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Sample records for rism theory distribution

  1. 3D RISM theory with fast reciprocal-space electrostatics

    SciTech Connect

    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.

  2. 3D RISM theory with fast reciprocal-space electrostatics.

    PubMed

    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. PMID:25796231

  3. Time-dependent density functional theory (TD-DFT) coupled with reference interaction site model self-consistent field explicitly including spatial electron density distribution (RISM-SCF-SEDD).

    PubMed

    Yokogawa, D

    2016-09-01

    Theoretical approach to design bright bio-imaging molecules is one of the most progressing ones. However, because of the system size and computational accuracy, the number of theoretical studies is limited to our knowledge. To overcome the difficulties, we developed a new method based on reference interaction site model self-consistent field explicitly including spatial electron density distribution and time-dependent density functional theory. We applied it to the calculation of indole and 5-cyanoindole at ground and excited states in gas and solution phases. The changes in the optimized geometries were clearly explained with resonance structures and the Stokes shift was correctly reproduced. PMID:27608983

  4. 3D-RISM-KH molecular theory of solvation and density functional theory investigation of the role of water in the aggregation of model asphaltenes.

    PubMed

    da Costa, L M; Hayaki, S; Stoyanov, S R; Gusarov, S; Tan, X; Gray, M R; Stryker, J M; Tykwinski, R; Carneiro, J Walkimar de M; Sato, H; Seidl, P R; Kovalenko, A

    2012-03-21

    We applied a multiscale modeling approach that involves the statistical-mechanical three-dimensional reference interaction site model with the Kovalenko-Hirata closure approximation (3D-RISM-KH molecular theory of solvation) as well as density functional theory (DFT) of electronic structure to study the role of water in aggregation of the asphaltene model compound 4,4'-bis(2-pyren-1-yl-ethyl)-2,2'-bipyridine (PBP) [X. Tan, H. Fenniri and M. R. Gray, Energy Fuels, 2008, 22, 715]. The solvation free energy and potential of mean force predicted by 3D-RISM-KH reveal favorable pathways for disaggregation of PBP dimers in pure versus water-saturated chloroform solvent. The water density distribution functions elucidate hydrogen bonding preferences and water bridge formation between PBP monomers. The ΔG(298) values of -5 to -7 kcal mol(-1) for transfer of water molecules in chloroform to a state interacting with PBP molecules are in agreement with experimental results. Geometry optimization and thermochemistry analysis of PBP dimers with and without water bridges using WB97Xd/6-31G(d,p) predict that both PBP dimerization and dimer stabilization by water bridges are spontaneous (ΔG(298) < 0). The (1)H NMR chemical shifts of PBP monomers and dimers predicted using the gauge-independent atomic orbital method and polarizable continuum model for solvation in chloroform are in an excellent agreement with the experimental results for dilute and concentrated PBP solutions in chloroform, respectively [X. Tan, H. Fenniri and M. R. Gray, Energy Fuels, 2009, 23, 3687]. The DFT calculations of PBP dimers with explicit water show that bridges containing 1-3 water molecules lead to stabilization of PBP dimers. Additional water molecules form hydrogen bonds with these bridges and de-shield the PBP protons, negating the effect of water on the (1)H(C3) NMR chemical shift of PBP, in agreement with experiment. The ΔG(298) results show that hydrogen bonding to water and water

  5. Estimating the Gibbs energy of hydration from molecular dynamics trajectories obtained by integral equations of the theory of liquids in the RISM approximation

    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.

  6. 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

  7. Modified Anderson Method for Accelerating 3D-RISM Calculations Using Graphics Processing Unit.

    PubMed

    Maruyama, Yutaka; Hirata, Fumio

    2012-09-11

    A fast algorithm is proposed to solve the three-dimensional reference interaction site model (3D-RISM) theory on a graphics processing unit (GPU). 3D-RISM theory is a powerful tool for investigating biomolecular processes in solution; however, such calculations are often both memory-intensive and time-consuming. We sought to accelerate these calculations using GPUs, but to work around the problem of limited memory size in GPUs, we modified the less memory-intensive "Anderson method" to give faster convergence to 3D-RISM calculations. Using this method on a Tesla C2070 GPU, we reduced the total computational time by a factor of 8, 1.4 times by the modified Andersen method and 5.7 times by GPU, compared to calculations on an Intel Xeon machine (eight cores, 3.33 GHz) with the conventional method. PMID:26605714

  8. Communication: Accurate hydration free energies at a wide range of temperatures from 3D-RISM.

    PubMed

    Misin, Maksim; Fedorov, Maxim V; Palmer, David S

    2015-03-01

    We present a new model for computing hydration free energies by 3D reference interaction site model (3D-RISM) that uses an appropriate initial state of the system (as suggested by Sergiievskyi et al.). The new adjustment to 3D-RISM theory significantly improves hydration free energy predictions for various classes of organic molecules at both ambient and non-ambient temperatures. An extensive benchmarking against experimental data shows that the accuracy of the model is comparable to (much more computationally expensive) molecular dynamics simulations. The calculations can be readily performed with a standard 3D-RISM algorithm. In our work, we used an open source package AmberTools; a script to automate the whole procedure is available on the web (https://github.com/MTS-Strathclyde/ISc). PMID:25747054

  9. Properties of a soft-core model of methanol: An integral equation theory and computer simulation study

    SciTech Connect

    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.

  10. Properties of a soft-core model of methanol: An integral equation theory and computer simulation study

    PubMed Central

    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

  11. Reference interaction site model with hydrophobicity induced density inhomogeneity: An analytical theory to compute solvation properties of large hydrophobic solutes in the mixture of polyatomic solvent molecules

    NASA Astrophysics Data System (ADS)

    Cao, Siqin; Sheong, Fu Kit; Huang, Xuhui

    2015-08-01

    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.

  12. Reference interaction site model with hydrophobicity induced density inhomogeneity: An analytical theory to compute solvation properties of large hydrophobic solutes in the mixture of polyatomic solvent molecules

    SciTech Connect

    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.

  13. MTS-MD of Biomolecules Steered with 3D-RISM-KH Mean Solvation Forces Accelerated with Generalized Solvation Force Extrapolation.

    PubMed

    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

  14. Improving the performance of the coupled reference interaction site model-hyper-netted chain (RISM-HNC)/simulation method for free energy of solvation.

    PubMed

    Freedman, Holly; Le, Ly; Tuszynski, Jack A; Truong, Thanh N

    2008-02-28

    The coupled reference interaction site model-hyper-netted chain (RISM-HNC)/ simulation methodology determines solvation free energies as a function of the set of all radial distribution functions of solvent atoms about atomic solute sites. These functions are determined from molecular dynamics (MD) or Monte Carlo (MC) simulations rather than from solving the RISM and HNC equations iteratively. Previous applications of the method showed that it can predict relative free energies of solvation for small solutes accurately. However, the errors scale with the system size. In this study, we propose the use of the hard-sphere free energy as the reference and a linear response approximation to improve the performance, i.e., accuracy and robustness, of the method, particularly removing the size dependency of the error. The details of the new formalism are presented. To validate the proposed formalism, solvation free energies of N-methylacetamide and methylamine are computed using the new RISM-HNC-based expressions in addition to a linear response expression, which are compared to previous thermodynamic integration and thermodynamic perturbation results performed with the same force field. Additionally, free energies of solvation for cyclohexane, pyridine, benzene and derivatives, and other small organic molecules are calculated and compared to experimental values. PMID:18251537

  15. Competitive interaction of monovalent cations with DNA from 3D-RISM.

    PubMed

    Giambaşu, George M; Gebala, Magdalena K; Panteva, Maria T; Luchko, Tyler; Case, David A; York, Darrin M

    2015-09-30

    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

  16. Competitive interaction of monovalent cations with DNA from 3D-RISM

    PubMed Central

    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

  17. Solvent dependence of Stokes shift for organic solute-solvent systems: A comparative study by spectroscopy and reference interaction-site model-self-consistent-field theory

    NASA Astrophysics Data System (ADS)

    Nishiyama, Katsura; Watanabe, Yasuhiro; Yoshida, Norio; Hirata, Fumio

    2013-09-01

    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.

  18. 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.

  19. Accurate prediction of explicit solvent atom distribution in HIV-1 protease and F-ATP synthase by statistical theory of liquids

    NASA Astrophysics Data System (ADS)

    Sindhikara, Daniel; Yoshida, Norio; Hirata, Fumio

    2012-02-01

    We have created a simple algorithm for automatically predicting the explicit solvent atom distribution of biomolecules. The explicit distribution is coerced from the 3D continuous distribution resulting from a 3D-RISM calculation. This procedure predicts optimal location of solvent molecules and ions given a rigid biomolecular structure. We show examples of predicting water molecules near KNI-275 bound form of HIV-1 protease and predicting both sodium ions and water molecules near the rotor ring of F-ATP synthase. Our results give excellent agreement with experimental structure with an average prediction error of 0.45-0.65 angstroms. Further, unlike experimental methods, this method does not suffer from the partial occupancy limit. Our method can be performed directly on 3D-RISM output within minutes. It is useful not only as a location predictor but also as a convenient method for generating initial structures for MD calculations.

  20. 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.

  1. A Cavity Corrected 3D-RISM Functional for Accurate Solvation Free Energies

    PubMed Central

    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

  2. A Cavity Corrected 3D-RISM Functional for Accurate Solvation Free Energies.

    PubMed

    Truchon, Jean-François; Pettitt, B Montgomery; Labute, Paul

    2014-03-11

    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

  3. TOPICS IN THEORY OF GENERALIZED PARTON DISTRIBUTIONS

    SciTech Connect

    Radyushkin, Anatoly V.

    2013-05-01

    Several topics in the theory of generalized parton distributions (GPDs) are reviewed. First, we give a brief overview of the basics of the theory of generalized parton distributions and their relationship with simpler phenomenological functions, viz. form factors, parton densities and distribution amplitudes. Then, we discuss recent developments in building models for GPDs that are based on the formalism of double distributions (DDs). A special attention is given to a careful analysis of the singularity structure of DDs. The DD formalism is applied to construction of a model GPDs with a singular Regge behavior. Within the developed DD-based approach, we discuss the structure of GPD sum rules. It is shown that separation of DDs into the so-called ``plus'' part and the $D$-term part may be treated as a renormalization procedure for the GPD sum rules. This approach is compared with an alternative prescription based on analytic regularization.

  4. APhoRISM FP7 project: the A Priori information for Earthquake damage mapping method

    NASA Astrophysics Data System (ADS)

    Bignami, Christian; Stramondo, Salvatore; Pierdicca, Nazzareno

    2014-05-01

    The APhoRISM - Advanced PRocedure for volcanIc and Seismic Monitoring - project is an FP7 funded project, which aims at developing and testing two new methods to combine Earth Observation satellite data from different sensors, and ground data for seismic and volcanic risk management. The objective is to demonstrate that this two types of data, appropriately managed and integrated, can provide new improved products useful for seismic and volcanic crisis management. One of the two methods deals with earthquakes, and it concerns the generation of maps to address the detection and estimate of damage caused by a seism. The method is named APE - A Priori information for Earthquake damage mapping. The use of satellite data to investigate earthquake damages is not an innovative issue. Indeed, a wide literature and projects have addressed and focused such issue, but usually the proposed approaches are only based on change detection techniques and/or classifications algorithms. The novelty of APhoRISM-APE relies on the exploitation of a priori information derived by: - InSAR time series to measure surface movements - shakemaps obtained from seismological data - vulnerability information. This a priori information is then integrated with change detection map from earth observation satellite sensors (either Optical or Synthetic Aperture Radar) to improve accuracy and to limit false alarms.

  5. A closure relation to molecular theory of solvation for macromolecules.

    PubMed

    Kobryn, Alexander E; Gusarov, Sergey; Kovalenko, Andriy

    2016-10-12

    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

  6. Solvation effects on chemical shifts by embedded cluster integral equation theory.

    PubMed

    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. PMID:25377116

  7. Analysis of solvation structure and thermodynamics of ethane and propane in water by reference interaction site model theory using all-atom models

    NASA Astrophysics Data System (ADS)

    Cui, Qizhi; Smith, Vedene H.

    2001-08-01

    Following our previous paper on methane [Cui and Smith, J. Chem. Phys. 113, 10240 (2000)], we study the solvation structures and thermodynamics of ethane and propane in water at the infinite dilution limit by using the hypernetted chain closure reference interaction site model (HNC-RISM) theory with all-atom representations for solute molecules. At four thermodynamic states: temperature T=283.15, 298.15, 313.15, 328.15 K and the corresponding bulk water density ρ=0.9997, 0.9970, 0.9922, 0.9875 g cm-3, all the atomic solute-solvent radial distribution functions are obtained, and the corresponding running coordination numbers and the hydration free energies, energies, enthalpies, and entropies are calculated with the radial distribution functions as input. The hydration structures of ethane and propane are presented and analyzed at the atomic level in terms of the atomic solute-solvent radial distribution functions. With the optimized nonbonded potential parameters based on the CHARMM96 all-atom model for alkanes [Yin and Mackerell, J. Comput. Chem. 19, 334 (1998)], the ethane and propane hydration thermodynamic properties predicted by the HNC-RISM theory are improved in the specified temperature range (10-55 °C).

  8. Applying Distributed Learning Theory in Online Business Communication Courses.

    ERIC Educational Resources Information Center

    Walker, Kristin

    2003-01-01

    Focuses on the critical use of technology in online formats that entail relatively new teaching media. Argues that distributed learning theory is valuable for teachers of online business communication courses for several reasons. Discusses the application of distributed learning theory to the teaching of business communication online. (SG)

  9. Diffraction Theory and Almost Periodic Distributions

    NASA Astrophysics Data System (ADS)

    Strungaru, Nicolae; Terauds, Venta

    2016-09-01

    We introduce and study the notions of translation bounded tempered distributions, and autocorrelation for a tempered distribution. We further introduce the spaces of weakly, strongly and null weakly almost periodic tempered distributions and show that for weakly almost periodic tempered distributions the Eberlein decomposition holds. For translation bounded measures all these notions coincide with the classical ones. We show that tempered distributions with measure Fourier transform are weakly almost periodic and that for this class, the Eberlein decomposition is exactly the Fourier dual of the Lebesgue decomposition, with the Fourier-Bohr coefficients specifying the pure point part of the Fourier transform. We complete the project by looking at few interesting examples.

  10. Distributed flexoelectric structural sensing: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Hu, S. D.; Li, H.; Tzou, H. S.

    2015-07-01

    "Distributed" sensors are sensitive to spatially distributed structural behaviors, as compared with conventional "discrete" sensors measuring only discrete and local behaviors. The phenomenon of electric polarization induced by strain gradients in solid dielectrics is known as the direct flexoelectric effect. In this study, distributed dynamic sensing using flexoelectric materials is proposed and the flexoelectric signal of distributed flexoelectric sensors laminated on an arbitrary shell structure is defined. Both the open-circuit and the close-circuit models of distributed flexoelectric sensing are developed. An equivalent flexoelectric constant is measured using the proposed open-circuit voltage model. Flexoelectric responses of various locations of a BST beam exhibit consistency and linearity in the case of small deflection. The inferred flexoelectric constant is comparable with the reported maximal coefficient and it also proves that the proposed model is effective to the flexoelectric constant measurement. Distributed sensing behaviors are also experimentally validated on the flexoelectric cantilever beam. Results show that theoretical predictions match well with the experimental results for the fundamental mode. Experiments of distributed sensing signals of beams suggest that distributed flexoelectric sensors are competent to provide the mode shape of strain gradients. Thus, distributed sensing based on the flexoelectric effect is effective to monitoring structural dynamic behaviors.

  11. 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.

  12. Small molecule hydration energy and entropy from 3D-RISM.

    PubMed

    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. PMID:27367817

  13. Raney Distributions and Random Matrix Theory

    NASA Astrophysics Data System (ADS)

    Forrester, Peter J.; Liu, Dang-Zheng

    2015-03-01

    Recent works have shown that the family of probability distributions with moments given by the Fuss-Catalan numbers permit a simple parameterized form for their density. We extend this result to the Raney distribution which by definition has its moments given by a generalization of the Fuss-Catalan numbers. Such computations begin with an algebraic equation satisfied by the Stieltjes transform, which we show can be derived from the linear differential equation satisfied by the characteristic polynomial of random matrix realizations of the Raney distribution. For the Fuss-Catalan distribution, an equilibrium problem characterizing the density is identified. The Stieltjes transform for the limiting spectral density of the singular values squared of the matrix product formed from inverse standard Gaussian matrices, and standard Gaussian matrices, is shown to satisfy a variant of the algebraic equation relating to the Raney distribution. Supported on , we show that it too permits a simple functional form upon the introduction of an appropriate choice of parameterization. As an application, the leading asymptotic form of the density as the endpoints of the support are approached is computed, and is shown to have some universal features.

  14. Fractal tracer distributions in turbulent field theories

    NASA Astrophysics Data System (ADS)

    Hansen, Jonas Lundbek; Bohr, Tomas

    1998-07-01

    We study the motion of passive tracers in a two-dimensional turbulent velocity field generated by the Kuramoto-Sivashinsky equation. By varying the direction of the velocity-vector with respect to the field-gradient we can continuously vary the two Lyapunov exponents for the particle motion and thereby find a regime in which the particle distribution is a strange attractor. We compare the Lyapunov dimension to the information dimension of actual particle distributions and show that there is good agreement with the Kaplan-Yorke conjecture. Similar phenomena have been observed experimentally.

  15. Theory of the Sea Ice Thickness Distribution.

    PubMed

    Toppaladoddi, Srikanth; Wettlaufer, J S

    2015-10-01

    We use concepts from statistical physics to transform the original evolution equation for the sea ice thickness distribution g(h) from Thorndike et al. into a Fokker-Planck-like conservation law. The steady solution is g(h)=N(q)h(q)e(-h/H), where q and H are expressible in terms of moments over the transition probabilities between thickness categories. The solution exhibits the functional form used in observational fits and shows that for h≪1, g(h) is controlled by both thermodynamics and mechanics, whereas for h≫1 only mechanics controls g(h). Finally, we derive the underlying Langevin equation governing the dynamics of the ice thickness h, from which we predict the observed g(h). The genericity of our approach provides a framework for studying the geophysical-scale structure of the ice pack using methods of broad relevance in statistical mechanics. PMID:26551827

  16. Theory of the Sea Ice Thickness Distribution

    NASA Astrophysics Data System (ADS)

    Toppaladoddi, Srikanth; Wettlaufer, J. S.

    2015-10-01

    We use concepts from statistical physics to transform the original evolution equation for the sea ice thickness distribution g (h ) from Thorndike et al. into a Fokker-Planck-like conservation law. The steady solution is g (h )=N (q )hqe-h /H, where q and H are expressible in terms of moments over the transition probabilities between thickness categories. The solution exhibits the functional form used in observational fits and shows that for h ≪1 , g (h ) is controlled by both thermodynamics and mechanics, whereas for h ≫1 only mechanics controls g (h ). Finally, we derive the underlying Langevin equation governing the dynamics of the ice thickness h , from which we predict the observed g (h ). The genericity of our approach provides a framework for studying the geophysical-scale structure of the ice pack using methods of broad relevance in statistical mechanics.

  17. 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.

  18. A new distributed sensor and actuator theory for ``Intelligent'' shells

    NASA Astrophysics Data System (ADS)

    Tzou, H. S.

    1992-03-01

    An " intelligent" shell is a shell structure with a self-sensation and action/reaction capabilities contributed by built-in sensors, actuators and control electronic systems. In this study, a new intelligent shell structure composed of a conventional elastic shell, a distributed piezoelectric sensor and a distributed piezoelectric actuator is proposed. The distributed sensor provides a self-monitoring capability to sense shell oscillation and the distributed actuator contributes a self-correction (control) capability to counteract the oscillation. A new generic theory for the intelligent shell system is developed. System equations of motion coupling sensing and control effects are derived. From the theory derived, it is concluded that the distributed sensor is (theoretically) capable of sensing all shell vibration modes and the distributed actuator controlling all shell modes. However, the sensing or control effort of each mode could be different. Two feedback control algorithms, namely direct feedback control and Lyapunov control, are proposed in the paper. The generic theory can be simplified to account for other general geometries, such as cylinder, plates, beams, etc. Applications of the theory are also demonstrated.

  19. Towards a simple mathematical theory of citation distributions.

    PubMed

    Katchanov, Yurij L

    2015-01-01

    The paper is written with the assumption that the purpose of a mathematical theory of citation is to explain bibliometric regularities at the level of mathematical formalism. A mathematical formalism is proposed for the appearance of power law distributions in social citation systems. The principal contributions of this paper are an axiomatic characterization of citation distributions in terms of the Ekeland variational principle and a mathematical exploration of the power law nature of citation distributions. Apart from its inherent value in providing a better understanding of the mathematical underpinnings of bibliometric models, such an approach can be used to derive a citation distribution from first principles. PMID:26558180

  20. 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.

  1. General theory for apparent energy distribution of sea waves

    NASA Astrophysics Data System (ADS)

    Wu, Ke-Jian; Sun, Fu

    1997-12-01

    This paper presents a general theory for the apparent energy distribution of sea waves. Using the joint distribution of wave periods and heights proposed earlier by the second author, the authors define the generalized apparent energy distribution and derive the analytical form of the so called generalized outer frequency spectrum or nth-order frequency spectrum. Some possible relationships between it and the Fourier frequency spectrum are discussed. It is shown that the widely used Bretschneider spectrum can be easily obtained from the above definition and that generalized outer frequency spectrum has equilibrium range with exponent -( n+3) whose upper limit is -3.

  2. LEDS theory of workhardening stages and planar versus distributed glide

    NASA Astrophysics Data System (ADS)

    Kuhlmann-Wilsdorf, D.; Wilsdorf, H. G. F.; Wert, J. A.

    1994-09-01

    From a widespread convention, glide in crystalline materials is classified as 'planar' versus 'distributed'. At elevated temperatures, 'distributed glide' is favored and is almost usually found at medium to high strains in pure metals, in low-concentration homogeneous alloys, and in a preponderance of multiphase alloys, provided temperatures are not too low. While at low temperatures, 'planar glide' is widely observed and favored in solid solution alloys. In this paper, a general explanation is presented over the proposed additional causes for planar versus distributed glide, based on the LEDS theory.

  3. A geometric theory for Lévy distributions

    NASA Astrophysics Data System (ADS)

    Eliazar, Iddo

    2014-08-01

    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.

  4. A geometric theory for Lévy distributions

    SciTech Connect

    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.

  5. Structural parameters of glycine zwitterion hydration from the data of the integral equation method in the RISM approach

    NASA Astrophysics Data System (ADS)

    Fedotova, M. V.; Kruchinin, S. E.

    2012-12-01

    The structural parameters of glycine zwitterion in water were studied by means of the integral equation method in the framework of the RISM approximation. According to calculations, five water molecules are located in the nearest environment of the -NH{3/+} group, and two of them are the H-bonded with this group. At the same time, six water molecules are located in the nearest environment of the -COO- group, and three of them are the H-bonded with this group. The average number of water molecules in the first hydration shell of -CH2 group is four. It has been shown that the probability of hydrogen bond formation between water molecules and the hydrogen atom H1 of the -NH{3/+} group is low, and there is no H-bonding between water molecules and the nitrogen atom the -NH{3/+} group.

  6. Pólya distribution and its asymptotics in nucleation theory

    NASA Astrophysics Data System (ADS)

    Dubrovskii, V. G.

    2014-02-01

    A model of condensation-decay rate constants that are linear with respect to the number of monomers in the nucleus is considered. In a particular case of stable growth, this model leads to an exact solution of discrete kinetic equations of the theory of heterogeneous nucleation in the form of the Pólya distribution function. An asymptotic solution in the region of large nucleus sizes that satisfies the normalization condition and provides correct mean nucleus size has been found. It is shown that, in terms of the logarithmic invariant size, the obtained distribution has a universal time-independent form. The obtained solution, being more general than the double-exponent distribution used previously, describes both Gaussian and asymmetric distributions depending on the rate constant of condensation on a bare core. The obtained results are useful for modeling processes in some systems, in particular, the growth of linear chains, two-dimensional clusters, and filamentary nanocrystals.

  7. 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.

  8. Predicting the binding free energy of the inclusion process of 2-hydroxypropyl-β-cyclodextrin and small molecules by means of the MM/3D-RISM method.

    PubMed

    Sugita, Masatake; Hirata, Fumio

    2016-09-28

    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. PMID:27452185

  9. Predicting the binding free energy of the inclusion process of 2-hydroxypropyl-β-cyclodextrin and small molecules by means of the MM/3D-RISM method

    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.

  10. Extracting water and ion distributions from solution x-ray scattering experiments.

    PubMed

    Nguyen, Hung T; Pabit, Suzette A; Pollack, Lois; Case, David A

    2016-06-01

    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. PMID:27276943

  11. Distributed Inference in Tree Networks Using Coding Theory

    NASA Astrophysics Data System (ADS)

    Kailkhura, Bhavya; Vempaty, Aditya; Varshney, Pramod K.

    2015-07-01

    In this paper, we consider the problem of distributed inference in tree based networks. In the framework considered in this paper, distributed nodes make a 1-bit local decision regarding a phenomenon before sending it to the fusion center (FC) via intermediate nodes. We propose the use of coding theory based techniques to solve this distributed inference problem in such structures. Data is progressively compressed as it moves towards the FC. The FC makes the global inference after receiving data from intermediate nodes. Data fusion at nodes as well as at the FC is implemented via error correcting codes. In this context, we analyze the performance for a given code matrix and also design the optimal code matrices at every level of the tree. We address the problems of distributed classification and distributed estimation separately and develop schemes to perform these tasks in tree networks. The proposed schemes are of practical significance due to their simple structure. We study the asymptotic inference performance of our schemes for two different classes of tree networks: fixed height tree networks, and fixed degree tree networks. We show that the proposed schemes are asymptotically optimal under certain conditions.

  12. 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.

  13. Pion momentum distributions in the nucleon in chiral effective theory

    SciTech Connect

    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.

  14. Orbit Limited Theory in the Solar Wind - kappa Distributions

    NASA Astrophysics Data System (ADS)

    Martinović, M. M.

    2016-06-01

    When a solid object is immersed into ionized gas it gets brought to a certain value of electrostatic potential and surrounded by a space charge region called `plasma sheath'. Through this region, particles are attracted or repelled from the surface of the charge collecting object. For collisionless plasma, this process is described by the so-called orbit limited theory, which explains how the collection of particles is determined by the collector geometry and plasma velocity distribution function (VDF). In this article, we provide explicit orbit-limited currents expressions for generalized Lorentzian (κ) distributions. This work is useful to describe the charging processes of objects in non-collisional plasmas like the solar wind, where the electrons VDF is often observed to exhibit quasi power-law populations of suprathermal particles. It is found that these 'suprathermals' considerably increase the charge collection. Since the surface charging process that determines the value of electrostatic potential is also affected by the plasma VDF, calculation of the collector potential in the solar wind is described along with some quantitative predictions.

  15. Fast and General Method To Predict the Physicochemical Properties of Druglike Molecules Using the Integral Equation Theory of Molecular Liquids.

    PubMed

    Palmer, David S; Mišin, Maksim; Fedorov, Maxim V; Llinas, Antonio

    2015-09-01

    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. PMID:26212723

  16. On the electron equilibrium distribution function in the kinetic theory of electron cyclotron maser

    NASA Astrophysics Data System (ADS)

    Shenggang, Liu

    1981-11-01

    The problems concerning the specification of electron equilibrium distribution function for the kinetic theory of ECRM are investigated in this paper. After detailed analysis of the published equilibium distribution functions, several conclusion have been achieved.

  17. Application of integral equation theory to polyolefin liquids and blends

    SciTech Connect

    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.

  18. Computation of electromagnetic scattering parameters for lognormal distributions of magnetic spheres: Theory and algorithms

    NASA Astrophysics Data System (ADS)

    Milham, Merrill E.

    1994-10-01

    In this report, relevant parts of the scattering theory for magnetic spheres are presented. Mass extinction coefficients, and the lognormal size distribution are defined. The theory and algorithms for integrating scattering parameters over size distributions are developed. The integrations are carried out in terms of dimensionless scattering, and size distribution parameters, which are simply related to the usual mass scattering coefficients. Fortran codes, which implement the algorithmic design, are presented, and examples of code use are given. Code listings are included.

  19. Reference interaction site model and optimized perturbation theories of colloidal dumbbells with increasing anisotropy

    SciTech Connect

    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.

  20. 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…

  1. 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…

  2. Three-dimensional molecular theory of solvation coupled with molecular dynamics in Amber

    PubMed Central

    Luchko, Tyler; Gusarov, Sergey; Roe, Daniel R.; Simmerling, Carlos; Case, David A.; Tuszynski, Jack; Kovalenko, Andriy

    2010-01-01

    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 multi-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. PMID:20440377

  3. Percolation Theory for the Distribution and Abundance of Species

    NASA Astrophysics Data System (ADS)

    He, Fangliang; Hubbell, Stephen P.

    2003-11-01

    We develop and test new models that unify the mathematical relationships among the abundance of a species, the spatial dispersion of the species, the number of patches occupied by the species, the edge length of the occupied patches, and the scale on which the distribution of species is mapped. The models predict that species distributions will exhibit percolation critical thresholds, i.e., critical population abundances at which the fragmented patches (as measured by the number of patches and edge length) start to coalesce to form large patches.

  4. 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…

  5. 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.

  6. Theory of Nanocluster Size Distributions from Ion Beam Synthesis

    SciTech Connect

    Yuan, C.W.; Yi, D.O.; Sharp, I.D.; Shin, S.J.; Liao, C.Y.; Guzman, J.; Ager III, J.W.; Haller, E.E.; Chrzan, D.C.

    2008-06-13

    Ion beam synthesis of nanoclusters is studied via both kinetic Monte Carlo simulations and the self-consistent mean-field solution to a set of coupled rate equations. Both approaches predict the existence of a steady state shape for the cluster size distribution that depends only on a characteristic length determined by the ratio of the effective diffusion coefficient to the ion flux. The average cluster size in the steady state regime is determined by the implanted species/matrix interface energy.

  7. Theory predicts the uneven distribution of genetic diversity within species.

    PubMed

    Rauch, Erik M; Bar-Yam, Yaneer

    2004-09-23

    Global efforts to conserve species have been strongly influenced by the heterogeneous distribution of species diversity across the Earth. This is manifest in conservation efforts focused on diversity hotspots. The conservation of genetic diversity within an individual species is an important factor in its survival in the face of environmental changes and disease. Here we show that diversity within species is also distributed unevenly. Using simple genealogical models, we show that genetic distinctiveness has a scale-free power law distribution. This property implies that a disproportionate fraction of the diversity is concentrated in small sub-populations, even when the population is well-mixed. Small groups are of such importance to overall population diversity that even without extrinsic perturbations, there are large fluctuations in diversity owing to extinctions of these small groups. We also show that diversity can be geographically non-uniform--potentially including sharp boundaries between distantly related organisms--without extrinsic causes such as barriers to gene flow or past migration events. We obtained these results by studying the fundamental scaling properties of genealogical trees. Our theoretical results agree with field data from global samples of Pseudomonas bacteria. Contrary to previous studies, our results imply that diversity loss owing to severe extinction events is high, and focusing conservation efforts on highly distinctive groups can save much of the diversity. PMID:15386012

  8. Item Response Theory with Estimation of the Latent Population Distribution Using Spline-Based Densities

    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…

  9. Distribution theory for Schrödinger’s integral equation

    SciTech Connect

    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.

  10. 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.

  11. Liquid state theories for the structure of water

    NASA Astrophysics Data System (ADS)

    Reddy, Govardhan; Lawrence, C. P.; Skinner, J. L.; Yethiraj, Arun

    2003-12-01

    Liquid state theories are investigated for the local structure of the simple point charge (SPC) and a modified SPC (MSPC) model of water. The latter model includes a van der Waals repulsion between the oxygen (O) and hydrogen (H) atoms, which is necessary for the implementation of some integral equation theories. Two integral equation theories, the reference interaction site model (RISM) and the diagrammatically proper Chandler-Silbey-Ladanyi (CSL) theory, are tested by comparison with simulations of the MSPC model (neither theory converges for the SPC model when the hypernetted chain closure is used). The RISM theory is in reasonable agreement with simulations, and is more accurate than the CSL theory. A density functional theory (DFT) is investigated, which treats the ideal gas functional exactly and uses a truncated expansion for the excess free energy functional. The DFT is in excellent agreement with simulations for the structure of the MSPC water model at all temperatures studied, and for the structure of the SPC water model at high temperatures. At room temperature, the DFT is in good agreement with simulations (of SPC water) for gHH(r) and gOH(r), but misses the location of the second peak in gOO(r). We attribute this deficiency to the importance of three-body correlations that are not properly incorporated in the theory.

  12. Effects of conformational distributions on sigma profiles in COSMO theories.

    PubMed

    Wang, Shu; Stubbs, John M; Siepmann, J Ilja; Sandler, Stanley I

    2005-12-15

    The charge density or sigma profile of a solute molecule is an essential component in COSMO (conductor-like screen model) based solvation theories, and its generation depends on the molecular conformation used. The usual procedure is to determine the conformation of an isolated molecule, and assume that this is unchanged when the molecule is placed in solution. In this paper, the conformations of 1-hexanol and 2-methoxy-ethanol in both the liquid and vapor phases obtained from Gibbs ensemble simulation and from an isolated-molecule quantum DFT optimization are used to determine the effect of realistic conformation differences on COSMO-based properties predictions. In particular, the vapor pressure at the normal boiling temperature and the binary mixture VLE (vapor-liquid equilibrium) predictions obtained using different conformations are investigated. The results show that the sigma profile for 1-hexanol varies only slightly using the different conformations, while the sigma profile of 2-methoxy-ethanol shows a significant difference between the liquid and vapor phases. Consequently, the vapor pressure predictions for 1-hexanol are similar regardless of the manner in which the conformation population was obtained, while there is a larger difference for 2-methoxy-ethanol depending on whether the liquid or vapor conformations from simulation or the DFT-optimized structure is used. These differences in predictions are seen to be largely due to differences in the ideal solvation energy term. In mixture VLE calculations involving 1-hexanol, we again see that there is little difference in the phase equilibrium predictions among the different conformations, while for the mixture with 2-methoxy-ethanol, the differences in the sigma profiles lead to a more noticeable, though not significant, difference in the phase equilibrium predictions. PMID:16331913

  13. Evaluating Ecohydrological Theories of Woody Root Distribution in the Kalahari

    PubMed Central

    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

  14. Second order classical perturbation theory for atom surface scattering: Analysis of asymmetry in the angular distribution

    SciTech Connect

    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.

  15. Dense medium radiative transfer theory for two scattering layers with a Rayleigh distribution of particle sizes

    SciTech Connect

    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.

  16. Electric Interfacial Layer of Modified Cellulose Nanocrystals in Aqueous Electrolyte Solution: Predictions by the Molecular Theory of Solvation.

    PubMed

    Lyubimova, Olga; Stoyanov, Stanislav R; Gusarov, Sergey; Kovalenko, Andriy

    2015-06-30

    The X-ray crystal structure-based models of Iα cellulose nanocrystals (CNC), both pristine and containing surface sulfate groups with negative charge 0-0.34 e/nm(2) produced by sulfuric acid hydrolysis of softwood pulp, feature a highly polarized "crystal-like" charge distribution. We perform sampling using molecular dynamics (MD) of the structural relaxation of neutral pristine and negatively charged sulfated CNC of various lengths in explicit water solvent and then employ the statistical mechanical 3D-RISM-KH molecular theory of solvation to evaluate the solvation structure and thermodynamics of the relaxed CNC in ambient aqueous NaCl solution at a concentration of 0.0-0.25 mol/kg. The MD sampling induces a right-hand twist in CNC and rearranges its initially ordered structure with a macrodipole of high-density charges at the opposite faces into small local spots of alternating charge at each face. This surface charge rearrangement observed for both neutral and charged CNC significantly affects the distribution of ions around CNC in aqueous electrolyte solution. The solvation free energy (SFE) of charged sulfated CNC has a minimum at a particular electrolyte concentration depending on the surface charge density, whereas the SFE of neutral CNC increases linearly with NaCl concentration. The SFE contribution from Na(+) counterions exhibits behavior similar to the NaCl concentration dependence of the whole SFE. An analysis of the 3D maps of Na(+) density distributions shows that these model CNC particles exhibit the behavior of charged nanocolloids in aqueous electrolyte solution: an increase in electrolyte concentration shrinks the electric interfacial layer and weakens the effective repulsion between charged CNC particles. The 3D-RISM-KH method readily treats solvent and electrolyte of a given nature and concentration to predict effective interactions between CNC particles in electrolyte solution. We provide CNC structural models and a modeling procedure for

  17. Small-signal theory of subterahertz overmoded surface wave oscillator with distributed wall loss

    NASA Astrophysics Data System (ADS)

    Wang, Guangqiang; Wang, Jianguo; Li, Shuang; Wang, Xuefeng

    2015-09-01

    A small-signal theory of the overmoded surface wave oscillator (SWO) with distributed wall loss is presented in this letter. The wall loss considered here includes the surface resistance and surface roughness. The cold and hot characteristics of 0.14 THz SWO are studied by the small-signal theory. Numerical results show that as the increase of wall loss, the working frequency decreases slightly, the rise time and startup time of oscillation increase significantly, and the output power decreases dramatically. Particle-in-cell (PIC) simulation confirms the prediction by the small-signal theory.

  18. The Distribution of the Product Explains Normal Theory Mediation Confidence Interval Estimation

    PubMed Central

    Kisbu-Sakarya, Yasemin; MacKinnon, David P.; Miočević, Milica

    2014-01-01

    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. PMID:25554711

  19. Non-static conformally flat spherically symmetric perfect fluid distribution in Einstein-Cartan theory

    NASA Astrophysics Data System (ADS)

    Yadav, R. B. S.; Prasad, U.

    1993-05-01

    The nonstatic conformally flat spherically symmetric perfect fluid distribution in Einstein-Cartan theory is considered, and the field equations and their general solution are obtained using Hehl's approach (1974). Particular attention is given to the solution in co-moving coordinates and the explicit expressions for pressure, density, expansion, rotation, and shear and nonzero components of flow vector.

  20. Conformally flat static spherically symmetric perfect-fluid distribution in Einstein-Cartan theory

    NASA Astrophysics Data System (ADS)

    Kalyanshetti, S. B.; Waghmode, B. B.

    1983-06-01

    We consider the static, conformally flat spherically symmetric perfect-fluid distribution in Einstein-Cartan theory and obtain the field equations. These field equations are solved by adopting Hehl's approach with the assumption that the spins of the particles composing the fluid are all aligned in the radial direction only and the reality conditions are discussed.

  1. The Feynman integrand as a white noise distribution beyond perturbation theory

    SciTech Connect

    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.

  2. 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…

  3. A Security Proof of Measurement Device Independent Quantum Key Distribution: From the View of Information Theory

    NASA Astrophysics Data System (ADS)

    Li, Fang-Yi; Yin, Zhen-Qiang; Li, Hong-Wei; Chen, Wei; Wang, Shuang; Wen, Hao; Zhao, Yi-Bo; Han, Zheng-Fu

    2014-07-01

    Although some ideal quantum key distribution protocols have been proved to be secure, there have been some demonstrations that practical quantum key distribution implementations were hacked due to some real-life imperfections. Among these attacks, detector side channel attacks may be the most serious. Recently, a measurement device independent quantum key distribution protocol [Phys. Rev. Lett. 108 (2012) 130503] was proposed and all detector side channel attacks are removed in this scheme. Here a new security proof based on quantum information theory is given. The eavesdropper's information of the sifted key bits is bounded. Then with this bound, the final secure key bit rate can be obtained.

  4. On the theory of wing sections with particular reference to the lift distribution

    NASA Technical Reports Server (NTRS)

    Theodorsen, Theodore

    1932-01-01

    This report gives a simple and exact method of calculating the lift distribution on thin wing sections. The most essential feature of the new theory is the introduction of an "ideal angle of attack," this angle being defined as that at which the flow enters the leading edge smoothly or, more precisely, as the angle of attack at which the lift at the leading edge equals zero. The lift distribution at this particular angle is shown to be a characteristic property of the section and has been termed the "basic distribution." it is shown that the lift of a wing section may always be considered to consist of (a) the basic distribution and (b) the additional distribution, where the latter is independent of the mean camber line and thus identical for all thin sections. The specific reason for the poor aerodynamic qualities of thin wing sections is pointed out as being due to the fact that the additional lift in potential flow becomes infinite at the leading edge. It is established that the essential parameter occurring in this analysis is the radius of curvature at the leading edge. It is further established that the actual slope of the lift curve is dependent on this parameter. The theoretical lift distribution is compared with the distribution obtained by direct measurement on a number of the more conventional wing sections. The new theory is of value in calculating the strength of wing sections.

  5. 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.

  6. 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.

  7. 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.

  8. Multiple time step molecular dynamics in the optimized isokinetic ensemble steered with the molecular theory of solvation: Accelerating with advanced extrapolation of effective solvation forces

    SciTech Connect

    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

  9. Probability distribution of the index in gauge theory on 2d non-commutative geometry

    NASA Astrophysics Data System (ADS)

    Aoki, Hajime; Nishimura, Jun; Susaki, Yoshiaki

    2007-10-01

    We investigate the effects of non-commutative geometry on the topological aspects of gauge theory using a non-perturbative formulation based on the twisted reduced model. The configuration space is decomposed into topological sectors labeled by the index ν of the overlap Dirac operator satisfying the Ginsparg-Wilson relation. We study the probability distribution of ν by Monte Carlo simulation of the U(1) gauge theory on 2d non-commutative space with periodic boundary conditions. In general the distribution is asymmetric under ν mapsto -ν, reflecting the parity violation due to non-commutative geometry. In the continuum and infinite-volume limits, however, the distribution turns out to be dominated by the topologically trivial sector. This conclusion is consistent with the instanton calculus in the continuum theory. However, it is in striking contrast to the known results in the commutative case obtained from lattice simulation, where the distribution is Gaussian in a finite volume, but the width diverges in the infinite-volume limit. We also calculate the average action in each topological sector, and provide deeper understanding of the observed phenomenon.

  10. 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.

  11. Equilibrium distribution of hard-sphere systems and revised Enskog theory

    NASA Astrophysics Data System (ADS)

    van Beijeren, H.

    1983-10-01

    A revised Enskog theory (RET) is shown to lead to a correct equilibrium distribution in hard-sphere systems in a stationary external potential, while the standard Enskog theory (SET) does not. Attention is given to the s-component hard-sphere mixture with constant external potential acting on particles of a particular species. The different definition of the pair correlation function at a contact point of two different species used in RET is demonstrated to be consistent with equilibrium statistical mechanics, whereas the definition chosen for the contact point in SET is not.

  12. 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.

  13. Non-Markovian theory for the waiting time distributions of single electron transfers.

    PubMed

    Welack, Sven; Yan, YiJing

    2009-09-21

    We derive a non-Markovian theory for waiting time distributions of consecutive single electron transfer events. The presented microscopic Pauli rate equation formalism couples the open electrodes to the many-body system, allowing to take finite bias and temperature into consideration. Numerical results reveal transient oscillations of distinct system frequencies due to memory in the waiting time distributions. Memory effects can be approximated by an expansion in non-Markovian corrections. This method is employed to calculate memory landscapes displaying preservation of memory over multiple consecutive electron transfers. PMID:19778104

  14. Predicting photoemission intensities and angular distributions with real-time density-functional theory

    NASA Astrophysics Data System (ADS)

    Dauth, M.; Kümmel, S.

    2016-02-01

    Photoemission spectroscopy is one of the most frequently used tools for characterizing the electronic structure of condensed matter systems. We discuss a scheme for simulating photoemission from finite systems based on time-dependent density-functional theory. It allows for the first-principles calculation of relative electron binding energies, ionization cross sections, and anisotropy parameters. We extract these photoemission spectroscopy observables from Kohn-Sham orbitals propagated in real time. We demonstrate that the approach is capable of estimating photoemission intensities, i.e., peak heights. It can also reliably predict the angular distribution of photoelectrons. For the example of benzene we contrast calculated angular distribution anisotropy parameters to experimental reference data. Self-interaction free Kohn-Sham theory yields meaningful outer valence single-particle states in the right energetic order. We discuss how to properly choose the complex absorbing potential that is used in the simulations.

  15. 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.

  16. Normal loads program for aerodynamic lifting surface theory. [evaluation of spanwise and chordwise loading distributions

    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.

  17. Number density distribution of solvent molecules on a substrate: a transform theory for atomic force microscopy.

    PubMed

    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. PMID:27080590

  18. Investigating the Impact of Item Parameter Drift for Item Response Theory Models with Mixture Distributions

    PubMed Central

    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

  19. Investigating the Impact of Item Parameter Drift for Item Response Theory Models with Mixture Distributions.

    PubMed

    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

  20. Proceedings of the Workshop on Applications of Distributed System Theory to the Control of Large Space Structures

    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.

  1. Theory and calculation of water distribution in bentonite in a thermal field

    SciTech Connect

    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.

  2. 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.

  3. 3D-RISM-MP2 Approach to Hydration Structure of Pt(II) and Pd(II) Complexes: Unusual H-Ahead Mode vs Usual O-Ahead One.

    PubMed

    Aono, Shinji; Mori, Toshifumi; Sakaki, Shigeyoshi

    2016-03-01

    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

  4. On the theory of intensity distributions of tornadoes and other low pressure systems

    NASA Astrophysics Data System (ADS)

    Schielicke, Lisa; Névir, Peter

    Approaching from a theoretical point of view, this work presents a theory which unifies intensity distributions of different low pressure systems, based on an energy of displacement. Resulting from a generalized Boltzmann distribution, the expression of this energy of displacement is obtained by radial integration over the forces which are in balance with the pressure gradient force in the horizontal equation of motion. A scale analysis helps to find out which balance of forces prevail. According to the prevailing balances, the expression of the energy of displacement differs for various depressions. Investigating the system at the moment of maximum intensity, the energy of displacement can be interpreted as the work that has to be done to generate and finally eliminate the pressure anomaly, respectively. By choosing the appropriate balance of forces, number-intensity (energy of displacement) distributions show exponential behavior with the same decay rate β for tornadoes and cyclones, if tropical and extra-tropical cyclones are investigated together. The decay rate is related to a characteristic (universal) scale of the energy of displacement which has approximately the value Eu = β- 1 ≈ 1000 m 2s - 2 . In consequence, while the different balances of forces cause the scales of velocity, the energy of displacement scale seems to be universal for all low pressure systems. Additionally, if intensity is expressed as lifetime minimum pressure, the number-intensity (pressure) distributions should be power law distributed. Moreover, this work points out that the choice of the physical quantity which represents the intensity is important concerning the behavior of intensity distributions. Various expressions of the intensity like velocity, kinetic energy, energy of displacement and pressure are possible, but lead to different behavior of the distributions.

  5. 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.

  6. Kinetic theory of the filamentation instability in a collisional current-driven plasma with nonextensive distribution

    SciTech Connect

    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.

  7. The Evolution of Grain Size Distribution in Explosive Rock Fragmentation - Sequential Fragmentation Theory Revisited

    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

  8. Neutral theory and the species abundance distribution: recent developments and prospects for unifying niche and neutral perspectives.

    PubMed

    Matthews, Thomas J; Whittaker, Robert J

    2014-06-01

    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

  9. Neutral theory and the species abundance distribution: recent developments and prospects for unifying niche and neutral perspectives

    PubMed Central

    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

  10. Sediment residence time distributions: Theory and application from bed elevation measurements

    NASA Astrophysics Data System (ADS)

    Voepel, Hal; Schumer, Rina; Hassan, Marwan A.

    2013-12-01

    distance and residence time probability distributions are the key components of stochastic models for coarse sediment transport. Residence time for individual grains is difficult to measure, and residence time distributions appropriate to field and laboratory settings are typically inferred theoretically or from overall transport characteristics. However, bed elevation time series collected using sonar transducers and lidar can be translated into empirical residence time distributions at each elevation in the bed and for the entire bed thickness. Sediment residence time at a given depth can be conceptualized as a stochastic return time process on a finite interval. Overall sediment residence time is an average of residence times at all depths weighted by the likelihood of deposition at each depth. Theory and experiment show that when tracers are seeded on the bed surface, power law residence time will be observed until a timescale set by the bed thickness and bed fluctuation statistics. After this time, the long-time (global) residence time distribution will take exponential form. Crossover time is the time of transition from power law to exponential behavior. The crossover time in flume studies can be on the order of seconds to minutes, while that in rivers can be days to years.

  11. Applications of the theory of optimal control of distributed-parameter systems to structural optimization

    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.

  12. Moving beyond abundance distributions: neutral theory and spatial patterns in a tropical forest

    PubMed Central

    May, Felix; Huth, Andreas; Wiegand, Thorsten

    2015-01-01

    Assessing the relative importance of different processes that determine the spatial distribution of species and the dynamics in highly diverse plant communities remains a challenging question in ecology. Previous modelling approaches often focused on single aggregated forest diversity patterns that convey limited information on the underlying dynamic processes. Here, we use recent advances in inference for stochastic simulation models to evaluate the ability of a spatially explicit and spatially continuous neutral model to quantitatively predict six spatial and non-spatial patterns observed at the 50 ha tropical forest plot on Barro Colorado Island, Panama. The patterns capture different aspects of forest dynamics and biodiversity structure, such as annual mortality rate, species richness, species abundance distribution, beta-diversity and the species–area relationship (SAR). The model correctly predicted each pattern independently and up to five patterns simultaneously. However, the model was unable to match the SAR and beta-diversity simultaneously. Our study moves previous theory towards a dynamic spatial theory of biodiversity and demonstrates the value of spatial data to identify ecological processes. This opens up new avenues to evaluate the consequences of additional process for community assembly and dynamics. PMID:25631991

  13. Estimating Non-Normal Latent Trait Distributions within Item Response Theory Using True and Estimated Item Parameters

    ERIC Educational Resources Information Center

    Sass, D. A.; Schmitt, T. A.; Walker, C. M.

    2008-01-01

    Item response theory (IRT) procedures have been used extensively to study normal latent trait distributions and have been shown to perform well; however, less is known concerning the performance of IRT with non-normal latent trait distributions. This study investigated the degree of latent trait estimation error under normal and non-normal…

  14. SEM with Missing Data and Unknown Population Distributions Using Two-Stage ML: Theory and Its Application

    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…

  15. Kinetic theory of dust ion acoustic waves in a kappa-distributed plasma

    NASA Astrophysics Data System (ADS)

    Baluku, T. K.; Hellberg, M. A.

    2015-08-01

    Using a kinetic theory approach, dust ion acoustic (DIA) waves are investigated in an unmagnetized collisionless plasma with kappa-distributed electrons and ions, and Maxwellian dust grains of constant charge. Both analytical and numerical results, the latter following from the full solution of the associated dispersion relation, are presented, and a comparison is made. The effects of the ion and electron spectral indices, as well as the species' density ( ne/ni ) and temperature ( Te/Ti ) ratios, on the dispersion and damping of the waves are considered. In the long wavelength regime, increases in both the electron spectral index (κe) and the dust density fraction (reduced f =ne/ni ) lead to an increase in phase velocity. The range in wavelength over which modes are weakly damped increases with an increase in Te/Ti . However, the ion spectral index, κi, does not have a significant effect on the dispersion or damping of DIA waves.

  16. Calculation of photodetachment cross sections and photoelectron angular distributions of negative ions using density functional theory

    NASA Astrophysics Data System (ADS)

    Liu, Yuan; Ning, Chuangang

    2015-10-01

    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.

  17. Effect of Electron Energy Distribution on the Hysteresis of Plasma Discharge: Theory, Experiment, and Modeling

    PubMed Central

    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

  18. Biased theories of galaxy formation with arbitrary threshold functions and background distribution

    NASA Astrophysics Data System (ADS)

    Borgani, Stefano; Bonometto, Silvio A.

    1990-01-01

    The technical aspects of considering non-theta thresholds within the framework of biased theories of galaxy formation are discussed, without restricting the treatment to background Gaussian matter distribution. First, non-Gaussian backgrounds and non-theta thresholds are simultaneously considered. Then a number of other features are accounted for through suitable forms of threshold functions. Two specific examples of non-theta thresholds relate directly to the effects of nonspherical gravitational growing and a possible merging of fluctuations on different mass scales during the growing stages. It appears that these effects become stronger for mass scales corresponding to Abell cluster mass scale range. In particular, the threshold related to nonsphericity makes the observed number densities of Turner and Gott groups and Abell cluster naturally coherent.

  19. Homogenization theory for periodic distributions of elastic cylinders embedded in a viscous fluid.

    PubMed

    Reyes-Ayona, Edgar; Torrent, Daniel; Sánchez-Dehesa, José

    2012-10-01

    A multiple-scattering theory is applied to study the homogenization of clusters of elastic cylinders distributed in a isotropic lattice and embedded in a viscous fluid. Asymptotic relations are derived and employed to obtain analytical formulas for the effective parameters of homogenized clusters in which the underlying lattice has a low filling fraction. It is concluded that such clusters behave, in the low frequency limit, as an effective elastic medium. Particularly, it is found that the effective dynamical mass density follows the static estimate; i.e., the homogenization procedure does not recover the non-linear behavior obtained for the inviscid case. Moreover, the longitudinal and transversal sound speeds do not show any dependence on fluid viscosity. Numerical simulations performed for clusters made of brass cylinders embedded in glycerin support the reliability of the effective parameters resulting from the homogenization procedure reported here. PMID:23039556

  20. Hydrogen Balmer alpha intensity distributions and line profiles from multiple scattering theory using realistic geocoronal models

    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.

  1. Effect of Electron Energy Distribution on the Hysteresis of Plasma Discharge: Theory, Experiment, and Modeling

    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.

  2. Distribution function approach to redshift space distortions. Part V: perturbation theory applied to dark matter halos

    NASA Astrophysics Data System (ADS)

    Vlah, Zvonimir; Seljak, Uroš; Okumura, Teppei; Desjacques, Vincent

    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.

  3. Revisiting the pion leading-twist distribution amplitude within the QCD background field theory

    NASA Astrophysics Data System (ADS)

    Zhong, Tao; Wu, Xing-Gang; Wang, Zhi-Gang; Huang, Tao; Fu, Hai-Bing; Han, Hua-Yong

    2014-07-01

    We study the pion leading-twist distribution amplitude (DA) within the framework of Shifman-Vainshtein-Zakharov sum rules under the background field theory. To improve the accuracy of the sum rules, we expand both the quark propagator and the vertex (z.D↔)n of the correlator up to dimension-six operators in the background field theory. The sum rules for the pion DA moments are obtained, in which all condensates up to dimension-six have been taken into consideration. Using the sum rules, we obtain ⟨ξ2⟩|1 GeV=0.338±0.032, ⟨ξ4⟩|1GeV=0.211±0.030 and ⟨ξ6⟩|1GeV=0.163±0.030. It is shown that the dimension-six condensates shall provide sizable contributions to the pion DA moments. We show that the first Gegenbauer moment of the pion leading-twist DA is a2π|1 GeV=0.403±0.093, which is consistent with those obtained in the literature within errors but prefers a larger central value as indicated by lattice QCD predictions.

  4. The Theory of Super-Resolution Electron Microscopy Via Wigner-Distribution Deconvolution

    NASA Astrophysics Data System (ADS)

    Rodenburg, J. M.; Bates, R. H. T.

    1992-06-01

    The theory of deconvolving the microdiffraction data-set available in a scanning transmission electron microscope or, equivalently, the set of all bright- and dark-field images available in a conventional transmission electron microscope to obtain superresolution micrographs (which are not limited by the transfer function of the objective lens) is developed and described with reference to holography and other phase-retrieval schemes. By the use of a Wigner distribution, influences of the instrument function can be entirely separated from the information pertaining to the specimen. The final solution yields an unambiguous estimate of the complex value of the specimen function at a resolution which in theory is only limited by the electron wavelength. The faithfulness of the image processing is shown to be not seriously affected by specimen thickness or partial coherence in the illuminating beam. The inversion procedure is remarkably noise insensitive, implying that it should result in a robust and practicable experimental technique, though one that will require very large computing facilities.

  5. Distribution function approach to redshift space distortions. Part V: perturbation theory applied to dark matter halos

    SciTech Connect

    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.

  6. A theory of local and global processes which affect solar wind electrons. 1: The origin of typical 1 AU velocity distribution functions: Steady state theory

    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.

  7. Non-Gaussianities in the topological charge distribution of the SU(3) Yang-Mills theory

    NASA Astrophysics Data System (ADS)

    Cè, Marco; Consonni, Cristian; Engel, Georg P.; Giusti, Leonardo

    2015-10-01

    We study the topological charge distribution of the SU(3) Yang-Mills theory with high precision in order to be able to detect deviations from Gaussianity. The computation is carried out on the lattice with high statistics Monte Carlo simulations by implementing a naive discretization of the topological charge evolved with the Yang-Mills gradient flow. This definition is far less demanding than the one suggested from Neuberger's fermions and, as shown in this paper, in the continuum limit its cumulants coincide with those of the universal definition appearing in the chiral Ward identities. Thanks to the range of lattice volumes and spacings considered, we can extrapolate the results for the second and fourth cumulant of the topological charge distribution to the continuum limit with confidence by keeping finite volume effects negligible with respect to the statistical errors. Our best results for the topological susceptibility is t02χ =6.67 (7 )×1 0-4 , where t0 is a standard reference scale, while for the ratio of the fourth cumulant over the second, we obtain R =0.233 (45 ). The latter is compatible with the expectations from the large Nc expansion, while it rules out the θ behavior of the vacuum energy predicted by the dilute instanton model. Its large distance from 1 implies that, in the ensemble of gauge configurations that dominate the path integral, the fluctuations of the topological charge are of quantum nonperturbative nature.

  8. 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.

  9. The distribution of cell surface proteins on spreading cells. Comparison of theory with experiment.

    PubMed Central

    Goldstein, B; Wiegel, F W

    1988-01-01

    Bretscher (1983) has shown that on uniformly spread giant HeLa cells, the receptors for low density lipoprotein (LDL) and transferrin are concentrated toward the periphery of the cells. To explain these nonuniform distributions, he proposed that on giant HeLa cells, recycling receptors return to the cell surface at the cell's leading edge. Since the distribution of coated pits on these cells is uniform, Bretscher and Thomson (1983) proposed that there is a bulk membrane flow toward the cell centers. Here we present a mathematical model that allows us to predict the distribution of cell surface proteins on a thin circular cell, when exocytosis occurs at the cell periphery and endocytosis occurs uniformly over the cell surface. We show that on such a cell, a bulk membrane flow will be generated, whose average velocity is zero at the cell center and increases linearly with the distance from the cell center. Our model predicts that proteins that aggregate in coated pits will have concentrations that are maximal at the cell periphery. We fit our theory to the data of Bretscher and Thomson (1983) on the distribution of ferritin receptors for the following cases: the receptors move by diffusion alone; they move by bulk membrane flow alone; they move by a combination of diffusion and bulk membrane flow. From our fits we show that tau m greater than 3.5 tau p, where tau m and tau p are the lifetimes of the membrane and the ferritin receptor on the cell surface, and that tau pD less than 6.9 X 10(-7) cm2, where D is the ferritin receptor diffusion coefficient. Surprisingly, we obtain the best fits to the data when we neglect membrane flow. Our model predicts that for proteins that are excluded from coated pits, the protein concentration will be Gaussian, being maximal at the cell center and decreasing with the distance from the cell center. If on giant HeLa cells a protein with such a distribution could be found, it would strongly support Bretcher's proposal that there is an

  10. Neutron distribution, electric dipole polarizability and weak form factor of 48Ca from chiral effective field theory

    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.

  11. The self-preserving size distribution theory. II. Comparison with experimental results for Si and Si3N4 aerosols.

    PubMed

    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. PMID:16290535

  12. Force-Field Functor Theory: Classical Force-Fields which Reproduce Equilibrium Quantum Distributions

    NASA Astrophysics Data System (ADS)

    Babbush, Ryan; Parkhill, John; Aspuru-Guzik, Alan

    2013-10-01

    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.

  13. Force-field functor theory: classical force-fields which reproduce equilibrium quantum distributions

    PubMed Central

    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

  14. Electric-field distribution near rectangular microstrip radiators for hyperthermia heating: theory versus experiment in water.

    PubMed

    Underwood, H R; Peterson, A F; Magin, R L

    1992-02-01

    A rectangular microstrip antenna radiator is investigated for its near-zone radiation characteristics in water. Calculations of a cavity model theory are compared with the electric-field measurements of a miniature nonperturbing diode-dipole E-field probe whose 3 mm tip was positioned by an automatic three-axis scanning system. These comparisons have implications for the use of microstrip antennas in a multielement microwave hyperthermia applicator. Half-wavelength rectangular microstrip patches were designed to radiate in water at 915 MHz. Both low (epsilon r = 10) and high (epsilon r = 85) dielectric constant substrates were tested. Normal and tangential components of the near-zone radiated electric field were discriminated by appropriate orientation of the E-field probe. Low normal to transverse electric-field ratios at 3.0 cm depth indicate that the radiators may be useful for hyperthermia heating with an intervening water bolus. Electric-field pattern addition from a three-element linear array of these elements in water indicates that phase and amplitude adjustment can achieve some limited control over the distribution of radiated power. PMID:1612617

  15. Electric-field distribution near rectangular microstrip radiators for hyperthermia heating: Theory versus experiment in water

    SciTech Connect

    Underwood, H.R. ); Peterson, A.F. ); Magin, R.L. )

    1992-02-01

    A rectangular microstrip antenna radiator is investigated for its near-zone radiation characteristics in water. Calculations of a cavity model theory are compared with the electric-field measurements of a miniature nonperturbing diode dipole E-field probe whose 3 mm tip was positioned by an automatic three-axis scanning system. These comparisons have implications for the use of microstrip antennas in a multielement microwave hyperthermia applicator. Half-wavelength rectangular microstrip patches were designed to radiate in water at 915 MHz. Both low ([epsilon][sub r] = 10) and high ([epsilon][sub r] = 85) dielectric constant substrates were tested. Normal and tangential components of the near-zone radiated electric field were discriminated by appropriate orientation of the E-field probe. Low normal to transverse electric-field ratios ar 3.0 cm depth indicate that the radiators may be useful for hyperthermia heating with an intervening water bolus. Electric-field pattern addition from a three-element linear array of these elements in water indicates that phase and amplitude adjustment can achieve some limited control over the distribution of radiated power.

  16. Calculation of photodetachment cross sections and photoelectron angular distributions of negative ions using density functional theory

    SciTech Connect

    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.

  17. Population Validity and Cross-Validity: Applications of Distribution Theory for Testing Hypotheses, Setting Confidence Intervals, and Determining Sample Size

    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.)

  18. A theory of local and global processes which affect solar wind electrons. I - The origin of typical 1 AU velocity distribution functions - Steady state theory

    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).

  19. Distribution function approach to redshift space distortions. Part IV: perturbation theory applied to dark matter

    SciTech Connect

    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.

  20. Simultaneous distribution between the deflection angle and the lateral displacement under the Molière theory of multiple scattering

    NASA Astrophysics Data System (ADS)

    Nakatsuka, Takao; Okei, Kazuhide; Iyono, Atsushi; Bielajew, Alex F.

    2015-12-01

    Simultaneous distribution between the deflection angle and the lateral displacement of fast charged particles traversing through matter is derived by applying numerical inverse Fourier transforms on the Fourier spectral density solved analytically under the Molière theory of multiple scattering, taking account of ionization loss. Our results show the simultaneous Gaussian distribution at the region of both small deflection angle and lateral displacement, though they show the characteristic contour patterns of probability density specific to the single and the double scatterings at the regions of large deflection angle and/or lateral displacement. The influences of ionization loss on the distribution are also investigated. An exact simultaneous distribution is derived under the fixed energy condition based on a well-known model of screened single scattering, which indicates the limit of validity of the Molière theory applied to the simultaneous distribution. The simultaneous distribution will be valuable for improving the accuracy and the efficiency of experimental analyses and simulation studies relating to charged particle transports.

  1. 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

  2. Niche and metabolic principles explain patterns of diversity and distribution: theory and a case study with soil bacterial communities.

    PubMed

    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. PMID:26019154

  3. Scalable implementation of analytic gradients for second-order Z-averaged perturbation theory using the distributed data interface.

    PubMed

    Aikens, Christine M; Fletcher, Graham D; Schmidt, Michael W; Gordon, Mark S

    2006-01-01

    The analytic gradient expression for second-order Z-averaged perturbation theory is revised and its parallel implementation is described in detail. The distributed data interface is used to access molecular-orbital integral arrays stored in distributed memory. The algorithm is designed to maximize the use of local data and reduce communication costs. The iterative solution and the preconditioner used to induce the convergence of the coupled-perturbed Hartree-Fock equations are presented. Several illustrative timing examples are discussed. PMID:16409024

  4. A Novel Wide-Area Backup Protection Based on Fault Component Current Distribution and Improved Evidence Theory

    PubMed Central

    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

  5. Mean-Field Theories for Terrace-Width Distributions of Vicinal Surfaces: Beyond the Generalized Wigner Distribution

    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.

  6. ETHOS—an effective theory of structure formation: From dark particle physics to the matter distribution of the Universe

    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.

  7. Evaluating the Use of Random Distribution Theory to Introduce Statistical Inference Concepts to Business Students

    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…

  8. Modeling optical properties of human skin using Mie theory for particles with different size distributions and refractive indices

    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.

  9. A quantitative theory for the mean velocity distribution of compressible ramp flow

    NASA Astrophysics Data System (ADS)

    Bi, Wei-Tao; Wu, Bin; Zou, Hong-Yue; Li, Xin-Liang; Hussain, Fazle; She, Zhen-Su

    2013-11-01

    The flow induced by a compression ramp is of practical importance as a typical flow in the intake of a scramjet engine, yet no quantitative theory is available. This study proposes a quantitative theory for the mean velocity profile (MVP) of the compression ramp flow, based on a multi-layer description of turbulent boundary layers. Application of the theory on the direct numerical simulation (DNS) data shows that the mixing length function in the boundary layer after the reattachment point has a five-layer structure. A formula is given for the streamwise MVP, in very good agreement with the DNS data. Variation of the parameters in the formula with the spatial position is measured and discussed. These results further support the validity of the Structural Ensemble Dynamics approach to a wide class of wall-bounded flows, and a new modeling strategy for engineering computation of complex supersonic flows.

  10. Statistical Continuum Theory for the Effective Conductivity of Fiber Filled Polymer Composites: Effect of Orientation Distribution and Aspect Ratio

    SciTech Connect

    Mikdam, Amed; Makradi, A.; Ahzi, Said; Garmestani, Hamid; Li, Dongsheng; Remond, Y.

    2010-03-01

    Effective conductivity of polymer composites, filled with conducting fibers such as carbon nanotubes, is studied using statistical continuum theory. The fiber orientation distribution in the matrix plays a very important role on their effective properties. To take into account their orientation, shape and distribution, two-point and three-point probability distribution functions are used. The effect of fibers orientation is illustrated by comparing the effective conductivity of microstructures with oriented and non-oriented fibers. The randomly oriented fibers result in an isotropic effective conductivity. The increased fiber orientation distribution can lead to higher anisotropy in conductivity. The effect of fiber’s aspect ratio on the effective conductivity is studied by comparing microstructures with varying degrees of fiber orientation distribution. Results show that the increase in anisotropy leads to higher conductivity in the maximum fiber orientation distribution direction and lower conductivity in the transverse direction. These results are in agreement with various models from the literature that show the increase of the aspect ratio of fibers improves the electrical and thermal conductivity.

  11. 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

  12. Particle size distributions and the sequential fragmentation/transport theory applied to volcanic ash

    SciTech Connect

    Wohletz, K.H. ); Sheridan, M.F. ); Brown, W.K. )

    1989-11-10

    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: {ital n}({ital l})={ital kl}{sup {alpha}} exp(-{ital l}{beta}), where {ital n}({ital l}) represents the number of particles of diameter {ital l}, {ital l} is the normalized particle diameter, and {ital k}, {alpha}, and {beta} 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 {ital m}{prime}: {ital n}({ital x}, {ital m})={ital C} {integral}{integral} {ital n}({ital x}{prime}, {ital m}{prime}){ital p}({xi}) {ital dx}{prime} {ital dm}{prime}, where {ital x}{prime} denotes spatial location along a linear axis, {ital C} is a constant, and integration is performed over distance from an origin to the sample location and mass limits from 0 to {ital m}.

  13. Maximum entropy principle based estimation of performance distribution in queueing theory.

    PubMed

    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. PMID:25207992

  14. 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.

  15. Particle size distributions and the sequential fragmentation/transport theory applied to volcanic ash

    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

  16. Space and time distribution of HF excited Langmuir turbulence in the ionosphere: Comparison of theory and experiment

    NASA Astrophysics Data System (ADS)

    Dubois, D. F.; Hanssen, Alfred; Rose, Harvey A.; Russell, David

    1993-10-01

    The predictions of strong Langmuir turbulence (SLT) theory are compared with radar observations of HF induced turbulence at Arecibo and Tromsø. The altitude distribution of turbulence observed in the cold start experiments of Fejer et al. (1991) imply that the ionospheric electron density profile is modified by the induced turbulence. The preconditioned observations at Arecibo and the Tromsø observations also appear to require a ``disturbed'' profile with several percent density fluctuations. With such density modifications postulated we conclude that 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. We 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.

  17. Para-hydrogen and helium cluster size distributions in free jet expansions based on Smoluchowski theory with kernel scaling

    SciTech Connect

    Kornilov, Oleg; Toennies, J. Peter

    2015-02-21

    The size distribution of para-H{sub 2} (pH{sub 2}) clusters produced in free jet expansions at a source temperature of T{sub 0} = 29.5 K and pressures of P{sub 0} = 0.9–1.96 bars is reported and analyzed according to a cluster growth model based on the Smoluchowski theory with kernel scaling. Good overall agreement is found between the measured and predicted, N{sub k} = A k{sup a} e{sup −bk}, shape of the distribution. The fit yields values for A and b for values of a derived from simple collision models. The small remaining deviations between measured abundances and theory imply a (pH{sub 2}){sub k} magic number cluster of k = 13 as has been observed previously by Raman spectroscopy. The predicted linear dependence of b{sup −(a+1)} on source gas pressure was verified and used to determine the value of the basic effective agglomeration reaction rate constant. A comparison of the corresponding effective growth cross sections σ{sub 11} with results from a similar analysis of He cluster size distributions indicates that the latter are much larger by a factor 6-10. An analysis of the three body recombination rates, the geometric sizes and the fact that the He clusters are liquid independent of their size can explain the larger cross sections found for He.

  18. 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.

  19. Current distribution in a three-dimensional IC analyzed by a perturbation method. Part 1: A simple steady state theory

    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.

  20. Alfvénic oscillations of the electron distribution function: Linear theory and experimental measurements

    SciTech Connect

    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.

  1. 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.

  2. Particle multiplicity distributions: Connections with a Feynman-Wilson gas and a Ginzburg-Landau theory

    NASA Astrophysics Data System (ADS)

    Mekjian, A. Z.

    2002-01-01

    Particle yields and fluctuations are studied in a general framework based on a cycle class picture in a Feynman path integral approach. Various cases such as the disoriented chiral condensate distribution, a negative binomial distribution, partially coherent state emission, and field emission from Lorentzian line shapes are discussed. Generalizations based on these important specific cases are developed. Connections of the cycle class picture with other approaches based on combinants, cumulants, hierarchical models, and clan variables are presented for the specific and general cases. A relation to a Feynman-Wilson gas and to the Ginzburg-Landau model are discussed.

  3. Deviation from the Forster theory for time-dependent donor decays for randomly distributed molecules in solution

    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.

  4. Wigner distribution function and entropy of the damped harmonic oscillator within the theory of the open quantum systems

    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.

  5. Statistical distribution of the vacuum energy density in racetrack Kähler uplift models in string theory

    NASA Astrophysics Data System (ADS)

    Sumitomo, Yoske; Tye, S.-H. Henry; Wong, Sam S. C.

    2013-07-01

    We study a racetrack model in the presence of the leading α'-correction in flux compactification in Type IIB string theory, for the purpose of getting conceivable de-Sitter vacua in the large compactified volume approximation. Unlike the Kähler Uplift model studied previously, the α'-correction is more controllable for the meta-stable de-Sitter vacua in the racetrack case since the constraint on the compactified volume size is very much relaxed. We find that the vacuum energy density Λ for de-Sitter vacua approaches zero exponentially as the volume grows. We also analyze properties of the probability distribution of Λ in this class of models. As in other cases studied earlier, the probability distribution again peaks sharply at Λ = 0. We also study the Racetrack Kähler Uplift model in the Swiss-Cheese type model.

  6. Angular distributions of electrons photoemitted from core levels of oriented diatomic molecules: Multiple scattering theory in non-spherical potentials

    SciTech Connect

    Diez Muino, R.; Rolles, D.; Garcia de Abajo, F.J.; Fadley, C.S.; Van Hove, M.A.

    2001-09-06

    We use multiple scattering in non-spherical potentials (MSNSP) to calculate the angular distributions of electrons photoemitted from the 1s-shells of CO and N2 gas-phase molecules with fixed-in-space orientations. For low photoelectron kinetic energies (E<50 eV), as appropriate to certain shape-resonances, the electron scattering must be represented by non-spherical scattering potentials, which are naturally included in our formalism. Our calculations accurately reproduce the experimental angular patterns recently measured by several groups, including those at the shape-resonance energies. The MSNSP theory thus enhances the sensitivity to spatial electronic distribution and dynamics, paving the way toward their determination from experiment.

  7. Pion production via proton synchrotron radiation in strong magnetic fields in relativistic field theory: Scaling relations and angular distributions

    NASA Astrophysics Data System (ADS)

    Maruyama, Tomoyuki; Cheoun, Myung-Ki; Kajino, Toshitaka; Mathews, Grant J.

    2016-06-01

    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 ni,f ∼104-105. 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 1015 G, where ni,f ∼1012-1013, from the results for ni,f ∼104-105. The resultant pion intensity and angular distributions for realistic magnetic field strengths are presented and their physical implications discussed.

  8. Pion production via proton synchrotron radiation in strong magnetic fields in relativistic field theory: Scaling relations and angular distributions

    NASA Astrophysics Data System (ADS)

    Maruyama, Tomoyuki; Cheoun, Myung-Ki; Kajino, Toshitaka; Mathews, Grant J.

    2016-06-01

    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 ni,f ∼104-105. 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 1015 G, where ni,f ∼1012-1013, from the results for ni,f ∼104-105. The resultant pion intensity and angular distributions for realistic magnetic field strengths are presented and their physical implications discussed.

  9. Assumed strain distributions for a finite strip plate bending element using Mindlin-Reissner plate theory

    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.

  10. Future climate projections of extreme precipitation and temperature distributions by using an Extreme Value Theory non-stationary model

    NASA Astrophysics Data System (ADS)

    Casati, B.; Lefaivre, L.

    2009-04-01

    Extreme weather events can cause large damages and losses, and have high societal and economical impacts. Climate model integrations predict increases in both frequency and intensity of extreme events under enhanced greenhouse conditions. Better understanding of the capabilities of climate models in representing the present climate extremes, joint with the analysis of the future climate projections for extreme events, can help to forewarn society from future high-impact events, and possibly better develop adaptation strategies. Extreme Value Theory (EVT) provides a well established and robust framework to analyse the behaviour of extreme weather events for the present climate and future projections. In this study a non-stationary model for Generalised Extreme Value (GEV) distributions is used to analyse the trend of the distributions of extreme precipitation and temperatures, in the context of a changing climate. The analysis is performed for the climate projections of the Canadian Regional Climate Model (CRCM), under a SRES A2 emission scenario, for annual, seasonal and monthly extremes, for 12 regions characterised by different climatologies over the North American domain. Significant positive trends for the location of the distributions are found in most regions, indicating an expected increase in extreme value intensities, whereas the scale (variability) and shape (tail values) of the extreme distributions seem not to vary significantly. Extreme events, such as intense convective precipitation, are often associated to small-scale features. The enhanced resolution of Regional Climate Models enables to better represent such extreme events, with respect to Global Climate Models. However the resolution of these models is sometimes still too coarse to reproduce realistic extremes. To address this representativeness issue, statistical downscaling of the CRCM projections is performed. The downscaling relation is obtained by comparing the GEV distributions for the CRCM

  11. 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.

  12. 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., 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.

  13. Application of wavelet theory to power distribution systems for fault detection

    SciTech Connect

    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.

  14. Pseudorational Impulse Responses — Algebraic System Theory for Distributed Parameter Systems

    NASA Astrophysics Data System (ADS)

    Yamamoto, Yutaka

    This paper gives a comprehensive account on a class of distributed parameter systems, whose impulse response is called pseudorational. This notion was introduced by the author in 1980's, and is particularly amenable for the study of systems with bounded-time memory. We emphasize algebraic structures induced by this class of systems. Some recent results on coprimeness issues and H∞ control are discussed and illustrated.

  15. Muscle diffraction theory. Relationship between diffraction subpeaks and discrete sarcomere length distributions.

    PubMed Central

    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

  16. Development of molecular closures for the reference interaction site model theory with application to square-well and Lennard-Jones homonuclear diatomics.

    PubMed

    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. PMID:27548461

  17. Predictions of polarized multilayer theory of solute distribution confirmed from a study of the equilibrium distribution in frog muscle of twenty-one nonelectrolytes including five cryoprotectants.

    PubMed

    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

  18. Control of a Flexible Space Antenna: A Finite Dimensional Perspective Based on Distributed Parameter Theory

    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.

  19. Phenomenological theory of structural relaxation based on a thermorheologically complex relaxation time distribution

    NASA Astrophysics Data System (ADS)

    Andreozzi, L.; Faetti, M.; Salmerã³n Sanchez, M.; Gã³mez Ribelles, J. L.

    2008-09-01

    The aim of this work is to explore the consequences on the kinetics of structural relaxation of considering a glass-forming system to consist of a series of small but macroscopic relaxing regions that evolve independently from each other towards equilibrium in the glassy state. The result of this assumption is a thermorheologically complex model. In this approach each relaxing zone has been assumed to follow the Scherer-Hodge model for structural relaxation (with the small modification of taking a linear dependence of configurational heat capacity with temperature). The model thus developed contains four fitting parameters. A least-squares search routine has been used to find the set of model parameters that fit simultaneously four DSC thermograms in PVAc after different thermal histories. The computer-simulated curves are compared with those obtained with Scherer-Hodge model and the model proposed by Gómez and Monleón. The evolution of the relaxation times during cooling or heating scans and also during isothermal annealing below the glass transition has been analysed. It has been shown that the relaxation times distribution narrows in the glassy state with respect to equilibrium. Isothermal annealing causes this distribution to broaden during the process to finally attain in equilibrium the shape defined at temperatures above Tg.

  20. Microwave heating power distribution in electron-cyclotron resonance processing plasmas, experiment and theory

    SciTech Connect

    Douglass, S.R.; Eddy, C. Jr.; Lampe, M.; Joyce, G.; Slinker, S.; Weber, B.V.

    1995-12-31

    The authors are currently investigating the mechanisms of microwave power absorption in an ECR plasma. The microwave electric field is detected with an antenna at the end of a shielded co-ax cable, connected to a bolometer for power measurements. Initial measurements have been 1-D along the axis of the plasma chamber. Later, 3-D profiles will be made of the microwave heating power distribution. A comparison of the experimental results with the theoretical microwave absorption are presented. A ray tracing analysis of the propagating right hand wave are given, including both collisional and collisionless absorption. Mode conversion effects are studied to explain why most of the power is absorbed at the entry window, especially the L wave power.

  1. Reference hypernetted chain theory for ferrofluid bilayer: distribution functions compared with Monte Carlo.

    PubMed

    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. PMID:25173007

  2. Application of statistical distribution theory to launch-on-time for space construction logistic support

    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.

  3. Fission fragment charge and mass distributions in 239Pu(n ,f ) in the adiabatic nuclear energy density functional theory

    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

  4. 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.

  5. Comparing ligo merger rate observations with theory: distribution of star-forming conditions

    SciTech Connect

    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

  6. Application of the integral equation theory of polymers: Distribution function, chemical potential, and mean expansion coefficient

    NASA Astrophysics Data System (ADS)

    Gan, Hin Hark; Eu, Byung Chan

    1993-09-01

    A recursive integral equation for the intramolecular correlation function of an isolated linear polymer of N bonds is derived from the integral equations presented in the preceding paper. The derivation basically involves limiting the density of the polymer to zero so that polymers do not interact with each other, and thus taking into account the intramolecular part only. The integral equation still has the form of a generalized Percus-Yevick integral equation. The intramolecular correlation function of a polymer of N bonds is recursively generated by means of it from those of polymers of 2, 3,..., (N-1) bonds. The end-to-end distance distribution functions are computed by using the integral equation for various chain lengths, temperatures, and bond lengths in the case of a repulsive soft-sphere potential. Numerical solutions of the recursive integral equation yield universal exponents for the mean square end-to-end distance in two and three dimensions with values which are close to the Flory results: 0.77 and 0.64 vs Flory's values 0.75 and 0.6 for two and three dimensions, respectively. The intramolecular correlation functions computed can be fitted with displaced Gaussian forms. The N dependence of the internal chemical potential is found to saturate after some value of N depending on the ratio of the bond length to the bead radius.

  7. Kinetic theory of phase space plateaux in a non-thermal energetic particle distribution

    SciTech Connect

    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.

  8. Verification of Anderson superexchange in MnO via magnetic pair distribution function analysis and ab initio theory

    DOE PAGESBeta

    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 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

  9. Verification of Anderson Superexchange in MnO via Magnetic Pair Distribution Function Analysis and ab initio Theory

    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.

  10. Verification of Anderson Superexchange in MnO via Magnetic Pair Distribution Function Analysis and ab initio Theory.

    PubMed

    Frandsen, Benjamin A; Brunelli, Michela; Page, Katharine; Uemura, Yasutomo J; Staunton, Julie B; Billinge, Simon J L

    2016-05-13

    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. PMID:27232042

  11. The van Hove distribution function for Brownian hard spheres: Dynamical test particle theory and computer simulations for bulk dynamics

    NASA Astrophysics Data System (ADS)

    Hopkins, Paul; Fortini, Andrea; Archer, Andrew J.; Schmidt, Matthias

    2010-12-01

    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.

  12. The van Hove distribution function for brownian hard spheres: dynamical test particle theory and computer simulations for bulk dynamics.

    PubMed

    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. PMID:21171689

  13. Fertility, income distribution, and economic growth: theory and cross-country evidence.

    PubMed

    Galor, O; Zang, H

    1997-05-01

    The authors perform discriminatory, empirical tests of a theoretical model that predicts that family size adversely affects output per capita and nonsteady state growth rates. Neoclassical models posit that adverse output and nonsteady growth rates are affected by labor force growth (LFG) or population growth (PG). This study tests whether family size (FS) will be more significant than LFG or PG in explaining differences in economic growth (EG) rates across countries during 1960-88. A proxy variable for the public education system was used to separate government interventions on human capital formation from market forces. Data were obtained for 73 countries, which exclude centrally planned economies, oil-producing countries, and those with less than 1 million population. The empirical test is run with 58-country, 45-country, and 96-country samples to test for robustness and reliability. The empirical test supports the theoretical model. It demonstrates that equal distribution of income and smaller FS enhance EG. With income inequality, the effect of FS was significant, and the effect of the LFG rate or PG rate was insignificant. With a given FS, LFG was positively correlated with EG. A reduction of the net fertility rate by one point would increase the worker output growth rate by 0.25%, and the differences in growth rates between high- and low-fertility countries would be 1%. An increase in the income share of the bottom 60% would increase the growth rate of worker output by about 1%. Higher investments in public or private education would be conducive to growth. PMID:12321036

  14. Integral equation theory of the structure and thermodynamics of polymer blends

    NASA Astrophysics Data System (ADS)

    Schweizer, Kenneth S.; Curro, John G.

    1989-10-01

    Our recently developed RISM integral equation theory of the structure and thermodynamics of homopolymer melts is generalized to polymer mixtures. The mean spherical approximation (MSA) closure to the generalized Ornstein-Zernike equations is employed, in conjunction with the neglect of explicit chain end effects and the assumption of ideality of intramolecular structure. The theory is developed in detail for binary blends, and the random phase approximation (RPA) form for concentration fluctuation scattering is rigorously obtained by enforcing incompressibility. A microscopic, wave vector-dependent expression for the effective chi parameter measured in small angle neutron scattering (SANS) experiments is derived in terms of the species-dependent direct correlation functions of the blend. The effective chi parameter is found to depend, in general, on thermodynamic state, intermolecular forces, intramolecular structure, degree of polymerization, and global architecture. The relationship between the mean field Flory-Huggins expression for the free energy of mixing and our RISM-MSA theory is determined, along with general analytical connections between the chi parameter and intermolecular pair correlations in the liquid. Detailed numerical applications to athermal and isotopic chain polymer blend models are presented for both the chi parameter and the structure. For athermal blends a negative, concentration-dependent chi parameter is found which decreases with density, structural asymmetry, and increases with molecular weight. For isotopic blends, the effective (positive) chi parameter is found to be strongly renormalized downward from its mean field enthalpic value by long range fluctuations in monomer concentration induced by polymeric connectivity and excluded volume. Both the renormalization and composition dependence of the chi parameter increase with chain length and proximity to the spinodal instability. The critical temperature is found to be proportional to

  15. Unveiling the species-rank abundance distribution by generalizing the Good-Turing sample coverage theory.

    PubMed

    Chao, Anne; Hsieh, T C; Chazdon, Robin L; Colwell, Robert K; Gotelli, Nicholas J

    2015-05-01

    Based on a sample of individuals, we focus on inferring the vector of species relative abundance of an entire assemblage and propose a novel estimator of the complete species-rank abundance distribution (RAD). Nearly all previous estimators of the RAD use the conventional "plug-in" estimator Pi (sample relative abundance) of the true relative abundance pi of species i. Because most biodiversity samples are incomplete, the plug-in estimators are applied only to the subset of species that are detected in the sample. Using the concept of sample coverage and its generalization, we propose a new statistical framework to estimate the complete RAD by separately adjusting the sample relative abundances for the set of species detected in the sample and estimating the relative abundances for the set of species undetected in the sample but inferred to be present in the assemblage. We first show that P, is a positively biased estimator of pi for species detected in the sample, and that the degree of bias increases with increasing relative rarity of each species. We next derive a method to adjust the sample relative abundance to reduce the positive bias inherent in j. The adjustment method provides a nonparametric resolution to the longstanding challenge of characterizing the relationship between the true relative abundance in the entire assemblage and the observed relative abundance in a sample. Finally, we propose a method to estimate the true relative abundances of the undetected species based on a lower bound of the number of undetected species. We then combine the adjusted RAD for the detected species and the estimated RAD for the undetected species to obtain the complete RAD estimator. Simulation results show that the proposed RAD curve can unveil the true RAD and is more accurate than the empirical RAD. We also extend our method to incidence data. Our formulas and estimators are illustrated using empirical data sets from surveys of forest spiders (for abundance data) and

  16. Multidisciplinary design optimisation of a recurve bow based on applications of the autogenetic design theory and distributed computing

    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.

  17. Pion production via proton synchrotron radiation in strong magnetic fields in relativistic field theory: Scaling relations and angular distributions

    DOE PAGESBeta

    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 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

  18. Could refuge theory and rivers acting as barriers explain the genetic variability distribution in the Atlantic Forest?

    PubMed

    Cazé, Ana Luiza R; Mäder, Geraldo; Nunes, Teonildes S; Queiroz, Luciano P; de Oliveira, Guilherme; Diniz-Filho, José Alexandre F; Bonatto, Sandro L; Freitas, Loreta B

    2016-08-01

    The Atlantic Forest is one of the most species-rich ecoregions in the world. The historical origins of this richness and the evolutionary processes that produced diversification and promoted speciation in this ecosystem remain poorly understood. In this context, focusing on Passiflora contracta, an endemic species from the Atlantic Forest distributed exclusively at sea level along forest edges, this study aimed to characterize the patterns of genetic variability and explore two hypotheses that attempt to explain the possible causes of the genetic diversity in this region: the refuge and riverine barrier theories. We employed Bayesian methods combined with niche modeling to identify genetically homogeneous groups, to determine the diversification age, and identify long-term climate stability areas to species survival. The analyses were performed using molecular markers from nuclear and plastid genomes, with samples collected throughout the entire geographic distribution of the species, and comparisons with congeners species. The results indicated that populations were genetically structured and provided evidence of demographic stability. The molecular markers indicated the existence of a clear structure and the presence of five homogeneous groups. Interestingly, the separation of the groups coincides with the geographical locations of local rivers, corroborating the hypothesis of rivers acting as barriers to gene flow in this species. The highest levels of genetic diversity and the areas identified as having long-term climate stability were found in the same region reported for other species as a possible refuge area during the climatic changes of the Quaternary. PMID:27188539

  19. Groundwater age, life expectancy and transit time distributions in advective dispersive systems; 2. Reservoir theory for sub-drainage basins

    NASA Astrophysics Data System (ADS)

    Cornaton, F.; Perrochet, P.

    2006-09-01

    Groundwater age and life expectancy probability density functions (pdf) have been defined, and solved in a general three-dimensional context by means of forward and backward advection-dispersion equations [Cornaton F, Perrochet P. Groundwater age, life expectancy and transit time distributions in advective-dispersive systems; 1. Generalized reservoir theory. Adv Water Res (xxxx)]. The discharge and recharge zones transit time pdfs were then derived by applying the reservoir theory (RT) to the global system, thus considering as ensemble the union of all inlet boundaries on one hand, and the union of all outlet boundaries on the other hand. The main advantages in using the RT to calculate the transit time pdf is that the outlet boundary geometry does not represent a computational limiting factor (e.g. outlets of small sizes), since the methodology is based on the integration over the entire domain of each age, or life expectancy, occurrence. In the present paper, we extend the applicability of the RT to sub-drainage basins of groundwater reservoirs by treating the reservoir flow systems as compartments which transfer the water fluxes to a particular discharge zone, and inside which mixing and dispersion processes can take place. Drainage basins are defined by the field of probability of exit at outlet. In this way, we make the RT applicable to each sub-drainage system of an aquifer of arbitrary complexity and configuration. The case of the well-head protection problem is taken as illustrative example, and sensitivity analysis of the effect of pore velocity variations on the simulated ages is carried out.

  20. Vibration analysis of rotating functionally graded Timoshenko microbeam based on modified couple stress theory under different temperature distributions

    NASA Astrophysics Data System (ADS)

    Ghadiri, Majid; Shafiei, Navvab

    2016-04-01

    In this study, thermal vibration of rotary functionally graded Timoshenko microbeam has been analyzed based on modified couple stress theory considering temperature change in four types of temperature distribution on thermal environment. Material properties of FG microbeam are supposed to be temperature dependent and vary continuously along the thickness according to the power-law form. The axial forces are also included in the model as the thermal and true spatial variation due to the rotation. Governing equations and boundary conditions have been derived by employing Hamiltonian's principle. The differential quadrature method is employed to solve the governing equations for cantilever and propped cantilever boundary conditions. Validations are done by comparing available literatures and obtained results which indicate accuracy of applied method. Results represent effects of temperature changes, different boundary conditions, nondimensional angular velocity, length scale parameter, different boundary conditions, FG index and beam thickness on fundamental, second and third nondimensional frequencies. Results determine critical values of temperature changes and other essential parameters which can be applicable to design micromachines like micromotor and microturbine.

  1. Investigating short-range magnetism in strongly correlated materials via magnetic pair distribution function analysis and ab initio theory

    NASA Astrophysics Data System (ADS)

    Frandsen, Benjamin; Page, Katharine; Brunelli, Michela; Staunton, Julie; Billinge, Simon

    Short-range magnetic correlations are known to exist in a variety of strongly correlated electron systems, but our understanding of the role they play is challenged by the difficulty of experimentally probing such correlations. Magnetic pair distribution function (mPDF) analysis is a newly developed neutron total scattering method that can reveal short-range magnetic correlations directly in real space, and may therefore help ameliorate this difficulty. We present temperature-dependent mPDF measurements of the short-range magnetic correlations in the paramagnetic phase of antiferromagnetic MnO, an archetypal strongly correlated transition-metal oxide. We observe significant correlations on a ~1 nm length scale that differ substantially from the low-temperature long-range-ordered spin arrangement. With no free parameters, ab initio calculations using the self-interaction-corrected local spin density approximation of density functional theory quantitatively reproduce the magnetic correlations to a high degree of accuracy. These results yield valuable insight into the magnetic exchange in MnO and showcase the utility of the mPDF technique for studying magnetic properties of strongly correlated electron systems.

  2. Distributed Leadership: A Good Theory but What if Leaders Won't, Don't Know How, or Can't Lead?

    ERIC Educational Resources Information Center

    McKenzie, Kathryn Bell; Locke, Leslie Ann

    2014-01-01

    This article presents the results from an empirical qualitative study of the challenges faced by teacher leaders in their attempts to work directly with their colleagues to change instructional strategies and improve student success. Additionally, it offers a challenge to the utility of a naïvely espoused theory of distributed leadership, which…

  3. A hybrid framework of first principles molecular orbital calculations and a three-dimensional integral equation theory for molecular liquids: Multi-center molecular Ornstein–Zernike self-consistent field approach

    SciTech Connect

    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.

  4. A hybrid framework of first principles molecular orbital calculations and a three-dimensional integral equation theory for molecular liquids: Multi-center molecular Ornstein-Zernike self-consistent field approach

    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.

  5. A hybrid framework of first principles molecular orbital calculations and a three-dimensional integral equation theory for molecular liquids: multi-center molecular Ornstein-Zernike self-consistent field approach.

    PubMed

    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. PMID:26156461

  6. Evolution equation for the B-meson distribution amplitude in the heavy-quark effective theory in coordinate space

    SciTech Connect

    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.

  7. Evolution equation for the B-meson distribution amplitude in the heavy-quark effective theory in coordinate space

    NASA Astrophysics Data System (ADS)

    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 μ with smaller interquark separations zt (z≤1). This formula allows us to present rigorous calculation of the B-meson DA at the factorization scale ˜mbΛQCD for t less than ˜1GeV-1, using the recently obtained operator product expansion of the DA as the input at μ˜1GeV. We also derive the master formula, which reexpresses the integrals of the DA at μ˜mbΛQCD for the factorization formula by the compact integrals of the DA at μ˜1GeV.

  8. Fast Computation of Solvation Free Energies with Molecular Density Functional Theory: Thermodynamic-Ensemble Partial Molar Volume Corrections.

    PubMed

    Sergiievskyi, Volodymyr P; Jeanmairet, Guillaume; Levesque, Maximilien; Borgis, Daniel

    2014-06-01

    Molecular density functional theory (MDFT) offers an efficient implicit-solvent method to estimate molecule solvation free-energies, whereas conserving a fully molecular representation of the solvent. Even within a second-order approximation for the free-energy functional, the so-called homogeneous reference fluid approximation, we show that the hydration free-energies computed for a data set of 500 organic compounds are of similar quality as those obtained from molecular dynamics free-energy perturbation simulations, with a computer cost reduced by 2-3 orders of magnitude. This requires to introduce the proper partial volume correction to transform the results from the grand canonical to the isobaric-isotherm ensemble that is pertinent to experiments. We show that this correction can be extended to 3D-RISM calculations, giving a sound theoretical justification to empirical partial molar volume corrections that have been proposed recently. PMID:26273876

  9. Comparison of theory and in situ observations for electron and ion distributions in the near wake of the Explorer 31 and AE-C satellites

    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.

  10. A Meta-Analysis of Distributed Leadership from 2002 to 2013: Theory Development, Empirical Evidence and Future Research Focus

    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…

  11. Orientation-dependent effects in Oort's theory of comet origin. II - Anisotropies in the distribution of long-period comet orbits.

    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.

  12. Fractional representation theory - Robustness results with applications to finite dimensional control of a class of linear distributed systems

    NASA Technical Reports Server (NTRS)

    Nett, C. N.; Jacobson, C. A.; Balas, M. J.

    1983-01-01

    This paper reviews and extends the fractional representation theory. In particular, new and powerful robustness results are presented. This new theory is utilized to develop a preliminary design methodology for finite dimensional control of a class of linear evolution equations on a Banach space. The design is for stability in an input-output sense, but particular attention is paid to internal stability as well.

  13. A Matter of Low Self-Control? Exploring Differences Between Child Pornography Possessors and Child Pornography Producers/Distributers Using Self-Control Theory.

    PubMed

    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. PMID:25394664

  14. The Development of a Distributive Interactive Computing Model in Consumer Economics, Utilizing Jerome S. Bruner's Theory of Instruction.

    ERIC Educational Resources Information Center

    Morrison, James L.

    A computerized delivery system in consumer economics developed at the University of Delaware uses the PLATO system to provide a basis for analyzing consumer behavior in the marketplace. The 16 sequential lessons, part of the Consumer in the Marketplace Series (CMS), demonstrate consumer economic theory in layman's terms and are structured to focus…

  15. Fission fragment charge and mass distributions in 239Pu(n, f ) in the adiabatic nuclear energy density functional theory

    DOE PAGESBeta

    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.

  16. Effect of a Nonplanar Melt-Solid Interface on Lateral Compositional Distribution during Unidirectional Solidification of a Binary Alloy with a Constant Growth Velocity V. Part 1; Theory

    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.

  17. Effect of a Nonplanar Melt-Solid Interface On Lateral Compositional Distribution During Unidirectional Solidification of a Binary Alloy with a Constant Growth Velocity V. Pt. 1; Theory

    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.

  18. A useful relationship between epidemiology and queueing theory: the distribution of the number of infectives at the moment of the first detection.

    PubMed

    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. PMID:19233215

  19. The theory research of multi-user quantum access network with Measurement Device Independent quantum key distribution

    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.

  20. Optimal sampling theory and population modelling - Application to determination of the influence of the microgravity environment on drug distribution and elimination

    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.

  1. The Mean Distance to the nth Neighbour in a Uniform Distribution of Random Points: An Application of Probability Theory

    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…

  2. The Theory of Distributed Practice as Related to Acquisition of Psychomotor Skills by Adolescents in a Selected Curricular Field.

    ERIC Educational Resources Information Center

    Drake, James Bob

    1981-01-01

    From results on the tensile strength and nick-break average jury evaluations test, it was concluded that with the same total practice time, different distributions of welding practice time intervals (15, 30, and 45 minutes) influence the quality of butt welds made by ninth-grade vocational agriculture students. (Author/SJL)

  3. Calculation of flow distribution in large radius ratio stages of axial flow turbines and comparison of theory and experiment

    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.

  4. Using New Theory and Experimental Methods to Understand the Relative Controls of Storage, Antecedent Conditions and Precipitation Intensity on Transit Time Distributions through a Sloping Soil Lysimeter

    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

  5. Rotational distributions following van der Waals molecule dissociation: Comparison between experiment and theory for benzene-Ar

    NASA Astrophysics Data System (ADS)

    Sampson, Rebecca K.; Bellm, Susan M.; McCaffery, Anthony J.; Lawrance, Warren D.

    2005-02-01

    The translational energy release distribution for dissociation of benzene-Ar has been measured and, in combination with the 610 rotational contour of the benzene product observed in emission, used to determine the rotational J,K distribution of 00 benzene products formed during dissociation from 61¯. Significant angular momentum is transferred to benzene on dissociation. The 00 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°. 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.

  6. Direct Comparisons among Fast Off-Lattice Monte Carlo Simulations, Integral Equation Theories, and Gaussian Fluctuation Theory for Disordered Symmetric Diblock Copolymers

    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).

  7. Theory and practice of perceptual video processing in broadcast encoders for cable, IPTV, satellite, and internet distribution

    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.

  8. The theory of propellers IV : thrust, energy, and efficiency formulas for single and dual rotating propellers with ideal circulation distribution

    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.

  9. Spatial distribution of protons at high and low altitudes in the radiation belts. Comparison of theory and experiment

    SciTech Connect

    Panasyuk, M.I.; Reizman, S.Y.; Sosnovets, E.N.

    1986-05-01

    A comparative analysis of experimental data on the spatial distributions of protons with energies (E) greater than 0.1 MeV at high and low latitudes, which were obtained on the Molniya-1, Kosmos-900, Elektron, and 1964-45A satellites, is carried out. As a result of the comparison of the experimental data relating to the measurements of protons with E - 0.2 MeV with the calculation including radial drift of particles under the action of electric and magnetic field fluctuations, it is shown that radial diffusion with a diffusion coefficient independent of geomagnetic latitude is the primary mechanism shaping the spatial distributions of protons at geomagnetic latitudes up to ..lambda.. approx. = 40/sup 0/. The results of the experiments and the calculations agree under the assumption of both magnetic and electric diffusion, but the latter case requires the inclusion of the model of a spatially inhomogeneous convection electric field. At ..lambda.. greater than or equal to 50/sup 0/ pitchangle scattering makes the primary contribution to the shaping of the spatial structure of the protons at low altitudes. A value of 2 less than or equal to n less than or equal to 4 is obtained for the exponent of the slope of the radial distribution of cold electrons N /sub e/ (r)..cap alpha.. /sup -n/ at 2 less than or equal to L less than or equal to 4.

  10. Random matrix theory of singular values of rectangular complex matrices I: Exact formula of one-body distribution function in fixed-trace ensemble

    SciTech Connect

    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.

  11. Coarse-grained theory to predict the concentration distribution of red blood cells in wall-bounded Couette flow at zero Reynolds number

    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.

  12. Characterization of the Tail of the Distribution of Earthquake Magnitudes by Combining the GEV and GPD Descriptions of Extreme Value Theory

    NASA Astrophysics Data System (ADS)

    Pisarenko, V. F.; Sornette, A.; Sornette, D.; Rodkin, M. V.

    2014-08-01

    The present work is a continuation and improvement of the method suggested in P isarenko et al. (Pure Appl Geophys 165:1-42, 2008) for the statistical estimation of the tail of the distribution of earthquake sizes. The chief innovation is to combine the two main limit theorems of Extreme Value Theory (EVT) that allow us to derive the distribution of T-maxima (maximum magnitude occurring in sequential time intervals of duration T) for arbitrary T. This distribution enables one to derive any desired statistical characteristic of the future T-maximum. We propose a method for the estimation of the unknown parameters involved in the two limit theorems corresponding to the Generalized Extreme Value distribution (GEV) and to the Generalized Pareto Distribution (GPD). We establish the direct relations between the parameters of these distributions, which permit to evaluate the distribution of the T-maxima for arbitrary T. The duality between the GEV and GPD provides a new way to check the consistency of the estimation of the tail characteristics of the distribution of earthquake magnitudes for earthquake occurring over an arbitrary time interval. We develop several procedures and check points to decrease the scatter of the estimates and to verify their consistency. We test our full procedure on the global Harvard catalog (1977-2006) and on the Fennoscandia catalog (1900-2005). For the global catalog, we obtain the following estimates: = 9.53 ± 0.52 and = 9.21 ± 0.20. For Fennoscandia, we obtain = 5.76 ± 0.165 and = 5.44 ± 0.073. The estimates of all related parameters for the GEV and GPD, including the most important form parameter, are also provided. We demonstrate again the absence of robustness of the generally accepted parameter characterizing the tail of the magnitude-frequency law, the maximum possible magnitude M max, and study the more stable parameter Q T ( q), defined as the q-quantile of the distribution of T-maxima on a future interval of duration T.

  13. Analytical theory of a current sheet formed between the magnetized and nonmagnetized plasmas with arbitrary energy distribution of particles

    NASA Astrophysics Data System (ADS)

    Martyanov, Vladimir; Kocharovsky, Vladimir; Kocharovsky, Vitaly

    We present analytical description of a self-consistent stationary boundary layer formed between the magnetized and nonmagnetized collisionless plasmas with arbitrary energy distribution of particles. Various spatial profiles of the current and respective particle distributions in the neutral current sheets are found on the basis of the self-consistency equation of the Grad-Shafranov type, which takes into account a homogeneous external magnetic field. The solutions are obtained due to development of the method of invariants of particle motion (Astron. Lett. 36, 396 (2010)) and provide, for the first time, a detailed description of various transition domains in the magnetospheres of stars and planets, in particular, boundary regions formed by an interaction of a solar wind with an interstellar medium or Earth magnetosphere. We restrict ourselves to the shearless magnetic field configurations and consider four special dependencies of particle distribution function on momentum parallel to current direction, which make it possible to detail the relations between the magnetic field profile, plasma density, and particle anisotropy gradient, including both thin and thick (with respect to a particle gyroradius) layers. Special attention is paid to the cases of an utmost sharp boundary between the magnetized and nonmagnetized plasmas and to the cases where there are sections of a boundary current sheet with magnetic field energy density exceeding kinetic energy density of plasma particles. The kinetic instabilities and reconnection phenomena are also discussed, especially the ones related to the Weibel instability in the weakly magnetized parts of the boundary layer. These analytical results are applied to the analysis of the spacecraft observations of the magnetized-nonmagnetized boundaries in cosmic plasma.

  14. Toward the theory of stochastic condensation in clouds. Part 2: Analytical solutions of the gamma-distribution type

    SciTech Connect

    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.

  15. Two-state theory of binned photon statistics for a large class of waiting time distributions and its application to quantum dot blinking

    SciTech Connect

    Volkán-Kacsó, Sándor

    2014-06-14

    A theoretical method is proposed for the calculation of the photon counting probability distribution during a bin time. Two-state fluorescence and steady excitation are assumed. A key feature is a kinetic scheme that allows for an extensive class of stochastic waiting time distribution functions, including power laws, expanded as a sum of weighted decaying exponentials. The solution is analytic in certain conditions, and an exact and simple expression is found for the integral contribution of “bright” and “dark” states. As an application for power law kinetics, theoretical results are compared with experimental intensity histograms from a number of blinking CdSe/ZnS quantum dots. The histograms are consistent with distributions of intensity states around a “bright” and a “dark” maximum. A gap of states is also revealed in the more-or-less flat inter-peak region. The slope and to some extent the flatness of the inter-peak feature are found to be sensitive to the power-law exponents. Possible models consistent with these findings are discussed, such as the combination of multiple charging and fluctuating non-radiative channels or the multiple recombination center model. A fitting of the latter to experiment provides constraints on the interaction parameter between the recombination centers. Further extensions and applications of the photon counting theory are also discussed.

  16. Myocardial temperature distribution under cw Nd:YAG laser irradiation in in vitro and in vivo situations: theory and experiment

    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.

  17. The distributed-order fractional diffusion-wave equation of groundwater flow: Theory and application to pumping and slug tests

    NASA Astrophysics Data System (ADS)

    Su, Ninghu; Nelson, Paul N.; Connor, Sarah

    2015-10-01

    We present a distributed-order fractional diffusion-wave equation (dofDWE) to describe radial groundwater flow to or from a well, and three sets of solutions of the dofDWE for flow from a well for aquifer tests: one for pumping tests, and two for slug tests. The dofDWE is featured by two temporal orders of fractional derivatives, β1 and β2, which characterise small and large pores, respectively. By fitting the approximate solutions of the dofDWE to data from slug tests in the field, we determined the effective saturated hydraulic conductivity, Ke, transmissivity, Tf, and the order of fractional derivatives, β2 in one test and β2 and β1 in the second test. We found that the patterns of groundwater flow from a well during the slug tests at this site belong to the class of sub-diffusion with β2 < 1 and β1 < 1 using both the short-time and large-time solutions. We introduce the concept of the critical time to link Ke as a function of β2 and β1. The importance of the orders of fractional derivatives is obvious in the approximate solutions: for short time slug tests only the parameter β2 for flow in large pores is present while for long time slug tests the parameters β2 and β1 are present indicating both large and small pores are functioning.

  18. Effect of charge distribution over a chlorophyll dimer on the redox potential of P680 in photosystem II as studied by density functional theory calculations.

    PubMed

    Takahashi, Ryouta; Hasegawa, Koji; Noguchi, Takumi

    2008-06-17

    The effect of charge distribution over a chlorophyll dimer on the redox potential of P680 in photosystem II was studied by density functional theory calculations using the P680 coordinates in the X-ray structure. From the calculated ionization potentials of the dimer and the monomeric constituents, the decrease in the redox potential by charge delocalization over the dimer was estimated to be approximately 140 mV. Such charge delocalization was previously observed in the isolated D1-D2-Cyt b 559 complexes, whereas the charge was primarily localized on P D1 in the core complexes. The calculated potential decrease of approximately 140 mV can explain the inhibition of Y Z oxidation in the former complexes and in turn implies that the charge localization on P D1 upon formation of the core complex increases the P680 potential to the level necessary for water oxidation. PMID:18500822

  19. Sequence and conformation effects on ionization potential and charge distribution of homo-nucleobase stacks using M06-2X hybrid density functional theory calculations.

    PubMed

    Rooman, Marianne; Wintjens, René

    2014-04-01

    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

  20. The ideal of equal health revisited: definitions and measures of inequity in health should be better integrated with theories of distributive justice.

    PubMed

    Norheim, Ole Frithjof; Asada, Yukiko

    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

  1. Sequence and conformation effects on ionization potential and charge distribution of homo-nucleobase stacks using M06-2X hybrid density functional theory calculations

    PubMed Central

    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

  2. The ideal of equal health revisited: definitions and measures of inequity in health should be better integrated with theories of distributive justice

    PubMed Central

    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

  3. Theory and computation of non-RRKM lifetime distributions and rates in chemical systems with three or more degrees of freedom

    NASA Astrophysics Data System (ADS)

    Gabern, Frederic; Koon, Wang S.; Marsden, Jerrold E.; Ross, Shane D.

    2005-11-01

    The computation, starting from basic principles, of chemical reaction rates in realistic systems (with three or more degrees of freedom) has been a longstanding goal of the chemistry community. Our current work, which merges tube dynamics with Monte Carlo methods provides some key theoretical and computational tools for achieving this goal. We use basic tools of dynamical systems theory, merging the ideas of Koon et al. [W.S. Koon, M.W. Lo, J.E. Marsden, S.D. Ross, Heteroclinic connections between periodic orbits and resonance transitions in celestial mechanics, Chaos 10 (2000) 427-469.] and De Leon et al. [N. De Leon, M.A. Mehta, R.Q. Topper, Cylindrical manifolds in phase space as mediators of chemical reaction dynamics and kinetics. I. Theory, J. Chem. Phys. 94 (1991) 8310-8328.], particularly the use of invariant manifold tubes that mediate the reaction, into a tool for the computation of lifetime distributions and rates of chemical reactions and scattering phenomena, even in systems that exhibit non-statistical behavior. Previously, the main problem with the application of tube dynamics has been with the computation of volumes in phase spaces of high dimension. The present work provides a starting point for overcoming this hurdle with some new ideas and implements them numerically. Specifically, an algorithm that uses tube dynamics to provide the initial bounding box for a Monte Carlo volume determination is used. The combination of a fine scale method for determining the phase space structure (invariant manifold theory) with statistical methods for volume computations (Monte Carlo) is the main contribution of this paper. The methodology is applied here to a three degree of freedom model problem and may be useful for higher degree of freedom systems as well.

  4. Control of dissolved Al distributions in marine sediments by clay reconstitution reactions: Experimental evidence leading to a unified theory

    NASA Astrophysics Data System (ADS)

    Mackin, James E.

    1986-02-01

    A set of sediment "resuspension" experiments was designed to test various aspects of previously hypothesized clay reconstitution reactions in nearshore sediments. Aliquots of wet sediment of approximately equal weight from Flax Pond, Long Island Sound were suspended in stirred and aerated, high salinity solutions having variable adjusted initial dissolved Si concentrations but otherwise nearly identical properties. Dissolved Al and Si and the water pH were monitored over the course of three days. Dissolved Si was removed from solution in the high initial Si (325 and 650 μM) containers, while little change in Si concentration was observed in a "blank" and 0 Si-spike container. Short-term dissolved Al production in the experiments suggests that clay dissolution is important in these sediments. Long-term dissolved Al behavior agrees fairly well with quantitative predictions based upon previous studies of nearshore sediments, where authigenic clays were believed to cause observed inverse relationships between dissolved Al and Si. The unambiguous results give strong evidence that inverse Al-Si relations in dissolved Fe-poor sediments are a direct result of mineral precipitation, rather than being due to some fortuitous combination of unrelated reactions affecting Al and Si. The Si/Al composition of authigenic clay precipitates in marine sediments probably varies directly with the dissolved Si content of contacting waters. This indicates that a combination of "weathering" and "reverse weathering" of minerals may affect Si distributions, and provides a theoretical link between these two sets of previously suggested mechanisms for clay reconstitution in sediments.

  5. Angular and Linear Velocity Estimation for a Re-Entry Vehicle Using Six Distributed Accelerometers: Theory, Simulation and Feasibility

    SciTech Connect

    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

  6. Generalized Courant-Snyder theory and Kapchinskij-Vladimirskij distribution for high-intensity beams in a coupled transverse focusing lattice

    SciTech Connect

    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.

  7. Generalized Courant-Snyder Theory and Kapchinskij-Vladimirskij Distribution For High-intensity Beams In A Coupled Transverse Focusing Lattice

    SciTech Connect

    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.

  8. On the distribution of DNA translocation times in solid-state nanopores: an analysis using Schrödinger's first-passage-time theory.

    PubMed

    Ling, Daniel Y; Ling, Xinsheng Sean

    2013-09-18

    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. PMID:23963318

  9. Variational theory of complex rays applied to shell structures: in-plane inertia, quasi-symmetric ray distribution, and orthotropic materials

    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.

  10. Study of scattering from a sphere with an eccentrically located spherical inclusion by generalized Lorenz-Mie theory: internal and external field distribution.

    PubMed

    Wang, J J; Gouesbet, G; Han, Y P; Gréhan, G

    2011-01-01

    Based on the recent results in the generalized Lorenz-Mie theory, solutions for scattering problems of a sphere with an eccentrically located spherical inclusion illuminated by an arbitrary shaped electromagnetic beam in an arbitrary orientation are obtained. Particular attention is paid to the description and application of an arbitrary shaped beam in an arbitrary orientation to the scattering problem under study. The theoretical formalism is implemented in a homemade computer program written in FORTRAN. Numerical results concerning spatial distributions of both internal and external fields are displayed in different formats in order to properly display exemplifying results. More specifically, as an example, we consider the case of a focused fundamental Gaussian beam (TEM(00) mode) illuminating a glass sphere (having a real refractive index equal to 1.50) with an eccentrically located spherical water inclusion (having a real refractive index equal to 1.33). Displayed results are for various parameters of the incident electromagnetic beam (incident orientation, beam waist radius, location of the beam waist center) and of the scatterer system (location of the inclusion inside the host sphere and relative diameter of the inclusion to the host sphere). PMID:21200408

  11. a Study of Liquid - of Atomization Droplet Size Velocity and Temperature Distribution via Information Theory Spray Interaction with Ambient Air Motion.

    NASA Astrophysics Data System (ADS)

    Li, Xianguo

    Linear temporal instability analysis of a moving thin viscous liquid sheet of uniform thickness in an inviscid gas medium shows that surface tension always opposes, while surrounding gas and relative velocity between the sheet and gas favour the onset and development of instability. For gas Weber number smaller than the density ratio of gas to liquid, liquid viscosity enhances instability; If gas Weber number is slightly larger, aerodynamic and viscosity -induced instabilities interact with each other, displaying complicated effects of viscosity via Ohnesorge number; For much larger values of gas Weber numbers, aerodynamic instability dominates, liquid viscosity reduces disturbance growth rate and increases the dominant wavelength. Droplet probability distribution function (PDF) in sprays is formulated through information theory without resorting to the details of atomization processes. The derived analytical droplet size PDF is Nukiyama-Tanasawa type if conservation of mass is considered alone. If conservation of mass, momentum and energy is all taken into account, the joint droplet size and velocity PDF depends on Weber number, and compares favourably with measurements. Droplet velocity PDF is truncated Gaussian for any specific droplet size. Mean velocity approaches a constant value and velocity variance decreases as droplet size increases. Mean droplet diameters calculated agree well with observations. The computation indicates that atomization efficiency is very low, usually less than 1%. Droplet size, velocity and temperature PDF in sprays under combusting environment has also been derived. Effects of combustion on PDF occur mainly through the heat transferred into liquid sheet prior to its breakup. Experimental studies identify three modes of spray behaviours due to its interaction with various annular air flows, and show that bluff-body type of combustor has ability and easement to control aerodynamically spray angle, shape and droplet trajectories. It is

  12. Analysis of K+/Na+ selectivity of KcsA potassium channel with reference interaction site model theory

    NASA Astrophysics Data System (ADS)

    Cui, Qizhi; Smith, Vedene H., Jr.

    2005-01-01

    As a preliminary approach, we have successfully analysed K+/Na+ selectivity of the KcsA potassium channel for the most selective ion occupancy state (1010) at the atomic level by using the reference interaction site model (RISM) integral equation theory [Q. Cui, V.H. Smith, Chem. Phys. Lett.365, 110 (2002)]. With similar methods, in this paper, we analyse seven other most relevant ion occupancy states: (0101), (0110), (1001), (1000), (0100), (0010) and (0001). By analysing all the most relevant states, we are able to characterize some dynamic properties of the systems. More detailed solvation structures of the selectivity filter are presented and more solvation energetic data are obtained and compared with the available molecular dynamics simulation data. We predict consistent results with the simulations in that ions are best dehydrated at binding site 2. For ion occupancy states of most interest, we obtain good relative solvation free energies in comparison with the simulation data. The results in this paper further support the conclusion in our previous paper that the selectivity filter favours K+ over Na+ from the point of view of solvation.

  13. Supramolecular Interactions in Secondary Plant Cell Walls: Effect of Lignin Chemical Composition Revealed with the Molecular Theory of Solvation.

    PubMed

    Silveira, Rodrigo L; Stoyanov, Stanislav R; Gusarov, Sergey; Skaf, Munir S; Kovalenko, Andriy

    2015-01-01

    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. PMID:26263115

  14. LIKELIHOOD RATIO TESTS OF HYPOTHESES ON MULTIVARIATE POPULATIONS, VOLUME 1, DISTRIBUTION THEORY--STATISTICAL MODELS FOR THE EVALUATION AND INTERPRETATION OF EDUCATIONAL CRITERIA, PART 4.

    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)

  15. Program for standard statistical distributions

    NASA Technical Reports Server (NTRS)

    Falls, L. W.

    1972-01-01

    Development of procedure to describe frequency distributions involved in statistical theory is discussed. Representation of frequency distributions by first order differential equation is presented. Classification of various types of distributions based on Pearson parameters is analyzed.

  16. CIRCE2/DEKGEN2: A software package for facilitated optical analysis of 3-D distributed solar energy concentrators. Theory and user manual

    SciTech Connect

    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.

  17. Communication: Direct comparison between theory and experiment for correlated angular and product-state distributions of the ground-state and stretching-excited O(3P) + CH4 reactions

    NASA Astrophysics Data System (ADS)

    Czakó, Gábor

    2014-06-01

    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(3P) + 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.

  18. Calculation of composition distribution of ultrafine ion-H2O-H2SO4 clusters using a modified binary ion nucleation theory

    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.

  19. Extension of the diffusion controlled electron transfer theory for intermittent fluorescence of quantum dots: inclusion of biexcitons and the difference of "on" and "off" time distributions.

    PubMed

    Zhu, Zhaoyan; Marcus, R A

    2014-12-21

    The equations for the diffusion controlled electron transfer (DCET) theory of quantum dot blinking are extended to include biexcitons. In contrast to excitons, which undego resonant light to dark transitions, the biexcitons, having a much larger total energy, undergo a Fermi's Golden rule type transfer (many acceptance states). The latter immediately gives rise to an exponential tail for the light state, and it is explained why the dark state power law behavior is unaffected. Results are given for both continuous and pulsed excitation. The typical -3/2 power law for the light state at low light intensities, and for the dark state at all intensities, as well as dependence of the exponential tail on the square of the light intensity, and a decrease of the power in the power law for the light state from -3/2 to less negative values with increasing light intensity are all consistent with the theory. The desirability of measuring the dependence of the spectral diffusion coefficient on light intensity at room temperature as a test of several aspects of the theory is noted. PMID:24801196

  20. String Theory and Gauge Theories

    SciTech Connect

    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.

  1. Uranyl Solvation by a Three-Dimensional Reference Interaction Site Model.

    PubMed

    Matveev, Alexei; Li, Bo; Rösch, Notker

    2015-08-13

    We report an implementation of the three-dimensional reference interaction site model (3D RISM) that in particular addresses the treatment of the long-range Coulomb field of charged species, represented by point charges and/or a distributed charge density. A comparison of 1D and 3D results for atomic ions demonstrates a reasonable accuracy, even for a moderate size of the unit cell and a moderate grid resolution. In an application to uranyl complexes with 4-6 explicit aqua ligands and an implicit bulk solvent modeled by RISM, we show that the 3D technique is not susceptible to the deficiencies of the 1D technique exposed in our previous work [Li, Matveev, Krüger, Rösch, Comp. Theor. Chem. 2015, 1051, 151]. The 3D method eliminates the artificial superposition of explicit aqua ligands and the RISM medium and predicts essentially the same values for uranyl and uranyl-water bond lengths as a state-of-the-art polarizable continuum model. With the first solvation shell treated explicitly, the observables are nearly independent of the order of the closure relationship used when solving the set of integral equations for the various distribution functions. Furthermore, we calculated the activation barrier of water exchange with a hybrid approach that combines the 3D RISM model for the bulk aqueous solvent and a quantum mechanical description (at the level of electronic density functional theory) of uranyl interacting with explicitly represented water molecules. The calculated result agrees very well with experiment and the best theoretical estimates. PMID:26167741

  2. Accuracy of temperature-derivative of radial distribution function calculated under approximations in Ornstein-Zernike theory for one-component Lennard-Jones fluid

    NASA Astrophysics Data System (ADS)

    Miyata, Tatsuhiko; Miyazaki, Sanae

    2016-08-01

    The accuracy of the temperature derivative of radial distribution function obtained under hypernetted chain (HNC), Kovalenko-Hirata (KH), Percus-Yevick (PY) and Verlet-modified (VM) closure approximations is examined for one-component Lennard-Jones fluid. As relevant thermodynamic quantities, constant-volume heat capacity and thermal pressure coefficient are investigated in terms of their accuracy under the above four approximations. It is found that HNC and KH closures overestimate these quantities, whereas PY closure tends to underestimate them. VM closure predicts rather accurately the quantities. A significant cancellation is observed along the integration for the above quantities under HNC and KH closures, especially at high density state.

  3. Signatures of the non-Maxwellian κ-distributions in optically thin line spectra. I. Theory and synthetic Fe IX-XIII spectra

    NASA Astrophysics Data System (ADS)

    Dudík, J.; Del Zanna, G.; Mason, H. E.; Dzifčáková, E.

    2014-10-01

    Aims: We investigate the possibility of diagnosing the degree of departure from the Maxwellian distribution using single-ion spectra originating in astrophysical plasmas in collisional ionization equilibrium. Methods: New atomic data for excitation of Fe ix - Fe xiii are integrated under the assumption of a κ-distribution of electron energies. Diagnostic methods using lines of a single ion formed at any wavelength are explored. Such methods minimize uncertainties from the ionization and recombination rates, as well as the possible presence of non-equilibrium ionization. Approximations to the collision strengths are also investigated. Results: The calculated intensities of most of the Fe ix - Fe xiii EUV lines show consistent behaviour with κ at constant temperature. Intensities of these lines decrease with κ, with the vast majority of ratios of strong lines showing little or no sensitivity to κ. Several of the line ratios, especially involving temperature-sensitive lines, show a sensitivity to κ that is of the order of several tens of per cent, or, in the case of Fe ix, up to a factor of two. Forbidden lines in the near-ultraviolet, visible, or infrared parts of the spectrum are an exception, with smaller intensity changes or even a reverse behaviour with κ. The most conspicuous example is the Fe x 6378.26 Å red line, whose intensity incerases with κ. This line is a potentially strong indicator of departures from the Maxwellian distribution. We find that it is possible to perform density diagnostics independently of κ, with many Fe xi, Fe xii, and Fe xiii line ratios showing strong density-sensitivity and negligible sensitivity to κ and temperature. We also tested different averaging of the collision strengths. It is found that averaging over 0.01 interval in log(E [ Ryd ]) is sufficient to produce accurate distribution-averaged collision strengths Υ(T,κ) at temperatures of the ion formation in ionization equilibrium. Appendices are available in

  4. Structural-acoustic model of a rectangular plate-cavity system with an attached distributed mass and internal sound source: Theory and experiment

    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.

  5. Two-component density functional theory within the projector augmented-wave approach: Accurate and self-consistent computations of positron lifetimes and momentum distributions

    NASA Astrophysics Data System (ADS)

    Wiktor, Julia; Jomard, Gérald; Torrent, Marc

    2015-09-01

    Many techniques have been developed in the past in order to compute positron lifetimes in materials from first principles. However, there is still a lack of a fast and accurate self-consistent scheme that could handle accurately the forces acting on the ions induced by the presence of the positron. We will show in this paper that we have reached this goal by developing the two-component density functional theory within the projector augmented-wave (PAW) method in the open-source code abinit. This tool offers the accuracy of the all-electron methods with the computational efficiency of the plane-wave ones. We can thus deal with supercells that contain few hundreds to thousands of atoms to study point defects as well as more extended defects clusters. Moreover, using the PAW basis set allows us to use techniques able to, for instance, treat strongly correlated systems or spin-orbit coupling, which are necessary to study heavy elements, such as the actinides or their compounds.

  6. The Normal-Theory and Asymptotic Distribution-Free (ADF) Covariance Matrix of Standardized Regression Coefficients: Theoretical Extensions and Finite Sample Behavior.

    PubMed

    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. PMID:24362970

  7. Toward Connecting Core-Collapse Supernova Theory with Observations: Nucleosynthetic Yields and Distribution of Elements in a 15 M⊙ Blue Supergiant Progenitor with SN 1987A Energetics

    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.

  8. An approach for generating trajectory-based dynamics which conserves the canonical distribution in the phase space formulation of quantum mechanics. I. Theories

    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.

  9. The Power of Micro Urban Structures, Theory of EEPGC - the Micro Urban Energy Distribution Model as a Planning Tool for Sustainable City Development

    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.

  10. An approach for generating trajectory-based dynamics which conserves the canonical distribution in the phase space formulation of quantum mechanics. I. Theories.

    PubMed

    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. PMID:21405150

  11. Exact relativistic kinetic theory of the full unstable spectrum of an electron-beam-plasma system with Maxwell-Jüttner distribution functions.

    PubMed

    Bret, A; Gremillet, L; Bénisti, D

    2010-03-01

    Following a recent Letter by Bret [Phys. Rev. Lett. 100, 205008 (2008)], we present a detailed report of the entire unstable k spectrum of a relativistic collisionless beam-plasma system within a fully kinetic framework. In contrast to a number of previously published studies, our linear analysis makes use of smooth momentum distribution functions of the Maxwell-Jüttner form. The three competing classes of instabilities, namely, two-stream, filamentation, and oblique modes, are dealt with in a unified manner, no approximation being made regarding the beam-plasma densities, temperatures, and drift energies. We investigate the hierarchy between the competing modes, paying particular attention to the relatively poorly known quasielectrostatic oblique modes in the regime where they govern the system. The properties of the fastest growing oblique modes are examined in terms of the system parameters and compared to those of the dominant two-stream and filamentation modes. PMID:20365877

  12. A scaling theory for the size distribution of emitted dust aerosols suggests climate models underestimate the size of the global dust cycle

    PubMed Central

    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

  13. Geostatistical Modeling of the Spatial Distribution of Soil Dioxins in the Vicinity of an Incinerator. 1. Theory and Application to Midland, Michigan

    PubMed Central

    Goovaerts, Pierre; Trinh, Hoa T.; Demond, Avery; Franzblau, Alfred; Garabrant, David; Gillespie, Brenda; Lepkowski, James; Adriaens, Peter

    2008-01-01

    Deposition of pollutants around point sources of contamination, such as incinerators, can display complex spatial patterns depending on prevailing weather conditions, the local topography and the characteristics of the source. Deterministic dispersion models often fail to capture the complexity observed in the field, resulting in uncertain predictions that might hamper subsequent decision-making, such as delineation of areas targeted for additional sampling or remediation. This paper describes a geostatistical simulation-based methodology that combines the detailed process-based modeling of atmospheric deposition from an incinerator with the probabilistic modeling of residual variability of field samples. The approach is used to delineate areas with high level of dioxin TEQDF-WHO98 (Toxic Equivalents) around an incinerator, accounting for 53 field data and the output of the EPA Industrial Source Complex (ISC3) dispersion model. The dispersion model explains 43.7% of the variance in soil TEQ data, while the regression residuals are spatially correlated with a range of 776 meters. One hundred realizations of soil TEQ values are simulated on a grid with a 50 meter spacing. The benefit of stochastic simulation over spatial interpolation is twofold: 1) maps of simulated point TEQ values can easily be aggregated to the geography that is the most relevant for decision making (e.g. census block, ZIP codes); and 2) the uncertainty at the larger scale is simply modeled by the empirical distribution of block-averaged simulated values. Incorporating the output of the atmospheric deposition model as spatial trend yields a more realistic prediction of the spatial distribution of TEQ value than lognormal kriging using only the field data, in particular in sparsely sampled areas away from the incinerator. The geostatistical model provided guidance for the study design (census block-based population sampling) of the University of Michigan Dioxin Exposure Study (UMDES), focused on

  14. Distributed Optimization

    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.

  15. Kinetic theory for charge-exchange spectroscopy: Effects of magnetic and electric fields on the distribution function after charge-exchange

    SciTech Connect

    Burrell, K. H.; Munoz Burgos, J. M.

    2012-07-15

    In plasmas equipped with neutral beam injection, excitation of atomic spectral lines via charge-exchange with neutral atoms is the basis of one of the standard plasma diagnostic techniques for ion density, temperature, and velocity. In order to properly interpret the spectroscopic results, one must consider the effects of the energy dependence of the charge-exchange cross-section as well as the motion of the ion after charge-exchange during the period when it is still in the excited state. This motion is affected by the electric and magnetic fields in the plasma. The present paper gives results for the velocity distribution function of the excited state ions and considers in detail the cross-section and ion motion effects on the post charge-exchange velocity. The expression for this velocity in terms of the charge-exchange cross-section and the pre charge-exchange velocity allows that latter velocity to be determined. The present paper is the first to consider the effect of the electric as well as the magnetic field and demonstrates that electric field and diamagnetic terms appear in the expression for the inferred velocity. The present formulation also leads to a novel technique for assessing the effect of the energy dependence of the charge-exchange cross-section on the inferred ion temperature.

  16. Near-Infrared Faint Galaxies in the Subaru Deep Field: Comparing the Theory with Observations for Galaxy Counts, Colors, and Size Distributions to K ~ 24.5

    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

  17. Theory on acoustic sources

    NASA Technical Reports Server (NTRS)

    Wright, S. E.

    1978-01-01

    A theory is described for the radiation emission emission from acoustic multipole sources. The sources can be stationary or moving at speeds including supersonic and experience stationary or moving disturbances. The effect of finite source distributions and disturbances is investigated as well as the manner in which they interact. Distinction is made between source distributions that responsed as a function of time and those that respond as a function of space.

  18. Packaging Theory.

    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…

  19. 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.

  20. Graph Theory

    SciTech Connect

    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.

  1. Confabulation Theory

    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.

  2. Toward a true spatial model evaluation in distributed hydrological modeling: Kappa statistics, Fuzzy theory, and EOF-analysis benchmarked by the human perception and evaluated against a modeling case study

    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.

  3. The bonding, charge distribution, spin ordering, optical, and elastic properties of four MAX phases Cr2AX (A = Al or Ge, X = C or N): From density functional theory study

    NASA Astrophysics Data System (ADS)

    Li, Neng; Mo, Yuxiang; Ching, Wai-Yim

    2013-11-01

    In this work, we assess a full spectrum of properties (chemical bonding, charge distribution, spin ordering, optical, and elastic properties) of Cr2AC (A = Al, Ge) and their hypothetical nitride counterparts Cr2AN (A = Al, Ge) based on density functional theory calculations. The calculated total energy values indicate that a variety of spin ordering of these four compounds depending on interlayer-interactions between M-A and M-X within the sublattice, which is supported by bonding analysis. MAX phase materials are discovered to possess exotic magnetic properties which indicates that these materials could serve as promising candidates for novel layered magnetic materials for various electronic and spintronic applications. Further analysis of optical properties for two polarization vectors of Cr2AX shows that the reflectivity is high in the visible-ultraviolet region up to ˜15 eV suggesting Cr2AX as a promising candidate for use as a coating material. The elastic coefficients (Cij) and bulk mechanical properties [bulk modulus (K), shear modulus (G), Young's modulus (E), Poisson's ratio (η), and Pugh ratio (G/K)] of these four Cr2AX compounds are also calculated and analyzed, which pave the way to predict or design new MAX phases that are less brittle or tougher by having a lower G/K value or higher η.

  4. The bonding, charge distribution, spin ordering, optical, and elastic properties of four MAX phases Cr{sub 2}AX (A = Al or Ge, X = C or N): From density functional theory study

    SciTech Connect

    Li, Neng; Mo, Yuxiang; Ching, Wai-Yim

    2013-11-14

    In this work, we assess a full spectrum of properties (chemical bonding, charge distribution, spin ordering, optical, and elastic properties) of Cr{sub 2}AC (A = Al, Ge) and their hypothetical nitride counterparts Cr{sub 2}AN (A = Al, Ge) based on density functional theory calculations. The calculated total energy values indicate that a variety of spin ordering of these four compounds depending on interlayer-interactions between M-A and M-X within the sublattice, which is supported by bonding analysis. MAX phase materials are discovered to possess exotic magnetic properties which indicates that these materials could serve as promising candidates for novel layered magnetic materials for various electronic and spintronic applications. Further analysis of optical properties for two polarization vectors of Cr{sub 2}AX shows that the reflectivity is high in the visible-ultraviolet region up to ∼15 eV suggesting Cr{sub 2}AX as a promising candidate for use as a coating material. The elastic coefficients (C{sub ij}) and bulk mechanical properties [bulk modulus (K), shear modulus (G), Young's modulus (E), Poisson's ratio (η), and Pugh ratio (G/K)] of these four Cr{sub 2}AX compounds are also calculated and analyzed, which pave the way to predict or design new MAX phases that are less brittle or tougher by having a lower G/K value or higher η.

  5. Sparse distributed memory

    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.

  6. Sparse distributed memory

    SciTech Connect

    Kanerva, P.

    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. 63 refs.

  7. Kinetic theory of vehicular traffic

    NASA Astrophysics Data System (ADS)

    Iannini, M. L. L.; Dickman, Ronald

    2016-02-01

    We review the kinetic theory of traffic proposed by Prigogine and Herman in which the Boltzmann equation is adapted to vehicular traffic. The kinetic equation and its solution are discussed, and a novel distribution of desired velocities that is more suitable for describing real traffic conditions is analyzed. We also study the stationary velocity distribution at the transition between individual and collective flow patterns. At this transition, the distribution splits into a smoothly varying regular part, in which vehicles have nonzero velocities, and a singular one, corresponding to stopped vehicles. Computational methods for obtaining the stationary velocity distribution and the full space-time evolution of the vehicular distribution are explained.

  8. Toward a Unified Theory of Similarity and Recognition.

    ERIC Educational Resources Information Center

    Ashby, F. Gregory; Perrin, Nancy A.

    1988-01-01

    Using general recognition theory, a new theory of similarity is developed, postulating that perceived similarity is determined by distributional overlap. This theory is related to existing theories of similarity. Three experiments using a total of 19 university students are presented, testing the empirical validity of the theory. (SLD)

  9. Theory and simulation of central force model potentials: Application to homonuclear diatomic molecules

    NASA Astrophysics Data System (ADS)

    Bresme, Fernando; Abascal, José L. F.; Lomba, Enrique

    1996-12-01

    Structure and thermodynamics of fluids made of particles that interact via a central force model potential are studied by means of Monte Carlo simulations and integral equation theories. The Hamiltonian has two terms, an intramolecular component represented by a harmonic oscillatorlike potential and an intermolecular interaction of the Lennard-Jones type. The potential does not fulfill the steric saturation condition so it leads to a polydisperse system. First, we investigate the association (clustering) and thermodynamic properties as a function of the potential parameters, such as the intramolecular potential depth, force constant, and bond length. It is shown that the atomic hypernetted chain (HNC) integral equation provides a correct description of the model as compared with simulation results. The calculation of the HNC pseudospinodal curve indicates that the stability boundaries between the vapor and liquid phases are strongly dependent on the bond length and suggests that there might be a direct gas-solid transition for certain elongations. On the other hand, we have assessed the ability of the model to describe the thermodynamics and structure of diatomic liquids such as N2 and halogens. To this end we have devised a procedure to model the intramolecular potential depth to reproduce the complete association limit (i.e., an average number of bonds per particle equal to one). This constraint is imposed on the Ornstein-Zernike integral equation in a straightforward numerical way. The structure of the resulting fluid is compared with results from molecular theories. An excellent agreement between the HNC results for the associating fluid and the reference interaction site model (RISM)-HNC computations for the atom-atom model of the same fluid is obtained. There is also a remarkable coincidence between the simulation results for the molecular and the associating liquids, despite the polydisperse character of the latter. The stability boundaries in the complete

  10. Multigrid solver for the reference interaction site model of molecular liquids theory.

    PubMed

    Sergiievskyi, Volodymyr P; Hackbusch, Wolfgang; Fedorov, Maxim V

    2011-07-15

    In this article, we propose a new multigrid-based algorithm for solving integral equations of the reference interactions site model (RISM). We also investigate the relationship between the parameters of the algorithm and the numerical accuracy of the hydration free energy calculations by RISM. For this purpose, we analyzed the performance of the method for several numerical tests with polar and nonpolar compounds. The results of this analysis provide some guidelines for choosing an optimal set of parameters to minimize computational expenses. We compared the performance of the proposed multigrid-based method with the one-grid Picard iteration and nested Picard iteration methods. We show that the proposed method is over 30 times faster than the one-grid iteration method, and in the high accuracy regime, it is almost seven times faster than the nested Picard iteration method. PMID:21455965

  11. String Theory

    NASA Astrophysics Data System (ADS)

    Susskind, Leonard

    2013-01-01

    After reviewing the original motivation for the formulation of string theory and what we learned from it, I discuss some of the implications of the holographic principle and of string dualities for the question of the building blocks of nature.

  12. Quantum Theory

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    A theory based on the premise that, on the microscopic scale, physical quantities have discrete, rather than a continuous range of, values. The theory was devised in the early part of the twentieth century to account for certain phenomena that could not be explained by classical physics. In 1900, the German physicist, Max Planck (1858-1947), was able precisely to describe the previously unexplaine...

  13. Predictive Game 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.

  14. 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)

  15. Effective theories of universal theories

    NASA Astrophysics Data System (ADS)

    Wells, James D.; Zhang, Zhengkang

    2016-01-01

    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. In the effective field theory (EFT) framework, the oblique parameters should not be associated with Wilson coefficients in a particular operator basis, unless restrictions have been imposed on the EFT so that it describes universal theories. 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, hf f , hV V vertices, 3 parameters for hV V vertices absent in the Standard Model, and 1 four-fermion coupling of order y f 2 . 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.

  16. Distributed processing; distributed functions?

    PubMed Central

    Fox, Peter T.; Friston, Karl J.

    2016-01-01

    After more than twenty years busily mapping the human brain, what have we learned from neuroimaging? This review (coda) considers this question from the point of view of structure–function relationships and the two cornerstones of functional neuroimaging; functional segregation and integration. Despite remarkable advances and insights into the brain’s functional architecture, the earliest and simplest challenge in human brain mapping remains unresolved: We do not have a principled way to map brain function onto its structure in a way that speaks directly to cognitive neuroscience. Having said this, there are distinct clues about how this might be done: First, there is a growing appreciation of the role of functional integration in the distributed nature of neuronal processing. Second, there is an emerging interest in data-driven cognitive ontologies, i.e., that are internally consistent with functional anatomy. We will focus this review on the growing momentum in the fields of functional connectivity and distributed brain responses and consider this in the light of meta-analyses that use very large data sets to disclose large-scale structure–function mappings in the human brain. PMID:22245638

  17. Elasticity theory

    NASA Astrophysics Data System (ADS)

    Moraru, Gheorghe; Mursa, Condrat

    2006-12-01

    In this book we present the basic concepts of the theory of elasticity: stress and deformation states (plane and three-dimensional) and generalized Hooke's law. We present a number of problems which have applications in strength analysis. The book includes a synthesis of the theory of elasticity and modern methods of applied mathematics. This book is designed for students, post graduate students and specialists in strength analysis. the book contains a number of appendixes which includes: elements of matrix-calculation, concepts of tensorial calculation, the Fourier transform, the notion of improper integrals,singular and hypersingular integrals, generalized functions, the Dirac Delta function

  18. Theory Queries.

    ERIC Educational Resources Information Center

    Moorman, Thomas

    1992-01-01

    Students experience the distinction between observable fact and scientific theory by taking a critical look at how spaghetti can be sucked up into the mouth. A demonstration shows that air is needed to suck up the spaghetti but that the scientific explanation is not as simple. (MDH)

  19. Control Theory.

    ERIC Educational Resources Information Center

    Toso, Robert B.

    2000-01-01

    Inspired by William Glasser's Reality Therapy ideas, Control Theory (CT) is a disciplinary approach that stresses people's ability to control only their own behavior, based on internal motivations to satisfy five basic needs. At one North Dakota high school, CT-trained teachers are the program's best recruiters. (MLH)

  20. Electroweak Theory

    NASA Astrophysics Data System (ADS)

    Paschos, E. A.

    2005-01-01

    The electroweak theory unifies two basic forces of nature: the weak force and electromagnetism. This book is a concise introduction to the structure of the electroweak theory and its applications. It describes the structure and properties of field theories with global and local symmetries, leading to the construction of the standard model. It describes the new particles and processes predicted by the theory, and compares them with experimental results. It also covers neutral currents, the properties of W and Z bosons, the properties of quarks and mesons containing heavy quarks, neutrino oscillations, CP-asymmetries in K, D, and B meson decays, and the search for Higgs particles. Each chapter contains problems, stemming from the long teaching experience of the author, to supplement the text. This will be of great interest to graduate students and researchers in elementary particle physics. Password protected solutions are available to lecturers at www.cambridge.org/9780521860987. Each chapter has an introduction highlighting its contents and giving a historical perspective. Chapters are cross-referenced, interrelating concepts and sections of the book. Contains 49 exercises

  1. 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.

  2. 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…

  3. 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.

  4. What makes distributed practice effective?

    PubMed Central

    Benjamin, Aaron S.; Tullis, Jonathan

    2010-01-01

    The advantages provided to memory by the distribution of multiple practice or study opportunities are among the most powerful effects in memory research. In this paper, we critically review the class of theories that presume contextual or encoding variability as the sole basis for the advantages of distributed practice, and recommend an alternative approach based on the idea that some study events remind learners of other study events. Encoding variability theory encounters serious challenges in two important phenomena that we review here: superadditivity and nonmonotonicity. The bottleneck in such theories lies in the assumption that mnemonic benefits arise from the increasing independence, rather than interdependence, of study opportunities. The reminding model accounts for many basic results in the literature on distributed practice, readily handles data that are problematic for encoding variability theories, including superadditivity and nonmonotonicity, and provides a unified theoretical framework for understanding the effects of repetition and the effects of associative relationships on memory. PMID:20580350

  5. Helicopter theory

    NASA Technical Reports Server (NTRS)

    Johnson, W.

    1980-01-01

    A comprehensive presentation is made of the engineering analysis methods used in the design, development and evaluation of helicopters. After an introduction covering the fundamentals of helicopter rotors, configuration and operation, rotary wing history, and the analytical notation used in the text, the following topics are discussed: (1) vertical flight, including momentum, blade element and vortex theories, induced power, vertical drag and ground effect; (2) forward flight, including in addition to momentum and vortex theory for this mode such phenomena as rotor flapping and its higher harmonics, tip loss and root cutout, compressibility and pitch-flap coupling; (3) hover and forward flight performance assessment; (4) helicopter rotor design; (5) rotary wing aerodynamics; (6) rotary wing structural dynamics, including flutter, flap-lag dynamics ground resonance and vibration and loads; (7) helicopter aeroelasticity; (8) stability and control (flying qualities); (9) stall; and (10) noise.

  6. MFIX documentation theory guide

    SciTech Connect

    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.

  7. Potential theory of radiation

    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.

  8. 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.

  9. Whole Trait Theory

    PubMed Central

    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

  10. 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.

  11. Density functional theory for Yukawa fluids

    NASA Astrophysics Data System (ADS)

    Hatlo, Marius M.; Banerjee, Priyanka; Forsman, Jan; Lue, Leo

    2012-08-01

    We develop an approximate field theory for particles interacting with a generalized Yukawa potential. This theory improves and extends a previous splitting field theory, originally developed for counterions around a fixed charge distribution. The resulting theory bridges between the second virial approximation, which is accurate at low particle densities, and the mean-field approximation, accurate at high densities. We apply this theory to charged, screened ions in bulk solution, modeled to interact with a Yukawa potential; the theory is able to accurately reproduce the thermodynamic properties of the system over a broad range of conditions. The theory is also applied to "dressed counterions," interacting with a screened electrostatic potential, contained between charged plates. It is found to work well from the weak coupling to the strong coupling limits. The theory is able to reproduce the counterion profiles and force curves for closed and open systems obtained from Monte Carlo simulations.

  12. Extension of Ostwald Ripening Theory

    NASA Technical Reports Server (NTRS)

    Baird, J.; Naumann, R.

    1985-01-01

    The objective is to develop models based on the mean field approximation of Ostwald ripening to describe the growth of second phase droplets or crystallites. The models will include time variations in nucleation rate, control of saturation through addition of solute, precipitating agents, changes in temperature, and various surface kinetic effects. Numerical integration schemes have been developed and tested against the asymptotic solution of Liftshitz, Slyozov and Wagner (LSW). A second attractor (in addition to the LSW distribution) has been found and, contrary to the LSW theory, the final distribution is dependent on the initial distribution. A series of microgravity experiments is being planned to test this and other results from this work.

  13. Theory of twisted nonuniformly heated bars

    NASA Technical Reports Server (NTRS)

    Shorr, B. F.

    1980-01-01

    Nonlineary distributed stresses in twisted nonuniformly heated bars of arbitrary cross section are calculated taking into account various elasticity parameters. The approximate theory is shown to be sufficiently general and accurate by comparison with experimental data.

  14. Wavelet theory and its applications

    SciTech Connect

    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.

  15. 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…

  16. Probing the Adsorption Behavior of 4,5-Diazafluoren-9-one and Its Schiff Base Derivatives on SIlver and Gold Nanosurfaces Using Raman Spectroscopy, Density Functional Theory and Potential Energy Distribution Calculations

    NASA Astrophysics Data System (ADS)

    McCoy, Rhonda Patrice

    4,5-Diazafluoren-9-one (DAFO) is an aromatic ketone synthesized by oxidizing 1,10-phenanthroline with potassium permanganate. In this present study, the Raman spectra of DAFO in the solid and solution states were recorded in the 100-2000 cm-1 spectral region using 1064, 633, 532, and 514 nm excitation sources. A normal mode analysis of DAFO was performed using density functional theory; the BLYP and B3LYP functionals, each with the 6-31G(d) and 6-311(d) basis sets were employed. The fundamental modes on the Raman spectrum of DAFO were assigned with the appropriate symmetry element using the BLYP functional and 6-31G(d) basis set. The vibrational modes were described and quantified by potential energy distribution calculations. The Raman frequencies for the solid and solution spectra were compared; the observed frequency shifts are attributed to hydrogen bonding or dipole-dipole interactions occurring between the solvent and DAFO ligand. To further assess solute-solvent interactions the UV-vis spectra of DAFO was obtained in hydrogen bonding, polar aprotic, and non-polar solvents. The fine structure of the band observed at lambda max becomes more resolved as solvent polarity decreases, therefore confirming solute-solvent interactions in polar solvents. A silver complex of DAFO was synthesized with the intent of understanding how coordination affected the Raman frequencies. The bands assigned to pyridine ring bending, nu(C=N), and nu(C=O) were shifted because of coordination. These shifts have been attributed to the molecule being perturbed because of coordination. Therefore, the Ag-DAFO complex was analyzed by X-Ray diffraction and the molecular geometries of the free and coordinated ligand were compared. The resolved crystalline structure revealed the silver ion coordinated DAFO using the lone pairs of electrons from the nitrogens in the pyridine ring. Analysis of the molecular geometry revealed the C=O bond increases in double bond character and the C5-C14 bond

  17. Partonic Transverse Momentum Distributions

    SciTech Connect

    Rossi, Patrizia

    2010-08-04

    In recent years parton distributions have been generalized to account also for transverse degrees of freedom and new sets of more general distributions, Transverse Momentum Dependent (TMD) parton distributions and fragmentation functions were introduced. Different experiments worldwide (HERMES, COMPASS, CLAS, JLab-Hall A) have measurements of TMDs in semi-inclusive DIS processes as one of their main focuses of research. TMD studies are also an important part of the present and future Drell-Yan experiments at RICH and JPARC and GSI, respectively, Studies of TMDs are also one of the main driving forces of the Jefferson Lab (JLab) 12 GeV upgrade project. Progress in phenomenology and theory is flourishing as well. In this talk an overview of the latest developments in studies of TMDs will be given and newly released results, ongoing activities, as well as planned near term and future measurements will be discussed.

  18. Aspects of Distributivity in Mandarin Chinese

    ERIC Educational Resources Information Center

    Tsai, Yaping

    2009-01-01

    One important task of any semantic theory of plurals is to account for the collective/distributive ambiguity. The goal of this dissertation is to achieve greater understanding of plurality and the collectivity/distributivity distinction from a cross-linguistic perspective by examining the phenomenon of distributivity in Mandarin Chinese. I show…

  19. Investigating School Leadership Practice: A Distributed Perspective.

    ERIC Educational Resources Information Center

    Spillane, James P.; Halverson, Richard; Diamond, John B.

    2001-01-01

    Argues for scholarship that investigates leadership practice; specifically, the practice of leading classroom instruction. Articulates a distributed perspective, grounded in activity theory and distributed cognition, to frame such investigations. Suggests that school leadership is best understood as a distributed practice stretched over the…

  20. Glucose transformation to 5-hydroxymethylfurfural in acidic ionic liquid: A quantum mechanical study.

    PubMed

    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. PMID:26453901

  1. Geometric approach to dislocation and disclination theory

    SciTech Connect

    Nesterov, A.I.; Ovchinnikov, S.G.

    1988-05-01

    Cartan structure equations are used to create a four-dimensional geometric description of dislocations in continuum theory. It is shown that the dislocation distribution is determined by the torsion tensor, while the disclination distribution is determined by the curvature tensor. An analogy to electrodynamics is offered.

  2. Distributed computing

    SciTech Connect

    Chambers, F.B.; Duce, D.A.; Jones, G.P.

    1984-01-01

    CONTENTS: The Dataflow Approach: Fundamentals of dataflow. Architecture and performance. Assembler level programming. High level dataflow programming. Declarative systems: Functional programming. Logic programming and prolog. The ''language first'' approach. Towards a successor to von Neumann. Loosely-coupled systems: Architectures. Communications. Distributed filestores. Mechanisms for distributed control. Distributed operating systems. Programming languages. Closely-coupled systems: Architecture. Programming languages. Run-time support. Development aids. Cyba-M. Polyproc. Modeling and verification: Using algebra for concurrency. Reasoning about concurrent systems. Each chapter includes references. Index.

  3. Modified Sigmund sputtering theory: isotopic puzzle

    NASA Astrophysics Data System (ADS)

    Zhang, Z. L.; Zhang, L.

    2005-05-01

    The theory of anisotropic sputtering proposed by Zhang [Z.L. Zhang, Phys. Rev. B 71 026101 (2005).] and [Z.L. Zhang and L. Zhang, Radiat. Eff. Defects Solids 159(5) 301 (2004).] has been generalized to sputtering of isotopic mixtures. The present theory (modified Sigmund theory) has been shown to fit numerous simulations and experimental measurements, including energy and angular distribution of sputtered atoms. In particular, the theory has successfully solved the isotope puzzle of sputtering induced by low energy and heavy ion bombardment.

  4. Distributed Intelligence.

    ERIC Educational Resources Information Center

    McLagan, Patricia A.

    2003-01-01

    Distributed intelligence occurs when people in an organization take responsibility for creating innovations, solving problems, and making decisions. Organizations that have it excel in their markets and the global environment. (Author/JOW)

  5. Vaginal drug distribution modeling.

    PubMed

    Katz, David F; Yuan, Andrew; Gao, Yajing

    2015-09-15

    This review presents and applies fundamental mass transport theory describing the diffusion and convection driven mass transport of drugs to the vaginal environment. It considers sources of variability in the predictions of the models. It illustrates use of model predictions of microbicide drug concentration distribution (pharmacokinetics) to gain insights about drug effectiveness in preventing HIV infection (pharmacodynamics). The modeling compares vaginal drug distributions after different gel dosage regimens, and it evaluates consequences of changes in gel viscosity due to aging. It compares vaginal mucosal concentration distributions of drugs delivered by gels vs. intravaginal rings. Finally, the modeling approach is used to compare vaginal drug distributions across species with differing vaginal dimensions. Deterministic models of drug mass transport into and throughout the vaginal environment can provide critical insights about the mechanisms and determinants of such transport. This knowledge, and the methodology that obtains it, can be applied and translated to multiple applications, involving the scientific underpinnings of vaginal drug distribution and the performance evaluation and design of products, and their dosage regimens, that achieve it. PMID:25933938

  6. 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.

  7. Sparse distributed memory

    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.

  8. Theory and Vocational Education.

    ERIC Educational Resources Information Center

    Swanson, Gordon I.

    1988-01-01

    The search for an explanation of day-to-day problems is the appropriate framework for describing theory. Theory and research have reciprocal relationships: Theory gives direction to research and research refines theory. Vocational education occurs in the context of many theoretical frames. Understanding this theory relatedness is important to…

  9. 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.

  10. String Theory and M-Theory

    NASA Astrophysics Data System (ADS)

    Becker, Katrin; Becker, Melanie; Schwarz, John H.

    String theory is one of the most exciting and challenging areas of modern theoretical physics. This book guides the reader from the basics of string theory to recent developments. It introduces the basics of perturbative string theory, world-sheet supersymmetry, space-time supersymmetry, conformal field theory and the heterotic string, before describing modern developments, including D-branes, string dualities and M-theory. It then covers string geometry and flux compactifications, applications to cosmology and particle physics, black holes in string theory and M-theory, and the microscopic origin of black-hole entropy. It concludes with Matrix theory, the AdS/CFT duality and its generalizations. This book is ideal for graduate students and researchers in modern string theory, and will make an excellent textbook for a one-year course on string theory. It contains over 120 exercises with solutions, and over 200 homework problems with solutions available on a password protected website for lecturers at www.cambridge.org/9780521860697. Comprehensive coverage of topics from basics of string theory to recent developments Ideal textbook for a one-year course in string theory Includes over 100 exercises with solutions Contains over 200 homework problems with solutions available to lecturers on-line

  11. 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)

  12. Theory of powdery rubber wear

    NASA Astrophysics Data System (ADS)

    Persson, B. N. J.

    2009-12-01

    Rubber wear typically involves the removal of small rubber particles from the rubber surface. On surfaces with not too sharp roughness, e.g. most road surfaces, this involves (slow) crack propagation. In this paper I shall present a theory of mild rubber wear. I shall derive the distribution of wear particle sizes Φ(D), which is in excellent agreement with experiment. I shall also show that the calculated wear rate is consistent with experimental data for tire tread block wear.

  13. Discussion: Confronting theory and experiment

    SciTech Connect

    Gallagher, Hugh; Hayato, Yoshinari; Sobczyk, Jan

    2015-05-15

    This session focused on the current status of neutrino event generators, in practical terms the tool through which ‘theory confronts experiment’. Comparisons of event generators, both in terms of input physics, and in terms of produced distributions, has been a staple of this conference series, and the activities in this area are summarized. In addition, we discuss the highest priorities for model development, discuss the changing needs of experimental users, and comment on challenges and needs for the road ahead.

  14. 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.

  15. Wealth distribution on complex networks

    NASA Astrophysics Data System (ADS)

    Ichinomiya, Takashi

    2012-12-01

    We study the wealth distribution of the Bouchaud-Mézard model on complex networks. It is known from numerical simulations that this distribution depends on the topology of the network; however, no one has succeeded in explaining it. Using “adiabatic” and “independent” assumptions along with the central-limit theorem, we derive equations that determine the probability distribution function. The results are compared to those of simulations for various networks. We find good agreement between our theory and the simulations, except for the case of Watts-Strogatz networks with a low rewiring rate due to the breakdown of independent assumption.

  16. A site-renormalized molecular fluid theory

    NASA Astrophysics Data System (ADS)

    Dyer, Kippi M.; Perkyns, John S.; Pettitt, B. Montgomery

    2007-11-01

    The orientation-dependent pair distribution function for molecular fluids on site-site potentials is expanded in a topological analog of the diagrammatically proper site-site theory of liquids [D. Chandler et al., Mol. Phys. 46, 1335 (1982)]. The resulting functions are then used to diagrammatically renormalize the molecular fluid theory. A result is that the diagrammatically proper interaction site model theory is shown to be a linearized, minimal angular basis set approximation to this site-renormalized molecular theory. This framework is used to propose a new, exact, and proper closure to the diagrammatically proper interaction site model theory. The resulting equation system contains a bridge function expansion in the proper site-site theory. In addition, the construction of the theory is such that the molecular pair distribution function, in full dimensionality, is intrinsic to the theory. Furthermore, the theory is equivalent to the molecular Ornstein-Zernike treatment of site-site molecules in the basis set expansion of Blum and Torruella [J. Chem. Phys. 56, 303 (1971)]. A significant formal result of the theory is the demonstration that certain classes of diagrams which would otherwise be considered improper in the interaction site model formalism are included in the angular expansion of molecular interactions. Numerical results for several apolar homonuclear models and an apolar heteronuclear model are shown to quantitatively improve upon those of reference interaction site model and our recent proper variant with respect to simulation. Significant numerical results are that the various thermodynamic quantities obey the exact symmetries and sum rules within numerical error for the different sites in the heteronuclear case, even for the low order approximation used in this work, and the theory is independent of the so-called auxiliary site problem common to previous site-site theories.

  17. Structure and thermodynamics of core-softened models for alcohols

    SciTech Connect

    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.

  18. A refined nonlinear theory of plates with transverse shear deformation

    NASA Technical Reports Server (NTRS)

    Reddy, J. N.

    1984-01-01

    A higher-order shear deformation theory of plates accounting for the von Karman strains is presented. The theory contains the same dependent unknowns as in the Hencky-Mindlin type first-order shear deformation theory and accounts for parabolic distribution of the transverse shear strains through the thickness of the plate. Exact solutions of simply supported plates are obtained using the linear theory and the results are compared with the exact solutions of three-dimensional elasticity theory, the first order shear deformation theory, and the classical plate theory. The present theory predicts the deflections, stresses, and frequencies more accurately when compared to the first-order theory and the classical plate theory.

  19. 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.

  20. Distributed Leadership.

    ERIC Educational Resources Information Center

    Lashway, Larry

    2003-01-01

    School-reform efforts in recent years have stressed, and expanded, the leadership role of the principal. But in the view of many analysts, the task of transforming a school is too complex for one person to accomplish alone. Consequently, a new model of leadership is developing: distributed leadership. This Research Roundup summarizes five…

  1. Nuclear structure theory. Annual technical progress report, October 1, 1979-August 31, 1980. [Univ. of Rochester

    SciTech Connect

    French, J.B.; Koltun, D.S.

    1980-01-01

    This report summarizes progress during the past year in the following areas of nuclear structure and reaction theory: statistical spectroscopy (including random matrix methods, with applications to fluctuations in spectra and in strength distributions, and to problems of ergodicity; group symmetries in spectral-distribution theory; electromagnetic and ..beta.. transitions); meson scattering and absorption by nuclei (including general scattering theory with absorption, multiple scattering theory and its reactive content, statistical theory of absorption); and meson currents in electromagnetic transitions.

  2. 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.

  3. A brief survey of rotary wing induced-velocity theory

    NASA Technical Reports Server (NTRS)

    Heyson, H. H.

    1978-01-01

    An attempt is made to summarize the state of rotary wing flow fields. The theory is traced from its origin as a momentum theory estimate of average interference, through simple vortex theory, to its present status where it is indispensible in calculating blade loads. A comparison of the theory with flow measurements are presented. The modern efforts toward using more detailed digital methods to obtain blade load distribution are described.

  4. Theories and Modes

    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…

  5. The Offence of Theory

    ERIC Educational Resources Information Center

    MacLure, Maggie

    2010-01-01

    Theory frequently offends. The paper argues that this is its strength: the value of theory lies in its power to get in the way. Theory is needed to block the reproduction of banality, and thereby, hopefully, open new possibilities for thinking and doing. However, I also note that theory has become somewhat disengaged from its objects, diminishing…

  6. Molecular structures, charge distributions, and vibrational analyses of the tetracoordinate Cu(II), Zn(II), Cd(II), and Hg(II) bromide complexes of p-toluidine investigated by density functional theory in comparison with experiments

    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.

  7. 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.

  8. 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.

  9. Nonrelativistic superstring theories

    SciTech Connect

    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.

  10. Distributive Justice and Distributive Quality.

    ERIC Educational Resources Information Center

    Wexler, Jacqueline Grennan

    American higher education in this century has been almost schizophrenic in its development. As money and knowledge began to spread more distributively across the population, the population began to demand for its children a more equitable access into the world of the more privileged. Education and privilege were highly correlated. Greater access…

  11. 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.

  12. 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…

  13. IR-Improved DGLAP-CS Theory

    DOE PAGESBeta

    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.

  14. 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.

  15. 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.

  16. Separation-individuation theory and attachment theory.

    PubMed

    Blum, Harold P

    2004-01-01

    Separation-individuation and attachment theories are compared and assessed in the context of psychoanalytic developmental theory and their application to clinical work. As introduced by Margaret Mahler and John Bowlby, respectively, both theories were initially regarded as diverging from traditional views. Separation-individuation theory, though it has had to be corrected in important respects, and attachment theory, despite certain limitations, have nonetheless enriched psychoanalytic thought. Without attachment an infant would die, and with severely insecure attachment is at greater risk for serious disorders. Development depends on continued attachment to a responsive and responsible caregiver. Continued attachment to the primary object was regarded by Mahler as as intrinsic to the process of separation-individuation. Attachment theory does not account for the essential development of separateness, and separation-individuation is important for the promotion of autonomy, independence, and identity. Salient historical and theoretical issues are addressed, including the renewed interest in attachment theory and the related decline of interest in separation-individuation theory. PMID:15222460

  17. 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…

  18. Phase-space quantization of field theory.

    SciTech Connect

    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.

  19. Distributed Leadership as Work Redesign: Retrofitting the Job Characteristics Model

    ERIC Educational Resources Information Center

    Mayrowetz, David; Murphy, Joseph; Louis, Karen Seashore; Smylie, Mark A.

    2007-01-01

    In this article, we revive work redesign theory, specifically Hackman and Oldham's Job Characteristics Model (JCM), to examine distributed leadership initiatives. Based on our early observations of six schools engaged in distributed leadership reform and a broad review of literature, including empirical tests of work redesign theory, we retrofit…

  20. Particle conservation in dynamical density functional theory

    NASA Astrophysics Data System (ADS)

    de las Heras, Daniel; Brader, Joseph M.; Fortini, Andrea; Schmidt, Matthias

    2016-06-01

    We present the exact adiabatic theory for the dynamics of the inhomogeneous density distribution of a classical fluid. Erroneous particle number fluctuations of dynamical density functional theory are absent, both for canonical and grand canonical initial conditions. We obtain the canonical free energy functional, which yields the adiabatic interparticle forces of overdamped Brownian motion. Using an exact and one of the most advanced approximate hard core free energy functionals, we obtain excellent agreement with simulations. The theory applies to finite systems in and out of equilibrium.

  1. Particle conservation in dynamical density functional theory.

    PubMed

    de Las Heras, Daniel; Brader, Joseph M; Fortini, Andrea; Schmidt, Matthias

    2016-06-22

    We present the exact adiabatic theory for the dynamics of the inhomogeneous density distribution of a classical fluid. Erroneous particle number fluctuations of dynamical density functional theory are absent, both for canonical and grand canonical initial conditions. We obtain the canonical free energy functional, which yields the adiabatic interparticle forces of overdamped Brownian motion. Using an exact and one of the most advanced approximate hard core free energy functionals, we obtain excellent agreement with simulations. The theory applies to finite systems in and out of equilibrium. PMID:27115673

  2. 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.

  3. 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…

  4. Equivalency Theory and Distance Education.

    ERIC Educational Resources Information Center

    Simonson, Michael

    1999-01-01

    Discusses distance education and the need for an accepted theory. Highlights include theories of independent study; theory of industrialization of teaching; theory of interaction and communication; and equivalency theory that is based on local control, personalized instruction, and telecommunications. (LRW)

  5. Distributed Saturation

    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.

  6. Multiagent distributed watershed management

    NASA Astrophysics Data System (ADS)

    Giuliani, M.; Castelletti, A.; Amigoni, F.; Cai, X.

    2012-04-01

    Deregulation and democratization of water along with increasing environmental awareness are challenging integrated water resources planning and management worldwide. The traditional centralized approach to water management, as described in much of water resources literature, is often unfeasible in most of the modern social and institutional contexts. Thus it should be reconsidered from a more realistic and distributed perspective, in order to account for the presence of multiple and often independent Decision Makers (DMs) and many conflicting stakeholders. Game theory based approaches are often used to study these situations of conflict (Madani, 2010), but they are limited to a descriptive perspective. Multiagent systems (see Wooldridge, 2009), instead, seem to be a more suitable paradigm because they naturally allow to represent a set of self-interested agents (DMs and/or stakeholders) acting in a distributed decision process at the agent level, resulting in a promising compromise alternative between the ideal centralized solution and the actual uncoordinated practices. Casting a water management problem in a multiagent framework allows to exploit the techniques and methods that are already available in this field for solving distributed optimization problems. In particular, in Distributed Constraint Satisfaction Problems (DCSP, see Yokoo et al., 2000), each agent controls some variables according to his own utility function but has to satisfy inter-agent constraints; while in Distributed Constraint Optimization Problems (DCOP, see Modi et al., 2005), the problem is generalized by introducing a global objective function to be optimized that requires a coordination mechanism between the agents. In this work, we apply a DCSP-DCOP based approach to model a steady state hypothetical watershed management problem (Yang et al., 2009), involving several active human agents (i.e. agents who make decisions) and reactive ecological agents (i.e. agents representing

  7. 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.

  8. [Mathematics and string theory

    SciTech Connect

    Jaffe, A.; Yau, Shing-Tung.

    1993-01-01

    Work on this grant was centered on connections between non- commutative geometry and physics. Topics covered included: cyclic cohomology, non-commutative manifolds, index theory, reflection positivity, space quantization, quantum groups, number theory, etc.

  9. Dissipative Field Theory

    SciTech Connect

    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.

  10. Theories of Career Development. A Comparison of the Theories.

    ERIC Educational Resources Information Center

    Osipow, Samuel H.

    These seven theories of career development are examined in previous chapters: (1) Roe's personality theory, (2) Holland's career typology theory, (3) the Ginzberg, Ginsburg, Axelrod, and Herma Theory, (4) psychoanalytic conceptions, (5) Super's developmental self-concept theory, (6) other personality theories, and (7) social systems theories.…

  11. Hadron Structures from Large Momentum Effective Field Theory

    NASA Astrophysics Data System (ADS)

    Xiong, Xiaonu

    2016-08-01

    The large momentum effective field theory (LaMET) is aiming to calculate parton distributions directly on lattice. In this approach a class of so-called quasi distributions are defined as pure spatial correlations in a finite momentum frame and they are directly calculated on lattice. The light-cone distributions are extracted from the quasi distributions by perturbative matching conditions. We present the application of LaMET on parton distribution functions and generalized parton distributions. Besides, heavy meson's quasi and light-cone distribution amplitudes are studied under nonrelativistic QCD (NRQCD) factorization framework.

  12. Modern Theories of Language.

    ERIC Educational Resources Information Center

    Davis, Philip W.

    This volume explores objectively the essential characteristic of nine twentieth-century linguistic theories with the theoretical variant for discussion based on one closely representative of work within a given approach or usually associated with the name of the theory. First, the theory of Ferdinand de Saussure is discussed based on his book,…

  13. Constructor theory of probability

    PubMed Central

    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

  14. Testing Theory through Theatrics.

    ERIC Educational Resources Information Center

    Sellers, Sandra Courtney

    2002-01-01

    In a nursing theory course, the final exam consists of a role play in which students assume the identity of a theorist they have studied and answer questions in the context of that role. Questions are designed demonstrate their knowledge of major nursing theories and models and the relevance of theory to practice. (SK)

  15. Whither Social Theory?

    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…

  16. Comparing Measurement Theories.

    ERIC Educational Resources Information Center

    Schumacker, Randall E.

    In comparing measurement theories, it is evident that the awareness of the concept of measurement error during the time of Galileo has lead to the formulation of observed scores comprising a true score and error (classical theory), universe score and various random error components (generalizability theory), or individual latent ability and error…

  17. 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…

  18. Activity Theory and Ontology

    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…

  19. Frankl's Theory and Therapy.

    ERIC Educational Resources Information Center

    Missinne, Leo E.; Wilcox, Victoria

    This paper discusses the life, theories, and therapeutic techniques of psychotherapist, Viktor E. Frankl. A brief biography of Frankl is included discussing the relationship of his early experiences as a physician to his theory of personality. Frankl's theory focusing on man's need for meaning and emphasizing the spiritual dimension in each human…

  20. Unstructured quantum key distribution

    NASA Astrophysics Data System (ADS)

    Coles, Patrick; Metodiev, Eric; Lutkenhaus, Norbert

    Quantum key distribution (QKD) allows for communication with security guaranteed by quantum theory. The main theoretical problem in QKD is to calculate the secret key rate for a given protocol. Analytical formulas are known for protocols with a high degree of symmetry, since symmetry simplifies the analysis. However, experimental imperfections break symmetries, hence the effect of imperfections on key rates is difficult to estimate. Furthermore, it is an interesting question whether (intentionally) asymmetric protocols could outperform symmetric ones. In this work, we develop a robust numerical approach for calculating the key rate for arbitrary discrete-variable QKD protocols. Ultimately this will allow researchers to study ``unstructured'' protocols, i.e., those that lack symmetry. Our approach relies on transforming the key rate calculation to the dual optimization problem, which dramatically reduces the number of parameters and hence the calculation time. We illustrate our method by investigating some unstructured protocols for which the key rate was previously unknown.

  1. Theory of powdery rubber wear.

    PubMed

    Persson, B N J

    2009-12-01

    Rubber wear typically involves the removal of small rubber particles from the rubber surface. On surfaces with not too sharp roughness, e.g. most road surfaces, this involves (slow) crack propagation. In this paper I shall present a theory of mild rubber wear. I shall derive the distribution of wear particle sizes Φ(D), which is in excellent agreement with experiment. I shall also show that the calculated wear rate is consistent with experimental data for tire tread block wear. PMID:21832508

  2. 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)

  3. Distributed visualization

    SciTech Connect

    Arnold, T.R.

    1991-12-31

    Within the last half decade or so, two technological evolutions have culminated in mature products of potentially great utility to computer simulation. One is the emergence of low-cost workstations with versatile graphics and substantial local CPU power. The other is the adoption of UNIX as a de facto ``standard`` operating system on at least some machines offered by virtually all vendors. It is now possible to perform transient simulations in which the number- crunching capability of a supercomputer is harnessed to allow both process control and graphical visualization on a workstation. Such a distributed computer system is described as it now exists: a large FORTRAN application on a CRAY communicates with the balance of the simulation on a SUN-3 or SUN-4 via remote procedure call (RPC) protocol. The hooks to the application and the graphics have been made very flexible. Piping of output from the CRAY to the SUN is nonselective, allowing the user to summon data and draw or plot at will. The ensemble of control, application, data handling, and graphics modules is loosely coupled, which further generalizes the utility of the software design.

  4. Distributed visualization

    SciTech Connect

    Arnold, T.R.

    1991-01-01

    Within the last half decade or so, two technological evolutions have culminated in mature products of potentially great utility to computer simulation. One is the emergence of low-cost workstations with versatile graphics and substantial local CPU power. The other is the adoption of UNIX as a de facto standard'' operating system on at least some machines offered by virtually all vendors. It is now possible to perform transient simulations in which the number- crunching capability of a supercomputer is harnessed to allow both process control and graphical visualization on a workstation. Such a distributed computer system is described as it now exists: a large FORTRAN application on a CRAY communicates with the balance of the simulation on a SUN-3 or SUN-4 via remote procedure call (RPC) protocol. The hooks to the application and the graphics have been made very flexible. Piping of output from the CRAY to the SUN is nonselective, allowing the user to summon data and draw or plot at will. The ensemble of control, application, data handling, and graphics modules is loosely coupled, which further generalizes the utility of the software design.

  5. Theory Interpretations in PVS

    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.

  6. Rate theories for biologists

    PubMed Central

    Zhou, Huan-Xiang

    2012-01-01

    Some of the rate theories that are most useful for modeling biological processes are reviewed. By delving into some of the details and subtleties in the development of the theories, the review will hopefully help the reader gain a more than superficial perspective. Examples are presented to illustrate how rate theories can be used to generate insight at the microscopic level into biomolecular behaviors. Attempt is made to clear up a number of misconceptions in the literature regarding popular rate theories, including the appearance of Planck’s constant in the transition-state theory and the Smoluchowski result as an upper limit for protein-protein and protein-DNA association rate constants. Future work in combining the implementation of rate theories through computer simulations with experimental probes of rate processes, and in modeling effects of intracellular environments so theories can be used for generating rate constants for systems biology studies is particularly exciting. PMID:20691138

  7. 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.

  8. Linear theory of frequency pulling in gyrotrons

    NASA Astrophysics Data System (ADS)

    Nusinovich, Gregory S.; Luo, Li; Liu, Pu-Kun

    2016-05-01

    The effect of the electron beam on the gyrotron operating frequency (the frequency pulling) is studied analytically in the framework of the linear (or small-signal) theory. The theory is applicable for gyrotrons operating at any cyclotron harmonics and in modes with arbitrary axial structures. The present consideration is limited to cases of operation at the fundamental cyclotron resonance and the second harmonic; also two specific axial profiles of the resonator modes are analyzed: the constant and the sinusoidal distributions. In the case of the sinusoidal distribution, we considered the operation in modes with one, two, and three axial variations. It is shown how to use the theory developed for analyzing the frequency tunability due to the frequency pulling effect in a gyrotron with specified parameters of the electron beam.

  9. 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.

  10. 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.

  11. Generalized Quantum Theory and Mathematical Foundations of Quantum Field Theory

    NASA Astrophysics Data System (ADS)

    Maroun, Michael Anthony

    This dissertation is divided into two main topics. The first is the generalization of quantum dynamics when the Schrodinger partial differential equation is not defined even in the weak mathematical sense because the potential function itself is a distribution in the spatial variable, the same variable that is used to define the kinetic energy operator, i.e. the Laplace operator. The procedure is an extension and broadening of the distributional calculus and offers spectral results as an alternative to the only other two known methods to date, namely a) the functional calculi; and b) non-standard analysis. Furthermore, the generalizations of quantum dynamics presented within give a resolution to the time asymmetry paradox created by multi-particle quantum mechanics due to the time evolution still being unitary. A consequence is the randomization of phases needed for the fundamental justification Pauli master equation. The second topic is foundations of the quantum theory of fields. The title is phrased as ``foundations'' to emphasize that there is no claim of uniqueness but rather a proposal is put forth, which is markedly different than that of constructive or axiomatic field theory. In particular, the space of fields is defined as a space of generalized functions with involutive symmetry maps (the CPT invariance) that affect the topology of the field space. The space of quantum fields is then endowed the Frechet property and interactions change the topology in such a way as to cause some field spaces to be incompatible with others. This is seen in the consequences of the Haag theorem. Various examples and discussions are given that elucidate a new view of the quantum theory of fields and its (lack of) mathematical structure.

  12. 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.

  13. Josephson Phase Qubit with a Distributed Reactance: Theory

    NASA Astrophysics Data System (ADS)

    Ferguson, David; Przybysz, Anthony; Naaman, Ofer; Strand, Joel; Medford, James; Pesetski, Aaron

    2014-03-01

    Recently, the Northrop Grumman's superconducting systems team designed, fabricated, and measured a novel phase qubit in which the shunt capacitance across the Josephson junction and the inductance of the SQUID are provided by a microstrip resonator. To account theoretically for this novel design we treat the superconducting phase drop along the microstrip's length as a continuous field. We present an analysis of this model, describing how the normal modes of the coupled system are influenced by both the applied flux and the microstrip's termination impedance, and how the non-linear coupling of the fundamental ``qubit mode'' to higher modes generates significant renormalizations of mode frequencies and anharmonicities.

  14. Education Policy, Distributed Leadership and Socio-Cultural Theory

    ERIC Educational Resources Information Center

    Hartley, David

    2009-01-01

    A current characteristic of governance in the public services in England is the advocacy of a permeation of once-discrete organizational and professional structures. New configurations are being called for. Examples are extended schools, workforce re-modelling, and multi-agency working. At issue here is a further indication of this loosening of…

  15. 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.

  16. Similarity Theory of Withdrawn Water Temperature Experiment

    PubMed Central

    2015-01-01

    Selective withdrawal from a thermal stratified reservoir has been widely utilized in managing reservoir water withdrawal. Besides theoretical analysis and numerical simulation, model test was also necessary in studying the temperature of withdrawn water. However, information on the similarity theory of the withdrawn water temperature model remains lacking. Considering flow features of selective withdrawal, the similarity theory of the withdrawn water temperature model was analyzed theoretically based on the modification of governing equations, the Boussinesq approximation, and some simplifications. The similarity conditions between the model and the prototype were suggested. The conversion of withdrawn water temperature between the model and the prototype was proposed. Meanwhile, the fundamental theory of temperature distribution conversion was firstly proposed, which could significantly improve the experiment efficiency when the basic temperature of the model was different from the prototype. Based on the similarity theory, an experiment was performed on the withdrawn water temperature which was verified by numerical method. PMID:26065020

  17. Second-order radio frequency kinetic theory revisited: Resolving inconsistency with conventional fluid theory

    SciTech Connect

    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.

  18. 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…

  19. 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…

  20. Relationships between digital signal processing and control and estimation theory

    NASA Technical Reports Server (NTRS)

    Willsky, A. S.

    1978-01-01

    Research areas associated with digital signal processing and control and estimation theory are identified. Particular attention is given to image processing, system identification problems (parameter identification, linear prediction, least squares, Kalman filtering), stability analyses (the use of the Liapunov theory, frequency domain criteria, passivity), and multiparameter systems, distributed processes, and random fields.

  1. New methods in potential theory

    NASA Astrophysics Data System (ADS)

    Kondratyev, B. P.

    2011-09-01

    A theory of equigravitating bodies by which external force fields of volumetric axially symmetric figures can be represented by unitary integrals is developed. This theory is being developed in three directions. The first is connected with the proof of the existence of equigravitating line segments. Such line segments can have both real and imaginary distributions of density; however, the mass and external potential remain real values. The ends of line segments coincide with special points (these are cusp points on the surfaces or special points of the analytical continuation of the external potential inside the body). At two special points, the body has only one line equigravitating segment, otherwise the line segments are compound or form equigravitating "skeletons." At the isolated special points, external gravitational fields can be presented by a set of line segments and mass points. The second direction is based on a representation of the external gravitational field of volumetric axially symmetric figures with an equator plane by means of potentials of flat round disks. Such disks are obtained on the line segments with symmetric density distributions. The return is always true: for homogeneous or any nonuniform round disk, it is possible to find an equigravitating line segment. It manages to construct chains of "spheroid-disk-line segment" equigravitating bodies. The third direction of this theory is connected with the development and expansion on the scope of the method of confocal transformations. This method is modified and applied not only to continuous homogeneous ellipsoids, but also to non-uniform stratified ellipsoids with a stratification of the general type, as well as to homogeneous and nonuniform shells. Any elementary or thick ellipsoidal shells (and continuous nonuniform stratified ellipsoids) connected by special confocal transformations equigravitate each other.

  2. Domains and Naive Theories

    PubMed Central

    Gelman, Susan A.; Noles, Nicholaus S.

    2013-01-01

    Human cognition entails domain-specific cognitive processes that influence memory, attention, categorization, problem-solving, reasoning, and knowledge organization. This review examines domain-specific causal theories, which are of particular interest for permitting an examination of how knowledge structures change over time. We first describe the properties of commonsense theories, and how commonsense theories differ from scientific theories, illustrating with children’s classification of biological and non-biological kinds. We next consider the implications of domain-specificity for broader issues regarding cognitive development and conceptual change. We then examine the extent to which domain-specific theories interact, and how people reconcile competing causal frameworks. Future directions for research include examining how different content domains interact, the nature of theory change, the role of context (including culture, language, and social interaction) in inducing different frameworks, and the neural bases for domain-specific reasoning. PMID:24187603

  3. Generalized higher gauge theory

    NASA Astrophysics Data System (ADS)

    Ritter, Patricia; Sämann, Christian; Schmidt, Lennart

    2016-04-01

    We study a generalization of higher gauge theory which makes use of generalized geometry and seems to be closely related to double field theory. The local kinematical data of this theory is captured by morphisms of graded manifolds between the canonical exact Courant Lie 2-algebroid T M ⊕ T ∗ M over some manifold M and a semistrict gauge Lie 2-algebra. We discuss generalized curvatures and infinitesimal gauge transformations. Finite gauge transformation as well as global kinematical data are then obtained from principal 2-bundles over 2-spaces. As dynamical principle, we consider first the canonical Chern-Simons action for such a gauge theory. We then show that a previously proposed 3-Lie algebra model for the six-dimensional (2,0) theory is very naturally interpreted as a generalized higher gauge theory.

  4. Galileo's tidal theory.

    PubMed

    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. PMID:17539198

  5. Extended theories of gravitation

    NASA Astrophysics Data System (ADS)

    Fatibene, Lorenzo; Garruto, Simon

    2016-04-01

    In this paper, we shall review the equivalence between Palatini-f(ℛ) theories and Brans-Dicke (BD) theories at the level of action principles. We shall define the Helmholtz Lagrangian associated to Palatini-f(ℛ) theory and we will define some transformations which will be useful to recover Einstein frame and BD frame. We shall see an explicit example of matter field and we will discuss how the conformal factor affects the physical quantities.

  6. Theory Modeling and Simulation

    SciTech Connect

    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.

  7. Automated Lattice Perturbation Theory

    SciTech Connect

    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.

  8. The theory of flotation

    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.

  9. 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.

  10. The Big Bang Theory

    SciTech Connect

    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.

  11. Ostwald ripening theory

    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.

  12. Why Do We Have Theories?

    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…

  13. Fluid distributions in random media - Arbitrary matrices

    NASA Astrophysics Data System (ADS)

    Madden, William G.

    1992-04-01

    The graphical theory of Madden and Glandt (1988) for a fluid adsorbed into a quenched medium is extended to situations in which the distribution of the immobile species has an arbitrary form, not necessarily arising from a thermal quench. The working equations of Madden and Glandt are shown to be applicable to this general case, and the approximations common in the theory of equilibrium mixtures are appropriate in this application as well. Extensions to mixtures are considered, and the connection with the graphical theory of small molecules is discussed.

  14. 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…

  15. Theory of fermion condensation as an analog of the liquid-drop theory of atomic nuclei

    SciTech Connect

    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.

  16. 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.

  17. Theories and Methodologies.

    ERIC Educational Resources Information Center

    Skemp, Richard R.

    Provided is an examination of the methodology used to study the problems of learning addition and subtraction skills used by developmental researchers. The report has sections on categories of theory and their methodologies, which review: (1) Behaviorist, Neo-Behaviorist and Piagetian Theories; (2) the Behaviorist and Piagetian Paradigms; (3)…

  18. 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.

  19. 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…

  20. Put Theory into Practice

    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.…

  1. Sexual Murderers' Implicit Theories

    ERIC Educational Resources Information Center

    Beech, Anthony; Fisher, Dawn; Ward, Tony

    2005-01-01

    Interviews with 28 sexual murderers were subjected to grounded theory analysis. Five implicit theories (ITs) were identified: dangerous world, male sex drive is uncontrollable, entitlement, women as sexual objects, and women as unknowable. These ITs were found to be identical to those identified in the literature as being present in rapists. The…

  2. Game Theory .net.

    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…

  3. Theory of thermoelasticity

    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.

  4. 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…

  5. Elementary Particle Theory

    SciTech Connect

    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.

  6. The Structure of Theory

    ERIC Educational Resources Information Center

    Skabelund, Donald E.

    1974-01-01

    Presents an analysis of scientific theory which is applicable to the full range of historical situations. Indicates that theory can be resolved into three generalization levels, one neutral element, and two modes. Included are examples illustrating the constituency of the three levels in two modes. (CC)

  7. Theory is personal.

    PubMed

    Siegel, Allen M

    2009-04-01

    In "Theory Is Personal," Allen Siegel MD, a Chicago psychoanalyst and Assistant Professor of Clinical Psychiatry at Rush University Medical Center, shares the very personal story of how he came to his theory. Sometimes we find our theory. Other times, Siegel argues, it is our theory that finds us. In this article Siegel catalogues his early encounters with figures--contemporary and real--from Sigmund Freud to influential department chairs to an analyst who would become legendary for introducing a bold new theory into the psychoanalytic canon. Charting key experiences that shaped his adoption of this new approach--a depression in response to his first patient, a clinical treatment with Heinz Kohut, and exposure to others who dared to challenge Freud--Siegel describes the theory that brought both himself and his patients to life. After outlining the principles that guide the new theory and practice known as self psychology, Siegel tells of the empathic ambiance that can now emerge in the consulting room. Finally, he shows how this new theory of human motivation provides not merely a rationale for psychotherapy but an explanatory apparatus for understanding human action in the world beyond the consulting room. He turns to a brief study of aggression and war, as expressed in a 1932 correspondence between Albert Einstein and Sigmund Freud, to illustrate how the understanding of aggression and war changes significantly when empathy is the field's data collecting instrument. PMID:19379249

  8. Evolution: Theory or Dogma?

    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)

  9. Greek Atomic Theory.

    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)

  10. 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…

  11. Reimagining Critical Theory

    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 at a…

  12. Evolution - A Theory Evolving

    ERIC Educational Resources Information Center

    Weinberg, Janet H.

    1975-01-01

    Presented is an explanation of a non-Darwinian theory of evolution based on the premise that functional differences are the result of many small mutations such as the substitution of one amino acid for another in a large protein molecule. A brief overview of Darwinian evolution and other theories are presented. (EB)

  13. 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…

  14. The Learning Theory Jungle

    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…

  15. Greek atomic theory

    NASA Astrophysics Data System (ADS)

    Roller, Duane H. D.

    1981-03-01

    Physics began about 600 B.C. with the Ionian Greeks and reached full development within three centuries. 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.

  16. 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…

  17. 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

  18. Dual double field theory

    NASA Astrophysics Data System (ADS)

    Bergshoeff, Eric A.; Hohm, Olaf; Penas, Victor A.; Riccioni, Fabio

    2016-06-01

    We present the dual formulation of double field theory at the linearized level. This is a classically equivalent theory describing the duals of the dilaton, the Kalb-Ramond field and the graviton in a T-duality or O( D, D) covariant way. In agreement with previous proposals, the resulting theory encodes fields in mixed Young-tableau representations, combining them into an antisymmetric 4-tensor under O( D, D). In contrast to previous proposals, the theory also requires an antisymmetric 2-tensor and a singlet, which are not all pure gauge. The need for these additional fields is analogous to a similar phenomenon for "exotic" dualizations, and we clarify this by comparing with the dualizations of the component fields. We close with some speculative remarks on the significance of these observations for the full non-linear theory yet to be constructed.

  19. Algebraic Mean Field Theory

    NASA Astrophysics Data System (ADS)

    Dankova, T. S.; Rosensteel, G.

    1998-10-01

    Mean field theory has an unexpected group theoretic mathematical foundation. Instead of representation theory which applies to most group theoretic quantum models, Hartree-Fock and Hartree-Fock-Bogoliubov have been formulated in terms of coadjoint orbits for the groups U(n) and O(2n). The general theory of mean fields is formulated for an arbitrary Lie algebra L of fermion operators. The moment map provides the correspondence between the Hilbert space of microscopic wave functions and the dual space L^* of densities. The coadjoint orbits of the group in the dual space are phase spaces on which time-dependent mean field theory is equivalent to a classical Hamiltonian dynamical system. Indeed it forms a finite-dimensional Lax system. The mean field theories for the Elliott SU(3) and symplectic Sp(3,R) algebras are constructed explicitly in the coadjoint orbit framework.

  20. Catastrophe theory in physics

    NASA Astrophysics Data System (ADS)

    Stewart, I.

    1982-02-01

    A discussion is presented of catastrophe theory, with attention to the developmental feedback between this field of mathematics and its applications in the physical sciences. Prominent concepts of catastrophe theory are co-dimension, determinacy, unfoldings, and organizing centers. The ways in which these concepts may be used are shown in light of specific applications taken from the literature, and the methods are generalized to areas not yet recognized to be within the purview of catastrophe theory. Note is taken of the philosophical background provided for this body of theory by the topological dynamics concept of structural stability. Catastrophe theory is in conclusion characterized as an important contribution to the understanding of nonlinear phenomena.

  1. 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

  2. Dempster-Shafer theory and connections to information theory

    NASA Astrophysics Data System (ADS)

    Peri, Joseph S. J.

    2013-05-01

    The Dempster-Shafer theory is founded on probability theory. The entire machinery of probability theory, and that of measure theory, is at one's disposal for the understanding and the extension of the Dempster-Shafer theory. It is well known that information theory is also founded on probability theory. Claude Shannon developed, in the 1940's, the basic concepts of the theory and demonstrated their utility in communications and coding. Shannonian information theory is not, however, the only type of information theory. In the 1960's and 1970's, further developments in this field were made by French and Italian mathematicians. They developed information theory axiomatically, and discovered not only the Wiener- Shannon composition law, but also the hyperbolic law and the Inf-law. The objective of this paper is to demonstrate the mathematical connections between the Dempster Shafer theory and the various types of information theory. A simple engineering example will be used to demonstrate the utility of the concepts.

  3. 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.

  4. Quantum Theory and Beyond

    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

  5. 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.

  6. Introduction to string theory and conformal field theory

    SciTech Connect

    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.

  7. Field-theory methods in coagulation theory

    SciTech Connect

    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.

  8. Field-theory methods in coagulation theory

    NASA Astrophysics Data System (ADS)

    Lushnikov, A. A.

    2011-08-01

    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 1, n 2, ..., n g , ...}, where n g is the total number of particles containing precisely g monomers. Thereupon, one introduces the generating functional Ψ for the probability W( Q, t). The time evolution of Ψ is described by an equation that is similar to the Schrödinger 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.

  9. Le fonctionnalisme parmi quelques theories syntaxiques (Functionalism among Several Syntactic Theories)

    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)

  10. Cohomology Methods in Causal Perturbation Theory

    NASA Astrophysics Data System (ADS)

    Grigore, D. R.

    2010-01-01

    Various problems in perturbation theory of (quantum) gauge models can be rephrased in the language of cohomology theory. This was already noticed in the functional formulation of perturbative gauge theories. Causal perturbation theory is a fully quantum approach: is works only with the chronological products which are defined as operator-valued distributions in the Fock space of the model. The use of causal perturbation theory leads to similar cohomology problems; the main difference with respect to the functional methods comes from the fact that the gauge transformation of the causal approach is, essentially, the linear part of the non-linear BRST transformation. Using these methods it is possible to give a nice determination of the interaction Lagrangians for gauge models (Yang-Mills and gravitation in the linear approximation); one obtains with this method the unicity of the interaction Lagrangian up to trivial terms. The case of quantum gravity is highly non-trivial and can be generalized with this method to the massive graviton case. Going to higher orders of perturbation theory one finds quantum anomalies. Again the cohomological methods can be used to determine the generic form of these anomalies. Finally, one can investigate the arbitrariness of the chronological products in higher orders and reduce this problem to cohomology methods also.

  11. Set theory and physics

    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.

  12. Set theory and physics

    SciTech Connect

    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 {open_quotes}solution of supertasks,{close_quotes} and (iv) for weak solutions. Several approaches to set theory and their advantages and disadvantages for physical applications are discussed: Cantorian {open_quotes}naive{close_quotes} (i.e., nonaxiomatic) set theory, contructivism, and operationalism. In the author`s opinion, an attitude, of {open_quotes}suspended attention{close_quotes} (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 {open_quotes}bizarre{close_quotes} or {open_quotes}mindboggling{close_quotes} new formalisms, which need not be operationalizable or testable at the time of their creation, but which may successfully lead to novel fields of phenomenology and technology.

  13. theories of class

    NASA Astrophysics Data System (ADS)

    Gaiotto, Davide; Razamat, Shlomo S.

    2015-07-01

    We construct classes of superconformal theories elements of which are labeled by punctured Riemann surfaces. Degenerations of the surfaces correspond, in some cases, to weak coupling limits. Different classes are labeled by two integers ( N, k). The k = 1 case coincides with A N - 1 theories of class and simple examples of theories with k > 1 are orbifolds of some of the A N - 1 class theories. For the space of theories to be complete in an appropriate sense we find it necessary to conjecture existence of new strongly coupled SCFTs. These SCFTs when coupled to additional matter can be related by dualities to gauge theories. We discuss in detail the A 1 case with k = 2 using the supersymmetric index as our analysis tool. The index of theories in classes with k > 1 can be constructed using eigenfunctions of elliptic quantum mechanical models generalizing the Ruijsenaars-Schneider integrable model. When the elliptic curve of the model degenerates these eigenfunctions become polynomials with coefficients being algebraic expressions in fugacities, generalizing the Macdonald polynomials with rational coefficients appearing when k = 1.

  14. Heterogeneous Viscoelasticity: A Combined Theory of Dynamic and Elastic Heterogeneity.

    PubMed

    Schirmacher, Walter; Ruocco, Giancarlo; Mazzone, Valerio

    2015-07-01

    We present a heterogeneous version of Maxwell's theory of viscoelasticity based on the assumption of spatially fluctuating local viscoelastic coefficients. The model is solved in coherent-potential approximation. The theory predicts an Arrhenius-type temperature dependence of the viscosity in the vanishing-frequency limit, independent of the distribution of the activation energies. It is shown that this activation energy is generally different from that of a diffusing particle with the same barrier-height distribution, which explains the violation of the Stokes-Einstein relation observed frequently in glasses. At finite but low frequencies, the theory describes low-temperature asymmetric alpha relaxation. As examples, we report the good agreement obtained for selected inorganic, metallic, and organic glasses. At high frequencies, the theory reduces to heterogeneous elasticity theory, which explains the occurrence of the boson peak and related vibrational anomalies. PMID:26182108

  15. Quaternionic quantum field theory

    SciTech Connect

    Adler, S.L.

    1985-08-19

    We show that a quaternionic quantum field theory can be formulated when the numbers of bosonic and fermionic degrees of freedom are equal and the fermions, as well as the bosons, obey a second-order wave equation. The theory is initially defined in terms of a quaternion-imaginary Lagrangian using the Feynman sum over histories. A Schroedinger equation can be derived from the functional integral, which identifies the quaternion-imaginary quantum Hamiltonian. Conversely, the transformation theory based on this Hamiltonian can be used to rederive the functional-integral formulation.

  16. Splines and control theory

    NASA Technical Reports Server (NTRS)

    Zhang, Zhimin; Tomlinson, John; Martin, Clyde

    1994-01-01

    In this work, the relationship between splines and the control theory has been analyzed. We show that spline functions can be constructed naturally from the control theory. By establishing a framework based on control theory, we provide a simple and systematic way to construct splines. We have constructed the traditional spline functions including the polynomial splines and the classical exponential spline. We have also discovered some new spline functions such as trigonometric splines and the combination of polynomial, exponential and trigonometric splines. The method proposed in this paper is easy to implement. Some numerical experiments are performed to investigate properties of different spline approximations.

  17. On the asymptotic distribution of block-modified random matrices

    NASA Astrophysics Data System (ADS)

    Arizmendi, Octavio; Nechita, Ion; Vargas, Carlos

    2016-01-01

    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.

  18. 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…

  19. CONSTRUCTION OF EDUCATIONAL THEORY MODELS.

    ERIC Educational Resources Information Center

    MACCIA, ELIZABETH S.; AND OTHERS

    THIS STUDY DELINEATED MODELS WHICH HAVE POTENTIAL USE IN GENERATING EDUCATIONAL THEORY. A THEORY MODELS METHOD WAS FORMULATED. BY SELECTING AND ORDERING CONCEPTS FROM OTHER DISCIPLINES, THE INVESTIGATORS FORMULATED SEVEN THEORY MODELS. THE FINAL STEP OF DEVISING EDUCATIONAL THEORY FROM THE THEORY MODELS WAS PERFORMED ONLY TO THE EXTENT REQUIRED TO…

  20. 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)

  1. Angular distribution of turbulence in wave space

    NASA Technical Reports Server (NTRS)

    Coleman, G.; Ferziger, J. H.; Bertoglio, J. P.

    1987-01-01

    An alternative to the one-point closure model for turbulence, the large eddy simulation (LES), together with its more exact relative, direct numerical simulation (DNS) are discussed. These methods are beginning to serve as partial substitutes for turbulence experiments. The eddy damped quasi-normal Markovian (EDQNM) theory is reviewed. Angular distribution of the converted data was examined in relationship to EDQNM.

  2. Lift distribution in a rectangular jet

    NASA Technical Reports Server (NTRS)

    Jameson, A.

    1971-01-01

    Computer programs predict effect of slipstream-wing flow interaction on aerodynamic characteristics of deflected slipstream and tilt aircraft. One program calculates lift distribution, lift, and drag of wing in wide slipstream. Results permit development of simplified lifting surface theory for circular jet.

  3. Distributed Cognition: A Foundation for Performance Support.

    ERIC Educational Resources Information Center

    Greenberg, Jan D.; Dickelman, Gary J.

    2000-01-01

    Discusses distributed cognition theory, a viable framework and methodology for examining interactions between individuals and artifacts, and how it relates to performance support. Highlights include knowledge representation; applications in learning and performance support; learning communities; collaborative learning; and computer technology and…

  4. Theories of galaxy formation

    SciTech Connect

    Jones, B.J.T.

    1980-01-01

    The current status of some theories of galaxy formation that are consistent with the hot big bang origin of the universe is reviewed. In the cosmic turbulence theory, an attempt is made to explain not only the characteristic masses and angular momenta of galaxies, but to describe in detail the spectrum of galaxy clustering problems with regard to the observed abundances of the light elements, a Kolmogorov spectrum of turbulence and the fireball are discussed. Attention is given to a primordial chaotic magnetic field, the comparison between baryon-symmetric cosmologies, the origin of galactic spin and theories starting from isothermal perturbations. Also considered are the dilemma of the initial conditions with respect to the era after 10 to the -4th s, and the pancake theory, in which the planar structures that arise provide a natural explanation for filamentary structures.

  5. Electromagnetic scattering theory

    NASA Technical Reports Server (NTRS)

    Bird, J. F.; Farrell, R. A.

    1986-01-01

    Electromagnetic scattering theory is discussed with emphasis on the general stochastic variational principle (SVP) and its applications. The stochastic version of the Schwinger-type variational principle is presented, and explicit expressions for its integrals are considered. Results are summarized for scalar wave scattering from a classic rough-surface model and for vector wave scattering from a random dielectric-body model. Also considered are the selection of trial functions and the variational improvement of the Kirchhoff short-wave approximation appropriate to large size-parameters. Other applications of vector field theory discussed include a general vision theory and the analysis of hydromagnetism induced by ocean motion across the geomagnetic field. Levitational force-torque in the magnetic suspension of the disturbance compensation system (DISCOS), now deployed in NOVA satellites, is also analyzed using the developed theory.

  6. Wormholes in string theory

    SciTech Connect

    Lyons, A. ); Hawking, S.W. )

    1991-12-15

    We discuss the wormhole effective interactions in string theory, thought of as a sum over two-dimensional field theories on different world sheets. The effective interactions are calculated in the dilute wormhole approximation,'' initially by considering the Green's functions on higher-genus Riemann surfaces, and then by calculating the effect of a complete basis of wave functions on scattering amplitudes for a surface with a boundary. The sum over wormholes is equivalent to having a world sheet of trivial topology and summing over different space-time and matter-field backgrounds. To leading order these consist of the massless fluctuations, since the tachyon cancels out when a sum is done over different spin structures going through the wormhole. In this way we recover quantized general relativity as an effective theory, from a sum over field theories on higher-genus Riemann surfaces.

  7. Why We "Knead" Theory

    ERIC Educational Resources Information Center

    Gunter, Helen M.

    2013-01-01

    This article reports on a seminar by the Critical Educational Policy and Leadership Research Interest Group in June 2012. The article reports on the papers and our engagement with the need to use theory to develop descriptions and understandings.

  8. Little M-theory

    NASA Astrophysics Data System (ADS)

    Cheng, Hsin-Chia; Thaler, Jesse; Wang, Lian-Tao

    2006-09-01

    Using the language of theory space, i.e. moose models, we develop a unified framework for studying composite Higgs models at the LHC. This framework — denoted little M-theory — is conveniently described by a theoretically consistent three-site moose diagram which implements minimal flavor and isospin violation. By taking different limits of the couplings, one can interpolate between simple group-like and minimal moose-like models with and without T-parity. In this way, little M-theory reveals a large model space for composite Higgs theories. We argue that this framework is suitable as a starting point for a comprehensive study of composite Higgs scenarios. The rich collider phenomenology of this framework is briefly discussed.

  9. Classical Aerodynamic Theory

    NASA Technical Reports Server (NTRS)

    Jones, R. T. (Compiler)

    1979-01-01

    A collection of papers on modern theoretical aerodynamics is presented. Included are theories of incompressible potential flow and research on the aerodynamic forces on wing and wing sections of aircraft and on airship hulls.

  10. Lectures on Dispersion Theory

    DOE R&D Accomplishments Database

    Salam, A.

    1956-04-01

    Lectures with mathematical analysis are given on Dispersion Theory and Causality and Dispersion Relations for Pion-nucleon Scattering. The appendix includes the S-matrix in terms of Heisenberg Operators. (F. S.)

  11. Combining Theory With Practice

    ERIC Educational Resources Information Center

    Houa, Souen

    1975-01-01

    Using specific examples, the author discusses how the Chinese educators link theory with practice in order to associate education with the three great revolutionary motive forces--the class struggle, the drive towards productivity, and scientific experimentation. (Author/RM)

  12. Motherhood: a discrepancy theory.

    PubMed

    Adams, Mary

    2015-01-01

    Motherhood is a highly anticipated and positive event for most women. Society has constructed many ideal images of motherhood, giving women standards to live up to, and many times setting them up for disappointment. When this disappointment occurs, an emotional reaction follows, which may be fear, guilt, or shame. However, some women are able to experience this mismatch between an ideal and actual self and adapt with minimal emotional reaction. There was not a nursing theory that described this phenomenon. "Self-Discrepancy: A Theory Relating Self and Affect" (Higgins, 1987), from the psychology discipline provided concepts and definitions that could be used to derive a nursing theory. The derivation resulted in a testable mid-range theory that could have a significant impact on nursing interventions for postpartum mood disorders. PMID:26062291

  13. Leonardo's Tree Theory.

    ERIC Educational Resources Information Center

    Werner, Suzanne K.

    2003-01-01

    Describes a series of activities exploring Leonardo da Vinci's tree theory that are designed to strengthen 8th grade students' data collection and problem solving skills in physical science classes. (KHR)

  14. Distributed series resistance effects in solar cells

    NASA Astrophysics Data System (ADS)

    Nielsen, L. D.

    1982-05-01

    A mathematical treatment is presented of the effects of one-dimensional distributed series resistance in solar cells. A general perturbation theory is developed, including consistently the induced spatial variation of diode current density and leading to a first-order equivalent lumped resistance of one third the total sheet resistance. For the case of diode characteristics of exponential type and distributed resistance of arbitrary size, unified numerical results are presented for both illuminated and dark characteristics. At high forward dark currents, the distributed series resistance is shown to cause an effective doubling of the 'diode quality factor'.

  15. Entangled Husimi Distribution and Complex Wavelet Transformation

    NASA Astrophysics Data System (ADS)

    Hu, Li-Yun; Fan, Hong-Yi

    2010-05-01

    Similar in spirit to the preceding work (Int. J. Theor. Phys. 48:1539, 2009) where the relationship between wavelet transformation and Husimi distribution function is revealed, we study this kind of relationship to the entangled case. We find that the optical complex wavelet transformation can be used to study the entangled Husimi distribution function in phase space theory of quantum optics. We prove that, up to a Gaussian function, the entangled Husimi distribution function of a two-mode quantum state | ψ> is just the modulus square of the complex wavelet transform of e^{-\\vert η \\vert 2/2} with ψ( η) being the mother wavelet.

  16. Linear phase distribution of acoustical vortices

    SciTech Connect

    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.

  17. Information theory perspective on network robustness

    NASA Astrophysics Data System (ADS)

    Schieber, Tiago A.; Carpi, Laura; Frery, Alejandro C.; Rosso, Osvaldo A.; Pardalos, Panos M.; Ravetti, Martín G.

    2016-01-01

    A crucial challenge in network theory is the study of the robustness of a network when facing a sequence of failures. In this work, we propose a dynamical definition of network robustness based on Information Theory, that considers measurements of the structural changes caused by failures of the network's components. Failures are defined here as a temporal process defined in a sequence. Robustness is then evaluated by measuring dissimilarities between topologies after each time step of the sequence, providing a dynamical information about the topological damage. We thoroughly analyze the efficiency of the method in capturing small perturbations by considering different probability distributions on networks. In particular, we find that distributions based on distances are more consistent in capturing network structural deviations, as better reflect the consequences of the failures. Theoretical examples and real networks are used to study the performance of this methodology.

  18. Quantum theory of multimode polariton condensation

    NASA Astrophysics Data System (ADS)

    Racine, David; Eastham, P. R.

    2014-08-01

    We develop a theory for the dynamics of the density matrix describing a multimode polariton condensate. In such a condensate several single-particle orbitals become highly occupied, due to stimulated scattering from reservoirs of high-energy excitons. A generic few-parameter model for the system leads to a Lindblad equation which includes saturable pumping, decay, and condensate interactions. We show how this theory can be used to obtain the population distributions, and the time-dependent first- and second-order coherence functions, in such a multimode condensate. As a specific application, we consider a polaritonic Josephson junction, formed from a double-well potential. We obtain the population distributions, emission line shapes, and widths (first-order coherence functions), and predict the dephasing time of the Josephson oscillations.

  19. Non-Perturbative Field Theories.

    NASA Astrophysics Data System (ADS)

    Stephenson, David

    Available from UMI in association with The British Library. Requires signed TDF. Some non-perturbative aspects of field theories are studied by applying lattice gauge theory techniques. The low-lying hadronic mass spectrum is calculated numerically using quenched lattice quantum chromodynamics. The results of large numerical simulations performed on a distributed array processor are presented and analysed. Particular emphasis is stressed upon the understanding of systematic and statistical errors in the calculation. In addition, the pion decay constant and the chiral condensate are evaluated. An attempt is made to relate the numerical findings to the experimentally measured quantities. A pioneering attempt to understand Yukawa couplings is discussed. A toy Fermion-Higgs system is studied numerically on a transputer array. Dynamical fermions are included in the investigation of the behavior of the system over a wide range of Yukawa couplings. A phase diagram is found for the model which shows evidence of spontaneous chiral symmetry breaking transitions. Extensions of the model are discussed together some speculations concerning the behaviour of Yukawa couplings in general. The possibility of using the lattice as a model for space-time is investigated by studying the propagation of particles on a fractal lattice. In addition, the use of truncated fractals as novel regulators is studied numerically in the hope that the problem of fermion doubling will be alleviated.

  20. Statistical inference and string theory

    NASA Astrophysics Data System (ADS)

    Heckman, Jonathan J.

    2015-09-01

    In this paper, we expose some surprising connections between string theory and statistical inference. We consider a large collective of agents sweeping out a family of nearby statistical models for an M-dimensional manifold of statistical fitting parameters. When the agents making nearby inferences align along a d-dimensional grid, we find that the pooled probability that the collective reaches a correct inference is the partition function of a nonlinear sigma model in d dimensions. Stability under perturbations to the original inference scheme requires the agents of the collective to distribute along two dimensions. Conformal invariance of the sigma model corresponds to the condition of a stable inference scheme, directly leading to the Einstein field equations for classical gravity. By summing over all possible arrangements of the agents in the collective, we reach a string theory. We also use this perspective to quantify how much an observer can hope to learn about the internal geometry of a superstring compactification. Finally, we present some brief speculative remarks on applications to the AdS/CFT correspondence and Lorentzian signature space-times.

  1. Towards a unification of unified theories of biodiversity.

    PubMed

    McGill, Brian J

    2010-05-01

    A unified theory in science is a theory that shows a common underlying set of rules that regulate processes previously thought to be distinct. Unified theories have been important in physics including the unification of electricity and magnetism and the unification of the electromagnetic with the weak nuclear force. Surprisingly, ecology, specifically the subfields of biodiversity and macroecology, also possess not one but at least six unified theories. This is problematic as only one unified theory is desirable. Superficially, the six unified theories seem very different. However, I show that all six theories use the same three rules or assertions to describe a stochastic geometry of biodiversity. The three rules are: (1) intraspecifically individuals are clumped together; (2) interspecifically global or regional abundance varies according to a hollow curve distribution; and (3) interspecifically individuals are placed without regard to individuals of other species. These three rules appear sufficient to explain local species abundance distributions, species-area relationships, decay of similarity of distance and possibly other patterns of biodiversity. This provides a unification of the unified theories. I explore implications of this unified theory for future research. PMID:20337695

  2. Instantons in string theory

    SciTech Connect

    Ahlén, Olof

    2015-12-17

    These proceedings from the second Caesar Lattes meeting in Rio de Janeiro 2015 are a brief introduction to how automorphic forms appear in the low energy effective action of maximally supersymmetric string theory. The explicit example of the R{sup 4}-interaction of type IIB string theory in ten dimensions is discussed. Its Fourier expansion is interpreted in terms of perturbative and non-perturbative contributions to the four graviton amplitude.

  3. Instantons in string theory

    NASA Astrophysics Data System (ADS)

    Ahlén, Olof

    2015-12-01

    These proceedings from the second Caesar Lattes meeting in Rio de Janeiro 2015 are a brief introduction to how automorphic forms appear in the low energy effective action of maximally supersymmetric string theory. The explicit example of the R4-interaction of type IIB string theory in ten dimensions is discussed. Its Fourier expansion is interpreted in terms of perturbative and non-perturbative contributions to the four graviton amplitude.

  4. Leadership and attachment theory.

    PubMed

    Bresnahan, Christopher G; Mitroff, Ian I

    2007-09-01

    Comments on the six articles contained in the special issue of the American Psychologist (January 2007) devoted to leadership, written by W. Bennis; S. J. Zaccaro; V. H. Vroom and A. G. Yago; B. J. Avolio; R. J. Sternberg; and R. J. Hackman and R. Wageman. The current authors opine that the inclusion of attachment theory in the study of leadership could strengthen leadership theories as a whole. PMID:17874909

  5. Nodal Diffusion & Transport Theory

    Energy Science and Technology Software Center (ESTSC)

    1992-02-19

    DIF3D solves multigroup diffusion theory eigenvalue, adjoint, fixed source, and criticality (concentration, buckling, and dimension search) problems in 1, 2, and 3-space dimensions for orthogonal (rectangular or cylindrical), triangular, and hexagonal geometries. Anisotropic diffusion theory coefficients are permitted. Flux and power density maps by mesh cell and regionwise balance integrals are provided. Although primarily designed for fast reactor problems, upscattering and internal black boundary conditions are also treated.

  6. Hell of a theory.

    PubMed

    Krueger, Joachim I

    2016-01-01

    The theory of group-selected Big God religions is a master narrative of cultural evolution. The evidence is a positive manifold of correlated assumptions and variables. Although provocative, the theory is overly elastic. Its critical ingredient - belief in Big Gods - is neither necessary nor sufficient to account for in-group prosociality and discipline. Four specific issues illustrate this elasticity. PMID:26948734

  7. Leadership styles and theories.

    PubMed

    Giltinane, Charlotte Louise

    It is useful for healthcare professionals to be able to identify the leadership styles and theories relevant to their nursing practice. Being adept in recognising these styles enables nurses to develop their skills to become better leaders, as well as improving relationships with colleagues and other leaders, who have previously been challenging to work with. This article explores different leadership styles and theories, and explains how they relate to nursing practice. PMID:23905259

  8. A beam theory for anisotropic materials

    NASA Technical Reports Server (NTRS)

    Bauchau, O. A.

    1985-01-01

    Beam theory plays an important role in structural analysis. The basic assumption is that initially plane sections remain plane after deformation, neglecting out-of-plane warpings. Predictions based on these assumptions are accurate for slender, solid, cross-sectional beams made out of isotropic materials. The beam theory derived in this paper from variational principles is based on the sole kinematic assumption that each section is infinitely rigid in its own plane, but free to warp out of plane. After a short review of the Bernoulli and Saint-Venant approaches to beam theory, a set of orthonormal eigenwarpings is derived. Improved solutions can be obtained by expanding the axial displacements or axial stress distribution in series of eigenwarpings and using energy principles to derive the governing equations. The improved Saint-Venant approach leads to fast converging solutions and accurate results are obtained considering only a few eigenwarping terms.

  9. Graphical Model Theory for Wireless Sensor Networks

    SciTech Connect

    Davis, William B.

    2002-12-08

    Information processing in sensor networks, with many small processors, demands a theory of computation that allows the minimization of processing effort, and the distribution of this effort throughout the network. Graphical model theory provides a probabilistic theory of computation that explicitly addresses complexity and decentralization for optimizing network computation. The junction tree algorithm, for decentralized inference on graphical probability models, can be instantiated in a variety of applications useful for wireless sensor networks, including: sensor validation and fusion; data compression and channel coding; expert systems, with decentralized data structures, and efficient local queries; pattern classification, and machine learning. Graphical models for these applications are sketched, and a model of dynamic sensor validation and fusion is presented in more depth, to illustrate the junction tree algorithm.

  10. Riemannian geometry of fluctuation theory: An introduction

    NASA Astrophysics Data System (ADS)

    Velazquez, Luisberis

    2016-05-01

    Fluctuation geometry was recently proposed as a counterpart approach of Riemannian geometry of inference theory (information geometry), which describes the geometric features of the statistical manifold M of random events that are described by a family of continuous distributions dpξ(x|θ). This theory states a connection among geometry notions and statistical properties: separation distance as a measure of relative probabilities, curvature as a measure about the existence of irreducible statistical correlations, among others. In statistical mechanics, fluctuation geometry arises as the mathematical apparatus of a Riemannian extension of Einstein fluctuation theory, which is also closely related to Ruppeiner geometry of thermodynamics. Moreover, the curvature tensor allows to express some asymptotic formulae that account for the system fluctuating behavior beyond the gaussian approximation, while curvature scalar appears as a second-order correction of Legendre transformation between thermodynamic potentials.

  11. Behavioral Theories of Negotiations and Their Relation to Public Employee Bargaining.

    ERIC Educational Resources Information Center

    Herring, J. Donald

    Recent research and theory on collective bargaining focuses on bargaining attitudes and behaviors. Walton and McKersie divided all bargaining into distributive and integrative. Distributive bargaining is competitive and based on an assumption of conflict of interest. Integrative bargaining is cooperative and based on the theory that power can be…

  12. Constructor theory of life

    PubMed Central

    Marletto, Chiara

    2015-01-01

    Neo-Darwinian evolutionary theory explains how the appearance of purposive design in the adaptations of living organisms can have come about without their intentionally being designed. The explanation relies crucially on the possibility of certain physical processes: mainly, gene replication and natural selection. In this paper, I show that for those processes to be possible without the design of biological adaptations being encoded in the laws of physics, those laws must have certain other properties. The theory of what these properties are is not part of evolution theory proper, yet without it the neo-Darwinian theory does not fully achieve its purpose of explaining the appearance of design. To this end, I apply constructor theory's new mode of explanation to express exactly within physics the appearance of design, no-design laws, and the logic of self-reproduction and natural selection. I conclude that self-reproduction, replication and natural selection are possible under no-design laws, the only non-trivial condition being that they allow digital information to be physically instantiated. This has an exact characterization in the constructor theory of information. I also show that under no-design laws an accurate replicator requires the existence of a ‘vehicle’ constituting, together with the replicator, a self-reproducer. PMID:25589566

  13. Warped conformal field theory

    NASA Astrophysics Data System (ADS)

    Detournay, Stéphane; Hartman, Thomas; Hofman, Diego M.

    2012-12-01

    We study field theories in two spacetime dimensions invariant under a chiral scaling symmetry that acts only on right-movers. The local symmetries include one copy of the Virasoro algebra and a U(1) current algebra. This differs from the two-dimensional conformal group but in some respects is equally powerful in constraining the theory. In particular, the symmetries on a torus lead to modular covariance of the partition function, which is used to derive a universal formula for the asymptotic density of states. For an application we turn to the holographic description of black holes in quantum gravity, motivated by the fact that the symmetries in the near-horizon geometry of any extremal black hole are identical to those of a two-dimensional field theory with chiral scaling. We consider two examples: black holes in warped AdS3 in topologically massive gravity and in string theory. In both cases, the density of states in the two-dimensional field theory reproduces the Bekenstein-Hawking entropy of black holes in the gravity theory.

  14. Theory of hydromagnetic turbulence

    NASA Technical Reports Server (NTRS)

    Montgomery, D.

    1983-01-01

    The present state of MHD turbulence theory as a possible solar wind research tool is surveyed. The theory is statistical, and does not make statements about individual events. The ensembles considered typically have individual realizations which differ qualitatively, unlike equilibrium statistical mechanics. Most of the theory deals with highly symmetric situations; most of these symmetries have yet to be tested in the solar wind. The applicability of MHD itself to solar wind parameters is highly questionable; yet it has no competitors, as a potentially comprehensive dynamical description. The purpose of solar wind research require sharper articulation. If they are to understand radial turbulent plasma flows from spheres, laboratory experiments and numerical solution of equations of motion may be cheap alternative to spacecraft. If "real life" information is demanded, multiple spacecraft with variable separation may be necessary to go further. The principal emphasis in the theory so far has been on spectral behavior for spatial covariances in wave number space. There is no respectable theory of these for highly anisotropic situations. A rather slow development of theory acts as a brake on justifiable measurement, at this point.

  15. Parity in knot theory

    SciTech Connect

    Manturov, Vassily O

    2010-06-29

    In this work we study knot theories with a parity property for crossings: every crossing is declared to be even or odd according to a certain preassigned rule. If this rule satisfies a set of simple axioms related to the Reidemeister moves, then certain simple invariants solving the minimality problem can be defined, and invariant maps on the set of knots can be constructed. The most important example of a knot theory with parity is the theory of virtual knots. Using the parity property arising from Gauss diagrams we show that even a gross simplification of the theory of virtual knots, namely, the theory of free knots, admits simple and highly nontrivial invariants. This gives a solution to a problem of Turaev, who conjectured that all free knots are trivial. In this work we show that free knots are generally not invertible, and provide invariants which detect the invertibility of free knots. The passage to ordinary virtual knots allows us to strengthen known invariants (such as the Kauffman bracket) using parity considerations. We also discuss other examples of knot theories with parity. Bibliography: 27 items.

  16. On complicity theory.

    PubMed

    Kline, A David

    2006-04-01

    The received account of whistleblowing, developed over the last quarter century, is identified with the work of Norman Bowie and Richard DeGeorge. Michael Davis has detailed three anomalies for the received view: the paradoxes of burden, missing harm and failure. In addition, he has proposed an alternative account of whistleblowing, viz., the Complicity Theory. This paper examines the Complicity Theory. The supposed anomalies rest on misunderstandings of the received view or misreadings of model cases of whistleblowing, for example, the Challenger disaster and the Ford Pinto. Nevertheless, the Complicity Theory is important for as in science the contrast with alternative competing accounts often helps us better understand the received view. Several aspects of the received view are reviewed and strengthened through comparison with Complicity Theory, including why whistleblowing needs moral justification. Complicity Theory is also critiqued. The fundamental failure of Complicity Theory is its failure to explain why government and the public encourage and protect whistleblowers despite the possibility of considerable harm to the relevant company in reputation, lost jobs, and lost shareholder value. PMID:16609713

  17. Chordwise load distribution of a simple rectangular wing

    NASA Technical Reports Server (NTRS)

    Wieghardt, Karl

    1940-01-01

    The chordwise distribution theory was taken over from the theory of the infinite wing. Since in this work a series expansion in b/t was used, the computation converges only for large aspect ratios. In this paper a useful approximate solution will be found also for wings with large chord - i.e., small aspect ratio.

  18. Information theory and solar energy collection

    SciTech Connect

    Patera, R.P.; Robertson, H.S.

    1980-07-15

    Information theory is applied to the problem of solar radiation collection. We find that the optimum solar concentrator corresponds to a perfect imaging system, i.e., one that images the entire sky on the absorber with no aberrations. For a nonisotropic distribution of radiation at the collector aperture, many thermally separated absorber segments are necessary at the absorber for optimum performance. The heat transfer fluid is first passed through the warm segments and then passed sequentially through the progressively hotter segments.

  19. A statistical, micromechanical theory of the compressive strength of brittle materials

    NASA Technical Reports Server (NTRS)

    Adams, M.; Sines, G.

    1978-01-01

    A general theory of the compressive strength of brittle materials is presented. This theory proposes that failure is brought about by structural weakening from accumulated crack damage which increases with the stress level. The statistics of the flaw distribution and the mechanism of crack initiation and extension are important. A sample calculation using the theory is given to demonstrate its application

  20. Theory for non-equilibrium statistical mechanics.

    PubMed

    Attard, Phil

    2006-08-21

    This paper reviews a new theory for non-equilibrium statistical mechanics. This gives the non-equilibrium analogue of the Boltzmann probability distribution, and the generalization of entropy to dynamic states. It is shown that this so-called second entropy is maximized in the steady state, in contrast to the rate of production of the conventional entropy, which is not an extremum. The relationships of the new theory to Onsager's regression hypothesis, Prigogine's minimal entropy production theorem, the Langevin equation, the formula of Green and Kubo, the Kawasaki distribution, and the non-equilibrium fluctuation and work theorems, are discussed. The theory is worked through in full detail for the case of steady heat flow down an imposed temperature gradient. A Monte Carlo algorithm based upon the steady state probability density is summarized, and results for the thermal conductivity of a Lennard-Jones fluid are shown to be in agreement with known values. Also discussed is the generalization to non-equilibrium mechanical work, and to non-equilibrium quantum statistical mechanics. As examples of the new theory two general applications are briefly explored: a non-equilibrium version of the second law of thermodynamics, and the origin and evolution of life. PMID:16883388