to a systematic employment of molecular closures within the RISM framework to be applied to more complex systems, such as molecules constituted by several non-equivalent interaction sites.
Dekkers, Petrus J; Friedlander, Sheldon K
2002-04-15
Gas-phase synthesis of fine solid particles leads to fractal-like structures whose transport and light scattering properties differ from those of their spherical counterparts. Self-preserving size distribution theory provides a useful methodology for analyzing the asymptotic behavior of such systems. Apparent inconsistencies in previous treatments of the self-preserving size distributions in the free molecule regime are resolved. Integro-differential equations for fractal-like particles in the continuum and near continuum regimes are derived and used to calculate the self-preserving and quasi-self-preserving size distributions for agglomerates formed by Brownian coagulation. The results for the limiting case (the continuum regime) were compared with the results of other authors. For these cases the finite difference method was in good in agreement with previous calculations in the continuum regime. A new analysis of aerosol agglomeration for the entire Knudsen number range was developed and compared with a monodisperse model; Higher agglomeration rates were found for lower fractal dimensions, as expected from previous studies. Effects of fractal dimension, pressure, volume loading and temperature on agglomerate growth were investigated. The agglomeration rate can be reduced by decreasing volumetric loading or by increasing the pressure. In laminar flow, an increase in pressure can be used to control particle growth and polydispersity. For D(f)=2, an increase in pressure from 1 to 4 bar reduces the collision radius by about 30%. Varying the temperature has a much smaller effect on agglomerate coagulation.
Polyakov, Evgeny A; Vorontsov-Velyaminov, Pavel N
2014-08-28
Properties of ferrofluid bilayer (modeled as a system of two planar layers separated by a distance h and each layer carrying a soft sphere dipolar liquid) are calculated in the framework of inhomogeneous Ornstein-Zernike equations with reference hypernetted chain closure (RHNC). The bridge functions are taken from a soft sphere (1/r(12)) reference system in the pressure-consistent closure approximation. In order to make the RHNC problem tractable, the angular dependence of the correlation functions is expanded into special orthogonal polynomials according to Lado. The resulting equations are solved using the Newton-GRMES algorithm as implemented in the public-domain solver NITSOL. Orientational densities and pair distribution functions of dipoles are compared with Monte Carlo simulation results. A numerical algorithm for the Fourier-Hankel transform of any positive integer order on a uniform grid is presented.
NASA Astrophysics Data System (ADS)
Regnier, D.; Dubray, N.; Schunck, N.; Verrière, M.
2016-05-01
Background: Accurate knowledge of fission fragment yields is an essential ingredient of numerous applications ranging from the formation of elements in the r process to fuel cycle optimization for nuclear energy. The need for a predictive theory applicable where no data are available, together with the variety of potential applications, is an incentive to develop a fully microscopic approach to fission dynamics. Purpose: In this work, we calculate the pre-neutron emission charge and mass distributions of the fission fragments formed in the neutron-induced fission of 239Pu using a microscopic method based on nuclear density functional theory (DFT). Methods: Our theoretical framework is the nuclear energy density functional (EDF) method, where large-amplitude collective motion is treated adiabatically by using the time-dependent generator coordinate method (TDGCM) under the Gaussian overlap approximation (GOA). In practice, the TDGCM is implemented in two steps. First, a series of constrained EDF calculations map the configuration and potential-energy landscape of the fissioning system for a small set of collective variables (in this work, the axial quadrupole and octupole moments of the nucleus). Then, nuclear dynamics is modeled by propagating a collective wave packet on the potential-energy surface. Fission fragment distributions are extracted from the flux of the collective wave packet through the scission line. Results: We find that the main characteristics of the fission charge and mass distributions can be well reproduced by existing energy functionals even in two-dimensional collective spaces. Theory and experiment agree typically within two mass units for the position of the asymmetric peak. As expected, calculations are sensitive to the structure of the initial state and the prescription for the collective inertia. We emphasize that results are also sensitive to the continuity of the collective landscape near scission. Conclusions: Our analysis confirms
NASA Technical Reports Server (NTRS)
Morgenthaler, George W.
1989-01-01
The ability to launch-on-time and to send payloads into space has progressed dramatically since the days of the earliest missile and space programs. Causes for delay during launch, i.e., unplanned 'holds', are attributable to several sources: weather, range activities, vehicle conditions, human performance, etc. Recent developments in space program, particularly the need for highly reliable logistic support of space construction and the subsequent planned operation of space stations, large unmanned space structures, lunar and Mars bases, and the necessity of providing 'guaranteed' commercial launches have placed increased emphasis on understanding and mastering every aspect of launch vehicle operations. The Center of Space Construction has acquired historical launch vehicle data and is applying these data to the analysis of space launch vehicle logistic support of space construction. This analysis will include development of a better understanding of launch-on-time capability and simulation of required support systems for vehicle assembly and launch which are necessary to support national space program construction schedules. In this paper, the author presents actual launch data on unscheduled 'hold' distributions of various launch vehicles. The data have been supplied by industrial associate companies of the Center for Space Construction. The paper seeks to determine suitable probability models which describe these historical data and that can be used for several purposes such as: inputs to broader simulations of launch vehicle logistic space construction support processes and the determination of which launch operations sources cause the majority of the unscheduled 'holds', and hence to suggest changes which might improve launch-on-time. In particular, the paper investigates the ability of a compound distribution probability model to fit actual data, versus alternative models, and recommends the most productive avenues for future statistical work.
NASA Astrophysics Data System (ADS)
Piasecki, Alison; Sessions, Alex; Peterson, Brian; Eiler, John
2016-10-01
Many previous studies have examined abundances of deuterium (D) and 13C within small organic molecules. Recent advances in analytical instrumentation add the abilities to measure site-specific and multiply substituted isotopologues of natural organics. Here we perform first-principles calculations of the equilibrium distributions of 13C and D in the volatile alkanes (including both single and multiple substitutions), as a guide to the interpretation of current measurements and as a basis for anticipating isotope effects that might be examined with future analytical techniques. The models we present illustrate several common themes of the isotopic structures of the small alkanes, including; temperature dependent enrichment of clumped isotope species, with amplitudes in the order D-D > 13C-D > 13C-13C; similarity in strength of such clumped isotope effects between different molecules (e.g., 13C-D clumping is ∼5‰ enriched at 300 K in methane, ethane and propane); a ∼10× contrast between the amplitudes of stronger adjacent substitution of two heavy isotopes vs. weaker non-adjacent substitution; temperature-dependent site-specific fractionation of D and 13C into interior positions of molecules relative to terminal methyl groups; and a relatively simple additive effect to the overall amplitude of enrichment when clumped and site specific effects combine in the same isotopologue. We suggest that the most promising tools suggested by our results are isotopic thermometers based on site-specific distribution of deuterium, which exhibits strong (∼100‰), highly temperature dependent fractionation between methyl groups and methylene carbon positions in propane (and likely other larger n-alkanes).
ERIC Educational Resources Information Center
Bowers, Wayne A.
This monograph was written for the Conference of the New Instructional Materials in Physics, held at the University of Washington in summer, 1965. It is intended for students who have had an introductory college physics course. It seeks to provide an introduction to the idea of distributions in general, and to some aspects of the subject in…
Theories of Simplification and Scaling of Spatially Distributed Processes. Chapter 12
NASA Technical Reports Server (NTRS)
Levin, Simon A.; Pacala, Stephen W.
1997-01-01
The problem of scaling is at the heart of ecological theory, the essence of understanding and of the development of a predictive capability. The description of any system depends on the spatial, temporal, and organizational perspective chosen; hence it is essential to understand not only how patterns and dynamics vary with scale, but also how patterns at one scale are manifestations of processes operating at other scales. Evolution has shaped the characteristics of species in ways that result in scale displacement: Each species experiences the environment at its own unique set of spatial and temporal scales and interfaces the biota through unique assemblages of phenotypes. In this way, coexistence becomes possible, and biodiversity is enhanced. By averaging over space, time, and biological interactions, a genotype filters variation at fine scales and selects the arena in which it will face the vicissitudes of nature. Variation at finer scales is then noise, of minor importance to the survival and dynamics of the species, and consequently of minor importance in any attempt at description. In attempting to model ecological interactions in space, contributors throughout this book have struggled with a trade-off between simplification and "realistic" complexity and detail. Although the challenge of simplification is widely recognized in ecology, less appreciated is the intertwining of scaling questions and scaling laws with the process of simplification. In the context of this chapter simplification will in general mean the use of spatial or ensemble means and low-order moments to capture more detailed interactions by integrating over given areas. In this way, one can derive descriptions of the system at different spatial scales, which provides the essentials for the extraction of scaling laws by examination of how system properties vary with scale.
Comparing ligo merger rate observations with theory: distribution of star-forming conditions
Belczynski, Kryzysztof; Kopparapu, R; O' Shaughnessy, R
2008-01-01
Within the next decade, ground based gravitational wave detectors are in principle capable of determining the compact object merger rate per unit volume of the local universe to better than 20% with more than 30 detections. Though these measurements can constrain our models of stellar, binary, and cluster evolution in the nearby present-day and ancient universe, we argue that the universe is sufficiently heterogeneous (in age and metallicity distribution at least) and that merger rates predicted by these models can be sufficiently sensitive to those heterogeneities so that a fair comparison of models per unit similar star forming mass necessarily introduces at least an additional 30%--50% systematic error into any constraints on compact binary evolution models. Without adding new electromagnetic constraints on massive binary evolution or relying on more information from each merger (e.g. , binary masses and spins), as few as the {approx_equal}5 merger detections could exhaust the information available in a naive comparison to merger rate predictions. As a concrete example immediately relevant to analysis of initial and enhanced LIGO results, we use a nearby-universe catalog to demonstrate that no one tracer of stellar content can be consistently used to constrain merger rates without introducing a systematic error of order 0(30%) at 90% confidence (depending on the type of binary involved). For example, though binary black holes typically take many Gyr to merge, binary neutron stars often merge rapidly; different tracers of stellar content are required for these two types. More generally, we argue that theoretical binary evolution can depend sufficiently sensitively on star-forming conditions -- even assuming no uncertainty in binary evolution model -- that the distribution of star forming conditions must be incorporated to reduce the systematic error in merger rate predictions below roughly 40%. We emphasize that the degree of sensitivity to star
NASA Astrophysics Data System (ADS)
Freifelder, R.; Prakash, M.; Alexander, John M.
1986-02-01
We examine the application of transition-state theory for fission-fragment angular distributions to composite nuclei near the limits of stability. The possible roles of saddle-point and scission-point configurations are explored. For many heavy-ion reactions that involve large angular momenta, the observed anisotropies are between the predictions of the saddle-point and scisson-point models. Empirical correlations are shown between the effective moments of inertia and the spin and {Z 2}/{A} of the compound nucleus. These correlations provide evidence for a class of transition-state nuclei intermediate between saddle- and scission-point configurations. An important indication of these patterns is that the speed of collective deformation toward fission may well be slow enough to allow for statistical equilibrium in the tilting mode even for configurations well beyond the saddle point.
Kinetic theory of phase space plateaux in a non-thermal energetic particle distribution
Eriksson, F. Nyqvist, R. M.; Lilley, M. K.
2015-09-15
The transformation of kinetically unstable plasma eigenmodes into hole-clump pairs with temporally evolving carrier frequencies was recently attributed to the emergence of an intermediate stage in the mode evolution cycle, that of an unmodulated plateau in the phase space distribution of fast particles. The role of the plateau as the hole-clump breeding ground is further substantiated in this article via consideration of its linear and nonlinear stability in the presence of fast particle collisions and sources, which are known to affect the production rates and subsequent frequency sweeping of holes and clumps. In particular, collisional relaxation, as mediated by e.g. velocity space diffusion or even simple Krook-type collisions, is found to inhibit hole-clump generation and detachment from the plateau, as it should. On the other hand, slowing down of the fast particles turns out to have an asymmetrically destabilizing/stabilizing effect, which explains the well-known result that collisional drag enhances holes and their sweeping rates but suppresses clumps. It is further demonstrated that relaxation of the plateau edge gradients has only a minor quantitative effect and does not change the plateau stability qualitatively, unless the edge region extends far into the plateau shelf and the corresponding Landau pole needs to be taken into account.
Hopkins, Paul; Fortini, Andrea; Archer, Andrew J; Schmidt, Matthias
2010-12-14
We describe a test particle approach based on dynamical density functional theory (DDFT) for studying the correlated time evolution of the particles that constitute a fluid. Our theory provides a means of calculating the van Hove distribution function by treating its self and distinct parts as the two components of a binary fluid mixture, with the "self " component having only one particle, the "distinct" component consisting of all the other particles, and using DDFT to calculate the time evolution of the density profiles for the two components. We apply this approach to a bulk fluid of Brownian hard spheres and compare to results for the van Hove function and the intermediate scattering function from Brownian dynamics computer simulations. We find good agreement at low and intermediate densities using the very simple Ramakrishnan-Yussouff [Phys. Rev. B 19, 2775 (1979)] approximation for the excess free energy functional. Since the DDFT is based on the equilibrium Helmholtz free energy functional, we can probe a free energy landscape that underlies the dynamics. Within the mean-field approximation we find that as the particle density increases, this landscape develops a minimum, while an exact treatment of a model confined situation shows that for an ergodic fluid this landscape should be monotonic. We discuss possible implications for slow, glassy, and arrested dynamics at high densities.
Benjamin A. Frandsen; Brunelli, Michela; Page, Katharine; ...
2016-05-11
Here, we present a temperature-dependent atomic and magnetic pair distribution function (PDF) analysis of neutron total scattering measurements of antiferromagnetic MnO, an archetypal strongly correlated transition-metal oxide. The known antiferromagnetic ground-state structure fits the low-temperature data closely with refined parameters that agree with conventional techniques, confirming the reliability of the newly developed magnetic PDF method. The measurements performed in the paramagnetic phase reveal significant short-range magnetic correlations on a ~1 nm length scale that differ substantially from the low-temperature long-range spin arrangement. Ab initio calculations using a self-interaction-corrected local spin density approximation of density functional theory predict magnetic interactions dominatedmore » by Anderson superexchange and reproduce the measured short-range magnetic correlations to a high degree of accuracy. Further calculations simulating an additional contribution from a direct exchange interaction show much worse agreement with the data. Furthermore, the Anderson superexchange model for MnO is thus verified by experimentation and confirmed by ab initio theory.« less
NASA Astrophysics Data System (ADS)
Hüttner, Bernd; Rohr, Gernot C.
1998-04-01
The interaction of short laser pulses with metals is described in terms of a new model involving a generalised nonlocal heat flow in time. The resulting system of coupled differential equations contains additional terms that originate in the thermal inertia of the electron subsystem. They are connected to the time derivative of both the laser intensity and the coupling of the electrons to the phonons. After briefly discussing the importance of the coefficient of heat exchange and of the different contributions to its main parts, the electron-phonon coupling and the average of the squared phonon frequencies, we present snap-shot-like calculations of the spatial temperature distribution along the z-axis for Al, Au, Pb and Nb for different intensities but fixed pulse duration τL=250 fs. In addition, the electron and phonon temperatures inside a thin Au film are studied in detail. Our results are compared to those arising from a standard two temperature model (TTM) and those of the conventional theory. While the traditional theory becomes invalid in most cases at least in the ps-range the differences between our approach and the TTM become the more pronounced the smaller the coefficient of heat exchange.
NASA Astrophysics Data System (ADS)
Frandsen, Benjamin A.; Brunelli, Michela; Page, Katharine; Uemura, Yasutomo J.; Staunton, Julie B.; Billinge, Simon J. L.
2016-05-01
We present a temperature-dependent atomic and magnetic pair distribution function (PDF) analysis of neutron total scattering measurements of antiferromagnetic MnO, an archetypal strongly correlated transition-metal oxide. The known antiferromagnetic ground-state structure fits the low-temperature data closely with refined parameters that agree with conventional techniques, confirming the reliability of the newly developed magnetic PDF method. The measurements performed in the paramagnetic phase reveal significant short-range magnetic correlations on a ˜1 nm length scale that differ substantially from the low-temperature long-range spin arrangement. Ab initio calculations using a self-interaction-corrected local spin density approximation of density functional theory predict magnetic interactions dominated by Anderson superexchange and reproduce the measured short-range magnetic correlations to a high degree of accuracy. Further calculations simulating an additional contribution from a direct exchange interaction show much worse agreement with the data. The Anderson superexchange model for MnO is thus verified by experimentation and confirmed by ab initio theory.
Huggins, David J
2012-11-21
The structures of biomolecules and the strengths of association between them depend critically on interactions with water molecules. Thus, understanding these interactions is a prerequisite for understanding the structure and function of all biomolecules. Inhomogeneous fluid solvation theory provides a framework to derive thermodynamic properties of individual water molecules from a statistical mechanical analysis. In this work, two biomolecules are analysed to probe the distribution and thermodynamics of surrounding water molecules. The great majority of hydration sites are predicted to contribute favourably to the total free energy with respect to bulk water, though hydration sites close to non-polar regions of the solute do not contribute significantly. Analysis of a biomolecule with a positively and negatively charged functional group predicts that a charged species perturbs the free energy of water molecules to a distance of approximately 6.0 Å. Interestingly, short simulations are found to provide converged predictions if samples are taken with sufficient frequency, a finding that has the potential to significantly reduce the required computational cost of such analysis. In addition, the predicted thermodynamic properties of hydration sites with the potential for direct hydrogen bonding interactions are found to disagree significantly for two different water models. This study provides important information on how inhomogeneous fluid solvation theory can be employed to understand the structures and intermolecular interactions of biomolecules.
Krieg, Daniel; Triesch, Jochen
2014-01-01
Long-term synaptic plasticity is fundamental to learning and network function. It has been studied under various induction protocols and depends on firing rates, membrane voltage, and precise timing of action potentials. These protocols show different facets of a common underlying mechanism but they are mostly modeled as distinct phenomena. Here, we show that all of these different dependencies can be explained from a single computational principle. The objective is a sparse distribution of excitatory synaptic strength, which may help to reduce metabolic costs associated with synaptic transmission. Based on this objective we derive a stochastic gradient ascent learning rule which is of differential-Hebbian type. It is formulated in biophysical quantities and can be related to current mechanistic theories of synaptic plasticity. The learning rule accounts for experimental findings from all major induction protocols and explains a classic phenomenon of metaplasticity. Furthermore, our model predicts the existence of metaplasticity for spike-timing-dependent plasticity Thus, we provide a theory of long-term synaptic plasticity that unifies different induction protocols and provides a connection between functional and mechanistic levels of description. PMID:24624080
X-ray-absorption spectroscopy and n-body distribution functions in condensed matter. I. Theory
NASA Astrophysics Data System (ADS)
Filipponi, Adriano; di Cicco, Andrea; Natoli, Calogero Renzo
1995-12-01
The general theoretical framework underlying the GNXAS multiple-scattering (MS) data-analysis method for x-ray absorption spectroscopy (XAS) is presented. The main approximations leading to the reduction of the many-body process in that of a photoelectron scattering in an effective potential are summarized. The methods available to expand the extended x-ray-absorption fine-structure χ(k) into physically meaningful terms are described. In particular, emphasis is given to the definition of the irreducible n-body signals γ(n) that can be calculated directly by means of linear combinations of continued fractions, or by using their respective multiple-scattering series. It is found that even for an infinite system the expansion of the χ(k) signal in terms of γ(n) has a better convergence rate than the MS series. Simple expressions for performing the configurational averages of the structural signals in the presence of thermal and structural disorder are derived. These can be used for the structural analysis of molecular, crystalline, or moderately disordered systems. It is shown that in the case of highly disordered systems the expansion in terms of the γ(n) signals is the natural framework for the interpretation of the XAS signal. General equations for the ensemble-averaged χ(k) signal as a function of a series of integrals over the n-body n>~2 distribution functions gn are provided and the possible use of advanced strategies for the inversion of the structural information is suggested.
Maruyama, Tomoyuki; Cheoun, Myung-Ki; Kajino, Toshitaka; Mathews, Grant J.
2016-03-26
We study pion production by proton synchrotron radiation in the presence of a strong magnetic field when the Landau numbers of the initial and final protons are n(i, f) similar to 10(4)-10(5). We find in our relativistic field theory calculations that the pion decay width depends only on the field strength parameter which previously was only conjectured based upon semi-classical arguments. Moreover, we also find new results that the decay width satisfies a robust scaling relation, and that the polar angular distribution of emitted pion momenta is very narrow and can be easily obtained. This scaling implies that one can infer the decay width in more realistic magnetic fields of 10(15) G, where n(i, f) similar to 10(12)-10(13), from the results for n(i, f) similar to 10(4)-10(5). The resultant pion intensity and angular distributions for realistic magnetic field strengths are presented and their physical implications discussed. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).
NASA Astrophysics Data System (ADS)
Fritzsche, Matthias; Kittel, Konstantin; Blankenburg, Alexander; Vajna, Sándor
2012-08-01
The focus of this paper is to present a method of multidisciplinary design optimisation based on the autogenetic design theory (ADT) that provides methods, which are partially implemented in the optimisation software described here. The main thesis of the ADT is that biological evolution and the process of developing products are mainly similar, i.e. procedures from biological evolution can be transferred into product development. In order to fulfil requirements and boundary conditions of any kind (that may change at any time), both biological evolution and product development look for appropriate solution possibilities in a certain area, and try to optimise those that are actually promising by varying parameters and combinations of these solutions. As the time necessary for multidisciplinary design optimisations is a critical aspect in product development, ways to distribute the optimisation process with the effective use of unused calculating capacity, can reduce the optimisation time drastically. Finally, a practical example shows how ADT methods and distributed optimising are applied to improve a product.
Maruyama, Tomoyuki; Cheoun, Myung-Ki; Kajino, Toshitaka; ...
2016-03-26
We study pion production by proton synchrotron radiation in the presence of a strong magnetic field when the Landau numbers of the initial and final protons are n(i, f) similar to 10(4)-10(5). We find in our relativistic field theory calculations that the pion decay width depends only on the field strength parameter which previously was only conjectured based upon semi-classical arguments. Moreover, we also find new results that the decay width satisfies a robust scaling relation, and that the polar angular distribution of emitted pion momenta is very narrow and can be easily obtained. This scaling implies that one canmore » infer the decay width in more realistic magnetic fields of 10(15) G, where n(i, f) similar to 10(12)-10(13), from the results for n(i, f) similar to 10(4)-10(5). The resultant pion intensity and angular distributions for realistic magnetic field strengths are presented and their physical implications discussed. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).« less
Saichev, A; Sornette, D
2005-05-01
Using the epidemic-type aftershock sequence (ETAS) branching model of triggered seismicity, we apply the formalism of generating probability functions to calculate exactly the average difference between the magnitude of a mainshock and the magnitude of its largest aftershock over all generations. This average magnitude difference is found empirically to be independent of the mainshock magnitude and equal to 1.2, a universal behavior known as Båth's law. Our theory shows that Båth's law holds only sufficiently close to the critical regime of the ETAS branching process. Allowing for error bars +/- 0.1 for Båth's constant value around 1.2, our exact analytical treatment of Båth's law provides new constraints on the productivity exponent alpha and the branching ratio n: 0.9 approximately < alpha < or =1. We propose a method for measuring alpha based on the predicted renormalization of the Gutenberg-Richter distribution of the magnitudes of the largest aftershock. We also introduce the "second Båth law for foreshocks:" the probability that a main earthquake turns out to be the foreshock does not depend on its magnitude rho.
NASA Astrophysics Data System (ADS)
Launey, K. D.; Sarbadhicary, S.; Dytrych, T.; Draayer, J. P.
2014-01-01
We present a program in C that employs spectral distribution theory for studies of characteristic properties of a many-particle quantum-mechanical system and the underlying few-body interaction. In particular, the program focuses on two-body nuclear interactions given in a JT-coupled harmonic oscillator basis and calculates correlation coefficients, a measure of similarity of any two interactions, as well as Hilbert-Schmidt norms specifying interaction strengths. An important feature of the program is its ability to identify the monopole part (centroid) of a 2-body interaction, as well as its 'density-dependent' one-body and two-body part, thereby providing key information on the evolution of shell gaps and binding energies for larger nuclear systems. As additional features, we provide statistical measures for 'density-dependent' interactions, as well as a mechanism to express an interaction in terms of two other interactions. This, in turn, allows one to identify, e.g., established features of the nuclear interaction (such as pairing correlations) within a general Hamiltonian. The program handles the radial degeneracy for 'density-dependent' one-body interactions and together with an efficient linked list data structure, facilitates studies of nuclear interactions in large model spaces that go beyond valence-shell applications.
NASA Technical Reports Server (NTRS)
Barger, R. L.
1975-01-01
The theory provides a direct method for resolving an airfoil into a lifting line and a thickness distribution as well as a means of synthesizing thickness and lift components into a resultant airfoil and computing its aerodynamic characteristics. Specific applications of the technique are discussed.
1979-01-01
ELECTE! Mg++ and K+ Distribution in Frog Muscle and Egg: B A Disproof of the Donnan Theory of Membrane B Equilibrium Applied to the Living Cells GILBERT...19107 J ABSTRACT 1. We studied the equilibrium distribution of Mg** in the form of chlo- ride and pulfate at two temperatures (5* and 25°C) in frog ...vicinity of 90 jmoles/g/ fresh muscle cells. 4. We observed a similar rectilinear distribution of Mg** in frog ovarian eggs. As in muscle tissues, no major
Kawamura, Hiroyuki; Tanaka, Kazuhiro
2010-06-01
The B-meson distribution amplitude (DA) is defined as the matrix element of a quark-antiquark bilocal light-cone operator in the heavy-quark effective theory, corresponding to a long-distance component in the factorization formula for exclusive B-meson decays. The evolution equation for the B-meson DA is governed by the cusp anomalous dimension as well as the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi-type anomalous dimension, and these anomalous dimensions give the ''quasilocal'' kernel in the coordinate-space representation. We show that this evolution equation can be solved analytically in the coordinate space, accomplishing the relevant Sudakov resummation at the next-to-leading logarithmic accuracy. The quasilocal nature leads to a quite simple form of our solution which determines the B-meson DA with a quark-antiquark light-cone separation t in terms of the DA at a lower renormalization scale {mu} with smaller interquark separations zt (z{<=}1). This formula allows us to present rigorous calculation of the B-meson DA at the factorization scale {approx}{radical}(m{sub b{Lambda}QCD}) for t less than {approx}1 GeV{sup -1}, using the recently obtained operator product expansion of the DA as the input at {mu}{approx}1 GeV. We also derive the master formula, which reexpresses the integrals of the DA at {mu}{approx}{radical}(m{sub b{Lambda}QCD}) for the factorization formula by the compact integrals of the DA at {mu}{approx}1 GeV.
NASA Astrophysics Data System (ADS)
Danesh-Yazdi, Mohammad; Foufoula-Georgiou, Efi; Karwan, Diana L.; Botter, Gianluca
2016-10-01
Climatic trends and anthropogenic changes in land cover and land use are impacting the hydrology and water quality of streams at the field, watershed, and regional scales in complex ways. In poorly drained agricultural landscapes, subsurface drainage systems have been successful in increasing crop productivity by removing excess soil moisture. However, their hydroecological consequences are still debated in view of the observed increased concentrations of nitrate, phosphorus, and pesticides in many streams, as well as altered runoff volumes and timing. In this study, we employ the recently developed theory of time-variant travel time distributions within the StorAge Selection function framework to quantify changes in water cycle dynamics resulting from the combined climate and land use changes. Our results from analysis of a subbasin in the Minnesota River Basin indicate a significant decrease in the mean travel time of water in the shallow subsurface layer during the growing season under current conditions compared to the pre-1970s conditions. We also find highly damped year-to-year fluctuations in the mean travel time, which we attribute to the "homogenization" of the hydrologic response due to artificial drainage. The dependence of the mean travel time on the spatial heterogeneity of some soil characteristics as well as on the basin scale is further explored via numerical experiments. Simulations indicate that the mean travel time is independent of scale for spatial scales larger than approximately 200 km2, suggesting that hydrologic data from larger basins may be used to infer the average of smaller-scale-driven changes in water cycle dynamics.
NASA Astrophysics Data System (ADS)
Kido, Kentaro; Kasahara, Kento; Yokogawa, Daisuke; Sato, Hirofumi
2015-07-01
In this study, we reported the development of a new quantum mechanics/molecular mechanics (QM/MM)-type framework to describe chemical processes in solution by combining standard molecular-orbital calculations with a three-dimensional formalism of integral equation theory for molecular liquids (multi-center molecular Ornstein-Zernike (MC-MOZ) method). The theoretical procedure is very similar to the 3D-reference interaction site model self-consistent field (RISM-SCF) approach. Since the MC-MOZ method is highly parallelized for computation, the present approach has the potential to be one of the most efficient procedures to treat chemical processes in solution. Benchmark tests to check the validity of this approach were performed for two solute (solute water and formaldehyde) systems and a simple SN2 reaction (Cl- + CH3Cl → ClCH3 + Cl-) in aqueous solution. The results for solute molecular properties and solvation structures obtained by the present approach were in reasonable agreement with those obtained by other hybrid frameworks and experiments. In particular, the results of the proposed approach are in excellent agreements with those of 3D-RISM-SCF.
Kido, Kentaro; Kasahara, Kento; Yokogawa, Daisuke; Sato, Hirofumi
2015-07-07
In this study, we reported the development of a new quantum mechanics/molecular mechanics (QM/MM)-type framework to describe chemical processes in solution by combining standard molecular-orbital calculations with a three-dimensional formalism of integral equation theory for molecular liquids (multi-center molecular Ornstein-Zernike (MC-MOZ) method). The theoretical procedure is very similar to the 3D-reference interaction site model self-consistent field (RISM-SCF) approach. Since the MC-MOZ method is highly parallelized for computation, the present approach has the potential to be one of the most efficient procedures to treat chemical processes in solution. Benchmark tests to check the validity of this approach were performed for two solute (solute water and formaldehyde) systems and a simple SN2 reaction (Cl(-) + CH3Cl → ClCH3 + Cl(-)) in aqueous solution. The results for solute molecular properties and solvation structures obtained by the present approach were in reasonable agreement with those obtained by other hybrid frameworks and experiments. In particular, the results of the proposed approach are in excellent agreements with those of 3D-RISM-SCF.
Kido, Kentaro; Kasahara, Kento; Yokogawa, Daisuke; Sato, Hirofumi
2015-07-07
In this study, we reported the development of a new quantum mechanics/molecular mechanics (QM/MM)-type framework to describe chemical processes in solution by combining standard molecular-orbital calculations with a three-dimensional formalism of integral equation theory for molecular liquids (multi-center molecular Ornstein–Zernike (MC-MOZ) method). The theoretical procedure is very similar to the 3D-reference interaction site model self-consistent field (RISM-SCF) approach. Since the MC-MOZ method is highly parallelized for computation, the present approach has the potential to be one of the most efficient procedures to treat chemical processes in solution. Benchmark tests to check the validity of this approach were performed for two solute (solute water and formaldehyde) systems and a simple S{sub N}2 reaction (Cl{sup −} + CH{sub 3}Cl → ClCH{sub 3} + Cl{sup −}) in aqueous solution. The results for solute molecular properties and solvation structures obtained by the present approach were in reasonable agreement with those obtained by other hybrid frameworks and experiments. In particular, the results of the proposed approach are in excellent agreements with those of 3D-RISM-SCF.
NASA Technical Reports Server (NTRS)
Samir, U.; Fontheim, E. G.
1981-01-01
Measurements of electron density, plasma potential, and mean ion mass from the Explorer 31 satellite, and measurements of ion current, plasma potential, and ion composition from the Atmosphere Explorer C satellite were used in a comparative study with Parker's theory regarding the charged particle distribution in the near wake of an ionospheric satellite (1976). It is shown that theory and experiment agree fairly well in the angle-of-attack range between 90 and 135 deg. In the maximum rarefaction zone (between 145 and 180 deg), however, the theoretical model overestimates the measured ion depletion by several orders of magnitude. A comparison between theory and the Explorer 31 electron measurements shows that the theory again overestimates the electron depletion. These discrepancies are mainly due to the use of a steady-state theory and a single ion equation (using a mean ion mass). Improved agreement between theory and experiment can be obtained by the use of the time-dependent Vlasov-Poisson equations with separate equations for the various ion species.
ERIC Educational Resources Information Center
Tian, Meng; Risku, Mika; Collin, Kaija
2016-01-01
This article provides a meta-analysis of research conducted on distributed leadership from 2002 to 2013. It continues the review of distributed leadership commissioned by the English National College for School Leadership (NCSL) ("Distributed Leadership: A Desk Study," Bennett et al., 2003), which identified two gaps in the research…
Product Distributions for Distributed Optimization. Chapter 1
NASA Technical Reports Server (NTRS)
Bieniawski, Stefan R.; Wolpert, David H.
2004-01-01
With connections to bounded rational game theory, information theory and statistical mechanics, Product Distribution (PD) theory provides a new framework for performing distributed optimization. Furthermore, PD theory extends and formalizes Collective Intelligence, thus connecting distributed optimization to distributed Reinforcement Learning (FU). This paper provides an overview of PD theory and details an algorithm for performing optimization derived from it. The approach is demonstrated on two unconstrained optimization problems, one with discrete variables and one with continuous variables. To highlight the connections between PD theory and distributed FU, the results are compared with those obtained using distributed reinforcement learning inspired optimization approaches. The inter-relationship of the techniques is discussed.
NASA Technical Reports Server (NTRS)
Joss, P. C.
1973-01-01
The statistical significance of anisotropies in the distribution of orbital orientations among the long-period and nearly parabolic comets is evaluated. It is suggested that these anisotropies are not the result of observational selection effects. A numerical model for the distribution of orbital orientations is constructed, based on Oort's theory of comet origin and the assumption that the observed anisotropies are caused by multiple planetary perturbations over the course of many perihelion passages. The model, which is restricted to comets with perihelion distances less than 0.3 AU, does not predict any significant anisotropies.
NASA Astrophysics Data System (ADS)
Jaynes, E. T.; Bretthorst, G. Larry
2003-04-01
Foreword; Preface; Part I. Principles and Elementary Applications: 1. Plausible reasoning; 2. The quantitative rules; 3. Elementary sampling theory; 4. Elementary hypothesis testing; 5. Queer uses for probability theory; 6. Elementary parameter estimation; 7. The central, Gaussian or normal distribution; 8. Sufficiency, ancillarity, and all that; 9. Repetitive experiments, probability and frequency; 10. Physics of 'random experiments'; Part II. Advanced Applications: 11. Discrete prior probabilities, the entropy principle; 12. Ignorance priors and transformation groups; 13. Decision theory: historical background; 14. Simple applications of decision theory; 15. Paradoxes of probability theory; 16. Orthodox methods: historical background; 17. Principles and pathology of orthodox statistics; 18. The Ap distribution and rule of succession; 19. Physical measurements; 20. Model comparison; 21. Outliers and robustness; 22. Introduction to communication theory; References; Appendix A. Other approaches to probability theory; Appendix B. Mathematical formalities and style; Appendix C. Convolutions and cumulants.
NASA Astrophysics Data System (ADS)
Peng, Bo; Yu, Yang-Xin
2009-10-01
The structural and thermodynamic properties for charge symmetric and asymmetric electrolytes as well as mixed electrolyte system inside a charged cylindrical nanopore are investigated using a partially perturbative density functional theory. The electrolytes are treated in the restricted primitive model and the internal surface of the cylindrical nanopore is considered to have a uniform charge density. The proposed theory is directly applicable to the arbitrary mixed electrolyte solution containing ions with the equal diameter and different valences. Large amount of simulation data for ion density distributions, separation factors, and exclusion coefficients are used to determine the range of validity of the partially perturbative density functional theory for monovalent and multivalent counterion systems. The proposed theory is found to be in good agreement with the simulations for both mono- and multivalent counterion systems. In contrast, the classical Poisson-Boltzmann equation only provides reasonable descriptions of monovalent counterion system at low bulk density, and is qualitatively and quantitatively wrong in the prediction for the multivalent counterion systems due to its neglect of the strong interionic correlations in these systems. The proposed density functional theory has also been applied to an electrolyte absorbed into a pore that is a model of the filter of a physiological calcium channel.
Clevenger, Shelly L; Navarro, Jordana N; Jasinski, Jana L
2016-09-01
This study examined the demographic and background characteristic differences between those arrested for child pornography (CP) possession (only), or CP production/distribution, or an attempted or completed sexual exploitation of a minor (SEM) that involved the Internet in some capacity within the context of self-control theory using data from the second wave of the National Juvenile Online Victimization Study (N-JOV2). Results indicate few demographic similarities, which thereby suggest these are largely heterogeneous groupings of individuals. Results also indicate CP producers/distributers engaged in a greater number of behaviors indicative of low self-control compared with CP possessors. Specifically, offenders arrested for CP production/distribution were more likely to have (a) had problems with drugs/alcohol at the time of the crime and (b) been previously violent. In contrast, the only indicator of low self-control that reached statistical significance for CP possessors was the previous use of violence. Moreover, in contrast to CP producers/distributers, full-time employment and marital status may be important factors to consider in the likelihood of arrest for CP possessors, which is congruent with the tenets of self-control theory.
NASA Technical Reports Server (NTRS)
Matthews, Clarence W
1953-01-01
An analysis is made of the effects of compressibility on the pressure coefficients about several bodies of revolution by comparing experimentally determined pressure coefficients with corresponding pressure coefficients calculated by the use of the linearized equations of compressible flow. The results show that the theoretical methods predict the subsonic pressure-coefficient changes over the central part of the body but do not predict the pressure-coefficient changes near the nose. Extrapolation of the linearized subsonic theory into the mixed subsonic-supersonic flow region fails to predict a rearward movement of the negative pressure-coefficient peak which occurs after the critical stream Mach number has been attained. Two equations developed from a consideration of the subsonic compressible flow about a prolate spheroid are shown to predict, approximately, the change with Mach number of the subsonic pressure coefficients for regular bodies of revolution of fineness ratio 6 or greater.
Regnier, D.; Dubray, N.; Schunck, N.; ...
2016-05-13
Here, accurate knowledge of fission fragment yields is an essential ingredient of numerous applications ranging from the formation of elements in the r process to fuel cycle optimization for nuclear energy. The need for a predictive theory applicable where no data are available, together with the variety of potential applications, is an incentive to develop a fully microscopic approach to fission dynamics.
NASA Technical Reports Server (NTRS)
Wang, Jai-Ching; Watring, Dale A.; Lehoczky, Sandor L.; Su, Ching-Hua; Gillies, Don; Szofran, Frank
1999-01-01
Infrared detector materials, such as Hg(1-x)Cd(x)Te, Hg(1-x)Zn(x)Te have energy gaps almost linearly proportional to its composition. Due to the wide separation of liquidus and solidus curves of their phase diagram, there are compositional segregations in both of axial and radial directions of these crystals grown in the Bridgman system unidirectionally with constant growth rate. It is important to understand the mechanisms which affect lateral segregation such that large uniform radial composition crystal is possible. Following Coriell, etc's treatment, we have developed a theory to study the effect of a curved melt-solid interface shape on the lateral composition distribution. The system is considered to be cylindrical system with azimuthal symmetric with a curved melt-solid interface shape which can be expressed as a linear combination of a series of Bessell's functions. The results show that melt-solid interface shape has a dominate effect on lateral composition distribution of these systems. For small values of b, the solute concentration at the melt-solid interface scales linearly with interface shape with a proportional constant of the product of b and (1 - k), where b = VR/D, with V as growth velocity, R as sample radius, D as diffusion constant and k as distribution constant. A detailed theory will be presented. A computer code has been developed and simulations have been performed and compared with experimental results. These will be published in another paper.
NASA Technical Reports Server (NTRS)
Wang, Jai-Ching; Watring, D.; Lehoczky. S. L.; Su, C. H.; Gillies, D.; Szofran, F.; Sha, Y. G.; Sha, Y. G.
1999-01-01
Infrared detected materials, such as Hg(1-x)Cd(x)Te, Hg(1-x)Zn(x)Te have energy gaps almost linearly proportional to their composition. Due to the wide separation of liquidus and solidus curves of their phase diagram, there are compositional segregation in both of the axial and radial directions of these crystals grown in the Bridgman system unidirectionally with constant growth rate. It is important to understand the mechanisms, which affect lateral segregation such that large radially uniform composition crystal can be produced. Following Coriel, etc's treatment, we have developed a theory to study the effect of a curved melt-solid interface shape on lateral composition distribution. The model is considered to be a cylindrical system with azimuthal symmetry and a curved melt-solid interface shape which can be expressed as a linear combination of a series of Bessell's functions. The results show that melt-solid interface shape has a dominant effect on the lateral composition distribution of these systems. For small values of beta, the solute concentration at the melt-solid interface scales linearly with interface shape with a proportional constant of the produce of beta and (1 -k), where beta = VR/D, with V as growth velocity, R as the sample radius, D as the diffusion constant and k as the distribution constant. A detailed theory will be presented. A computer code has been developed and simulations have been performed and compared with experimental results. These will be published in another paper.
Trapman, Pieter; Bootsma, Martinus Christoffel Jozef
2009-05-01
In this paper we establish a relation between the spread of infectious diseases and the dynamics of so called M/G/1 queues with processor sharing. The relation between the spread of epidemics and branching processes, which is well known in epidemiology, and the relation between M/G/1 queues and birth death processes, which is well known in queueing theory, will be combined to provide a framework in which results from queueing theory can be used in epidemiology and vice versa. In particular, we consider the number of infectious individuals in a standard SIR epidemic model at the moment of the first detection of the epidemic, where infectious individuals are detected at a constant per capita rate. We use a result from the literature on queueing processes to show that this number of infectious individuals is geometrically distributed.
Hättig, Christof; Hellweg, Arnim; Köhn, Andreas
2006-03-14
We present a parallel implementation of second-order Møller-Plesset perturbation theory with the resolution-of-the-identity approximation (RI-MP2). The implementation is based on a recent improved sequential implementation of RI-MP2 within the Turbomole program package and employs the message passing interface (MPI) standard for communication between distributed memory nodes. The parallel implementation extends the applicability of canonical MP2 to considerably larger systems. Examples are presented for full geometry optimizations with up to 60 atoms and 3300 basis functions and MP2 energy calculations with more than 200 atoms and 7000 basis functions.
NASA Astrophysics Data System (ADS)
Ji, Yi-Ming; Li, Yun-Xia; Shi, Lei; Meng, Wen; Cui, Shu-Min; Xu, Zhen-Yu
2015-10-01
Quantum access network can't guarantee the absolute security of multi-user detector and eavesdropper can get access to key information through time-shift attack and other ways. Measurement-device-independent quantum key distribution is immune from all the detection attacks, and accomplishes the safe sharing of quantum key. In this paper, that Measurement-device-independent quantum key distribution is used in the application of multi-user quantum access to the network is on the research. By adopting time-division multiplexing technology to achieve the sharing of multiuser detector, the system structure is simplified and the security of quantum key sharing is acquired.
NASA Technical Reports Server (NTRS)
Drusano, George L.
1991-01-01
The optimal sampling theory is evaluated in applications to studies related to the distribution and elimination of several drugs (including ceftazidime, piperacillin, and ciprofloxacin), using the SAMPLE module of the ADAPT II package of programs developed by D'Argenio and Schumitzky (1979, 1988) and comparing the pharmacokinetic parameter values with results obtained by traditional ten-sample design. The impact of the use of optimal sampling was demonstrated in conjunction with NONMEM (Sheiner et al., 1977) approach, in which the population is taken as the unit of analysis, allowing even fragmentary patient data sets to contribute to population parameter estimates. It is shown that this technique is applicable in both the single-dose and the multiple-dose environments. The ability to study real patients made it possible to show that there was a bimodal distribution in ciprofloxacin nonrenal clearance.
NASA Astrophysics Data System (ADS)
Kim, M.; Pangle, L. A.; Cardoso, C.; Lora, M.; Wang, Y.; Harman, C. J.; Troch, P. A. A.
2014-12-01
Transit time distributions (TTD) are an efficient way of characterizing transport through the complex flow dynamics of a hydrologic system, and can serve as a basis for spatially-integrated solute transport modeling. Recently there has been progress in the development of a theory of time-variable TTDs that captures the effect of temporal variability in the timing of fluxes as well as changes in flow pathways. Furthermore, a new formulation of this theory allows the essential transport properties of a system to be parameterized by a physically meaningful time-variable probability distribution, the Ω function. This distribution determines how the age distribution of water in storage is sampled by the outflow. The form of the Ω function varies if the flow pathways change, but is not determined by the timing of fluxes (unlike the TTD). In this study, we use this theory to characterize transport by transient flows through a homogeneously packed 1 m3 sloping soil lysimeter. The transit time distribution associated with each of four irrigation periods (repeated daily for 24 days) are compared to examine the significance of changes in the Ω function due to variations in total storage, antecedent conditions, and precipitation intensity. We observe both the time-variable TTD and the Ω function experimentally by applying the PERTH method (Harman and Kim, 2014, GRL, 41, 1567-1575). The method allows us to observe multiple overlapping time-variable TTD in controlled experiments using only two conservative tracers. We hypothesize that both the TTD and the Ω function will vary in time, even in this small scale, because water will take different flow pathways depending on the initial state of the lysimeter and irrigation intensity. However, based on primarily modeling, we conjecture that major variability in the Ω function will be limited to a period during and immediately after each irrigation. We anticipate the Ω function is almost time-invariant (or scales simply with
NASA Technical Reports Server (NTRS)
Herzog, J.
1974-01-01
A method of calculating stage parameters and flow distribution of axial turbines is described. The governing equations apply to space between the blade rows and are based on the assumption of rotationally symmetrical, compressible, adiabatic flow conditions. Results are presented for stage design and flow analysis calculations. Theoretical results from the calculation system are compared with experimental data from low pressure steam turbine tests.
ERIC Educational Resources Information Center
Bhattacharyya, Pratip; Chakrabarti, Bikas K.
2008-01-01
We study different ways of determining the mean distance (r[subscript n]) between a reference point and its nth neighbour among random points distributed with uniform density in a D-dimensional Euclidean space. First, we present a heuristic method; though this method provides only a crude mathematical result, it shows a simple way of estimating…
ERIC Educational Resources Information Center
Ferrando, Pere J.; Lorenzo-Seva, Urbano
2001-01-01
Describes a Windows program for checking the suitability of unidimensional logistic item response models for binary and ordered polytomous responses with respect to a given set of data. The program is based on predicting the observed test score distributions from the item characteristic curves. (SLD)
Sampson, Rebecca K; Bellm, Susan M; McCaffery, Anthony J; Lawrance, Warren D
2005-02-15
The translational energy release distribution for dissociation of benzene-Ar has been measured and, in combination with the 6(1)(0) rotational contour of the benzene product observed in emission, used to determine the rotational J,K distribution of 0(0) benzene products formed during dissociation from 6(1). Significant angular momentum is transferred to benzene on dissociation. The 0(0) rotational distribution peaks at J=31 and is skewed to low K:Javerage=27, (K)average=10.3. The average angle between the total angular momentum vector and the unique rotational axis is determined to be 68 degrees. This indicates that benzene is formed tumbling about in-plane axes rather than in a frisbeelike motion, consistent with Ar "pushing off" benzene from an off-center position above or below the plane. The J distribution is very well reproduced by angular momentum model calculations based on an equivalent rotor approach [A. J. McCaffery, M. A. Osborne, R. J. Marsh, W. D. Lawrance, and E. R. Waclawik, J. Chem. Phys. 121, 1694 (2004)], indicating that angular momentum constraints control the partitioning of energy between translation and rotation. Calculations for p-difluorobenzene-Ar suggest that the equivalent rotor model can provide a reasonable prediction of both J and K distributions in prolate (or near prolate) tops when dissociation leads to excitation about the unique, in-plane axis. Calculations for s-tetrazine-Ar require a small maximum impact parameter to reproduce the comparatively low J values seen for the s-tetrazine product. The three sets of calculations show that the maximum impact parameter is not necessarily equal to the bond length of the equivalent rotor and must be treated as a variable parameter. The success of the equivalent rotor calculations argues that angular momentum constraints control the partitioning between rotation and translation of the products.
NASA Astrophysics Data System (ADS)
McCarthy, S.
2014-02-01
This paper describes the theory and application of a perceptually-inspired video processing technology that was recently incorporated into professional video encoders now being used by major cable, IPTV, satellite, and internet video service providers. We will present data that show that this perceptual video processing (PVP) technology can improve video compression efficiency by up to 50% for MPEG-2, H.264, and High Efficiency Video Coding (HEVC). The PVP technology described in this paper works by forming predicted eye-tracking attractor maps that indicate how likely it might be that a free viewing person would look at particular area of an image or video. We will introduce in this paper the novel model and supporting theory used to calculate the eye-tracking attractor maps. We will show how the underlying perceptual model was inspired by electrophysiological studies of the vertebrate retina, and will explain how the model incorporates statistical expectations about natural scenes as well as a novel method for predicting error in signal estimation tasks. Finally, we will describe how the eye-tracking attractor maps are created in real time and used to modify video prior to encoding so that it is more compressible but not noticeably different than the original unmodified video.
Adachi, Satoshi Toda, Mikito Kubotani, Hiroto
2009-11-15
The fixed-trace ensemble of random complex matrices is the fundamental model that excellently describes the entanglement in the quantum states realized in a coupled system by its strongly chaotic dynamical evolution [see H. Kubotani, S. Adachi, M. Toda, Phys. Rev. Lett. 100 (2008) 240501]. The fixed-trace ensemble fully takes into account the conservation of probability for quantum states. The present paper derives for the first time the exact analytical formula of the one-body distribution function of singular values of random complex matrices in the fixed-trace ensemble. The distribution function of singular values (i.e. Schmidt eigenvalues) of a quantum state is so important since it describes characteristics of the entanglement in the state. The derivation of the exact analytical formula utilizes two recent achievements in mathematics, which appeared in 1990s. The first is the Kaneko theory that extends the famous Selberg integral by inserting a hypergeometric type weight factor into the integrand to obtain an analytical formula for the extended integral. The second is the Petkovsek-Wilf-Zeilberger theory that calculates definite hypergeometric sums in a closed form.
NASA Technical Reports Server (NTRS)
Theodorsen, Theodore
1944-01-01
Simple and exact expressions are given for the efficiency of single and dual rotating propellers with ideal circulation distribution as given by the Goldstein functions for single-rotating propellers and by the new functions for dual-rotating propellers from part I of the present series. The efficiency is shown to depend primarily on a defined load factor and, to a very small extent, on an axial loss factor. Tables and charts are included for practical use of the results.
NASA Astrophysics Data System (ADS)
Narsimhan, Vivek; Zhao, Hong; Shaqfeh, Eric S. G.
2013-06-01
We develop a coarse-grained theory to predict the concentration distribution of a suspension of vesicles or red blood cells in a wall-bound Couette flow. This model balances the wall-induced hydrodynamic lift on deformable particles with the flux due to binary collisions, which we represent via a second-order kinetic master equation. Our theory predicts a depletion of particles near the channel wall (i.e., the Fahraeus-Lindqvist effect), followed by a near-wall formation of particle layers. We quantify the effect of channel height, viscosity ratio, and shear-rate on the cell-free layer thickness (i.e., the Fahraeus-Lindqvist effect). The results agree with in vitro experiments as well as boundary integral simulations of suspension flows. Lastly, we examine a new type of collective particle motion for red blood cells induced by hydrodynamic interactions near the wall. These "swapping trajectories," coined by Zurita-Gotor et al. [J. Fluid Mech. 592, 447-469 (2007), 10.1017/S0022112007008701], could explain the origin of particle layering near the wall. The theory we describe represents a significant improvement in terms of time savings and predictive power over current large-scale numerical simulations of suspension flows.
NASA Astrophysics Data System (ADS)
Yang, Delian; Zong, Jing; Wang, Qiang
2012-02-01
Based on the same model system of symmetric diblock copolymers as discrete Gaussian chains with soft, finite-range repulsions as commonly used in dissipative-particle dynamics simulations, we directly compare, without any parameter-fitting, the thermodynamic and structural properties of the disordered phase obtained from fast off-lattice Monte Carlo (FOMC) simulations^1, reference interaction site model (RISM) and polymer reference interaction site model (PRISM) theories, and Gaussian fluctuation theory. The disordered phase ranges from homopolymer melts (i.e., where the Flory-Huggins parameter χ=0) all the way to the order-disorder transition point determined in FOMC simulations, and the compared quantities include the internal energy, entropy, Helmholtz free energy, excess pressure, constant-volume heat capacity, chain/block dimensions, and various structure factors and correlation functions in the system. Our comparisons unambiguously and quantitatively reveal the consequences of various theoretical approximations and the validity of these theories in describing the fluctuations/correlations in disordered diblock copolymers. [1] Q. Wang and Y. Yin, J. Chem. Phys., 130, 104903 (2009).
Maggiano, Corey M; Maggiano, Isabel S; Tiesler, Vera G; Chi-Keb, Julio R; Stout, Sam D
2016-01-01
This study compares two novel methods quantifying bone shaft tissue distributions, and relates observations on human humeral growth patterns for applications in anthropological and anatomical research. Microstructural variation in compact bone occurs due to developmental and mechanically adaptive circumstances that are 'recorded' by forming bone and are important for interpretations of growth, health, physical activity, adaptation, and identity in the past and present. Those interpretations hinge on a detailed understanding of the modeling process by which bones achieve their diametric shape, diaphyseal curvature, and general position relative to other elements. Bone modeling is a complex aspect of growth, potentially causing the shaft to drift transversely through formation and resorption on opposing cortices. Unfortunately, the specifics of modeling drift are largely unknown for most skeletal elements. Moreover, bone modeling has seen little quantitative methodological development compared with secondary bone processes, such as intracortical remodeling. The techniques proposed here, starburst point-count and 45° cross-polarization hand-drawn histomorphometry, permit the statistical and populational analysis of human primary tissue distributions and provide similar results despite being suitable for different applications. This analysis of a pooled archaeological and modern skeletal sample confirms the importance of extreme asymmetry in bone modeling as a major determinant of microstructural variation in diaphyses. Specifically, humeral drift is posteromedial in the human humerus, accompanied by a significant rotational trend. In general, results encourage the usage of endocortical primary bone distributions as an indicator and summary of bone modeling drift, enabling quantitative analysis by direction and proportion in other elements and populations.
Khvorostyanov, V.I.; Curry, J.A.
1999-12-01
The kinetic equation of stochastic condensation derived in Part 1 is solved analytically under some simplifications. Analytical solutions of the gamma-distribution type are found using an analogy and methodology from quantum mechanics. In particular, formulas are derived for the index of the gamma distribution p and the relative dispersion of the droplet size spectra, which determines the rate of precipitation formation and cloud optical properties. An important feature of these solutions is that, although the equation for p includes many parameters that vary by several orders of magnitude, the expression for p leads to a dimensionless quantity of the order 1--10 for a wide variety of cloud types, and the relative dispersion {sigma}, is related directly to the meteorological factors (vertical velocity, turbulence coefficient, dry and moist adiabatic temperature lapse rates) and the properties of the cloud (droplet concentration and mean radius). The following observed behavior of the cloud size spectra is explained quantitatively by the analytical solutions: narrowing of drop size spectra with increased cooling rate, and broadening of drop size spectra with increasing turbulence. The application of these solutions is illustrated using an example of a typical stratus cloud and possible applications for the convective clouds are discussed. The predictions of this solution are compared with some other models and with observations in stratus and convective clouds. These analytical solutions can serve as a basis for the parameterization of the cloud microphysical and optical properties for use in cloud models and general circulation models.
Beauchamp, G
2000-11-07
In population games, the optimal behaviour of a forager depends partly on courses of action selected by other individuals in the population. How individuals learn to allocate effort in foraging games involving frequency-dependent payoffs has been little examined. The performance of three different learning rules was investigated in several types of habitats in each of two population games. Learning rules allow individuals to weigh information about the past and the present and to choose among alternative patterns of behaviour. In the producer-scrounger game, foragers use producer to locate food patches and scrounger to exploit the food discoveries of others. In the ideal free distribution game, foragers that experience feeding interference from companions distribute themselves among heterogeneous food patches. In simulations of each population game, the use of different learning rules induced large variation in foraging behaviour, thus providing a tool to assess the relevance of each learning rule in experimental systems. Rare mutants using alternative learning rules often successfully invaded populations of foragers using other rules indicating that some learning rules are not stable when pitted against each other. Learning rules often closely approximated optimal behaviour in each population game suggesting that stimulus-response learning of contingencies created by foraging companions could be sufficient to perform at near-optimal level in two population games.
Russo, Lucia; Russo, Paola; Siettos, Constantinos I
2016-01-01
Based on complex network theory, we propose a computational methodology which addresses the spatial distribution of fuel breaks for the inhibition of the spread of wildland fires on heterogeneous landscapes. This is a two-level approach where the dynamics of fire spread are modeled as a random Markov field process on a directed network whose edge weights are determined by a Cellular Automata model that integrates detailed GIS, landscape and meteorological data. Within this framework, the spatial distribution of fuel breaks is reduced to the problem of finding network nodes (small land patches) which favour fire propagation. Here, this is accomplished by exploiting network centrality statistics. We illustrate the proposed approach through (a) an artificial forest of randomly distributed density of vegetation, and (b) a real-world case concerning the island of Rhodes in Greece whose major part of its forest was burned in 2008. Simulation results show that the proposed methodology outperforms the benchmark/conventional policy of fuel reduction as this can be realized by selective harvesting and/or prescribed burning based on the density and flammability of vegetation. Interestingly, our approach reveals that patches with sparse density of vegetation may act as hubs for the spread of the fire.
Russo, Lucia; Russo, Paola; Siettos, Constantinos I.
2016-01-01
Based on complex network theory, we propose a computational methodology which addresses the spatial distribution of fuel breaks for the inhibition of the spread of wildland fires on heterogeneous landscapes. This is a two-level approach where the dynamics of fire spread are modeled as a random Markov field process on a directed network whose edge weights are determined by a Cellular Automata model that integrates detailed GIS, landscape and meteorological data. Within this framework, the spatial distribution of fuel breaks is reduced to the problem of finding network nodes (small land patches) which favour fire propagation. Here, this is accomplished by exploiting network centrality statistics. We illustrate the proposed approach through (a) an artificial forest of randomly distributed density of vegetation, and (b) a real-world case concerning the island of Rhodes in Greece whose major part of its forest was burned in 2008. Simulation results show that the proposed methodology outperforms the benchmark/conventional policy of fuel reduction as this can be realized by selective harvesting and/or prescribed burning based on the density and flammability of vegetation. Interestingly, our approach reveals that patches with sparse density of vegetation may act as hubs for the spread of the fire. PMID:27780249
NASA Astrophysics Data System (ADS)
Splinter, Robert; Littmann, Laszlo; Tuntelder, Jan R.; Svenson, Robert H.; Chuang, Chi Hui; Tatsis, George P.; Semenov, Serguei Y.; Nanney, Glenn A.
1995-01-01
Tissue samples ranging from 2 to 16 mm in thickness were irradiated at 1064 nm with energies ranging from 40 to 2400 J. Coagulation lesions of in vitro and in vivo experiments were subjected to temperature profiling and submitted for histology. Irreversible damage was calculated with the damage integral formalism, following the bioheat equation solved with Monte Carlo computer light-distribution simula-tions. Numerical temperature rise and coagulation depth compared well with the in vitro results. The in vivo data required a change in the optical properties based on integrating sphere measurements for high irradiance to make the experimental and numerical data converge. The computer model has successfully solved several light-tissue interaction situations in which scattering dominates over absorption.
Huertas, M L; Cruz, V; Cascales, J J; Acuña, A U; García de la Torre, J
1996-01-01
We propose a simple model for the distribution of position and orientation and the diffusion of a hydrophobic probe molecule embedded in a membrane. The molecule experiences both a Maier-Saupe orienting potential as well as an enclosing potential of repulsion from the membrane walls. A statistical thermodynamics treatment of the model provides predictions of the location and orientation of the molecule within the membrane. In particular, we evaluate the order parameter of the molecule in terms of the model constants. The diffusivity of the probe is studied by Brownian dynamics simulation. For rotational diffusion, we check an available analytical approximate treatment that allows for the prediction of the dynamics in terms of equilibrium quantities. We also pay attention to quantities related to the initial and mean reorientational rate of the probe. For translational diffusion, we use the simulation results to analyze some general aspects of lateral and transversal diffusion. Images FIGURE 3 FIGURE 6 FIGURE 7 PMID:8874017
Nigg, D W; Randolph, P D; Wheeler, F J
1991-01-01
The Monte Carlo stochastic simulation technique has traditionally been the only well-recognized method for computing three-dimensional radiation dose distributions in connection with boron neutron capture therapy (BNCT) research. A deterministic approach to this problem would offer some advantages over the Monte Carlo method. This paper describes an application of a deterministic method to analytically simulate BNCT treatment of a canine head phantom using the epithermal neutron beam at the Brookhaven medical research reactor (BMRR). Calculations were performed with the TORT code from Oak Ridge National Laboratory (ORNL), an implementation of the discrete ordinates, or Sn method. Calculations were from first principles and used no empirical correction factors. The phantom surface was modeled by flat facets of approximately 1 cm2. The phantom interior was homogeneous. Energy-dependent neutron and photon scalar fluxes were calculated on a 32 x 16 x 22 mesh structure with 96 discrete directions in angular phase space. The calculation took 670 min on an Apollo DN10000 workstation. The results were subsequently integrated over energy to obtain full three-dimensional dose distributions. Isodose contours and depth-dose curves were plotted for several separate dose components of interest. Phantom measurements were made by measuring neutron activation (and therefore neutron flux) as a function of depth in copper-gold alloy wires that were inserted through catheters placed in holes drilled in the phantom. Measurements agreed with calculations to within about 15%. The calculations took about an order of magnitude longer than comparable Monte Carlo calculations but provided various conveniences, as well as a useful check.
2009-01-01
The past decade witnessed great progress in research on health inequities. The most widely cited definition of health inequity is, arguably, the one proposed by Whitehead and Dahlgren: "Health inequalities that are avoidable, unnecessary, and unfair are unjust." We argue that this definition is useful but in need of further clarification because it is not linked to broader theories of justice. We propose an alternative, pluralist notion of fair distribution of health that is compatible with several theories of distributive justice. Our proposed view consists of the weak principle of health equality and the principle of fair trade-offs. The weak principle of health equality offers an alternative definition of health equity to those proposed in the past. It maintains the all-encompassing nature of the popular Whitehead/Dahlgren definition of health equity, and at the same time offers a richer philosophical foundation. This principle states that every person or group should have equal health except when: (a) health equality is only possible by making someone less healthy, or (b) there are technological limitations on further health improvement. In short, health inequalities that are amenable to positive human intervention are unfair. The principle of fair trade-offs states that weak equality of health is morally objectionable if and only if: (c) further reduction of weak inequality leads to unacceptable sacrifices of average or overall health of the population, or (d) further reduction in weak health inequality would result in unacceptable sacrifices of other important goods, such as education, employment, and social security. PMID:19922612
Rooman, Marianne; Wintjens, René
2013-01-01
DNA is subject to oxidative damage due to radiation or by-products of cellular metabolism, thereby creating electron holes that migrate along the DNA stacks. A systematic computational analysis of the dependence of the electronic properties of nucleobase stacks on sequence and conformation was performed here, on the basis of single- and double-stranded homo-nucleobase stacks of 1–10 bases or 1–8 base pairs in standard A-, B-, and Z-conformation. First, several levels of theory were tested for calculating the vertical ionization potentials of individual nucleobases; the M06-2X/6-31G* hybrid density functional theory method was selected by comparison with experimental data. Next, the vertical ionization potential, and the Mulliken charge and spin density distributions were calculated and considered on all nucleobase stacks. We found that (1) the ionization potential decreases with the number of bases, the lowest being reached by Gua≡Cyt tracts; (2) the association of two single strands into a double-stranded tract lowers the ionization potential significantly (3) differences in ionization potential due to sequence variation are roughly three times larger than those due to conformational modifications. The charge and spin density distributions were found (1) to be located toward the 5′-end for single-stranded Gua-stacks and toward the 3′-end for Cyt-stacks and basically delocalized over all bases for Ade- and Thy-stacks; (2) the association into double-stranded tracts empties the Cyt- and Thy-strands of most of the charge and all the spin density and concentrates them on the Gua- and Ade-strands. The possible biological implications of these results for transcription are discussed. PMID:23582046
Benjamin A. Frandsen; Brunelli, Michela; Page, Katharine; Uemura, Yasutomo J.; Staunton, Julie B.; Billinge, Simon J. L.
2016-05-11
Here, we present a temperature-dependent atomic and magnetic pair distribution function (PDF) analysis of neutron total scattering measurements of antiferromagnetic MnO, an archetypal strongly correlated transition-metal oxide. The known antiferromagnetic ground-state structure fits the low-temperature data closely with refined parameters that agree with conventional techniques, confirming the reliability of the newly developed magnetic PDF method. The measurements performed in the paramagnetic phase reveal significant short-range magnetic correlations on a ~1 nm length scale that differ substantially from the low-temperature long-range spin arrangement. Ab initio calculations using a self-interaction-corrected local spin density approximation of density functional theory predict magnetic interactions dominated by Anderson superexchange and reproduce the measured short-range magnetic correlations to a high degree of accuracy. Further calculations simulating an additional contribution from a direct exchange interaction show much worse agreement with the data. Furthermore, the Anderson superexchange model for MnO is thus verified by experimentation and confirmed by ab initio theory.
Clark, G
2003-04-28
This report describes a feasibility study. We are interested in calculating the angular and linear velocities of a re-entry vehicle using six acceleration signals from a distributed accelerometer inertial measurement unit (DAIMU). Earlier work showed that angular and linear velocity calculation using classic nonlinear ordinary differential equation (ODE) solvers is not practically feasible, due to mathematical and numerical difficulties. This report demonstrates the theoretical feasibility of using model-based nonlinear state estimation techniques to obtain the angular and linear velocities in this problem. Practical numerical and calibration issues require additional work to resolve. We show that the six accelerometers in the DAIMU are not sufficient to provide observability, so additional measurements of the system states are required (e.g. from a Global Positioning System (GPS) unit). Given the constraint that our system cannot use GPS, we propose using the existing on-board 3-axis magnetometer to measure angular velocity. We further show that the six nonlinear ODE's for the vehicle kinematics can be decoupled into three ODE's in the angular velocity and three ODE's in the linear velocity. This allows us to formulate a three-state Gauss-Markov system model for the angular velocities, using the magnetometer signals in the measurement model. This re-formulated model is observable, allowing us to build an Extended Kalman Filter (EKF) for estimating the angular velocities. Given the angular velocity estimates from the EKF, the three ODE's for the linear velocity become algebraic, and the linear velocity can be calculated by numerical integration. Thus, we do not need direct measurements of the linear velocity to provide observability, and the technique is mathematically feasible. Using a simulation example, we show that the estimator adds value over the numerical ODE solver in the presence of measurement noise. Calculating the velocities in the presence of
Hong QIn, Ronald Davidson
2011-07-18
The Courant-Snyder (CS) theory and the Kapchinskij-Vladimirskij (KV) distribution for high-intensity beams in a uncoupled focusing lattice are generalized to the case of coupled transverse dynamics. The envelope function is generalized to an envelope matrix, and the envelope equation becomes a matrix envelope equation with matrix operations that are non-commutative. In an uncoupled lattice, the KV distribution function, first analyzed in 1959, is the only known exact solution of the nonlinear Vlasov-Maxwell equations for high-intensity beams including self-fields in a self-consistent manner. The KV solution is generalized to high-intensity beams in a coupled transverse lattice using the generalized CS invariant. This solution projects to a rotating, pulsating elliptical beam in transverse configuration space. The fully self-consistent solution reduces the nonlinear Vlasov-Maxwell equations to a nonlinear matrix ordinary differential equation for the envelope matrix, which determines the geometry of the pulsating and rotating beam ellipse. These results provide us with a new theoretical tool to investigate the dynamics of high-intensity beams in a coupled transverse lattice. A strongly coupled lattice, a so-called N-rolling lattice, is studied as an example. It is found that strong coupling does not deteriorate the beam quality. Instead, the coupling induces beam rotation, and reduces beam pulsation.
Qin Hong; Davidson, Ronald C.
2011-05-15
The Courant-Snyder (CS) theory and the Kapchinskij-Vladimirskij (KV) distribution for high-intensity beams in an uncoupled focusing lattice are generalized to the case of coupled transverse dynamics. The envelope function is generalized to an envelope matrix, and the envelope equation becomes a matrix envelope equation with matrix operations that are noncommutative. In an uncoupled lattice, the KV distribution function, first analyzed in 1959, is the only known exact solution of the nonlinear Vlasov-Maxwell equations for high-intensity beams including self-fields in a self-consistent manner. The KV solution is generalized to high-intensity beams in a coupled transverse lattice using the generalized CS invariant. This solution projects to a rotating, pulsating elliptical beam in transverse configuration space. The fully self-consistent solution reduces the nonlinear Vlasov-Maxwell equations to a nonlinear matrix ordinary differential equation for the envelope matrix, which determines the geometry of the pulsating and rotating beam ellipse. These results provide us with a new theoretical tool to investigate the dynamics of high-intensity beams in a coupled transverse lattice. A strongly coupled lattice, a so-called N-rolling lattice, is studied as an example. It is found that strong coupling does not deteriorate the beam quality. Instead, the coupling induces beam rotation and reduces beam pulsation.
NASA Astrophysics Data System (ADS)
Y Ling, Daniel; Ling, Xinsheng Sean
2013-09-01
In this short paper, a correction is made to the recently proposed solution of Li and Talaga to a 1D biased diffusion model for linear DNA translocation, and a new analysis will be given to their data. It was pointed out by us recently that this 1D linear translocation model is equivalent to the one that was considered by Schrödinger for the Ehrenhaft-Millikan measurements on electron charge. Here, we apply Schrödinger’s first-passage-time distribution formula to the data set in Li and Talaga. It is found that Schrödinger’s formula can be used to describe the time distribution of DNA translocation in solid-state nanopores. These fittings yield two useful parameters: the drift velocity of DNA translocation and the diffusion constant of DNA inside the nanopore. The results suggest two regimes of DNA translocation: (I) at low voltages, there are clear deviations from Smoluchowski’s linear law of electrophoresis, which we attribute to the entropic barrier effects; (II) at high voltages, the translocation velocity is a linear function of the applied electric field. In regime II, the apparent diffusion constant exhibits a quadratic dependence on the applied electric field, suggesting a mechanism of Taylor-dispersion effect likely due the electro-osmotic flow field in the nanopore channel. This analysis yields a dispersion-free diffusion constant value of 11.2 nm2 μs-1 for the segment of DNA inside the nanopore, which is in quantitative agreement with the Stokes-Einstein theory. The implication of Schrödinger’s formula for DNA sequencing is discussed.
NASA Astrophysics Data System (ADS)
Cattabiani, Alessandro; Barbarulo, Andrea; Riou, Hervé; Ladevèze, Pierre
2015-12-01
Recently, interest of aerospace and automotive industries on medium-frequency vibrational behavior of composite shell structures has grown due to their high specific stiffness and fatigue resistance. Conventional methods such as the finite element method and the statistical energy analysis are not suitable for the medium-frequency bandwidth. Conversely, the variational theory of complex rays (VTCR) is taking place as an ad-hoc technique to tackle such frequency band. It is a Trefftz method based on a weak variational formulation. Equilibrium equations are met using exact solutions as shape functions. The variational problem imposes boundary conditions in weak form. The present paper extends VTCR to orthotropic shell structures. Moreover, several new enhancements are introduced. Now, we use a quasi-symmetric ray distribution which can greatly reduce computational costs, and addresses in-plane inertia which was neglected in previous works. Some relevant numerical examples are presented to show the strategy and results are compared with a FEM reference to study performances.
NASA Technical Reports Server (NTRS)
Pesetskaya, N. N.; Timofeev, I. YA.; Shipilov, S. D.
1988-01-01
In recent years much attention has been given to the development of methods and programs for the calculation of the aerodynamic characteristics of multiblade, saber-shaped air propellers. Most existing methods are based on the theory of lifting lines. Elsewhere, the theory of a lifting surface is used to calculate screw and lifting propellers. In this work, methods of discrete eddies are described for the calculation of the aerodynamic characteristics of propellers using the linear and nonlinear theories of lifting surfaces.
ERIC Educational Resources Information Center
SAW, J.G.
THIS VOLUME DEALS WITH THE BIVARIATE NORMAL DISTRIBUTION. THE AUTHOR MAKES A DISTINCTION BETWEEN DISTRIBUTION AND DENSITY FROM WHICH HE DEVELOPS THE CONSEQUENCES OF THIS DISTINCTION FOR HYPOTHESIS TESTING. OTHER ENTRIES IN THIS SERIES ARE ED 003 044 AND ED 003 045. (JK)
Silveira, Rodrigo L; Stoyanov, Stanislav R; Gusarov, Sergey; Skaf, Munir S; Kovalenko, Andriy
2015-01-02
Plant biomass recalcitrance, a major obstacle to achieving sustainable production of second generation biofuels, arises mainly from the amorphous cell-wall matrix containing lignin and hemicellulose assembled into a complex supramolecular network that coats the cellulose fibrils. We employed the statistical-mechanical, 3D reference interaction site model with the Kovalenko-Hirata closure approximation (or 3D-RISM-KH molecular theory of solvation) to reveal the supramolecular interactions in this network and provide molecular-level insight into the effective lignin-lignin and lignin-hemicellulose thermodynamic interactions. We found that such interactions are hydrophobic and entropy-driven, and arise from the expelling of water from the mutual interaction surfaces. The molecular origin of these interactions is carbohydrate-π and π-π stacking forces, whose strengths are dependent on the lignin chemical composition. Methoxy substituents in the phenyl groups of lignin promote substantial entropic stabilization of the ligno-hemicellulosic matrix. Our results provide a detailed molecular view of the fundamental interactions within the secondary plant cell walls that lead to recalcitrance.
Regnier, D.; Dubray, N.; Schunck, N.; Verriere, M.
2016-05-13
Here, accurate knowledge of fission fragment yields is an essential ingredient of numerous applications ranging from the formation of elements in the r process to fuel cycle optimization for nuclear energy. The need for a predictive theory applicable where no data are available, together with the variety of potential applications, is an incentive to develop a fully microscopic approach to fission dynamics.
Romero, V.J.
1994-03-01
CIRCE2 is a computer code for modeling the optical performance of three-dimensional dish-type solar energy concentrators. Statistical methods are used to evaluate the directional distribution of reflected rays from any given point on the concentrator. Given concentrator and receiver geometries, sunshape (angular distribution of incident rays from the sun), and concentrator imperfections such as surface roughness and random deviation in slope, the code predicts the flux distribution and total power incident upon the target. Great freedom exists in the variety of concentrator and receiver configurations that can be modeled. Additionally, provisions for shading and receiver aperturing are included.- DEKGEN2 is a preprocessor designed to facilitate input of geometry, error distributions, and sun models. This manual describes the optical model, user inputs, code outputs, and operation of the software package. A user tutorial is included in which several collectors are built and analyzed in step-by-step examples.
Czakó, Gábor
2014-06-21
Motivated by a recent experiment [H. Pan and K. Liu, J. Chem. Phys. 140, 191101 (2014)], we report a quasiclassical trajectory study of the O((3)P) + CH4(vk = 0, 1) → OH + CH3 [k = 1 and 3] reactions on an ab initio potential energy surface. The computed angular distributions and cross sections correlated to the OH(v = 0, 1) + CH3(v = 0) coincident product states can be directly compared to experiment for O + CH4(v3 = 0, 1). Both theory and experiment show that the ground-state reaction is backward scattered, whereas the angular distributions shift toward sideways and forward directions upon antisymmetric stretching (v3) excitation of the reactant. Theory predicts similar behavior for the O + CH4(v1 = 1) reaction. The simulations show that stretching excitation enhances the reaction up to about 15 kcal/mol collision energy, whereas the O + CH4(vk = 1) reactions produce smaller cross sections for OH(v = 1) + CH3(v = 0) than those of O + CH4(v = 0) → OH(v = 0) + CH3(v = 0). The former finding agrees with experiment and the latter awaits for confirmation. The computed cold OH rotational distributions of O + CH4(v = 0) are in good agreement with experiment.
NASA Technical Reports Server (NTRS)
Singh, J. J.; Smith, A. S.; Chan, L. Y.; Yue, G. K.
1982-01-01
Thomson's ion nucleation theory was modified to include the effects of curvature dependence of the microscopic surface tension of field dependent, nonlinear, dielectric properties of the liquid; and of sulfuric acid hydrate formation in binary mixtures of water and sulfuric acid vapors. The modified theory leads to a broadening of the ion cluster spectrum, and shifts it towards larger numbers of H2O and H2SO4 molecules. Whether there is more shifting towards larger numbers of H2O or H2SO4 molecules depends on the relative humidity and relative acidity of the mixture. Usually, a broadening of the spectrum is accompanied by a lowering of the mean cluster intensity. For fixed values of relative humidity and relative acidity, a similar broadening pattern is observed when the temperature is lowered. These features of the modified theory illustrate that a trace of sulfuric acid can facilitate the formation of ultrafine, stable, prenucleation ion clusters as well as the growth of the prenucleation ion clusters towards the critical saddle point conditions, even with low values of relative humidity and relative acidity.
Sun, Z; Ying, H
1999-02-01
Non-invasive determination of temperature distribution in biological media is important in many heating-related studies, such as thermal treatment. In this paper, we present an in vitro ultrasound technique for estimation of temperature distribution in heated tissue. Our technique consists of two major steps: (1) using multiple time gates to track echo signals scattered from tissue regions at different depths; (2) estimating temperature distribution based on heating-induced changes of arrival times of echo signals scattered from the targeted tissue regions. We use the conventional cross-correlation approach to track echoes. For temperature estimation, we have developed an iterative method that takes into account the influences of thermal expansion and heating-induced change in the speed of sound on the time of flight. We have introduced a concept of thermal sensitivity of the time of flight and used it to derive a theoretical formula that relates the achievable accuracy on the estimation of tissue temperature to seven parameters. The seven parameters are tissue thermal sensitivity of the time of flight, signal-to-noise ratio, bandwidth and center frequency of the signal, degree of signal decorrelation induced by changes in tissue physical properties during tissue heating, and widths and spacing of the time gates. We tested our technique by computer simulation, using a random discrete scatterer model and temperature distribution data acquired in our laser heating experiments on prostate tissue of live dog. Simulation results showed that our technique could accurately estimate the temperature distribution in the heated tissue. Our technique is fast in terms of computation and could be used as a research tool for in vitro real-time monitoring of temperature distribution in tissue under hyperthermal heating.
Wang, Xin; Li, Zhaosheng; Zou, Zhigang
2015-07-15
Although the crystallographic space group has been determined, detailed first principles calculations of the LaTiO2N semiconductor photocatalyst crystal have not been performed because of the nitrogen/oxygen sosoloid-like anion distribution. In this study, based on the Heyd-Scuseria-Ernzerhof method and experimental anion content, we present the possibility of determining detailed information about the LaTiO2N sosoloid-like anion distribution by dividing the anions into possible primitive cells. The detailed information about the anion distribution based on the characteristics of the energetically acceptable primitive cell structures suggests that the LaTiO2N structure is composed of aperiodic stacks of six building-block primitive cells, the non-vacancy primitive cells are located at the surface as effective photoreaction sites, and vacancy structures are located in the bulk. The surface oxide-rich structures increase the near-surface conduction band minimum rise and strengthen photoelectron transport to the bulk, while the content of the bulk vacancy structures should be balanced because of being out of photoreactions. This study is expected to provide a different perspective to understanding the LaTiO2N sosoloid-like anion distribution.
Racemic fluids of hard molecules
NASA Astrophysics Data System (ADS)
Vatamanu, J.; Cann, N. M.
2001-05-01
The structure in four racemic fluids is explored using two integral equation theories: the reference interaction site method (RISM) [D. Chandler and H. C. Andersen, J. Chem. Phys. 57, 1930 (1972)] and the diagrammatically correct theory of Chandler, Silbey, and Ladanyi (CSL) [D. Chandler, R. Silbey, and B. M. Ladanyi, Mol. Phys. 46, 1335 (1982)]. Discrimination is measured by comparison of site pair distributions for sites on identical molecules with the corresponding distributions for sites on mirror-image molecules. We find that discrimination is largest for distributions between the smallest sites in the molecules. Between racemates, those consisting of more asymmetrical chiral molecules (i.e., with a bigger range of site sizes and bond lengths) show the largest discrimination. The indirect correlation function is shown to be nondiscriminating in racemates. Further, exact relationships between like-like and like-unlike differences in the other pair functions have been obtained. From these, the importance of the bridge functions in discrimination is evident. The CSL theory always satisfies the exact relationships, even with approximate bridge diagrams. RISM theory cannot satisfy these exact limits regardless of density and closure relation. We have found that RISM theory predicts qualitatively incorrect pair distributions at low densities, but that the difference in the distributions is more accurate. All bridge diagrams which contribute to O(ρo) have been enumerated and evaluated. Inclusion of these diagrams into the CSL theory leads to exact results at low density. However, we find that the inclusion of the ρo diagrams has dramatically improved the quality of the CSL theory at all densities.
NASA Astrophysics Data System (ADS)
Jin, Jae Sik
2017-03-01
Phonon dynamics in nanostructures is critically important to thermoelectric and optoelectronic devices because it determines the transport and other crucial properties. However, accurately evaluating the phonon lifetimes is extremely difficult. This study reports on the development of a new semi-empirical method to estimate the full-spectrum phonon lifetimes in thin silicon films at room temperature based on the experimental data on the phonon mean-free-path spectrum in bulk silicon and a phenomenological consideration of phonon transport in thin films. The bulk of this work describes the theory and the validation; then, we discuss the trend of the phonon lifetimes in thin silicon films when their thicknesses decrease.
NASA Technical Reports Server (NTRS)
Chutjian, A.; Msezane, A. Z.; Henry, R. J. W.
1983-01-01
Differential electron-scattering cross sections for inelastic excitation of an ion have been measured for the first time. Experiments were carried out in a cross electron-ion beam geometry for the 4(2)S yields 4(2)P transition in Zn II at 75 eV. In addition, differential cross sections were calculated at energies between 15 and 100 eV in a five-state close-coupling approximation in which 4s, 4p, 3d(9)4s(2), 5s, and 4 d states were included. Agreement in shape between theory and experiment at 75 eV is excellent.
String Theory and Gauge Theories
Maldacena, Juan
2009-02-20
We will see how gauge theories, in the limit that the number of colors is large, give string theories. We will discuss some examples of particular gauge theories where the corresponding string theory is known precisely, starting with the case of the maximally supersymmetric theory in four dimensions which corresponds to ten dimensional string theory. We will discuss recent developments in this area.
2015-03-26
serviceability – how easy is it to repair the product? (5) aesthetics – what does the product look like? ( 6 ) features – what does the product do? (7...is the definition of value, which is deemed by Kang and Apte (2007) as the heart of the lean thinking . They also define value as “form, feature or...THE BRAZILIAN AIR FORCE UNIFORM DISTRIBUTION PROCESS: USING LEAN THINKING , STATISTICAL PROCESS
NASA Technical Reports Server (NTRS)
Macready, William; Wolpert, David
2005-01-01
We demonstrate a new framework for analyzing and controlling distributed systems, by solving constrained optimization problems with an algorithm based on that framework. The framework is ar. information-theoretic extension of conventional full-rationality game theory to allow bounded rational agents. The associated optimization algorithm is a game in which agents control the variables of the optimization problem. They do this by jointly minimizing a Lagrangian of (the probability distribution of) their joint state. The updating of the Lagrange parameters in that Lagrangian is a form of automated annealing, one that focuses the multi-agent system on the optimal pure strategy. We present computer experiments for the k-sat constraint satisfaction problem and for unconstrained minimization of NK functions.
NASA Astrophysics Data System (ADS)
Harman, Ciaran J.
2015-01-01
Transport processes and pathways through many hydrodynamic systems vary over time, often driven by variations in total water storage. This paper develops a very general approach to modeling unsteady transport through an arbitrary control volume (such as a watershed) that accounts for temporal variability in the underlying transport dynamics. Controls on the selection of discharge from stored water are encapsulated in probability distributions ΩQ>(ST,t>) of age-ranked storage ST (the volume of water in storage ranked from youngest to oldest). This framework is applied to a long-term record of rainfall and streamflow chloride in a small, humid watershed at Plynlimon, UK. While a time-invariant gamma distribution for ΩQ produced a good fit to data, the fit was significantly improved when the distribution was allowed to vary with catchment storage. However, the variation was inverse to that of a "well-mixed" system where storage has a pure dilution effect. Discharge at high storage was predicted to contain a larger fraction of recent event water than at low storage. The effective volume of storage involved in transport was 3411 mm at mean catchment wetness, but declined by 71 mm per 1 mm of additional catchment storage, while the fraction of event water in discharge increased by 1.4%. This "inverse storage effect" is sufficient to reproduce the observed long-memory 1/f fractal spectral structure of stream chloride. Metrics quantifying the strength and direction of storage effects are proposed as useful signatures, and point toward a unified framework for observing and modeling coupled watershed flow and transport.
Fagan, Jeffrey A; Sides, Paul J; Prieve, Dennis C
2004-06-08
Electroosmotic flow in the vicinity of a colloidal particle suspended over an electrode accounts for observed changes in the average height of the particle when the electrode passes alternating current at 100 Hz. The main findings are (1) electroosmotic flow provides sufficient force to move the particle and (2) a phase shift between the purely electrical force on the particle and the particle's motion provides evidence of an E2 force acting on the particle. The electroosmotic force in this case arises from the boundary condition applied when faradaic reactions occur on the electrode. The presence of a potential-dependent electrode reaction moves the likely distribution of electrical current at the electrode surface toward uniform current density around the particle. In the presence of a particle the uniform current density is associated with a nonuniform potential; thus, the electric field around the particle has a nonzero radial component along the electrode surface, which interacts with unbalanced charge in the diffuse double layer on the electrode to create a flow pattern and impose an electroosmotic-flow-based force on the particle. Numerical solutions are presented for these additional height-dependent forces on the particle as a function of the current distribution on the electrode and for the time-dependent probability density of a charged colloidal particle near a planar electrode with a nonuniform electrical potential boundary condition. The electrical potential distribution on the electrode, combined with a phase difference between the electric field in solution and the electrode potential, can account for the experimentally observed motion of particles in ac electric fields in the frequency range from approximately 10 to 200 Hz.
ERIC Educational Resources Information Center
Golledge, Reginald G.
1996-01-01
Discusses the origin of theories in geography and particularly the development of location theories. Considers the influence of economic theory on agricultural land use, industrial location, and geographic location theories. Explores a set of interrelated activities that show how the marketing process illustrates process theory. (MJP)
Roy, G; Bissonnette, L; Bastille, C; Vallée, G
1999-08-20
Multiple-field-of-view (MFOV) secondary-polarization lidar signals are used to calculate the particle-size density distribution (PSD) at the base of a cloud. At the cloud base, multiple scattering is weak and single backscattering is predominant by many orders of magnitude. Because secondary polarization is a direct measure of multiple scattering, it is therefore advantageous to use secondary polarization. A mathematical relation among the PSD, the lidar fields of view, the scattering angles, and the angular depolarization is derived to facilitate use of secondary polarization. The model is supported by experimental MFOV lidar measurements carried out in a controlled environment, and its limitations and restrictions are discussed.
1983-12-16
control of K+ distribution of the smooth muscle in teniae coli of guinea pig were reported by Jones [68]. 42 Ling 40 - S20- 100 r- °P02 so / 60 20 0 .5...p. 252.) Inset, 2 from Relsin and Gulati [65] shows temperature transitions from K + to the Na state in the guinea pig teniae coli. (Prom G. N. Ling...mammalian smooth muscle, the guinea pig teniae coli [65]. If this temperature transition also occurs in uterine smooth muscle-- a reasonable assumption
Kok, Jasper F
2011-01-18
Mineral dust aerosols impact Earth's radiation budget through interactions with clouds, ecosystems, and radiation, which constitutes a substantial uncertainty in understanding past and predicting future climate changes. One of the causes of this large uncertainty is that the size distribution of emitted dust aerosols is poorly understood. The present study shows that regional and global circulation models (GCMs) overestimate the emitted fraction of clay aerosols (< 2 μm diameter) by a factor of ∼2-8 relative to measurements. This discrepancy is resolved by deriving a simple theoretical expression of the emitted dust size distribution that is in excellent agreement with measurements. This expression is based on the physics of the scale-invariant fragmentation of brittle materials, which is shown to be applicable to dust emission. Because clay aerosols produce a strong radiative cooling, the overestimation of the clay fraction causes GCMs to also overestimate the radiative cooling of a given quantity of emitted dust. On local and regional scales, this affects the magnitude and possibly the sign of the dust radiative forcing, with implications for numerical weather forecasting and regional climate predictions in dusty regions. On a global scale, the dust cycle in most GCMs is tuned to match radiative measurements, such that the overestimation of the radiative cooling of a given quantity of emitted dust has likely caused GCMs to underestimate the global dust emission rate. This implies that the deposition flux of dust and its fertilizing effects on ecosystems may be substantially larger than thought.
NASA Astrophysics Data System (ADS)
Pirnat, Miha; Čepon, Gregor; Boltežar, Miha
2014-03-01
In this paper three approaches are combined to develop a structural-acoustic model of a rectangular plate-cavity system with an attached distributed mass and internal sound source. The first approach results from a recently presented analysis based on the Rayleigh-Ritz method and is used to circumvent the difficulties in obtaining the natural frequencies and mode shapes of a plate with an attached, distributed mass. Furthermore, different plate boundary conditions can be accommodated. The resulting mode shapes are defined as continuous functions; this is advantageous as they can be directly used in the second approach, i.e., the classic modal-interaction approach in order to obtain the coupled equations of the system. Finally, in the third approach a group of point sources emitting a pressure pulse in the time domain is used to model an internal sound source. For the validation of the developed model an experiment was conducted in two configurations using a simply supported aluminium plate and a clamped plate coupled with a plexiglas box containing a loudspeaker. Good agreement was found between the analytical and experimental data.
ERIC Educational Resources Information Center
Schubert, Leo
1973-01-01
Briefly describes two antagonistic learning theories: the Association Theory proposed by Skinner and the Field or Cognitive Theory supported by Piaget. Suggests the need for consistency in theoretical approach in the teaching of science at the college level. (JR)
Theory of heterogeneous viscoelasticity
NASA Astrophysics Data System (ADS)
Schirmacher, Walter; Ruocco, Giancarlo; Mazzone, Valerio
2016-03-01
We review a new theory of viscoelasticity of a glass-forming viscous liquid near and below the glass transition. In our model, we assume that each point in the material has a specific viscosity, which varies randomly in space according to a fluctuating activation free energy. We include a Maxwellian elastic term, and assume that the corresponding shear modulus fluctuates as well with the same distribution as that of the activation barriers. The model is solved in coherent potential approximation, for which a derivation is given. The theory predicts an Arrhenius-type temperature dependence of the viscosity in the vanishing frequency limit, independent of the distribution of the activation barriers. The theory implies that this activation energy is generally different from that of a diffusing particle with the same barrier height distribution. If the distribution of activation barriers is assumed to have the Gaussian form, the finite-frequency version of the theory describes well the typical low-temperature alpha relaxation peak of glasses. Beta relaxation can be included by adding another Gaussian with centre at much lower energies than that is responsible for the alpha relaxation. At high frequencies, our theory reduces to the description of an elastic medium with spatially fluctuating elastic moduli (heterogeneous elasticity theory), which explains the occurrence of the boson peak-related vibrational anomalies of glasses.
NASA Astrophysics Data System (ADS)
Plewa, Tomasz; Handy, Timothy; Odrzywolek, Andrzej
2014-03-01
We compute and discuss the process of nucleosynthesis in a series of core-collapse explosion models of a 15 solar mass, blue supergiant progenitor. We obtain nucleosynthetic yields and study the evolution of the chemical element distribution from the moment of core bounce until young supernova remnant phase. Our models show how the process of energy deposition due to radioactive decay modifies the dynamics and the core ejecta structure on small and intermediate scales. The results are compared against observations of young supernova remnants including Cas A and the recent data obtained for SN 1987A. The work has been supported by the NSF grant AST-1109113 and DOE grant DE-FG52-09NA29548. This research used resources of the National Energy Research Scientific Computing Center, which is supported by the U.S. DoE under Contract No. DE-AC02-05CH11231.
NASA Astrophysics Data System (ADS)
Tkáč, Štefan
2015-11-01
To achieve the smart growth and equitable development in the region, urban planners should consider also lateral energies represented by the energy urban models like further proposed EEPGC focused on energy distribution via connections among micro-urban structures, their onsite renewable resources and the perception of micro-urban structures as decentralized energy carriers based on pre industrialized era. These structures are still variously bound when part of greater patterns. After the industrial revolution the main traded goods became energy in its various forms. The EEPGC is focused on sustainable energy transportation distances between the villages and the city, described by the virtual "energy circles". This more human scale urbanization, boost the economy in micro-urban areas, rising along with clean energy available in situ that surely gives a different perspective to human quality of life in contrast to overcrowded multicultural mega-urban structures facing generations of problems and struggling to survive as a whole.
Liu, Jian; Miller, William H
2011-03-14
We have reformulated and generalized our recent work [J. Liu and W. H. Miller, J. Chem. Phys. 126, 234110 (2007)] into an approach for generating a family of trajectory-based dynamics methods in the phase space formulation of quantum mechanics. The approach (equilibrium Liouville dynamics) is in the spirit of Liouville's theorem in classical mechanics. The trajectory-based dynamics is able to conserve the quantum canonical distribution for the thermal equilibrium system and approaches classical dynamics in the classical (ℏ → 0), high temperature (β → 0), and harmonic limits. Equilibrium Liouville dynamics provides the framework for the development of novel theoretical∕computational tools for studying quantum dynamical effects in large∕complex molecular systems.
Jones, Jeff A; Waller, Niels G
2015-06-01
Yuan and Chan (Psychometrika, 76, 670-690, 2011) recently showed how to compute the covariance matrix of standardized regression coefficients from covariances. In this paper, we describe a method for computing this covariance matrix from correlations. Next, we describe an asymptotic distribution-free (ADF; Browne in British Journal of Mathematical and Statistical Psychology, 37, 62-83, 1984) method for computing the covariance matrix of standardized regression coefficients. We show that the ADF method works well with nonnormal data in moderate-to-large samples using both simulated and real-data examples. R code (R Development Core Team, 2012) is available from the authors or through the Psychometrika online repository for supplementary materials.
NASA Astrophysics Data System (ADS)
Liu, Jian; Miller, William H.
2011-03-01
We have reformulated and generalized our recent work [J. Liu and W. H. Miller, J. Chem. Phys. 126, 234110 (2007)] into an approach for generating a family of trajectory-based dynamics methods in the phase space formulation of quantum mechanics. The approach (equilibrium Liouville dynamics) is in the spirit of Liouville's theorem in classical mechanics. The trajectory-based dynamics is able to conserve the quantum canonical distribution for the thermal equilibrium system and approaches classical dynamics in the classical (ℏ → 0), high temperature (β → 0), and harmonic limits. Equilibrium Liouville dynamics provides the framework for the development of novel theoretical/computational tools for studying quantum dynamical effects in large/complex molecular systems.
Diamond, J M
1973-02-23
The concepts by which MacArthur and Wilson have transformed the science of ecology in the past decade, and the results of ecological studies such as mine on New Guinea bird communities, have implications for conservation policies. For example, primary tropical rain forest, the most species-rich and ecologically complex habitat on earth, has for millions of years served as the ultimate evolutionary source of the world's dominant plant and animal groups. Throughout the tropics today, the rain forests are being destroyed at a rate such that little will be left in a few decades. When the rain forests have been reduced to isolated tracts separated by open country, the distribution of obligate rain forest species will come to resemble bird distributions on New Guinea land-bridge islands after severing of the land bridges. The smaller the tract, the more rapidly will forest species tend to disappear and be replaced by the widespread second-growth species that least need protection (13). This ominous process is illustrated by Barro Colorado Island, a former hill in Panama that became an island when construction of the Panama Canal flooded surrounding valleys to create Gatun Lake. In the succeeding 60 years several forest bird species have already disappeared from Barro Colorado and been unable to recolonize across the short intervening water gap from the forest on the nearby shore of Gatun Lake. The consequences of the species-area relation (Fig. 1) should be taken into consideration during the planning of tropical rain forest parks (13). In a geographical area that is relatively homogeneous with regard to the fauna, one large park would be preferable to an equivalent area in the form of several smaller parks. Continuous nonforest strips through the park (for example, wide highway swaths) would convert one rain forest "island" into two half-size islands and should be avoided. If other considerations require that an area be divided into several small parks, connecting them
Kok, Jasper F.
2011-01-01
Mineral dust aerosols impact Earth’s radiation budget through interactions with clouds, ecosystems, and radiation, which constitutes a substantial uncertainty in understanding past and predicting future climate changes. One of the causes of this large uncertainty is that the size distribution of emitted dust aerosols is poorly understood. The present study shows that regional and global circulation models (GCMs) overestimate the emitted fraction of clay aerosols (< 2 μm diameter) by a factor of ∼2–8 relative to measurements. This discrepancy is resolved by deriving a simple theoretical expression of the emitted dust size distribution that is in excellent agreement with measurements. This expression is based on the physics of the scale-invariant fragmentation of brittle materials, which is shown to be applicable to dust emission. Because clay aerosols produce a strong radiative cooling, the overestimation of the clay fraction causes GCMs to also overestimate the radiative cooling of a given quantity of emitted dust. On local and regional scales, this affects the magnitude and possibly the sign of the dust radiative forcing, with implications for numerical weather forecasting and regional climate predictions in dusty regions. On a global scale, the dust cycle in most GCMs is tuned to match radiative measurements, such that the overestimation of the radiative cooling of a given quantity of emitted dust has likely caused GCMs to underestimate the global dust emission rate. This implies that the deposition flux of dust and its fertilizing effects on ecosystems may be substantially larger than thought. PMID:21189304
Gritti, Fabrice; Farkas, Tivadar; Heng, Josuah; Guiochon, Georges
2011-11-11
The influence of the particle size distribution (PSD) on the band broadening and the efficiency of packed columns is investigated on both theoretical and practical viewpoints. Each of the classical contributions to mass transfer kinetics, those due to longitudinal diffusion, eddy dispersion, and solid-liquid mass transfer resistance are measured and analyzed in terms of their expected and observed intensity as a function of the PSD of mixtures of the commercially available packing materials, 5 and 3 μm Luna-C₁₈ particles (Phenomenex, Torrance, CA, USA). Six 4.6 mm × 150 mm columns were packed with different mixtures of these two materials. The efficiencies of these columns were measured for a non-retained and a retained analytes in a mixture of acetonitrile and water. The longitudinal diffusion coefficient was directly measured by the peak parking method. The solid-liquid mass transfer coefficient was measured from the combination of the peak parking method, the best model of effective diffusion coefficient and the actual PSDs of the different particle mixtures measured by Coulter counter experiments. The eddy diffusion term was measured according to a recently developed protocol, by numerical integration of the peak profiles. Our results clearly show that the PSD has no measurable impact on any of the coefficients of the van Deemter equation. On the contrary and surprisingly, adding a small fraction of large particles to a batch of small particles can improve the quality of the packing of the fine particles. Our results indirectly confirm that the success of sub-3 μm shell particles is due to the roughness of their external surface, which contributes to eliminate most of the nefarious wall effects.
NASA Astrophysics Data System (ADS)
Totani, Tomonori; Yoshii, Yuzuru; Maihara, Toshinori; Iwamuro, Fumihide; Motohara, Kentaro
2001-10-01
Galaxy counts in the K band, (J-K) colors, and apparent size distributions of faint galaxies in the Subaru Deep Field (SDF) down to K~24.5 were studied in detail. Special attention has been paid to take into account various selection effects, including the cosmological dimming of surface brightness, to avoid any systematic bias that may be the origin of controversy in previously published results. We also tried to be very careful about systematic model uncertainties; we present a comprehensive survey of these systematic uncertainties and dependence on various parameters, and we have shown that the dominant factors to determine galaxy counts in this band are cosmology and number evolution. We found that the pure luminosity evolution (PLE) model is very consistent with all the SDF data down to K~22.5, without any evidence for number or size evolution in a low-density, Λ-dominated flat universe, which is now favored by various cosmological observations. On the other hand, a number evolution of galaxies with η~2, when invoked as the luminosity conserving mergers as φ*~(1+z)η and L*~(1+z)-η for all types of galaxies, is necessary to explain the data in the Einstein-de Sitter universe. If the popular Λ-dominated universe is taken for granted, our result then gives a strong constraint on the number evolution of giant elliptical or early-type galaxies to z~1-2 that must be met by any models in the hierarchically clustering universe, since such galaxies are the dominant population in this magnitude range (K<~22.5). A number evolution with η~1 is already difficult to reconcile with the data in this universe. On the other hand, number evolution of late-type galaxies and/or dwarf galaxies, which has been suggested by previous studies of optical galaxies, is allowed from the data. In the fainter magnitude range of K>~22.5, we found a slight excess of observed counts over the prediction of the PLE model when elliptical galaxies are treated as a single population. We
ERIC Educational Resources Information Center
Williams, Jeffrey
1994-01-01
Considers the recent flood of anthologies of literary criticism and theory as exemplifications of the confluence of pedagogical concerns, economics of publishing, and other historical factors. Looks specifically at how these anthologies present theory. Cites problems with their formatting theory and proposes alternative ways of organizing theory…
A Transversely Isotropic Thermoelastic Theory
NASA Technical Reports Server (NTRS)
Arnold, S. M.
1989-01-01
A continuum theory is presented for representing the thermoelastic behavior of composites that can be idealized as transversely isotropic. This theory is consistent with anisotropic viscoplastic theories being developed presently at NASA Lewis Research Center. A multiaxial statement of the theory is presented, as well as plane stress and plane strain reductions. Experimental determination of the required material parameters and their theoretical constraints are discussed. Simple homogeneously stressed elements are examined to illustrate the effect of fiber orientation on the resulting strain distribution. Finally, the multiaxial stress-strain relations are expressed in matrix form to simplify and accelerate implementation of the theory into structural analysis codes.
In defence of the right shift theory.
Annett, M
1996-02-01
The right shift (RS) theory of a gene for left-cerebral dominance which increases the probability of right-handedness is outlined, together with two proposed alternatives, the 1985a genetic theory of McManus and the 1993 developmental instability theory of Yeo and Gangestad. Similarities and differences among the three theories are reviewed. Both of the genetic theories can predict the distribution of handedness in families and in twins more efficiently than the developmental instability theory, and the RS theory better than the McManus theory.
Harris, Tina
2015-04-29
Grounded theory is a popular research approach in health care and the social sciences. This article provides a description of grounded theory methodology and its key components, using examples from published studies to demonstrate practical application. It aims to demystify grounded theory for novice nurse researchers, by explaining what it is, when to use it, why they would want to use it and how to use it. It should enable nurse researchers to decide if grounded theory is an appropriate approach for their research, and to determine the quality of any grounded theory research they read.
A Computability Theory for Distributed Systems.
1986-03-13
the following two elementary properties. * [p] is an equivalence relation over system computations. * For z a prefix of V, there is an event on p...assumption. C1 CO ’ We note that the two conditions in the last sentence of the theorem are not exclusive. Con-Obserration I. Any occurrence of "P" in a...Basic Tense Logic, in D. Gab- 10~th POPL (1983) 141-1,54. bay and F. Guenthner (eds.) Handbook of [MP31 Manna, Z., Pnueli, A. - Verification of Con
NASA Astrophysics Data System (ADS)
Idemoto, Yasushi; Akatsuka, Kazumasa; Kitamura, Naoto
2015-12-01
We synthesize Li(Li1/6Mn1/2Ni1/6Co1/6)O2 with a coprecipitation method, and study the electrochemical properties and the atomic configuration by means of galvanostatic charge-discharge test, neutron total scatterings, and the density functional theory calculation. From the average-structure analysis using the Bragg profile, that is, the Rietveld analysis, it is found that the sample has the Li2MnO3-type layered structure (space group; C2/m) and Ni and Co exist at both the two sites (4g and 2b sites) in the transition-metal layer. The DFT calculation indicates that there is a local atomic ordering denoted as LiMn6 in the transition-metal layer in the same way as Li2MnO3. Moreover, such a local structure can explain a reduced pair distribution function, G(r), derived from neutron total scatterings. Detailed investigation on the G(r) also suggests a local distortion along the c axis perpendicular to the layer.
NASA Astrophysics Data System (ADS)
Koch, Julian; Jensen, Karsten Høgh; Stisen, Simon
2015-02-01
The hydrological modeling community is aware that the validation of distributed hydrological models has to move beyond aggregated performance measures, like hydrograph assessment by means of Nash-Suitcliffe efficiency toward a true spatial model validation. Remote sensing facilitates continuous data and can be measured on a similar spatial scale as the predictive scale of the hydrological model thereby it can serve as suitable data for the spatial validation. The human perception is often described as a very reliable and well-trained source for pattern comparison, which this study wants to exploit. A web-based survey that is interpreted based on approximately 200 replies reflects the consensus of the human perception on map comparisons of a reference map and 12 synthetic perturbations. The resulting similarity ranking can be used as a reference to benchmark various spatial performance metrics. This study promotes Fuzzy theory as a suitable approach because it considers uncertainties related to both location and value in the simulated map. Additionally, an EOF-analysis (Empirical Orthogonal Function) is conducted to decompose the map comparison into its similarities and dissimilarities. A modeling case study serves to further examine the metrics capability to assess the goodness of fit between simulated and observed land surface temperature maps. The EOF-analysis unambiguously identifies a systematic depth to groundwater table-related model deficiency. Kappa statistic extended by Fuzziness is a suitable and commonly applied measure for map comparison. However, its apparent bias sensitivity limits it's capability as a diagnostic tool to detect the distinct deficiency.
Combined linear theory/impact theory method for analysis and design of high speed configurations
NASA Technical Reports Server (NTRS)
Brooke, D.; Vondrasek, D. V.
1980-01-01
Pressure distributions on a wing body at Mach 4.63 are calculated. The combined theory is shown to give improved predictions over either linear theory or impact theory alone. The combined theory is also applied in the inverse design mode to calculate optimum camber slopes at Mach 4.63. Comparisons with optimum camber slopes obtained from unmodified linear theory show large differences. Analysis of the results indicate that the combined theory correctly predicts the effect of thickness on the loading distributions at high Mach numbers, and that finite thickness wings optimized at high Mach numbers using unmodified linear theory will not achieve the minimum drag characteristics for which they are designed.
NASA Technical Reports Server (NTRS)
Kanerva, Pentti
1988-01-01
Theoretical models of the human brain and proposed neural-network computers are developed analytically. Chapters are devoted to the mathematical foundations, background material from computer science, the theory of idealized neurons, neurons as address decoders, and the search of memory for the best match. Consideration is given to sparse memory, distributed storage, the storage and retrieval of sequences, the construction of distributed memory, and the organization of an autonomous learning system.
Sanfilippo, Antonio P.
2005-12-27
Graph theory is a branch of discrete combinatorial mathematics that studies the properties of graphs. The theory was pioneered by the Swiss mathematician Leonhard Euler in the 18th century, commenced its formal development during the second half of the 19th century, and has witnessed substantial growth during the last seventy years, with applications in areas as diverse as engineering, computer science, physics, sociology, chemistry and biology. Graph theory has also had a strong impact in computational linguistics by providing the foundations for the theory of features structures that has emerged as one of the most widely used frameworks for the representation of grammar formalisms.
Dufwenberg, Martin
2011-03-01
Game theory is a toolkit for examining situations where decision makers influence each other. I discuss the nature of game-theoretic analysis, the history of game theory, why game theory is useful for understanding human psychology, and why game theory has played a key role in the recent explosion of interest in the field of behavioral economics. WIREs Cogni Sci 2011 2 167-173 DOI: 10.1002/wcs.119 For further resources related to this article, please visit the WIREs website.
NASA Astrophysics Data System (ADS)
Solari, Soren; Smith, Andrew; Minnett, Rupert; Hecht-Nielsen, Robert
2008-06-01
Confabulation Theory [Hecht-Nielsen R. Confabulation theory. Springer-Verlag; 2007] is the first comprehensive theory of human and animal cognition. Here, we briefly describe Confabulation Theory and discuss experimental results that suggest the theory is correct. Simply put, Confabulation Theory proposes that thinking is like moving. In humans, the theory postulates that there are roughly 4000 thalamocortical modules, the “muscles of thought”. Each module performs an internal competition ( confabulation) between its symbols, influenced by inputs delivered via learned axonal associations with symbols in other modules. In each module, this competition is controlled, as in an individual muscle, by a single graded (i.e., analog) thought control signal. The final result of this confabulation process is a single active symbol, the expression of which also results in launching of action commands that trigger and control subsequent movements and/or thought processes. Modules are manipulated in groups under coordinated, event-contingent control, in a similar manner to our 700 muscles. Confabulation Theory hypothesizes that the control of thinking is a direct evolutionary outgrowth of the control of movement. Establishing a complete understanding of Confabulation Theory will require launching and sustaining a massive new phalanx of confabulation neuroscience research.
Distributed Cognition and Distributed Morality: Agency, Artifacts and Systems.
Heersmink, Richard
2017-04-01
There are various philosophical approaches and theories describing the intimate relation people have to artifacts. In this paper, I explore the relation between two such theories, namely distributed cognition and distributed morality theory. I point out a number of similarities and differences in these views regarding the ontological status they attribute to artifacts and the larger systems they are part of. Having evaluated and compared these views, I continue by focussing on the way cognitive artifacts are used in moral practice. I specifically conceptualise how such artifacts (a) scaffold and extend moral reasoning and decision-making processes, (b) have a certain moral status which is contingent on their cognitive status, and (c) whether responsibility can be attributed to distributed systems. This paper is primarily written for those interested in the intersection of cognitive and moral theory as it relates to artifacts, but also for those independently interested in philosophical debates in extended and distributed cognition and ethics of (cognitive) technology.
NASA Astrophysics Data System (ADS)
Curtright, Thomas
2002-07-01
New features are described for models with multi-particle area-dependent potentials, in any number of dimensions. The corresponding many-body field theories are investigated for classical configurations. Some explicit solutions are given, and some conjectures are made about chaos in such field theories.
Schooling and Income Distribution
ERIC Educational Resources Information Center
Marin, Alan; Psacharopoulos, George
1976-01-01
Analyzes the relationship between years of schooling and income distribution, based on human capital theory. (Available from North-Holland Publishing Company, P.O. Box 211, Amsterdam, the Netherlands; $13.50 annually, plus $4.00 postage and handling) (JG)
Vlad, Marcel Ovidiu; Ross, John
2002-12-01
We introduce a general method for the systematic derivation of nonlinear reaction-diffusion equations with distributed delays. We study the interactions among different types of moving individuals (atoms, molecules, quasiparticles, biological organisms, etc). The motion of each species is described by the continuous time random walk theory, analyzed in the literature for transport problems, whereas the interactions among the species are described by a set of transformation rates, which are nonlinear functions of the local concentrations of the different types of individuals. We use the time interval between two jumps (the transition time) as an additional state variable and obtain a set of evolution equations, which are local in time. In order to make a connection with the transport models used in the literature, we make transformations which eliminate the transition time and derive a set of nonlocal equations which are nonlinear generalizations of the so-called generalized master equations. The method leads under different specified conditions to various types of nonlocal transport equations including a nonlinear generalization of fractional diffusion equations, hyperbolic reaction-diffusion equations, and delay-differential reaction-diffusion equations. Thus in the analysis of a given problem we can fit to the data the type of reaction-diffusion equation and the corresponding physical and kinetic parameters. The method is illustrated, as a test case, by the study of the neolithic transition. We introduce a set of assumptions which makes it possible to describe the transition from hunting and gathering to agriculture economics by a differential delay reaction-diffusion equation for the population density. We derive a delay evolution equation for the rate of advance of agriculture, which illustrates an application of our analysis.
Modeling Second Language Change Using Skill Retention Theory
2013-06-01
Second language learning explored: SLA theories across nine contemporary theories . In B. VanPatten & J. Williams (Eds.), Theories in second ...mangngyrlngglrnngprgrm/correspo ndenceofproficiencysca.htm Spolsky, B. (1985). Formulating a theory of second language learning . Studies in Second ...public release; distribution is unlimited MODELING SECOND LANGUAGE CHANGE USING SKILL RETENTION THEORY by Samuel R.
Empirical Laws, Theory Construction and Bibliometrics.
ERIC Educational Resources Information Center
O'Connor, Daniel O.; Voos, Henry
1981-01-01
Examines the properties of bibliometric distributions (application of mathematics and statistical methods to books and other written communications) in a nontechnical manner, covering similarities of the Lotka, Bradford, and Zipf distributions, the relationship between empirical laws and theories, and bibliometric concepts and theory construction.…
2014-10-03
introduce distributed logics. Distributed logics lift the distribution structure of a distributed system directly into the logic, thereby parameterizing...the logic by the distribution structure itself. Each domain supports a “local modal logic.” The connections between domains are realized as...There are also multi- agent logic systems [12]. What distinguishes distributed logics from these are that the morphisms, i.e., the nbd maps, have
Circuit theory of non-equilibrium superconductivity
NASA Astrophysics Data System (ADS)
Nazarov, Yuli V.
2001-04-01
We give here a short account of a recently developed circuit theory of superconductivity. The theory accounts for decoherence between electrons and holes, twofold nature of the distribution function in the superconducting state and includes arbitrary connectors. We give a simple example and discuss numerical implementation of the theory.
NASA Technical Reports Server (NTRS)
Wolpert, David H.
2005-01-01
Probability theory governs the outcome of a game; there is a distribution over mixed strat.'s, not a single "equilibrium". To predict a single mixed strategy must use our loss function (external to the game's players. Provides a quantification of any strategy's rationality. Prove rationality falls as cost of computation rises (for players who have not previously interacted). All extends to games with varying numbers of players.
ERIC Educational Resources Information Center
Koschmann, Timothy; Roschelle, Jeremy; Nardi, Bonnie A.
1998-01-01
Includes three articles that discuss activity theory, based on "Context and Consciousness." Topics include human-computer interaction; computer interfaces; hierarchical structuring; mediation; contradictions and development; failure analysis; and designing educational technology. (LRW)
Statistical Physics for Adaptive Distributed Control
NASA Technical Reports Server (NTRS)
Wolpert, David H.
2005-01-01
A viewgraph presentation on statistical physics for distributed adaptive control is shown. The topics include: 1) The Golden Rule; 2) Advantages; 3) Roadmap; 4) What is Distributed Control? 5) Review of Information Theory; 6) Iterative Distributed Control; 7) Minimizing L(q) Via Gradient Descent; and 8) Adaptive Distributed Control.
Novel circuit theory of Andreev reflection
NASA Astrophysics Data System (ADS)
Nazarov, Yuli V.
1999-05-01
We review here a novel circuit theory of superconductivity. The existing circuit theory of Andreev reflection has been revised to account for decoherence between electrons and holes and the twofold nature of the distribution function. The description of arbitrary connectors has been elaborated on. In this way one can cope with most of the factors that limited the applicability of the old circuit theory. We give a simple example and discuss numerical implementation of the theory.
Effective theories of universal theories
Wells, James D.; Zhang, Zhengkang
2016-01-20
It is well-known but sometimes overlooked that constraints on the oblique parameters (most notably S and T parameters) are generally speaking only applicable to a special class of new physics scenarios known as universal theories. The oblique parameters should not be associated with Wilson coefficients in a particular operator basis in the effective field theory (EFT) framework, unless restrictions have been imposed on the EFT so that it describes universal theories. Here, we work out these restrictions, and present a detailed EFT analysis of universal theories. We find that at the dimension-6 level, universal theories are completely characterized by 16more » parameters. They are conveniently chosen to be: 5 oblique parameters that agree with the commonly-adopted ones, 4 anomalous triple-gauge couplings, 3 rescaling factors for the h3, hff, hV V vertices, 3 parameters for hV V vertices absent in the Standard Model, and 1 four-fermion coupling of order yf2. Furthermore, all these parameters are defined in an unambiguous and basis-independent way, allowing for consistent constraints on the universal theories parameter space from precision electroweak and Higgs data.« less
Effective theories of universal theories
Wells, James D.; Zhang, Zhengkang
2016-01-20
It is well-known but sometimes overlooked that constraints on the oblique parameters (most notably S and T parameters) are generally speaking only applicable to a special class of new physics scenarios known as universal theories. The oblique parameters should not be associated with Wilson coefficients in a particular operator basis in the effective field theory (EFT) framework, unless restrictions have been imposed on the EFT so that it describes universal theories. Here, we work out these restrictions, and present a detailed EFT analysis of universal theories. We find that at the dimension-6 level, universal theories are completely characterized by 16 parameters. They are conveniently chosen to be: 5 oblique parameters that agree with the commonly-adopted ones, 4 anomalous triple-gauge couplings, 3 rescaling factors for the h^{3}, hff, hV V vertices, 3 parameters for hV V vertices absent in the Standard Model, and 1 four-fermion coupling of order yf^{2}. Furthermore, all these parameters are defined in an unambiguous and basis-independent way, allowing for consistent constraints on the universal theories parameter space from precision electroweak and Higgs data.
Conference on Operator Theory, Wavelet Theory and Control Theory
1993-09-30
Bourbaki 662 (1985-1986). [9] Meyer, Y., Ondelettes et operateurs I, Hermann editeurs des sciences et des arts, 1990. [10] Natanson, I. P., Theory of...OPERATOR THEORY , WAVELET THEORY & CONTROL THEORY (U)F 6. AUTHOR(S) 2304/ES Professor Xingde Dai F49620-93-1-0180 7. PERFORMING ORGANIZATION NAME(S) AND...1STRIBUTION IS UNLIMITED UTL 13. ABSTRACT (Maximum 200 words) The conference on Interaction Between Operator Theory , Wavelet Theory and Control Theory
Effects of Mixtures on Liquid and Solid Fragment Size Distributions
2016-05-01
distributions, Grady- Kipp distributions, Simmons root normal distribution, maximum entropy theory, Grady’s law, mining, milling, orbital debris , hypervelocity...mining and excavation; materials processing such as milling, grinding, and crushing; orbital debris from artificial satellites including collisional
Estimating Bias Error Distributions
NASA Technical Reports Server (NTRS)
Liu, Tian-Shu; Finley, Tom D.
2001-01-01
This paper formulates the general methodology for estimating the bias error distribution of a device in a measuring domain from less accurate measurements when a minimal number of standard values (typically two values) are available. A new perspective is that the bias error distribution can be found as a solution of an intrinsic functional equation in a domain. Based on this theory, the scaling- and translation-based methods for determining the bias error distribution arc developed. These methods are virtually applicable to any device as long as the bias error distribution of the device can be sufficiently described by a power series (a polynomial) or a Fourier series in a domain. These methods have been validated through computational simulations and laboratory calibration experiments for a number of different devices.
ERIC Educational Resources Information Center
Sferra, Bobbie A.; Paddock, Susan C.
This booklet describes various theoretical aspects of leadership, including the proper exercise of authority, effective delegation, goal setting, exercise of control, assignment of responsibility, performance evaluation, and group process facilitation. It begins by describing the evolution of general theories of leadership from historic concepts…
Random matrix theory within superstatistics.
Abul-Magd, A Y
2005-12-01
We propose a generalization of the random matrix theory following the basic prescription of the recently suggested concept of superstatistics. Spectral characteristics of systems with mixed regular-chaotic dynamics are expressed as weighted averages of the corresponding quantities in the standard theory assuming that the mean level spacing itself is a stochastic variable. We illustrate the method by calculating the level density, the nearest-neighbor-spacing distributions, and the two-level correlation functions for systems in transition from order to chaos. The calculated spacing distribution fits the resonance statistics of random binary networks obtained in a recent numerical experiment.
Information Theory - The Bridge Connecting Bounded Rational Game Theory and Statistical Physics
NASA Technical Reports Server (NTRS)
Wolpert, David H.
2005-01-01
A long-running difficulty with conventional game theory has been how to modify it to accommodate the bounded rationality of all red-world players. A recurring issue in statistical physics is how best to approximate joint probability distributions with decoupled (and therefore far more tractable) distributions. This paper shows that the same information theoretic mathematical structure, known as Product Distribution (PD) theory, addresses both issues. In this, PD theory not only provides a principle formulation of bounded rationality and a set of new types of mean field theory in statistical physics; it also shows that those topics are fundamentally one and the same.
Algebraic Theories and (Infinity,1)-Categories
NASA Astrophysics Data System (ADS)
Cranch, James
2010-11-01
We adapt the classical framework of algebraic theories to work in the setting of (infinity,1)-categories developed by Joyal and Lurie. This gives a suitable approach for describing highly structured objects from homotopy theory. A central example, treated at length, is the theory of E_infinity spaces: this has a tidy combinatorial description in terms of span diagrams of finite sets. We introduce a theory of distributive laws, allowing us to describe objects with two distributing E_infinity stuctures. From this we produce a theory of E_infinity ring spaces. We also study grouplike objects, and produce theories modelling infinite loop spaces (or connective spectra), and infinite loop spaces with coherent multiplicative structure (or connective ring spectra). We use this to construct the units of a grouplike E_infinity ring space in a natural manner. Lastly we provide a speculative pleasant description of the K-theory of monoidal quasicategories and quasicategories with ring-like structures.
MFIX documentation theory guide
Syamlal, M.; Rogers, W.; O`Brien, T.J.
1993-12-01
This report describes the MFIX (Multiphase Flow with Interphase exchanges) computer model. MFIX is a general-purpose hydrodynamic model that describes chemical reactions and heat transfer in dense or dilute fluid-solids flows, flows typically occurring in energy conversion and chemical processing reactors. MFIX calculations give detailed information on pressure, temperature, composition, and velocity distributions in the reactors. With such information, the engineer can visualize the conditions in the reactor, conduct parametric studies and what-if experiments, and, thereby, assist in the design process. The MFIX model, developed at the Morgantown Energy Technology Center (METC), has the following capabilities: mass and momentum balance equations for gas and multiple solids phases; a gas phase and two solids phase energy equations; an arbitrary number of species balance equations for each of the phases; granular stress equations based on kinetic theory and frictional flow theory; a user-defined chemistry subroutine; three-dimensional Cartesian or cylindrical coordinate systems; nonuniform mesh size; impermeable and semi-permeable internal surfaces; user-friendly input data file; multiple, single-precision, binary, direct-access, output files that minimize disk storage and accelerate data retrieval; and extensive error reporting. This report, which is Volume 1 of the code documentation, describes the hydrodynamic theory used in the model: the conservation equations, constitutive relations, and the initial and boundary conditions. The literature on the hydrodynamic theory is briefly surveyed, and the bases for the different parts of the model are highlighted.
NASA Technical Reports Server (NTRS)
Chiu, Huei-Huang
1989-01-01
A theoretical method is being developed by which the structure of a radiation field can be predicted by a radiation potential theory, similar to a classical potential theory. The introduction of a scalar potential is justified on the grounds that the spectral intensity vector is irrotational. The vector is also solenoidal in the limits of a radiation field in complete radiative equilibrium or in a vacuum. This method provides an exact, elliptic type equation that will upgrade the accuracy and the efficiency of the current CFD programs required for the prediction of radiation and flow fields. A number of interesting results emerge from the present study. First, a steady state radiation field exhibits an optically modulated inverse square law distribution character. Secondly, the unsteady radiation field is structured with two conjugate scalar potentials. Each is governed by a Klein-Gordon equation with a frictional force and a restoring force. This steady potential field structure and the propagation of radiation potentials are consistent with the well known results of classical electromagnetic theory. The extension of the radiation potential theory for spray combustion and hypersonic flow is also recommended.
Theory Survey or Survey Theory?
ERIC Educational Resources Information Center
Dean, Jodi
2010-01-01
Matthew Moore's survey of political theorists in U.S. American colleges and universities is an impressive contribution to political science (Moore 2010). It is the first such survey of political theory as a subfield, the response rate is very high, and the answers to the survey questions provide new information about how political theorists look…
Fleeson, William; Jayawickreme, Eranda
2014-01-01
Personality researchers should modify models of traits to include mechanisms of differential reaction to situations. Whole Trait Theory does so via five main points. First, the descriptive side of traits should be conceptualized as density distributions of states. Second, it is important to provide an explanatory account of the Big 5 traits. Third, adding an explanatory account to the Big 5 creates two parts to traits, an explanatory part and a descriptive part, and these two parts should be recognized as separate entities that are joined into whole traits. Fourth, Whole Trait Theory proposes that the explanatory side of traits consists of social-cognitive mechanisms. Fifth, social-cognitive mechanisms that produce Big-5 states should be identified. PMID:26097268
Superpositions of probability distributions
NASA Astrophysics Data System (ADS)
Jizba, Petr; Kleinert, Hagen
2008-09-01
Probability distributions which can be obtained from superpositions of Gaussian distributions of different variances v=σ2 play a favored role in quantum theory and financial markets. Such superpositions need not necessarily obey the Chapman-Kolmogorov semigroup relation for Markovian processes because they may introduce memory effects. We derive the general form of the smearing distributions in v which do not destroy the semigroup property. The smearing technique has two immediate applications. It permits simplifying the system of Kramers-Moyal equations for smeared and unsmeared conditional probabilities, and can be conveniently implemented in the path integral calculus. In many cases, the superposition of path integrals can be evaluated much easier than the initial path integral. Three simple examples are presented, and it is shown how the technique is extended to quantum mechanics.
1980-06-25
new experiments at 30 m ( 4 ATA) is appropriate for comparing N2 and He with respect to half times and surfacing ratios. Table 4 demonstrates the...THEORY C4 i t44 4 ’I9 41-*1 ai4 p80 7 10 009 UM"tUBNC*nm N4MDOf 29WS (DT) 6-25-80 The Seventeenth Undersea Medical Society Workshop DECOMPRESSION...Hamilton, Jr., Ph.D. Edward L Beckman, M.D. Hamilton Research Ltd. University of Hawaii 80 Grove Street School of Medicine Tarrytown, New York 10591
Wavelet theory and its applications
Faber, V.; Bradley, JJ.; Brislawn, C.; Dougherty, R.; Hawrylycz, M.
1996-07-01
This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). We investigated the theory of wavelet transforms and their relation to Laboratory applications. The investigators have had considerable success in the past applying wavelet techniques to the numerical solution of optimal control problems for distributed- parameter systems, nonlinear signal estimation, and compression of digital imagery and multidimensional data. Wavelet theory involves ideas from the fields of harmonic analysis, numerical linear algebra, digital signal processing, approximation theory, and numerical analysis, and the new computational tools arising from wavelet theory are proving to be ideal for many Laboratory applications. 10 refs.
Feature-Based Binding and Phase Theory
ERIC Educational Resources Information Center
Antonenko, Andrei
2012-01-01
Current theories of binding cannot provide a uniform account for many facts associated with the distribution of anaphors, such as long-distance binding effects and the subject-orientation of monomorphemic anaphors. Further, traditional binding theory is incompatible with minimalist assumptions. In this dissertation I propose an analysis of…
Theory of multiphoton ionization of atoms
Szoeke, A.
1986-03-01
A non-perturbative approach to the theory of multiphoton ionization is reviewed. Adiabatic Floquet theory is its first approximation. It explains qualitatively the energy and angular distribution of photoelectrons. In many-electron atoms it predicts collective and inner shell excitation. 14 refs.
NASA Astrophysics Data System (ADS)
Stell, George
In recent years the properties of percolation models have been studied intensively. The purpose of our project was to develop a general theory of percolation and clustering between particles of arbitrary size and shape, with arbitrary correlations between them. The goal of such a theory includes the treatment of continuum percolation as well as a novel treatment of lattice percolation. We made substantial progress toward this goal. The quantities basic to a description of clustering, the mean cluster size, mean number of clusters, etc., were developed. Concise formulas were given for the terms in such series, and proved, at least for sufficiently low densities, that the series are absolutely convergent. These series can now be used to construct Pade approximants that will allow one to probe the percolation transition. A scaled-particle theory of percolation was developed which gives analytic approximants for the mean number of clusters in a large class of two and three dimensional percolation models. Although this quantity is essential in many applications, e.g., explaining colligative properties, and interpreting low-angle light-scattering data, no systematic studies of it have been done before this work. Recently carried out detailed computer simulations show that the mean number of clusters is given to high accuracy by several of there approximations. Extensions of this work will allow calculation of the complete cluster size distribution.
NASA Astrophysics Data System (ADS)
Karkheck, John; Stell, George
1981-08-01
A kinetic mean-field theory for the evolution of the one-particle distribution function is derived from maximizing the entropy. For a potential with a hard-sphere core plus tail, the resulting theory treats the hard-core part as in the revised Enskog theory. The tail, weighted by the hard-sphere pair distribution function, appears linearly in a mean-field term. The kinetic equation is accompanied by an entropy functional for which an H theorem was proven earlier. The revised Enskog theory is obtained by setting the potential tail to zero, the Vlasov equation is obtained by setting the hard-sphere diameter to zero, and an equation of the Enskog-Vlasov type is obtained by effecting the Kac limit on the potential tail. At equilibrium, the theory yields a radial distribution function that is given by the hard-sphere reference system and thus furnishes through the internal energy a thermodynamic description which is exact to first order in inverse temperature. A second natural route to thermodynamics (from the momentum flux which yields an approximate equation of state) gives somewhat different results; both routes coincide and become exact in the Kac limit. Our theory furnishes a conceptual basis for the association in the heuristically based modified Enskog theory (MET) of the contact value of the radial distribution function with the ''thermal pressure'' since this association follows from our theory (using either route to thermodynamics) and moreover becomes exact in the Kac limit. Our transport theory is readily extended to the general case of a soft repulsive core, e.g., as exhibited by the Lennard-Jones potential, via by-now-standard statistical-mechanical methods involving an effective hard-core potential, thus providing a self-contained statistical-mechanical basis for application to such potentials that is lacking in the standard versions of the MET. We obtain very good agreement with experiment for the thermal conductivity and shear viscosity of several
Sparse distributed memory overview
NASA Technical Reports Server (NTRS)
Raugh, Mike
1990-01-01
The Sparse Distributed Memory (SDM) project is investigating the theory and applications of massively parallel computing architecture, called sparse distributed memory, that will support the storage and retrieval of sensory and motor patterns characteristic of autonomous systems. The immediate objectives of the project are centered in studies of the memory itself and in the use of the memory to solve problems in speech, vision, and robotics. Investigation of methods for encoding sensory data is an important part of the research. Examples of NASA missions that may benefit from this work are Space Station, planetary rovers, and solar exploration. Sparse distributed memory offers promising technology for systems that must learn through experience and be capable of adapting to new circumstances, and for operating any large complex system requiring automatic monitoring and control. Sparse distributed memory is a massively parallel architecture motivated by efforts to understand how the human brain works. Sparse distributed memory is an associative memory, able to retrieve information from cues that only partially match patterns stored in the memory. It is able to store long temporal sequences derived from the behavior of a complex system, such as progressive records of the system's sensory data and correlated records of the system's motor controls.
NASA Technical Reports Server (NTRS)
Denning, Peter J.
1989-01-01
Sparse distributed memory was proposed be Pentti Kanerva as a realizable architecture that could store large patterns and retrieve them based on partial matches with patterns representing current sensory inputs. This memory exhibits behaviors, both in theory and in experiment, that resemble those previously unapproached by machines - e.g., rapid recognition of faces or odors, discovery of new connections between seemingly unrelated ideas, continuation of a sequence of events when given a cue from the middle, knowing that one doesn't know, or getting stuck with an answer on the tip of one's tongue. These behaviors are now within reach of machines that can be incorporated into the computing systems of robots capable of seeing, talking, and manipulating. Kanerva's theory is a break with the Western rationalistic tradition, allowing a new interpretation of learning and cognition that respects biology and the mysteries of individual human beings.
Arifin; Puripat, Maneeporn; Yokogawa, Daisuke; Parasuk, Vudhichai; Irle, Stephan
2016-01-30
Isomerization and transformation of glucose and fructose to 5-hydroxymethylfurfural (HMF) in both ionic liquids (ILs) and water has been studied by the reference interaction site model self-consistent field spatial electron density distribution (RISM-SCF-SEDD) method coupled with ab initio electronic structure theory, namely coupled cluster single, double, and perturbative triple excitation (CCSD(T)). Glucose isomerization to fructose has been investigated via cyclic and open chain mechanisms. In water, the calculations support the cyclic mechanism of glucose isomerization; with the predicted activation free energy is 23.8 kcal mol(-1) at experimental condition. Conversely, open ring mechanism is more favorable in ILs with the energy barrier is 32.4 kcal mol(-1) . Moreover, the transformation of fructose into HMF via cyclic mechanism is reasonable; the calculated activation barriers are 16.0 and 21.5 kcal mol(-1) in aqueous and ILs solutions, respectively. The solvent effects of ILs could be explained by the decomposition of free energies and radial distribution functions of solute-solvent that are produced by RISM-SCF-SEDD.
The Distribution of Segregation in Atlanta
ERIC Educational Resources Information Center
Meade, Anthony
1972-01-01
A prediction from ecological theory relating the distribution of residential segregation between inner and outer zones of a metropolitan area to conditions of population growth, expansion, etc. was tested using 1960 data on the Atlanta standard metropolitan statistical area. (JM)
NASA Astrophysics Data System (ADS)
Riyopoulos, Spilios
1996-03-01
A guiding center fluid theory is applied to model steady-state, single mode, high-power magnetron operation. A hub of uniform, prescribed density, feeds the current spokes. The spoke charge follows from the continuity equation and the incompressibility of the guiding center flow. Included are the spoke self-fields (DC and AC), obtained by an expansion around the unperturbed (zero-spoke charge) flow in powers of ν/V1, ν, and V1 being the effective charge density and AC amplitude. The spoke current is obtained as a nonlinear function of the detuning from the synchronous (Buneman-Hartree, BH) voltage Vs; the spoke charge is included in the self-consistent definition of Vs. It is shown that there is a DC voltage region of width ‖V-Vs‖˜V1, where the spoke width is constant and the spoke current is simply proportional to the AC voltage. The magnetron characteristic curves are ``flat'' in that range, and are approximated by a linear expansion around Vs. The derived formulas differ from earlier results [J. F. Hull, in Cross Field Microwave Devices, edited by E. Okress (Academic, New York, 1961), pp. 496-527] in (a) there is no current cutoff at synchronism; the tube operates well below as well above the BH voltage; (b) the characteristics are single valued within the synchronous voltage range; (c) the hub top is not treated as virtual cathode; and (d) the hub density is not equal to the Brillouin density; comparisons with tube measurements show the best agreement for hub density near half the Brillouin density. It is also shown that at low space charge and low power the gain curve is symmetric relative to the voltage (frequency) detuning. While symmetry is broken at high-power/high space charge magnetron operation, the BH voltage remains between the current cutoff voltages.
Quantum theory of positronium formation at surfaces
Shindo, S.; Ishii, A.
1987-06-01
A quantum-mechanical theory of positronium formation at surfaces is presented. The neutralization probability of positrons implanted into solids escaping from a surface is calculated. The theory of the resonant neutralization of ions at a surface is improved for positrons by taking into account the quantum effect of the motion of the positrons near the surface. The angular distributions and the energy distributions of the emitted positronium are calculated. We give the relationship of the positronium energy distribution and the density of states at the surface.
Analyzing Test-Taking Behavior: Decision Theory Meets Psychometric Theory.
Budescu, David V; Bo, Yuanchao
2015-12-01
We investigate the implications of penalizing incorrect answers to multiple-choice tests, from the perspective of both test-takers and test-makers. To do so, we use a model that combines a well-known item response theory model with prospect theory (Kahneman and Tversky, Prospect theory: An analysis of decision under risk, Econometrica 47:263-91, 1979). Our results reveal that when test-takers are fully informed of the scoring rule, the use of any penalty has detrimental effects for both test-takers (they are always penalized in excess, particularly those who are risk averse and loss averse) and test-makers (the bias of the estimated scores, as well as the variance and skewness of their distribution, increase as a function of the severity of the penalty).
ERIC Educational Resources Information Center
Ryland, Jane N.
1988-01-01
The microcomputer revolution, in which small and large computers have gained tremendously in capability, has created a distributed computing environment. This circumstance presents administrators with the opportunities and the dilemmas of choosing appropriate computing resources for each situation. (Author/MSE)
NASA Astrophysics Data System (ADS)
Suhov, Y.
We begin with the definition of information gained by knowing that an event A has occurred: iota (A) = -log_2 {{P}}(A). (A dual point of view is also useful (although more evasive), where iota (A) is the amount of information needed to specify event A.) Here and below {{P}} stands for the underlying probability distribution. So the rarer an event A, the more information we gain if we know it has occurred. (More broadly, the rarer an event A, the more impact it will have. For example, the unlikely event that occurred in 1938 when fishermen caught a coelacanth - a prehistoric fish believed to be extinct - required a significant change to beliefs about evolution and biology. On the other hand, the likely event of catching a herring or a tuna would hardly imply any change in theories.)
Testing reveals proppant distribution
Crump, J.B. ); Ekstrand, B.B. ); Almond, S.W. )
1988-10-31
Sand distribution tests, undertaken to answer inquiries from a producing company, have shown that proppant placed during a hydraulic fracture treatment is evenly distributed into the perforated interval. Therefore, for planning purposes, a good assumption is that all perforations will pass essentially equal volumes of proppant, provided perforation quality is uniform, perforations are open, and bottom hole treating pressure is constant across the interval. Under simulated conditions, a fluid viscosity of 30 cp (511 sec/sup -1/) allowed 20/40 sand to ''turn to corner'' and pass through perforations with minimal stratification. This finding refutes the theory held by some that the bottom perforation is ''slugged'' with heavier concentration of sand than the upper perforations, and the theory's logical extension that after the bottom perforation is filled, it plugs and the perforation just above becomes the next bottom until the entire perforated interval is screened out. Tests described in this article were part of a program implemented to analyze causes of screen outs encountered in fracturing operations.
Decidability of formal theories and hyperincursivity theory
NASA Astrophysics Data System (ADS)
Grappone, Arturo G.
2000-05-01
This paper shows the limits of the Proof Standard Theory (briefly, PST) and gives some ideas of how to build a proof anticipatory theory (briefly, PAT) that has no such limits. Also, this paper considers that Gödel's proof of the undecidability of Principia Mathematica formal theory is not valid for axiomatic theories that use a PAT to build their proofs because the (hyper)incursive functions are self-representable.
Thermodynamic theory of equilibrium fluctuations
Mishin, Y.
2015-12-15
The postulational basis of classical thermodynamics has been expanded to incorporate equilibrium fluctuations. The main additional elements of the proposed thermodynamic theory are the concept of quasi-equilibrium states, a definition of non-equilibrium entropy, a fundamental equation of state in the entropy representation, and a fluctuation postulate describing the probability distribution of macroscopic parameters of an isolated system. Although these elements introduce a statistical component that does not exist in classical thermodynamics, the logical structure of the theory is different from that of statistical mechanics and represents an expanded version of thermodynamics. Based on this theory, we present a regular procedure for calculations of equilibrium fluctuations of extensive parameters, intensive parameters and densities in systems with any number of fluctuating parameters. The proposed fluctuation formalism is demonstrated by four applications: (1) derivation of the complete set of fluctuation relations for a simple fluid in three different ensembles; (2) fluctuations in finite-reservoir systems interpolating between the canonical and micro-canonical ensembles; (3) derivation of fluctuation relations for excess properties of grain boundaries in binary solid solutions, and (4) derivation of the grain boundary width distribution for pre-melted grain boundaries in alloys. The last two applications offer an efficient fluctuation-based approach to calculations of interface excess properties and extraction of the disjoining potential in pre-melted grain boundaries. Possible future extensions of the theory are outlined.
Grounded theory, feminist theory, critical theory: toward theoretical triangulation.
Kushner, Kaysi Eastlick; Morrow, Raymond
2003-01-01
Nursing and social science scholars have examined the compatibility between feminist and grounded theory traditions in scientific knowledge generation, concluding that they are complementary, yet not without certain tensions. This line of inquiry is extended to propose a critical feminist grounded theory methodology. The construction of symbolic interactionist, feminist, and critical feminist variants of grounded theory methodology is examined in terms of the presuppositions of each tradition and their interplay as a process of theoretical triangulation.
Foundations for a theory of gravitation theories
NASA Technical Reports Server (NTRS)
Thorne, K. S.; Lee, D. L.; Lightman, A. P.
1972-01-01
A foundation is laid for future analyses of gravitation theories. This foundation is applicable to any theory formulated in terms of geometric objects defined on a 4-dimensional spacetime manifold. The foundation consists of (1) a glossary of fundamental concepts; (2) a theorem that delineates the overlap between Lagrangian-based theories and metric theories; (3) a conjecture (due to Schiff) that the Weak Equivalence Principle implies the Einstein Equivalence Principle; and (4) a plausibility argument supporting this conjecture for the special case of relativistic, Lagrangian-based theories.
Five-Parameter Bivariate Probability Distribution
NASA Technical Reports Server (NTRS)
Tubbs, J.; Brewer, D.; Smith, O. W.
1986-01-01
NASA technical memorandum presents four papers about five-parameter bivariate gamma class of probability distributions. With some overlap of subject matter, papers address different aspects of theories of these distributions and use in forming statistical models of such phenomena as wind gusts. Provides acceptable results for defining constraints in problems designing aircraft and spacecraft to withstand large wind-gust loads.
Structure and thermodynamics of core-softened models for alcohols
Munaò, Gianmarco; Urbic, Tomaz
2015-06-07
The phase behavior and the fluid structure of coarse-grain models for alcohols are studied by means of reference interaction site model (RISM) theory and Monte Carlo simulations. Specifically, we model ethanol and 1-propanol as linear rigid chains constituted by three (trimers) and four (tetramers) partially fused spheres, respectively. Thermodynamic properties of these models are examined in the RISM context, by employing closed formulæ for the calculation of free energy and pressure. Gas-liquid coexistence curves for trimers and tetramers are reported and compared with already existing data for a dimer model of methanol. Critical temperatures slightly increase with the number of CH{sub 2} groups in the chain, while critical pressures and densities decrease. Such a behavior qualitatively reproduces the trend observed in experiments on methanol, ethanol, and 1-propanol and suggests that our coarse-grain models, despite their simplicity, can reproduce the essential features of the phase behavior of such alcohols. The fluid structure of these models is investigated by computing radial distribution function g{sub ij}(r) and static structure factor S{sub ij}(k); the latter shows the presence of a low−k peak at intermediate-high packing fractions and low temperatures, suggesting the presence of aggregates for both trimers and tetramers.
Structure and thermodynamics of core-softened models for alcohols.
Munaò, Gianmarco; Urbic, Tomaz
2015-06-07
The phase behavior and the fluid structure of coarse-grain models for alcohols are studied by means of reference interaction site model (RISM) theory and Monte Carlo simulations. Specifically, we model ethanol and 1-propanol as linear rigid chains constituted by three (trimers) and four (tetramers) partially fused spheres, respectively. Thermodynamic properties of these models are examined in the RISM context, by employing closed formulæ for the calculation of free energy and pressure. Gas-liquid coexistence curves for trimers and tetramers are reported and compared with already existing data for a dimer model of methanol. Critical temperatures slightly increase with the number of CH2 groups in the chain, while critical pressures and densities decrease. Such a behavior qualitatively reproduces the trend observed in experiments on methanol, ethanol, and 1-propanol and suggests that our coarse-grain models, despite their simplicity, can reproduce the essential features of the phase behavior of such alcohols. The fluid structure of these models is investigated by computing radial distribution function gij(r) and static structure factor Sij(k); the latter shows the presence of a low-k peak at intermediate-high packing fractions and low temperatures, suggesting the presence of aggregates for both trimers and tetramers.
Distributed Control with Collective Intelligence
NASA Technical Reports Server (NTRS)
Wolpert, David H.; Wheeler, Kevin R.; Tumer, Kagan
1998-01-01
We consider systems of interacting reinforcement learning (RL) algorithms that do not work at cross purposes , in that their collective behavior maximizes a global utility function. We call such systems COllective INtelligences (COINs). We present the theory of designing COINs. Then we present experiments validating that theory in the context of two distributed control problems: We show that COINs perform near-optimally in a difficult variant of Arthur's bar problem [Arthur] (and in particular avoid the tragedy of the commons for that problem), and we also illustrate optimal performance in the master-slave problem.
Unification of quantum information theory
NASA Astrophysics Data System (ADS)
Abeyesinghe, Anura
We present the unification of many previously disparate results in noisy quantum Shannon theory and the unification of all of noiseless quantum Shannon theory. More specifically we deal here with bipartite, unidirectional, and memoryless quantum Shannon theory. We find all the optimal protocols and quantify the relationship between the resources used, both for the one-shot and for the ensemble case, for what is arguably the most fundamental task in quantum information theory: sharing entangled states between a sender and a receiver. We find that all of these protocols are derived from our one-shot superdense coding protocol and relate nicely to each other. We then move on to noisy quantum information theory and give a simple, direct proof of the "mother" protocol, or rather her generalization to the Fully Quantum Slepian-Wolf protocol (FQSW). FQSW simultaneously accomplishes two goals: quantum communication-assisted entanglement distillation, and state transfer from the sender to the receiver. As a result, in addition to her other "children," the mother protocol generates the state merging primitive of Horodecki, Oppenheim, and Winter as well as a new class of distributed compression protocols for correlated quantum sources, which are optimal for sources described by separable density operators. Moreover, the mother protocol described here is easily transformed into the so-called "father" protocol, demonstrating that the division of single-sender/single-receiver protocols into two families was unnecessary: all protocols in the family are children of the mother.
Forgotten and neglected theories of Poincaré
NASA Astrophysics Data System (ADS)
Arnol'd, Vladimir I.
2006-02-01
This paper describes a number of published and unpublished works of Henri Poincaré that await continuation by the next generations of mathematicians: works on celestial mechanics, on topology, on the theory of chaos and dynamical systems, and on homology, intersections and links. Also discussed are the history of the theory of relativity and the theory of generalized functions (distributions) and the connection between the Poincaré conjecture and the theory of knot invariants.
NASA Astrophysics Data System (ADS)
Bardakçı, Tayyibe; Kumru, Mustafa; Altun, Ahmet
2016-07-01
The Cu(II), Zn(II), Cd(II), and Hg(II) bromide complexes of p-toluidine have been studied with B3LYP calculations by using def2-TZVP basis set at the metal atoms and using def2-TZVP and 6-311G+(d,p) basis sets at the remaining atoms. Both basis set combinations give analogous results, which validate the use of quickly converging 6-311G+(d,p) basis set in future studies. The molecular structures, atomic charge and spin distributions, and harmonic vibrational frequencies of the complexes have been calculated. The Zn, Cd and Hg complexes have been found to have distorted tetrahedral environments around the metal atoms whereas Cu complex has a square planar geometry. The NBO charge analysis have been found more accurate and less misleading compared with the Mulliken scheme. The present vibrational spectra calculations allow accurate assignment of the vibrational bands, which otherwise assigned tentatively in previous experimental-only studies.
A new viewpoint on the ambipolar diffusion Schottky theory
Kurbatov, P. F.
2013-04-15
A modern modification of the Schottky theory is proposed. It enables overcoming some of the difficulties and contradictions of the old theory and extends its capabilities in the analysis of radial distributions of ionized species. This allows us to consider the distributions of positive column plasma in noble gas d.c. discharges within a proper universal framework. The radial distributions of plasma species are basically similar in their nature and are independent of the character and features of plasma reactions.
Lim, B S; Fomitchev, D V; Holm, R H
2001-08-13
The complexes [Ni(S2C2Me2)2](z) (z = 0, 1-, 2-) have been isolated for the purpose of investigating their electronic structures in a reversible three-member electron-transfer series. Members are interrelated by reversible redox reactions with E(1/2)(0/1-) = -0.15 V and E(1/2)(1-/2-) = -1.05 V versus SCE in acetonitrile. The three complexes have nearly planar structures of idealized D(2)(h) symmetry. As the series is traversed in the reducing direction, Ni-S and C-S bond lengths increase; the chelate ring C-C bond length decreases from the neutral complex to the monoanion and does not change significantly in the dianion. Structural trends are compared with previous results for [Ni(S2C2R2)2)](1-,2-). Following the geometrical changes, values of nu(Ni)(-)(S) and nu(C)(-)(S) decrease, while the value of nu(C)(-)(C) increases with increased reduction. Geometry optimizations at the density functional theory (DFT) level were performed for all members of the series. Geometrical parameters obtained from the calculations are in good agreement with the experimental findings. The 5b(2g) orbital was identified as the LUMO in [Ni(S2C2Me2)2], the SOMO in [Ni(S2C2Me2)2](1-), and the HOMO in [Ni(S2C2Me2)2]2-. Unlike in the situation in the [M(CO)2-(S2C2Me2)2]z series (M = Mo, W; z = 0, 1-, 2-), the apparent contribution from the metal d orbital in the electroactive orbital is not constant. In the present series, the d(xz) contribution increases from 13 to 20 to 39% upon passing from the neutral to the monoanionic to the dianionic complex. Accurate calculation of EPR g-values of [Ni(S2C2Me2)2]1- by DFT serves as a test for the reliability of the electronic structure calculations.
NASA Technical Reports Server (NTRS)
Chung, Ming-Ying; Ciardo, Gianfranco; Siminiceanu, Radu I.
2007-01-01
The Saturation algorithm for symbolic state-space generation, has been a recent break-through in the exhaustive veri cation of complex systems, in particular globally-asyn- chronous/locally-synchronous systems. The algorithm uses a very compact Multiway Decision Diagram (MDD) encoding for states and the fastest symbolic exploration algo- rithm to date. The distributed version of Saturation uses the overall memory available on a network of workstations (NOW) to efficiently spread the memory load during the highly irregular exploration. A crucial factor in limiting the memory consumption during the symbolic state-space generation is the ability to perform garbage collection to free up the memory occupied by dead nodes. However, garbage collection over a NOW requires a nontrivial communication overhead. In addition, operation cache policies become critical while analyzing large-scale systems using the symbolic approach. In this technical report, we develop a garbage collection scheme and several operation cache policies to help on solving extremely complex systems. Experiments show that our schemes improve the performance of the original distributed implementation, SmArTNow, in terms of time and memory efficiency.
Distributed Leadership and Shared Governance in Post-Secondary Education
ERIC Educational Resources Information Center
Burke, Kenneth M.
2010-01-01
Leadership in education and traditional management theory face the challenges of advancing a theory and practice for twenty-first century organization. This article approaches the potential for new frames of reference on leadership through the correlations between the emergent theory of distributed leadership and the philosophy of shared…
A Study of Marketing (Distributive) Education Research Methods.
ERIC Educational Resources Information Center
Wentland, Daniel M.
For research to be considered "valid," the research must be originally based upon a known theory. The result of research should be the expansion of known theory or the development of new theory. An examination was made of marketing (distributive) education research to determine if that research is based upon a theoretical framework and results in…
A general relaxation theory of simple liquids
NASA Technical Reports Server (NTRS)
Merilo, M.; Morgan, E. J.
1973-01-01
A relatively simple relaxation theory to account for the behavior of liquids under dynamic conditions was proposed. The general dynamical equations are similar in form to the phenomenological relaxation equations used in theories of viscoelasticity, however, they differ in that all the coefficients of the present equations are expressed in terms of thermodynamic and molecular quantities. The theory is based on the concept that flow in a liquid distorts both the radial and the velocity distribution functions, and that relaxation equations describing the return of these functions to their isotropic distributions, characterizing a stationary liquid, can be written. The theory was applied to the problems of steady and oscillatory shear flows and to the propagation of longitudinal waves. In all cases classical results are predicted for strain rates, and an expression for the viscosity of a liquid, simular to the Macedo-Litovitz equation, is obtained.
NASA Astrophysics Data System (ADS)
Banks, Tom
2008-09-01
1. Introduction; 2. Quantum theory of free scalar fields; 3. Interacting field theory; 4. Particles of spin one, and gauge invariance; 5. Spin 1/2 particles and Fermi statistics; 6. Massive quantum electrodynamics; 7. Symmetries, Ward identities and Nambu Goldstone bosons; 8. Non-abelian gauge theory; 9. Renormalization and effective field theory; 10. Instantons and solitons; 11. Concluding remarks; Appendices; References; Index.
ERIC Educational Resources Information Center
Apsche, Jack A.
2005-01-01
In his work on the Theory of Modes, Beck (1996) suggested that there were flaws with his cognitive theory. He suggested that though there are shortcomings to his cognitive theory, there were not similar shortcomings to the practice of Cognitive Therapy. The author suggests that if there are shortcomings to cognitive theory the same shortcomings…
Ward, B. F. L.
2008-01-01
We show that it is possible to improve the infrared aspects of the standard treatment of the DGLAP-CS evolution theory to take into account a large class of higher-order corrections that significantly improve the precision of the theory for any given level of fixed-order calculation of its respective kernels. We illustrate the size of the effects we resum using the moments of the parton distributions.
Quantum entanglement assisted key distribution
NASA Astrophysics Data System (ADS)
Tang, Ke; Ji, Ping; Zhang, Xiaowen
2007-04-01
Quantum correlations or entanglement is a basic ingredient for many applications of quantum information theory.One important application using quantum entanglement exploits the correlation nature of entangled photon states is quantum key distribution, which is proven unbreakable in principle and provides the highest possible security that is impossible in classical information theory. However, generating entangled photon pairs is not a simple task -- only approximately one out of a million pump photons decay into a signal and idler photon pair. This low rate of entangled photon pairs is further reduced by the overhead required in order for the rectification of the inevitable errors due to channel imperfections or caused by potential eavesdroppers. As a consequence, quantum key distribution suffers from a low bit rate, which is in the order of hundreds to thousands bits per second or below. On the other hand, the classical public key distribution does not impose a tight limit on the transmission rate. However, it is subject to the risks of eavesdroppers sitting in the middle of the insecure channel. In this paper, we propose a hybrid key distribution method which uses public key distribution method to generate a raw key, and then uses entanglement assisted communication to modify the raw key by inserting a number of quantum bits in the raw key. Building upon the foundation of the unconditional security of quantum key distribution, we use the privacy amplification to make the affection of inserted bits expand to a whole key. Our quantum entanglement assisted key distribution scheme greatly improves the efficiency of key distribution while without compromising the level of security achievable by quantum cryptography.
Nonrelativistic superstring theories
Kim, Bom Soo
2007-12-15
We construct a supersymmetric version of the critical nonrelativistic bosonic string theory [B. S. Kim, Phys. Rev. D 76, 106007 (2007).] with its manifest global symmetry. We introduce the anticommuting bc conformal field theory (CFT) which is the super partner of the {beta}{gamma} CFT. The conformal weights of the b and c fields are both 1/2. The action of the fermionic sector can be transformed into that of the relativistic superstring theory. We explicitly quantize the theory with manifest SO(8) symmetry and find that the spectrum is similar to that of type IIB superstring theory. There is one notable difference: the fermions are nonchiral. We further consider noncritical generalizations of the supersymmetric theory using the superspace formulation. There is an infinite range of possible string theories similar to the supercritical string theories. We comment on the connection between the critical nonrelativistic string theory and the lightlike linear dilaton theory.
NASA Astrophysics Data System (ADS)
Jovanović, Dejan; Barrett, Clark
The classic method of Nelson and Oppen for combining decision procedures requires the theories to be stably-infinite. Unfortunately, some important theories do not fall into this category (e.g. the theory of bit-vectors). To remedy this problem, previous work introduced the notion of polite theories. Polite theories can be combined with any other theory using an extension of the Nelson-Oppen approach. In this paper we revisit the notion of polite theories, fixing a subtle flaw in the original definition. We give a new combination theorem which specifies the degree to which politeness is preserved when combining polite theories. We also give conditions under which politeness is preserved when instantiating theories by identifying two sorts. These results lead to a more general variant of the theorem for combining multiple polite theories.
Quantum Theory is an Information Theory
NASA Astrophysics Data System (ADS)
D'Ariano, Giacomo M.; Perinotti, Paolo
2016-03-01
In this paper we review the general framework of operational probabilistic theories (OPT), along with the six axioms from which quantum theory can be derived. We argue that the OPT framework along with a relaxed version of five of the axioms, define a general information theory. We close the paper with considerations about the role of the observer in an OPT, and the interpretation of the von Neumann postulate and the Schrödinger-cat paradox.
Teaching Theory X and Theory Y in Organizational Communication
ERIC Educational Resources Information Center
Noland, Carey
2014-01-01
The purpose of the activity described here is to integrate McGregor's Theory X and Theory Y into a group application: design a syllabus that embodies either Theory X or Theory Y tenets. Students should be able to differentiate between Theory X and Theory Y, create a syllabus based on Theory X or Theory Y tenets, evaluate the different syllabi…
Identity theory and personality theory: mutual relevance.
Stryker, Sheldon
2007-12-01
Some personality psychologists have found a structural symbolic interactionist frame and identity theory relevant to their work. This frame and theory, developed in sociology, are first reviewed. Emphasized in the review are a multiple identity conception of self, identities as internalized expectations derived from roles embedded in organized networks of social interaction, and a view of social structures as facilitators in bringing people into networks or constraints in keeping them out, subsequently, attention turns to a discussion of the mutual relevance of structural symbolic interactionism/identity theory and personality theory, looking to extensions of the current literature on these topics.
Information distribution in distributed microprocessor based flight control systems
NASA Technical Reports Server (NTRS)
Montgomery, R. C.; Lee, P. S.
1977-01-01
This paper presents an optimal control theory that accounts for variable time intervals in the information distribution to control effectors in a distributed microprocessor based flight control system. The theory is developed using a linear process model for the aircraft dynamics and the information distribution process is modeled as a variable time increment process where, at the time that information is supplied to the control effectors, the control effectors know the time of the next information update only in a stochastic sense. An optimal control problem is formulated and solved that provides the control law that minimizes the expected value of a quadratic cost function. An example is presented where the theory is applied to the control of the longitudinal motions of the F8-DFBW aircraft. Theoretical and simulation results indicate that, for the example problem, the optimal cost obtained using a variable time increment Markov information update process where the control effectors know only the past information update intervals and the Markov transition mechanism is almost identical to that obtained using a known uniform information update interval.
Phase-space quantization of field theory.
Curtright, T.; Zachos, C.
1999-04-20
In this lecture, a limited introduction of gauge invariance in phase-space is provided, predicated on canonical transformations in quantum phase-space. Exact characteristic trajectories are also specified for the time-propagating Wigner phase-space distribution function: they are especially simple--indeed, classical--for the quantized simple harmonic oscillator. This serves as the underpinning of the field theoretic Wigner functional formulation introduced. Scalar field theory is thus reformulated in terms of distributions in field phase-space. This is a pedagogical selection from work published and reported at the Yukawa Institute Workshop ''Gauge Theory and Integrable Models'', 26-29 January, 1999.
A Nonlinear Theory for Smart Composite Structures
NASA Technical Reports Server (NTRS)
Chattopadhyay, Aditi
2002-01-01
The paper discusses the following: (1) Development of a completely coupled thermo-piezoelectric-mechanical theory for the analysis of composite shells with segmented and distributed piezoelectric sensor/actuators and shape memory alloys. The higher order displacement theory will be used to capture the transverse shear effects in anisotropic composites. The original theory will be modified to satisfy the stress continuity at ply interfaces. (2) Development of a finite element technique to implement the mathematical model. (3) Investigation of the coupled structures/controls interaction problem to study the complex trade-offs associated with the coupled problem.
Magnetic Soliton, Homotopy and Higgs Theory,
1986-04-24
OD-AL67 366 NAGETIC SOLITON ONOTOPY ND HIGGS THEORY(U) FOREIGNI n1/ 1TECHNOLOGY D V NRIGHT-PATTERSON AFD ON Y LI ET AL. UNCLSSIIED24 APR 86 FTD-ID...MAGNETIC SOLITON, HOMOTOPY AND HIGGS THEORY by Li Yuanjie and Lei Shizu *. . * . .%..**% . . .-..C./ ~~~Approved for public release; -," Distribution...HOMOTOPY AND HIGGS THEORY By: Li Yuanjie and Lei Shizu English pages: 9 Source: Huazhong Gongxueyuan Xuebao, Vol. 11, Nr. 6, 1983, pp. 65-70 Country of
APhoRISM FP7 project: the Multi-platform volcanic Ash Cloud Estimation (MACE) infrastructure
NASA Astrophysics Data System (ADS)
Merucci, Luca; Corradini, Stefano; Bignami, Christian; Stramondo, Salvatore
2014-05-01
APHORISM is an FP7 project that aims to develop innovative products to support the management and mitigation of the volcanic and the seismic crisis. Satellite and ground measurements will be managed in a novel manner to provide new and improved products in terms of accuracy and quality of information. The Multi-platform volcanic Ash Cloud Estimation (MACE) infrastructure will exploit the complementarity between geostationary, and polar satellite sensors and ground measurements to improve the ash detection and retrieval and to fully characterize the volcanic ash clouds from source to the atmosphere. The basic idea behind the proposed method consists to manage in a novel manner, the volcanic ash retrievals at the space-time scale of typical geostationary observations using both the polar satellite estimations and in-situ measurements. The typical ash thermal infrared (TIR) retrieval will be integrated by using a wider spectral range from visible (VIS) to microwave (MW) and the ash detection will be extended also in case of cloudy atmosphere or steam plumes. All the MACE ash products will be tested on three recent eruptions representative of different eruption styles in different clear or cloudy atmospheric conditions: Eyjafjallajokull (Iceland) 2010, Grimsvotn (Iceland) 2011 and Etna (Italy) 2011-2012. The MACE infrastructure will be suitable to be implemented in the next generation of ESA Sentinels satellite missions.
Salting-out effects by pressure-corrected 3D-RISM
NASA Astrophysics Data System (ADS)
Misin, Maksim; Vainikka, Petteri A.; Fedorov, Maxim V.; Palmer, David S.
2016-11-01
We demonstrate that using a pressure corrected three-dimensional reference interaction site model one can accurately predict salting-out (Setschenow's) constants for a wide range of organic compounds in aqueous solutions of NaCl. The approach, based on classical molecular force fields, offers an alternative to more heavily parametrized methods.
Integral equation study of soft-repulsive dimeric fluids
NASA Astrophysics Data System (ADS)
Munaò, Gianmarco; Saija, Franz
2017-03-01
We study fluid structure and water-like anomalies of a system constituted by dimeric particles interacting via a purely repulsive core-softened potential by means of integral equation theories. In our model, dimers interact through a repulsive pair potential of inverse-power form with a softened repulsion strength. By employing the Ornstein–Zernike approach and the reference interaction site model (RISM) theory, we study the behavior of water-like anomalies upon progressively increasing the elongation λ of the dimers from the monomeric case (λ =0 ) to the tangent configuration (λ =1 ). For each value of the elongation we consider two different values of the interaction potential, corresponding to one and two length scales, with the aim to provide a comprehensive description of the possible fluid scenarios of this model. Our theoretical results are systematically compared with already existing or newly generated Monte Carlo data: we find that theories and simulations agree in providing the picture of a fluid exhibiting density and structural anomalies for low values of λ and for both the two values of the interaction potential. Integral equation theories give accurate predictions for pressure and radial distribution functions, whereas the temperatures where anomalies occur are underestimated. Upon increasing the elongation, the RISM theory still predicts the existence of anomalies; the latter are no longer observed in simulations, since their development is likely precluded by the onset of crystallization. We discuss our results in terms of the reliability of integral equation theories in predicting the existence of water-like anomalies in core-softened fluids.
Integral equation study of soft-repulsive dimeric fluids.
Munaò, Gianmarco; Saija, Franz
2017-03-22
We study fluid structure and water-like anomalies of a system constituted by dimeric particles interacting via a purely repulsive core-softened potential by means of integral equation theories. In our model, dimers interact through a repulsive pair potential of inverse-power form with a softened repulsion strength. By employing the Ornstein-Zernike approach and the reference interaction site model (RISM) theory, we study the behavior of water-like anomalies upon progressively increasing the elongation λ of the dimers from the monomeric case ([Formula: see text]) to the tangent configuration ([Formula: see text]). For each value of the elongation we consider two different values of the interaction potential, corresponding to one and two length scales, with the aim to provide a comprehensive description of the possible fluid scenarios of this model. Our theoretical results are systematically compared with already existing or newly generated Monte Carlo data: we find that theories and simulations agree in providing the picture of a fluid exhibiting density and structural anomalies for low values of λ and for both the two values of the interaction potential. Integral equation theories give accurate predictions for pressure and radial distribution functions, whereas the temperatures where anomalies occur are underestimated. Upon increasing the elongation, the RISM theory still predicts the existence of anomalies; the latter are no longer observed in simulations, since their development is likely precluded by the onset of crystallization. We discuss our results in terms of the reliability of integral equation theories in predicting the existence of water-like anomalies in core-softened fluids.
A theory of sequential fragmentation and its astronomical applications
Brown, W.K.
1988-11-01
This report presents a theory of sequential fragmentation that describes a cascade of fragmentation and refragmentation, i.e., continued comminution. The theory reproduces one of the two major empirical descriptors that have traditionally been used to describe the mass distributions from fragmentation experiments. Additional experimental evidence, including explosive aerosolization, grinding in a ball mill, and simulated volcanic action, further validates the theory. The report also presents some astronomical applications of the theory, including infalling extraterrestrial material, siderophile concentrations in black magnetic spherules of possible meteoritic origin, the asteroids, the distribution of galactic masses, and the initial mass function of stars. 49 refs., 14 figs., 1 tab.
General autocatalytic theory and simple model of financial markets
NASA Astrophysics Data System (ADS)
Thuy Anh, Chu; Lan, Nguyen Tri; Viet, Nguyen Ai
2015-06-01
The concept of autocatalytic theory has become a powerful tool in understanding evolutionary processes in complex systems. A generalization of autocatalytic theory was assumed by considering that the initial element now is being some distribution instead of a constant value as in traditional theory. This initial condition leads to that the final element might have some distribution too. A simple physics model for financial markets is proposed, using this general autocatalytic theory. Some general behaviours of evolution process and risk moment of a financial market also are investigated in framework of this simple model.
Generalizability Theory and Classical Test Theory
ERIC Educational Resources Information Center
Brennan, Robert L.
2011-01-01
Broadly conceived, reliability involves quantifying the consistencies and inconsistencies in observed scores. Generalizability theory, or G theory, is particularly well suited to addressing such matters in that it enables an investigator to quantify and distinguish the sources of inconsistencies in observed scores that arise, or could arise, over…
Method for Transducer Transient Suppression. I. Theory
1992-09-01
Vol. 92, No. 3, September 1992 Method for transducer transient suppression. I: Theory Jean C. Piquette Naval Research Laboratory. Underwater Sound...TITLE AND SUBTITLE 5. FUNDING NUMBERS Method for transducer transient suppression. I: Theo:y PE - 61153N TA - RROII-08-42 WU - DN220-161 6. AUTHOR(S) Jean...STATEMENT 12b. DISTRIBUTION CODE Approved for public release; distribution unlimited. 13. ABSTRACT (Maximum 200 words) The problem of driving a transducer in
Disengagement theory revisited.
Markson, E W
1975-01-01
Cumming and Henry erected the basic frame for a socio-cultural theory of normal aging in their 1961 book, Growing Old. The basic postulates of this theory are reviewed, and the overall structure of the theory briefly examined. Critical data necessary either to accept or reject disengagement theory are not yet available, although useful information has been gathered since the theory first appeared. Part of the difficulty in amassing "proof" or "disproof" is inherent in the intricate and complex nature of the aging process itself. This orienting paper introduced a set of contributtions by other commentators on disengagement theory.
NASA Astrophysics Data System (ADS)
Hughes, Richard
2004-05-01
Quantum key distribution (QKD) uses single-photon communications to generate the shared, secret random number sequences that are used to encrypt and decrypt secret communications. The unconditional security of QKD is based on the interplay between fundamental principles of quantum physics and information theory. An adversary can neither successfully tap the transmissions, nor evade detection (eavesdropping raises the key error rate above a threshold value). QKD could be particularly attractive for free-space optical communications, both ground-based and for satellites. I will describe a QKD experiment performed over multi-kilometer line-of-sight paths, which serves as a model for a satellite-to-ground key distribution system. The system uses single-photon polarization states, without active polarization switching, and for the first time implements the complete BB84 QKD protocol including, reconciliation, privacy amplification and the all-important authentication stage. It is capable of continuous operation throughout the day and night, achieving the self-sustaining production of error-free, shared, secret bits. I will also report on the results of satellite-to-ground QKD modeling.
Superstatistics: Theory and Applications
NASA Astrophysics Data System (ADS)
Beck, C.
2015-12-01
Many driven nonequilibrium systems are described by a superposition of several dynamics on various time scales. If time scales are clearly separated then the formalism of superstatistics can be applied, leading effectively to a more general statistical mechanics relevant for complex systems. In these types of systems there is often dynamical behavior that is characterized by spatio-temporal fluctuations of an intensive parameter β. This parameter may be for example the inverse temperature, or an effective friction constant, or the amplitude of Gaussian white noise, or the energy dissipation in turbulent flows, or simply a local variance parameter extracted from a measured signal. A nonhomogenoeus spatially extended system with fluctuations in β on a large time scale, larger than the local relaxation time, leads to a superstatistical description, by averaging local Boltzmann factors using a suitable weight function f(β). Kappa distributions in space plasma physics are one example which naturally follows out of this formalism, but there are many applications in other areas as well. In this talk I will sketch the basic theory underlying the superstatistical approach and then describe a couple of recent applications.
Wallace
2000-09-01
The current status of the theory of stress fluctuations is marked by two circumstances: no currently available formulas are valid for a metallic system, and a series of contradictory formulas remains unresolved. Here we derive formulas for shear- and isotropic-stress energy fluctuations, in the primary statistical mechanics ensembles. These formulas are valid for a classical monatomic system representing a metal or nonmetal, in cubic crystal, amorphous solid, or liquid phases. Current contradictions in fluctuation formulas are resolved through the following observations. First, the expansion of a dynamical variable A in terms of the fluctuations explicit in a given ensemble distribution, for example deltaA=adeltaN+bdeltaH in the grand canonical ensemble, is correct if and only if deltaA is a function only of deltaN and deltaH. The common use of this expansion has produced incorrect fluctuation formulas. Second, the thermodynamic fluctuations of Landau and Lifshitz do not correspond to statistical mechanics fluctuations, and the two types of fluctuations have essentially different values.
Kheirandish, F.; Amooshahi, M.
2008-11-18
Quantum field theory of a damped vibrating string as the simplest dissipative scalar field theory is investigated by introducing a minimal coupling method. The rate of energy flowing between the system and its environment is obtained.
Interpolation and Approximation Theory.
ERIC Educational Resources Information Center
Kaijser, Sten
1991-01-01
Introduced are the basic ideas of interpolation and approximation theory through a combination of theory and exercises written for extramural education at the university level. Topics treated are spline methods, Lagrange interpolation, trigonometric approximation, Fourier series, and polynomial approximation. (MDH)
Stabilizing bottomless action theories
NASA Astrophysics Data System (ADS)
Greensite, J.; Halpern, M. B.
1984-08-01
We show how to construct the euclidean quantum theory corresponding to classical actions which are unbounded from below. Our method preserves the classical limit, the large- N limit, and the perturbative expansion of the unstabilized theories.
NASA Technical Reports Server (NTRS)
Tollmien, W.
1949-01-01
The theory of characteristics will be presented generally for quasilinear differential equations of the second order in two variables. This is necessary because of the manifold requirements to be demanded from the theory of characteristics.
Covariant Noncommutative Field Theory
Estrada-Jimenez, S.; Garcia-Compean, H.; Obregon, O.; Ramirez, C.
2008-07-02
The covariant approach to noncommutative field and gauge theories is revisited. In the process the formalism is applied to field theories invariant under diffeomorphisms. Local differentiable forms are defined in this context. The lagrangian and hamiltonian formalism is consistently introduced.
General properties of nonsignaling theories
NASA Astrophysics Data System (ADS)
Masanes, Ll.; Acin, A.; Gisin, N.
2006-01-01
This article identifies a series of properties common to all theories that do not allow for superluminal signaling and predict the violation of Bell inequalities. Intrinsic randomness, uncertainty due to the incompatibility of two observables, monogamy of correlations, impossibility of perfect cloning, privacy of correlations, bounds in the shareability of some states; all these phenomena are solely a consequence of the no-signaling principle and nonlocality. In particular, it is shown that for any distribution, the properties of (i) nonlocal, (ii) no arbitrarily shareable, and (iii) positive secrecy content are equivalent.
Constructor theory of probability
2016-01-01
Unitary quantum theory, having no Born Rule, is non-probabilistic. Hence the notorious problem of reconciling it with the unpredictability and appearance of stochasticity in quantum measurements. Generalizing and improving upon the so-called ‘decision-theoretic approach’, I shall recast that problem in the recently proposed constructor theory of information—where quantum theory is represented as one of a class of superinformation theories, which are local, non-probabilistic theories conforming to certain constructor-theoretic conditions. I prove that the unpredictability of measurement outcomes (to which constructor theory gives an exact meaning) necessarily arises in superinformation theories. Then I explain how the appearance of stochasticity in (finitely many) repeated measurements can arise under superinformation theories. And I establish sufficient conditions for a superinformation theory to inform decisions (made under it) as if it were probabilistic, via a Deutsch–Wallace-type argument—thus defining a class of decision-supporting superinformation theories. This broadens the domain of applicability of that argument to cover constructor-theory compliant theories. In addition, in this version some of the argument's assumptions, previously construed as merely decision-theoretic, follow from physical properties expressed by constructor-theoretic principles. PMID:27616914
ERIC Educational Resources Information Center
Peim, Nick
2009-01-01
This paper seeks to re-examine Yrio Engestrom's activity theory as a technology of knowledge designed to enable positive transformations of specific practices. The paper focuses on a key paper where Engestrom defines the nature and present state of activity theory. Beginning with a brief account of the relations between activity theory and…
ERIC Educational Resources Information Center
Pais, Alexandre; Valero, Paola
2014-01-01
What is the place of social theory in mathematics education research, and what is it for? This special issue of "Educational Studies in Mathematics" offers insights on what could be the role of some sociological theories in a field that has historically privileged learning theories coming from psychology and mathematics as the main…
ERIC Educational Resources Information Center
Rajendran, Gnanathusharan; Mitchell, Peter
2007-01-01
This article considers three theories of autism: The Theory of Mind Deficit, Executive Dysfunction and the Weak Central Coherence accounts. It outlines each along with studies relevant to their emergence, their expansion, their limitations and their possible integration. Furthermore, consideration is given to any implication from the theories in…
Quantum Electrodynamics: Theory
Lincoln, Don
2016-03-30
The Standard Model of particle physics is composed of several theories that are added together. The most precise component theory is the theory of quantum electrodynamics or QED. In this video, Fermilab’s Dr. Don Lincoln explains how theoretical QED calculations can be done. This video links to other videos, giving the viewer a deep understanding of the process.
ERIC Educational Resources Information Center
Rudner, Lawrence M.
This paper describes and evaluates the use of decision theory as a tool for classifying examinees based on their item response patterns. Decision theory, developed by A. Wald (1947) and now widely used in engineering, agriculture, and computing, provides a simple model for the analysis of categorical data. Measurement decision theory requires only…
Quantum Electrodynamics: Theory
Lincoln, Don
2016-07-12
The Standard Model of particle physics is composed of several theories that are added together. The most precise component theory is the theory of quantum electrodynamics or QED. In this video, Fermilabâs Dr. Don Lincoln explains how theoretical QED calculations can be done. This video links to other videos, giving the viewer a deep understanding of the process.
Constructor theory of probability.
Marletto, Chiara
2016-08-01
Unitary quantum theory, having no Born Rule, is non-probabilistic. Hence the notorious problem of reconciling it with the unpredictability and appearance of stochasticity in quantum measurements. Generalizing and improving upon the so-called 'decision-theoretic approach', I shall recast that problem in the recently proposed constructor theory of information-where quantum theory is represented as one of a class of superinformation theories, which are local, non-probabilistic theories conforming to certain constructor-theoretic conditions. I prove that the unpredictability of measurement outcomes (to which constructor theory gives an exact meaning) necessarily arises in superinformation theories. Then I explain how the appearance of stochasticity in (finitely many) repeated measurements can arise under superinformation theories. And I establish sufficient conditions for a superinformation theory to inform decisions (made under it) as if it were probabilistic, via a Deutsch-Wallace-type argument-thus defining a class of decision-supporting superinformation theories. This broadens the domain of applicability of that argument to cover constructor-theory compliant theories. In addition, in this version some of the argument's assumptions, previously construed as merely decision-theoretic, follow from physical properties expressed by constructor-theoretic principles.
Reflections on Activity Theory
ERIC Educational Resources Information Center
Bakhurst, David
2009-01-01
It is sometimes suggested that activity theory represents the most important legacy of Soviet philosophy and psychology. But what exactly "is" activity theory? The canonical account in the West is given by Engestrom, who identifies three stages in the theory's development: from Vygotsky's insights, through Leontiev's articulation of the…
Understanding Second-Order Theory of Mind
2015-03-01
2.0 [ Artificial Intelligence ]: General—cognitive simula- tion; I.2.11 [ Artificial Intelligence ]: Distributed Artificial Intelligence — intelligent ...posit that that mechanism is simulation. Overall, robots with theory of mind are viewed as more natural and intelligent teammates to their human
La theorie autrement (Theory in Another Light).
ERIC Educational Resources Information Center
Bertocchini, Paola; Costanzo, Edwige
1985-01-01
Outlines a technique using articles from "Le Francais dans le Monde" to teach reading comprehension and theory simultaneously to teachers of French as a second language. Describes a program in Italy using this approach. (MSE)
Matching theory in natural human environments
McDowell, J. J.
1988-01-01
Matching theory is a mathematical account of behavior, many aspects of which have been confirmed in laboratory experiments with nonhuman and human subjects. The theory asserts that behavior is distributed across concurrently available response alternatives in the same proportion that reinforcement is distributed across those alternatives. The theory also asserts that behavior on a single response alternative is a function not only of reinforcement contingent on that behavior, but also of reinforcement contingent on other behaviors and of reinforcement delivered independently of behavior. These assertions constitute important advances in our understanding of the effects of reinforcement on behavior. Evidence from the applied literature suggests that matching theory holds not only in laboratory environments, but also in natural human environments. In addition, the theory has important therapeutic implications. For example, it suggests four new intervention strategies, and it can be used to improve treatment planning and management. Research on matching theory illustrates the progression from laboratory experimentation with nonhuman subjects to therapeutic applications in natural human environments. PMID:22478003
Tensor modes on the string theory landscape
NASA Astrophysics Data System (ADS)
Westphal, Alexander
2013-04-01
We attempt an estimate for the distribution of the tensor mode fraction r over the landscape of vacua in string theory. The dynamics of eternal inflation and quantum tunneling lead to a kind of democracy on the landscape, providing no bias towards large-field or small-field inflation regardless of the class of measure. The tensor mode fraction then follows the number frequency distributions of inflationary mechanisms of string theory over the landscape. We show that an estimate of the relative number frequencies for small-field vs large-field inflation, while unattainable on the whole landscape, may be within reach as a regional answer for warped Calabi-Yau flux compactifications of type IIB string theory.
Family systems theory, attachment theory, and culture.
Rothbaum, Fred; Rosen, Karen; Ujiie, Tatsuo; Uchida, Nobuko
2002-01-01
Family systems theory and attachment theory have important similarities and complementarities. Here we consider two areas in which the theories converge: (a) in family system theorists' description of an overly close, or "enmeshed," mother-child dyad, which attachment theorists conceptualize as the interaction of children's ambivalent attachment and mothers' preoccupied attachment; (b) in family system theorists' description of the "pursuer-distance cycle" of marital conflict, which attachment theorists conceptualize as the interaction of preoccupied and dismissive partners. We briefly review family systems theory evidence, and more extensively review attachment theory evidence, pertaining to these points of convergence. We also review cross-cultural research, which leads us to conclude that the dynamics described in both theories reflect, in part, Western ways of thinking and Western patterns of relatedness. Evidence from Japan suggests that extremely close ties between mother and child are perceived as adaptive, and are more common, and that children experience less adverse effects from such relationships than do children in the West. Moreover, in Japan there is less emphasis on the importance of the exclusive spousal relationship, and less need for the mother and father to find time alone to rekindle romantic, intimate feelings and to resolve conflicts by openly communicating their differences. Thus, the "maladaptive" pattern frequently cited by Western theorists of an extremely close mother-child relationship, an unromantic, conflictual marriage characterized by little verbal communication and a peripheral, distant father, may function very differently in other cultures. While we believe that both theories will be greatly enriched by their integration, we caution against the application of either theory outside the cultures in which they were developed.
A thermodynamic theory of dynamic fragmentation
Yew, Ching H.; Taylor, P.A.
1993-08-01
We present a theory of dynamic fragmentation of brittle materials based on thermodynamic arguments. We recover the expressions for average fragment size and number as originally derived by Grady. We extend the previous work by obtaining descriptions of fragment size distribution and compressibility change due to the fragmentation process. The size distribution is assumed to be proportional to the spectral power of the strain history and a sample distribution is presented for a fragmentation process corresponding to a constant rate strain history. The description of compressibility change should be useful in computational studies of fragmentation. These results should provide insight into the process of fragmentation of brittle materials from hypervelocity impact.
Application of Theodorsen's Theory to Propeller Design
NASA Technical Reports Server (NTRS)
Crigler, John L
1948-01-01
A theoretical analysis is presented for obtaining by use of Theodorsen's propeller theory the load distribution along a propeller radius to give the optimum propeller efficiency for any design condition.The efficiencies realized by designing for the optimum load distribution are given in graphs, and the optimum efficiency for any design condition may be read directly from the graph without any laborious calculations. Examples are included to illustrate the method of obtaining the optimum load distributions for both single-rotating and dual-rotating propellers.
Application of Theodorsen's theory to propeller design
NASA Technical Reports Server (NTRS)
Crigler, John L
1949-01-01
A theoretical analysis is presented for obtaining, by use of Theodorsen's propeller theory, the load distribution along a propeller radius to give the optimum propeller efficiency for any design condition. The efficiencies realized by designing for the optimum load distribution are given in graphs, and the optimum efficiency for any design condition may be read directly from the graph without any laborious calculations. Examples are included to illustrate the method of obtaining the optimum load distributions for both single-rotating and dual-rotating propellers.
Variational Transition State Theory
Truhlar, Donald G.
2016-09-29
This is the final report on a project involving the development and applications of variational transition state theory. This project involved the development of variational transition state theory for gas-phase reactions, including optimized multidimensional tunneling contributions and the application of this theory to gas-phase reactions with a special emphasis on developing reaction rate theory in directions that are important for applications to combustion. The development of variational transition state theory with optimized multidimensional tunneling as a useful computational tool for combustion kinetics involved eight objectives.
Levy, Florence
2007-11-01
The purpose of the present paper was to review psychological theories of autism, and to integrate these theories with neurobiological findings. Cognitive, theory of mind, language and coherence theories were identified, and briefly reviewed. Psychological theories were found not to account for the rigid/repetitive behaviours universally described in autistic subjects, and underlying neurobiological systems were identified. When the developing brain encounters constrained connectivity, it evolves an abnormal organization, the features of which may be best explained by a developmental failure of neural connectivity, where high local connectivity develops in tandem with low long-range connectivity, resulting in constricted repetitive behaviours.
Towards a Theory of Leadership Practice: A Distributed Perspective
ERIC Educational Resources Information Center
Spillane, James; Halverson, Richard; Diamond, John
2004-01-01
School-level conditions and school leadership, in particular, are key issues in efforts to change instruction. While new organizational structures and new leadership roles matter to instructional innovation, what seems most critical is how leadership practice is undertaken. Yet, the practice of school leadership has received limited attention in…
Representing and Testing Organizational Theories: A Holistic Construal.
ERIC Educational Resources Information Center
Bagozzi, Richard P.; Phillips, Lynn W.
1982-01-01
Tests the "holistic construal" method of validating constructs and testing organizational hypotheses, using examples from organizational theory and data on wholesale distribution companies. Holistic construal is meant to explicitly represent theoretical and empirical concepts, nonobservational hypotheses, and correspondence rules and…
Theory of Multiple Coulomb Scattering from Extended Nuclei
DOE R&D Accomplishments Database
Cooper, L. N.; Rainwater, J.
1954-08-01
Two independent methods are described for calculating the multiple scattering distribution for projected angle scattering resulting when very high energy charged particles traverse a thick scatterer. The results are compared with the theories of Moliere and Olbert.
The Challenges of Distributing Leadership in Irish Post-Primary Schools
ERIC Educational Resources Information Center
O'Donovan, Margaret
2015-01-01
This study explores the challenges and opportunities in relation to developing distributed leadership practice in Irish post-primary schools. It considers school leadership within the context of contemporary distributed leadership theory. Associated concepts such as distributed cognition and activity theory are used to frame the study. The study…
NASA Technical Reports Server (NTRS)
Owre, Sam; Shankar, Natarajan; Butler, Ricky W. (Technical Monitor)
2001-01-01
The purpose of this task was to provide a mechanism for theory interpretations in a prototype verification system (PVS) so that it is possible to demonstrate the consistency of a theory by exhibiting an interpretation that validates the axioms. The mechanization makes it possible to show that one collection of theories is correctly interpreted by another collection of theories under a user-specified interpretation for the uninterpreted types and constants. A theory instance is generated and imported, while the axiom instances are generated as proof obligations to ensure that the interpretation is valid. Interpretations can be used to show that an implementation is a correct refinement of a specification, that an axiomatically defined specification is consistent, or that a axiomatically defined specification captures its intended models. In addition, the theory parameter mechanism has been extended with a notion of theory as parameter so that a theory instance can be given as an actual parameter to an imported theory. Theory interpretations can thus be used to refine an abstract specification or to demonstrate the consistency of an axiomatic theory. In this report we describe the mechanism in detail. This extension is a part of PVS version 3.0, which will be publicly released in mid-2001.
[Introduction to grounded theory].
Wang, Shou-Yu; Windsor, Carol; Yates, Patsy
2012-02-01
Grounded theory, first developed by Glaser and Strauss in the 1960s, was introduced into nursing education as a distinct research methodology in the 1970s. The theory is grounded in a critique of the dominant contemporary approach to social inquiry, which imposed "enduring" theoretical propositions onto study data. Rather than starting from a set theoretical framework, grounded theory relies on researchers distinguishing meaningful constructs from generated data and then identifying an appropriate theory. Grounded theory is thus particularly useful in investigating complex issues and behaviours not previously addressed and concepts and relationships in particular populations or places that are still undeveloped or weakly connected. Grounded theory data analysis processes include open, axial and selective coding levels. The purpose of this article was to explore the grounded theory research process and provide an initial understanding of this methodology.
Angular Distributions of Synchrotron Radiation in the Nonrelativistic Approximation
NASA Astrophysics Data System (ADS)
Bagrov, V. G.; Loginov, A. S.
2017-03-01
The angular distribution functions of the polarized components of synchrotron radiation in the nonrelativistic approximation are investigated using methods of classical and quantum theory. Particles of zero spin (bosons) and spin 1/2 (electrons) are considered in the quantum theory. It is shown that in the first nonzero approximation the angular distribution functions, calculated by methods of classical and quantum theory, coincide identically. Quantum corrections to the angular distribution functions appear only in the subsequent approximation whereas the total radiated power contains quantum and spin corrections already in the first approximation.
Charge distribution over dust particles configured with size distribution in a complex plasma
NASA Astrophysics Data System (ADS)
Misra, Shikha; Mishra, Sanjay K.
2016-02-01
A theoretical kinetic model describing the distribution of charge on the dust particles configured with generalized Kappa size distribution in a complex plasma has been developed. The formulation is based on the manifestation of uniform potential theory with an analytical solution of the master differential equation for the probability density function of dust charge; the number and energy balance of the plasma constituents are utilized in writing the kinetic equations. A parametric study to determine the steady state plasma parameters and the charge distribution corresponding to a size distribution of dust grains in the complex plasma has been made; the numerical results are presented graphically. The charge distribution is seen sensitive to the population of small grains in the particle size distribution and thus in contrast to symmetrical distribution of charge around a mean value for uniform sized grains, the charge distribution in the present case peaks around lower charge.
Steps in the philosophy of quantum theory
NASA Astrophysics Data System (ADS)
Görnitz, Th.; Weizsäcker, C. F. V.
1. Interpretation. The Copenhagen Interpretation (CI) is a minimal semantics to quantum theory, expressing what we know at least. It can be extended into a universal Quantum Theory, applied to the observer as well as to the observed object. 2. A Universal Theory as a Philosophical Problem. A circular epistemology is proposed, consisting of nonhierarchical realism, empirism, apriorism and evolutionism, combined in a description of time: past. as discrete facts, future as continuous possibilities. 3. Quantum Logic and the Reconstruction of Quantum Theory. Non-distributive logic and Bell's theorem are discussed following Doebner and Lücke. Reconstruction is briefly described. 4. Further Philosophical Questions. Mind-body problem and holism are briefly discussed.
GravitoMagnetic Field in Tensor-Vector-Scalar Theory
Exirifard, Qasem
2013-04-01
We study the gravitomagnetism in the TeVeS theory. We compute the gravitomagnetic field that a slow moving mass distribution produces in its Newtonian regime. We report that the consistency between the TeVeS gravitomagnetic field and that predicted by the Einstein-Hilbert theory leads to a relation between the vector and scalar coupling constants of the theory. We translate the Lunar Laser Ranging measurement's data into a constraint on the deviation from this relation.
A Neural Theory of Visual Attention: Bridging Cognition and Neurophysiology
ERIC Educational Resources Information Center
Bundesen, Claus; Habekost, Thomas; Kyllingsbaek, Soren
2005-01-01
A neural theory of visual attention (NTVA) is presented. NTVA is a neural interpretation of C. Bundesen's (1990) theory of visual attention (TVA). In NTVA, visual processing capacity is distributed across stimuli by dynamic remapping of receptive fields of cortical cells such that more processing resources (cells) are devoted to behaviorally…
Learning Theory for Collaborative Large Shared Digital Spaces
ERIC Educational Resources Information Center
McGivern, Daniela; Morgan, Michael; Butler, Matthew
2012-01-01
This research applies Socio-Cultural theory and Distributed Cognition/Activity theory to conceptualize the design of collaborative learning activities in large shared digital spaces. The paper begins by providing a summary of previous work in the creation of a technology platform for large shared digital spaces. It then details how Socio-Cultural…
Modern Perspectives in Applied Mathematics: Theory and Numerics of PDEs
2015-04-13
SECURITY CLASSIFICATION OF: The International Conference on “Modern Perspectives in Applied Mathematics : Theory and Numerics of PDEs” took place April... mathematics , focusing on theoretical, computational and applied aspects of partial differential equations. The meeting brought together researchers from...Release; Distribution Unlimited Final Report: Modern Perspectives in Applied Mathematics : Theory and Numerics of PDEs The views, opinions and/or
Random distributed feedback fibre lasers
NASA Astrophysics Data System (ADS)
Turitsyn, Sergei K.; Babin, Sergey A.; Churkin, Dmitry V.; Vatnik, Ilya D.; Nikulin, Maxim; Podivilov, Evgenii V.
2014-09-01
The concept of random lasers exploiting multiple scattering of photons in an amplifying disordered medium in order to generate coherent light without a traditional laser resonator has attracted a great deal of attention in recent years. This research area lies at the interface of the fundamental theory of disordered systems and laser science. The idea was originally proposed in the context of astrophysics in the 1960s by V.S. Letokhov, who studied scattering with “negative absorption” of the interstellar molecular clouds. Research on random lasers has since developed into a mature experimental and theoretical field. A simple design of such lasers would be promising for potential applications. However, in traditional random lasers the properties of the output radiation are typically characterized by complex features in the spatial, spectral and time domains, making them less attractive than standard laser systems in terms of practical applications. Recently, an interesting and novel type of one-dimensional random laser that operates in a conventional telecommunication fibre without any pre-designed resonator mirrors-random distributed feedback fibre laser-was demonstrated. The positive feedback required for laser generation in random fibre lasers is provided by the Rayleigh scattering from the inhomogeneities of the refractive index that are naturally present in silica glass. In the proposed laser concept, the randomly backscattered light is amplified through the Raman effect, providing distributed gain over distances up to 100 km. Although an effective reflection due to the Rayleigh scattering is extremely small (˜0.1%), the lasing threshold may be exceeded when a sufficiently large distributed Raman gain is provided. Such a random distributed feedback fibre laser has a number of interesting and attractive features. The fibre waveguide geometry provides transverse confinement, and effectively one-dimensional random distributed feedback leads to the generation
Sprakel, Joris; Leermakers, Frans A M; Cohen Stuart, Martien A; Besseling, Nicolaas A M
2008-09-14
A comprehensive theory is proposed that combines classical nucleation and polymer brush theory to describe star-like polymer micelles. With a minimum of adjustable parameters, the model predicts properties such as critical micelle concentrations and micellar size distributions. The validity of the present theory is evidenced in direct comparison to experiments; this revealed that the proportionality constant in the Daoud-Cotton model is of the order of unity and that the star-limit is valid down to relatively short corona chains. Furthermore, we show that the predicted saddle points in the free energy correspond to those solutions that are accessible with self-consistent field methods for self-assembly.
Chen, Jiale; Gao, Zhe
2013-08-15
The second-order velocity distribution function was calculated from the second-order rf kinetic theory [Jaeger et al., Phys. Plasmas 7, 641 (2000)]. However, the nonresonant ponderomotive force in the radial direction derived from the theory is inconsistent with that from the fluid theory. The inconsistency arises from that the multiple-timescale-separation assumption fails when the second-order Vlasov equation is directly integrated along unperturbed particle orbits. A slowly ramped wave field including an adiabatic turn-on process is applied in the modified kinetic theory in this paper. Since this modification leads only to additional reactive/nonresonant response relevant with the secular resonant response from the previous kinetic theory, the correct nonresonant ponderomotive force can be obtained while all the resonant moments remain unchanged.
Supersymmetry and String Theory
NASA Astrophysics Data System (ADS)
Dine, Michael
2016-01-01
Preface to the first edition; Preface to the second edition; A note on choice of metric; Text website; Part I. Effective Field Theory: The Standard Model, Supersymmetry, Unification: 1. Before the Standard Model; 2. The Standard Model; 3. Phenomenology of the Standard Model; 4. The Standard Model as an effective field theory; 5. Anomalies, instantons and the strong CP problem; 6. Grand unification; 7. Magnetic monopoles and solitons; 8. Technicolor: a first attempt to explain hierarchies; Part II. Supersymmetry: 9. Supersymmetry; 10. A first look at supersymmetry breaking; 11. The Minimal Supersymmetric Standard Model; 12. Supersymmetric grand unification; 13. Supersymmetric dynamics; 14. Dynamical supersymmetry breaking; 15. Theories with more than four conserved supercharges; 16. More supersymmetric dynamics; 17. An introduction to general relativity; 18. Cosmology; 19. Astroparticle physics and inflation; Part III. String Theory: 20. Introduction; 21. The bosonic string; 22. The superstring; 23. The heterotic string; 24. Effective actions in ten dimensions; 25. Compactification of string theory I. Tori and orbifolds; 26. Compactification of string theory II. Calabi-Yau compactifications; 27. Dynamics of string theory at weak coupling; 28. Beyond weak coupling: non-perturbative string theory; 29. Large and warped extra dimensions; 30. The landscape: a challenge to the naturalness principle; 31. Coda: where are we headed?; Part IV. The Appendices: Appendix A. Two-component spinors; Appendix B. Goldstone's theorem and the pi mesons; Appendix C. Some practice with the path integral in field theory; Appendix D. The beta function in supersymmetric Yang-Mills theory; References; Index.
Characterizing maximally singular phase-space distributions
NASA Astrophysics Data System (ADS)
Sperling, J.
2016-07-01
Phase-space distributions are widely applied in quantum optics to access the nonclassical features of radiations fields. In particular, the inability to interpret the Glauber-Sudarshan distribution in terms of a classical probability density is the fundamental benchmark for quantum light. However, this phase-space distribution cannot be directly reconstructed for arbitrary states, because of its singular behavior. In this work, we perform a characterization of the Glauber-Sudarshan representation in terms of distribution theory. We address important features of such distributions: (i) the maximal degree of their singularities is studied, (ii) the ambiguity of representation is shown, and (iii) their dual space for nonclassicality tests is specified. In this view, we reconsider the methods for regularizing the Glauber-Sudarshan distribution for verifying its nonclassicality. This treatment is supported with comprehensive examples and counterexamples.
Spin quasi-distribution functions
NASA Astrophysics Data System (ADS)
Scully, M. O.; Wódkiewicz, K.
1994-01-01
Two-classes of phase-space spin quasi-distribution functions are introduced and discussed. The first class of these distributions is based on the delta function construction. It is shown that such a construction can be carried out for an arbitrary spin s and an arbitrary ordering of the spin operators. The second class of the spin distributions is constructed with the help of the spin coherent states. The connection of the spin coherent states to the Stratonovich formalism is established and discussed. It is shown that the c-number phase-space description of quantum fluctuations provides a simple statistical picture of quantum fluctuations of spinoperators in terms of random directions on a unit sphere. For quantum states of the spin system the statistics of these random orientations is given by non-positive spin quasi-distribution functions. It is shown that the application of these spin quasi-distribution functions to the Einstein-Podolsky-Rosen correlations provide an insight into the quantum theory of measurement.
Naylor, Ron
2007-03-01
The aim of Galileo's tidal theory was to show that the tides were produced entirely by the earth's motion and thereby to demonstrate the physical truth of Copernicanism. However, in the Dialogue Concerning the Two Chief World Systems Galileo did not explain some of the most significant aspects of the theory completely. As a consequence, the way the theory works has long been disputed. Though there exist a number of interpretations in the literature, the most widely accepted are based on ideas that are not explicitly articulated by Galileo in the Dialogue. This essay attempts to understand the way the theory functions in terms of Galilean physics. It is an interpretation of the theory based solely on Galileo's arguments--and one that reveals it to have had some unrecognized consequences. This interpretation indicates that Galileo's theory would not have worked in the manner he described in the Dialogue.
Children's theories of motivation.
Gurland, Suzanne T; Glowacky, Victoria C
2011-09-01
To investigate children's theories of motivation, we asked 166 children (8-12 years of age) to rate the effect of various motivational strategies on task interest, over the short and long terms, in activities described as appealing or unappealing. Children viewed the rewards strategy as resulting in greatest interest except when implemented over the long term for appealing activities. Individual difference analyses revealed that some children held operant theories of motivation, in which rewards were central, and others held hybrid theories, in which rewards were key, but some allowance was made for interest to be self-sustaining in the absence of inducements. Children's theories predicted their academic self-regulation. Their theories are discussed relative to an expert theory of motivation.
Distributions of polynomials on multidimensional and infinite-dimensional spaces with measures
NASA Astrophysics Data System (ADS)
Bogachev, V. I.
2016-08-01
This paper provides a survey of recent investigations connected with distributions of polynomials on multi- and infinite-dimensional spaces with measures. The most important results on estimates (independent of the number of variables) for distribution functions and integral norms and also on convergence of the distributions of polynomials in variation and in the Kantorovich metric are presented. Interesting open problems in this area at the junction of the theory of functions, probability theory, and measure theory are discussed. Bibliography: 131 titles.
Theory of fermion condensation as an analog of the liquid-drop theory of atomic nuclei
Khodel, V. A.
2015-01-15
We discuss problems of theory of systems with a fermion condensate or, in different words, systems with flat bands pinned to the Fermi surface, employing the duality of the momentum distribution n(p) and the density distribution ρ(r). We propose that the Lifshitz topological phase transition associated with the formation of additional pockets of the Fermi surface is the precursor of fermion condensation.
Automated Lattice Perturbation Theory
Monahan, Christopher
2014-11-01
I review recent developments in automated lattice perturbation theory. Starting with an overview of lattice perturbation theory, I focus on the three automation packages currently "on the market": HiPPy/HPsrc, Pastor and PhySyCAl. I highlight some recent applications of these methods, particularly in B physics. In the final section I briefly discuss the related, but distinct, approach of numerical stochastic perturbation theory.
NASA Technical Reports Server (NTRS)
Ostwald, Wolfgang
1988-01-01
A brief summary of the fundamentals of the Linear theory of flotation is given. The theory by no means contradicts the previous Laminar theory or even the thermodynamics (Wark-Siedler), rather it is a refinement of the known Hardy-Langmuir-Harkin conceptions for the case when there are not two phases and phase boundaries, but rather three phases and corresponding phase boundary edges. The appearance of such three-phase boundaries (ore, water, air) is characteristic for modern flotation methods.
Theory Modeling and Simulation
Shlachter, Jack
2012-08-23
Los Alamos has a long history in theory, modeling and simulation. We focus on multidisciplinary teams that tackle complex problems. Theory, modeling and simulation are tools to solve problems just like an NMR spectrometer, a gas chromatograph or an electron microscope. Problems should be used to define the theoretical tools needed and not the other way around. Best results occur when theory and experiments are working together in a team.
ERIC Educational Resources Information Center
Costley, Kevin C.
2006-01-01
University professors teaching pre-service teachers base much of their philosophies on theories. Students often ask "Why do we have theories?" "What is the purpose of theories?" "If we like a theory, do we have to use all of the theory?" The most frequent controversial issue is how to use a particular theory in a practical way. In the quest for…
Between Theory and Observations
NASA Astrophysics Data System (ADS)
Wepster, Steven
Three great mathematicians dominate the history of lunar theory in the middle of the eighteenth century: Leonhard Euler, Alexis Clairaut, and Jean le Rond d’Alembert. Each of them made a lasting contribution to the theory of celestial mechanics and their results had a broader impact than on lunar theory alone. To name but a few examples, Euler codified the trigonometric functions and pioneered the method of variation of orbital constants; Clairaut solved the arduous problem of the motion of the lunar apogee, thereby dealing a decisive blow to the sceptics of Newton’s law of gravitation; and d’Alembert worked out an accurate theory of precession and nutation.
1976-05-01
A~ —~ on 022 CAMBRIDGE UNIV (ENGLAND) CAVEND ISH LAB —. FIG 20/12 —“1THEORY OF SOLID SURFACES .(U) MAY 76 ~J C INKS ON, P W ANDERSON AF AFOSR...t_ ~ - ~ - ~~~~~ ~~ ~~~~~~~~~~~~~~~~~~~ Grant Number AFOSR 73—2le~9 ~ Theory of Solid Surfaces J.C. INKSON and P.W. ANDERSON Cavendish Laboratory... solid state techniques to the theory of nucleii and neutron stars . On surfaces an important : ew development is described in the theory of catalysis
NASA Astrophysics Data System (ADS)
Chen, Jing-Yuan; Son, Dam Thanh
2017-02-01
We develop an extension of the Landau Fermi liquid theory to systems of interacting fermions with non-trivial Berry curvature. We propose a kinetic equation and a constitutive relation for the electromagnetic current that together encode the linear response of such systems to external electromagnetic perturbations, to leading and next-to-leading orders in the expansion over the frequency and wave number of the perturbations. We analyze the Feynman diagrams in a large class of interacting quantum field theories and show that, after summing up all orders in perturbation theory, the current-current correlator exactly matches with the result obtained from the kinetic theory.
Lincoln, Don
2016-07-12
The Big Bang is the name of the most respected theory of the creation of the universe. Basically, the theory says that the universe was once smaller and denser and has been expending for eons. One common misconception is that the Big Bang theory says something about the instant that set the expansion into motion, however this isnât true. In this video, Fermilabâs Dr. Don Lincoln tells about the Big Bang theory and sketches some speculative ideas about what caused the universe to come into existence.
NASA Technical Reports Server (NTRS)
Baird, J. K.
1986-01-01
The Ostwald-ripening theory is deduced and discussed starting from the fundamental principles such as Ising model concept, Mayer cluster expansion, Langer condensation point theory, Ginzburg-Landau free energy, Stillinger cutoff-pair potential, LSW-theory and MLSW-theory. Mathematical intricacies are reduced to an understanding version. Comparison of selected works, from 1949 to 1984, on solution of diffusion equation with and without sink/sources term(s) is presented. Kahlweit's 1980 work and Marqusee-Ross' 1954 work are more emphasized. Odijk and Lekkerkerker's 1985 work on rodlike macromolecules is introduced in order to simulate interested investigators.
Lincoln, Don
2014-09-30
The Big Bang is the name of the most respected theory of the creation of the universe. Basically, the theory says that the universe was once smaller and denser and has been expending for eons. One common misconception is that the Big Bang theory says something about the instant that set the expansion into motion, however this isn’t true. In this video, Fermilab’s Dr. Don Lincoln tells about the Big Bang theory and sketches some speculative ideas about what caused the universe to come into existence.
Distributive Education. Physical Distribution. Instructor's Curriculum.
ERIC Educational Resources Information Center
Missouri Univ., Columbia. Instructional Materials Lab.
This distributive education performance-based instructional unit is designed to help students understand the system of physical distribution and to act as an aid to guiding students in preparing for future careers in the transportation industry dealing with the retail, wholesale, and service occupations. (Physical distribution involves the moving…
On the asymptotic distribution of block-modified random matrices
Arizmendi, Octavio; Nechita, Ion; Vargas, Carlos
2016-01-15
We study random matrices acting on tensor product spaces which have been transformed by a linear block operation. Using operator-valued free probability theory, under some mild assumptions on the linear map acting on the blocks, we compute the asymptotic eigenvalue distribution of the modified matrices in terms of the initial asymptotic distribution. Moreover, using recent results on operator-valued subordination, we present an algorithm that computes, numerically but in full generality, the limiting eigenvalue distribution of the modified matrices. Our analytical results cover many cases of interest in quantum information theory: we unify some known results and we obtain new distributions and various generalizations.
Distribution effectiveness for space radiation dosimetry
NASA Technical Reports Server (NTRS)
Wilson, J. W.
1975-01-01
A simplified risk basis and a theory of hematological response are presented and applied to the problem of dosimetry in the manned space program. Unlike previous studies, the current work incorporates radiation exposure distribution effects into its definition of dose equivalent. The fractional cell lethality model for prediction of hematological response is integral in the analysis.
The Distribution of Solubilized Molecules among Micelles.
ERIC Educational Resources Information Center
Miller, Dennis J.
1978-01-01
Conflicting views have been put forward on the derivation of the distribution of solubilized molecules among micelles. This stems from failure to consider the arrangement of the solubilized molecules in the micelles. In the treatment presented enthalpy effects are ignored as they are not amenable to a simple general theory. (Author/BB)
Asymptotic Distributions for Tests of Combined Significance.
ERIC Educational Resources Information Center
Becker, Betsy Jane
This paper discusses distribution theory and power computations for four common "tests of combined significance." These tests are calculated using one-sided sample probabilities or p values from independent studies (or hypothesis tests), and provide an overall significance level for the series of results. Noncentral asymptotic sampling…
Generalized Parton Distributions: Visions, Basics, and Realities
NASA Astrophysics Data System (ADS)
Müller, D.
2014-06-01
An introductory to generalized parton distributions (GDPs) is given which emphasizes their spectral property and its uses as well as the equivalence of various GDP representations. Furthermore, the status of the theory and phenomenology of hard exclusive processes is shortly reviewed.
Object Management in Local Distributed Systems
1985-11-01
Theory, Vol. 2, Jack Minker et a.l. editors, Plenum Press, New York, IQ84. / A3/ Gottlob , G., P. Paolini, and R. Zicari, "Properties and Update Semantics...February 1980. /D3/ Enslow, P., "What is a ’distributed’ data processing system?" IEEE Computer, 11, 1, January 1978. /D4/ Gottlob , G. and R. Zicari
A DISTRIBUTION-THEORETICAL APPROACH TO CERTAIN LEBESGUE AND SOBOLEV SPACES.
FUNCTIONAL ANALYSIS, * DISTRIBUTION THEORY ), PARTIAL DIFFERENTIAL EQUATIONS, OPERATORS(MATHEMATICS), FOURIER ANALYSIS, HILBERT SPACE, INTEGRAL TRANSFORMS, NUMERICAL INTEGRATION, TOPOLOGY, SERIES(MATHEMATICS), THEOREMS
A Theory of Imperfection: An Imperfect Theory?
ERIC Educational Resources Information Center
Piel, Ellen R.
1979-01-01
Problems faced by counselor education programs is that of reconciling the split between the traditional academic emphasis on teaching and research and practical experience and personal growth. Contends counselors' failure to recognize the value of theories in counseling may pose some problems for our profession as a whole. (Author)
Trubitsyn, A G
2012-01-01
In attempts to develop a means of life prolongation the humankind has created more than three hundred theories of the aging; each of them offers the original cause of aging. However, none of them has given practical result by now. The majority of the theories have now only historical interest. There are several different theories that are mainly under consideration currently. They are based on reliable, proven evidence: the free radical theory, the protein error theory, the replicative senescence theory, the theory of reparation weakening, the immunological theory, several versions of neuroendocrinal theories, and programmed aging theory. The theory presented here is based on conception that the life as the phenomenon represents many of the interconnected physical and chemical processes propelled by energy of the mitochondrial bioenergetical machine. Gradual degradation of all vital processes is caused by the programmed decrease in level of bioenergetics. This theory unites all existing theories of aging constructed on authentic facts: it is shown, that such fundamental phenomena accompanying aging process as the increase in level of reactive oxygen species (ROS), the decrease in the general level of protein synthesis, the limitation of cellular dividing (Haiflick limit), decrease in efficiency of reparation mechanisms are caused by bioenergetics attenuation. Each of these phenomena in turn generates a number of harmful secondary processes. Any of the theories bases on one of these destructive phenomena or their combination. Hence, each of them describes one of sides of process of the aging initially caused by programmed decrease of level of bioenergetics. This united theory gives the chance to understand the nature of aging clock and explains a phenomenon of increase in longevity at the condition of food restriction. Failures of attempts to develop means from aging are explained by that the manipulations with the separate secondary phenomena of attenuation of
Linear phase distribution of acoustical vortices
Gao, Lu; Zheng, Haixiang; Ma, Qingyu; Tu, Juan; Zhang, Dong
2014-07-14
Linear phase distribution of phase-coded acoustical vortices was theoretically investigated based on the radiation theory of point source, and then confirmed by experimental measurements. With the proposed criterion of positive phase slope, the possibility of constructing linear circular phase distributions is demonstrated to be determined by source parameters. Improved phase linearity can be achieved at larger source number, lower frequency, smaller vortex radius, and/or longer axial distance. Good agreements are observed between numerical simulations and measurement results for circular phase distributions. The favorable results confirm the feasibility of precise phase control for acoustical vortices and suggest potential applications in particle manipulation.
Deformations of the Tracy-Widom distribution.
Bohigas, O; de Carvalho, J X; Pato, M P
2009-03-01
In random matrix theory, the Tracy-Widom (TW) distribution describes the behavior of the largest eigenvalue. We consider here two models in which TW undergoes transformations. In the first one disorder is introduced in the Gaussian ensembles by superimposing an external source of randomness. A competition between TW and a normal (Gaussian) distribution results, depending on the spreading of the disorder. The second model consists of removing at random a fraction of (correlated) eigenvalues of a random matrix. The usual formalism of Fredholm determinants extends naturally. A continuous transition from TW to the Weilbull distribution, characteristic of extreme values of an uncorrelated sequence, is obtained.
Diffusion in the special theory of relativity.
Herrmann, Joachim
2009-11-01
The Markovian diffusion theory is generalized within the framework of the special theory of relativity. Since the velocity space in relativity is a hyperboloid, the mathematical stochastic calculus on Riemanian manifolds can be applied but adopted here to the velocity space. A generalized Langevin equation in the fiber space of position, velocity, and orthonormal velocity frames is defined from which the generalized relativistic Kramers equation in the phase space in external force fields is derived. The obtained diffusion equation is invariant under Lorentz transformations and its stationary solution is given by the Jüttner distribution. Besides, a nonstationary analytical solution is derived for the example of force-free relativistic diffusion.
Asymptotic Theory for Nonparametric Confidence Intervals.
1982-07-01
distributions. Ann. Math Statist. 14, 56-62. 24. ROY, S.N. and POTTHOFF, R.F. (1958). Confidence bounds on vector analogues of the "ratio of the mean" and...fl c,~_________ 14L TITLE feed &MV) S. TYPE or REPORT a PeftOo COVx:REC Asympeocic Theory for Nonaparuetric Technical Report Confidence Intevals 6...S..C-0S78 UNCLASSIFIED TŗU *uuuuumuuumhhhhmhhhm_4 ASYMPTOTIC THEORY FOR NONPARAMETRIC CONFIDENCE INTERVALS by Peter W. Glynn TECHNICAL REPORT NO. 63
H-Infinity-Optimal Control for Distributed Parameter Systems
1991-02-28
F. Callier and C.A. Desoer , "An Algebra of Transfer Functions for Distributed Linear Time-Invariant Systems," IEEE Trans. Circuits Syst., Sept. 1978...neeuey and -f by blog* nu"bM) This report describes progress in the development and application of H-infinity-optimal control theory to distributed...parameter systems. This research is intended to develop both theory and algorithms capable of providing realistic control systems for physical plants which
Universality and string theory
NASA Astrophysics Data System (ADS)
Bachlechner, Thomas Christian
The first run at the Large Hadron Collider has deeply challenged conventional notions of naturalness, and CMB polarization experiments are about to open a new window to early universe cosmology. As a compelling candidate for the ultraviolet completion of the standard model, string theory provides a prime opportunity to study both early universe cosmology and particle physics. However, relating low energy observations to ultraviolet physics requires knowledge of the metastable states of string theory through the study of vacua. While it is difficult to directly obtain infrared data from explicit string theory constructions, string theory imposes constraints on low energy physics. The study of ensembles of low energy theories consistent with ultra-violet constraints provides insight on generic features we might expect to occur in string compactifications. In this thesis we present a statistical treatment of vacuum stability and vacuum properties in the context of random supergravity theories motivated by string theory. Early universe cosmology provides another avenue to high energy physics. From the low energy perspective large field inflation is typically considered highly unnatural: the scale relevant for the diameter of flat regions in moduli space is sub-Planckian in regions of perturbative control. To approach this problem, we consider generic Calabi-Yau compactifications of string theory and find that super-Planckian diameters of axion fundamental domains in fact arise generically. We further demonstrate that such super-Planckian flat regions are plausibly consistent with theWeak Gravity Conjecture.
NASA Astrophysics Data System (ADS)
Livens, G. H.
2016-10-01
Preface; 1. The electric field; 2. Dielectric theory; 3. Electric currents; 4. The magnetic field; 5. The dynamics of the magnetic field; 6. Maxwell's electromagnetic theory; 7. Electromagnetic oscillations and waves; 8. The electrodynamics of moving media; Appendix 1. On the mechanism of magnetic induction; Appendix 2. On the mechanism of metallic conduction; Index.
ERIC Educational Resources Information Center
Minter, Robert L.
2011-01-01
This article addresses the myriad of pedagogical and andragogical issues facing university educators in the student learning process. It briefly explores the proliferation of learning theories in an attempt to develop awareness among faculty who teach at the university/college levels that not all theories of learning apply to the adult learner. In…
ERIC Educational Resources Information Center
Shor, Mikhael
2003-01-01
States making game theory relevant and accessible to students is challenging. Describes the primary goal of GameTheory.net is to provide interactive teaching tools. Indicates the site strives to unite educators from economics, political and computer science, and ecology by providing a repository of lecture notes and tests for courses using…
History, Theory, and Education
ERIC Educational Resources Information Center
Rury, John L.
2011-01-01
In this article, the author discusses the question of theory as it may pertain to the history of education, with particular attention to the United States. Historians, like everyone else, have little choice regarding the use of theory; to one extent or another they must. The question is how much and to what end. The author aims to consider the…
Evaluating Conceptual Metaphor Theory
ERIC Educational Resources Information Center
Gibbs, Raymond W., Jr.
2011-01-01
A major revolution in the study of metaphor occurred 30 years ago with the introduction of "conceptual metaphor theory" (CMT). Unlike previous theories of metaphor and metaphorical meaning, CMT proposed that metaphor is not just an aspect of language, but a fundamental part of human thought. Indeed, most metaphorical language arises from…
NASA Astrophysics Data System (ADS)
Maldacena, Juan Martín
D-Branes on Calabi-Yau manifolds / Paul S. Aspinwall -- Lectures on AdS/CFT / Juan M. Maldacena -- Tachyon dynamics in open string theory / Ashoke Sen -- TASI/PITP/ISS lectures on moduli and microphysics / Eva Silverstein -- The duality cascade / Matthew J. Strassler -- Perturbative computations in string field theory / Washington Taylor -- Student seminars -- Student participants -- Lecturers, directors, and local organizing committee.
1981-03-31
measured and appear to be comparable to those predicted by the Vlasov-fluid theory of Seylerl and the finite Larmor radius theory of Freidberg and...C.E. Seyler, "Vlasov-Fluid Stability of a Rigidly Rotating Theta Pinch," Phys. Fluids 22, 2324, (1979). 2. J.P. Freidberg , L.D. Pearlstein
NASA Technical Reports Server (NTRS)
Iesan, D.
1980-01-01
The development of the theory of thermoelasticity, which examines the interactions between the deformation of elastic media and the thermal field, is traced and the fundamental problems of the theory are presented. Results of recent studies on the subject are presented. Emphasis is primarily on media with generalized anisotropy, or isotropy media. Thermomechanical problems and mathematical formulations and resolutions are included.
ERIC Educational Resources Information Center
Roller, Duane H. D.
1981-01-01
Focusing on history of physics, which began about 600 B.C. with the Ionian Greeks and reaching full development within three centuries, suggests that the creation of the concept of the atom is understandable within the context of Greek physical theory; so is the rejection of the atomic theory by the Greek physicists. (Author/SK)
ERIC Educational Resources Information Center
Mislevy, Robert J.
Educational test theory consists of statistical and methodological tools to support inferences about examinees' knowledge, skills, and accomplishments. The evolution of test theory has been shaped by the nature of users' inferences which, until recently, have been framed almost exclusively in terms of trait and behavioral psychology. Progress in…
NASA Astrophysics Data System (ADS)
Zeh, H. D.
1999-04-01
This is a brief reply to S. Goldstein's article "Quantum theory without observers" in Physics Today. It is pointed out that Bohm's pilot wave theory is successful only because it keeps Schrödinger's (exact) wave mechanics unchanged, while the rest of it is observationally meaningless and solely based on classical prejudice.
French Theory's American Adventures
ERIC Educational Resources Information Center
Cusset, Francois
2008-01-01
In this article, the author discusses how it is simply too late to be still speaking about French theory and its role in the intellectual life of the United States today. It seems to many observers that the gap between real-life politics and theory's guerrillas is much too wide already, after 30 years of academic fever, for the two worlds to even…
Towards Extended Vantage Theory
ERIC Educational Resources Information Center
Glaz, Adam
2010-01-01
The applicability of Vantage Theory (VT), a model of (colour) categorization, to linguistic data largely depends on the modifications and adaptations of the model for the purpose. An attempt to do so proposed here, called Extended Vantage Theory (EVT), slightly reformulates the VT conception of vantage by capitalizing on some of the entailments of…
ERIC Educational Resources Information Center
Jaeger, Audrey J.; Dunstan, Stephany; Thornton, Courtney; Rockenbach, Alyssa B.; Gayles, Joy G.; Haley, Karen J.
2013-01-01
When making decisions that impact student learning, college educators often consider previous experiences, precedent, common sense, and advice from colleagues. But how often do they consider theory? At a recent state-level educators' meeting, the authors of this article asked 50 student affairs educators about the use of theory in their practice.…
Catterall, Simon; Hubisz, Jay; Balachandran, Aiyalam; Schechter, Joe
2013-01-05
This final report describes the activities of the high energy theory group at Syracuse University for the period 1 January 2010 through April 30 2013. The research conducted by the group includes lattice gauge theory, non-commutative geometry, phenomenology and mathematical physics.
ERIC Educational Resources Information Center
Mayer, William V.
In this paper the author examines the question of whether evolution is a theory or a dogma. He refutes the contention that there is a monolithic scientific conspiracy to present evolution as dogma and suggests that his own presentation might be more appropriately entitled "Creationism: Theory or Dogma." (PEB)
Theory and Motivational Psychology.
ERIC Educational Resources Information Center
Atkinson, John W.
Motivational psychology and test theory are compared in this discussion, which focuses on distinguishing the effects of motivation and of ability on test performance and educational achievement. Recent theory in achievement motivation considers the motivational significance of future goals as they affect present activities that are instrumental in…
ERIC Educational Resources Information Center
Peller, Lili E.
1996-01-01
Discusses several theories of play advanced before the development of psychoanalysis, including the theories of surplus energy, recreation, and practice. Examines the psychoanalytical view advanced by Freud and others, which focuses on the emotional release of play and its role in discovery and learning. (MDM)
ERIC Educational Resources Information Center
Rexhepi, Jevdet; Torres, Carlos Alberto
2011-01-01
This paper discusses Critical Theory, a model of theorizing in the field of the political sociology of education. We argue for a "reimagined" Critical Theory to herald an empowering, liberatory education that fosters curiosity and critical thinking, and a means for successful bottom-up, top-down political engagement. We present arguments…
Organization Theory as Ideology.
ERIC Educational Resources Information Center
Greenfield, Thomas B.
The theory that organizations are ideological inventions of the human mind is discussed. Organizational science is described as an ideology which is based upon social concepts and experiences. The main justification for organizational theory is that it attempts to answer why we behave as we do in social organizations. Ways in which ideas and…
Administrative Theory in Transition.
ERIC Educational Resources Information Center
Griffiths, Daniel E.
This monograph analyzes transition in educational administrative theory. A brief introductory section describes the theoretical movement, the substance and repercussions of Thomas Greenfield's critique of educational administrative theory in 1974, and emerging qualitative approaches. Seven readings, all written by the volume's author, view…
Einstein's Theory Fights off Challengers
NASA Astrophysics Data System (ADS)
2010-04-01
Two new and independent studies have put Einstein's General Theory of Relativity to the test like never before. These results, made using NASA's Chandra X-ray Observatory, show Einstein's theory is still the best game in town. Each team of scientists took advantage of extensive Chandra observations of galaxy clusters, the largest objects in the Universe bound together by gravity. One result undercuts a rival gravity model to General Relativity, while the other shows that Einstein's theory works over a vast range of times and distances across the cosmos. The first finding significantly weakens a competitor to General Relativity known as "f(R) gravity". "If General Relativity were the heavyweight boxing champion, this other theory was hoping to be the upstart contender," said Fabian Schmidt of the California Institute of Technology in Pasadena, who led the study. "Our work shows that the chances of its upsetting the champ are very slim." In recent years, physicists have turned their attention to competing theories to General Relativity as a possible explanation for the accelerated expansion of the universe. Currently, the most popular explanation for the acceleration is the so-called cosmological constant, which can be understood as energy that exists in empty space. This energy is referred to as dark energy to emphasize that it cannot be directly detected. In the f(R) theory, the cosmic acceleration comes not from an exotic form of energy but from a modification of the gravitational force. The modified force also affects the rate at which small enhancements of matter can grow over the eons to become massive clusters of galaxies, opening up the possibility of a sensitive test of the theory. Schmidt and colleagues used mass estimates of 49 galaxy clusters in the local universe from Chandra observations, and compared them with theoretical model predictions and studies of supernovas, the cosmic microwave background, and the large-scale distribution of galaxies. They
Evolutionary model of the personal income distribution
NASA Astrophysics Data System (ADS)
Kaldasch, Joachim
2012-11-01
The aim of this work is to develop a qualitative picture of the personal income distribution. Treating an economy as a self-organized system the key idea of the model is that the income distribution contains competitive and non-competitive contributions. The presented model distinguishes between three main income classes. 1. Capital income from private firms is shown to be the result of an evolutionary competition between products. A direct consequence of this competition is Gibrat’s law suggesting a lognormal income distribution for small private firms. Taking into account an additional preferential attachment mechanism for large private firms the income distribution is supplemented by a power law (Pareto) tail. 2. Due to the division of labor a diversified labor market is seen as a non-competitive market. In this case wage income exhibits an exponential distribution. 3. Also included is income from a social insurance system. It can be approximated by a Gaussian peak. A consequence of this theory is that for short time intervals a fixed ratio of total labor (total capital) to net income exists (Cobb-Douglas relation). A comparison with empirical high resolution income data confirms this pattern of the total income distribution. The theory suggests that competition is the ultimate origin of the uneven income distribution.
Jackendoff, Ray
2017-03-01
Formal theories of mental representation have receded from the importance they had in the early days of cognitive science. I argue that such theories are crucial in any mental domain, not just for their own sake, but to guide experimental inquiry, as well as to integrate the domain into the mind as a whole. To illustrate the criteria of adequacy for theories of mental representation, I compare two theoretical approaches to language: classical generative grammar (Chomsky, 1965, 1981, 1995) and the parallel architecture (Jackendoff, 1997, 2002). The grounds for comparison include (a) the internal coherence of the theory across phonology, syntax, and semantics; (b) the relation of language to other mental faculties; (c) the relationship between grammar and lexicon; (d) relevance to theories of language processing; and (e) the possibility of languages with little or no syntax.
NASA Astrophysics Data System (ADS)
Wagner, Richard P.; Norman, M. L.
2006-12-01
A working example of a Basic SkyNode serving theoretical data will be presented. The data is taken from the Simulated Cluster Archive (a set of simulated galaxy clusters, where each cluster was computed using four different physics models). The Theory SkyNode tables contain columns of both computational and observational interest. Examples will be shown of using this theoretical data for comparison to data taken from observational SkyNodes, and vice versa. The relative ease of setting up the Theory SkyNode is of import, as it represents a clear way to present tabular theory data to the Virtual Observatory. Also, the Theory SkyNode provides a prototype for additional "theory catalogs", which wil be created from other simulations. This work is supported by the University of California Office of the President via UCDRD-LLNL award "Scientific Data Management". Travel funding was provided by the US NVO Summer School.
ERIC Educational Resources Information Center
Faita, Daniel
1977-01-01
A sketch of the development of functionalism in relation to other linguistic theories and a brief analysis of the present state of the research. Topics covered are: form versus function; the impasse between distributional and transformational grammar; and transformational grammar according to Harris. (Text is in French.) (AMH)
Stochastic game theory: For playing games, not just for doing theory
Goeree, Jacob K.; Holt, Charles A.
1999-01-01
Recent theoretical advances have dramatically increased the relevance of game theory for predicting human behavior in interactive situations. By relaxing the classical assumptions of perfect rationality and perfect foresight, we obtain much improved explanations of initial decisions, dynamic patterns of learning and adjustment, and equilibrium steady-state distributions. PMID:10485862
No signaling and quantum key distribution.
Barrett, Jonathan; Hardy, Lucien; Kent, Adrian
2005-07-01
Standard quantum key distribution protocols are provably secure against eavesdropping attacks, if quantum theory is correct. It is theoretically interesting to know if we need to assume the validity of quantum theory to prove the security of quantum key distribution, or whether its security can be based on other physical principles. The question would also be of practical interest if quantum mechanics were ever to fail in some regime, because a scientifically and technologically advanced eavesdropper could perhaps use postquantum physics to extract information from quantum communications without necessarily causing the quantum state disturbances on which existing security proofs rely. Here we describe a key distribution scheme provably secure against general attacks by a postquantum eavesdropper limited only by the impossibility of superluminal signaling. Its security stems from violation of a Bell inequality.
Introduction to string theory and conformal field theory
Belavin, A. A. Tarnopolsky, G. M.
2010-05-15
A concise survey of noncritical string theory and two-dimensional conformal field theory is presented. A detailed derivation of a conformal anomaly and the definition and general properties of conformal field theory are given. Minimal string theory, which is a special version of the theory, is considered. Expressions for the string susceptibility and gravitational dimensions are derived.
Theory of Multiple Intelligences: Is It a Scientific Theory?
ERIC Educational Resources Information Center
Chen, Jie-Qi
2004-01-01
This essay discusses the status of multiple intelligences (MI) theory as a scientific theory by addressing three issues: the empirical evidence Gardner used to establish MI theory, the methodology he employed to validate MI theory, and the purpose or function of MI theory.
NASA Astrophysics Data System (ADS)
Bastin, Ted
2009-07-01
List of participants; Preface; Part I. Introduction: 1. The function of the colloquium - editorial; 2. The conceptual problem of quantum theory from the experimentalist's point of view O. R. Frisch; Part II. Niels Bohr and Complementarity: The Place of the Classical Language: 3. The Copenhagen interpretation C. F. von Weizsäcker; 4. On Bohr's views concerning the quantum theory D. Bohm; Part III. The Measurement Problem: 5. Quantal observation in statistical interpretation H. J. Groenewold; 6. Macroscopic physics, quantum mechanics and quantum theory of measurement G. M. Prosperi; 7. Comment on the Daneri-Loinger-Prosperi quantum theory of measurement Jeffrey Bub; 8. The phenomenology of observation and explanation in quantum theory J. H. M. Whiteman; 9. Measurement theory and complex systems M. A. Garstens; Part IV. New Directions within Quantum Theory: What does the Quantum Theoretical Formalism Really Tell Us?: 10. On the role of hidden variables in the fundamental structure of physics D. Bohm; 11. Beyond what? Discussion: space-time order within existing quantum theory C. W. Kilmister; 12. Definability and measurability in quantum theory Yakir Aharonov and Aage Petersen; 13. The bootstrap idea and the foundations of quantum theory Geoffrey F. Chew; Part V. A Fresh Start?: 14. Angular momentum: an approach to combinatorial space-time Roger Penrose; 15. A note on discreteness, phase space and cohomology theory B. J. Hiley; 16. Cohomology of observations R. H. Atkin; 17. The origin of half-integral spin in a discrete physical space Ted Bastin; Part VI. Philosophical Papers: 18. The unity of physics C. F. von Weizsäcker; 19. A philosophical obstacle to the rise of new theories in microphysics Mario Bunge; 20. The incompleteness of quantum mechanics or the emperor's missing clothes H. R. Post; 21. How does a particle get from A to B?; Ted Bastin; 22. Informational generalization of entropy in physics Jerome Rothstein; 23. Can life explain quantum mechanics? H. H
Field-theory methods in coagulation theory
Lushnikov, A. A.
2011-08-15
Coagulating systems are systems of chaotically moving particles that collide and coalesce, producing daughter particles of mass equal to the sum of the masses involved in the respective collision event. The present article puts forth basic ideas underlying the application of methods of quantum-field theory to the theory of coagulating systems. Instead of the generally accepted treatment based on the use of a standard kinetic equation that describes the time evolution of concentrations of particles consisting of a preset number of identical objects (monomers in the following), one introduces the probability W(Q, t) to find the system in some state Q at an instant t for a specific rate of transitions between various states. Each state Q is characterized by a set of occupation numbers Q = (n{sub 1}, n{sub 2}, ..., n{sub g}, ...), where n{sub g} is the total number of particles containing precisely g monomers. Thereupon, one introduces the generating functional {Psi} for the probability W(Q, t). The time evolution of {Psi} is described by an equation that is similar to the Schroedinger equation for a one-dimensional Bose field. This equation is solved exactly for transition rates proportional to the product of the masses of colliding particles. It is shown that, within a finite time interval, which is independent of the total mass of the entire system, a giant particle of mass about the mass of the entire system may appear in this system. The particle in question is unobservable in the thermodynamic limit, and this explains the well-known paradox of mass-concentration nonconservation in classical kinetic theory. The theory described in the present article is successfully applied in studying the time evolution of random graphs.
NASA Astrophysics Data System (ADS)
Svozil, K.
1995-11-01
Inasmuch as physical theories are formalizable, set theory provides a framework for theoretical physics. Four speculations about the relevance of set theoretical modeling for physics are presented: the role of transcendental set theory (i) in chaos theory, (ii) for paradoxical decompositions of solid three-dimensional objects, (iii) in the theory of effective computability (Church-Turing thesis) related to the possible “solution of supertasks,” and (iv) for weak solutions. Several approaches to set theory and their advantages and disadvatages for physical applications are discussed: Canlorian “naive” (i.e., nonaxiomatic) set theory, contructivism, and operationalism. In the author's opinion, an attitude of “suspended attention” (a term borrowed from psychoanalysis) seems most promising for progress. Physical and set theoretical entities must be operationalized wherever possible. At the same time, physicists should be open to “bizarre” or “mindboggling” new formalisms, which need not be operationalizable or testable at the lime of their creation, but which may successfully lead to novel fields of phenomenology and technology.